ACS Publications. Most Trusted. Most Cited. Most Read
Porphyrin–Anthracene Complexes: Potential in Triplet–Triplet Annihilation Upconversion
More

OR SEARCH CITATIONS

My Activity
Publications

Figure 1Loading Img
Download Hi-Res ImageDownload to MS-PowerPointCite This:J. Phys. Chem. C 2016, 120, 34, 19018-19026
  • Open Access
Article

Porphyrin–Anthracene Complexes: Potential in Triplet–Triplet Annihilation Upconversion
Click to copy article linkArticle link copied!

View Author Information
† Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 58 Gothenburg, Sweden
‡ Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Gothenburg, Sweden
*E-mail: [email protected]
Open PDFSupporting Information (1)

The Journal of Physical Chemistry C

Cite this: J. Phys. Chem. C 2016, 120, 34, 19018–19026
Click to copy citationCitation copied!
https://doi.org/10.1021/acs.jpcc.6b06298
Published August 9, 2016

Copyright © 2016 American Chemical Society. This publication is licensed under these Terms of Use.

Request reuse permissions

Abstract

Click to copy section linkSection link copied!
High Resolution Image
Download MS PowerPoint Slide

Triplet–triplet annihilation photon upconversion (TTA-UC) systems contain both an absorbing and an emitting molecule, the sensitizer and annihilator, respectively. Through a series of energy-transfer steps, two low frequency photons can be combined into one high frequency photon. In organic solvents, the required energy transfer steps are limited by diffusion and are relatively efficient. In solid-state systems, however, the diffusion is slower, which usually results in lower efficiencies for these systems. An interesting way around this is to connect the sensitizer and annihilator. In order to increase understanding of the TTA-UC process in supramolecular systems, we synthesized four pyridine-substituted anthracene annihilators capable of coordinating axially to a zinc octaethylporphyrin sensitizer with a maximum binding constant of 6000 M–1 in toluene. This is a first example of a sensitizer–annihilator coordination complex for TTA-UC. Both the upconversion efficiency and the parasitic quenching of excited annihilator singlets by the sensitizer through Förster resonant energy transfer (FRET) were studied. On the basis of the findings herein, possible strategies for future supramolecular TTA systems with minimized FRET quenching are discussed.

Copyright © 2016 American Chemical Society

Subjects

what are subjects

Introduction

Click to copy section linkSection link copied!
Energy transfer in porphyrin–chromophore assemblies have been long studied. The interest stems from nature’s way, in photosynthesis, of using antenna structures to funnel absorbed photon energy to a reaction site. This concept has been employed in many photochemical systems, (1, 2) and it is perhaps surprising that little attention has been focused on utilizing this for sensitized triplet–triplet annihilation (TTA) photon upconversion.
The process of generating high energy photons from two low energy photons is commonly known as photon upconversion (UC). Photon upconversion through TTA of organic chromophores, which can generate upconverted emission from incoherent low intensity light, (3-9) has been suggested (10-13) and, to some extent, demonstrated to be a viable means of utilizing sub-band-gap photons in solar energy applications. (14-21)
Typically, triplet–triplet annihilation upconversion occurs in a bimolecular system containing a triplet sensitizer, commonly palladium or platinum porphyrins, and an annihilator species, typically polyaromatic molecules. The process is described in Figure 1. First, a low energy photon is absorbed by the sensitizer (S), which readily undergoes intersystem crossing (ISC) to form its first excited triplet state (3S*). Subsequently, the triplet state of the annihilator (3A*) is populated through a triplet-energy transfer (TET) process from the sensitizer. Two triplet excited annihilators then interact and undergo TTA, and this might result in the formation of one singlet excited annihilator (1A*) and one annihilator in the ground state (1A). The singlet excited annihilator subsequently relaxes to the ground state through fluorescence, emitting a photon of higher frequency than the ones initially absorbed.

Figure 1

Figure 1. Jablonski diagram explaining the triplet–triplet annihilation upconversion process. A sensitizer first absorbs a low energy photon and rapidly populates its first triplet excited state after ISC from the singlet state. The triplet energy is then transferred to an annihilator species through TET, generating one triplet excited annihilator molecule. When two triplet excited annihilator molecules come together they can undergo TTA to form a singlet excited annihilator which can deactivate to its ground state by emitting a photon. If the sensitizer and annihilator are in close proximity, e.g., when connected, a new deactivation pathway is possible, namely singlet energy transfer of the excited singlet annihilator, short-circuiting the system.

High Resolution Image
Download MS PowerPoint Slide
In solution, with suitable concentrations, the energy-transfer steps required for TTA-UC are efficient. For example, the triplet energy transfer from sensitizer to annihilator can be almost quantitative with a large excess of the annihilator. For applications, solid-state TTA-UC systems are required, and the general direction of the field is, thus, toward such systems. However, in solid-state materials the energy-transfer steps are not as straightforward to control, and therefore, it is important to study sensitizer–annihilator assemblies. (22) For example, Kimizuka and co-workers have recently presented an elegant way of enhancing the triplet-migration and subsequent TTA in metal–organic framworks (MOFs) leading to near-unit TTA efficiency. (23, 24) However, the TET from sensitizer to the annihilator in these studies was not as efficient as in solution-dissolved systems, and further optimization of this energy-transfer step was suggested. (23, 24)
As TTA-UC requires energy transfer from a sensitizer to an annihilator, the idea of connecting the two to enhance the energy transfer in solid systems is not completely new, and examples of covalently linked sensitizer–annihilator dyads in solution exist in the literature. (25-28) However, these systems were less efficient than the corresponding nonconnected system due to quenching of the upconverted singlet excited state through energy transfer back to the sensitizer. Understanding the effect on TTA-UC in supramolecular sensitizer–annihilator assemblies is necessary for future applications that would require efficient, solid-state upconversion materials.
We have chosen to investigate a series of sensitizer–annihilator complexes, their upconversion properties, and the parasitic singlet energy transfer from annihilator back to the sensitizer. It has been suggested previously that axial coordination of anthracene to a Sn(IV) porphyrin excludes singlet energy transfer through Förster resonance energy transfer (FRET) from the anthracene to porphyrin. (29) We therefore designed, synthesized, and studied four anthracene derivatives capable of axially coordinating to a zinc porphyrin and here present a first example of sensitizer–annihilator coordination complexes used for TTA-UC. The possible energy-transfer steps in the coordinated systems are schematically illustrated in Figure 1.
The annihilator species in the study are based on 9,10-diphenylanthracene (DPA), which is one of the benchmark annihilators. (21) Pyridine as a terminal group on one side of the phenylanthracene was chosen in order to achieve coordination of the nitrogen lone pairs to the zinc(II) octaethylporphyrin (ZnOEP) metal center. The terminal pyridine was separated from the anthracene moiety with 0, 1, 2, or 4 phenyl groups, Ph1–5AnPyr in Figure 2. For solubility reasons, Ph5AnPyr was modified with solubilizing 2-ethylhexyl side chains.

Figure 2

Figure 2. Molar absorptivity (solid) and normalized fluorescence (dashed) of the studied annihilators DPA (black), Ph1AnPyr (orange), Ph2AnPyr (blue), Ph3AnPyr (green), and Ph5AnPyr (red) and the sensitizer ZnOEP (gray).

High Resolution Image
Download MS PowerPoint Slide
As sensitizer, a metal porphyrin with a transition metal capable of bonding with the nitrogen lone pairs had to be used, and therefore, the standard palladium and platinum octaethylporphyrins commonly used with DPA could not be utilized. However, as zinc porphyrins also have relatively high triplet yields, 90%, (2, 30) the similar zinc(II) octaethylporphyrin (ZnOEP) was used. We show that upconverted emission is obtained for both coordinated and noncoordinated annihilators with ZnOEP, and we also study the unwanted singlet energy transfer from anthracene back to ZnOEP. Based on the results presented here, we also discuss the limiting factors in the present coordinating annihilator–sensitizer system and, thus, highlight design criteria for future annihilator–sensitizer coordination systems.

Experimental Methods

Click to copy section linkSection link copied!
The synthetic route and detailed procedures to the new molecules Ph2–5AnPyr are described in the Supporting Information (Figure S1), including 1H and 13C NMR spectra (Figures S2–S19). Absorption spectra were recorded on a Cary 4000 spectrophotometer. The binding constants of the anthracene derivatives to ZnOEP were determined from the changes in the absorption spectra during the titration of the annihilators by performing a single value decomposition (SVD) analysis (31) in MATLAB; for details, see the Supporting Information (Figures S20–S24).
Fluorescence quantum yields were determined in dilute (32) and degassed samples relative to DPA (Φf = 1.0 in degassed toluene) (33) in 1 cm quarts cuvettes. A Spex Fluorolog τ3 spectrofluorimeter (JY Horiba) was used to record steady-state emission spectra. Fluorescence lifetimes were determined on a time-correlated single-photon counting (TCSPC) setup using a PicoQuant pulsed laser diode (377 nm) and a PMT detector (10000 peak counts in the top channel, 4096 channels) with an instrument response function fwhm of 64 ps.
Nanosecond transient absorptions measurements were performed on a home-built system with a Surelite Continuum Nd:YAG laser equipped with an OPO generating a 7 ns (fwhm), 537 nm pump beam. A quartz–halogen lamp equipped with a monochromator was used as the probe light, and a monochromator together with a five-stage PMT coupled to an oscilloscope was used for recording the transient. All photophysical measurements were carried out in analytical-grade toluene (99.99%) from Sigma-Aldrich as lower grade toluene resulted in a shift in the ZnOEP absorption similar to that of coordinated ZnOEP. Degassed samples used in the upconversion intensity study and transient absorption measurement were permanently sealed in Pyrex test tubes (d = 1 cm) after degassing following a freeze–pump–thaw procedure described in the Supporting Information.
Upconversion emission was recorded on above-mentioned Spex Fluorolog using a 532 nm green laser-pointer (Imax = 33.8 mW, A = 0.057 cm2) as the light source and a graduated neutral density filter to vary the intensity. For the viscous upconversion samples containing polystyrene a 532 nm green laser-pointer (Imax = 80 mW, A = 0.027 cm2) was used. The upconversion quantum yield (ΦUC) was determined by relative actionometry using Cresyl Violet in methanol (Φr = 0.54) (34) as the reference in accordance to eq 1(1)where Ai is the absorption at the excitation wavelength, Fi is the integrated corrected emission spectra in wavenumbers, Ii is the excitation intensity, and ηi is the refractive index of the solvent; subscripts x and r denote the sample and reference, respectively. The reference was measured at the highest excitation intensity in each measurements series. It is important to note that the maximum upconversion quantum yield is 50% as two low energy photons are consumed to produce one photon of higher energy.

Results

Click to copy section linkSection link copied!
As observed previously, extending the DPA moiety in the para-position of one of the phenyl groups only alters the absorption and fluorescence characteristics to a minor extent. (35) As seen in Figure 2, the molar absorptivity increases with more phenyl groups and a new transition at higher energies than the characteristic DPA absorption is observed for the compounds with extended phenyl groups. The fluorescence quantum yield (Φf) in toluene is high for all derivatives (Table 1), although the derivatives with extended phenyl groups have slightly lower Φf, around 0.85.
Table 1. Photophysical Properties of Coordinating Annihilators in Degassed Toluene Solutions
compdΦfτf (ns)KB (M–1)
DPA1.0 (33)6.97 (35)0
Ph1AnPyr0.96 ± 0.020 (35)5.29 ± 0.012300
Ph2AnPyr0.85 ± 0.0193.55 ± 0.015900
Ph3AnPyr0.85 ± 0.0033.17 ± 0.015800
Ph5AnPyr0.86 ± 0.0523.33 ± 0.016000
Coordination to ZnOEP was confirmed by following the shift of the ZnOEP absorption toward the red while titrating the pyridine containing derivatives, Figures S21–S24. The observed shifts were similar to that of ZnOEP with pyridine. The titration data and fitting procedure is described in the Supporting Information. KB is around 6000 M–1 for the bridged compounds Ph2AnPyr, Ph3AnPyr, and Ph5AnPyr. Ph1AnPyr with the pyridine group directly on the anthracene unit has a lower binding constant of 2300 M–1 and as expected DPA showed no coordination to ZnOEP. Coordination was also confirmed by H1 NMR spectroscopy where the anisotropic effect of the porphyrin ring-current drastically shifts the pyridine proton signals upfield (Figures S16–S19).
The sensitizer–annihilator complex lifetime could be estimated from the binding constants. Assuming a diffusion limited association constant (109 M–1 s–1), a lifetime of ∼6 μs was estimated for a binding constant of 6000 M−1 (see the Supporting Information for details). Even for a smaller assumed association constant of 108 M–1 s–1, the lifetime, ∼60 μs, is shorter than the unperturbed excited triplet state lifetimes of ZnOEP (200 μs, see Supporting Information) and anthracene derivatives. (35) With a short complex lifetime of 6–60 μs, it is likely that triplet–triplet annihilation and subsequent upconverted emission do not occur from a bound anthracene derivative. This could be beneficial as the parasitic singlet energy transfer from the upconverted anthracene singlet through FRET is distance dependent and a dissociated anthracene is, therefore, less likely to be quenched by the sensitizer.
To study the UC efficiency of the coordinating annihilators, samples were prepared with a relatively high annihilator concentration (2.5 mM) and low sensitizer concentration (1 μM) resulting in ∼90% of the sensitizer bound to an annihilator. For solubility reasons, Ph3AnPyr could only be prepared in 0.23 mM with 1 μM ZnOEP (corresponding to 67% bound sensitizer). Efficient upconverted emission, ΦUC, from 3 to 20% (Figure 3), was observed from both coordinated and noncoordinated annihilators despite the increased chance of quenching of the annihilator singlet through FRET when connecting the sensitizer and annihilator. (25-28) There can be multiple explanations for why the coordinated systems show only minor upconversion quenching through FRET, one being the weak complexation and short complex lifetime allowing the TTA step to occur between unbound (dissociated) species. Figure 3 shows the upconversion emission intensity and upconversion quantum yield (ϕUC) dependence on excitation power density.

Figure 3

Figure 3. (Left) Upconverted emission plotted against excitation power (532 nm). (Right) Upconversion quantum yield. Samples of 1 μM ZnOEP sensitizer and 2.5 mM DPA (black squares), 2.5 mM Ph1AnPyr (orange diamonds), 2.5 mM Ph2AnPyr (blue circles), 0.23 mM Ph3AnPyr (green triangles), and 2.5 mM Ph5AnPyr (red open circles).

High Resolution Image
Download MS PowerPoint Slide
A decrease in the emission was observed for Ph1AnPyr compared to DPA even though they previously have been shown to perform similarly in noncoordinating systems. (35) The reason for this can be that a small fraction of the TTA events still occur for complexed annihilators, followed by efficient singlet state quenching.
Annihilators with longer bridges (Ph2–5AnPyr) display lower UC-emission intensity, even after considering the slightly lower Φf. As TET occurs at least equally as fast as for the unbound annihilator DPA, and the longer bridges would reduce the FRET quenching compared to the shorter Ph1AnPyr annihilator (vide infra), this decrease must originate from a less efficient TTA step, indicating that not every molecular collision between two triplet annihilators results in a TTA event yielding an excited singlet. This is also supported by the fact that the annihilators Ph2–5AnPyr reach the linear upconversion regime (36) at higher excitation intensities compared to DPA and Ph1AnPyr. Also, as for Ph1AnPyr, some TTA events could occur by annihilators complexed to ZnOEP, which then would lead to quenching of the singlet excited state of the annihilator prior to emission, thus leading to a lower UC emission compared to DPA.
In an attempt to decrease the diffusion-controlled energy transfer, samples with a more viscous sample environment and low annihilator concentration were prepared. Annihilator (0.1 mM) and sensitizer (0.1 mM) were dissolved in toluene together with polystyrene (255 mg/mL, Mw = 160000 Da). However, at these low concentrations less than 5% of the sensitizer is complexed to an annihilator, assuming that the complex formation is unaffected by the addition of polystyrene. In these samples, DPA and Ph1AnPyr display similar upconversion characteristics (Figure S25). The difference between the longer bridged annihilators is also smaller compared to the more concentrated low viscosity solutions (Figure S25).

Singlet Energy Transfer

To further understand the possible energy-transfer steps in the coordinating systems, the energy-transfer efficiency from a singlet excited anthracene derivative to a nearby ZnOEP was studied. This singlet energy transfer is expected to occur through FRET, where the anthracene moiety is the donor chromophore and ZnOEP the acceptor. Thus, the energy transfer from annihilator to sensitizer can be controlled by altering the donor–acceptor distance, the relative orientation, and the spectral overlap. Our choice of an axial anthracene ligand to the ZnOEP stemmed from the close to 90° angle expected between the acceptor and donor transition dipole moments. With a binding angle of 90°, singlet energy transfer through FRET would be prevented. In addition, the distance separating the donor and acceptor plays an important role, and both of these aspects were studied closer through careful analysis of the fluorescence quenching of directly excited anthracene in the presence and absence of the porphyrin acceptor.
The fluorescence decays were recorded for the anthracene derivatives (∼15 μM) alone and for the mixture of anthracene derivative (∼15 μM) and ZnOEP (0.14 mM). From these concentrations and the binding constants, the amount of complexed anthracene was calculated to ∼40% of the total annihilator concentration. In Figure 4, the fluorescence decays of Ph5AnPyr and Ph5AnPyr–ZnOEP are shown. As seen in Figure 4, Ph5AnPyr–ZnOEP shows a biexponential decay displaying two components, one being similar to the unbound Ph5AnPyr and an initial fast decay of 152 ps. The proportion of this fast decay to the overall decay is ∼40% suggesting that FRET occurs for all coordinated Ph5AnPyr molecules. This corresponds to a transfer efficiency of 96% for the complexed annihilators. Similarly, a fast decay of 27 ps for the Ph3AnPyr–ZnOEP complex was observed, and the faster fraction here corresponded to ∼30% of the total decay, Figure S26. For the shorter bridged systems Ph2AnPyr and Ph1AnPyr higher time resolution was required, and the lifetimes for these complexes were not determined.

Figure 4

Figure 4. Upper: Fluorescence decay for Ph5AnPyr (14 μM), alone (black) corresponding fit (green), with ZnOEP (140 μM) (blue), corresponding fit (red) and instrument response function (yellow). The bump at 2 ns for Ph5AnPyr alone (black), is due to the instrument response. Lower: Residual to the fitted decays,Ph5AnPyr, alone (black) and with ZnOEP (blue).

High Resolution Image
Download MS PowerPoint Slide
The efficiency of energy transfer through FRET (ηFRET) can be calculated from the lifetime of the donor–acceptor complex (τDA) and the donor alone (τD) according to eq 2. (37)(2)The FRET energy transfer efficiency can also be determined from eq 3(3)where r is the actual distance between donor–acceptor transition dipole moments and R0 (in Å) is the characteristic distance corresponding to 50% energy transfer. R0 is calculated from spectroscopic properties of the donor and acceptor by eq 4:(4)In eq 4, κ2 is an orientation factor (vide infra), n is the refractive index, ΦD is the fluorescence quantum yield of the donor, FD is the area normalized fluorescence of the donor, ϵA is the molar absorptivity (M–1 cm–1) of the acceptor, and λ is the wavelength (nm). The integral is called the spectral overlap integral and is often denoted J. (37)
The distance r in eq 3 was determined from the Zn atom to the center of the anthracene core from AM1-optimized geometries of the complexes (Figures S27–S30). From the singlet lifetime quenching data and combining eqs 2 and 3 we determined R0, Table 2, for Ph3AnPyr and Ph5AnPyr. This in turn allows for the experimental determination of the orientation factor, κ2, from eq 4, Table 2.
Table 2. Fluorescence Lifetimes (τDA), FRET Efficiency (ηFRET), Inter-chromophore Distance (r), Förster Distance R0, Orientation Factor (κ2), and Binding Angle for Coordinated Annihilators
compdτDA (ps)ηFRET (%)ra ÅR0 (Å)⟨κ2⟩binding angleb (deg)
Ph1AnPyr<20>99.68.0   
Ph2AnPyr<20>99.412.2   
Ph3AnPyr27 ± 799.2 ± 0.217.3380.1975
Ph5AnPyr152 ± 1095.4 ± 0.325.0420.2971
a

Distance from Zn atom to center of anthracene core estimated from the AM1-optimized geometry of the complex.

b

Angle β in Figure 5.

