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

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 (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 × 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.