Subtle Molecular Changes Largely Modulate Chiral Helical Assemblies of Achiral Conjugated Polymers by Tuning Solution-State AggregationClick to copy article linkArticle link copied!
- Kyung Sun ParkKyung Sun ParkDepartment of Chemical and Biomolecular Engineering, University of Illinois at Urbana−Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801, United StatesMore by Kyung Sun Park
- Xuyi LuoXuyi LuoDepartment of Chemistry, Purdue University, 560 Oval Dr., West Lafayette, Indiana 47907, United StatesMore by Xuyi Luo
- Justin J. KwokJustin J. KwokDepartment of Materials Science and Engineering, University of Illinois at Urbana−Champaign, 1304 W. Green St., Urbana, Illinois 61801, United StatesMore by Justin J. Kwok
- Azzaya KhasbaatarAzzaya KhasbaatarDepartment of Chemical and Biomolecular Engineering, University of Illinois at Urbana−Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801, United StatesMore by Azzaya Khasbaatar
- Jianguo MeiJianguo MeiDepartment of Chemistry, Purdue University, 560 Oval Dr., West Lafayette, Indiana 47907, United StatesMore by Jianguo Mei
- Ying Diao*Ying Diao*Email: [email protected]Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana−Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801, United StatesDepartment of Materials Science and Engineering, University of Illinois at Urbana−Champaign, 1304 W. Green St., Urbana, Illinois 61801, United StatesBeckman Institute, Molecular Science and Engineering, University of Illinois at Urbana−Champaign, 405 N. Mathews Ave., Urbana, Illinois 61801, United StatesDepartment of Chemistry, University of Illinois at Urbana−Champaign, 505 S. Mathews Ave., Urbana, Illinois 61801, United StatesMaterials Research Laboratory, The Grainger College of Engineering, University of Illinois at Urbana−Champaign, 104 S. Goodwin Ave., Urbana, Illinois 61801, United StatesMore by Ying Diao
Abstract
Understanding the solution-state aggregate structure and the consequent hierarchical assembly of conjugated polymers is crucial for controlling multiscale morphologies during solid thin-film deposition and the resultant electronic properties. However, it remains challenging to comprehend detailed solution aggregate structures of conjugated polymers, let alone their chiral assembly due to the complex aggregation behavior. Herein, we present solution-state aggregate structures and their impact on hierarchical chiral helical assembly using an achiral diketopyrrolopyrrole-quaterthiophene (DPP-T4) copolymer and its two close structural analogues wherein the bithiophene is functionalized with methyl groups (DPP-T2M2) or fluorine atoms (DPP-T2F2). Combining in-depth small-angle X-ray scattering analysis with various microscopic solution imaging techniques, we find distinct aggregate in each DPP solution: (i) semicrystalline 1D fiber aggregates of DPP-T2F2 with a strongly bound internal structure, (ii) semicrystalline 1D fiber aggregates of DPP-T2M2 with a weakly bound internal structure, and (iii) highly crystalline 2D sheet aggregates of DPP-T4. These nanoscopic aggregates develop into lyotropic chiral helical liquid crystal (LC) mesophases at high solution concentrations. Intriguingly, the dimensionality of solution aggregates largely modulates hierarchical chiral helical pitches across nanoscopic to micrometer scales, with the more rigid 2D sheet aggregate of DPP-T4 creating much larger pitch length than the more flexible 1D fiber aggregates. Combining relatively small helical pitch with long-range order, the striped twist-bent mesophase of DPP-T2F2 composed of highly ordered, more rigid 1D fiber aggregate exhibits an anisotropic dissymmetry factor (g-factor) as high as 0.09. This study can be a prominent addition to our knowledge on a solution-state hierarchical assembly of conjugated polymers and, in particular, chiral helical assembly of achiral organic semiconductors that can catalyze an emerging field of chiral (opto)electronics.
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You are free to share(copy and redistribute) this article in any medium or format and to adapt(remix, transform, and build upon) the material for any purpose, even commercially within the parameters below:
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License Summary*
You are free to share(copy and redistribute) this article in any medium or format and to adapt(remix, transform, and build upon) the material for any purpose, even commercially within the parameters below:
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Synopsis
Small changes can have a big impact: Subtle changes in molecular structure of conjugated polymers sensitively tune chiral helical assembly through modulating solution-state aggregation.
Introduction
Results and Discussion
Conclusions
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acscentsci.3c00775.
Materials and methods for polymer synthesis and mesophase samples, experimental details and analysis, as well as additional figures and tables (PDF)
In-situ cross polarized optical microscopy (CPOM) movie of a 100 mg/mL DPP-T2M2 polymer solution monitored during thermal heating and cooling (AVI)
In-situ cross polarized optical microscopy (CPOM) movie of a 100 mg/mL DPP-T4 polymer solution monitored during thermal heating and cooling (AVI)
In-situ cross polarized optical microscopy (CPOM) movie of a 100 mg/mL DPP-T2F2 polymer solution monitored during thermal heating and cooling (AVI)
SAXS model (ZIP)
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.
Acknowledgments
K.S.P., A.K., and Y.D. acknowledge ONR support under Grant No. N00014-22-1-2202. Y.D. also acknowledges partial support by the Air Force Office of Scientific Research (AFOSR) under the Multidisciplinary University Research Initiative (MURI) with grant number FA9550-23-1-0311. K.S.P., J.J.K., and Y.D. acknowledge support by the NSF CAREER award under Grant No. 18-47828. A.K. acknowledges support from A. T. Widiger Chemical Engineering Fellowship. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility, operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC0206CH11357. Extraordinary facility operations were supported in part by the DOE Office of Science through the National Virtual Biotechnology Laboratory, a consortium of DOE national laboratories focused on the response to COVID-19, with funding provided by the Coronavirus CARES Act. This research also used research facilities of the Materials Research Laboratory and Beckman Institute at University of Illinois.
References
This article references 44 other publications.
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- 12Gross, Y. M.; Trefz, D.; Tkachov, R.; Untilova, V.; Brinkmann, M.; Schulz, G. L.; Ludwigs, S. Tuning Aggregation by Regioregularity for High-Performance n-Type P(NDI2OD-T 2) Donor-Acceptor Copolymers. Macromolecules 2017, 50 (14), 5353– 5366, DOI: 10.1021/acs.macromol.7b01386Google Scholar12https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFKmurvN&md5=46d4b879147b16d06f7c7452be94f8b6Tuning Aggregation by Regioregularity for High-Performance n-Type P(NDI2OD-T2) Donor-Acceptor CopolymersGross, Yannic M.; Trefz, Daniel; Tkachov, Roman; Untilova, Viktoriia; Brinkmann, Martin; Schulz, Gisela L.; Ludwigs, SabineMacromolecules (Washington, DC, United States) (2017), 50 (14), 5353-5366CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)We report on the controlled synthesis of naphthalenediimide-bithiophene copolymers with varying ratios of 2,6- and 2,7-linkage (parent polymer: poly{[N,N'-bis(2-octyldodecyl)-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} P(NDI2OD-T2)). Monomers with different ratios of 2,6- and 2,7-regioisomers could be isolated, leading to n-type polymers with tunable regioregularity. With increasing content of 2,7-linkage in the polymer backbone the aggregation tendency can be drastically reduced. Both the redn. behavior and the electron transport properties are very similar for all systems. For the regioregular system we find mobility values of 3 × 10-1 cm2/(V s); the regioirregular systems become comparable with values as high as 7 × 10-2 cm2/(V s) when temp. annealing is employed. This means that regioregularity seems to have an overall lower effect in comparison to classical systems such as poly(3-hexylthiophene). Tuning regioregularity in such systems therefore provides a powerful tool to optimize processing without deteriorating device performance. We even find that device performance of bulk-heterojunction solar cells with a polythiophene deriv. as donor strongly improves upon use of the regioirregular systems.
- 13Chen, M. S.; Lee, O. P.; Niskala, J. R.; Yiu, A. T.; Tassone, C. J.; Schmidt, K.; Beaujuge, P. M.; Onishi, S. S.; Toney, M. F.; Zettl, A. Enhanced Solid-State Order and Field-Effect Hole Mobility through Control of Nanoscale Polymer Aggregation. J. Am. Chem. Soc. 2013, 135 (51), 19229– 19236, DOI: 10.1021/ja4088665Google Scholar13https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhvFSlt7vK&md5=527eff5dc584b4dd812950f12ff55500Enhanced Solid-State Order and Field-Effect Hole Mobility through Control of Nanoscale Polymer AggregationChen, Mark S.; Lee, Olivia P.; Niskala, Jeremy R.; Yiu, Alan T.; Tassone, Christopher J.; Schmidt, Kristin; Beaujuge, Pierre M.; Onishi, Seita S.; Toney, Michael F.; Zettl, Alex; Frechet, Jean M. J.Journal of the American Chemical Society (2013), 135 (51), 19229-19236CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Efficient charge carrier transport in org. field-effect transistors (OFETs) often requires thin films that display long-range order and close π-π packing that is oriented in-plane with the substrate. Although some polymers have achieved high field-effect mobility with such solid-state properties, there are currently few general strategies for controlling the orientation of π-stacking within polymer films. In order to probe structural effects on polymer-packing alignment, furan-contg. diketopyrrolopyrrole (DPP) polymers with similar optoelectronic properties were synthesized with either linear hexadecyl or branched 2-butyloctyl side chains. Differences in polymer soly. were obsd. and attributed to variation in side-chain shape and polymer backbone curvature. Averaged field-effect hole mobilities of the polymers range from 0.19 to 1.82 cm2/V·s, where PDPP3F-C16 is the least sol. polymer and provides the highest max. mobility of 2.25 cm2/V·s. Anal. of the films by AFM and GIXD reveal that less sol. polymers with linear side chains exhibit larger cryst. domains, pack considerably more closely, and align with a greater preference for in-plane π-π packing. Characterization of the polymer solns. prior to spin-coating shows a correlation between early onset nanoscale aggregation and the formation of films with highly oriented in-plane π-stacking. This effect is further obsd. when nonsolvent is added to PDPP3F-BO solns. to induce aggregation, which results in films with increased nanostructural order, in-plane π-π orientation, and field-effect hole mobilities. Since nearly all π-conjugated materials may be coaxed to aggregate, this strategy for enhancing solid-state properties and OFET performance has applicability to a wide variety of org. electronic materials.
- 14Xu, Z.; Park, K. S.; Kwok, J. J.; Lin, O.; Patel, B. B.; Kafle, P.; Davies, D. W.; Chen, Q.; Diao, Y. Not All Aggregates Are Made the Same: Distinct Structures of Solution Aggregates Drastically Modulate Assembly Pathways, Morphology, and Electronic Properties of Conjugated Polymers. Adv. Mater. 2022, 34 (32), 2203055, DOI: 10.1002/adma.202203055Google Scholar14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhvVChtL%252FJ&md5=a83e215be9abb6c52a02263c15158fcbNot All Aggregates Are Made the Same: Distinct Structures of Solution Aggregates Drastically Modulate Assembly Pathways, Morphology, and Electronic Properties of Conjugated PolymersXu, Zhuang; Park, Kyung Sun; Kwok, Justin J.; Lin, Oliver; Patel, Bijal B.; Kafle, Prapti; Davies, Daniel W.; Chen, Qian; Diao, YingAdvanced Materials (Weinheim, Germany) (2022), 34 (32), 2203055CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)Tuning structures of soln.-state aggregation and aggregation-mediated assembly pathways of conjugated polymers is crucial for optimizing their solid-state morphol. and charge-transport property. However, it remains challenging to unravel and control the exact structures of soln. aggregates, let alone to modulate assembly pathways in a controlled fashion. Herein, aggregate structures of an isoindigo-bithiophene-based polymer (PII-2T) are modulated by tuning selectivity of the solvent toward the side chain vs. the backbone, which leads to 3 distinct assembly pathways: direct crystn. from side-chain-assocd. amorphous aggregates, chiral liq. crystal (LC)-mediated assembly from semicryst. aggregates with side-chain and backbone stacking, and random agglomeration from backbone-stacked semicryst. aggregates. Importantly, the amorphous soln. aggregates, compared with semicryst. ones, lead to significantly improved alignment and reduced paracryst. disorder in the solid state due to direct crystn. during the meniscus-guided coating process. Alignment quantified by the dichroic ratio is enhanced by up to 14-fold, and the charge-carrier mobility increases by a max. of 20-fold in films printed from amorphous aggregates compared to those from semicryst. aggregates. By tuning the precise structure of soln. aggregates, the assembly pathways and the resulting thin-film morphol. and device properties can be drastically tuned.
- 15Panzer, F.; Bässler, H.; Köhler, A. Temperature Induced Order-Disorder Transition in Solutions of Conjugated Polymers Probed by Optical Spectroscopy. J. Phys. Chem. Lett. 2017, 8 (1), 114– 125, DOI: 10.1021/acs.jpclett.6b01641Google Scholar15https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitVGntrrO&md5=dea8b0ced6f7350d98aeb1356cfbbbdeTemperature Induced Order-Disorder Transition in Solutions of Conjugated Polymers Probed by Optical SpectroscopyPanzer, Fabian; Baessler, Heinz; Koehler, AnnaJournal of Physical Chemistry Letters (2017), 8 (1), 114-125CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)The aggregation of π-conjugated materials significantly impacts the photophysics and performance of optoelectronic devices. Nevertheless, little is known about the laws governing aggregate formation of π-conjugated materials from soln. In this Perspective, we compare, discuss, and summarize how aggregates form for three different types of compds., i.e., homopolymers, donor-acceptor type polymers, and low mol. wt. compds. To this end, we employ temp.-dependent optical spectroscopy, which is a simple yet powerful tool to study aggregate formation. We show how optical spectra can be analyzed to identify distinct conformational states. We find aggregate formation to proceed the same in all these compds. by a coil-to-globule-like first-order phase transition. Notably, the chain expands before it collapses into a highly ordered dense state. The role of side chains and the impact of changes in environmental polarization are addressed.
- 16Park, Y. D.; Lee, S. G.; Lee, H. S.; Kwak, D.; Lee, D. H.; Cho, K. Solubility-Driven Polythiophene Nanowires and Their Electrical Characteristics. J. Mater. Chem. 2011, 21 (7), 2338– 2343, DOI: 10.1039/C0JM03114CGoogle Scholar16https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtlOisrY%253D&md5=bd2f51c65205f5fe0785ba79cb2041deSolubility-driven polythiophene nanowires and their electrical characteristicsPark, Yeong Don; Lee, Seung Goo; Lee, Hwa Sung; Kwak, Donghoon; Lee, Dae Ho; Cho, KilwonJournal of Materials Chemistry (2011), 21 (7), 2338-2343CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)We demonstrated that interconnected nanofibrillar networks of poly(3-hexylthiophene) (P3HT) thin films with improved crystallinity can be easily fabricated by aging the precursor soln. with marginal solvent. Structural anal. revealed that these benefits arise from the improvements in the crystallinity of P3HT in the precursor soln. At dil. concns., P3HT mols. grew into near-spherical particles during the aging time. As the aging time increased further, P3HT mols. exhibited one-dimensional growth into rod-like structures. At higher P3HT concns. and longer P3HT soln. aging times, dense nanowires were obsd. to form gradually, thereby improving the electronic properties of field-effect transistors (FETs) based on these films. This improvement was due to the change in P3HT organization in the precursor soln. from a random-coil conformation to an ordered aggregate as a result of aging in a marginal solvent, methylene chloride. At high temps., the P3HT mols. were completely solvated and adopted a random-coil conformation, as is obsd. in good solvents. Whereas upon aging the soln. at room temp., methylene chloride poorly solvated the P3HT mols. such that ordered aggregates of P3HT grew in soln., which improved the mol. ordering of P3HT thin films produced from these solns. The field-effect mobility of the thin films was, therefore, enhanced without the need for post-treatments.
- 17Li, M.; Balawi, A. H.; Leenaers, P. J.; Ning, L.; Heintges, G. H. L.; Marszalek, T.; Pisula, W.; Wienk, M. M.; Meskers, S. C. J.; Yi, Y. Impact of Polymorphism on the Optoelectronic Properties of a Low-Bandgap Semiconducting Polymer. Nat. Commun. 2019, 10 (1), 2867, DOI: 10.1038/s41467-019-10519-zGoogle Scholar17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB3MzitF2iuw%253D%253D&md5=769991caf94fba939b15c19387dc0668Impact of polymorphism on the optoelectronic properties of a low-bandgap semiconducting polymerLi Mengmeng; Leenaers Pieter J; Heintges Gael H L; Wienk Martijn M; Meskers Stefan C J; Janssen Rene A J; Li Mengmeng; Janssen Rene A J; Balawi Ahmed Hesham; Laquai Frederic; Ning Lu; Yi Yuanping; Heintges Gael H L; Marszalek Tomasz; Pisula Wojciech; Marszalek Tomasz; Pisula WojciechNature communications (2019), 10 (1), 2867 ISSN:.Polymorphism of organic semiconducting materials exerts critical effects on their physical properties such as optical absorption, emission and electrical conductivity, and provides an excellent platform for investigating structure-property relations. It is, however, challenging to efficiently tune the polymorphism of conjugated polymers in aggregated, semi-crystalline phases due to their conformational freedom and anisotropic nature. Here, two distinctly different semi-crystalline polymorphs (β1 and β2) of a low-bandgap diketopyrrolopyrrole polymer are formed through controlling the solvent quality, as evidenced by spectroscopic, structural, thermal and charge transport studies. Compared to β1, the β2 polymorph exhibits a lower optical band gap, an enhanced photoluminescence, a reduced π-stacking distance, a higher hole mobility in field-effect transistors and improved photocurrent generation in polymer solar cells. The β1 and β2 polymorphs provide insights into the control of polymer self-organization for plastic electronics and hold potential for developing programmable ink formulations for next-generation electronic devices.