Figure 5

Figure 5. (a) Angles between donor (blue) and acceptor (black) transition dipole moments used for calculating the orientation factor, κ2, for a donor–acceptor pair. (b) Transition dipole moment in anthracene derivatives (blue) and the degenerate transition dipole moments in ZnOEP are represented by two perpendicular transitions (green and black) spanning the porphyrin plane (orange). The y,z-plane is colored gray for clarity. Also illustrated are the angles relevant for the black transition dipole moment component in ZnOEP, β and γ. (c) As in b, now illustrating the angles relevant for the perpendicular dipole moment component (green arrow), β⊥ and γ⊥.

High Resolution Image
Download MS PowerPoint Slide
Theoretically, κ2, lies between 0 and 4 and is related to the angles between the donor and acceptor transition dipole moments as in eq 5. The angle α is the angle between the transition dipole moment of the donor and the vector connecting the transition dipole moments of the donor and acceptor; the connecting vector is here defined as the x-axis in Figure 5. The angle β is the corresponding angle for the acceptor. γ is the angle between the acceptor and donor transition dipole moments when projected in the same plane. These angles are illustrated in Figure 5a. (37, 38)(5)
As the orientation factor is dependent on the angles between the donor and acceptor chromophores, apparent binding angles between Ph3–5AnPyr and ZnOEP can be estimated from κ2, Table 2. At room temperature, the dynamic complexation results in a distribution of angles, and the apparent binding angle can be viewed as a measure on how broad this distribution is. The more the apparent angle deviates from 90° the wider the distribution.
In 9,10-substituted anthracene, the transition dipole moment for the lowest electronic transition is located along the 9,10-carbons, but for a porphyrin the transition dipole moment for the lowest singlet transition is degenerate and oriented within the molecular plane (Figure 5). To calculate κ2 for a degenerate case where there is 4-fold symmetry one can represent the degenerate transition dipole moments as two perpendicular transition dipole moments and calculate the average ⟨κ2⟩ according to eq 6 (38)(6)were κ12 is the orientation factor calculated for an arbitrarily chosen transition dipole moment in the ZnOEP plane and κ⊥2 is the orientation factor calculated for the perpendicular transition dipole moment. As can be seen in Figure 5b,c, when two perpendicular transition moment components are chosen to represent the degenerate transition one of them could be selected to lie perpendicular to the anthracene transition moment and then the other component will be defining the projection of the porphyrin plane on the anthracene transition moment (angle β).
Parts b and c of Figure 5 show the two perpendicular transition dipole moment components used here. Combining eqs 5 and 6 with the angles defined in Figure 5b,c and averaging over all azimuthal angles (i.e., rotating the porphyrin plane around the anthracene long-axis), one obtains eq 7(7)where β also corresponds to the apparent binding angle between the porphyrin plane and the annihilator transition moment. The calculated angles are 75° and 71° for Ph3AnPyr and Ph5AnPyr, respectively, Table 2. For a hypothetical binding angle of 90° no energy transfer through FRET would be observed.

Discussion

Click to copy section linkSection link copied!
First, it is interesting to examine why no notable increase in upconversion efficiency was detected in the coordinating samples. As will be discussed, this does not rule out the usefulness of coordinating the annihilator to the sensitizer in better optimized, systems. The upconversion quantum yield, ΦUC is given by the product of the quantum yield of the triplet energy transfer (ΦTET), the triplet–triplet annihilation quantum yield of forming an excited singlet annihilator (ΦTTA), the intersystem crossing yield of the sensitizer (ΦISC), and the fluorescence quantum yield of the annihilator (Φf) as in eq 8:(8)
Since ΦISC is a property of the sensitizer, we assumed it to be the same in both the coordinated and the noncoordinated system. Therefore, the difference in efficiency must be explained by either a decrease in Φf, through singlet quenching of the annihilator, by a decrease in ΦTTA or by a less efficient triplet energy transfer step, (smaller ΦTET).
Considering that the UC efficiency decreases more the longer the bridge becomes, which is opposite to the trend for Φf, and that there is a large excess of free annihilator in the samples, we conclude that the quenching of the singlet annihilator is not the main bottleneck in the present systems. We have previously shown that DPA and Ph1AnPyr have very similar UC properties when a noncoordinating sensitizer is used, (35)suggesting that a lower ΦTTA is not the explanation to the difference between these two annihilators in the current system. This leaves the triplet energy transfer as the limiting step.
We determined the rate constant for triplet energy transfer through diffusion in toluene to 7.8 × 108 M–1 s–1 (Figure S31) from nanosecond transient absorption measurements of ZnOEP and DPA, the corresponding rate constant for platinum porphyrin is in the range of 2 × 109 M–1 s–1. This can be understood by the difference in triplet state energy of the sensitizer, which is lower for ZnOEP leading to a smaller driving force for TET. The triplet energy of ZnOEP is about 1.78 eV, (39) and we estimated the triplet energy for DPA and Ph1AnPyr to 1.72 and 1.73 eV, respectively. (35) Since the singlet energy of ZnOEP is lowered upon coordination to the annihilators (vide supra) it is also likely that the triplet energy level is affected, leading to a yet smaller driving force and, thus, less efficient TET. This can, of course, be circumvented in future systems using sensitizer and annihilator pairs with better matched triplet energies.
Therefore, it is interesting to consider the case when TET is efficient, in such coordinating systems there are two possible ways of triplet energy transfer; either through the usual collisional transfer pathway or energy transfer through the bridge of the coordinating annihilator. In order to observe a difference in UC properties for the coordinating samples the triplet energy transfer must increase ΦTET due to coordination. The energy-transfer efficiency from sensitizer to annihilator can be calculated from the fraction between the sensitizer triplet lifetime in presence and absence of annihilator (eq 9)(9)where τ0 is the lifetime of the sensitizer alone and τ is the lifetime of the sensitizer in the presence of the annihilator. From the Stern–Volmer equation, the ratio of the lifetime quenching can be calculated for various annihilator concentrations(10)where kTET is the rate constant for triplet energy transfer and [A] is the annihilator concentration. If we assume that in a coordinated sensitizer–annihilator pair the triplet energy transfer is faster than the triplet excited complex dissociation and therefore quantitative we can compare the fraction of coordinated ground-state sensitizers to the diffusional triplet energy transfer efficiency, ΦTET, for various annihilator concentrations, and this is shown in Figure 6.

Figure 6

Figure 6. Calculated triplet energy transfer efficiency for diffusion-controlled energy transfer with a sensitizer lifetime of 200 μs (blue dashed) and 2 μs (blue dotted). The fraction of bound sensitizer calculated for KB = 6000 M–1 and sensitizer concentrations between 1 μM and 1 mM (black) as well as the fraction of bound sensitizer calculated for KB = 60000 M–1 and a sensitizer concentration of 1 μM (red).

High Resolution Image
Download MS PowerPoint Slide
In our present study, the maximum obtained binding constant is 6000 M–1, and in Figure 6 the fraction of bound sensitizer is shown for various sensitizer–annihilator concentrations. Compared to the diffusive energy-transfer efficiency the fraction of bound sensitizer is constantly lower. This means that, even in the case with quantitative TET in a coordination complex, no increase in ΦUC will be observed. There are two interesting conclusions from Figure 6. First, if the binding strength (KB) can be increased by a factor of 10, the static energy transfer in complexed sensitizer-annihilator pairs could compete with the diffusion limited case. This could possibly be achieved by changing to a binding group with higher affinity toward the zinc porphyrin core. Alternatively a porphyrin with another transition metal could be used which would form a stronger bond to pyridine, e.g., ruthenium porphyrins. (40) This conclusion is based on the fact that the dissociation of the excited complex is slower than the actual energy transfer and is supported by previous observations of energy and electron transfer from ruthenium and zinc porphyrins to pyridine–fullerene ligands to occur before complex dissociation. (41)
The second observation is that in the case where the sensitizer triplet lifetime is short the diffusive energy-transfer efficiency decreases markedly. This would be the case when more oxygen is present in the sample, and if the energy transfer in a coordination complex is fast, sensitization of the annihilator would be efficient even in the presence of oxygen. However, to result in TTA-UC in ambient atmosphere the rate of the TTA process must also be increased and examples of self-oriented and supramolecular structures where this is observed have been presented recently. (23, 24, 42-46) Combining sensitizer–annihilator complexes in larger supramolecular structures with increased TTA rate could therefore lead to efficient TTA-UC, possibly functioning in air.
One important optimization required for coupled sensitizer–annihilator structures is the minimization of the detrimental singlet energy transfer from the singlet excited annihilator to the sensitizer. (25-28) In our sensitizer–annihilator complexes this occurs through FRET and is therefore distance and orientation dependent, as described in eqs 3 and 4. (37)
To reduce the quenching in a FRET pair, the distance, the orientation, or the spectral overlap can be optimized. Our choice of an axial ligand was based on the close to 90° angle between the annihilator and porphyrin transition dipole moments which would attenuate the energy transfer. However, in the annihilator–sensitizer complexes presented herein efficient energy transfer to the porphyrin was still observed. One reason is the quite flexible dynamic complexation which results in an apparent binding angle of 71–75°. A stronger binding constant could also lead to a binding angle closer to 90°, but a total elimination of FRET by only increasing the binding strength is not likely.
Instead one also has to engineer the spacing between the sensitizer and the annihilator as well as the spectral overlap. Here we have studied compounds spaced from 8 to 25 Å. Extending the arm much further than 25 Å will be challenging and possibly not viable for future applications. Not only does the desired triplet energy transfer through the bridge become less efficient over longer distances but also the synthetic route becomes more demanding. Unfortunately we were not able to distinguish between any triplet energy transfer through the bridge and that occurring by normal diffusive TET either by steady state or nanosecond transient absorption measurements (Supporting Information, Figure S32).
An alternative to extending the spacing between the annihilator and sensitizer would be to use a polymeric or oligomeric annihilator structure allowing triplet migration between annihilator units with subsequent TTA further away from the sensitizer. Systems displaying triplet migration between arranged annihilators have been demonstrated recently (23, 24, 42-46) and as discussed above would also benefit the TTA, possibly resulting in TTA-UC materials functioning in air equilibrated solutions.
The spectral overlap integral, J, between the annihilators and the coordinated sensitizer is rather large in these systems, especially as coordination induces a red-shift in the ZnOEP absorption, and is determined to 1.16 × 1015 nm4 M–1 cm–1. This could be reduced substantially by either blue-shifting the porphyrin absorption by ∼20 nm or red-shifting the anthracene emission by a similar amount. We estimate the overlap integral to be reduced to in such a case, resulting in a FRET efficiency, ηFRET, of 67% in the case of a 25 Å spacer, corresponding to the Ph5AnPyr bridge. If this is combined with an orientation factor that is a tenth of that reported here for Ph5AnPyr an ηFRET of 17% would be possible.

Conclusions

Click to copy section linkSection link copied!
To conclude, we synthesized four 9,10-substituted anthracenes containing a pyridine substituent and assessed these pyridine-substituted anthracenes as annihilators in triplet–triplet annihilation upconversion (TTA-UC) systems. Using a zinc porphyrin (ZnOEP) as the sensitizer, we achieved the first sensitizer–annihilator coordination complex used for TTA-UC. We further studied the parasitic Förster resonance energy transfer from annihilator back to the sensitizer, which was found to be very efficient (>95%), contrary to what was previously observed for anthracene–Sn(IV) porphyrin systems. (29) Even though FRET was very efficient, upconverted emission was observed for all anthracene ligands.
From the findings here, we explore future design strategies for sensitizer–annihilator complexes. For one we propose that at least a 10 times stronger binding constant than the present 6000 M–1 would be necessary to achieve a reasonable sensitizer–annihilator complex concentration. We also suggest that sensitizer–annihilator coordination complexes can be beneficial in future supramolecular structures for TTA-UC functioning in air-equilibrated solutions or in solid matrices.

Supporting Information

Click to copy section linkSection link copied!

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpcc.6b06298.

  • Experimental procedures and characterization of new compounds as well as description of SVD analysis, corresponding spectroscopic data, time-resolved fluorescence, and transient absorption measurements (PDF)

Terms & Conditions

Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.

Author Information

Click to copy section linkSection link copied!
  • Corresponding Author
    • Kasper Moth-Poulsen - Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 58 Gothenburg, Sweden;  Email: [email protected]
  • Authors
    • Victor Gray - Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 58 Gothenburg, Sweden
    • Karl Börjesson - Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Gothenburg, Sweden
    • Damir Dzebo - Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 58 Gothenburg, Sweden
    • Maria Abrahamsson - Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 58 Gothenburg, Sweden
    • Bo Albinsson - Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 58 Gothenburg, Sweden
  • Notes
    The authors declare no competing financial interest.

Acknowledgment

Click to copy section linkSection link copied!

We acknowledge funding from the Swedish Energy Agency, the Swedish Research Council, the Swedish Strategic Research Council, and the Knut and Alice Walllenberg foundation.

References

Click to copy section linkSection link copied!

This article references 46 other publications.

