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

Abstract

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-C61 -butyric acid methyl ester (PC61 BM) bulk heterojunction as photoactive layer, and sandwiched MoO3 interlayer as a charge-transport interlayer exhibits outstanding photodetection characteristics such as a photosensitivity (Ilight /Idark ) of 2.9 × 106 , photoresponsivity (R) of 8.6 × 103 A W-1 , detectivity (D*) of 3.4 × 1014 Jones, and external quantum efficiency of 3 × 106 % under weak light illumination of 32 µW 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.