- 18Park, K. S.; Xue, Z.; Patel, B. B.; An, H.; Kwok, J. J.; Kafle, P.; Chen, Q.; Shukla, D.; Diao, Y. Chiral Emergence in Multistep Hierarchical Assembly of Achiral Conjugated Polymers. Nat. Commun. 2022, 13 (1), 2738, DOI: 10.1038/s41467-022-30420-6Google Scholar18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xhtlajt73O&md5=bd089ed160718bf9208f2e605d34db7dChiral emergence in multistep hierarchical assembly of achiral conjugated polymersPark, Kyung Sun; Xue, Zhengyuan; Patel, Bijal B.; An, Hyosung; Kwok, Justin J.; Kafle, Prapti; Chen, Qian; Shukla, Diwakar; Diao, YingNature Communications (2022), 13 (1), 2738CODEN: NCAOBW; ISSN:2041-1723. (Nature Portfolio)Intimately connected to the rule of life, chirality remains a long-time fascination in biol., chem., physics and materials science. Chiral structures, e.g., nucleic acid and cholesteric phase developed from chiral mols. are common in nature and synthetic soft materials. While it was recently discovered that achiral but bent-core mesogens can also form chiral helixes, the assembly of chiral microstructures from achiral polymers has rarely been explored. Here, we reveal chiral emergence from achiral conjugated polymers, in which hierarchical helical structures are developed through a multistep assembly pathway. Upon increasing concn. beyond a threshold vol. fraction, dispersed polymer nanofibers form lyotropic liq. cryst. (LC) mesophases with complex, chiral morphologies. Combining imaging, X-ray and spectroscopy techniques with mol. simulations, we demonstrate that this structural evolution arises from torsional polymer mols. which induce multiscale helical assembly, progressing from nano- to micron scale helical structures as the soln. concn. increases. This study unveils a previously unknown complex state of matter for conjugated polymers that can pave way to a field of chiral (opto)electronics. We anticipate that hierarchical chiral helical structures can profoundly impact how conjugated polymers interact with light, transport charges, and transduce signals from biomol. interactions and even give rise to properties unimagined before.
- 19Ariga, K.; Mori, T.; Kitao, T.; Uemura, T. Supramolecular Chiral Nanoarchitectonics. Adv. Mater. 2020, 32 (41), 1905657, DOI: 10.1002/adma.201905657Google Scholar19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXltlers7g%253D&md5=29477ad508aa1f1c71c338359e417912Supramolecular Chiral NanoarchitectonicsAriga, Katsuhiko; Mori, Taizo; Kitao, Takashi; Uemura, TakashiAdvanced Materials (Weinheim, Germany) (2020), 32 (41), 1905657CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Exploration of mol. functions and material properties based on the control of chirality would be a scientifically elegant approach. Here, the fabrication and function of chiral-featured materials from both chiral and achiral components using a supramol. nanoarchitectonics concept are discussed. The contents are classified in to three topics: (i) chiral nanoarchitectonics of rather general mol. assemblies; (ii) chiral nanoarchitectonics of metal-org. frameworks (MOFs); (iii) chiral nanoarchitectonics in liq. crystals. MOF structures are based on nanoscopically well-defined coordinations, while mesoscopic orientations of liq.-cryst. phases are often flexibly altered. Discussion on the effects and features in these representative materials systems with totally different natures reveals the universal importance of supramol. chiral nanoarchitectonics. Amplification of chiral mol. information from mols. to materials-level structures and the creation of chirality from achiral components upon temporal statistic fluctuations are universal, regardless of the nature of the assemblies. These features are thus surely advantageous characteristics for a wide range of applications.
- 20Brandt, J. R.; Salerno, F.; Fuchter, M. J. The Added Value of Small-Molecule Chirality in Technological Applications. Nat. Rev. Chem. 2017, 1 (6), 0045, DOI: 10.1038/s41570-017-0045Google Scholar20https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtVyksb7K&md5=540f1e144f678b544fcd1d14d97dbeedThe added value of small-molecule chirality in technological applicationsBrandt, Jochen R.; Salerno, Francesco; Fuchter, Matthew J.Nature Reviews Chemistry (2017), 1 (6), 0045CODEN: NRCAF7; ISSN:2397-3358. (Nature Research)A review. Chirality is a fundamental symmetry property; chiral objects, such as chiral small mols., exist as a pair of non-superimposable mirror images. Although small-mol. chirality is routinely considered in biol. focused application areas (such as drug discovery and chem. biol.), other areas of scientific development have not considered small-mol. chirality to be central to their approach. In this Review, we highlight recent research in which chirality has enabled advancement in technol. applications. We showcase examples in which the presence of small-mol. chirality is exploited in ways beyond the simple interaction of two different chiral mols.; this can enable the detection and emission of chiral light, help to control mol. motion, or provide a means to control electron spin and bulk charge transport. Thus, we demonstrate that small-mol. chirality is a highly promising avenue for a wide range of technol. oriented scientific endeavours.
- 21Song, I.; Ahn, J.; Ahn, H.; Lee, S. H.; Mei, J.; Kotov, N. A.; Oh, J. H. Helical Polymers for Dissymmetric Circularly Polarized Light Imaging. Nature 2023, 617 (7959), 92– 99, DOI: 10.1038/s41586-023-05877-0Google Scholar21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3sXpt1ejt7w%253D&md5=8f02c49aa36b0125b5829e4dc36c1ff9Helical polymers for dissymmetric circularly polarized light imagingSong, Inho; Ahn, Jaeyong; Ahn, Hyungju; Lee, Sang Hyuk; Mei, Jianguo; Kotov, Nicholas A.; Oh, Joon HakNature (London, United Kingdom) (2023), 617 (7959), 92-99CODEN: NATUAS; ISSN:1476-4687. (Nature Portfolio)Control of the spin angular momentum (SAM) carried in a photon provides a technol. attractive element for next-generation quantum networks and spintronics1-5. However, the weak optical activity and inhomogeneity of thin films from chiral mol. crystals result in high noise and uncertainty in SAM detection. Brittleness of thin mol. crystals represents a further problem for device integration and practical realization of chiroptical quantum devices6-10. Despite considerable successes with highly dissym. optical materials based on chiral nanostructures11-13, the problem of integration of nanochiral materials with optical device platforms remains acute14-16. Here we report a simple yet powerful method to fabricate chiroptical flexible layers via supramol. helical ordering of conjugated polymer chains. Their multiscale chirality and optical activity can be varied across the broad spectral range by chiral templating with volatile enantiomers. After template removal, chromophores remain stacked in one-dimensional helical nanofibrils producing a homogeneous chiroptical layer with drastically enhanced polarization-dependent absorbance, leading to well-resolved detection and visualization of SAM. This study provides a direct path to scalable realization of on-chip detection of the spin degree of freedom of photons necessary for encoded quantum information processing and high-resoln. polarization imaging.
- 22Jiang, S.; Kotov, N. A. Circular Polarized Light Emission in Chiral Inorganic Nanomaterials. Adv. Mater. 2023, 35, 2108431, DOI: 10.1002/adma.202108431Google Scholar22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XlvVentLY%253D&md5=657482e4b4e6caf2a3e372b371de2738Review on circular polarized light emission in chiral inorganic nanomaterialsJiang, Shuang; Kotov, Nicholas A.Advanced Materials (Weinheim, Germany) (2023), 35 (34), 2108431CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Chiral inorg. nanostructures strongly interact with photons changing their polarization state. The resulting circularly polarized light emission (CPLE) has cross-disciplinary importance for a variety of chem./biol. processes and is essential for development of chiral photonics. However, the polarization effects are often complex and their interpretation is dependent on the several structural parameters of the chiral nanostructure. CPLE in nanostructured media has multiple origins and several optical effects are typically convoluted into a single output. Analyzing CPLE data obtained for nanoclusters, nanoparticles, nanoassemblies, and nanocomposites from metals, chalcogenides, perovskite, and other nanostructures, it is shown here that there are several distinct groups of nanomaterials for which CPLE is dominated either by circularly polarized luminescence (CPL) or circularly polarized scattering (CPS); there are also many nanomaterials for which they are comparable. The following points are also demonstrated: (1) CPL and CPS contributions involve light-matter interactions at different structural levels; (2) contribution from CPS is esp. strong for nanostructured microparticles, nanoassemblies, and composites; and (3) engineering of materials with strongly polarized light emission requires synergistic implementation of CPL and CPS effects. These findings are expected to guide development of CPLE materials in a variety of technol. fields, including 3D displays, information storage, biosensors, optical spintronics, and biol. probes.
- 23Ibanez, J. G.; Rincon, M. E.; Gutierrez-Granados, S.; Chahma, M.; Jaramillo-Quintero, O. A.; Frontana-Uribe, B. A. Conducting Polymers in the Fields of Energy, Environmental Remediation, and Chemical-Chiral Sensors. Chem. Rev. 2018, 118 (9), 4731– 4816, DOI: 10.1021/acs.chemrev.7b00482Google Scholar23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXntFahu74%253D&md5=03f5131b5224a87a6fad289799d63c88Conducting Polymers in the Fields of Energy, Environmental Remediation, and Chemical-Chiral SensorsIbanez, Jorge G.; Rincon, Marina. E.; Gutierrez-Granados, Silvia; Chahma, M'hamed; Jaramillo-Quintero, Oscar A.; Frontana-Uribe, Bernardo A.Chemical Reviews (Washington, DC, United States) (2018), 118 (9), 4731-4816CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. Conducting polymers (CPs) thanks to their unique properties, structures made on-demand, new composite mixts. and possibility of deposit on a surface by chem., phys. or electrochem. methodologies, have shown in the last years a renaissance and were widely used in important fields of chem. and materials science. Due to the extensive of the literature of CPs, this review, after a concise introduction about the interrelationship between electrochem. and conducting polymers, it is focused exclusively on the following applications: energy (energy storage devices and solar cells), its use in environmental remediation (anion and cation trapping, electrocatalytic redn./oxidn. of pollutants on CP based electrodes and adsorption of pollutants) and finally electroanal. as chem. sensors in soln., gas phase and chiral mols. This review is expected to be a comprehensive, authoritative, and useful to the chem. community interested in CPs and its applications.
- 24Cai, Y.; Ni, D.; Cheng, W.; Ji, C.; Wang, Y.; Müllen, K.; Su, Z.; Liu, Y.; Chen, C.; Yin, M. Enzyme-Triggered Disassembly of Perylene Monoimide-Based Nanoclusters for Activatable and Deep Photodynamic Therapy. Angew. Chem., Int. Ed. 2020, 59 (33), 14014– 14018, DOI: 10.1002/anie.202001107Google Scholar24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtVahtbfN&md5=b4891f5fdf11eb21830ededc3d814de7Enzyme-Triggered Disassembly of Perylene Monoimide-based Nanoclusters for Activatable and Deep Photodynamic TherapyCai, Yang; Ni, Dongqi; Cheng, Wenyu; Ji, Chendong; Wang, Yaling; Muellen, Klaus; Su, Zhiqiang; Liu, Ying; Chen, Chunying; Yin, MeizhenAngewandte Chemie, International Edition (2020), 59 (33), 14014-14018CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Photodynamic therapy (PDT) exhibits great potential for cancer therapy, but still suffers from nonspecific photosensitivity and poor penetration of photosensitizer. Herein, a smart perylene monoimide-based nanocluster capable of enzyme-triggered disassembly is reported as an activatable and deeply penetrable photosensitizer. A novel carboxylesterase (CE)-responsive tetrachloroperylene monoimide (P1) was synthesized and assembled with folate-decorated albumins into a nanocluster (FHP) with a diam. of circa 100 nm. Once P1 is hydrolyzed by the tumor-specific CE, FHP disassembles into ultrasmall nanoparticles (ca. 10 nm), facilitating the deep tumor penetration of FHP. Furthermore, such enzyme-triggered disassembly of FHP leads to enhanced fluorescence intensity (ca. 8-fold) and elevated singlet oxygen generation ability (ca. 4-fold), enabling in situ near-IR fluorescence imaging and promoted PDT. FHP permits remarkable tumor inhibition in vivo with minimal side effects through imaging-guided, activatable, and deep PDT. This work confirms that this cascaded multifunctional control through enzyme-triggered mol. disassembly is an effective strategy for precise cancer theranostics.
- 25Yang, Y.; da Costa, R. C.; Fuchter, M. J.; Campbell, A. J. Circularly Polarized Light Detection by a Chiral Organic Semiconductor Transistor. Nature Photon 2013, 7 (8), 634– 638, DOI: 10.1038/nphoton.2013.176Google ScholarThere is no corresponding record for this reference.
- 26Wade, J.; Hilfiker, J. N.; Brandt, J. R.; Liirò-Peluso, L.; Wan, L.; Shi, X.; Salerno, F.; Ryan, S. T. J.; Schöche, S.; Arteaga, O. Natural Optical Activity as the Origin of the Large Chiroptical Properties in π-Conjugated Polymer Thin Films. Nat. Commun. 2020, 11 (1), 6137, DOI: 10.1038/s41467-020-19951-yGoogle Scholar29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisFWks7zJ&md5=0ac57f810b34b06d04520eac31fd5245Natural optical activity as the origin of the large chiroptical properties in π-conjugated polymer thin filmsWade, Jessica; Hilfiker, James N.; Brandt, Jochen R.; Liiro-Peluso, Letizia; Wan, Li; Shi, Xingyuan; Salerno, Francesco; Ryan, Sean T. J.; Schoche, Stefan; Arteaga, Oriol; Javorfi, Tamas; Siligardi, Giuliano; Wang, Cheng; Amabilino, David B.; Beton, Peter H.; Campbell, Alasdair J.; Fuchter, Matthew J.Nature Communications (2020), 11 (1), 6137CODEN: NCAOBW; ISSN:2041-1723. (Nature Research)Polymer thin films that emit and absorb circularly polarised light have been demonstrated with the promise of achieving important technol. advances; from efficient, high-performance displays, to 3D imaging and all-org. spintronic devices. However, the origin of the large chiroptical effects in such films has, until now, remained elusive. We investigate the emergence of such phenomena in achiral polymers blended with a chiral small-mol. additive (1-aza[6]helicene) and intrinsically chiral-sidechain polymers using a combination of spectroscopic methods and structural probes. We show that - under conditions relevant for device fabrication - the large chiroptical effects are caused by magneto-elec. coupling (natural optical activity), not structural chirality as previously assumed, and may occur because of local order in a cylinder blue phase-type organization. This disruptive mechanistic insight into chiral polymer thin films will offer new approaches towards chiroptical materials development after almost three decades of research in this area.
- 27Han, M. J.; Yun, H. S.; Cho, Y.; Kim, M.; Yang, C.; Tsukruk, V. V.; Yoon, D. K. Chiral Optoelectronic Functionalities via DNA-Organic Semiconductor Complex. ACS Nano 2021, 15 (12), 20353– 20363, DOI: 10.1021/acsnano.1c08641Google Scholar30https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXis1OgsLzJ&md5=9b6f14340fe11cfe3190ce04a7c7830bChiral optoelectronic functionalities via DNA-organic semiconductor complexHan, Moon Jong; Yun, Hee Seong; Cho, Yongjoon; Kim, Minkyu; Yang, Changduk; Tsukruk, Vladimir V.; Yoon, Dong KiACS Nano (2021), 15 (12), 20353-20363CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)We fabricate the bio-org. field-effect transistor (BOFET) with the DNA-perylene diimide (PDI) complex, which shows unusual chiroptical and elec. functionalities. DNA is used as the chirality-inducing scaffold and the charge-injection layer. The shear-oriented film of the DNA-PDI complex shows how the large-area periodic mol. orientation and the charge transport are related, generating drastically different optoelectronic properties at each DNA/PDI concn. The resultant BOFET reveals chiral structures with a high charge carrier mobility, photoresponsivity, and photosensitivity, reaching 3.97 cm2 V-1 s-1, 1.18 A W-1, and 7.76 × 103, resp. Interestingly, the BOFET enables the definitive response under the handedness of circularly polarized light with a high dissymmetry factor of approx. +0.14. This work highlights the natural chirality and anisotropy of DNA material and the electron cond. of org. semiconducting mols. to be mutually used in significant chiro-optoelectronic functions as an added ability to the traditional OFET.
- 28Kulkarni, C.; Meskers, S. C. J.; Palmans, A. R. A.; Meijer, E. W. Amplifying Chiroptical Properties of Conjugated Polymer Thin-Film Using an Achiral Additive. Macromolecules 2018, 51 (15), 5883– 5890, DOI: 10.1021/acs.macromol.8b01077Google Scholar31https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtlOqsb3P&md5=e0ef5e27400a349ababe95e5e7873ff1Amplifying Chiroptical Properties of Conjugated Polymer Thin-Film Using an Achiral AdditiveKulkarni, Chidambar; Meskers, Stefan C. J.; Palmans, Anja R. A.; Meijer, E. W.Macromolecules (Washington, DC, United States) (2018), 51 (15), 5883-5890CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)Chiral conjugated polymers bearing enantiopure side chains offer the possibility to harness the effect of chirality in org. electronic devices. However, its use is hampered by the low degree of circular polarization in absorption (gabs) in most of the conjugated polymer thin-films studied. Here we demonstrate a versatile method to significantly increase the gabs by using a few wt. percentages of a com. available achiral long-chain alc. as an additive. This additive enhances the chiroptical properties in both absorption and emission by ca. 5-10 times in the thin-films. We envisage that the alc. additive acts as a plasticizer which enhances the long-range chiral liq. cryst. ordering of the polymer chains, thereby amplifying the chiroptical properties in the thin-film. The application of this methodol. to various conjugated polymers has been demonstrated.