  1. 1
    Kurreck, H.; Huber, M. Model reactions for photosynthesis-photoinduced charge and energy transfer between covalently linked porphyrin and quinone units Angew. Chem., Int. Ed. Engl. 1995, 34, 849– 866 DOI: 10.1002/anie.199508491
    Google Scholar
    There is no corresponding record for this reference.
  2. 2
    Andréasson, J.; Zetterqvist, H.; Kajanus, J.; Mårtensson, J.; Albinsson, B. Efficient non-radiative deactivation and conformational flexibility of meso-diaryloctaalkylporphyrins in the excited triplet state J. Phys. Chem. A 2000, 104, 9307– 9314 DOI: 10.1021/jp0015574
    Google Scholar
    There is no corresponding record for this reference.
  3. 3
    Islangulov, R. R.; Kozlov, D. V.; Castellano, F. N. Low power upconversion using MLCT sensitizers Chem. Commun. 2005, 1, 3776– 3778 DOI: 10.1039/b506575e
    Google Scholar
    There is no corresponding record for this reference.
  4. 4
    Baluschev, S.; Miteva, T.; Yakutkin, V.; Nelles, G.; Yasuda, a.; Wegner, G. Up-conversion fluorescence: Noncoherent excitation by sunlight Phys. Rev. Lett. 2006, 97, 7– 9 DOI: 10.1103/PhysRevLett.97.143903
    Google Scholar
    There is no corresponding record for this reference.
  5. 5
    Baluschev, S.; Yakutkin, V.; Wegner, G.; Miteva, T.; Nelles, G.; Yasuda, A.; Chernov, S.; Aleshchenkov, S.; Cheprakov, A. Upconversion with ultrabroad excitation band: Simultaneous use of two sensitizers Appl. Phys. Lett. 2007, 90, 181103 DOI: 10.1063/1.2734475
    Google Scholar
    5
    Upconversion with ultrabroad excitation band: Simultaneous use of two sensitizers
    Baluschev, S.; Yakutkin, V.; Wegner, G.; Miteva, T.; Nelles, G.; Yasuda, A.; Chernov, S.; Aleshchenkov, S.; Cheprakov, A.
    Applied Physics Letters (2007), 90 (18), 181103/1-181103/3CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)
    The authors demonstrate the ability to combine sensitizers effectively working with single emitter to increase the excitation window for noncoherent upconversion. They show effective upconversion of the red part of the sun spectrum realized by ultralow excitation intensity (≥1 W cm-2) and ultrabroad excitation spectrum (Δλ ∼80 nm).
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXlsVKrtbs%253D&md5=5d23e4aa617e9a2cb4a6247ed517e28e
  6. 6
    Islangulov, R. R.; Lott, J.; Weder, C.; Castellano, F. N. Low-power upconversion in solid polymer films J. Am. Chem. Soc. 2007, 129, 12652– 12653 DOI: 10.1021/ja075014k
    Google Scholar
    There is no corresponding record for this reference.
  7. 7
    Baluschev, S.; Yakutkin, V.; Miteva, T.; Wegner, G.; Roberts, T.; Nelles, G.; Yasuda, A.; Chernov, S.; Aleshchenkov, S.; Cheprakov, A. A general approach for non-coherently excited annihilation up-conversion: Transforming the solar-spectrum New J. Phys. 2008, 10, 013007 DOI: 10.1088/1367-2630/10/1/013007
    Google Scholar
    There is no corresponding record for this reference.
  8. 8
    Singh-Rachford, T. N.; Castellano, F. N. Low Power Visible-to-UV Upconversion J. Phys. Chem. A 2009, 113, 5912– 5917 DOI: 10.1021/jp9021163
    Google Scholar
    8
    Low Power Visible-to-UV Upconversion
    Singh-Rachford, Tanya N.; Castellano, Felix N.
    Journal of Physical Chemistry A (2009), 113 (20), 5912-5917CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    Low power visible-to-UV photon upconversion is demonstrated for the 1st time, achieved from 2 simple org. chromophores dissolved in benzene. Selective 442 nm excitation of the triplet sensitizer 2,3-butanedione (biacetyl) in the presence of the laser dye 2,5-diphenyloxazole (PPO) results in the observation of singlet fluorescence from the latter in the UV centered at 360 nm, anti-Stokes shifted by a record 0.64 eV with respect to the excitation. All of the exptl. data are consistent with the upconverted singlet PPO fluorescence being produced as a result of biacetyl-sensitized triplet-triplet annihilation (TTA) of triplet excited PPO chromophores. Nanosecond laser flash photolysis performed under pseudo-first-order conditions revealed the bimol. rate const. of triplet-triplet energy transfer between the biacetyl sensitizer and PPO acceptor, kq = 9.0 × 108 M-1s-1. The TTA process was confirmed by the quadratic dependence of the upconverted integrated PPO emission intensity measured with respect to incident 442 nm light power d. The max. quantum yield of the upconverted emission (0.0058 ± 0.0002) was detd. relative to 1,8-diphenyl-1,3,5,7-octatetraene, both measured with 0.389 W/cm2 incident power d. The PPO triplet-triplet annihilation rate const. (kTT) was detd. from transient absorption decays monitored at the peak of its characteristic triplet-to-triplet excited-state absorption (500 nm) as a function of incident pulsed laser fluence; this process attains the diffusion limit in benzene at room temp., kTT = 1.1 ± 0.1 × 1010 M-1 s-1.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXltVCnt78%253D&md5=e767b7271fea77f93956e8404ed01ca2
  9. 9
    Ji, S.; Wu, W.; Wu, W.; Guo, H.; Zhao, J. Ruthenium(II) polyimine complexes with a long-lived 3IL excited state or a 3MLCT/3IL equilibrium: Efficient triplet sensitizers for low-power upconversion Angew. Chem., Int. Ed. 2011, 50, 1626– 1629 DOI: 10.1002/anie.201006192
    Google Scholar
    9
    Ruthenium(II) polyimine complexes with a long-lived 3IL excited state or a 3MLCT/3IL equilibrium: efficient triplet sensitizers for low-power upconversion
    Ji, Shaomin; Wu, Wanhua; Wu, Wenting; Guo, Huimin; Zhao, Jianzhang
    Angewandte Chemie, International Edition (2011), 50 (7), 1626-1629, S1626/1-S1626/7CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
    TTA (triplet-triplet annihilation)-based upconversion was achieved by using a Ru(II) complex with a long-lived 3IL (intraligand) excited state. The results indicated that the 3IL excited state is much more efficient in sensitizing the TTA-based upconversion than the 3MLCT excited states.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhslygs7w%253D&md5=52704f2dbf62333bb2624ddb235cc307
  10. 10
    Trupke, T.; Green, M. A.; Würfel, P. Improving solar cell efficiencies by up-conversion of sub-band-gap light J. Appl. Phys. 2002, 92, 4117– 4122 DOI: 10.1063/1.1505677
    Google Scholar
    10
    Improving solar cell efficiencies by up-conversion of sub-band-gap light
    Trupke, T.; Green, M. A.; Wurfel, P.
    Journal of Applied Physics (2002), 92 (7), 4117-4122CODEN: JAPIAU; ISSN:0021-8979. (American Institute of Physics)
    A system for solar energy conversion using the up-conversion of sub-band-gap photons to increase the max. efficiency of a single-junction conventional, bifacial solar cell is discussed. An up-converter is located behind a solar cell and absorbs transmitted sub-band-gap photons via sequential ground state absorption/excited state absorption processes in a three-level system. This generates an excited state in the up-converter from which photons are emitted which are subsequently absorbed in the solar cell and generate electron-hole pairs. The solar energy conversion efficiency of this system in the radiative limit is calcd. for different cell geometries and different illumination conditions using a detailed balance model. It is shown that in contrast to an impurity photovoltaic solar cell the conditions of photon selectivity and of complete absorption of high-energy photons can be met simultaneously in this system by restricting the widths of the bands in the up-converter. The upper limit of the energy conversion efficiency of the system is found to be 63.2% for concd. sunlight and 47.6% for nonconcd. sunlight.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XntF2msLc%253D&md5=0b7cc42919c3bec2316a39bb2a6fc9af
  11. 11
    Ekins-Daukes, N. J.; Schmidt, T. W. A molecular approach to the intermediate band solar cell: The symmetric case Appl. Phys. Lett. 2008, 93, 063507 DOI: 10.1063/1.2970157
    Google Scholar
    11
    A molecular approach to the intermediate band solar cell: The symmetric case
    Ekins-Daukes, N. J.; Schmidt, T. W.
    Applied Physics Letters (2008), 93 (6), 063507/1-063507/3CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)
    Mol. materials may overcome some of the difficulties for making an intermediate band solar cell by storing energy in long-lived triplet states. Both the problems of fast nonradiative interband relaxation and selective photon absorption can be solved by this approach. A practical implementation of the mol. intermediate band solar cell is considered with a sym. band alignment, resting on a proven triplet-triplet annihilation process. The limiting power conversion efficiency for this system exceeds that of a single bandgap device over a broad range, peaking at 40.6% for 1.9 eV under 1 sun illumination. (c) 2008 American Institute of Physics.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtVSjsb7O&md5=9acd4de681b78adeb94de447df8a84ab
  12. 12
    de Wild, J.; Meijerink, A.; Rath, J. K.; van Sark, W. G. J. H. M.; Schropp, R. E. I. Upconverter solar cells: materials and applications Energy Environ. Sci. 2011, 4, 4835 DOI: 10.1039/c1ee01659h
    Google Scholar
    12
    Upconverter solar cells: materials and applications
    de Wild, J.; Meijerink, A.; Rath, J. K.; van Sark, W. G. J. H. M.; Schropp, R. E. I.
    Energy & Environmental Science (2011), 4 (12), 4835-4848CODEN: EESNBY; ISSN:1754-5706. (Royal Society of Chemistry)
    A review. Spectral conversion of sunlight is a promising route to reduce spectral mismatch losses that are responsible for the major part of the efficiency losses in solar cells. Both upconversion and down conversion materials are presently explored. In an upconversion process, photons with an energy lower than the band gap of the solar cell are converted to higher energy photons. These higher photons are directed back to the solar cell and absorbed, thus increasing the efficiency. Different types of up converter materials are investigated, based on luminescent ions or org. mols. Proof of principle expts. with lanthanide ion based up converters have indicated that the benefit of an upconversion layer is limited by the high light intensities needed to reach high upconversion quantum efficiencies. To address this limitation, up converter materials may be combined with quantum dots or plasmonic particles to enhance the upconversion efficiency and improve the feasibility of applying up converters in com. solar cells.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFKlurbL&md5=b81db4a8a8c0494fd1e10c9a3be8e3eb
  13. 13
    Briggs, J. a.; Atre, A. C.; Dionne, J. a. Narrow-bandwidth solar upconversion: Case studies of existing systems and generalized fundamental limits J. Appl. Phys. 2013, 113, 124509 DOI: 10.1063/1.4796092
    Google Scholar
    13
    Narrow-bandwidth solar upconversion: Case studies of existing systems and generalized fundamental limits
    Briggs, Justin A.; Atre, Ashwin C.; Dionne, Jennifer A.
    Journal of Applied Physics (Melville, NY, United States) (2013), 113 (12), 124509/1-124509/5CODEN: JAPIAU; ISSN:0021-8979. (American Institute of Physics)
    Upconversion of sub-bandgap photons is a promising approach to exceed the Shockley-Queisser limit in solar technologies. Calcns. have indicated that ideal, upconverter-enhanced cell efficiencies can exceed 44% for non-concd. sunlight, but such improvements have yet to be obsd. exptl. To explain this discrepancy, a thermodn. model is developed of an upconverter-cell considering a highly realistic narrow-band, non-unity-quantum-yield upconverter. As expected, solar cell efficiencies increase with increasing upconverter bandwidth and quantum yield, with max. efficiency enhancements found for near-IR upconverter absorption bands. The model indicates that existing bimol. and lanthanide-based upconverters will not improve cell efficiencies more than 1%, consistent with recent expts. However, the calcns. show that these upconverters can significantly increase cell efficiencies from 28-34% with improved quantum yield, despite their narrow bandwidths. The results highlight the interplay of absorption and quantum yield in upconversion, and provide a platform for optimizing future solar upconverter designs. (c) 2013 American Institute of Physics.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXltVelt7o%253D&md5=a6a2dfb27edcc7ebc091f1cce7fdd6e8
  14. 14
    Cheng, Y. Y.; Fückel, B.; MacQueen, R. W.; Khoury, T.; Clady, R. G. C. R.; Schulze, T. F.; Ekins-Daukes, N. J.; Crossley, M. J.; Stannowski, B.; Lips, K. Improving the light-harvesting of amorphous silicon solar cells with photochemical upconversion Energy Environ. Sci. 2012, 5, 6953 DOI: 10.1039/c2ee21136j
    Google Scholar
    14
    Improving the light-harvesting of amorphous silicon solar cells with photochemical upconversion
    Cheng, Yuen Yap; Fueckel, Burkhard; MacQueen, Rowan W.; Khoury, Tony; Clady, Raphael G. C. R.; Schulze, Tim F.; Ekins-Daukes, N. J.; Crossley, Maxwell J.; Stannowski, Bernd; Lips, Klaus; Schmidt, Timothy W.
    Energy & Environmental Science (2012), 5 (5), 6953-6959CODEN: EESNBY; ISSN:1754-5706. (Royal Society of Chemistry)
    Single-threshold solar cells are fundamentally limited by their ability to harvest only those photons above a certain energy. Harvesting below-threshold photons and re-radiating this energy at a shorter wavelength would thus boost the efficiency of such devices. We report an increase in light harvesting efficiency of a hydrogenated amorphous silicon (a-Si:H) thin-film solar cell due to a rear up-converter based on sensitized triplet-triplet-annihilation in org. mols. Low energy light in the range 600-750 nm is converted to 550-600 nm light due to the incoherent photochem. process. A peak efficiency enhancement of (1.0 ± 0.2)% at 720 nm is measured under irradn. equiv. to (48 ± 3) suns (AM1.5). We discuss the pathways to be explored in adapting photochem. UC for application in various single threshold devices.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XmsVWqsbk%253D&md5=0c6c2f1c6335ecc9a5e4a7458c648eb9
  15. 15
    Schulze, T. F.; Cheng, Y. Y.; Fuckel, B.; MacQueen, R. W.; Danos, A.; Davis, N. J. L. K.; Tayebjee, M. J. Y.; Khoury, T.; Clady, R. G. C. R.; Ekins-Daukes, N. J. Photochemical upconversion enhanced solar cells: Effect of a back reflector Aust. J. Chem. 2012, 65, 480– 485 DOI: 10.1071/CH12117
    Google Scholar
    15
    Photochemical Upconversion Enhanced Solar Cells: Effect of a Back Reflector
    Schulze, Tim F.; Cheng, Yuen Yap; Fueckel, Burkhard; MacQueen, Rowan W.; Danos, Andrew; Davis, Nathaniel J. L. K.; Tayebjee, Murad J. Y.; Khoury, Tony; Clady, Raphael G. C. R.; Ekins-Daukes, N. J.; Crossley, Maxwell J.; Stannowski, Bernd; Lips, Klaus; Schmidt, Timothy W.
    Australian Journal of Chemistry (2012), 65 (5), 480-485CODEN: AJCHAS; ISSN:0004-9425. (CSIRO Publishing)
    Photochem. upconversion is applied to a hydrogenated amorphous silicon solar cell in the presence of a back-scattering layer. A custom-synthesized porphyrin was utilized as the sensitizer species, with rubrene as the emitter. Under a bias of 24 suns, a peak external quantum efficiency (EQE) enhancement of ∼ 2% was obsd. at a wavelength of 720 nm. Without the scattering layer, the EQE enhancement was half this value, indicating that the effect of the back-scatterer is to double the efficacy of the upconverting device. The results represent an upconversion figure of merit of 3.5 × 10-4 mAcm-2 sun-2, which is the highest reported to date.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xns1yrsL4%253D&md5=9424f0614d3a4c9daa288e65188b3dc8
  16. 16
    Schulze, T. F.; Czolk, J.; Cheng, Y.-Y.; Fückel, B.; MacQueen, R. W.; Khoury, T.; Crossley, M. J.; Stannowski, B.; Lips, K.; Lemmer, U. Efficiency Enhancement of Organic and Thin-Film Silicon Solar Cells with Photochemical Upconversion J. Phys. Chem. C 2012, 116, 22794– 22801 DOI: 10.1021/jp309636m
    Google Scholar
    16
    Efficiency enhancement of organic and thin-film silicon solar cells with photochemical upconversion
    Schulze, Tim F.; Czolk, Jens; Cheng, Yuen-Yap; Fuckel, Burkhard; MacQueen, Rowan W.; Khoury, Tony; Crossley, Maxwell J.; Stannowski, Bernd; Lips, Klaus; Lemmer, Uli; Colsmann, Alexander; Schmidt, Timothy W.
    Journal of Physical Chemistry C (2012), 116 (43), 22794-22801CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
    The efficiency of thin-film solar cells with large optical band gaps, such as org. bulk heterojunction or amorphous silicon solar cells, is limited by their inability to harvest the (infra)red part of the solar spectrum. Photochem. upconversion based on triplet-triplet annihilation (TTA-UC) can potentially boost those solar cells by absorbing sub-bandgap photons and coupling the upconverted light back into the solar cell in a spectral region that the cell can efficiently convert into elec. current. In the present study we augment two types of org. solar cells and one amorphous silicon (a-Si:H) solar cell with a TTA-upconverter, demonstrating a solar cell photocurrent increase of up to 0.2% under a moderate concn. (19 suns). The behavior of the org. solar cells, whose augmentation with an upconverting device is so-far unreported, is discussed in comparison to a-Si:H solar cells. Furthermore, on the basis of the TTA rate equations and optical simulations, we assess the potential of TTA-UC augmented solar cells and highlight a strategy for the realization of a device-relevant current increase by TTA-upconversion.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhsVGju7nN&md5=9966a864ffbfdf354950906d44eacf7f
  17. 17
    Kim, J.-h.; Kim, J.-h. Encapsulated TTA-Based Upconversion in the Aqueous Phase for Sub-bandgap Semiconductor Photocatalysis Encapsulated TTA-Based Upconversion in the Aqueous Phase for Sub-bandgap Semiconductor Photocatalysis J. Am. Chem. Soc. 2012, 134, 17478– 17481 DOI: 10.1021/ja308789u
    Google Scholar
    There is no corresponding record for this reference.
  18. 18
    Khnayzer, R. S.; Blumhoff, J.; Harrington, J. a.; Haefele, A.; Deng, F.; Castellano, F. N. Upconversion-powered photoelectrochemistry Chem. Commun. 2012, 48, 209 DOI: 10.1039/C1CC16015J
    Google Scholar
    18
    Upconversion of sub-band gap light in solar cell; powered photoelectrochemistry, WO3 nanostructured anode
    Khnayzer, Rony S.; Blumhoff, Joerg; Harrington, Jordan A.; Haefele, Alexandre; Deng, Fan; Castellano, Felix N.
    Chemical Communications (Cambridge, United Kingdom) (2012), 48 (2), 209-211CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
    Upconversion photochem. occurring between palladium II, octaethylporphyrin (PdOEP) and 9,10-diphenylanthracene (DPA) in toluene successfully sensitizes nanostructured WO3 photoanodes (Eg = 2.7 eV) to sub-bandgap non-coherent green photons at low power d.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFGqurfI&md5=624a1edd856e90dc0a789d6fe2e7d9b6
  19. 19
    Nattestad, A.; Cheng, Y.; Macqueen, R.; Schulze, T.; Thompson, F.; Mozer, A.; Fuckel, B.; Khoury, T.; Crossley, M.; Lips, K. Dye-Sensitized Solar Cell with Integrated Triplet Triplet Annihilation Upconversion System J. Phys. Chem. Lett. 2013, 4, 2073– 2078 DOI: 10.1021/jz401050u
    Google Scholar
    19
    Dye-Sensitized Solar Cell with Integrated Triplet-Triplet Annihilation Upconversion System
    Nattestad, Andrew; Cheng, Yuen Yap; MacQueen, Rowan W.; Schulze, Tim F.; Thompson, Fletcher W.; Mozer, Attila J.; Fuckel, Burkhard; Khoury, Tony; Crossley, Maxwell J.; Lips, Klaus; Wallace, Gordon G.; Schmidt, Timothy W.
    Journal of Physical Chemistry Letters (2013), 4 (12), 2073-2078CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
    Photon upconversion (UC) by triplet-triplet annihilation (TTA-UC) is employed to enhance the response of solar cells to sub-bandgap light. Here, the authors present the 1st report of an integrated photovoltaic device, combining a dye-sensitized solar cell (DSC) and TTA-UC system. The integrated device displays enhanced current under sub-bandgap illumination, resulting in a figure of merit (FoM) under low concn. (3 suns), which is competitive with the best values recorded to date for non-integrated systems. Thus, the authors demonstrate both the compatibility of DSC and TTA-UC and a viable method for device integration.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXptVChsL4%253D&md5=dad3b46ae336db267476b18169e6198b
  20. 20
    Börjesson, K.; Dzebo, D.; Albinsson, B.; Moth-Poulsen, K. Photon upconversion facilitated molecular solar energy storage J. Mater. Chem. A 2013, 1, 8521– 8524 DOI: 10.1039/c3ta12002c
    Google Scholar
    There is no corresponding record for this reference.
  21. 21
    Gray, V.; Dzebo, D.; Abrahamsson, M.; Albinsson, B.; Moth-Poulsen, K. Triplet-triplet annihilation photon-upconversion: towards solar energy applications Phys. Chem. Chem. Phys. 2014, 16, 10345– 52 DOI: 10.1039/c4cp00744a
    Google Scholar
    21
    Triplet-triplet annihilation photon-upconversion: towards solar energy applications
    Gray, Victor; Dzebo, Damir; Abrahamsson, Maria; Albinsson, Bo; Moth-Poulsen, Kasper
    Physical Chemistry Chemical Physics (2014), 16 (22), 10345-10352CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
    Solar power prodn. and solar energy storage are important research areas for development of technologies that can facilitate a transition to a future society independent of fossil fuel based energy sources. Devices for direct conversion of solar photons suffer from poor efficiencies due to spectrum losses, which are caused by energy mismatch between the optical absorption of the devices and the broadband irradn. provided by the sun. In this context, photon-upconversion technologies are becoming increasingly interesting since they might offer an efficient way of converting low energy solar energy photons into higher energy photons, ideal for solar power prodn. and solar energy storage. This perspective discusses recent progress in triplet-triplet annihilation (TTA) photon-upconversion systems and devices for solar energy applications. Furthermore, challenges with evaluation of the efficiency of TTA-photon-upconversion systems are discussed and a general approach for evaluation and comparison of existing systems is suggested.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXotFWhsb0%253D&md5=111a2d4f5eb9b403c256ba5b35255de9
  22. 22
    Yanai, N.; Kimizuka, N. Recent emergence of photon upconversion based on triplet energy migration in molecular assemblies Chem. Commun. 2016, 52, 5354– 5370 DOI: 10.1039/C6CC00089D
    Google Scholar
    22
    Recent emergence of photon upconversion based on triplet energy migration in molecular assemblies
    Yanai, Nobuhiro; Kimizuka, Nobuo
    Chemical Communications (Cambridge, United Kingdom) (2016), 52 (31), 5354-5370CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
    A review. An emerging field of triplet energy migration-based photon upconversion (TEM-UC) is reviewed. Highly efficient photon upconversion has been realized in a wide range of chromophore assemblies, such as non-solvent liqs., ionic liqs., amorphous solids, gels, supramol. assemblies, mol. crystals, and metal-org. frameworks (MOFs). The control over their assembly structures allows for unexpected air-stability and max. upconversion quantum yield at weak solar irradiance that has never been achieved by the conventional mol. diffusion-based mechanism. The introduction of the "self-assembly" concept offers a new perspective in photon upconversion research and triplet exciton science, which show promise for numerous applications ranging from solar energy conversion to chem. biol.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XjslGmur8%253D&md5=4d22fb497b090044c2914ffe081356db
  23. 23
    Mahato, P.; Monguzzi, A.; Yanai, N.; Yamada, T.; Kimizuka, N. Fast and long-range triplet exciton diffusion in metalorganic frameworks for photon upconversion at ultralow excitation power Nat. Mater. 2015, 14, 924– 930 DOI: 10.1038/nmat4366
    Google Scholar
    There is no corresponding record for this reference.
  24. 24
    Mahato, P.; Yanai, N.; Sindoro, M.; Granick, S.; Kimizuka, N. Preorganized Chromophores Facilitate Triplet Energy Migration, Annihilation and Upconverted Singlet Energy Collection J. Am. Chem. Soc. 2016, 138, 6541– 6549 DOI: 10.1021/jacs.6b01652
    Google Scholar
    There is no corresponding record for this reference.
  25. 25
    Kozlov, D. V.; Castellano, F. N. Anti-Stokes delayed fluorescence from metal organic bichromophores Chem. Commun. 2004, 1, 2860– 2861 DOI: 10.1039/B412681E
    Google Scholar
    There is no corresponding record for this reference.
  26. 26
    Bergamini, G.; Ceroni, P.; Fabbrizi, P.; Cicchi, S. A multichromophoric dendrimer: from synthesis to energy up-conversion in a rigid matrix Chem. Commun. 2011, 47, 12780 DOI: 10.1039/c1cc16000a
    Google Scholar
    26
    A multichromophoric dendrimer: from synthesis to energy up-conversion in a rigid matrix
    Bergamini, Giacomo; Ceroni, Paola; Fabbrizi, Pierangelo; Cicchi, Stefano
