A Novel Hybrid-Layered Organic Phototransistor Enables Efficient Intermolecular Charge Transfer and Carrier Transport for Ultrasensitive Photodetection

摘要

The interfacial charge effect is crucial for high-sensitivity organic phototransistors (OPTs), but conventional layered and hybrid OPTs have a trade-off in balancing the separation, transport, and recombination of photogenerated charges, consequently impacting the device performance. Herein, a novel hybrid-layered phototransistor (HL-OPT) is reported with significantly improved photodetection performance, which takes advantages of both the charge-trapping effect (CTE) and efficient carrier transport. The HL-OPT consisting of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) as conduction channel, C8-BTBT:[6,6]-phenyl-C-61-butyric acid methyl ester (PC61BM) bulk heterojunction as photoactive layer, and sandwiched MoO3 interlayer as a charge-transport interlayer exhibits outstanding photodetection characteristics such as a photosensitivity (I-light/I-dark) of 2.9 x 10(6), photoresponsivity (R) of 8.6 x 10(3) A W-1, detectivity (D*) of 3.4 x 10(14) Jones, and external quantum efficiency of 3 x 10(6)% under weak light illumination of 32 mu W cm(-2). The mechanism and strategy described here provide new insights into the design and optimization of high-performance OPTs spanning the ultraviolet and near infrared (NIR) range as well as fundamental issues pertaining to the electronic and photonic properties of the devices.