- 29Chochos, C. L.; Katsouras, A.; Drakopoulou, S.; Miskaki, C.; Krassas, M.; Tzourmpakis, P.; Kakavelakis, G.; Sprau, C.; Colsmann, A.; Squeo, B. M. Effects of Alkyl Side Chains Positioning and Presence of Fused Aromatic Units in the Backbone of Low-Bandgap Diketopyrrolopyrrole Copolymers on the Optoelectronic Properties of Organic Solar Cells. J. Polym. Sci., Part A: Polym. Chem. 2018, 56 (1), 138– 146, DOI: 10.1002/pola.28901Google Scholar32https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhslGkt7%252FP&md5=f28785f17da0b66f200b92e50582ea4dEffects of alkyl side chains positioning and presence of fused aromatic units in the backbone of low-bandgap diketopyrrolopyrrole copolymers on the optoelectronic properties of organic solar cellsChochos, Christos L.; Katsouras, Athanasios; Drakopoulou, Sofia; Miskaki, Christina; Krassas, Miron; Tzourmpakis, Pavlos; Kakavelakis, George; Sprau, Christian; Colsmann, Alexander; Squeo, Benedetta M.; Gregoriou, Vasilis G.; Kymakis, Emmanuel; Avgeropoulos, ApostolosJournal of Polymer Science, Part A: Polymer Chemistry (2018), 56 (1), 138-146CODEN: JPACEC; ISSN:0887-624X. (John Wiley & Sons, Inc.)The systematic optimization of the chem. structure of low-bandgap (LBG) donor-acceptor polymeric semiconductors is a challenging task for which accurate guidelines are yet to be detd. Several different structural and mol. parameters are crucial ingredients for obtaining LBG polymers that simultaneously possess high power conversion efficiencies, good processability in common org. solvents, and enhanced stability in org. photovoltaic devices. In this work, we present an extensive structure-optoelectronic properties-solar cell performance study on the emerging class of diketopyrrolopyrrole-based LBG polymers. In particular, we investigate alkyl side chain positioning by introducing linear alkyl side chains into two different positions (α- and β-), and the distance of the electron rich and electron deficient monomers within the repeat units of the polymer chain. We demonstrate that anchoring linear alkyl side chains to the α-positions and introducing fused moieties into the polymer backbone, can be beneficial toward maintaining photocurrents similar to the unsubstituted deriv., and concurrently exhibit better processabiliy in common org. solvents. These results can provide a design rationale towards further optimization of semiconducting polymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017.
- 30Zhang, A.; Xiao, C.; Wu, Y.; Li, C.; Ji, Y.; Li, L.; Hu, W.; Wang, Z.; Ma, W.; Li, W. Effect of Fluorination on Molecular Orientation of Conjugated Polymers in High Performance Field-Effect Transistors. Macromolecules 2016, 49 (17), 6431– 6438, DOI: 10.1021/acs.macromol.6b01446Google Scholar33https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhsVektr%252FF&md5=427d800606625375b3b229a3ccf20b00Effect of Fluorination on Molecular Orientation of Conjugated Polymers in High Performance Field-Effect TransistorsZhang, Andong; Xiao, Chengyi; Wu, Yang; Li, Cheng; Ji, Yunjing; Li, Lin; Hu, Wenping; Wang, Zhaohui; Ma, Wei; Li, WeiweiMacromolecules (Washington, DC, United States) (2016), 49 (17), 6431-6438CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)Fluorinated conjugated polymers have been widely used in high performance polymer solar cells, but they showed limited application in field-effect transistors (FETs). In this paper, we focus on the influence of fluorine atoms upon charge transport of conjugated polymers in FET devices. Two series of conjugated polymers without or with fluorine atoms were designed and applied into FETs. Nonfluorinated conjugated polymers show high hole mobilities up to 11.16 cm2 V-1 s-1, while fluorinated polymers exhibit low hole mobilities below 1.80 cm2 V-1 s-1. Further investigation by differential scanning calorimetry (DSC) and 2D grazing-incidence wide-angle X-ray scattering (2D-GIWAXS) reveal that fluorinated conjugated polymers show low crystallinity and "face-on" orientation in thin films, explaining their poor hole mobilities in FET devices. Our results clearly show how the chem. structures influence the charge transport properties, which can be used to design new conjugated polymers toward high performance FETs.
- 31Abdelsamie, M.; Chaney, T. P.; Yan, H.; Schneider, S. A.; Ayhan, I. A.; Gomez, E. D.; Reynolds, J. R.; Toney, M. F. Revealing Temperature-Dependent Polymer Aggregation in Solution with Small-Angle X-Ray Scattering. J. Mater. Chem. A 2022, 10 (4), 2096– 2104, DOI: 10.1039/D1TA09086KGoogle Scholar34https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XpvFCjsQ%253D%253D&md5=185dba35949e04e7142eb6ff1bf9fdaeRevealing temperature-dependent polymer aggregation in solution with small-angle X-ray scatteringAbdelsamie, Maged; Chaney, Thomas P.; Yan, Hongping; Schneider, Sebastian A.; Ayhan, I. Alperen; Gomez, Enrique D.; Reynolds, John R.; Toney, Michael F.Journal of Materials Chemistry A: Materials for Energy and Sustainability (2022), 10 (4), 2096-2104CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)Improving the morphol. of bulk heterojunction active layers remains a primary challenge for org. photovoltaics (OPVs), and much research has been devoted to achieving this through modifying OPV casting solns. to control film formation and crystallinity. Yet, the soln. conformation of conjugated polymers used in OPVs is largely unknown. Here, we report observations of temp. dependent aggregation (TDA) through small-angle X-ray scattering (SAXS) investigations of polymer conformation in chlorobenzene : dichlorobenzene casting solvent as a function of temp. for PffBT4T-2OD, a polymer known to display TDA, and its deriv. PffBT3T-2OD which displays significantly reduced TDA. We find that, upon cooling below 80°C, PffBT4T-2OD forms large cryst. aggregates in soln., while its deriv. PffBT3T-2OD forms mostly amorphous aggregates of similar size with some evidence of short-range order. This change in soln. aggregation behavior is reflected in the lack of gelation by PffBT3T-2OD upon film deposition by spin coating. Grazing-incidence wide-angle X-ray scattering (GIWAXS) revealed a preferred face-on π-π stacking orientation for PffBT3T-2OD films while PffBT4T-2OD's π-π stacking peak was isotropic. We combine these findings to suggest that the presence of cryst. seed aggregates in PffBT4T-2OD soln. quickly form an isotropic crystallite network upon cooling while PffBT3T-2OD's amorphous aggregates more slowly crystallize resulting in improved processability of PffBT3T-2OD.
- 32Kwok, J. J.; Park, K. S.; Patel, B. B.; Dilmurat, R.; Beljonne, D.; Zuo, X.; Lee, B.; Diao, Y. Understanding Solution State Conformation and Aggregate Structure of Conjugated Polymers via Small Angle X-Ray Scattering. Macromolecules 2022, 55 (11), 4353– 4366, DOI: 10.1021/acs.macromol.1c02449Google Scholar35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhtlWis7%252FO&md5=e7e54ed95b767f51d69f99bc8eb75e9dUnderstanding Solution State Conformation and Aggregate Structure of Conjugated Polymers via Small Angle X-ray ScatteringKwok, Justin J.; Park, Kyung Sun; Patel, Bijal B.; Dilmurat, Rishat; Beljonne, David; Zuo, Xiaobing; Lee, Byeongdu; Diao, YingMacromolecules (Washington, DC, United States) (2022), 55 (11), 4353-4366CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)Donor-acceptor (D-A) conjugated polymers are high-performance org. electronic materials that exhibit complex aggregation behavior. Understanding the soln. state conformation and aggregation of conjugated polymers is crucial for controlling morphol. during thin-film deposition and the subsequent electronic performance. However, a precise multiscale structure of soln. state aggregates is lacking. Here, we present an in-depth small-angle X-ray scattering (SAXS) anal. of the soln. state structure of an isoindigo-bithiophene-based D-A polymer (PII-2T) in chlorobenzene and decane as our primary system. Modeling the system as a combination of hierarchical fibrillar aggregates mixed with dispersed polymers, we ext. information about conformation and multiscale aggregation and also clarify the phys. origin of features often obsd. but unaddressed or misinterpreted in small-angle scattering patterns of conjugated polymers. The persistence length of the D-A polymer extd. from SAXS agrees well with a theor. model based on the dihedral potentials. Addnl., we show that the broad high q structure factor peak seen in scattering profiles can be attributed to lamellar stacking occurring within the fibril aggregates and that the low q aggregate scattering is strongly influenced by the polymer mol. wt. Overall, the SAXS profiles of D-A polymers in general exhibit a sensitive dependence on the co-existence of fibrillar aggregate and dispersed polymer chain populations. We corroborate our findings from SAXS with electron microscopy of freeze-dried samples for direct imaging of fibrillar aggregates. Finally, we demonstrate the generality of our approach by fitting the scattering profiles of a variety of D-A polymers based on thieno-isoindigo (PTII-2T), diketopyrrolopyrrole (DPP2T-TT, DPP-BTZ, PDPP2FT-C16), naphthalenediimide (P(NDI2OD-T2)), and a conjugated block copolymer P3HT-b-DPPT-T. The results presented here establish a picture of the D-A polymer soln. state structure and provide a general method of interpreting and analyzing their scattering profiles.
- 33Albano, G.; Pescitelli, G.; Di Bari, L. Chiroptical Properties in Thin Films of π-Conjugated Systems. Chem. Rev. 2020, 120 (18), 10145– 10243, DOI: 10.1021/acs.chemrev.0c00195Google Scholar36https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhslCjsb3M&md5=22166eb37a9a7a4ef769e7de4a7345cdChiroptical Properties in Thin Films of π-Conjugated SystemsAlbano, Gianluigi; Pescitelli, Gennaro; Di Bari, LorenzoChemical Reviews (Washington, DC, United States) (2020), 120 (18), 10145-10243CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. Chiral π-conjugated mols. provide new materials with outstanding features for current and perspective applications, esp. in the field of optoelectronic devices. In thin films, processes such as charge conduction, light absorption, and emission are governed not only by the structure of the individual mols. but also by their supramol. structures and intermol. interactions to a large extent. Electronic CD, ECD, and its emission counterpart, circularly polarized luminescence, CPL, provide tools for studying aggregated states and the key properties to be sought for designing innovative devices. In this review, we shall present a comprehensive coverage of chiroptical properties measured on thin films of org. π-conjugated mols. In the first part, we shall discuss some general concepts of ECD, CPL, and other chiroptical spectroscopies, with a focus on their applications to thin film samples. In the following, we will overview the existing literature on chiral π-conjugated systems whose thin films have been characterized by ECD and/or CPL, as well other chiroptical spectroscopies. Special emphasis will be put on systems with large dissymmetry factors (gabs and glum) and on the application of ECD and CPL to derive structural information on aggregated states.
- 34Pescitelli, G.; Omar, O. H.; Operamolla, A.; Farinola, G. M.; Di Bari, L. Chiroptical Properties of Glucose-Substituted Poly(p-Phenylene-Ethynylene)s in Solution and Aggregate State. Macromolecules 2012, 45 (24), 9626– 9630, DOI: 10.1021/ma301919uGoogle Scholar37https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhvVahsLzI&md5=6060c1de49e4ec59d2686ec9c508b87cChiroptical Properties of Glucose-Substituted Poly(p-phenylene-ethynylene)s in Solution and Aggregate StatePescitelli, Gennaro; Omar, Omar Hassan; Operamolla, Alessandra; Farinola, Gianluca M.; Di Bari, LorenzoMacromolecules (Washington, DC, United States) (2012), 45 (24), 9626-9630CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)The aggregation behavior of two D-glucose-substituted phenyleneethynylenes, an alternate oligomeric copolymer (AP) and a oligomeric homopolymer (HO), was investigated by means of UV-vis absorption, CD (CD) and fluorescence spectroscopy. CD reveals superior capability to detect the early stages of aggregation and to provide information about aggregate geometries. The multiband CD spectrum of the AP and of analogous chiral PPEs is rationalized on the basis of the exciton coupling between vibronic transitions localized on proximate portions of the chromophoric chains.
- 35Lu, J.; Xue, Y.; Bernardino, K.; Zhang, N.-N.; Gomes, W. R.; Ramesar, N. S.; Liu, S.; Hu, Z.; Sun, T.; de Moura, A. F. Enhanced Optical Asymmetry in Supramolecular Chiroplasmonic Assemblies with Long-Range Order. Science 2021, 371 (6536), 1368– 1374, DOI: 10.1126/science.abd8576Google Scholar38https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXnsVyqt7c%253D&md5=ba0509166c9a8d6cb7d64f6c0af1bf79Enhanced optical asymmetry in supramolecular chiroplasmonic assemblies with long-range orderLu, Jun; Xue, Yao; Bernardino, Kalil; Zhang, Ning-Ning; Gomes, Weverson R.; Ramesar, Naomi S.; Liu, Shuhan; Hu, Zheng; Sun, Tianmeng; de Moura, Andre Farias; Kotov, Nicholas A.; Liu, KunScience (Washington, DC, United States) (2021), 371 (6536), 1368-1374CODEN: SCIEAS; ISSN:1095-9203. (American Association for the Advancement of Science)Chiral assemblies of plasmonic nanoparticles are known for strong CD but not for high optical asymmetry, which is limited by the unfavorable combination of elec. and magnetic field components compounded by strong scattering. Here, we show that these limitations can be overcome by the long-range organization of nanoparticles in a manner similar to the liq. crystals and found in helical assemblies of gold nanorods with human islet amyloid polypeptides. A strong, polarization-dependent spectral shift and the reduced scattering of energy states with antiparallel orientation of dipoles activated in assembled helixes increased optical asymmetry g-factors by a factor of more than 4600. The liq. crystal-like color variations and the nanorod-accelerated fibrillation enable drug screening in complex biol. media. Improvement of long-range order can also provide structural guidance for the design of materials with high optical asymmetry.
- 36Prinsen, P.; Van Der Schoot, P. Shape and Director-Field Transformation of Tactoids. Phys. Rev. E 2003, 68 (2), 021701, DOI: 10.1103/PhysRevE.68.021701Google Scholar39https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXntFaisr4%253D&md5=4e26d7c0989b8c9f95bfc3328f3720ffShape and director-field transformation of tactoidsPrinsen, Peter; van der Schoot, PaulPhysical Review E: Statistical, Nonlinear, and Soft Matter Physics (2003), 68 (2-1), 021701/1-021701/11CODEN: PRESCM ISSN:. (American Physical Society)Tactoids are droplets of a nematic phase that under suitable conditions form in dispersions of elongated colloidal particles. The authors theor. study the shape and the director-field configuration of such droplets for the case where a planar anchoring of the director field to the interface is favored. A min. of four regimes can be identified in which the droplets have a different structure. Large droplets tend to be nearly spherical with a director field that is bipolar if the surface tension is strongly anisotropic and homogeneous if this is not so. Small droplets can become very elongated and spindlelike if the surface tension is sufficiently anisotropic. Depending on the anchoring strength, the director field is then either homogeneous or bipolar. The more elongated the tactoid, the more strongly it resists the crossing over from a homogeneous to a bipolar structure. This should have implications for the nucleation rate of the nematic phase. The authors' calcns. qual. describe the size dependence of the aspect ratio of tactoids found in recent expts.
- 37Weirich, K. L.; Banerjee, S.; Dasbiswas, K.; Witten, T. A.; Vaikuntanathan, S.; Gardel, M. L. Liquid Behavior of Cross-Linked Actin Bundles. Proc. Natl. Acad. Sci. U. S. A. 2017, 114 (9), 2131– 2136, DOI: 10.1073/pnas.1616133114Google Scholar40https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXislWgsb8%253D&md5=f4d4386152e8b75505ee77d71f376c23Liquid behavior of cross-linked actin bundlesWeirich, Kimberly L.; Banerjee, Shiladitya; Dasbiswas, Kinjal; Witten, Thomas A.; Vaikuntanathan, Suriyanarayanan; Gardel, Margaret L.Proceedings of the National Academy of Sciences of the United States of America (2017), 114 (9), 2131-2136CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)The actin cytoskeleton is a crit. regulator of cytoplasmic architecture and mechanics, essential in a myriad of physiol. processes. Here we demonstrate a liq. phase of actin filaments in the presence of the physiol. cross-linker, filamin. Filamin condenses short actin filaments into spindle-shaped droplets, or tactoids, with shape dynamics consistent with a continuum model of anisotropic liqs. We find that cross-linker d. controls the droplet shape and deformation timescales, consistent with a variable interfacial tension and viscosity. Near the liq.-solid transition, cross-linked actin bundles show behaviors reminiscent of fluid threads, including capillary instabilities and contraction. These data reveal a liq. droplet phase of actin, demixed from the surrounding soln. and dominated by interfacial tension. These results suggest a mechanism to control organization, morphol., and dynamics of the actin cytoskeleton.
- 38Verhoeff, A. A.; Bakelaar, I. A.; Otten, R. H. J.; Van Der Schoot, P.; Lekkerkerker, H. N. W. Tactoids of Plate-Like Particles: Size, Shape, and Director Field. Langmuir 2011, 27 (1), 116– 125, DOI: 10.1021/la104128mGoogle Scholar41https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhsFSkurfL&md5=15ec962c5c655aa20a2cf61efbcb73c2Tactoids of plate-like particles: size, shape, and director fieldVerhoeff, A. A.; Bakelaar, I. A.; Otten, R. H. J.; van der Schoot, P.; Lekkerkerker, H. N. W.Langmuir (2011), 27 (1), 116-125CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)We studied, by means of polarized light microscopy, the shape and director field of nematic tactoids as a function of their size in dispersions of colloidal gibbsite platelets in polar and apolar solvents. Because of the homeotropic anchoring of the platelets to the interface, we found large tactoids to be spherical with a radial director field, whereas small tactoids turn out to have an oblate shape and a homogeneous director field, in accordance with theor. predictions. The transition from a radial to a homogeneous director field seems to proceed via two different routes depending in our case on the solvent. In one route, the what presumably is a hedgehog point defect in the center of the tactoid transforms into a ring defect with a radius that presumably goes to infinity with decreasing drop size. In the other route, the hedgehog defect is displaced from the center to the edge of the tactoid, where it becomes virtual again going to infinity with decreasing drop size. Furthermore, quant. anal. of the tactoid properties provides us with useful information on the ratio of the splay elastic const. and the anchoring strength and the ratio of the anchoring strength and the surface tension.