    Chemical Communications (Cambridge, United Kingdom) (2011), 47 (48), 12780-12782CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
    A dendrimer (I) with a [Ru(bpy)3]2+ (bpy = 2,2'-bipyridine) complex as a core and four diphenylanthracene units at the periphery was prepd. from a scaffold based on a bipyridyl ligand bearing four terminal alkyne groups. Upon green light excitation, the dendrimer shows blue luminescence even in a rigid matrix at 77 K thanks to the dendritic multichromophoric structure.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFamsLfI&md5=3645f0e78f33358e9efe7a8427fa9ab7
  27. 27
    Tilley, A. J.; Kim, M. J.; Chen, M.; Ghiggino, K. P. Photo-induced energy transfer in ruthenium-centred polymers prepared by a RAFT approach Polymer 2013, 54, 2865– 2872 DOI: 10.1016/j.polymer.2013.03.064
    Google Scholar
    27
    Photo-induced energy transfer in ruthenium-centered polymers prepared by a RAFT approach
    Tilley, Andrew J.; Kim, Min Jeong; Chen, Ming; Ghiggino, Kenneth P.
    Polymer (2013), 54 (12), 2865-2872CODEN: POLMAG; ISSN:0032-3861. (Elsevier Ltd.)
    Triplet and singlet excitation energy transfer processes are investigated in two novel di- and hexa-functionalized ruthenium centered polymers prepd. by RAFT methods. The polymers consist of a ruthenium tris-bipyridyl ligand complex (Ru(bpy)3) core and pendant polymer 'arms' of 9,10-diphenylanthracene (DPA). Steady state and transient emission and absorption expts. are used to investigate intramol. energy transfer processes following photoexcitation of Ru(bpy)3 and DPA. Triplet energy transfer from the Ru(bpy)3 core to pendant DPA chromophores in the polymer arms is more efficient than the reverse singlet energy transfer process, attributed in part to the long triplet lifetime of Ru(bpy)3 and the polymer structure. A consequence is that intra-polymer chain triplet energy transfer from Ru(bpy)3 to DPA chromophores followed by triplet-triplet annihilation and delayed fluorescence from the DPA can be obsd.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXmtlejur0%253D&md5=4233b8623d180c78553ee05d8f56583f
  28. 28
    Yu, S.; Zeng, Y.; Chen, J.; Yu, T.; Zhang, X.; Yang, G.; Li, Y. Intramolecular triplet-triplet energy transfer enhanced triplet-triplet annihilation upconversion with a short-lived triplet state platinum(II) terpyridyl acetylide photosensitizer RSC Adv. 2015, 5, 70640– 70648 DOI: 10.1039/C5RA12579K
    Google Scholar
    28
    Intramolecular triplet-triplet energy transfer enhanced triplet-triplet annihilation upconversion with a short-lived triplet state platinum(II) terpyridyl acetylide photosensitizer
    Yu, Shuai; Zeng, Yi; Chen, Jinping; Yu, Tianjun; Zhang, Xiaohui; Yang, Guoqiang; Li, Yi
    RSC Advances (2015), 5 (86), 70640-70648CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)
    A model of a dendritic compd. (Pt-DPA) with two Pt-complex photosensitizer chromophores and two 9,10-diphenylanthracene (DPA) acceptor groups covalently attached to the periphery and the core of the poly(aryl ether) dendrimer of generation 1 was prepd. A triplet-triplet annihilation upconversion (TTA-UC) system (Pt-DPA/DPA-OH) was constructed in deaerated DMF by combining Pt-DPA with a dissociative acceptor (DPA-OH). Although the lifetime of the triplet state of the Pt-complex is only 52 ns, the upconversion fluorescence from DPA (400-460 nm) in the Pt-DPA/DPA-OH system was obsd. with a quantum yield of 0.22% upon selective excitation of the Pt-complex with a 473 nm laser, which is due to the efficient intramol. triplet-triplet energy transfer (ΦTTET > 0.81) from the Pt-complex photosensitizer to the DPA acceptor within Pt-DPA. The acceptor covalently linked with the photosensitizer acts as an energy-relay to transfer the harvested energy to the dissociative acceptor which further undergoes the TTA process. The efficient intramol. triplet-triplet energy transfer process between the photosensitizer and the acceptor plays an important role in the TTA-UC system building with a short-lived triplet state photosensitizer, which facilitates the prodn. of the triplet state of the acceptor, thus advancing the TTA-UC process. This work presents a new strategy for construction of efficient TTA-UC systems utilizing short-lived triplet state photosensitizers.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlajurvO&md5=51ba7cfcbef5a9b963f5d9c5563a951f
  29. 29
    Giribabu, L.; Ashok Kumar, A.; Neeraja, V.; Maiya, B. G. Orientation Dependence of Energy Transfer in an Anthracene-Porphyrin Donor-Acceptor System Angew. Chem. 2001, 113, 3733– 3736 DOI: 10.1002/1521-3757(20011001)113:19<3733::AID-ANGE3733>3.0.CO;2-J
    Google Scholar
    There is no corresponding record for this reference.
  30. 30
    Harriman, A.; Porter, G.; Richoux, M.-C. Photosensitised reduction of water to hydrogen using water-soluble zinc porphyrins J. Chem. Soc., Faraday Trans. 2 1981, 77, 833 DOI: 10.1039/f29817700833
    Google Scholar
    30
    Photosensitized reduction of water to hydrogen using water-soluble zinc porphyrins
    Harriman, Anthony; Porter, George; Richoux, Marie Claude
    Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics (1981), 77 (5), 833-44CODEN: JCFTBS; ISSN:0300-9238.
    The report that a pos. charged, H2O-sol. Zn porphyrin photosensitizers the redn. of H2O to H2 with high efficiency (Kalanasundaram, K.; Gratzel, M., 1980) was confirmed. Using Me viologen as electron relay and EDTA as sacrificial donor, the quantum yield (.vphi.) for prodn. of 1/2H2 is ∼0.6. The reaction mechanism involves redn. of Me viologen by triplet porphyrin, the porphyrin π-radical cation being reduced by EDTA. Optimization of the concns. of the reactants for increased prodn. of H2 and limited destruction of porphyrin gave a turnover with respect to the porphyrin of ≤6000. Ways of improving .vphi. and of increasing the fraction of sunlight harvested were considered. The porphyrin π-radical cation may possess the thermodn. capacity to oxidize water to O2.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL3MXktlWjsrk%253D&md5=f5056890e9fa0c2e9f411c6e945fc70b
  31. 31
    Kubista, M.; Sjoback, R.; Albinsson, B. Determination of Equilibrium Constants by chemometric Analysis of Spectroscopic Data Anal. Chem. 1993, 65, 994– 998 DOI: 10.1021/ac00056a008
    Google Scholar
    There is no corresponding record for this reference.
  32. 32
    Crosby, G. A.; Demas, J. N. The Measurement of Photoluminescence Quantum Yields. A Review J. Phys. Chem. 1971, 75, 991– 1024 DOI: 10.1021/j100678a001
    Google Scholar
    32
    Measurement of photoluminescence quantum yields. Review
    Crosby, Glenn A.; Demas, James N.
    Journal of Physical Chemistry (1971), 75 (8), 991-1024CODEN: JPCHAX; ISSN:0022-3654.
    A review is given with 147 refs. Methods and apparatus for measuring photoluminescence quantum yields, standards, apparatus calibration, and data corrections are described.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE3MXktFamsL4%253D&md5=5d93e40ea597072c98ab7f195f9cac08
  33. 33
    Heinrich, G.; Schoof, S.; Gusten, H. 9,10-diphenylanthracene as fluorescence quantum yield standard J. Photochem. 1974, 3, 315– 320 DOI: 10.1016/0047-2670(74)80040-7
    Google Scholar
    33
    9,10-Diphenylanthracene as fluorescence quantum yield standard
    Heinrich, G.; Schoof, S.; Gusten, H.
    Journal of Photochemistry (1974), 3 (4), 315-20CODEN: JPCMAE; ISSN:0047-2670.
    The effect of solvent (Me2CO, C6H6, CHCl3, cyclohexane, Et2O + isopentane + EtOH 5:5:2 by vol (EPA), EtOH, AcOEt, iso-BuOH, isopentane, kerosine, paraffin, petroleum ether, poly(Me methacrylate), and PhMe) and temp. 77-333° K.) on the fluorescent quantum yield from 9,10-diphenylathracene (I) (<10-4 M, degassed) are summarized. The fluorescence decay times, fluorescence quantum yields, triplet-triplet absorption wavelengths, and triplet decay times were detd. for I in soln. in n-C7H16 (298° K), EtOH (77 and 298° K.), C6H6 (198° K.), cyclohexane (298° K.), and EPA (77 and 298° K.). It is 1.00 in all but n-heptane (0.89), EtOH at 298° K. (0.94), and C6H6 (0.96). Quinine sulfate at 25° has a quantum yield of 0.55.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE2MXhtlWnurg%253D&md5=eb96bc45e63a64970d06165bce64fccd
  34. 34
    Magde, D.; Brannon, J. H.; Cremers, T. L.; Olmsted, J. Absolute luminescence yield of cresyl violet. A standard for the red J. Phys. Chem. 1979, 83, 696– 699 DOI: 10.1021/j100469a012
    Google Scholar
    34
    Absolute luminescence yield of cresyl violet. A standard for the red
    Magde, Douglas; Brannon, James H.; Cremers, Teresa L.; Olmsted, John, III
    Journal of Physical Chemistry (1979), 83 (6), 696-9CODEN: JPCHAX; ISSN:0022-3654.
    The Φf for the oxazine dye cresyl violet is 0.545 in MeOH, at 22 °, for excitation from 540 to 640 nm. With a mean emission wavelength near 638 nm, this should be a useful luminescence quantum yield std. for the red. The abs. accuracy is well within 10% and probably better than 5%. The yield is rather insensitive to conditions even including choice of solvent. It is const. from extreme diln. up to above 10-4 M; but absorption-emission overlap makes it a convenient std. only for relative measurements which use 'dil.' procedures. Two independent and completely different calorimetric methods were used to achieve an abs. measurement which is independent of all previous luminescence yield data: photomicrocalorimetry, an optimized conventional technique, and thermal blooming, a new laser approach.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE1MXhsVeksrw%253D&md5=a0d78bf8219b64c1ad0f768fd5dd2257
  35. 35
    Gray, V.; Dzebo, D.; Lundin, A.; Alborzpour, J.; Abrahamsson, M.; Albinsson, B.; Moth-Poulsen, K. Photophysical characterization of the 9,10-disubstituted anthracene chromophore and its applications in triplet triplet annihilation photon upconversion J. Mater. Chem. C 2015, 3, 11111– 11121 DOI: 10.1039/C5TC02626A
    Google Scholar
    35
    Photophysical characterization of the 9,10-disubstituted anthracene chromophore and its applications in triplet-triplet annihilation photon upconversion
    Gray, Victor; Dzebo, Damir; Lundin, Angelica; Alborzpour, Jonathan; Abrahamsson, Maria; Albinsson, Bo; Moth-Poulsen, Kasper
    Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2015), 3 (42), 11111-11121CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)
    Mols. based on anthracene are commonly used in applications such as OLEDs and triplet-triplet annihilation upconversion. In future design of blue emitting materials it is useful to know which part of the mol. can be altered to obtain new phys. properties without losing the inherent optical properties. We have studied the effect of substitution of 9,10-substituted anthracenes. Eight anthracenes with arom. Ph and thiophene substituents were synthesized, contg. both electron donating and accepting groups. The substitutions were found to affect the UV/Vis absorption only to a small extent, however the fluorescence properties were more affected with the thiophene substituents that decreased the fluorescence quantum yield from unity to <10%. DFT calcns. confirm the minor change in absorption and indicate that the first and second triplet state energies are also unaffected. Finally the three most fluorescent derivs. 4-(10-phenylanthracene-9-yl)pyridine, 9-phenyl-10-(4-(trifluoromethyl)phenyl)anthracene and 4-(10-phenylanthracene-9-yl)benzonitrile were successfully utilized as annihilators in a triplet-triplet annihilation upconversion (TTA-UC) system employing platinum octaethylporphyrin as the sensitizer. The obsd. upconversion quantum yields, .vphi.UC, slightly exceeded that of the benchmark annihilator 9,10-diphenylanthracene (DPA).
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhsFamtrnF&md5=4480fc4d27e7996ea00566aed2cc235c
  36. 36
    Haefele, A.; Blumhoff, J.; Khnayzer, R. S.; Castellano, F. N. Getting to the (Square) root of the problem: How to make noncoherent pumped upconversion linear J. Phys. Chem. Lett. 2012, 3, 299– 303 DOI: 10.1021/jz300012u
    Google Scholar
    36
    Getting to the (Square) Root of the Problem: How to Make Noncoherent Pumped Upconversion Linear
    Haefele, Alexandre; Blumhoff, Jorg; Khnayzer, Rony S.; Castellano, Felix N.
    Journal of Physical Chemistry Letters (2012), 3 (3), 299-303CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
    The authors present exptl. data illustrating that photochem. upconversion based on sensitized triplet-triplet annihilation can exhibit anti-Stokes emissions whose intensities with respect to the excitation power can vary between quadratic and linear using a noncoherent polychromatic light source. The benchmark upconverting compn. consisting of Pd(II) octaethylporphyrin (PdOEP) sensitizers and 9,10-diphenylanthracene (DPA) acceptors/annihilators in toluene was selected to generate quadratic, intermediate, and linear behavior under both coherent and noncoherent excitation conditions. Each of these power laws was traversed in a single sample in 1 contiguous expt. through selective pumping of the sensitizer using an Ar+ laser. Wavelength-dependent responses ranging from quadratic to pseudolinear were also recorded from the identical sample compn. when excited by Xe lamp/monochromator output in a conventional fluorometer, where the absorbance at λex dictates the obsd. incident power dependence. Finally, pure linear behavior was derived from noncoherent excitation for the 1st time at higher sensitizer concns.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XlsVCgtQ%253D%253D&md5=d417e89e432352f4a0fb23b1f72911d8
  37. 37
    Lakowicz, J. R. Principles of Fluorescence Spectroscopy, 3rd ed.; Springer Science: New York, 2006.
    Google Scholar
    There is no corresponding record for this reference.
  38. 38
    Mårtensson, J. Calculation of the Förster orientation factor for donor-acceptor systems with one chromophore of threefold or higher symmetry: zinc porphyrin Chem. Phys. Lett. 1994, 229, 449– 456 DOI: 10.1016/0009-2614(94)01065-X
    Google Scholar
    38
    Calculation of the Foerster orientation factor for donor-acceptor systems with one chromophore of threefold or higher symmetry: zinc porphyrin
    Martensson, Jerker
    Chemical Physics Letters (1994), 229 (4-5), 449-56CODEN: CHPLBC; ISSN:0009-2614. (Elsevier)
    Three different methods of calcn. of the Foerster orientation factor, κ2, for donor-acceptor systems in which one of the two chromophores have threefold or higher symmetry are discussed. Jablonski's sym. planar oscillator, as well as two perpendicular linear oscillators have been used as models for the transition dipole moment in the highly sym. chromophore. The methods of calcn. are applied to zinc porphyrin-free base porphyrin donor-acceptor systems. The best agreement between exptl. energy transfer rates or efficiencies and those calcd. according to Foerster theory is achieved when κ, not κ2, is calcd. as an av. and then squared. The av. is taken either of an infinite no. of κ-values or of two κ-values, depending on the oscillator model used for the transition dipole moment in the zinc porphyrin.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2MXhslOisbg%253D&md5=83787cbbab4766ef143f03e6be66581e
  39. 39
    Wu, G.-Z.; Gan, W.-X.; Leung, H.-K. Photophysical properties of meso-substituted octaethylporphines and their zinc complexes J. Chem. Soc., Faraday Trans. 1991, 87, 2933 DOI: 10.1039/ft9918702933
    Google Scholar
    39
    Porphyrin chemistry. 6. Photophysical properties of meso-substituted octaethylporphines and their zinc complexes
    Wu, Guozhang; Gan, Weixing; Leung, Hiukwong
    Journal of the Chemical Society, Faraday Transactions (1991), 87 (18), 2933-7CODEN: JCFTEV; ISSN:0956-5000.
    The absorption and emission spectral properties of a series of meso-substituted octaethylporphines and their Zn complexes were investigated. Changes in electronic absorption spectra induced by the substituents can be explained by M. Gouterman's (1978) 4-orbital model. In order to account fully for the effect of the meso-substituent on the photophys. properties, the steric factor of the meso-substituent has to be taken into consideration.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3MXms1Gktr8%253D&md5=85f60d34307c2f56323dcff5ee83697d
  40. 40
    Eaton, S. S.; Eaton, G. R.; Holm, R. H. Inter- and Intramolecular Ligand Exchange Reactions of Ruthenium(II) Carbonyl Porphine Complexes with Nitrogen Bases J. Organomet. Chem. 1972, 39, 179– 195 DOI: 10.1016/S0022-328X(00)88918-4
    Google Scholar
    40
    Inter- and intramolecular ligand exchange reactions of ruthenium(II) carbonyl porphine complexes with nitrogen bases
    Eaton, S. S.; Eaton, G. R.; Holm, R. H.
    Journal of Organometallic Chemistry (1972), 39 (1), 179-95CODEN: JORCAI; ISSN:0022-328X.
    To investigate both inter-and intramol. site exchange in coordinated nitrogenous bases the complexes of tetra-cis(p-isopropylphenyl)-porphinatoruthenium carbonyl with 4-tert-butylpyridine, 2-methylpyridine, 3,5-dimethylpyrazole, 4,5-dimethylpyridazine, and 3,6-dimethylpyridazine were studied by total line shape anal. of the variable temp. PMR spectra. Both types of exchange mechanisms were found in these complexes. All of the complexes undergo intermol. ligand exchange at rates ranging from ∼0.09 sec-1 ( G⧺ ∼19 kcal/mol) to 2 × 104 sec-1 ( G ⧺ ∼12 kcal/mol) at 25° for the various complexes, independent of the concn. of excess ligand. Thus the rate detg. step is dissocn. The two pyridazine complexes provide the first examples of intramol. ligand exchange with coordinated nitrogenous bases. The rates at 25° for intramol. site exchange (∼106 and 66 sec-1) are 20-85 times faster than the rates for intermol. ligand exchange in the same complexes. Within exptl. uncertainty there is no intramol. ligand site exchange in the 3,5-dimethylpyrazole complex. Full kinetic and mechanistic details are discussed.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE38Xks1Wjsrs%253D&md5=5dd5318cf8233b06a350ea0f16f1f5a2
  41. 41
    Da Ros, T.; Prato, M.; Guldi, D. M.; Ruzzi, M.; Pasimeni, L. Efficient charge separation in porphyrin-fullerene-ligand complexes Chem. - Eur. J. 2001, 7, 816– 827 DOI: 10.1002/1521-3765(20010216)7:4<816::AID-CHEM816>3.0.CO;2-A
    Google Scholar
    41
    Efficient charge separation in porphyrin-fullerene-ligand complexes
    Da Ros, Tatiana; Prato, Maurizio; Guldi, Dirk M.; Ruzzi, Marco; Pasimeni, Luigi
    Chemistry - A European Journal (2001), 7 (4), 816-827CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH)
    Photoprocesses assocd. with the complexation of a pyridine-functionalized C60 fullerene deriv. to ruthenium- and zinc-tetraphenylporphyrins (tpp) have been studied by time-resolved optical and transient EPR spectroscopies. It has been found that upon irradn. in toluene, a highly efficient triplet-triplet energy transfer governs the deactivation of the photoexcited [Ru(tpp)] while electron transfer (ET) from the porphyrin to the fullerene prevails in polar solvents. Complexation of [Zn(tpp)] by the fullerene deriv. is reversible and, following excitation of the [Zn(tpp)], gives rise to very efficient charge sepn. In fluid polar solvents such as THF and benzonitrile, radical-ion pairs (RPs) are generated both by intramol. ET inside the complex and by intermol. ET in the uncomplexed form. Charge-sepd. states have lifetimes of about 10 μs in THF and several hundred of microseconds in benzonitrile at room temp.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXhsFWjtLc%253D&md5=fbc31a39f10d6544accef06e5199f427
  42. 42
    Duan, P.; Yanai, N.; Kimizuka, N. Photon upconverting liquids: Matrix-free molecular upconversion systems functioning in air J. Am. Chem. Soc. 2013, 135, 19056– 19059 DOI: 10.1021/ja411316s
    Google Scholar
    42
    Photon Upconverting Liquids: Matrix-Free Molecular Upconversion Systems Functioning in Air
    Duan, Pengfei; Yanai, Nobuhiro; Kimizuka, Nobuo
    Journal of the American Chemical Society (2013), 135 (51), 19056-19059CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    A nonvolatile, in-air functioning liq. photon upconverting system is developed. A rationally designed triplet sensitizer (branched alkyl chain-modified Pt-(II) porphyrin) is homogeneously doped in energy-harvesting liq. acceptors with a 9,10-diphenylanthracene unit. A significantly high upconversion quantum yield of ∼28% is achieved in the solvent-free liq. state, even under aerated conditions. The liq. upconversion system shows a sequence of efficient triplet energy transfer and migration of two itinerant excited states which eventually collide with each other to produce a singlet excited state of the acceptor. The obsd. insusceptibility of upconversion luminescence to O indicates the sealing ability of molten alkyl chains introduced to liquefy chromophores. The involvement of the energy migration process in triplet-triplet annihilation (TTA) provides a new perspective in designing advanced photon upconversion systems.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhvFegsLbM&md5=908d0aa61c54b0ba1b87619de65d0a84
  43. 43
    Tilley, A. J.; Robotham, B. E.; Steer, R. P.; Ghiggino, K. P. Sensitized non-coherent photon upconversion by intramolecular triplettriplet annihilation in a diphenylanthracene pendant polymer Chem. Phys. Lett. 2015, 618, 198– 202 DOI: 10.1016/j.cplett.2014.11.016
    Google Scholar
    There is no corresponding record for this reference.
  44. 44
    Hisamitsu, S.; Yanai, N.; Kimizuka, N. Photon-Upconverting Ionic Liquids: Effective Triplet Energy Migration in Contiguous Ionic Chromophore Arrays Angew. Chem., Int. Ed. 2015, 54, 11550– 11554 DOI: 10.1002/anie.201505168
    Google Scholar
    44
    Photon-upconverting ionic liquids: Effective triplet energy migration in contiguous ionic chromophore arrays
    Hisamitsu, Shota; Yanai, Nobuhiro; Kimizuka, Nobuo
    Angewandte Chemie, International Edition (2015), 54 (39), 11550-11554CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
    Inspired by the bicontinuous ionic-network structure of ionic liqs. (ILs), we developed a new family of photofunctional ILs which show efficient triplet energy migration among contiguously arrayed ionic chromophores. A novel fluorescent IL, comprising an arom. 9,10-diphenylanthracene 2-sulfonate anion and an alkylated phosphonium cation, showed pronounced interactions between chromophores, as revealed by its spectral properties. Upon dissolving a triplet sensitizer, the IL demonstrated photon upconversion based on triplet-triplet annihilation (TTA-UC). Interestingly, the TTA-UC process in the chromophoric IL was optimized at a much lower excitation intensity compared to the previous nonionic liq. TTA-UC system. The superior TTA-UC in this IL system is characterized by a relatively high triplet diffusion const. (1.63×10-6 cm2 s-1) which is ascribed to the presence of ionic chromophore networks in the IL.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlOhurbE&md5=7504edbeb572476002d8084c3fc7c207
  45. 45
    Duan, P.; Yanai, N.; Nagatomi, H.; Kimizuka, N. Photon Upconversion in Supramolecular Gel Matrixes: Spontaneous Accumulation of Light-Harvesting DonorAcceptor Arrays in Nanofibers and Acquired Air Stability J. Am. Chem. Soc. 2015, 137, 1887– 1894 DOI: 10.1021/ja511061h
    Google Scholar
    There is no corresponding record for this reference.
  46. 46
    Ogawa, T.; Yanai, N.; Monguzzi, A.; Kimizuka, N. Highly Efficient Photon Upconversion in Self-Assembled Light-Harvesting Molecular Systems Sci. Rep. 2015, 5, 10882 DOI: 10.1038/srep10882
    Google Scholar
    46
    Highly Efficient Photon Upconversion in Self-Assembled Light-Harvesting Molecular Systems
    Ogawa, Taku; Yanai, Nobuhiro; Monguzzi, Angelo; Kimizuka, Nobuo
    Scientific Reports (2015), 5 (), 10882CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)
    To meet the world's demands on the development of sunlight-powered renewable energy prodn., triplet-triplet annihilation-based photon upconversion (TTA-UC) has raised great expectations. However, an ideal highly efficient, low-power, and in-air TTA-UC has not been achieved. Here, we report a novel self-assembly approach to achieve this, which enabled highly efficient TTA-UC even in the presence of oxygen. A newly developed lipophilic 9,10-diphenylanthracene-based emitter mol. functionalized with multiple hydrogen-bonding moieties spontaneously coassembled with a triplet sensitizer in org. media, showing efficient triplet sensitization and subsequent triplet energy migration among the preorganized chromophores. This supramol. light-harvesting system shows a high UC quantum yield of 30% optimized at low excitation power in deaerated conditions. Significantly, the UC emission largely remains even in an air-satd. soln., and this approach is facilely applicable to organogel and solid-film systems.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFyiu7vI&md5=a8c179296f3a11091f96c640812186ba

