Electrical Double-Layer Transistors Comprising Block Copolymer Electrolytes for Low-Power-Consumption Photodetectors

Electrical double-layer transistors (EDLTs) have received extensive research attention owing to their exciting advantages of low working voltage, high biocompatibility, and sensitive interfacial properties in ultrasensitive portable sensing applications. Therefore, it is of great interest to reduce photodetectors’ operating voltage and power consumption by utilizing photo-EDLT. In this study, a series of block copolymers (BCPs) of poly(4-vinylpyridine)-block-poly(ethylene oxide) (P4VP-b-PEO) with different compositions were applied to formulate polyelectrolyte with indigo carmine salt in EDLT. Accordingly, PEO conduces ion conduction in the BCP electrolyte and enhances the carrier transport capability in the semiconducting channel; P4VP boosts the photocurrent by providing charge-trapping sites during light illumination. In addition, the severe aggregation of PEO is mitigated by forming a BCP structure with P4VP, enhancing the stability and photoresponse of the photo-EDLT. By optimizing the BCP composition, EDLT comprising P4VP16k-b-PEO5k and indigo carmine provides the highest specific detectivity of 2.1 × 107 Jones, along with ultralow power consumptions of 0.59 nW under 450 nm light illumination and 0.32 pW under dark state. The results indicate that photo-EDLT comprising the BCP electrolyte is a practical approach to reducing phototransistors’ operating voltage and power consumption.


Figure S2 .
Figure S2.CV profiles of DNTT, indigo carmine, P4VP, PEO, P3E1, P1E1, and P1E7.Note that the measurement was conducted in a three-electrodes system with a platinum auxiliary electrode and an Ag/AgCl reference electrode, and the sweeping rate was fixed at 100 mV s -1 .

Figure S4 .
Figure S4.Water contact angle (CA) of the block copolymer polyelectrolyte films and their analogs of P4VP and PEO with indigo carmine.

Figure S12 .
Figure S12.Hysteresis of the EDLT comprising (a) P3E1, (b) P1E1, and (c) P1E7 with indigo carmine in the dark state or under 450-nm light illumination.Note that the gate voltage applied was swept forward from 1 to -3 V and backward from -3 to 1 V.The drain voltage was fixed at -1 V and the light intensity was 155 mW cm -2 .

Figure S13 .
Figure S13.Transfer characteristics of the EDLT comprising (a) P4VP:indigo carmine and (b) PEO:indigo carmine in the dark state or under 450-nm light illumination.Notethat the gate voltage applied in transfer curves was swept from 1 to -3 V, the drain voltage was fixed at -1 V, and the light intensity was 34 mW cm -2 .

Figure S15 .
Figure S15.Transfer characteristics of the EDLT comprising (a) P3E1, (b) P1E1, and (c) P1E7 without indigo carmine in the dark state or under 450-nm light illumination.

Figure S16 .
Figure S16.Transient photocurrent characteristics of the reference EDLT comprising polyelectrolytes with P4VP or PEO.Note that the drain voltage was fixed at -1 V, and the intensity of 450-nm light applied within 30-90 s was 155 mW cm -2 .

Figure S18 .
Figure S18.Transient photocurrent characteristics of the EDLT comprising polymer blend electrolytes with varied compositions.Note that the drain voltage was fixed at -1 V, and the intensity of 450-nm light applied within 30-90 s was 155 mW cm -2 .

Figure S20 .
Figure S20.Transient photocurrent characteristics of P3E1 under different light intensities.Note that the drain voltage was fixed at -1 V.

Figure S21 .
Figure S21.(a) Dark current noise of the EDLT devices.(b) Transient photocurrent characteristics of the EDLT comprising BCP electrolytes with varied compositions.Note that the drain voltage was fixed at -3 V, and the intensity of 450-nm light applied within 30-90 s was 155 mW cm -2 .

Figure S23 .
Figure S23.Comparison study of BCP's molecular weight and block ratio and the device performance: (a) transfer curves, (b) transient photocurrent characteristics, and (c) dark current noise of P4E1:indigo carmine.Note that the drain voltage was fixed at