- 39Sutton, C.; Körzdörfer, T.; Gray, M. T.; Brunsfeld, M.; Parrish, R. M.; Sherrill, C. D.; Sears, J. S.; Brédas, J.-L. Accurate Description of Torsion Potentials in Conjugated Polymers Using Density Functionals with Reduced Self-Interaction Error. J. Chem. Phys. 2014, 140 (5), 054310, DOI: 10.1063/1.4863218Google Scholar42https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXjslOksL0%253D&md5=fb3aca3d1b5e96451f9f711e051d3069Accurate description of torsion potentials in conjugated polymers using density functionals with reduced self-interaction errorSutton, Christopher; Korzdorfer, Thomas; Gray, Matthew T.; Brunsfeld, Max; Parrish, Robert M.; Sherrill, C. David; Sears, John S.; Bredas, Jean-LucJournal of Chemical Physics (2014), 140 (5), 054310/1-054310/9CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)We investigate the torsion potentials in two prototypical π-conjugated polymers, polyacetylene and polydiacetylene, as a function of chain length using different flavors of d. functional theory. Our study provides a quant. anal. of the delocalization error in std. semilocal and hybrid d. functionals and demonstrates how it can influence structural and thermodn. properties. The delocalization error is quantified by evaluating the many-electron self-interaction error (MESIE) for fractional electron nos., which allows us to establish a direct connection between the MESIE and the error in the torsion barriers. The use of non-empirically tuned long-range cor. hybrid functionals results in a very significant redn. of the MESIE and leads to an improved description of torsion barrier heights. In addn., we demonstrate how our anal. allows the detn. of the effective conjugation length in polyacetylene and polydiacetylene chains. (c) 2014 American Institute of Physics.
- 40Körzdörfer, T.; Brédas, J.-L. Organic Electronic Materials: Recent Advances in the DFT Description of the Ground and Excited States Using Tuned Range-Separated Hybrid Functionals. Acc. Chem. Res. 2014, 47 (11), 3284– 3291, DOI: 10.1021/ar500021tGoogle Scholar43https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2cnosFaltg%253D%253D&md5=378dd3ab4b06d00152d606ed0f7c933fOrganic electronic materials: recent advances in the DFT description of the ground and excited states using tuned range-separated hybrid functionalsKorzdorfer Thomas; Bredas Jean-LucAccounts of chemical research (2014), 47 (11), 3284-91 ISSN:.CONSPECTUS: Density functional theory (DFT) and its time-dependent extension (TD-DFT) are powerful tools enabling the theoretical prediction of the ground- and excited-state properties of organic electronic materials with reasonable accuracy at affordable computational costs. Due to their excellent accuracy-to-numerical-costs ratio, semilocal and global hybrid functionals such as B3LYP have become the workhorse for geometry optimizations and the prediction of vibrational spectra in modern theoretical organic chemistry. Despite the overwhelming success of these out-of-the-box functionals for such applications, the computational treatment of electronic and structural properties that are of particular interest in organic electronic materials sometimes reveals severe and qualitative failures of such functionals. Important examples include the overestimation of conjugation, torsional barriers, and electronic coupling as well as the underestimation of bond-length alternations or excited-state energies in low-band-gap polymers. In this Account, we highlight how these failures can be traced back to the delocalization error inherent to semilocal and global hybrid functionals, which leads to the spurious delocalization of electron densities and an overestimation of conjugation. The delocalization error for systems and functionals of interest can be quantified by allowing for fractional occupation of the highest occupied molecular orbital. It can be minimized by using long-range corrected hybrid functionals and a nonempirical tuning procedure for the range-separation parameter. We then review the benefits and drawbacks of using tuned long-range corrected hybrid functionals for the description of the ground and excited states of π-conjugated systems. In particular, we show that this approach provides for robust and efficient means of characterizing the electronic couplings in organic mixed-valence systems, for the calculation of accurate torsional barriers at the polymer limit, and for the reliable prediction of the optical absorption spectrum of low-band-gap polymers. We also explain why the use of standard, out-of-the-box range-separation parameters is not recommended for the DFT and/or TD-DFT description of the ground and excited states of extended, pi-conjugated systems. Finally, we highlight a severe drawback of tuned range-separated hybrid functionals by discussing the example of the calculation of bond-length alternation in polyacetylene, which leads us to point out the challenges for future developments in this field.
- 41Spano, F. C. The Spectral Signatures of Frenkel Polarons in H- and J-Aggregates. Acc. Chem. Res. 2010, 43 (3), 429– 439, DOI: 10.1021/ar900233vGoogle Scholar44https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsFKgurzL&md5=a66d2effbaf73a403bf00e6e198efe0aThe Spectral Signatures of Frenkel Polarons in H- and J-AggregatesSpano, Frank C.Accounts of Chemical Research (2010), 43 (3), 429-439CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)A review. Electronic excitations in small aggregates, thin films, and crystals of conjugated org. mols. play a fundamental role in the operation of a wide array of org.-based devices including solar cells, transistors, and light-emitting diodes. Such excitations, or excitons, are generally spread out over several mols.: a balance between the delocalizing influence of resonant intermol. coupling and the localizing influence of static and dynamic disorder dets. the coherence range of the exciton. Because of the soft nature of org. materials, significant nuclear relaxation in the participating mols. also accompanies the electronic excitations. To properly understand energy or charge transport, 1 must treat intermol. (excitonic) coupling, electron-vibrational coupling, and disorder on equal footing. In this Account, the authors review the key elements of a theor. approach based on a multiparticle representation that describes electronic excitations in org. materials as vibronic excitations surrounded by a field of vibrational excitations. Such composite excitations are appropriately called Frenkel excitonic polarons. For many conjugated mols., the bulk of the nuclear reorganization energy following electronic excitation arises from the elongation of a sym. vinyl stretching mode with energy ∼1400 cm-1. To appreciate the impact of aggregation, the authors study how the vibronic progression of this mode, which dominates the isolated (solvated) mol. absorption and emission spectra, is distorted when mols. are close enough to interact with each other. As the authors demonstrate in this Account, the nature of the distortion provides a wealth of information about how the mols. are packed, the strength of the excitonic interactions between mols., the no. of mols. that are coherently coupled, and the nature of the disorder. The aggregation-induced deviations from the Poissonian distribution of vibronic peak intensities take on 2 extremes identified with ideal H- and J-aggregates. The sign of the nearest neighbor electronic coupling, pos. for H and neg. for J, distinguishes the 2 basic aggregate forms. For several decades, researchers have known that H-aggregates exhibit blue-shifted absorption spectra and are subradiant while J-aggregates exhibit the opposite behavior (red shifted absorption and superradiance). However, the exact inclusion of exciton-vibrational coupling reveals several more distinguishing traits between the 2 aggregate types: in H(J)-aggregates the ratio of the 1st 2 vibronic peak intensities in the absorption spectrum decreases (increases) with increasing excitonic coupling, while the ratio of the 0-0 to 0-1 emission intensities increases (decreases) with disorder and increases (decreases) with increasing temp. These 2 extreme behaviors provide the framework for understanding absorption and emission in more complex morphologies, such as herringbone packing in oligo(phenylene vinylene)s, oligothiophenes and polyacene crystals, as well as the polymorphic packing arrangements obsd. in carotenoids.
- 42Francis, C.; Fazzi, D.; Grimm, S. B.; Paulus, F.; Beck, S.; Hillebrandt, S.; Pucci, A.; Zaumseil, J. Raman Spectroscopy and Microscopy of Electrochemically and Chemically Doped High-Mobility Semiconducting Polymers. Journal of Materials Chemistry C 2017, 5 (25), 6176– 6184, DOI: 10.1039/C7TC01277BGoogle Scholar45https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXosFSqtLo%253D&md5=530072111b3ddae9109ff463e82166b8Raman spectroscopy and microscopy of electrochemically and chemically doped high-mobility semiconducting polymersFrancis, C.; Fazzi, D.; Grimm, S. B.; Paulus, F.; Beck, S.; Hillebrandt, S.; Pucci, A.; Zaumseil, J.Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2017), 5 (25), 6176-6184CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)The polaronic nature of two high-mobility hole-conducting polymers (PBTTT and DPPT-TT) was studied by Raman spectroscopy and d. functional theory (DFT) calcns. Chem. and electrochem. hole doping of these polymers leads to characteristic changes in the intensity ratios of the Raman active C=C stretching modes but no significant frequency shifts. The data indicate a localization of pos. polarons on the electron-rich thienothiophene cores that are present in both polymers. DFT calcns. show that the Raman intensity ratio variations are most likely caused by the local elec. field that originates from neg. charged dopant mols. or electrolyte anions and the pos. polaron on the polymer chain. The characteristic changes in the Raman mode intensity ratios with the degree of doping enable in situ mapping of charge carrier concn. in the channel of electrolyte-gated polymer transistors with high spatial resoln.
- 43Fei, Z.; Boufflet, P.; Wood, S.; Wade, J.; Moriarty, J.; Gann, E.; Ratcliff, E. L.; McNeill, C. R.; Sirringhaus, H.; Kim, J.-S. Influence of Backbone Fluorination in Regioregular Poly(3-Alkyl-4-Fluoro)Thiophenes. J. Am. Chem. Soc. 2015, 137 (21), 6866– 6879, DOI: 10.1021/jacs.5b02785Google Scholar46https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXovVShtbw%253D&md5=02a47d4e12034011b943d1fb4aa7f315Influence of Backbone Fluorination in Regioregular Poly(3-alkyl-4-fluoro)thiophenesFei, Zhuping; Boufflet, Pierre; Wood, Sebastian; Wade, Jessica; Moriarty, John; Gann, Eliot; Ratcliff, Erin L.; McNeill, Christopher R.; Sirringhaus, Henning; Kim, Ji-Seon; Heeney, MartinJournal of the American Chemical Society (2015), 137 (21), 6866-6879CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)We report two strategies toward the synthesis of 3-alkyl-4-fluorothiophenes contg. straight (hexyl and octyl) and branched (2-ethylhexyl) alkyl groups. We demonstrate that treatment of the dibrominated monomer with 1 equiv of alkyl Grignard reagent leads to the formation of a single regioisomer as a result of the pronounced directing effect of the fluorine group. Polymn. of the resulting species affords highly regioregular poly(3-alkyl-4-fluoro)thiophenes. Comparison of their properties to those of the analogous non-fluorinated polymers shows that backbone fluorination leads to an increase in the polymer ionization potential without a significant change in optical band gap. Fluorination also results in an enhanced tendency to aggregate in soln., which is ascribed to a more co-planar backbone on the basis of Raman and DFT calcns. Av. charge carrier mobilities in field-effect transistors are found to increase by up to a factor of 5 for the fluorinated polymers.
- 44Wood, S.; Hollis, J. R.; Kim, J.-S. Raman Spectroscopy as an Advanced Structural Nanoprobe for Conjugated Molecular Semiconductors. J. Phys. D: Appl. Phys. 2017, 50 (7), 073001, DOI: 10.1088/1361-6463/50/7/073001Google Scholar47https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXptFKrtbw%253D&md5=c0f6607175929bcbfdd444504e64e49bRaman spectroscopy as an advanced structural nanoprobe for conjugated molecular semiconductorsWood, Sebastian; Hollis, Joseph Razzell; Kim, Ji-SeonJournal of Physics D: Applied Physics (2017), 50 (7), 073001/1-073001/32CODEN: JPAPBE; ISSN:0022-3727. (IOP Publishing Ltd.)A review. Raman spectroscopy has emerged as a powerful and important characterization tool for probing mol. semiconducting materials. The useful optoelectronic properties of these materials arise from the delocalised π-electron d. in the conjugated core of the mol., which also results in large Raman scattering cross-sections and a strong coupling between its electronic states and vibrational modes. For this reason, Raman spectroscopy offers a unique insight into the properties of mol. semiconductors, including: chem. structure, mol. conformation, mol. orientation, and fundamental photo- and electro-chem. processes-all of which are critically important to the performance of a wide range of optical and electronic org. semiconductor devices. Exptl., Raman spectroscopy is nonintrusive, non-destructive, and requires no special sample prepn., and so is suitable for a wide range of in situ measurements, which are particularly relevant to issues of thermal and photochem. stability. Here we review the development of the family of Raman spectroscopic techniques, which have been applied to the study of conjugated mol. semiconductors. We consider the suitability of each technique for particular circumstances, and the unique insights it can offer, with a particular focus on the significance of these measurements for the continuing development of stable, high performance org. electronic devices.
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- 1Dai, Y.; Hu, H.; Wang, M.; Xu, J.; Wang, S. Stretchable Transistors and Functional Circuits for Human-Integrated Electronics. Nat. Electron 2021, 4 (1), 17– 29, DOI: 10.1038/s41928-020-00513-51https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhtVGrs70%253D&md5=b502c73ddcfae36f940d567d0c433cd9Stretchable transistors and functional circuits for human-integrated electronicsDai, Yahao; Hu, Huawei; Wang, Maritha; Xu, Jie; Wang, SihongNature Electronics (2021), 4 (1), 17-29CODEN: NEALB3; ISSN:2520-1131. (Nature Research)A review. Abstr.: Electronics with skin- or tissue-like mech. properties, including low stiffness and high stretchability, can be used to create intelligent technologies for application in areas such as health monitoring and human-machine interactions. Stretchable transistors that provide signal-processing and computational functions will be central to the development of this technol. Here, we review the development of stretchable transistors and functional circuits, examg. progress in terms of materials and device engineering. We consider the three established approaches for creating stretchable transistors: buckling engineering, stiffness engineering and intrinsic-stretchability engineering. We also explore the current capabilities of stretchable transistors and circuits in human-integrated electronics and consider the challenges involved in delivering advanced applications.
- 2Li, G.; Chang, W.-H.; Yang, Y. Low-Bandgap Conjugated Polymers Enabling Solution-Processable Tandem Solar Cells. Nat. Rev. Mater. 2017, 2 (8), 17043, DOI: 10.1038/natrevmats.2017.432https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXht1eksLbM&md5=314924c901ae11a481a13b9c128806d0Low-bandgap conjugated polymers enabling solution-processable tandem solar cellsLi, Gang; Chang, Wei-Hsuan; Yang, YangNature Reviews Materials (2017), 2 (8), 17043CODEN: NRMADL; ISSN:2058-8437. (Nature Publishing Group)The technol. of polymer-based org. photovoltaic (OPV) cells has made great progress in the past decade, with the power conversion efficiency increasing from just a few per cent to around 12%, and the stability increasing from hours to years. One of the important milestones in this progress has been the invention of IR-absorbing low-bandgap polymers, which allows the OPV cells to form effective tandem structures for harvesting near-IR energy from the solar spectrum. In this Review, we focus on the progress in low-bandgap conjugated polymers and several tandem OPV cells enabled by these low-bandgap polymers. Specifically, we cover polymer-based tandem solar cells; hybrid tandem solar cells combining polymers with hydrogenated amorphous silicon; and unconventional solar cells. For each of these technologies, we address the challenges and offer our perspectives for future development.
- 3Russ, B.; Glaudell, A.; Urban, J. J.; Chabinyc, M. L.; Segalman, R. A. Organic Thermoelectric Materials for Energy Harvesting and Temperature Control. Nat. Rev. Mater. 2016, 1 (10), 16050, DOI: 10.1038/natrevmats.2016.503https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtVertLg%253D&md5=cd6c25346273d09b1b6cb2ba6616f7b5Organic thermoelectric materials for energy harvesting and temperature controlRuss, Boris; Glaudell, Anne; Urban, Jeffrey J.; Chabinyc, Michael L.; Segalman, Rachel A.Nature Reviews Materials (2016), 1 (10), 16050CODEN: NRMADL; ISSN:2058-8437. (Nature Publishing Group)Conjugated polymers and related processing techniques have been developed for org. electronic devices ranging from lightwt. photovoltaics to flexible displays. These breakthroughs have recently been used to create org. thermoelec. materials, which have potential for wearable heating and cooling devices, and near-room-temp. energy generation. So far, the best thermoelec. materials have been inorg. compds. (such as Bi2Te3) that have relatively low Earth abundance and are fabricated through highly complex vacuum processing routes. Mol. materials and hybrid org.-inorg. materials now demonstrate figures of merit approaching those of these inorg. materials, while also exhibiting unique transport behaviors that are suggestive of optimization pathways and device geometries that were not previously possible. In this Review, we discuss recent breakthroughs for org. materials with high thermoelec. figures of merit and indicate how these materials may be incorporated into new module designs that take advantage of their mech. and thermoelec. properties.
- 4MacFarlane, L. R.; Shaikh, H.; Garcia-Hernandez, J. D.; Vespa, M.; Fukui, T.; Manners, I. Functional Nanoparticles through π-Conjugated Polymer Self-Assembly. Nat. Rev. Mater. 2021, 6 (1), 7– 26, DOI: 10.1038/s41578-020-00233-44https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXitlWks7fN&md5=78616dc7d72567394b5796adbb0e2cdbFunctional nanoparticles through π-conjugated polymer self-assemblyMacFarlane, Liam R.; Shaikh, Huda; Garcia-Hernandez, J. Diego; Vespa, Marcus; Fukui, Tomoya; Manners, IanNature Reviews Materials (2021), 6 (1), 7-26CODEN: NRMADL; ISSN:2058-8437. (Nature Research)A review. The development of π-conjugated polymers has provided a gateway to a variety of new functional org. materials reminiscent of inorg. semiconductors. Nanoparticles based on π-conjugated polymers are promising for a broad range of emerging applications. In this Review, we provide an overview of the methods used to synthesize π-conjugated-polymer nanoparticles, with a focus on recently developed self-assembly and microfluidic routes. We also illustrate the use of the resulting nanoparticles in applications such as electronics and optoelectronics, biomedical imaging and therapy, photocatalysis and sensing. Finally, we discuss current challenges and possible directions for future research on this promising class of nanomaterials.