Cited By

Click to copy section linkSection link copied!

This article is cited by 55 publications.

  1. Hui Fang, Michael J. Wilhelm, Danielle L. Kuhn, Zachary Zander, Hai-Lung Dai. Relaxation of Photoexcited Electrons through Transition Dipole Coupling in the Hybrid Nanocomposite Porphyrin/Ag/TiO2. The Journal of Physical Chemistry C 2024, 128 (42) , 17953-17960. https://doi.org/10.1021/acs.jpcc.4c03784
  2. Jishnudas Chakkamalayath, Prashant V. Kamat. Demystifying Triplet–Triplet Annihilation Mechanism in the CsPbI3–Rubrene–DBP Upconversion System. Journal of the American Chemical Society 2024, 146 (26) , 18095-18103. https://doi.org/10.1021/jacs.4c05178
  3. Naifang Liu, Hailong Chen, Jie Su, Yuxiang Weng, Jagadese J. Vittal, Sheng-Li Huang, Jianzhuang Jiang. Porphyrin–Sensitizers and Anthracene–Annihilators Built in Isostructural Frameworks for Investigating Triplet–Triplet Annihilation Upconversion. Inorganic Chemistry 2024, 63 (10) , 4691-4696. https://doi.org/10.1021/acs.inorgchem.3c04313
  4. Henrik Gotfredsen, Dominik Thiel, Phillip M. Greißel, Lan Chen, Marcel Krug, Ilias Papadopoulos, Michael J. Ferguson, Mogens Brøndsted Nielsen, Tomás Torres, Timothy Clark, Dirk M. Guldi, Rik R. Tykwinski. Sensitized Singlet Fission in Rigidly Linked Axial and Peripheral Pentacene-Subphthalocyanine Conjugates. Journal of the American Chemical Society 2023, 145 (17) , 9548-9563. https://doi.org/10.1021/jacs.2c13353
  5. Keshav Kumar Jha, Amrutha Prabhakaran, Christopher S. Burke, Marcus Schulze, Ulrich S. Schubert, Tia E. Keyes, Michael Jäger, Benjamin Dietzek Ivanšić. Triplet–Triplet Annihilation Upconversion by Polymeric Sensitizers. The Journal of Physical Chemistry C 2022, 126 (8) , 4057-4066. https://doi.org/10.1021/acs.jpcc.1c09897
  6. Fredrik Edhborg, Hakan Bildirir, Pankaj Bharmoria, Kasper Moth-Poulsen, Bo Albinsson. Intramolecular Triplet–Triplet Annihilation Photon Upconversion in Diffusionally Restricted Anthracene Polymer. The Journal of Physical Chemistry B 2021, 125 (23) , 6255-6263. https://doi.org/10.1021/acs.jpcb.1c02856
  7. Axel Olesund, Victor Gray, Jerker Mårtensson, Bo Albinsson. Diphenylanthracene Dimers for Triplet–Triplet Annihilation Photon Upconversion: Mechanistic Insights for Intramolecular Pathways and the Importance of Molecular Geometry. Journal of the American Chemical Society 2021, 143 (15) , 5745-5754. https://doi.org/10.1021/jacs.1c00331
  8. Indranil Roy, Subhadip Goswami, Ryan M. Young, Itai Schlesinger, Mohammad Rasel Mian, Alan E. Enciso, Xuan Zhang, Jessica E. Hornick, Omar K. Farha, Michael R. Wasielewski, Joseph T. Hupp, J. Fraser Stoddart. Photon Upconversion in a Glowing Metal–Organic Framework. Journal of the American Chemical Society 2021, 143 (13) , 5053-5059. https://doi.org/10.1021/jacs.1c00298
  9. Xiu Wang, Wei Yuan, Ming Xu, Fuyou Li. Two-Photon Excitation-Based Imaging Postprocessing Algorithm Model for Background-Free Bioimaging. Analytical Chemistry 2021, 93 (4) , 2551-2559. https://doi.org/10.1021/acs.analchem.0c04611
  10. Ashley Arcidiacono, Yan Zhou, Wendi Zhang, Jeffrey O. Ellison, Suliman Ayad, Erica S. Knorr, Autumn N. Peters, Lianqing Zheng, Wei Yang, S. Scott Saavedra, Kenneth Hanson. Examining the Influence of Bilayer Structure on Energy Transfer and Molecular Photon Upconversion in Metal Ion Linked Multilayers. The Journal of Physical Chemistry C 2020, 124 (43) , 23597-23610. https://doi.org/10.1021/acs.jpcc.0c08715
  11. Indranil Roy, Amine Garci, Yassine Beldjoudi, Ryan M. Young, David J. Pe, Minh T. Nguyen, Partha Jyoti Das, Michael R. Wasielewski, J. Fraser Stoddart. Host–Guest Complexation-Mediated Supramolecular Photon Upconversion. Journal of the American Chemical Society 2020, 142 (39) , 16600-16609. https://doi.org/10.1021/jacs.0c05445
  12. Fredrik Edhborg, Betül Küçüköz, Victor Gray, Bo Albinsson. Singlet Energy Transfer in Anthracene–Porphyrin Complexes: Mechanism, Geometry, and Implications for Intramolecular Photon Upconversion. The Journal of Physical Chemistry B 2019, 123 (46) , 9934-9943. https://doi.org/10.1021/acs.jpcb.9b07991
  13. Chen Ye, Victor Gray, Jerker Mårtensson, Karl Börjesson. Annihilation Versus Excimer Formation by the Triplet Pair in Triplet–Triplet Annihilation Photon Upconversion. Journal of the American Chemical Society 2019, 141 (24) , 9578-9584. https://doi.org/10.1021/jacs.9b02302
  14. Serhii I. Vasylevskyi, Dario M. Bassani, Katharina M. Fromm. Anion-Induced Structural Diversity of Zn and Cd Coordination Polymers Based on Bis-9,10-(pyridine-4-yl)-anthracene, Their Luminescent Properties, and Highly Efficient Sensing of Nitro Derivatives and Herbicides. Inorganic Chemistry 2019, 58 (9) , 5646-5653. https://doi.org/10.1021/acs.inorgchem.8b03628
  15. Tristan Dilbeck, Kenneth Hanson. Molecular Photon Upconversion Solar Cells Using Multilayer Assemblies: Progress and Prospects. The Journal of Physical Chemistry Letters 2018, 9 (19) , 5810-5821. https://doi.org/10.1021/acs.jpclett.8b02635
  16. Qi Chen, Yiming Liu, Xinyan Guo, Jiang Peng, Sofia Garakyaraghi, Christopher M. Papa, Felix N. Castellano, Dahui Zhao, Yuguo Ma. Energy Transfer Dynamics in Triplet–Triplet Annihilation Upconversion Using a Bichromophoric Heavy-Atom-Free Sensitizer. The Journal of Physical Chemistry A 2018, 122 (33) , 6673-6682. https://doi.org/10.1021/acs.jpca.8b05901
  17. Syed S. Razi, Yun Hee Koo, Woojae Kim, Wenbo Yang, Zhijia Wang, Habtom Gobeze, Francis D’Souza, Jianzhang Zhao, Dongho Kim. Ping-Pong Energy Transfer in a Boron Dipyrromethane Containing Pt(II)–Schiff Base Complex: Synthesis, Photophysical Studies, and Anti-Stokes Shift Increase in Triplet–Triplet Annihilation Upconversion. Inorganic Chemistry 2018, 57 (9) , 4877-4890. https://doi.org/10.1021/acs.inorgchem.7b02989
  18. Svante Hedström, Subhajyoti Chaudhuri, Nathan T. La Porte, Benjamin Rudshteyn, Jose F. Martinez, Michael R. Wasielewski, and Victor S. Batista . Thousandfold Enhancement of Photoreduction Lifetime in Re(bpy)(CO)3 via Spin-Dependent Electron Transfer from a Perylenediimide Radical Anion Donor. Journal of the American Chemical Society 2017, 139 (46) , 16466-16469. https://doi.org/10.1021/jacs.7b09438
  19. Kejing Xu, Jianzhang Zhao, and Evan G. Moore . Covalently Bonded Perylene–DiiodoBodipy Dyads for Thiol-Activatable Triplet–Triplet Annihilation Upconversion. The Journal of Physical Chemistry C 2017, 121 (41) , 22665-22679. https://doi.org/10.1021/acs.jpcc.7b06922
  20. Tristan Dilbeck, Jamie C. Wang, Yan Zhou, Andrew Olsson, Milan Sykora, and Kenneth Hanson . Elucidating the Energy- and Electron-Transfer Dynamics of Photon Upconversion in Self-Assembled Bilayers. The Journal of Physical Chemistry C 2017, 121 (36) , 19690-19698. https://doi.org/10.1021/acs.jpcc.7b07003
  21. Carlito S. Ponseca, Jr., Pavel Chábera, Jens Uhlig, Petter Persson, and Villy Sundström . Ultrafast Electron Dynamics in Solar Energy Conversion. Chemical Reviews 2017, 117 (16) , 10940-11024. https://doi.org/10.1021/acs.chemrev.6b00807
  22. Zhijia Wang, Jianzhang Zhao, Antonio Barbon, Antonio Toffoletti, Yan Liu, Yonglin An, Liang Xu, Ahmet Karatay, Halime Gul Yaglioglu, Elif Akhüseyin Yildiz, and Mustafa Hayvali . Radical-Enhanced Intersystem Crossing in New Bodipy Derivatives and Application for Efficient Triplet–Triplet Annihilation Upconversion. Journal of the American Chemical Society 2017, 139 (23) , 7831-7842. https://doi.org/10.1021/jacs.7b02063
  23. Prashanth Venkatesan, Preeti Pal, Siew Suan Ng, Jui-Yen Lin, Ruey-An Doong. Sensitized triplet-triplet annihilation-based photon upconversion: Assembly strategy and key consideration for sustainable energy and biomedical applications. Coordination Chemistry Reviews 2025, 523 , 216266. https://doi.org/10.1016/j.ccr.2024.216266
  24. Jan Riebe, Benedikt Bädorf, Sarah Löffelsender, Matias E. Gutierrez Suburu, María Belén Rivas Aiello, Cristian A. Strassert, Stefan Grimme, Jochen Niemeyer. Molecular folding governs switchable singlet oxygen photoproduction in porphyrin-decorated bistable rotaxanes. Communications Chemistry 2024, 7 (1) https://doi.org/10.1038/s42004-024-01247-7
  25. Ashley Arcidiacono, Cory Ruchlin, Grace M. McLeod, Dhruba Pattadar, Sarah Lindbom, Alex J. Robb, Suliman Ayad, Nikolas R. Dos Santos, Igor V. Alabugin, S. Scott Saavedra, Kenneth Hanson. Structural insights to metal ion linked multilayers on metal oxide surfaces via energy transfer and polarized ATR measurements. Journal of Materials Chemistry A 2024, 12 (42) , 28882-28891. https://doi.org/10.1039/D4TA05156D
  26. Kai‐Hong Hsieh, Yuan‐Zhen Zhuang, Jing‐Xiang Huang, Zheng‐Yu Wei, Yong‐Yun Zhang, Jiun‐Haw Lee, Tien‐Lung Chiu, Man‐kit Leung. Enhancing Triplet–Triplet Annihilation Upconversion Performance Through Anthracene–Carbazole Interactions for Organic Optoelectronic Applications. Advanced Photonics Research 2024, 5 (10) https://doi.org/10.1002/adpr.202300344
  27. Ekaterina N. Ovchenkova, Nataliya G. Bichan, Arshak A. Tsaturyan, Tatyana N. Lomova. Non-covalent self-assembly of substituted phthalocyanine with C60, C70, and 9-phenylanthracene: spectroscopic insights and DFT calculations. Tetrahedron 2024, 3 , 134106. https://doi.org/10.1016/j.tet.2024.134106
  28. V. Vinoth Kumar, P. Gayathri, R. Sankar, C. Arunamaheswari, R. Prasath. Investigation on the Role of Molecular Planarity and Conjugation Effects on Physicochemical Properties of Anthracene and Pyrene Appended meso -5,15-Bis(Thien-2-yl)-10,20-Diphenylporphyrin Triads. Polycyclic Aromatic Compounds 2023, 43 (9) , 8319-8332. https://doi.org/10.1080/10406638.2022.2149566
  29. Andrew J. Carrod, Victor Gray, Karl Börjesson. Recent advances in triplet–triplet annihilation upconversion and singlet fission, towards solar energy applications. Energy & Environmental Science 2022, 15 (12) , 4982-5016. https://doi.org/10.1039/D2EE01600A
  30. Alessandra Ronchi, Angelo Monguzzi. Sensitized triplet–triplet annihilation based photon upconversion in full organic and hybrid multicomponent systems. Chemical Physics Reviews 2022, 3 (4) https://doi.org/10.1063/5.0112032
  31. Ruomeng Wan, Dong-Gwang Ha, Jin-Hu Dou, Woo Seok Lee, Tianyang Chen, Julius J. Oppenheim, Jian Li, William A. Tisdale, Mircea Dincă. Dipole-mediated exciton management strategy enabled by reticular chemistry. Chemical Science 2022, 13 (36) , 10792-10797. https://doi.org/10.1039/D2SC01127A
  32. Yanpeng Liu, Tianjun Yu, Yi Zeng, Jinping Chen, Guoqiang Yang, Yi Li. Coupling Red‐to‐blue Upconversion Organic Microcrystals with Cd 0.5 Zn 0.5 S for Efficient and Durable Photocatalytic Hydrogen Production. Chemistry – An Asian Journal 2022, 17 (13) https://doi.org/10.1002/asia.202200343
  33. Lamia Saidi, Amira Samet, Thameur Dammak, Sebastien Pillet, Younes Abid. Down and up conversion luminescence of the lead-free organic metal halide material: (C 9 H 8 NO) 2 SnCl 6 ·2H 2 O. Physical Chemistry Chemical Physics 2021, 23 (29) , 15574-15581. https://doi.org/10.1039/D1CP01702K
  34. Mo Yang, Sara Sheykhi, Yu Zhang, Carsten Milsmann, Felix N. Castellano. Low power threshold photochemical upconversion using a zirconium( iv ) LMCT photosensitizer. Chemical Science 2021, 12 (26) , 9069-9077. https://doi.org/10.1039/D1SC01662H
  35. Waqas Ahmad, Jingjing Wang, Huanhuan Li, Qin Ouyang, Wanhua Wu, Quansheng Chen. Strategies for combining triplet–triplet annihilation upconversion sensitizers and acceptors in a host matrix. Coordination Chemistry Reviews 2021, 439 , 213944. https://doi.org/10.1016/j.ccr.2021.213944
  36. Helen Tunstall-Garcia, Bethan L. Charles, Rachel C. Evans. The Role of Polyhedral Oligomeric Silsesquioxanes in Optical Applications. Advanced Photonics Research 2021, 2 (6) https://doi.org/10.1002/adpr.202000196
  37. Aurore Caron, Guillaume Noirbent, Didier Gigmes, Frédéric Dumur, Jacques Lalevée. Near‐Infrared PhotoInitiating Systems: Photothermal versus Triplet–Triplet Annihilation‐Based Upconversion Polymerization. Macromolecular Rapid Communications 2021, 42 (11) https://doi.org/10.1002/marc.202100047
  38. Biswajit Manna, Amitabha Nandi. The triplet exciton dynamics and diffusion properties of zinc and platinum-octaethylporphyrin nanoaggregates. Journal of Photochemistry and Photobiology A: Chemistry 2021, 408 , 113105. https://doi.org/10.1016/j.jphotochem.2020.113105
  39. Kirill P. Birin, Inna A. Abdulaeva, Daria A. Polivanovskaia, Alexander G. Martynov, Alexander V. Shokurov, Yulia G. Gorbunova, Aslan Yu Tsivadze. Imidazoporphyrins with appended polycyclic aromatic hydrocarbons: To conjugate or not to conjugate?. Dyes and Pigments 2021, 186 , 109042. https://doi.org/10.1016/j.dyepig.2020.109042
  40. Chen Ye, Bo Albinsson, Karl Börjesson. Kinetics and Efficiency of Triplet‐Triplet Annihilation Photon Upconversion under Pulsed Excitation Conditions. Chemistry–Methods 2021, 1 (1) , 17-21. https://doi.org/10.1002/cmtd.202000046
  41. Seokwoo Kang, Jin-Suk Huh, Jang-Joo Kim, Jongwook Park. Highly efficient deep-blue fluorescence OLEDs with excellent charge balance based on phenanthro[9,10- d ]oxazole-anthracene derivatives. Journal of Materials Chemistry C 2020, 8 (32) , 11168-11176. https://doi.org/10.1039/D0TC01811B
  42. Maria Sittig, Benny Schmidt, Helmar Görls, Thomas Bocklitz, Maria Wächtler, Stefan Zechel, Martin D. Hager, Benjamin Dietzek. Fluorescence upconversion by triplet–triplet annihilation in all-organic poly(methacrylate)-terpolymers. Physical Chemistry Chemical Physics 2020, 22 (7) , 4072-4079. https://doi.org/10.1039/D0CP00232A
  43. Kazuo Tanaka, Wataru Ohashi, Kenichi Inafuku, Shohei Shiotsu, Yoshiki Chujo. Development of the sensitizer for generating higher-energy photons under diluted condition via the triplet-triplet annihilation-supported upconversion. Dyes and Pigments 2020, 172 , 107821. https://doi.org/10.1016/j.dyepig.2019.107821
  44. David Jefferies, Timothy W. Schmidt, Laszlo Frazer. Photochemical Upconversion Theory: Importance of Triplet Energy Levels and Triplet Quenching. Physical Review Applied 2019, 12 (2) https://doi.org/10.1103/PhysRevApplied.12.024023
  45. Hossein Goudarzi, Saurav Limbu, Juan Cabanillas-González, Vassiliki M. Zenonos, Ji-Seon Kim, Panagiotis E. Keivanidis. Impact of molecular conformation on triplet-fusion induced photon energy up-conversion in the absence of exothermic triplet energy transfer. Journal of Materials Chemistry C 2019, 7 (12) , 3634-3643. https://doi.org/10.1039/C8TC06283H
  46. Victor Gray, Kasper Moth-Poulsen, Bo Albinsson, Maria Abrahamsson. Towards efficient solid-state triplet–triplet annihilation based photon upconversion: Supramolecular, macromolecular and self-assembled systems. Coordination Chemistry Reviews 2018, 362 , 54-71. https://doi.org/10.1016/j.ccr.2018.02.011
  47. Toshiko Mizokuro, Aizitiaili Abulikemu, Yusuke Sakagami, Tetsuro Jin, Kenji Kamada. Enhanced phosphorescence properties of a Pt-porphyrin derivative fixed on the surface of nano-porous glass. Photochemical & Photobiological Sciences 2018, 17 (5) , 622-627. https://doi.org/10.1039/c7pp00449d
  48. Abagail K. Williams, Brad J. Davis, Erin R. Crater, Joseph R. Lott, Yoan C. Simon, Jason D. Azoulay. Thiol–ene click chemistry: a modular approach to solid-state triplet–triplet annihilation upconversion. Journal of Materials Chemistry C 2018, 6 (15) , 3876-3881. https://doi.org/10.1039/C7TC05729F
  49. Victor Gray, Betül Küçüköz, Fredrik Edhborg, Maria Abrahamsson, Kasper Moth-Poulsen, Bo Albinsson. Singlet and triplet energy transfer dynamics in self-assembled axial porphyrin–anthracene complexes: towards supra-molecular structures for photon upconversion. Physical Chemistry Chemical Physics 2018, 20 (11) , 7549-7558. https://doi.org/10.1039/C8CP00884A
  50. Yan Zhou, Suliman Ayad, Cory Ruchlin, Victoria Posey, Sean P. Hill, Qiang Wu, Kenneth Hanson. Examining the role of acceptor molecule structure in self-assembled bilayers: surface loading, stability, energy transfer, and upconverted emission. Physical Chemistry Chemical Physics 2018, 20 (31) , 20513-20524. https://doi.org/10.1039/C8CP03628D
  51. Steponas Raišys, Saulius Juršėnas, Yoan C. Simon, Christoph Weder, Karolis Kazlauskas. Enhancement of triplet-sensitized upconversion in rigid polymers via singlet exciton sink approach. Chemical Science 2018, 9 (33) , 6796-6802. https://doi.org/10.1039/C8SC02151A
  52. Qiaohui Zhou, Miaomiao Zhou, Yaxiong Wei, Xiaoguo Zhou, Shilin Liu, Song Zhang, Bing Zhang. Solvent effects on the triplet–triplet annihilation upconversion of diiodo-Bodipy and perylene. Physical Chemistry Chemical Physics 2017, 19 (2) , 1516-1525. https://doi.org/10.1039/C6CP06897A
  53. Victor Gray, Ambra Dreos, Paul Erhart, Bo Albinsson, Kasper Moth-Poulsen, Maria Abrahamsson. Loss channels in triplet–triplet annihilation photon upconversion: importance of annihilator singlet and triplet surface shapes. Physical Chemistry Chemical Physics 2017, 19 (17) , 10931-10939. https://doi.org/10.1039/C7CP01368J
  54. Sundaram Chandrasekaran, Yen-Linh Thi Ngo, Lijun Sui, Eui Jung Kim, Dinh Khoi Dang, Jin Suk Chung, Seung Hyun Hur. Highly enhanced visible light water splitting of CdS by green to blue upconversion. Dalton Trans. 2017, 46 (40) , 13912-13919. https://doi.org/10.1039/C7DT02936E
  55. Laura A. Büldt, Oliver S. Wenger. Chromium complexes for luminescence, solar cells, photoredox catalysis, upconversion, and phototriggered NO release. Chem. Sci. 2017, 8 (11) , 7359-7367. https://doi.org/10.1039/C7SC03372A
Download PDF
Go to The Journal of Physical Chemistry C
Get e-Alerts
Get e-Alerts

