Electrical Double-LayerTransistors Comprising BlockCopolymer Electrolytes for Low-Power-Consumption Photodetectors

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Electrical double-layer transistors (EDLTs) have receivedextensiveresearch attention owing to their exciting advantages of low workingvoltage, high biocompatibility, and sensitive interfacial propertiesin ultrasensitive portable sensing applications. Therefore, it isof great interest to reduce photodetectors’ operating voltageand power consumption by utilizing photo-EDLT. In this study, a seriesof block copolymers (BCPs) of poly(4-vinylpyridine)-block-poly(ethylene oxide) (P4VP-b-PEO) with differentcompositions were applied to formulate polyelectrolyte with indigocarmine salt in EDLT. Accordingly, PEO conduces ion conduction inthe BCP electrolyte and enhances the carrier transport capabilityin the semiconducting channel; P4VP boosts the photocurrent by providingcharge-trapping sites during light illumination. In addition, thesevere aggregation of PEO is mitigated by forming a BCP structurewith P4VP, enhancing the stability and photoresponse of the photo-EDLT.By optimizing the BCP composition, EDLT comprising P4VP16k-b-PEO5k and indigo carmine providesthe highest specific detectivity of 2.1 × 107 Jones,along with ultralow power consumptions of 0.59 nW under 450 nm lightillumination and 0.32 pW under dark state. The results indicate thatphoto-EDLT comprising the BCP electrolyte is a practical approachto reducing phototransistors’ operating voltage and power consumption.