- 5Muench, S.; Wild, A.; Friebe, C.; Häupler, B.; Janoschka, T.; Schubert, U. S. Polymer-Based Organic Batteries. Chem. Rev. 2016, 116 (16), 9438– 9484, DOI: 10.1021/acs.chemrev.6b000705https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xht1Ggtr7J&md5=46d082a2643ad0c4b2828e08bd4fcdbePolymer-Based Organic BatteriesMuench, Simon; Wild, Andreas; Friebe, Christian; Haeupler, Bernhard; Janoschka, Tobias; Schubert, Ulrich S.Chemical Reviews (Washington, DC, United States) (2016), 116 (16), 9438-9484CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)The storage of elec. energy is of ever growing importance for our modern, technol.-based society, and novel battery systems are in the focus of research. The substitution of conventional metals as redox-active material by org. materials offers a promising alternative for the next generation of rechargeable batteries since these org. batteries are excelling in charging speed and cycling stability. This review provides a comprehensive overview of these systems and discusses the numerous classes of org., polymer-based active materials as well as auxiliary components of the battery, like additives or electrolytes. Moreover, a definition of important cell characteristics and an introduction to selected characterization techniques is provided, completed by the discussion of potential socio-economic impacts.
- 6Liu, Y.; Feig, V. R.; Bao, Z. Conjugated Polymer for Implantable Electronics toward Clinical Application. Adv. Healthcare Mater. 2021, 10 (17), 2001916, DOI: 10.1002/adhm.2020019166https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXpsVSrsL8%253D&md5=b462b61bb0bd61ad170254cf44c6ce7fConjugated Polymer for Implantable Electronics toward Clinical ApplicationLiu, Yuxin; Feig, Vivian Rachel; Bao, ZhenanAdvanced Healthcare Materials (2021), 10 (17), 2001916CODEN: AHMDBJ; ISSN:2192-2640. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Owing to their excellent mech. flexibility, mixed-conducting elec. property, and extraordinary chem. turnability, conjugated polymers have been demonstrated to be an ideal bioelectronic interface to deliver therapeutic effect in many different chronic diseases. This review article summarizes the latest advances in implantable electronics using conjugated polymers as electroactive materials and identifies remaining challenges and opportunities for developing electronic medicine. Examples of conjugated polymer-based bioelectronic devices are selectively reviewed in human clin. studies or animal studies with the potential for clin. adoption. The unique properties of conjugated polymers are highlighted and exemplified as potential solns. to address the specific challenges in electronic medicine.
- 7Park, K. S.; Kwok, J. J.; Kafle, P.; Diao, Y. When Assembly Meets Processing: Tuning Multiscale Morphology of Printed Conjugated Polymers for Controlled Charge Transport. Chem. Mater. 2021, 33 (2), 469– 498, DOI: 10.1021/acs.chemmater.0c041527https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXpvFyltg%253D%253D&md5=ba70201aa28d29d593cc3c6355c788d2When Assembly Meets Processing: Tuning Multiscale Morphology of Printed Conjugated Polymers for Controlled Charge TransportPark, Kyung Sun; Kwok, Justin J.; Kafle, Prapti; Diao, YingChemistry of Materials (2021), 33 (2), 469-498CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)A review. Conjugated polymers are rapidly emerging as an attractive class of semiconductors for next-generation electronics thanks to their low-cost, high-throughput soln. processability, mech. flexibility, stretchability, self-healing properties, and their ability to interface and communicate with biol. systems. Accordingly, the last four decades has seen a surge of studies that have provided seminal contributions to the thorough understanding of conjugated polymers. One of the key factors that dictates the electronic performance of conjugated polymers is their assembly and crystn. behavior, which has remained intriguing and challenging to study. The complex soln. processing environment and rapid kinetics strongly couple with the conjugated polymer assembly process, further complicating a full mechanistic picture. In this perspective, we summarize the charge transport mechanism, fundamentals of conjugated polymer assembly and soln. printing. We further discuss central strategies that have been developed to control and enhance their multiscale assembly during soln. printing. Finally, we hope that our perspective will stimulate more studies on how processing can control morphol. and charge transport of conjugated polymers and applications of these concepts to other advanced functional materials.
- 8Swager, T. M. 50th Anniversary Perspective: Conducting/Semiconducting Conjugated Polymers. A Personal Perspective on the Past and the Future. Macromolecules 2017, 50 (13), 4867– 4886, DOI: 10.1021/acs.macromol.7b005828https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXps1CjsLY%253D&md5=cdc859cf4b9262b65a97d32cbf5639a950th Anniversary Perspective: Conducting/Semiconducting Conjugated Polymers. A Personal Perspective on the Past and the FutureSwager, Timothy M.Macromolecules (Washington, DC, United States) (2017), 50 (13), 4867-4886CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)A review. It has been about 40 years since the field of org. conducting polymers was ignited by the demonstration of metallic cond. in polyacetylene. A retrospective view of this research area suggests some areas remain ripe for discovery/innovation. The breadth of activities is too large to be comprehensive; hence, selected seminal, as well as some personal, contributions will be used to illustrate concepts and anecdotal ways to think about conducting polymer systems. This Perspective can serve as a tutorial for newcomers to the field and will also remind experts about results from the past. It begins with some history and simple views of electronic structure, with selected examples. Segmented polymers contg. isolated redox units will be discussed as well as how these materials can be made to have high cond. Key examples illustrating the matching of redox potentials are transition metal hybrid structures. Interchain interactions are emphasized along with their role in detg. the nature of the charges. Recent results that demonstrate dramatic magneto-optical properties wherein the transmission of polarized light through conjugated polymers displays dramatic sensitivity to applied magnetic fields (Faraday effect) will also be discussed.
- 9Mei, J.; Bao, Z. Side Chain Engineering in Solution-Processable Conjugated Polymers. Chem. Mater. 2014, 26 (1), 604– 615, DOI: 10.1021/cm40208059https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtlChtrjF&md5=a32573f25773f9428beb41b5c8cfd497Side Chain Engineering in Solution-Processable Conjugated PolymersMei, Jianguo; Bao, ZhenanChemistry of Materials (2014), 26 (1), 604-615CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)A review. Side chains in conjugated polymers were primarily utilized as solubilizing groups. However, these side chains have roles that are far beyond. We advocate using side chain engineering to tune a polymer's phys. properties, including absorption, emission, energy level, mol. packing, and charge transport. To date, numerous flexible substituents suitable for constructing side chains have been reported. In this Perspective article, we advocate that the side chain engineering approach can advance better designs for next-generation conjugated polymers.
- 10Yao, Z.-F.; Wang, J.-Y.; Pei, J. Controlling Morphology and Microstructure of Conjugated Polymers via Solution-State Aggregation. Prog. Polym. Sci. 2023, 136, 101626, DOI: 10.1016/j.progpolymsci.2022.10162610https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XivFOmtbzN&md5=ab46d845e356815e661fef061d0ec3c9Controlling morphology and microstructure of conjugated polymers via solution-state aggregationYao, Ze-Fan; Wang, Jie-Yu; Pei, JianProgress in Polymer Science (2023), 136 (), 101626CODEN: PRPSB8; ISSN:0079-6700. (Elsevier Ltd.)The macroscopic functions and properties of conjugated polymers depend on their microcosmic morphol. and microstructure in the solid state. However, such morphol. and microstructure from mols. to solid states are complicated. Therefore, it is a significant challenge to reveal the relationship among mol. structures to the complex microstructure and finally to device functions. This review focuses on the formation, behavior, and evolution of soln.-state aggregation of conjugated polymers, which can influence and even det. the solid-state morphol. and microstructure, ultimately clarifying the relationship between the microstructure and the properties of conjugated polymers. The crit. role of soln.-state aggregation is highlighted from a theor. understanding of mol. interactions between polymer chains (conjugated backbones and/or flexible side chains) and solvent mols. We highlight the recent progress on high-performance polymer-based devices through the soln.-state aggregation strategy. Furthermore, we summarize the challenges and essential research direction on the soln.-state aggregation, which will be addressed and established in the future. Therefore, an in-depth understanding of polymer aggregation will advance the development of high-performance conjugated polymers in various functional devices.
- 11Matsidik, R.; Luzio, A.; Askin, Ö.; Fazzi, D.; Sepe, A.; Steiner, U.; Komber, H.; Caironi, M.; Sommer, M. Highly Planarized Naphthalene Diimide-Bifuran Copolymers with Unexpected Charge Transport Performance. Chem. Mater. 2017, 29 (13), 5473– 5483, DOI: 10.1021/acs.chemmater.6b0531311https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXpslCkurg%253D&md5=3e66130b3d463d2c4fb02ac57f35ad03Highly Planarized Naphthalene Diimide-Bifuran Copolymers with Unexpected Charge Transport PerformanceMatsidik, Rukiya; Luzio, Alessandro; Askin, Oezge; Fazzi, Daniele; Sepe, Alessandro; Steiner, Ullrich; Komber, Hartmut; Caironi, Mario; Sommer, MichaelChemistry of Materials (2017), 29 (13), 5473-5483CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)The synthesis, characterization, and charge transport performance of novel copolymers PNDIFu2 made from alternating naphthalene diimide (NDI) and bifuran (Fu2) units are reported. Usage of potentially biomass-derived Fu2 as alternating repeat unit enables flattened polymer backbones due to reduced steric interactions between the imide oxygens and Fu2 units, as seen by d. functional theory (DFT) calcns. and UV-vis spectroscopy. Aggregation of PNDIFu2 in soln. is enhanced if compared to the analogous NDI-bithiophene (T2) copolymers PNDIT2, occurring in all solvents and temps. probed. PNDIFu2 features a smaller π-π stacking distance of 0.35 nm compared to 0.39 nm seen for PNDIT2. Alignment of aggregates in films is achieved by using off-center spin coating, whereby PNDIFu2 exhibits a stronger dichroic ratio and transport anisotropy in field-effect transistors (FET) compared to PNDIT2, with an overall good electron mobility of 0.21 cm2/(V s). Despite an enhanced backbone planarity, the smaller π-π stacking and the enhanced charge transport anisotropy, the electron mobility of PNDIFu2 is about three times lower compared to PNDIT2. D. functional theory calcns. suggest that charge transport in PNDIFu2 is limited by enhanced polaron localization compared to PNDIT2.
- 12Gross, Y. M.; Trefz, D.; Tkachov, R.; Untilova, V.; Brinkmann, M.; Schulz, G. L.; Ludwigs, S. Tuning Aggregation by Regioregularity for High-Performance n-Type P(NDI2OD-T 2) Donor-Acceptor Copolymers. Macromolecules 2017, 50 (14), 5353– 5366, DOI: 10.1021/acs.macromol.7b0138612https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFKmurvN&md5=46d4b879147b16d06f7c7452be94f8b6Tuning Aggregation by Regioregularity for High-Performance n-Type P(NDI2OD-T2) Donor-Acceptor CopolymersGross, Yannic M.; Trefz, Daniel; Tkachov, Roman; Untilova, Viktoriia; Brinkmann, Martin; Schulz, Gisela L.; Ludwigs, SabineMacromolecules (Washington, DC, United States) (2017), 50 (14), 5353-5366CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)We report on the controlled synthesis of naphthalenediimide-bithiophene copolymers with varying ratios of 2,6- and 2,7-linkage (parent polymer: poly{[N,N'-bis(2-octyldodecyl)-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} P(NDI2OD-T2)). Monomers with different ratios of 2,6- and 2,7-regioisomers could be isolated, leading to n-type polymers with tunable regioregularity. With increasing content of 2,7-linkage in the polymer backbone the aggregation tendency can be drastically reduced. Both the redn. behavior and the electron transport properties are very similar for all systems. For the regioregular system we find mobility values of 3 × 10-1 cm2/(V s); the regioirregular systems become comparable with values as high as 7 × 10-2 cm2/(V s) when temp. annealing is employed. This means that regioregularity seems to have an overall lower effect in comparison to classical systems such as poly(3-hexylthiophene). Tuning regioregularity in such systems therefore provides a powerful tool to optimize processing without deteriorating device performance. We even find that device performance of bulk-heterojunction solar cells with a polythiophene deriv. as donor strongly improves upon use of the regioirregular systems.
- 13Chen, M. S.; Lee, O. P.; Niskala, J. R.; Yiu, A. T.; Tassone, C. J.; Schmidt, K.; Beaujuge, P. M.; Onishi, S. S.; Toney, M. F.; Zettl, A. Enhanced Solid-State Order and Field-Effect Hole Mobility through Control of Nanoscale Polymer Aggregation. J. Am. Chem. Soc. 2013, 135 (51), 19229– 19236, DOI: 10.1021/ja408866513https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhvFSlt7vK&md5=527eff5dc584b4dd812950f12ff55500Enhanced Solid-State Order and Field-Effect Hole Mobility through Control of Nanoscale Polymer AggregationChen, Mark S.; Lee, Olivia P.; Niskala, Jeremy R.; Yiu, Alan T.; Tassone, Christopher J.; Schmidt, Kristin; Beaujuge, Pierre M.; Onishi, Seita S.; Toney, Michael F.; Zettl, Alex; Frechet, Jean M. J.Journal of the American Chemical Society (2013), 135 (51), 19229-19236CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Efficient charge carrier transport in org. field-effect transistors (OFETs) often requires thin films that display long-range order and close π-π packing that is oriented in-plane with the substrate. Although some polymers have achieved high field-effect mobility with such solid-state properties, there are currently few general strategies for controlling the orientation of π-stacking within polymer films. In order to probe structural effects on polymer-packing alignment, furan-contg. diketopyrrolopyrrole (DPP) polymers with similar optoelectronic properties were synthesized with either linear hexadecyl or branched 2-butyloctyl side chains. Differences in polymer soly. were obsd. and attributed to variation in side-chain shape and polymer backbone curvature. Averaged field-effect hole mobilities of the polymers range from 0.19 to 1.82 cm2/V·s, where PDPP3F-C16 is the least sol. polymer and provides the highest max. mobility of 2.25 cm2/V·s. Anal. of the films by AFM and GIXD reveal that less sol. polymers with linear side chains exhibit larger cryst. domains, pack considerably more closely, and align with a greater preference for in-plane π-π packing. Characterization of the polymer solns. prior to spin-coating shows a correlation between early onset nanoscale aggregation and the formation of films with highly oriented in-plane π-stacking. This effect is further obsd. when nonsolvent is added to PDPP3F-BO solns. to induce aggregation, which results in films with increased nanostructural order, in-plane π-π orientation, and field-effect hole mobilities. Since nearly all π-conjugated materials may be coaxed to aggregate, this strategy for enhancing solid-state properties and OFET performance has applicability to a wide variety of org. electronic materials.
- 14Xu, Z.; Park, K. S.; Kwok, J. J.; Lin, O.; Patel, B. B.; Kafle, P.; Davies, D. W.; Chen, Q.; Diao, Y. Not All Aggregates Are Made the Same: Distinct Structures of Solution Aggregates Drastically Modulate Assembly Pathways, Morphology, and Electronic Properties of Conjugated Polymers. Adv. Mater. 2022, 34 (32), 2203055, DOI: 10.1002/adma.20220305514https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhvVChtL%252FJ&md5=a83e215be9abb6c52a02263c15158fcbNot All Aggregates Are Made the Same: Distinct Structures of Solution Aggregates Drastically Modulate Assembly Pathways, Morphology, and Electronic Properties of Conjugated PolymersXu, Zhuang; Park, Kyung Sun; Kwok, Justin J.; Lin, Oliver; Patel, Bijal B.; Kafle, Prapti; Davies, Daniel W.; Chen, Qian; Diao, YingAdvanced Materials (Weinheim, Germany) (2022), 34 (32), 2203055CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)Tuning structures of soln.-state aggregation and aggregation-mediated assembly pathways of conjugated polymers is crucial for optimizing their solid-state morphol. and charge-transport property. However, it remains challenging to unravel and control the exact structures of soln. aggregates, let alone to modulate assembly pathways in a controlled fashion. Herein, aggregate structures of an isoindigo-bithiophene-based polymer (PII-2T) are modulated by tuning selectivity of the solvent toward the side chain vs. the backbone, which leads to 3 distinct assembly pathways: direct crystn. from side-chain-assocd. amorphous aggregates, chiral liq. crystal (LC)-mediated assembly from semicryst. aggregates with side-chain and backbone stacking, and random agglomeration from backbone-stacked semicryst. aggregates. Importantly, the amorphous soln. aggregates, compared with semicryst. ones, lead to significantly improved alignment and reduced paracryst. disorder in the solid state due to direct crystn. during the meniscus-guided coating process. Alignment quantified by the dichroic ratio is enhanced by up to 14-fold, and the charge-carrier mobility increases by a max. of 20-fold in films printed from amorphous aggregates compared to those from semicryst. aggregates. By tuning the precise structure of soln. aggregates, the assembly pathways and the resulting thin-film morphol. and device properties can be drastically tuned.