The Journal of Physical Chemistry C

Cite this: J. Phys. Chem. C 2016, 120, 34, 19018–19026
Click to copy citationCitation copied!
https://doi.org/10.1021/acs.jpcc.6b06298
Published August 9, 2016

Copyright © 2016 American Chemical Society. This publication is licensed under these Terms of Use.

Request reuse permissions

Article Views

5458

Altmetric

-

Citations

55
Learn about these metrics

Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.

Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.

The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated.

  • Abstract

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 1

    Figure 1. Jablonski diagram explaining the triplet–triplet annihilation upconversion process. A sensitizer first absorbs a low energy photon and rapidly populates its first triplet excited state after ISC from the singlet state. The triplet energy is then transferred to an annihilator species through TET, generating one triplet excited annihilator molecule. When two triplet excited annihilator molecules come together they can undergo TTA to form a singlet excited annihilator which can deactivate to its ground state by emitting a photon. If the sensitizer and annihilator are in close proximity, e.g., when connected, a new deactivation pathway is possible, namely singlet energy transfer of the excited singlet annihilator, short-circuiting the system.

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 2

    Figure 2. Molar absorptivity (solid) and normalized fluorescence (dashed) of the studied annihilators DPA (black), Ph1AnPyr (orange), Ph2AnPyr (blue), Ph3AnPyr (green), and Ph5AnPyr (red) and the sensitizer ZnOEP (gray).

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 3

    Figure 3. (Left) Upconverted emission plotted against excitation power (532 nm). (Right) Upconversion quantum yield. Samples of 1 μM ZnOEP sensitizer and 2.5 mM DPA (black squares), 2.5 mM Ph1AnPyr (orange diamonds), 2.5 mM Ph2AnPyr (blue circles), 0.23 mM Ph3AnPyr (green triangles), and 2.5 mM Ph5AnPyr (red open circles).

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 4

    Figure 4. Upper: Fluorescence decay for Ph5AnPyr (14 μM), alone (black) corresponding fit (green), with ZnOEP (140 μM) (blue), corresponding fit (red) and instrument response function (yellow). The bump at 2 ns for Ph5AnPyr alone (black), is due to the instrument response. Lower: Residual to the fitted decays,Ph5AnPyr, alone (black) and with ZnOEP (blue).

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 5

    Figure 5. (a) Angles between donor (blue) and acceptor (black) transition dipole moments used for calculating the orientation factor, κ2, for a donor–acceptor pair. (b) Transition dipole moment in anthracene derivatives (blue) and the degenerate transition dipole moments in ZnOEP are represented by two perpendicular transitions (green and black) spanning the porphyrin plane (orange). The y,z-plane is colored gray for clarity. Also illustrated are the angles relevant for the black transition dipole moment component in ZnOEP, β and γ. (c) As in b, now illustrating the angles relevant for the perpendicular dipole moment component (green arrow), β⊥ and γ⊥.

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 6

    Figure 6. Calculated triplet energy transfer efficiency for diffusion-controlled energy transfer with a sensitizer lifetime of 200 μs (blue dashed) and 2 μs (blue dotted). The fraction of bound sensitizer calculated for KB = 6000 M–1 and sensitizer concentrations between 1 μM and 1 mM (black) as well as the fraction of bound sensitizer calculated for KB = 60000 M–1 and a sensitizer concentration of 1 μM (red).

    High Resolution Image
    Download MS PowerPoint Slide

  • References

    This article references 46 other publications.

    1. 1
      Kurreck, H.; Huber, M. Model reactions for photosynthesis-photoinduced charge and energy transfer between covalently linked porphyrin and quinone units Angew. Chem., Int. Ed. Engl. 1995, 34, 849– 866 DOI: 10.1002/anie.199508491
      There is no corresponding record for this reference.
    2. 2
      Andréasson, J.; Zetterqvist, H.; Kajanus, J.; Mårtensson, J.; Albinsson, B. Efficient non-radiative deactivation and conformational flexibility of meso-diaryloctaalkylporphyrins in the excited triplet state J. Phys. Chem. A 2000, 104, 9307– 9314 DOI: 10.1021/jp0015574
      There is no corresponding record for this reference.
    3. 3
      Islangulov, R. R.; Kozlov, D. V.; Castellano, F. N. Low power upconversion using MLCT sensitizers Chem. Commun. 2005, 1, 3776– 3778 DOI: 10.1039/b506575e
      There is no corresponding record for this reference.
    4. 4
      Baluschev, S.; Miteva, T.; Yakutkin, V.; Nelles, G.; Yasuda, a.; Wegner, G. Up-conversion fluorescence: Noncoherent excitation by sunlight Phys. Rev. Lett. 2006, 97, 7– 9 DOI: 10.1103/PhysRevLett.97.143903
      There is no corresponding record for this reference.
    5. 5
      Baluschev, S.; Yakutkin, V.; Wegner, G.; Miteva, T.; Nelles, G.; Yasuda, A.; Chernov, S.; Aleshchenkov, S.; Cheprakov, A. Upconversion with ultrabroad excitation band: Simultaneous use of two sensitizers Appl. Phys. Lett. 2007, 90, 181103 DOI: 10.1063/1.2734475
      5
      Upconversion with ultrabroad excitation band: Simultaneous use of two sensitizers
      Baluschev, S.; Yakutkin, V.; Wegner, G.; Miteva, T.; Nelles, G.; Yasuda, A.; Chernov, S.; Aleshchenkov, S.; Cheprakov, A.
      Applied Physics Letters (2007), 90 (18), 181103/1-181103/3CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)
      The authors demonstrate the ability to combine sensitizers effectively working with single emitter to increase the excitation window for noncoherent upconversion. They show effective upconversion of the red part of the sun spectrum realized by ultralow excitation intensity (≥1 W cm-2) and ultrabroad excitation spectrum (Δλ ∼80 nm).
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXlsVKrtbs%253D&md5=5d23e4aa617e9a2cb4a6247ed517e28e
    6. 6
      Islangulov, R. R.; Lott, J.; Weder, C.; Castellano, F. N. Low-power upconversion in solid polymer films J. Am. Chem. Soc. 2007, 129, 12652– 12653 DOI: 10.1021/ja075014k
      There is no corresponding record for this reference.
    7. 7
      Baluschev, S.; Yakutkin, V.; Miteva, T.; Wegner, G.; Roberts, T.; Nelles, G.; Yasuda, A.; Chernov, S.; Aleshchenkov, S.; Cheprakov, A. A general approach for non-coherently excited annihilation up-conversion: Transforming the solar-spectrum New J. Phys. 2008, 10, 013007 DOI: 10.1088/1367-2630/10/1/013007
      There is no corresponding record for this reference.
    8. 8
      Singh-Rachford, T. N.; Castellano, F. N. Low Power Visible-to-UV Upconversion J. Phys. Chem. A 2009, 113, 5912– 5917 DOI: 10.1021/jp9021163
      8
      Low Power Visible-to-UV Upconversion
      Singh-Rachford, Tanya N.; Castellano, Felix N.
      Journal of Physical Chemistry A (2009), 113 (20), 5912-5917CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      Low power visible-to-UV photon upconversion is demonstrated for the 1st time, achieved from 2 simple org. chromophores dissolved in benzene. Selective 442 nm excitation of the triplet sensitizer 2,3-butanedione (biacetyl) in the presence of the laser dye 2,5-diphenyloxazole (PPO) results in the observation of singlet fluorescence from the latter in the UV centered at 360 nm, anti-Stokes shifted by a record 0.64 eV with respect to the excitation. All of the exptl. data are consistent with the upconverted singlet PPO fluorescence being produced as a result of biacetyl-sensitized triplet-triplet annihilation (TTA) of triplet excited PPO chromophores. Nanosecond laser flash photolysis performed under pseudo-first-order conditions revealed the bimol. rate const. of triplet-triplet energy transfer between the biacetyl sensitizer and PPO acceptor, kq = 9.0 × 108 M-1s-1. The TTA process was confirmed by the quadratic dependence of the upconverted integrated PPO emission intensity measured with respect to incident 442 nm light power d. The max. quantum yield of the upconverted emission (0.0058 ± 0.0002) was detd. relative to 1,8-diphenyl-1,3,5,7-octatetraene, both measured with 0.389 W/cm2 incident power d. The PPO triplet-triplet annihilation rate const. (kTT) was detd. from transient absorption decays monitored at the peak of its characteristic triplet-to-triplet excited-state absorption (500 nm) as a function of incident pulsed laser fluence; this process attains the diffusion limit in benzene at room temp., kTT = 1.1 ± 0.1 × 1010 M-1 s-1.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXltVCnt78%253D&md5=e767b7271fea77f93956e8404ed01ca2
    9. 9
      Ji, S.; Wu, W.; Wu, W.; Guo, H.; Zhao, J. Ruthenium(II) polyimine complexes with a long-lived 3IL excited state or a 3MLCT/3IL equilibrium: Efficient triplet sensitizers for low-power upconversion Angew. Chem., Int. Ed. 2011, 50, 1626– 1629 DOI: 10.1002/anie.201006192
      9
      Ruthenium(II) polyimine complexes with a long-lived 3IL excited state or a 3MLCT/3IL equilibrium: efficient triplet sensitizers for low-power upconversion
      Ji, Shaomin; Wu, Wanhua; Wu, Wenting; Guo, Huimin; Zhao, Jianzhang
      Angewandte Chemie, International Edition (2011), 50 (7), 1626-1629, S1626/1-S1626/7CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
      TTA (triplet-triplet annihilation)-based upconversion was achieved by using a Ru(II) complex with a long-lived 3IL (intraligand) excited state. The results indicated that the 3IL excited state is much more efficient in sensitizing the TTA-based upconversion than the 3MLCT excited states.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhslygs7w%253D&md5=52704f2dbf62333bb2624ddb235cc307
    10. 10
      Trupke, T.; Green, M. A.; Würfel, P. Improving solar cell efficiencies by up-conversion of sub-band-gap light J. Appl. Phys. 2002, 92, 4117– 4122 DOI: 10.1063/1.1505677
      10
      Improving solar cell efficiencies by up-conversion of sub-band-gap light
      Trupke, T.; Green, M. A.; Wurfel, P.
      Journal of Applied Physics (2002), 92 (7), 4117-4122CODEN: JAPIAU; ISSN:0021-8979. (American Institute of Physics)
      A system for solar energy conversion using the up-conversion of sub-band-gap photons to increase the max. efficiency of a single-junction conventional, bifacial solar cell is discussed. An up-converter is located behind a solar cell and absorbs transmitted sub-band-gap photons via sequential ground state absorption/excited state absorption processes in a three-level system. This generates an excited state in the up-converter from which photons are emitted which are subsequently absorbed in the solar cell and generate electron-hole pairs. The solar energy conversion efficiency of this system in the radiative limit is calcd. for different cell geometries and different illumination conditions using a detailed balance model. It is shown that in contrast to an impurity photovoltaic solar cell the conditions of photon selectivity and of complete absorption of high-energy photons can be met simultaneously in this system by restricting the widths of the bands in the up-converter. The upper limit of the energy conversion efficiency of the system is found to be 63.2% for concd. sunlight and 47.6% for nonconcd. sunlight.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XntF2msLc%253D&md5=0b7cc42919c3bec2316a39bb2a6fc9af
    11. 11
      Ekins-Daukes, N. J.; Schmidt, T. W. A molecular approach to the intermediate band solar cell: The symmetric case Appl. Phys. Lett. 2008, 93, 063507 DOI: 10.1063/1.2970157
      11
      A molecular approach to the intermediate band solar cell: The symmetric case
      Ekins-Daukes, N. J.; Schmidt, T. W.
      Applied Physics Letters (2008), 93 (6), 063507/1-063507/3CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)
      Mol. materials may overcome some of the difficulties for making an intermediate band solar cell by storing energy in long-lived triplet states. Both the problems of fast nonradiative interband relaxation and selective photon absorption can be solved by this approach. A practical implementation of the mol. intermediate band solar cell is considered with a sym. band alignment, resting on a proven triplet-triplet annihilation process. The limiting power conversion efficiency for this system exceeds that of a single bandgap device over a broad range, peaking at 40.6% for 1.9 eV under 1 sun illumination. (c) 2008 American Institute of Physics.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtVSjsb7O&md5=9acd4de681b78adeb94de447df8a84ab
    12. 12
      de Wild, J.; Meijerink, A.; Rath, J. K.; van Sark, W. G. J. H. M.; Schropp, R. E. I. Upconverter solar cells: materials and applications Energy Environ. Sci. 2011, 4, 4835 DOI: 10.1039/c1ee01659h
      12
      Upconverter solar cells: materials and applications
      de Wild, J.; Meijerink, A.; Rath, J. K.; van Sark, W. G. J. H. M.; Schropp, R. E. I.
      Energy & Environmental Science (2011), 4 (12), 4835-4848CODEN: EESNBY; ISSN:1754-5706. (Royal Society of Chemistry)
      A review. Spectral conversion of sunlight is a promising route to reduce spectral mismatch losses that are responsible for the major part of the efficiency losses in solar cells. Both upconversion and down conversion materials are presently explored. In an upconversion process, photons with an energy lower than the band gap of the solar cell are converted to higher energy photons. These higher photons are directed back to the solar cell and absorbed, thus increasing the efficiency. Different types of up converter materials are investigated, based on luminescent ions or org. mols. Proof of principle expts. with lanthanide ion based up converters have indicated that the benefit of an upconversion layer is limited by the high light intensities needed to reach high upconversion quantum efficiencies. To address this limitation, up converter materials may be combined with quantum dots or plasmonic particles to enhance the upconversion efficiency and improve the feasibility of applying up converters in com. solar cells.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFKlurbL&md5=b81db4a8a8c0494fd1e10c9a3be8e3eb
    13. 13
      Briggs, J. a.; Atre, A. C.; Dionne, J. a. Narrow-bandwidth solar upconversion: Case studies of existing systems and generalized fundamental limits J. Appl. Phys. 2013, 113, 124509 DOI: 10.1063/1.4796092
      13
      Narrow-bandwidth solar upconversion: Case studies of existing systems and generalized fundamental limits
      Briggs, Justin A.; Atre, Ashwin C.; Dionne, Jennifer A.
      Journal of Applied Physics (Melville, NY, United States) (2013), 113 (12), 124509/1-124509/5CODEN: JAPIAU; ISSN:0021-8979. (American Institute of Physics)
      Upconversion of sub-bandgap photons is a promising approach to exceed the Shockley-Queisser limit in solar technologies. Calcns. have indicated that ideal, upconverter-enhanced cell efficiencies can exceed 44% for non-concd. sunlight, but such improvements have yet to be obsd. exptl. To explain this discrepancy, a thermodn. model is developed of an upconverter-cell considering a highly realistic narrow-band, non-unity-quantum-yield upconverter. As expected, solar cell efficiencies increase with increasing upconverter bandwidth and quantum yield, with max. efficiency enhancements found for near-IR upconverter absorption bands. The model indicates that existing bimol. and lanthanide-based upconverters will not improve cell efficiencies more than 1%, consistent with recent expts. However, the calcns. show that these upconverters can significantly increase cell efficiencies from 28-34% with improved quantum yield, despite their narrow bandwidths. The results highlight the interplay of absorption and quantum yield in upconversion, and provide a platform for optimizing future solar upconverter designs. (c) 2013 American Institute of Physics.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXltVelt7o%253D&md5=a6a2dfb27edcc7ebc091f1cce7fdd6e8
    14. 14
      Cheng, Y. Y.; Fückel, B.; MacQueen, R. W.; Khoury, T.; Clady, R. G. C. R.; Schulze, T. F.; Ekins-Daukes, N. J.; Crossley, M. J.; Stannowski, B.; Lips, K. Improving the light-harvesting of amorphous silicon solar cells with photochemical upconversion Energy Environ. Sci. 2012, 5, 6953 DOI: 10.1039/c2ee21136j
      14
      Improving the light-harvesting of amorphous silicon solar cells with photochemical upconversion
      Cheng, Yuen Yap; Fueckel, Burkhard; MacQueen, Rowan W.; Khoury, Tony; Clady, Raphael G. C. R.; Schulze, Tim F.; Ekins-Daukes, N. J.; Crossley, Maxwell J.; Stannowski, Bernd; Lips, Klaus; Schmidt, Timothy W.
      Energy & Environmental Science (2012), 5 (5), 6953-6959CODEN: EESNBY; ISSN:1754-5706. (Royal Society of Chemistry)
      Single-threshold solar cells are fundamentally limited by their ability to harvest only those photons above a certain energy. Harvesting below-threshold photons and re-radiating this energy at a shorter wavelength would thus boost the efficiency of such devices. We report an increase in light harvesting efficiency of a hydrogenated amorphous silicon (a-Si:H) thin-film solar cell due to a rear up-converter based on sensitized triplet-triplet-annihilation in org. mols. Low energy light in the range 600-750 nm is converted to 550-600 nm light due to the incoherent photochem. process. A peak efficiency enhancement of (1.0 ± 0.2)% at 720 nm is measured under irradn. equiv. to (48 ± 3) suns (AM1.5). We discuss the pathways to be explored in adapting photochem. UC for application in various single threshold devices.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XmsVWqsbk%253D&md5=0c6c2f1c6335ecc9a5e4a7458c648eb9
    15. 15
      Schulze, T. F.; Cheng, Y. Y.; Fuckel, B.; MacQueen, R. W.; Danos, A.; Davis, N. J. L. K.; Tayebjee, M. J. Y.; Khoury, T.; Clady, R. G. C. R.; Ekins-Daukes, N. J. Photochemical upconversion enhanced solar cells: Effect of a back reflector Aust. J. Chem. 2012, 65, 480– 485 DOI: 10.1071/CH12117
      15
      Photochemical Upconversion Enhanced Solar Cells: Effect of a Back Reflector
      Schulze, Tim F.; Cheng, Yuen Yap; Fueckel, Burkhard; MacQueen, Rowan W.; Danos, Andrew; Davis, Nathaniel J. L. K.; Tayebjee, Murad J. Y.; Khoury, Tony; Clady, Raphael G. C. R.; Ekins-Daukes, N. J.; Crossley, Maxwell J.; Stannowski, Bernd; Lips, Klaus; Schmidt, Timothy W.
      Australian Journal of Chemistry (2012), 65 (5), 480-485CODEN: AJCHAS; ISSN:0004-9425. (CSIRO Publishing)
      Photochem. upconversion is applied to a hydrogenated amorphous silicon solar cell in the presence of a back-scattering layer. A custom-synthesized porphyrin was utilized as the sensitizer species, with rubrene as the emitter. Under a bias of 24 suns, a peak external quantum efficiency (EQE) enhancement of ∼ 2% was obsd. at a wavelength of 720 nm. Without the scattering layer, the EQE enhancement was half this value, indicating that the effect of the back-scatterer is to double the efficacy of the upconverting device. The results represent an upconversion figure of merit of 3.5 × 10-4 mAcm-2 sun-2, which is the highest reported to date.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xns1yrsL4%253D&md5=9424f0614d3a4c9daa288e65188b3dc8
    16. 16
      Schulze, T. F.; Czolk, J.; Cheng, Y.-Y.; Fückel, B.; MacQueen, R. W.; Khoury, T.; Crossley, M. J.; Stannowski, B.; Lips, K.; Lemmer, U. Efficiency Enhancement of Organic and Thin-Film Silicon Solar Cells with Photochemical Upconversion J. Phys. Chem. C 2012, 116, 22794– 22801 DOI: 10.1021/jp309636m
      16
      Efficiency enhancement of organic and thin-film silicon solar cells with photochemical upconversion
      Schulze, Tim F.; Czolk, Jens; Cheng, Yuen-Yap; Fuckel, Burkhard; MacQueen, Rowan W.; Khoury, Tony; Crossley, Maxwell J.; Stannowski, Bernd; Lips, Klaus; Lemmer, Uli; Colsmann, Alexander; Schmidt, Timothy W.
      Journal of Physical Chemistry C (2012), 116 (43), 22794-22801CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
      The efficiency of thin-film solar cells with large optical band gaps, such as org. bulk heterojunction or amorphous silicon solar cells, is limited by their inability to harvest the (infra)red part of the solar spectrum. Photochem. upconversion based on triplet-triplet annihilation (TTA-UC) can potentially boost those solar cells by absorbing sub-bandgap photons and coupling the upconverted light back into the solar cell in a spectral region that the cell can efficiently convert into elec. current. In the present study we augment two types of org. solar cells and one amorphous silicon (a-Si:H) solar cell with a TTA-upconverter, demonstrating a solar cell photocurrent increase of up to 0.2% under a moderate concn. (19 suns). The behavior of the org. solar cells, whose augmentation with an upconverting device is so-far unreported, is discussed in comparison to a-Si:H solar cells. Furthermore, on the basis of the TTA rate equations and optical simulations, we assess the potential of TTA-UC augmented solar cells and highlight a strategy for the realization of a device-relevant current increase by TTA-upconversion.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhsVGju7nN&md5=9966a864ffbfdf354950906d44eacf7f
    17. 17
      Kim, J.-h.; Kim, J.-h. Encapsulated TTA-Based Upconversion in the Aqueous Phase for Sub-bandgap Semiconductor Photocatalysis Encapsulated TTA-Based Upconversion in the Aqueous Phase for Sub-bandgap Semiconductor Photocatalysis J. Am. Chem. Soc. 2012, 134, 17478– 17481 DOI: 10.1021/ja308789u
      There is no corresponding record for this reference.
    18. 18
      Khnayzer, R. S.; Blumhoff, J.; Harrington, J. a.; Haefele, A.; Deng, F.; Castellano, F. N. Upconversion-powered photoelectrochemistry Chem. Commun. 2012, 48, 209 DOI: 10.1039/C1CC16015J
      18
      Upconversion of sub-band gap light in solar cell; powered photoelectrochemistry, WO3 nanostructured anode
      Khnayzer, Rony S.; Blumhoff, Joerg; Harrington, Jordan A.; Haefele, Alexandre; Deng, Fan; Castellano, Felix N.
      Chemical Communications (Cambridge, United Kingdom) (2012), 48 (2), 209-211CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
      Upconversion photochem. occurring between palladium II, octaethylporphyrin (PdOEP) and 9,10-diphenylanthracene (DPA) in toluene successfully sensitizes nanostructured WO3 photoanodes (Eg = 2.7 eV) to sub-bandgap non-coherent green photons at low power d.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFGqurfI&md5=624a1edd856e90dc0a789d6fe2e7d9b6
    19. 19
      Nattestad, A.; Cheng, Y.; Macqueen, R.; Schulze, T.; Thompson, F.; Mozer, A.; Fuckel, B.; Khoury, T.; Crossley, M.; Lips, K. Dye-Sensitized Solar Cell with Integrated Triplet Triplet Annihilation Upconversion System J. Phys. Chem. Lett. 2013, 4, 2073– 2078 DOI: 10.1021/jz401050u
      19
      Dye-Sensitized Solar Cell with Integrated Triplet-Triplet Annihilation Upconversion System
      Nattestad, Andrew; Cheng, Yuen Yap; MacQueen, Rowan W.; Schulze, Tim F.; Thompson, Fletcher W.; Mozer, Attila J.; Fuckel, Burkhard; Khoury, Tony; Crossley, Maxwell J.; Lips, Klaus; Wallace, Gordon G.; Schmidt, Timothy W.
      Journal of Physical Chemistry Letters (2013), 4 (12), 2073-2078CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
      Photon upconversion (UC) by triplet-triplet annihilation (TTA-UC) is employed to enhance the response of solar cells to sub-bandgap light. Here, the authors present the 1st report of an integrated photovoltaic device, combining a dye-sensitized solar cell (DSC) and TTA-UC system. The integrated device displays enhanced current under sub-bandgap illumination, resulting in a figure of merit (FoM) under low concn. (3 suns), which is competitive with the best values recorded to date for non-integrated systems. Thus, the authors demonstrate both the compatibility of DSC and TTA-UC and a viable method for device integration.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXptVChsL4%253D&md5=dad3b46ae336db267476b18169e6198b
    20. 20
      Börjesson, K.; Dzebo, D.; Albinsson, B.; Moth-Poulsen, K. Photon upconversion facilitated molecular solar energy storage J. Mater. Chem. A 2013, 1, 8521– 8524 DOI: 10.1039/c3ta12002c
      There is no corresponding record for this reference.
    21. 21
      Gray, V.; Dzebo, D.; Abrahamsson, M.; Albinsson, B.; Moth-Poulsen, K. Triplet-triplet annihilation photon-upconversion: towards solar energy applications Phys. Chem. Chem. Phys. 2014, 16, 10345– 52 DOI: 10.1039/c4cp00744a
      21
      Triplet-triplet annihilation photon-upconversion: towards solar energy applications
      Gray, Victor; Dzebo, Damir; Abrahamsson, Maria; Albinsson, Bo; Moth-Poulsen, Kasper
      Physical Chemistry Chemical Physics (2014), 16 (22), 10345-10352CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
      Solar power prodn. and solar energy storage are important research areas for development of technologies that can facilitate a transition to a future society independent of fossil fuel based energy sources. Devices for direct conversion of solar photons suffer from poor efficiencies due to spectrum losses, which are caused by energy mismatch between the optical absorption of the devices and the broadband irradn. provided by the sun. In this context, photon-upconversion technologies are becoming increasingly interesting since they might offer an efficient way of converting low energy solar energy photons into higher energy photons, ideal for solar power prodn. and solar energy storage. This perspective discusses recent progress in triplet-triplet annihilation (TTA) photon-upconversion systems and devices for solar energy applications. Furthermore, challenges with evaluation of the efficiency of TTA-photon-upconversion systems are discussed and a general approach for evaluation and comparison of existing systems is suggested.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXotFWhsb0%253D&md5=111a2d4f5eb9b403c256ba5b35255de9
    22. 22
      Yanai, N.; Kimizuka, N. Recent emergence of photon upconversion based on triplet energy migration in molecular assemblies Chem. Commun. 2016, 52, 5354– 5370 DOI: 10.1039/C6CC00089D
      22
      Recent emergence of photon upconversion based on triplet energy migration in molecular assemblies
      Yanai, Nobuhiro; Kimizuka, Nobuo
      Chemical Communications (Cambridge, United Kingdom) (2016), 52 (31), 5354-5370CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
      A review. An emerging field of triplet energy migration-based photon upconversion (TEM-UC) is reviewed. Highly efficient photon upconversion has been realized in a wide range of chromophore assemblies, such as non-solvent liqs., ionic liqs., amorphous solids, gels, supramol. assemblies, mol. crystals, and metal-org. frameworks (MOFs). The control over their assembly structures allows for unexpected air-stability and max. upconversion quantum yield at weak solar irradiance that has never been achieved by the conventional mol. diffusion-based mechanism. The introduction of the "self-assembly" concept offers a new perspective in photon upconversion research and triplet exciton science, which show promise for numerous applications ranging from solar energy conversion to chem. biol.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XjslGmur8%253D&md5=4d22fb497b090044c2914ffe081356db
    23. 23
      Mahato, P.; Monguzzi, A.; Yanai, N.; Yamada, T.; Kimizuka, N. Fast and long-range triplet exciton diffusion in metalorganic frameworks for photon upconversion at ultralow excitation power Nat. Mater. 2015, 14, 924– 930 DOI: 10.1038/nmat4366
      There is no corresponding record for this reference.
    24. 24
      Mahato, P.; Yanai, N.; Sindoro, M.; Granick, S.; Kimizuka, N. Preorganized Chromophores Facilitate Triplet Energy Migration, Annihilation and Upconverted Singlet Energy Collection J. Am. Chem. Soc. 2016, 138, 6541– 6549 DOI: 10.1021/jacs.6b01652
      There is no corresponding record for this reference.
    25. 25
      Kozlov, D. V.; Castellano, F. N. Anti-Stokes delayed fluorescence from metal organic bichromophores Chem. Commun. 2004, 1, 2860– 2861 DOI: 10.1039/B412681E
      There is no corresponding record for this reference.
    26. 26
      Bergamini, G.; Ceroni, P.; Fabbrizi, P.; Cicchi, S. A multichromophoric dendrimer: from synthesis to energy up-conversion in a rigid matrix Chem. Commun. 2011, 47, 12780 DOI: 10.1039/c1cc16000a
      26
      A multichromophoric dendrimer: from synthesis to energy up-conversion in a rigid matrix
      Bergamini, Giacomo; Ceroni, Paola; Fabbrizi, Pierangelo; Cicchi, Stefano
      Chemical Communications (Cambridge, United Kingdom) (2011), 47 (48), 12780-12782CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