- 15Panzer, F.; Bässler, H.; Köhler, A. Temperature Induced Order-Disorder Transition in Solutions of Conjugated Polymers Probed by Optical Spectroscopy. J. Phys. Chem. Lett. 2017, 8 (1), 114– 125, DOI: 10.1021/acs.jpclett.6b0164115https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitVGntrrO&md5=dea8b0ced6f7350d98aeb1356cfbbbdeTemperature Induced Order-Disorder Transition in Solutions of Conjugated Polymers Probed by Optical SpectroscopyPanzer, Fabian; Baessler, Heinz; Koehler, AnnaJournal of Physical Chemistry Letters (2017), 8 (1), 114-125CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)The aggregation of π-conjugated materials significantly impacts the photophysics and performance of optoelectronic devices. Nevertheless, little is known about the laws governing aggregate formation of π-conjugated materials from soln. In this Perspective, we compare, discuss, and summarize how aggregates form for three different types of compds., i.e., homopolymers, donor-acceptor type polymers, and low mol. wt. compds. To this end, we employ temp.-dependent optical spectroscopy, which is a simple yet powerful tool to study aggregate formation. We show how optical spectra can be analyzed to identify distinct conformational states. We find aggregate formation to proceed the same in all these compds. by a coil-to-globule-like first-order phase transition. Notably, the chain expands before it collapses into a highly ordered dense state. The role of side chains and the impact of changes in environmental polarization are addressed.
- 16Park, Y. D.; Lee, S. G.; Lee, H. S.; Kwak, D.; Lee, D. H.; Cho, K. Solubility-Driven Polythiophene Nanowires and Their Electrical Characteristics. J. Mater. Chem. 2011, 21 (7), 2338– 2343, DOI: 10.1039/C0JM03114C16https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtlOisrY%253D&md5=bd2f51c65205f5fe0785ba79cb2041deSolubility-driven polythiophene nanowires and their electrical characteristicsPark, Yeong Don; Lee, Seung Goo; Lee, Hwa Sung; Kwak, Donghoon; Lee, Dae Ho; Cho, KilwonJournal of Materials Chemistry (2011), 21 (7), 2338-2343CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)We demonstrated that interconnected nanofibrillar networks of poly(3-hexylthiophene) (P3HT) thin films with improved crystallinity can be easily fabricated by aging the precursor soln. with marginal solvent. Structural anal. revealed that these benefits arise from the improvements in the crystallinity of P3HT in the precursor soln. At dil. concns., P3HT mols. grew into near-spherical particles during the aging time. As the aging time increased further, P3HT mols. exhibited one-dimensional growth into rod-like structures. At higher P3HT concns. and longer P3HT soln. aging times, dense nanowires were obsd. to form gradually, thereby improving the electronic properties of field-effect transistors (FETs) based on these films. This improvement was due to the change in P3HT organization in the precursor soln. from a random-coil conformation to an ordered aggregate as a result of aging in a marginal solvent, methylene chloride. At high temps., the P3HT mols. were completely solvated and adopted a random-coil conformation, as is obsd. in good solvents. Whereas upon aging the soln. at room temp., methylene chloride poorly solvated the P3HT mols. such that ordered aggregates of P3HT grew in soln., which improved the mol. ordering of P3HT thin films produced from these solns. The field-effect mobility of the thin films was, therefore, enhanced without the need for post-treatments.
- 17Li, M.; Balawi, A. H.; Leenaers, P. J.; Ning, L.; Heintges, G. H. L.; Marszalek, T.; Pisula, W.; Wienk, M. M.; Meskers, S. C. J.; Yi, Y. Impact of Polymorphism on the Optoelectronic Properties of a Low-Bandgap Semiconducting Polymer. Nat. Commun. 2019, 10 (1), 2867, DOI: 10.1038/s41467-019-10519-z17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB3MzitF2iuw%253D%253D&md5=769991caf94fba939b15c19387dc0668Impact of polymorphism on the optoelectronic properties of a low-bandgap semiconducting polymerLi Mengmeng; Leenaers Pieter J; Heintges Gael H L; Wienk Martijn M; Meskers Stefan C J; Janssen Rene A J; Li Mengmeng; Janssen Rene A J; Balawi Ahmed Hesham; Laquai Frederic; Ning Lu; Yi Yuanping; Heintges Gael H L; Marszalek Tomasz; Pisula Wojciech; Marszalek Tomasz; Pisula WojciechNature communications (2019), 10 (1), 2867 ISSN:.Polymorphism of organic semiconducting materials exerts critical effects on their physical properties such as optical absorption, emission and electrical conductivity, and provides an excellent platform for investigating structure-property relations. It is, however, challenging to efficiently tune the polymorphism of conjugated polymers in aggregated, semi-crystalline phases due to their conformational freedom and anisotropic nature. Here, two distinctly different semi-crystalline polymorphs (β1 and β2) of a low-bandgap diketopyrrolopyrrole polymer are formed through controlling the solvent quality, as evidenced by spectroscopic, structural, thermal and charge transport studies. Compared to β1, the β2 polymorph exhibits a lower optical band gap, an enhanced photoluminescence, a reduced π-stacking distance, a higher hole mobility in field-effect transistors and improved photocurrent generation in polymer solar cells. The β1 and β2 polymorphs provide insights into the control of polymer self-organization for plastic electronics and hold potential for developing programmable ink formulations for next-generation electronic devices.
- 18Park, K. S.; Xue, Z.; Patel, B. B.; An, H.; Kwok, J. J.; Kafle, P.; Chen, Q.; Shukla, D.; Diao, Y. Chiral Emergence in Multistep Hierarchical Assembly of Achiral Conjugated Polymers. Nat. Commun. 2022, 13 (1), 2738, DOI: 10.1038/s41467-022-30420-618https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xhtlajt73O&md5=bd089ed160718bf9208f2e605d34db7dChiral emergence in multistep hierarchical assembly of achiral conjugated polymersPark, Kyung Sun; Xue, Zhengyuan; Patel, Bijal B.; An, Hyosung; Kwok, Justin J.; Kafle, Prapti; Chen, Qian; Shukla, Diwakar; Diao, YingNature Communications (2022), 13 (1), 2738CODEN: NCAOBW; ISSN:2041-1723. (Nature Portfolio)Intimately connected to the rule of life, chirality remains a long-time fascination in biol., chem., physics and materials science. Chiral structures, e.g., nucleic acid and cholesteric phase developed from chiral mols. are common in nature and synthetic soft materials. While it was recently discovered that achiral but bent-core mesogens can also form chiral helixes, the assembly of chiral microstructures from achiral polymers has rarely been explored. Here, we reveal chiral emergence from achiral conjugated polymers, in which hierarchical helical structures are developed through a multistep assembly pathway. Upon increasing concn. beyond a threshold vol. fraction, dispersed polymer nanofibers form lyotropic liq. cryst. (LC) mesophases with complex, chiral morphologies. Combining imaging, X-ray and spectroscopy techniques with mol. simulations, we demonstrate that this structural evolution arises from torsional polymer mols. which induce multiscale helical assembly, progressing from nano- to micron scale helical structures as the soln. concn. increases. This study unveils a previously unknown complex state of matter for conjugated polymers that can pave way to a field of chiral (opto)electronics. We anticipate that hierarchical chiral helical structures can profoundly impact how conjugated polymers interact with light, transport charges, and transduce signals from biomol. interactions and even give rise to properties unimagined before.
- 19Ariga, K.; Mori, T.; Kitao, T.; Uemura, T. Supramolecular Chiral Nanoarchitectonics. Adv. Mater. 2020, 32 (41), 1905657, DOI: 10.1002/adma.20190565719https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXltlers7g%253D&md5=29477ad508aa1f1c71c338359e417912Supramolecular Chiral NanoarchitectonicsAriga, Katsuhiko; Mori, Taizo; Kitao, Takashi; Uemura, TakashiAdvanced Materials (Weinheim, Germany) (2020), 32 (41), 1905657CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Exploration of mol. functions and material properties based on the control of chirality would be a scientifically elegant approach. Here, the fabrication and function of chiral-featured materials from both chiral and achiral components using a supramol. nanoarchitectonics concept are discussed. The contents are classified in to three topics: (i) chiral nanoarchitectonics of rather general mol. assemblies; (ii) chiral nanoarchitectonics of metal-org. frameworks (MOFs); (iii) chiral nanoarchitectonics in liq. crystals. MOF structures are based on nanoscopically well-defined coordinations, while mesoscopic orientations of liq.-cryst. phases are often flexibly altered. Discussion on the effects and features in these representative materials systems with totally different natures reveals the universal importance of supramol. chiral nanoarchitectonics. Amplification of chiral mol. information from mols. to materials-level structures and the creation of chirality from achiral components upon temporal statistic fluctuations are universal, regardless of the nature of the assemblies. These features are thus surely advantageous characteristics for a wide range of applications.
- 20Brandt, J. R.; Salerno, F.; Fuchter, M. J. The Added Value of Small-Molecule Chirality in Technological Applications. Nat. Rev. Chem. 2017, 1 (6), 0045, DOI: 10.1038/s41570-017-004520https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtVyksb7K&md5=540f1e144f678b544fcd1d14d97dbeedThe added value of small-molecule chirality in technological applicationsBrandt, Jochen R.; Salerno, Francesco; Fuchter, Matthew J.Nature Reviews Chemistry (2017), 1 (6), 0045CODEN: NRCAF7; ISSN:2397-3358. (Nature Research)A review. Chirality is a fundamental symmetry property; chiral objects, such as chiral small mols., exist as a pair of non-superimposable mirror images. Although small-mol. chirality is routinely considered in biol. focused application areas (such as drug discovery and chem. biol.), other areas of scientific development have not considered small-mol. chirality to be central to their approach. In this Review, we highlight recent research in which chirality has enabled advancement in technol. applications. We showcase examples in which the presence of small-mol. chirality is exploited in ways beyond the simple interaction of two different chiral mols.; this can enable the detection and emission of chiral light, help to control mol. motion, or provide a means to control electron spin and bulk charge transport. Thus, we demonstrate that small-mol. chirality is a highly promising avenue for a wide range of technol. oriented scientific endeavours.
- 21Song, I.; Ahn, J.; Ahn, H.; Lee, S. H.; Mei, J.; Kotov, N. A.; Oh, J. H. Helical Polymers for Dissymmetric Circularly Polarized Light Imaging. Nature 2023, 617 (7959), 92– 99, DOI: 10.1038/s41586-023-05877-021https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3sXpt1ejt7w%253D&md5=8f02c49aa36b0125b5829e4dc36c1ff9Helical polymers for dissymmetric circularly polarized light imagingSong, Inho; Ahn, Jaeyong; Ahn, Hyungju; Lee, Sang Hyuk; Mei, Jianguo; Kotov, Nicholas A.; Oh, Joon HakNature (London, United Kingdom) (2023), 617 (7959), 92-99CODEN: NATUAS; ISSN:1476-4687. (Nature Portfolio)Control of the spin angular momentum (SAM) carried in a photon provides a technol. attractive element for next-generation quantum networks and spintronics1-5. However, the weak optical activity and inhomogeneity of thin films from chiral mol. crystals result in high noise and uncertainty in SAM detection. Brittleness of thin mol. crystals represents a further problem for device integration and practical realization of chiroptical quantum devices6-10. Despite considerable successes with highly dissym. optical materials based on chiral nanostructures11-13, the problem of integration of nanochiral materials with optical device platforms remains acute14-16. Here we report a simple yet powerful method to fabricate chiroptical flexible layers via supramol. helical ordering of conjugated polymer chains. Their multiscale chirality and optical activity can be varied across the broad spectral range by chiral templating with volatile enantiomers. After template removal, chromophores remain stacked in one-dimensional helical nanofibrils producing a homogeneous chiroptical layer with drastically enhanced polarization-dependent absorbance, leading to well-resolved detection and visualization of SAM. This study provides a direct path to scalable realization of on-chip detection of the spin degree of freedom of photons necessary for encoded quantum information processing and high-resoln. polarization imaging.
- 22Jiang, S.; Kotov, N. A. Circular Polarized Light Emission in Chiral Inorganic Nanomaterials. Adv. Mater. 2023, 35, 2108431, DOI: 10.1002/adma.20210843122https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XlvVentLY%253D&md5=657482e4b4e6caf2a3e372b371de2738Review on circular polarized light emission in chiral inorganic nanomaterialsJiang, Shuang; Kotov, Nicholas A.Advanced Materials (Weinheim, Germany) (2023), 35 (34), 2108431CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Chiral inorg. nanostructures strongly interact with photons changing their polarization state. The resulting circularly polarized light emission (CPLE) has cross-disciplinary importance for a variety of chem./biol. processes and is essential for development of chiral photonics. However, the polarization effects are often complex and their interpretation is dependent on the several structural parameters of the chiral nanostructure. CPLE in nanostructured media has multiple origins and several optical effects are typically convoluted into a single output. Analyzing CPLE data obtained for nanoclusters, nanoparticles, nanoassemblies, and nanocomposites from metals, chalcogenides, perovskite, and other nanostructures, it is shown here that there are several distinct groups of nanomaterials for which CPLE is dominated either by circularly polarized luminescence (CPL) or circularly polarized scattering (CPS); there are also many nanomaterials for which they are comparable. The following points are also demonstrated: (1) CPL and CPS contributions involve light-matter interactions at different structural levels; (2) contribution from CPS is esp. strong for nanostructured microparticles, nanoassemblies, and composites; and (3) engineering of materials with strongly polarized light emission requires synergistic implementation of CPL and CPS effects. These findings are expected to guide development of CPLE materials in a variety of technol. fields, including 3D displays, information storage, biosensors, optical spintronics, and biol. probes.
- 23Ibanez, J. G.; Rincon, M. E.; Gutierrez-Granados, S.; Chahma, M.; Jaramillo-Quintero, O. A.; Frontana-Uribe, B. A. Conducting Polymers in the Fields of Energy, Environmental Remediation, and Chemical-Chiral Sensors. Chem. Rev. 2018, 118 (9), 4731– 4816, DOI: 10.1021/acs.chemrev.7b0048223https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXntFahu74%253D&md5=03f5131b5224a87a6fad289799d63c88Conducting Polymers in the Fields of Energy, Environmental Remediation, and Chemical-Chiral SensorsIbanez, Jorge G.; Rincon, Marina. E.; Gutierrez-Granados, Silvia; Chahma, M'hamed; Jaramillo-Quintero, Oscar A.; Frontana-Uribe, Bernardo A.Chemical Reviews (Washington, DC, United States) (2018), 118 (9), 4731-4816CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. Conducting polymers (CPs) thanks to their unique properties, structures made on-demand, new composite mixts. and possibility of deposit on a surface by chem., phys. or electrochem. methodologies, have shown in the last years a renaissance and were widely used in important fields of chem. and materials science. Due to the extensive of the literature of CPs, this review, after a concise introduction about the interrelationship between electrochem. and conducting polymers, it is focused exclusively on the following applications: energy (energy storage devices and solar cells), its use in environmental remediation (anion and cation trapping, electrocatalytic redn./oxidn. of pollutants on CP based electrodes and adsorption of pollutants) and finally electroanal. as chem. sensors in soln., gas phase and chiral mols. This review is expected to be a comprehensive, authoritative, and useful to the chem. community interested in CPs and its applications.
- 24Cai, Y.; Ni, D.; Cheng, W.; Ji, C.; Wang, Y.; Müllen, K.; Su, Z.; Liu, Y.; Chen, C.; Yin, M. Enzyme-Triggered Disassembly of Perylene Monoimide-Based Nanoclusters for Activatable and Deep Photodynamic Therapy. Angew. Chem., Int. Ed. 2020, 59 (33), 14014– 14018, DOI: 10.1002/anie.20200110724https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtVahtbfN&md5=b4891f5fdf11eb21830ededc3d814de7Enzyme-Triggered Disassembly of Perylene Monoimide-based Nanoclusters for Activatable and Deep Photodynamic TherapyCai, Yang; Ni, Dongqi; Cheng, Wenyu; Ji, Chendong; Wang, Yaling; Muellen, Klaus; Su, Zhiqiang; Liu, Ying; Chen, Chunying; Yin, MeizhenAngewandte Chemie, International Edition (2020), 59 (33), 14014-14018CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Photodynamic therapy (PDT) exhibits great potential for cancer therapy, but still suffers from nonspecific photosensitivity and poor penetration of photosensitizer. Herein, a smart perylene monoimide-based nanocluster capable of enzyme-triggered disassembly is reported as an activatable and deeply penetrable photosensitizer. A novel carboxylesterase (CE)-responsive tetrachloroperylene monoimide (P1) was synthesized and assembled with folate-decorated albumins into a nanocluster (FHP) with a diam. of circa 100 nm. Once P1 is hydrolyzed by the tumor-specific CE, FHP disassembles into ultrasmall nanoparticles (ca. 10 nm), facilitating the deep tumor penetration of FHP. Furthermore, such enzyme-triggered disassembly of FHP leads to enhanced fluorescence intensity (ca. 8-fold) and elevated singlet oxygen generation ability (ca. 4-fold), enabling in situ near-IR fluorescence imaging and promoted PDT. FHP permits remarkable tumor inhibition in vivo with minimal side effects through imaging-guided, activatable, and deep PDT. This work confirms that this cascaded multifunctional control through enzyme-triggered mol. disassembly is an effective strategy for precise cancer theranostics.
- 25Yang, Y.; da Costa, R. C.; Fuchter, M. J.; Campbell, A. J. Circularly Polarized Light Detection by a Chiral Organic Semiconductor Transistor. Nature Photon 2013, 7 (8), 634– 638, DOI: 10.1038/nphoton.2013.176There is no corresponding record for this reference.
- 26Wade, J.; Hilfiker, J. N.; Brandt, J. R.; Liirò-Peluso, L.; Wan, L.; Shi, X.; Salerno, F.; Ryan, S. T. J.; Schöche, S.; Arteaga, O. Natural Optical Activity as the Origin of the Large Chiroptical Properties in π-Conjugated Polymer Thin Films. Nat. Commun. 2020, 11 (1), 6137, DOI: 10.1038/s41467-020-19951-y29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisFWks7zJ&md5=0ac57f810b34b06d04520eac31fd5245Natural optical activity as the origin of the large chiroptical properties in π-conjugated polymer thin filmsWade, Jessica; Hilfiker, James N.; Brandt, Jochen R.; Liiro-Peluso, Letizia; Wan, Li; Shi, Xingyuan; Salerno, Francesco; Ryan, Sean T. J.; Schoche, Stefan; Arteaga, Oriol; Javorfi, Tamas; Siligardi, Giuliano; Wang, Cheng; Amabilino, David B.; Beton, Peter H.; Campbell, Alasdair J.; Fuchter, Matthew J.Nature Communications (2020), 11 (1), 6137CODEN: NCAOBW; ISSN:2041-1723. (Nature Research)Polymer thin films that emit and absorb circularly polarised light have been demonstrated with the promise of achieving important technol. advances; from efficient, high-performance displays, to 3D imaging and all-org. spintronic devices. However, the origin of the large chiroptical effects in such films has, until now, remained elusive. We investigate the emergence of such phenomena in achiral polymers blended with a chiral small-mol. additive (1-aza[6]helicene) and intrinsically chiral-sidechain polymers using a combination of spectroscopic methods and structural probes. We show that - under conditions relevant for device fabrication - the large chiroptical effects are caused by magneto-elec. coupling (natural optical activity), not structural chirality as previously assumed, and may occur because of local order in a cylinder blue phase-type organization. This disruptive mechanistic insight into chiral polymer thin films will offer new approaches towards chiroptical materials development after almost three decades of research in this area.
- 27Han, M. J.; Yun, H. S.; Cho, Y.; Kim, M.; Yang, C.; Tsukruk, V. V.; Yoon, D. K. Chiral Optoelectronic Functionalities via DNA-Organic Semiconductor Complex. ACS Nano 2021, 15 (12), 20353– 20363, DOI: 10.1021/acsnano.1c0864130https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXis1OgsLzJ&md5=9b6f14340fe11cfe3190ce04a7c7830bChiral optoelectronic functionalities via DNA-organic semiconductor complexHan, Moon Jong; Yun, Hee Seong; Cho, Yongjoon; Kim, Minkyu; Yang, Changduk; Tsukruk, Vladimir V.; Yoon, Dong KiACS Nano (2021), 15 (12), 20353-20363CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)We fabricate the bio-org. field-effect transistor (BOFET) with the DNA-perylene diimide (PDI) complex, which shows unusual chiroptical and elec. functionalities. DNA is used as the chirality-inducing scaffold and the charge-injection layer. The shear-oriented film of the DNA-PDI complex shows how the large-area periodic mol. orientation and the charge transport are related, generating drastically different optoelectronic properties at each DNA/PDI concn. The resultant BOFET reveals chiral structures with a high charge carrier mobility, photoresponsivity, and photosensitivity, reaching 3.97 cm2 V-1 s-1, 1.18 A W-1, and 7.76 × 103, resp. Interestingly, the BOFET enables the definitive response under the handedness of circularly polarized light with a high dissymmetry factor of approx. +0.14. This work highlights the natural chirality and anisotropy of DNA material and the electron cond. of org. semiconducting mols. to be mutually used in significant chiro-optoelectronic functions as an added ability to the traditional OFET.
- 28Kulkarni, C.; Meskers, S. C. J.; Palmans, A. R. A.; Meijer, E. W. Amplifying Chiroptical Properties of Conjugated Polymer Thin-Film Using an Achiral Additive. Macromolecules 2018, 51 (15), 5883– 5890, DOI: 10.1021/acs.macromol.8b0107731https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtlOqsb3P&md5=e0ef5e27400a349ababe95e5e7873ff1Amplifying Chiroptical Properties of Conjugated Polymer Thin-Film Using an Achiral AdditiveKulkarni, Chidambar; Meskers, Stefan C. J.; Palmans, Anja R. A.; Meijer, E. W.Macromolecules (Washington, DC, United States) (2018), 51 (15), 5883-5890CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)Chiral conjugated polymers bearing enantiopure side chains offer the possibility to harness the effect of chirality in org. electronic devices. However, its use is hampered by the low degree of circular polarization in absorption (gabs) in most of the conjugated polymer thin-films studied. Here we demonstrate a versatile method to significantly increase the gabs by using a few wt. percentages of a com. available achiral long-chain alc. as an additive. This additive enhances the chiroptical properties in both absorption and emission by ca. 5-10 times in the thin-films. We envisage that the alc. additive acts as a plasticizer which enhances the long-range chiral liq. cryst. ordering of the polymer chains, thereby amplifying the chiroptical properties in the thin-film. The application of this methodol. to various conjugated polymers has been demonstrated.
- 29Chochos, C. L.; Katsouras, A.; Drakopoulou, S.; Miskaki, C.; Krassas, M.; Tzourmpakis, P.; Kakavelakis, G.; Sprau, C.; Colsmann, A.; Squeo, B. M. Effects of Alkyl Side Chains Positioning and Presence of Fused Aromatic Units in the Backbone of Low-Bandgap Diketopyrrolopyrrole Copolymers on the Optoelectronic Properties of Organic Solar Cells. J. Polym. Sci., Part A: Polym. Chem. 2018, 56 (1), 138– 146, DOI: 10.1002/pola.2890132https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhslGkt7%252FP&md5=f28785f17da0b66f200b92e50582ea4dEffects of alkyl side chains positioning and presence of fused aromatic units in the backbone of low-bandgap diketopyrrolopyrrole copolymers on the optoelectronic properties of organic solar cellsChochos, Christos L.; Katsouras, Athanasios; Drakopoulou, Sofia; Miskaki, Christina; Krassas, Miron; Tzourmpakis, Pavlos; Kakavelakis, George; Sprau, Christian; Colsmann, Alexander; Squeo, Benedetta M.; Gregoriou, Vasilis G.; Kymakis, Emmanuel; Avgeropoulos, ApostolosJournal of Polymer Science, Part A: Polymer Chemistry (2018), 56 (1), 138-146CODEN: JPACEC; ISSN:0887-624X. (John Wiley & Sons, Inc.)The systematic optimization of the chem. structure of low-bandgap (LBG) donor-acceptor polymeric semiconductors is a challenging task for which accurate guidelines are yet to be detd. Several different structural and mol. parameters are crucial ingredients for obtaining LBG polymers that simultaneously possess high power conversion efficiencies, good processability in common org. solvents, and enhanced stability in org. photovoltaic devices. In this work, we present an extensive structure-optoelectronic properties-solar cell performance study on the emerging class of diketopyrrolopyrrole-based LBG polymers. In particular, we investigate alkyl side chain positioning by introducing linear alkyl side chains into two different positions (α- and β-), and the distance of the electron rich and electron deficient monomers within the repeat units of the polymer chain. We demonstrate that anchoring linear alkyl side chains to the α-positions and introducing fused moieties into the polymer backbone, can be beneficial toward maintaining photocurrents similar to the unsubstituted deriv., and concurrently exhibit better processabiliy in common org. solvents. These results can provide a design rationale towards further optimization of semiconducting polymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017.
- 30Zhang, A.; Xiao, C.; Wu, Y.; Li, C.; Ji, Y.; Li, L.; Hu, W.; Wang, Z.; Ma, W.; Li, W. Effect of Fluorination on Molecular Orientation of Conjugated Polymers in High Performance Field-Effect Transistors. Macromolecules 2016, 49 (17), 6431– 6438, DOI: 10.1021/acs.macromol.6b0144633https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhsVektr%252FF&md5=427d800606625375b3b229a3ccf20b00Effect of Fluorination on Molecular Orientation of Conjugated Polymers in High Performance Field-Effect TransistorsZhang, Andong; Xiao, Chengyi; Wu, Yang; Li, Cheng; Ji, Yunjing; Li, Lin; Hu, Wenping; Wang, Zhaohui; Ma, Wei; Li, WeiweiMacromolecules (Washington, DC, United States) (2016), 49 (17), 6431-6438CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)Fluorinated conjugated polymers have been widely used in high performance polymer solar cells, but they showed limited application in field-effect transistors (FETs). In this paper, we focus on the influence of fluorine atoms upon charge transport of conjugated polymers in FET devices. Two series of conjugated polymers without or with fluorine atoms were designed and applied into FETs. Nonfluorinated conjugated polymers show high hole mobilities up to 11.16 cm2 V-1 s-1, while fluorinated polymers exhibit low hole mobilities below 1.80 cm2 V-1 s-1. Further investigation by differential scanning calorimetry (DSC) and 2D grazing-incidence wide-angle X-ray scattering (2D-GIWAXS) reveal that fluorinated conjugated polymers show low crystallinity and "face-on" orientation in thin films, explaining their poor hole mobilities in FET devices. Our results clearly show how the chem. structures influence the charge transport properties, which can be used to design new conjugated polymers toward high performance FETs.
- 31Abdelsamie, M.; Chaney, T. P.; Yan, H.; Schneider, S. A.; Ayhan, I. A.; Gomez, E. D.; Reynolds, J. R.; Toney, M. F. Revealing Temperature-Dependent Polymer Aggregation in Solution with Small-Angle X-Ray Scattering. J. Mater. Chem. A 2022, 10 (4), 2096– 2104, DOI: 10.1039/D1TA09086K34https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XpvFCjsQ%253D%253D&md5=185dba35949e04e7142eb6ff1bf9fdaeRevealing temperature-dependent polymer aggregation in solution with small-angle X-ray scatteringAbdelsamie, Maged; Chaney, Thomas P.; Yan, Hongping; Schneider, Sebastian A.; Ayhan, I. Alperen; Gomez, Enrique D.; Reynolds, John R.; Toney, Michael F.Journal of Materials Chemistry A: Materials for Energy and Sustainability (2022), 10 (4), 2096-2104CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)Improving the morphol. of bulk heterojunction active layers remains a primary challenge for org. photovoltaics (OPVs), and much research has been devoted to achieving this through modifying OPV casting solns. to control film formation and crystallinity. Yet, the soln. conformation of conjugated polymers used in OPVs is largely unknown. Here, we report observations of temp. dependent aggregation (TDA) through small-angle X-ray scattering (SAXS) investigations of polymer conformation in chlorobenzene : dichlorobenzene casting solvent as a function of temp. for PffBT4T-2OD, a polymer known to display TDA, and its deriv. PffBT3T-2OD which displays significantly reduced TDA. We find that, upon cooling below 80°C, PffBT4T-2OD forms large cryst. aggregates in soln., while its deriv. PffBT3T-2OD forms mostly amorphous aggregates of similar size with some evidence of short-range order. This change in soln. aggregation behavior is reflected in the lack of gelation by PffBT3T-2OD upon film deposition by spin coating. Grazing-incidence wide-angle X-ray scattering (GIWAXS) revealed a preferred face-on π-π stacking orientation for PffBT3T-2OD films while PffBT4T-2OD's π-π stacking peak was isotropic. We combine these findings to suggest that the presence of cryst. seed aggregates in PffBT4T-2OD soln. quickly form an isotropic crystallite network upon cooling while PffBT3T-2OD's amorphous aggregates more slowly crystallize resulting in improved processability of PffBT3T-2OD.
- 32Kwok, J. J.; Park, K. S.; Patel, B. B.; Dilmurat, R.; Beljonne, D.; Zuo, X.; Lee, B.; Diao, Y. Understanding Solution State Conformation and Aggregate Structure of Conjugated Polymers via Small Angle X-Ray Scattering. Macromolecules 2022, 55 (11), 4353– 4366, DOI: 10.1021/acs.macromol.1c0244935https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhtlWis7%252FO&md5=e7e54ed95b767f51d69f99bc8eb75e9dUnderstanding Solution State Conformation and Aggregate Structure of Conjugated Polymers via Small Angle X-ray ScatteringKwok, Justin J.; Park, Kyung Sun; Patel, Bijal B.; Dilmurat, Rishat; Beljonne, David; Zuo, Xiaobing; Lee, Byeongdu; Diao, YingMacromolecules (Washington, DC, United States) (2022), 55 (11), 4353-4366CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)Donor-acceptor (D-A) conjugated polymers are high-performance org. electronic materials that exhibit complex aggregation behavior. Understanding the soln. state conformation and aggregation of conjugated polymers is crucial for controlling morphol. during thin-film deposition and the subsequent electronic performance. However, a precise multiscale structure of soln. state aggregates is lacking. Here, we present an in-depth small-angle X-ray scattering (SAXS) anal. of the soln. state structure of an isoindigo-bithiophene-based D-A polymer (PII-2T) in chlorobenzene and decane as our primary system. Modeling the system as a combination of hierarchical fibrillar aggregates mixed with dispersed polymers, we ext. information about conformation and multiscale aggregation and also clarify the phys. origin of features often obsd. but unaddressed or misinterpreted in small-angle scattering patterns of conjugated polymers. The persistence length of the D-A polymer extd. from SAXS agrees well with a theor. model based on the dihedral potentials. Addnl., we show that the broad high q structure factor peak seen in scattering profiles can be attributed to lamellar stacking occurring within the fibril aggregates and that the low q aggregate scattering is strongly influenced by the polymer mol. wt. Overall, the SAXS profiles of D-A polymers in general exhibit a sensitive dependence on the co-existence of fibrillar aggregate and dispersed polymer chain populations. We corroborate our findings from SAXS with electron microscopy of freeze-dried samples for direct imaging of fibrillar aggregates. Finally, we demonstrate the generality of our approach by fitting the scattering profiles of a variety of D-A polymers based on thieno-isoindigo (PTII-2T), diketopyrrolopyrrole (DPP2T-TT, DPP-BTZ, PDPP2FT-C16), naphthalenediimide (P(NDI2OD-T2)), and a conjugated block copolymer P3HT-b-DPPT-T. The results presented here establish a picture of the D-A polymer soln. state structure and provide a general method of interpreting and analyzing their scattering profiles.
- 33Albano, G.; Pescitelli, G.; Di Bari, L. Chiroptical Properties in Thin Films of π-Conjugated Systems. Chem. Rev. 2020, 120 (18), 10145– 10243, DOI: 10.1021/acs.chemrev.0c0019536https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhslCjsb3M&md5=22166eb37a9a7a4ef769e7de4a7345cdChiroptical Properties in Thin Films of π-Conjugated SystemsAlbano, Gianluigi; Pescitelli, Gennaro; Di Bari, LorenzoChemical Reviews (Washington, DC, United States) (2020), 120 (18), 10145-10243CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. Chiral π-conjugated mols. provide new materials with outstanding features for current and perspective applications, esp. in the field of optoelectronic devices. In thin films, processes such as charge conduction, light absorption, and emission are governed not only by the structure of the individual mols. but also by their supramol. structures and intermol. interactions to a large extent. Electronic CD, ECD, and its emission counterpart, circularly polarized luminescence, CPL, provide tools for studying aggregated states and the key properties to be sought for designing innovative devices. In this review, we shall present a comprehensive coverage of chiroptical properties measured on thin films of org. π-conjugated mols. In the first part, we shall discuss some general concepts of ECD, CPL, and other chiroptical spectroscopies, with a focus on their applications to thin film samples. In the following, we will overview the existing literature on chiral π-conjugated systems whose thin films have been characterized by ECD and/or CPL, as well other chiroptical spectroscopies. Special emphasis will be put on systems with large dissymmetry factors (gabs and glum) and on the application of ECD and CPL to derive structural information on aggregated states.
- 34Pescitelli, G.; Omar, O. H.; Operamolla, A.; Farinola, G. M.; Di Bari, L. Chiroptical Properties of Glucose-Substituted Poly(p-Phenylene-Ethynylene)s in Solution and Aggregate State. Macromolecules 2012, 45 (24), 9626– 9630, DOI: 10.1021/ma301919u37https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhvVahsLzI&md5=6060c1de49e4ec59d2686ec9c508b87cChiroptical Properties of Glucose-Substituted Poly(p-phenylene-ethynylene)s in Solution and Aggregate StatePescitelli, Gennaro; Omar, Omar Hassan; Operamolla, Alessandra; Farinola, Gianluca M.; Di Bari, LorenzoMacromolecules (Washington, DC, United States) (2012), 45 (24), 9626-9630CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)The aggregation behavior of two D-glucose-substituted phenyleneethynylenes, an alternate oligomeric copolymer (AP) and a oligomeric homopolymer (HO), was investigated by means of UV-vis absorption, CD (CD) and fluorescence spectroscopy. CD reveals superior capability to detect the early stages of aggregation and to provide information about aggregate geometries. The multiband CD spectrum of the AP and of analogous chiral PPEs is rationalized on the basis of the exciton coupling between vibronic transitions localized on proximate portions of the chromophoric chains.
- 35Lu, J.; Xue, Y.; Bernardino, K.; Zhang, N.-N.; Gomes, W. R.; Ramesar, N. S.; Liu, S.; Hu, Z.; Sun, T.; de Moura, A. F. Enhanced Optical Asymmetry in Supramolecular Chiroplasmonic Assemblies with Long-Range Order. Science 2021, 371 (6536), 1368– 1374, DOI: 10.1126/science.abd857638https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXnsVyqt7c%253D&md5=ba0509166c9a8d6cb7d64f6c0af1bf79Enhanced optical asymmetry in supramolecular chiroplasmonic assemblies with long-range orderLu, Jun; Xue, Yao; Bernardino, Kalil; Zhang, Ning-Ning; Gomes, Weverson R.; Ramesar, Naomi S.; Liu, Shuhan; Hu, Zheng; Sun, Tianmeng; de Moura, Andre Farias; Kotov, Nicholas A.; Liu, KunScience (Washington, DC, United States) (2021), 371 (6536), 1368-1374CODEN: SCIEAS; ISSN:1095-9203. (American Association for the Advancement of Science)Chiral assemblies of plasmonic nanoparticles are known for strong CD but not for high optical asymmetry, which is limited by the unfavorable combination of elec. and magnetic field components compounded by strong scattering. Here, we show that these limitations can be overcome by the long-range organization of nanoparticles in a manner similar to the liq. crystals and found in helical assemblies of gold nanorods with human islet amyloid polypeptides. A strong, polarization-dependent spectral shift and the reduced scattering of energy states with antiparallel orientation of dipoles activated in assembled helixes increased optical asymmetry g-factors by a factor of more than 4600. The liq. crystal-like color variations and the nanorod-accelerated fibrillation enable drug screening in complex biol. media. Improvement of long-range order can also provide structural guidance for the design of materials with high optical asymmetry.