      A dendrimer (I) with a [Ru(bpy)3]2+ (bpy = 2,2'-bipyridine) complex as a core and four diphenylanthracene units at the periphery was prepd. from a scaffold based on a bipyridyl ligand bearing four terminal alkyne groups. Upon green light excitation, the dendrimer shows blue luminescence even in a rigid matrix at 77 K thanks to the dendritic multichromophoric structure.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFamsLfI&md5=3645f0e78f33358e9efe7a8427fa9ab7
    27. 27
      Tilley, A. J.; Kim, M. J.; Chen, M.; Ghiggino, K. P. Photo-induced energy transfer in ruthenium-centred polymers prepared by a RAFT approach Polymer 2013, 54, 2865– 2872 DOI: 10.1016/j.polymer.2013.03.064
      27
      Photo-induced energy transfer in ruthenium-centered polymers prepared by a RAFT approach
      Tilley, Andrew J.; Kim, Min Jeong; Chen, Ming; Ghiggino, Kenneth P.
      Polymer (2013), 54 (12), 2865-2872CODEN: POLMAG; ISSN:0032-3861. (Elsevier Ltd.)
      Triplet and singlet excitation energy transfer processes are investigated in two novel di- and hexa-functionalized ruthenium centered polymers prepd. by RAFT methods. The polymers consist of a ruthenium tris-bipyridyl ligand complex (Ru(bpy)3) core and pendant polymer 'arms' of 9,10-diphenylanthracene (DPA). Steady state and transient emission and absorption expts. are used to investigate intramol. energy transfer processes following photoexcitation of Ru(bpy)3 and DPA. Triplet energy transfer from the Ru(bpy)3 core to pendant DPA chromophores in the polymer arms is more efficient than the reverse singlet energy transfer process, attributed in part to the long triplet lifetime of Ru(bpy)3 and the polymer structure. A consequence is that intra-polymer chain triplet energy transfer from Ru(bpy)3 to DPA chromophores followed by triplet-triplet annihilation and delayed fluorescence from the DPA can be obsd.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXmtlejur0%253D&md5=4233b8623d180c78553ee05d8f56583f
    28. 28
      Yu, S.; Zeng, Y.; Chen, J.; Yu, T.; Zhang, X.; Yang, G.; Li, Y. Intramolecular triplet-triplet energy transfer enhanced triplet-triplet annihilation upconversion with a short-lived triplet state platinum(II) terpyridyl acetylide photosensitizer RSC Adv. 2015, 5, 70640– 70648 DOI: 10.1039/C5RA12579K
      28
      Intramolecular triplet-triplet energy transfer enhanced triplet-triplet annihilation upconversion with a short-lived triplet state platinum(II) terpyridyl acetylide photosensitizer
      Yu, Shuai; Zeng, Yi; Chen, Jinping; Yu, Tianjun; Zhang, Xiaohui; Yang, Guoqiang; Li, Yi
      RSC Advances (2015), 5 (86), 70640-70648CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)
      A model of a dendritic compd. (Pt-DPA) with two Pt-complex photosensitizer chromophores and two 9,10-diphenylanthracene (DPA) acceptor groups covalently attached to the periphery and the core of the poly(aryl ether) dendrimer of generation 1 was prepd. A triplet-triplet annihilation upconversion (TTA-UC) system (Pt-DPA/DPA-OH) was constructed in deaerated DMF by combining Pt-DPA with a dissociative acceptor (DPA-OH). Although the lifetime of the triplet state of the Pt-complex is only 52 ns, the upconversion fluorescence from DPA (400-460 nm) in the Pt-DPA/DPA-OH system was obsd. with a quantum yield of 0.22% upon selective excitation of the Pt-complex with a 473 nm laser, which is due to the efficient intramol. triplet-triplet energy transfer (ΦTTET > 0.81) from the Pt-complex photosensitizer to the DPA acceptor within Pt-DPA. The acceptor covalently linked with the photosensitizer acts as an energy-relay to transfer the harvested energy to the dissociative acceptor which further undergoes the TTA process. The efficient intramol. triplet-triplet energy transfer process between the photosensitizer and the acceptor plays an important role in the TTA-UC system building with a short-lived triplet state photosensitizer, which facilitates the prodn. of the triplet state of the acceptor, thus advancing the TTA-UC process. This work presents a new strategy for construction of efficient TTA-UC systems utilizing short-lived triplet state photosensitizers.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlajurvO&md5=51ba7cfcbef5a9b963f5d9c5563a951f
    29. 29
      Giribabu, L.; Ashok Kumar, A.; Neeraja, V.; Maiya, B. G. Orientation Dependence of Energy Transfer in an Anthracene-Porphyrin Donor-Acceptor System Angew. Chem. 2001, 113, 3733– 3736 DOI: 10.1002/1521-3757(20011001)113:19<3733::AID-ANGE3733>3.0.CO;2-J
      There is no corresponding record for this reference.
    30. 30
      Harriman, A.; Porter, G.; Richoux, M.-C. Photosensitised reduction of water to hydrogen using water-soluble zinc porphyrins J. Chem. Soc., Faraday Trans. 2 1981, 77, 833 DOI: 10.1039/f29817700833
      30
      Photosensitized reduction of water to hydrogen using water-soluble zinc porphyrins
      Harriman, Anthony; Porter, George; Richoux, Marie Claude
      Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics (1981), 77 (5), 833-44CODEN: JCFTBS; ISSN:0300-9238.
      The report that a pos. charged, H2O-sol. Zn porphyrin photosensitizers the redn. of H2O to H2 with high efficiency (Kalanasundaram, K.; Gratzel, M., 1980) was confirmed. Using Me viologen as electron relay and EDTA as sacrificial donor, the quantum yield (.vphi.) for prodn. of 1/2H2 is ∼0.6. The reaction mechanism involves redn. of Me viologen by triplet porphyrin, the porphyrin π-radical cation being reduced by EDTA. Optimization of the concns. of the reactants for increased prodn. of H2 and limited destruction of porphyrin gave a turnover with respect to the porphyrin of ≤6000. Ways of improving .vphi. and of increasing the fraction of sunlight harvested were considered. The porphyrin π-radical cation may possess the thermodn. capacity to oxidize water to O2.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL3MXktlWjsrk%253D&md5=f5056890e9fa0c2e9f411c6e945fc70b
    31. 31
      Kubista, M.; Sjoback, R.; Albinsson, B. Determination of Equilibrium Constants by chemometric Analysis of Spectroscopic Data Anal. Chem. 1993, 65, 994– 998 DOI: 10.1021/ac00056a008
      There is no corresponding record for this reference.
    32. 32
      Crosby, G. A.; Demas, J. N. The Measurement of Photoluminescence Quantum Yields. A Review J. Phys. Chem. 1971, 75, 991– 1024 DOI: 10.1021/j100678a001
      32
      Measurement of photoluminescence quantum yields. Review
      Crosby, Glenn A.; Demas, James N.
      Journal of Physical Chemistry (1971), 75 (8), 991-1024CODEN: JPCHAX; ISSN:0022-3654.
      A review is given with 147 refs. Methods and apparatus for measuring photoluminescence quantum yields, standards, apparatus calibration, and data corrections are described.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE3MXktFamsL4%253D&md5=5d93e40ea597072c98ab7f195f9cac08
    33. 33
      Heinrich, G.; Schoof, S.; Gusten, H. 9,10-diphenylanthracene as fluorescence quantum yield standard J. Photochem. 1974, 3, 315– 320 DOI: 10.1016/0047-2670(74)80040-7
      33
      9,10-Diphenylanthracene as fluorescence quantum yield standard
      Heinrich, G.; Schoof, S.; Gusten, H.
      Journal of Photochemistry (1974), 3 (4), 315-20CODEN: JPCMAE; ISSN:0047-2670.
      The effect of solvent (Me2CO, C6H6, CHCl3, cyclohexane, Et2O + isopentane + EtOH 5:5:2 by vol (EPA), EtOH, AcOEt, iso-BuOH, isopentane, kerosine, paraffin, petroleum ether, poly(Me methacrylate), and PhMe) and temp. 77-333° K.) on the fluorescent quantum yield from 9,10-diphenylathracene (I) (<10-4 M, degassed) are summarized. The fluorescence decay times, fluorescence quantum yields, triplet-triplet absorption wavelengths, and triplet decay times were detd. for I in soln. in n-C7H16 (298° K), EtOH (77 and 298° K.), C6H6 (198° K.), cyclohexane (298° K.), and EPA (77 and 298° K.). It is 1.00 in all but n-heptane (0.89), EtOH at 298° K. (0.94), and C6H6 (0.96). Quinine sulfate at 25° has a quantum yield of 0.55.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE2MXhtlWnurg%253D&md5=eb96bc45e63a64970d06165bce64fccd
    34. 34
      Magde, D.; Brannon, J. H.; Cremers, T. L.; Olmsted, J. Absolute luminescence yield of cresyl violet. A standard for the red J. Phys. Chem. 1979, 83, 696– 699 DOI: 10.1021/j100469a012
      34
      Absolute luminescence yield of cresyl violet. A standard for the red
      Magde, Douglas; Brannon, James H.; Cremers, Teresa L.; Olmsted, John, III
      Journal of Physical Chemistry (1979), 83 (6), 696-9CODEN: JPCHAX; ISSN:0022-3654.
      The Φf for the oxazine dye cresyl violet is 0.545 in MeOH, at 22 °, for excitation from 540 to 640 nm. With a mean emission wavelength near 638 nm, this should be a useful luminescence quantum yield std. for the red. The abs. accuracy is well within 10% and probably better than 5%. The yield is rather insensitive to conditions even including choice of solvent. It is const. from extreme diln. up to above 10-4 M; but absorption-emission overlap makes it a convenient std. only for relative measurements which use 'dil.' procedures. Two independent and completely different calorimetric methods were used to achieve an abs. measurement which is independent of all previous luminescence yield data: photomicrocalorimetry, an optimized conventional technique, and thermal blooming, a new laser approach.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE1MXhsVeksrw%253D&md5=a0d78bf8219b64c1ad0f768fd5dd2257
    35. 35
      Gray, V.; Dzebo, D.; Lundin, A.; Alborzpour, J.; Abrahamsson, M.; Albinsson, B.; Moth-Poulsen, K. Photophysical characterization of the 9,10-disubstituted anthracene chromophore and its applications in triplet triplet annihilation photon upconversion J. Mater. Chem. C 2015, 3, 11111– 11121 DOI: 10.1039/C5TC02626A
      35
      Photophysical characterization of the 9,10-disubstituted anthracene chromophore and its applications in triplet-triplet annihilation photon upconversion
      Gray, Victor; Dzebo, Damir; Lundin, Angelica; Alborzpour, Jonathan; Abrahamsson, Maria; Albinsson, Bo; Moth-Poulsen, Kasper
      Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2015), 3 (42), 11111-11121CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)
      Mols. based on anthracene are commonly used in applications such as OLEDs and triplet-triplet annihilation upconversion. In future design of blue emitting materials it is useful to know which part of the mol. can be altered to obtain new phys. properties without losing the inherent optical properties. We have studied the effect of substitution of 9,10-substituted anthracenes. Eight anthracenes with arom. Ph and thiophene substituents were synthesized, contg. both electron donating and accepting groups. The substitutions were found to affect the UV/Vis absorption only to a small extent, however the fluorescence properties were more affected with the thiophene substituents that decreased the fluorescence quantum yield from unity to <10%. DFT calcns. confirm the minor change in absorption and indicate that the first and second triplet state energies are also unaffected. Finally the three most fluorescent derivs. 4-(10-phenylanthracene-9-yl)pyridine, 9-phenyl-10-(4-(trifluoromethyl)phenyl)anthracene and 4-(10-phenylanthracene-9-yl)benzonitrile were successfully utilized as annihilators in a triplet-triplet annihilation upconversion (TTA-UC) system employing platinum octaethylporphyrin as the sensitizer. The obsd. upconversion quantum yields, .vphi.UC, slightly exceeded that of the benchmark annihilator 9,10-diphenylanthracene (DPA).
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhsFamtrnF&md5=4480fc4d27e7996ea00566aed2cc235c
    36. 36
      Haefele, A.; Blumhoff, J.; Khnayzer, R. S.; Castellano, F. N. Getting to the (Square) root of the problem: How to make noncoherent pumped upconversion linear J. Phys. Chem. Lett. 2012, 3, 299– 303 DOI: 10.1021/jz300012u
      36
      Getting to the (Square) Root of the Problem: How to Make Noncoherent Pumped Upconversion Linear
      Haefele, Alexandre; Blumhoff, Jorg; Khnayzer, Rony S.; Castellano, Felix N.
      Journal of Physical Chemistry Letters (2012), 3 (3), 299-303CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
      The authors present exptl. data illustrating that photochem. upconversion based on sensitized triplet-triplet annihilation can exhibit anti-Stokes emissions whose intensities with respect to the excitation power can vary between quadratic and linear using a noncoherent polychromatic light source. The benchmark upconverting compn. consisting of Pd(II) octaethylporphyrin (PdOEP) sensitizers and 9,10-diphenylanthracene (DPA) acceptors/annihilators in toluene was selected to generate quadratic, intermediate, and linear behavior under both coherent and noncoherent excitation conditions. Each of these power laws was traversed in a single sample in 1 contiguous expt. through selective pumping of the sensitizer using an Ar+ laser. Wavelength-dependent responses ranging from quadratic to pseudolinear were also recorded from the identical sample compn. when excited by Xe lamp/monochromator output in a conventional fluorometer, where the absorbance at λex dictates the obsd. incident power dependence. Finally, pure linear behavior was derived from noncoherent excitation for the 1st time at higher sensitizer concns.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XlsVCgtQ%253D%253D&md5=d417e89e432352f4a0fb23b1f72911d8
    37. 37
      Lakowicz, J. R. Principles of Fluorescence Spectroscopy, 3rd ed.; Springer Science: New York, 2006.
      There is no corresponding record for this reference.
    38. 38
      Mårtensson, J. Calculation of the Förster orientation factor for donor-acceptor systems with one chromophore of threefold or higher symmetry: zinc porphyrin Chem. Phys. Lett. 1994, 229, 449– 456 DOI: 10.1016/0009-2614(94)01065-X
      38
      Calculation of the Foerster orientation factor for donor-acceptor systems with one chromophore of threefold or higher symmetry: zinc porphyrin
      Martensson, Jerker
      Chemical Physics Letters (1994), 229 (4-5), 449-56CODEN: CHPLBC; ISSN:0009-2614. (Elsevier)
      Three different methods of calcn. of the Foerster orientation factor, κ2, for donor-acceptor systems in which one of the two chromophores have threefold or higher symmetry are discussed. Jablonski's sym. planar oscillator, as well as two perpendicular linear oscillators have been used as models for the transition dipole moment in the highly sym. chromophore. The methods of calcn. are applied to zinc porphyrin-free base porphyrin donor-acceptor systems. The best agreement between exptl. energy transfer rates or efficiencies and those calcd. according to Foerster theory is achieved when κ, not κ2, is calcd. as an av. and then squared. The av. is taken either of an infinite no. of κ-values or of two κ-values, depending on the oscillator model used for the transition dipole moment in the zinc porphyrin.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2MXhslOisbg%253D&md5=83787cbbab4766ef143f03e6be66581e
    39. 39
      Wu, G.-Z.; Gan, W.-X.; Leung, H.-K. Photophysical properties of meso-substituted octaethylporphines and their zinc complexes J. Chem. Soc., Faraday Trans. 1991, 87, 2933 DOI: 10.1039/ft9918702933
      39
      Porphyrin chemistry. 6. Photophysical properties of meso-substituted octaethylporphines and their zinc complexes
      Wu, Guozhang; Gan, Weixing; Leung, Hiukwong
      Journal of the Chemical Society, Faraday Transactions (1991), 87 (18), 2933-7CODEN: JCFTEV; ISSN:0956-5000.
      The absorption and emission spectral properties of a series of meso-substituted octaethylporphines and their Zn complexes were investigated. Changes in electronic absorption spectra induced by the substituents can be explained by M. Gouterman's (1978) 4-orbital model. In order to account fully for the effect of the meso-substituent on the photophys. properties, the steric factor of the meso-substituent has to be taken into consideration.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3MXms1Gktr8%253D&md5=85f60d34307c2f56323dcff5ee83697d
    40. 40
      Eaton, S. S.; Eaton, G. R.; Holm, R. H. Inter- and Intramolecular Ligand Exchange Reactions of Ruthenium(II) Carbonyl Porphine Complexes with Nitrogen Bases J. Organomet. Chem. 1972, 39, 179– 195 DOI: 10.1016/S0022-328X(00)88918-4
      40
      Inter- and intramolecular ligand exchange reactions of ruthenium(II) carbonyl porphine complexes with nitrogen bases
      Eaton, S. S.; Eaton, G. R.; Holm, R. H.
      Journal of Organometallic Chemistry (1972), 39 (1), 179-95CODEN: JORCAI; ISSN:0022-328X.
      To investigate both inter-and intramol. site exchange in coordinated nitrogenous bases the complexes of tetra-cis(p-isopropylphenyl)-porphinatoruthenium carbonyl with 4-tert-butylpyridine, 2-methylpyridine, 3,5-dimethylpyrazole, 4,5-dimethylpyridazine, and 3,6-dimethylpyridazine were studied by total line shape anal. of the variable temp. PMR spectra. Both types of exchange mechanisms were found in these complexes. All of the complexes undergo intermol. ligand exchange at rates ranging from ∼0.09 sec-1 ( G⧺ ∼19 kcal/mol) to 2 × 104 sec-1 ( G ⧺ ∼12 kcal/mol) at 25° for the various complexes, independent of the concn. of excess ligand. Thus the rate detg. step is dissocn. The two pyridazine complexes provide the first examples of intramol. ligand exchange with coordinated nitrogenous bases. The rates at 25° for intramol. site exchange (∼106 and 66 sec-1) are 20-85 times faster than the rates for intermol. ligand exchange in the same complexes. Within exptl. uncertainty there is no intramol. ligand site exchange in the 3,5-dimethylpyrazole complex. Full kinetic and mechanistic details are discussed.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE38Xks1Wjsrs%253D&md5=5dd5318cf8233b06a350ea0f16f1f5a2
    41. 41
      Da Ros, T.; Prato, M.; Guldi, D. M.; Ruzzi, M.; Pasimeni, L. Efficient charge separation in porphyrin-fullerene-ligand complexes Chem. - Eur. J. 2001, 7, 816– 827 DOI: 10.1002/1521-3765(20010216)7:4<816::AID-CHEM816>3.0.CO;2-A
      41
      Efficient charge separation in porphyrin-fullerene-ligand complexes
      Da Ros, Tatiana; Prato, Maurizio; Guldi, Dirk M.; Ruzzi, Marco; Pasimeni, Luigi
      Chemistry - A European Journal (2001), 7 (4), 816-827CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH)
      Photoprocesses assocd. with the complexation of a pyridine-functionalized C60 fullerene deriv. to ruthenium- and zinc-tetraphenylporphyrins (tpp) have been studied by time-resolved optical and transient EPR spectroscopies. It has been found that upon irradn. in toluene, a highly efficient triplet-triplet energy transfer governs the deactivation of the photoexcited [Ru(tpp)] while electron transfer (ET) from the porphyrin to the fullerene prevails in polar solvents. Complexation of [Zn(tpp)] by the fullerene deriv. is reversible and, following excitation of the [Zn(tpp)], gives rise to very efficient charge sepn. In fluid polar solvents such as THF and benzonitrile, radical-ion pairs (RPs) are generated both by intramol. ET inside the complex and by intermol. ET in the uncomplexed form. Charge-sepd. states have lifetimes of about 10 μs in THF and several hundred of microseconds in benzonitrile at room temp.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXhsFWjtLc%253D&md5=fbc31a39f10d6544accef06e5199f427
    42. 42
      Duan, P.; Yanai, N.; Kimizuka, N. Photon upconverting liquids: Matrix-free molecular upconversion systems functioning in air J. Am. Chem. Soc. 2013, 135, 19056– 19059 DOI: 10.1021/ja411316s
      42
      Photon Upconverting Liquids: Matrix-Free Molecular Upconversion Systems Functioning in Air
      Duan, Pengfei; Yanai, Nobuhiro; Kimizuka, Nobuo
      Journal of the American Chemical Society (2013), 135 (51), 19056-19059CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      A nonvolatile, in-air functioning liq. photon upconverting system is developed. A rationally designed triplet sensitizer (branched alkyl chain-modified Pt-(II) porphyrin) is homogeneously doped in energy-harvesting liq. acceptors with a 9,10-diphenylanthracene unit. A significantly high upconversion quantum yield of ∼28% is achieved in the solvent-free liq. state, even under aerated conditions. The liq. upconversion system shows a sequence of efficient triplet energy transfer and migration of two itinerant excited states which eventually collide with each other to produce a singlet excited state of the acceptor. The obsd. insusceptibility of upconversion luminescence to O indicates the sealing ability of molten alkyl chains introduced to liquefy chromophores. The involvement of the energy migration process in triplet-triplet annihilation (TTA) provides a new perspective in designing advanced photon upconversion systems.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhvFegsLbM&md5=908d0aa61c54b0ba1b87619de65d0a84
    43. 43
      Tilley, A. J.; Robotham, B. E.; Steer, R. P.; Ghiggino, K. P. Sensitized non-coherent photon upconversion by intramolecular triplettriplet annihilation in a diphenylanthracene pendant polymer Chem. Phys. Lett. 2015, 618, 198– 202 DOI: 10.1016/j.cplett.2014.11.016
      There is no corresponding record for this reference.
    44. 44
      Hisamitsu, S.; Yanai, N.; Kimizuka, N. Photon-Upconverting Ionic Liquids: Effective Triplet Energy Migration in Contiguous Ionic Chromophore Arrays Angew. Chem., Int. Ed. 2015, 54, 11550– 11554 DOI: 10.1002/anie.201505168
      44
      Photon-upconverting ionic liquids: Effective triplet energy migration in contiguous ionic chromophore arrays
      Hisamitsu, Shota; Yanai, Nobuhiro; Kimizuka, Nobuo
      Angewandte Chemie, International Edition (2015), 54 (39), 11550-11554CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
      Inspired by the bicontinuous ionic-network structure of ionic liqs. (ILs), we developed a new family of photofunctional ILs which show efficient triplet energy migration among contiguously arrayed ionic chromophores. A novel fluorescent IL, comprising an arom. 9,10-diphenylanthracene 2-sulfonate anion and an alkylated phosphonium cation, showed pronounced interactions between chromophores, as revealed by its spectral properties. Upon dissolving a triplet sensitizer, the IL demonstrated photon upconversion based on triplet-triplet annihilation (TTA-UC). Interestingly, the TTA-UC process in the chromophoric IL was optimized at a much lower excitation intensity compared to the previous nonionic liq. TTA-UC system. The superior TTA-UC in this IL system is characterized by a relatively high triplet diffusion const. (1.63×10-6 cm2 s-1) which is ascribed to the presence of ionic chromophore networks in the IL.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlOhurbE&md5=7504edbeb572476002d8084c3fc7c207
    45. 45
      Duan, P.; Yanai, N.; Nagatomi, H.; Kimizuka, N. Photon Upconversion in Supramolecular Gel Matrixes: Spontaneous Accumulation of Light-Harvesting DonorAcceptor Arrays in Nanofibers and Acquired Air Stability J. Am. Chem. Soc. 2015, 137, 1887– 1894 DOI: 10.1021/ja511061h
      There is no corresponding record for this reference.
    46. 46
      Ogawa, T.; Yanai, N.; Monguzzi, A.; Kimizuka, N. Highly Efficient Photon Upconversion in Self-Assembled Light-Harvesting Molecular Systems Sci. Rep. 2015, 5, 10882 DOI: 10.1038/srep10882
      46
      Highly Efficient Photon Upconversion in Self-Assembled Light-Harvesting Molecular Systems
      Ogawa, Taku; Yanai, Nobuhiro; Monguzzi, Angelo; Kimizuka, Nobuo
      Scientific Reports (2015), 5 (), 10882CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)
      To meet the world's demands on the development of sunlight-powered renewable energy prodn., triplet-triplet annihilation-based photon upconversion (TTA-UC) has raised great expectations. However, an ideal highly efficient, low-power, and in-air TTA-UC has not been achieved. Here, we report a novel self-assembly approach to achieve this, which enabled highly efficient TTA-UC even in the presence of oxygen. A newly developed lipophilic 9,10-diphenylanthracene-based emitter mol. functionalized with multiple hydrogen-bonding moieties spontaneously coassembled with a triplet sensitizer in org. media, showing efficient triplet sensitization and subsequent triplet energy migration among the preorganized chromophores. This supramol. light-harvesting system shows a high UC quantum yield of 30% optimized at low excitation power in deaerated conditions. Significantly, the UC emission largely remains even in an air-satd. soln., and this approach is facilely applicable to organogel and solid-film systems.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFyiu7vI&md5=a8c179296f3a11091f96c640812186ba

  • Supporting Information

    Supporting Information

    The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpcc.6b06298.

    • Experimental procedures and characterization of new compounds as well as description of SVD analysis, corresponding spectroscopic data, time-resolved fluorescence, and transient absorption measurements (PDF)


    Terms & Conditions

    Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.