- 36Prinsen, P.; Van Der Schoot, P. Shape and Director-Field Transformation of Tactoids. Phys. Rev. E 2003, 68 (2), 021701, DOI: 10.1103/PhysRevE.68.02170139https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXntFaisr4%253D&md5=4e26d7c0989b8c9f95bfc3328f3720ffShape and director-field transformation of tactoidsPrinsen, Peter; van der Schoot, PaulPhysical Review E: Statistical, Nonlinear, and Soft Matter Physics (2003), 68 (2-1), 021701/1-021701/11CODEN: PRESCM ISSN:. (American Physical Society)Tactoids are droplets of a nematic phase that under suitable conditions form in dispersions of elongated colloidal particles. The authors theor. study the shape and the director-field configuration of such droplets for the case where a planar anchoring of the director field to the interface is favored. A min. of four regimes can be identified in which the droplets have a different structure. Large droplets tend to be nearly spherical with a director field that is bipolar if the surface tension is strongly anisotropic and homogeneous if this is not so. Small droplets can become very elongated and spindlelike if the surface tension is sufficiently anisotropic. Depending on the anchoring strength, the director field is then either homogeneous or bipolar. The more elongated the tactoid, the more strongly it resists the crossing over from a homogeneous to a bipolar structure. This should have implications for the nucleation rate of the nematic phase. The authors' calcns. qual. describe the size dependence of the aspect ratio of tactoids found in recent expts.
- 37Weirich, K. L.; Banerjee, S.; Dasbiswas, K.; Witten, T. A.; Vaikuntanathan, S.; Gardel, M. L. Liquid Behavior of Cross-Linked Actin Bundles. Proc. Natl. Acad. Sci. U. S. A. 2017, 114 (9), 2131– 2136, DOI: 10.1073/pnas.161613311440https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXislWgsb8%253D&md5=f4d4386152e8b75505ee77d71f376c23Liquid behavior of cross-linked actin bundlesWeirich, Kimberly L.; Banerjee, Shiladitya; Dasbiswas, Kinjal; Witten, Thomas A.; Vaikuntanathan, Suriyanarayanan; Gardel, Margaret L.Proceedings of the National Academy of Sciences of the United States of America (2017), 114 (9), 2131-2136CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)The actin cytoskeleton is a crit. regulator of cytoplasmic architecture and mechanics, essential in a myriad of physiol. processes. Here we demonstrate a liq. phase of actin filaments in the presence of the physiol. cross-linker, filamin. Filamin condenses short actin filaments into spindle-shaped droplets, or tactoids, with shape dynamics consistent with a continuum model of anisotropic liqs. We find that cross-linker d. controls the droplet shape and deformation timescales, consistent with a variable interfacial tension and viscosity. Near the liq.-solid transition, cross-linked actin bundles show behaviors reminiscent of fluid threads, including capillary instabilities and contraction. These data reveal a liq. droplet phase of actin, demixed from the surrounding soln. and dominated by interfacial tension. These results suggest a mechanism to control organization, morphol., and dynamics of the actin cytoskeleton.
- 38Verhoeff, A. A.; Bakelaar, I. A.; Otten, R. H. J.; Van Der Schoot, P.; Lekkerkerker, H. N. W. Tactoids of Plate-Like Particles: Size, Shape, and Director Field. Langmuir 2011, 27 (1), 116– 125, DOI: 10.1021/la104128m41https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhsFSkurfL&md5=15ec962c5c655aa20a2cf61efbcb73c2Tactoids of plate-like particles: size, shape, and director fieldVerhoeff, A. A.; Bakelaar, I. A.; Otten, R. H. J.; van der Schoot, P.; Lekkerkerker, H. N. W.Langmuir (2011), 27 (1), 116-125CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)We studied, by means of polarized light microscopy, the shape and director field of nematic tactoids as a function of their size in dispersions of colloidal gibbsite platelets in polar and apolar solvents. Because of the homeotropic anchoring of the platelets to the interface, we found large tactoids to be spherical with a radial director field, whereas small tactoids turn out to have an oblate shape and a homogeneous director field, in accordance with theor. predictions. The transition from a radial to a homogeneous director field seems to proceed via two different routes depending in our case on the solvent. In one route, the what presumably is a hedgehog point defect in the center of the tactoid transforms into a ring defect with a radius that presumably goes to infinity with decreasing drop size. In the other route, the hedgehog defect is displaced from the center to the edge of the tactoid, where it becomes virtual again going to infinity with decreasing drop size. Furthermore, quant. anal. of the tactoid properties provides us with useful information on the ratio of the splay elastic const. and the anchoring strength and the ratio of the anchoring strength and the surface tension.
- 39Sutton, C.; Körzdörfer, T.; Gray, M. T.; Brunsfeld, M.; Parrish, R. M.; Sherrill, C. D.; Sears, J. S.; Brédas, J.-L. Accurate Description of Torsion Potentials in Conjugated Polymers Using Density Functionals with Reduced Self-Interaction Error. J. Chem. Phys. 2014, 140 (5), 054310, DOI: 10.1063/1.486321842https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXjslOksL0%253D&md5=fb3aca3d1b5e96451f9f711e051d3069Accurate description of torsion potentials in conjugated polymers using density functionals with reduced self-interaction errorSutton, Christopher; Korzdorfer, Thomas; Gray, Matthew T.; Brunsfeld, Max; Parrish, Robert M.; Sherrill, C. David; Sears, John S.; Bredas, Jean-LucJournal of Chemical Physics (2014), 140 (5), 054310/1-054310/9CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)We investigate the torsion potentials in two prototypical π-conjugated polymers, polyacetylene and polydiacetylene, as a function of chain length using different flavors of d. functional theory. Our study provides a quant. anal. of the delocalization error in std. semilocal and hybrid d. functionals and demonstrates how it can influence structural and thermodn. properties. The delocalization error is quantified by evaluating the many-electron self-interaction error (MESIE) for fractional electron nos., which allows us to establish a direct connection between the MESIE and the error in the torsion barriers. The use of non-empirically tuned long-range cor. hybrid functionals results in a very significant redn. of the MESIE and leads to an improved description of torsion barrier heights. In addn., we demonstrate how our anal. allows the detn. of the effective conjugation length in polyacetylene and polydiacetylene chains. (c) 2014 American Institute of Physics.
- 40Körzdörfer, T.; Brédas, J.-L. Organic Electronic Materials: Recent Advances in the DFT Description of the Ground and Excited States Using Tuned Range-Separated Hybrid Functionals. Acc. Chem. Res. 2014, 47 (11), 3284– 3291, DOI: 10.1021/ar500021t43https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2cnosFaltg%253D%253D&md5=378dd3ab4b06d00152d606ed0f7c933fOrganic electronic materials: recent advances in the DFT description of the ground and excited states using tuned range-separated hybrid functionalsKorzdorfer Thomas; Bredas Jean-LucAccounts of chemical research (2014), 47 (11), 3284-91 ISSN:.CONSPECTUS: Density functional theory (DFT) and its time-dependent extension (TD-DFT) are powerful tools enabling the theoretical prediction of the ground- and excited-state properties of organic electronic materials with reasonable accuracy at affordable computational costs. Due to their excellent accuracy-to-numerical-costs ratio, semilocal and global hybrid functionals such as B3LYP have become the workhorse for geometry optimizations and the prediction of vibrational spectra in modern theoretical organic chemistry. Despite the overwhelming success of these out-of-the-box functionals for such applications, the computational treatment of electronic and structural properties that are of particular interest in organic electronic materials sometimes reveals severe and qualitative failures of such functionals. Important examples include the overestimation of conjugation, torsional barriers, and electronic coupling as well as the underestimation of bond-length alternations or excited-state energies in low-band-gap polymers. In this Account, we highlight how these failures can be traced back to the delocalization error inherent to semilocal and global hybrid functionals, which leads to the spurious delocalization of electron densities and an overestimation of conjugation. The delocalization error for systems and functionals of interest can be quantified by allowing for fractional occupation of the highest occupied molecular orbital. It can be minimized by using long-range corrected hybrid functionals and a nonempirical tuning procedure for the range-separation parameter. We then review the benefits and drawbacks of using tuned long-range corrected hybrid functionals for the description of the ground and excited states of π-conjugated systems. In particular, we show that this approach provides for robust and efficient means of characterizing the electronic couplings in organic mixed-valence systems, for the calculation of accurate torsional barriers at the polymer limit, and for the reliable prediction of the optical absorption spectrum of low-band-gap polymers. We also explain why the use of standard, out-of-the-box range-separation parameters is not recommended for the DFT and/or TD-DFT description of the ground and excited states of extended, pi-conjugated systems. Finally, we highlight a severe drawback of tuned range-separated hybrid functionals by discussing the example of the calculation of bond-length alternation in polyacetylene, which leads us to point out the challenges for future developments in this field.
- 41Spano, F. C. The Spectral Signatures of Frenkel Polarons in H- and J-Aggregates. Acc. Chem. Res. 2010, 43 (3), 429– 439, DOI: 10.1021/ar900233v44https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsFKgurzL&md5=a66d2effbaf73a403bf00e6e198efe0aThe Spectral Signatures of Frenkel Polarons in H- and J-AggregatesSpano, Frank C.Accounts of Chemical Research (2010), 43 (3), 429-439CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)A review. Electronic excitations in small aggregates, thin films, and crystals of conjugated org. mols. play a fundamental role in the operation of a wide array of org.-based devices including solar cells, transistors, and light-emitting diodes. Such excitations, or excitons, are generally spread out over several mols.: a balance between the delocalizing influence of resonant intermol. coupling and the localizing influence of static and dynamic disorder dets. the coherence range of the exciton. Because of the soft nature of org. materials, significant nuclear relaxation in the participating mols. also accompanies the electronic excitations. To properly understand energy or charge transport, 1 must treat intermol. (excitonic) coupling, electron-vibrational coupling, and disorder on equal footing. In this Account, the authors review the key elements of a theor. approach based on a multiparticle representation that describes electronic excitations in org. materials as vibronic excitations surrounded by a field of vibrational excitations. Such composite excitations are appropriately called Frenkel excitonic polarons. For many conjugated mols., the bulk of the nuclear reorganization energy following electronic excitation arises from the elongation of a sym. vinyl stretching mode with energy ∼1400 cm-1. To appreciate the impact of aggregation, the authors study how the vibronic progression of this mode, which dominates the isolated (solvated) mol. absorption and emission spectra, is distorted when mols. are close enough to interact with each other. As the authors demonstrate in this Account, the nature of the distortion provides a wealth of information about how the mols. are packed, the strength of the excitonic interactions between mols., the no. of mols. that are coherently coupled, and the nature of the disorder. The aggregation-induced deviations from the Poissonian distribution of vibronic peak intensities take on 2 extremes identified with ideal H- and J-aggregates. The sign of the nearest neighbor electronic coupling, pos. for H and neg. for J, distinguishes the 2 basic aggregate forms. For several decades, researchers have known that H-aggregates exhibit blue-shifted absorption spectra and are subradiant while J-aggregates exhibit the opposite behavior (red shifted absorption and superradiance). However, the exact inclusion of exciton-vibrational coupling reveals several more distinguishing traits between the 2 aggregate types: in H(J)-aggregates the ratio of the 1st 2 vibronic peak intensities in the absorption spectrum decreases (increases) with increasing excitonic coupling, while the ratio of the 0-0 to 0-1 emission intensities increases (decreases) with disorder and increases (decreases) with increasing temp. These 2 extreme behaviors provide the framework for understanding absorption and emission in more complex morphologies, such as herringbone packing in oligo(phenylene vinylene)s, oligothiophenes and polyacene crystals, as well as the polymorphic packing arrangements obsd. in carotenoids.
- 42Francis, C.; Fazzi, D.; Grimm, S. B.; Paulus, F.; Beck, S.; Hillebrandt, S.; Pucci, A.; Zaumseil, J. Raman Spectroscopy and Microscopy of Electrochemically and Chemically Doped High-Mobility Semiconducting Polymers. Journal of Materials Chemistry C 2017, 5 (25), 6176– 6184, DOI: 10.1039/C7TC01277B45https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXosFSqtLo%253D&md5=530072111b3ddae9109ff463e82166b8Raman spectroscopy and microscopy of electrochemically and chemically doped high-mobility semiconducting polymersFrancis, C.; Fazzi, D.; Grimm, S. B.; Paulus, F.; Beck, S.; Hillebrandt, S.; Pucci, A.; Zaumseil, J.Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2017), 5 (25), 6176-6184CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)The polaronic nature of two high-mobility hole-conducting polymers (PBTTT and DPPT-TT) was studied by Raman spectroscopy and d. functional theory (DFT) calcns. Chem. and electrochem. hole doping of these polymers leads to characteristic changes in the intensity ratios of the Raman active C=C stretching modes but no significant frequency shifts. The data indicate a localization of pos. polarons on the electron-rich thienothiophene cores that are present in both polymers. DFT calcns. show that the Raman intensity ratio variations are most likely caused by the local elec. field that originates from neg. charged dopant mols. or electrolyte anions and the pos. polaron on the polymer chain. The characteristic changes in the Raman mode intensity ratios with the degree of doping enable in situ mapping of charge carrier concn. in the channel of electrolyte-gated polymer transistors with high spatial resoln.
- 43Fei, Z.; Boufflet, P.; Wood, S.; Wade, J.; Moriarty, J.; Gann, E.; Ratcliff, E. L.; McNeill, C. R.; Sirringhaus, H.; Kim, J.-S. Influence of Backbone Fluorination in Regioregular Poly(3-Alkyl-4-Fluoro)Thiophenes. J. Am. Chem. Soc. 2015, 137 (21), 6866– 6879, DOI: 10.1021/jacs.5b0278546https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXovVShtbw%253D&md5=02a47d4e12034011b943d1fb4aa7f315Influence of Backbone Fluorination in Regioregular Poly(3-alkyl-4-fluoro)thiophenesFei, Zhuping; Boufflet, Pierre; Wood, Sebastian; Wade, Jessica; Moriarty, John; Gann, Eliot; Ratcliff, Erin L.; McNeill, Christopher R.; Sirringhaus, Henning; Kim, Ji-Seon; Heeney, MartinJournal of the American Chemical Society (2015), 137 (21), 6866-6879CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)We report two strategies toward the synthesis of 3-alkyl-4-fluorothiophenes contg. straight (hexyl and octyl) and branched (2-ethylhexyl) alkyl groups. We demonstrate that treatment of the dibrominated monomer with 1 equiv of alkyl Grignard reagent leads to the formation of a single regioisomer as a result of the pronounced directing effect of the fluorine group. Polymn. of the resulting species affords highly regioregular poly(3-alkyl-4-fluoro)thiophenes. Comparison of their properties to those of the analogous non-fluorinated polymers shows that backbone fluorination leads to an increase in the polymer ionization potential without a significant change in optical band gap. Fluorination also results in an enhanced tendency to aggregate in soln., which is ascribed to a more co-planar backbone on the basis of Raman and DFT calcns. Av. charge carrier mobilities in field-effect transistors are found to increase by up to a factor of 5 for the fluorinated polymers.
- 44Wood, S.; Hollis, J. R.; Kim, J.-S. Raman Spectroscopy as an Advanced Structural Nanoprobe for Conjugated Molecular Semiconductors. J. Phys. D: Appl. Phys. 2017, 50 (7), 073001, DOI: 10.1088/1361-6463/50/7/07300147https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXptFKrtbw%253D&md5=c0f6607175929bcbfdd444504e64e49bRaman spectroscopy as an advanced structural nanoprobe for conjugated molecular semiconductorsWood, Sebastian; Hollis, Joseph Razzell; Kim, Ji-SeonJournal of Physics D: Applied Physics (2017), 50 (7), 073001/1-073001/32CODEN: JPAPBE; ISSN:0022-3727. (IOP Publishing Ltd.)A review. Raman spectroscopy has emerged as a powerful and important characterization tool for probing mol. semiconducting materials. The useful optoelectronic properties of these materials arise from the delocalised π-electron d. in the conjugated core of the mol., which also results in large Raman scattering cross-sections and a strong coupling between its electronic states and vibrational modes. For this reason, Raman spectroscopy offers a unique insight into the properties of mol. semiconductors, including: chem. structure, mol. conformation, mol. orientation, and fundamental photo- and electro-chem. processes-all of which are critically important to the performance of a wide range of optical and electronic org. semiconductor devices. Exptl., Raman spectroscopy is nonintrusive, non-destructive, and requires no special sample prepn., and so is suitable for a wide range of in situ measurements, which are particularly relevant to issues of thermal and photochem. stability. Here we review the development of the family of Raman spectroscopic techniques, which have been applied to the study of conjugated mol. semiconductors. We consider the suitability of each technique for particular circumstances, and the unique insights it can offer, with a particular focus on the significance of these measurements for the continuing development of stable, high performance org. electronic devices.
Supporting Information
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acscentsci.3c00775.
Materials and methods for polymer synthesis and mesophase samples, experimental details and analysis, as well as additional figures and tables (PDF)
In-situ cross polarized optical microscopy (CPOM) movie of a 100 mg/mL DPP-T2M2 polymer solution monitored during thermal heating and cooling (AVI)
In-situ cross polarized optical microscopy (CPOM) movie of a 100 mg/mL DPP-T4 polymer solution monitored during thermal heating and cooling (AVI)
In-situ cross polarized optical microscopy (CPOM) movie of a 100 mg/mL DPP-T2F2 polymer solution monitored during thermal heating and cooling (AVI)
SAXS model (ZIP)
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