High‐Performance UV‐Sensitive Organic Phototransistors Based on Benzo[1,2‐b:4,5‐b′]dithiophene Dimers Linked with Unsaturated Bonds

Obvious differentiated response of organic phototransistors (OPTs) to the lights with different wavelengths is a challenge but a prerequisite for wavelength‐selective applications. In this manuscript, highly UV‐sensitive OPTs are fabricated based on benzo[1,2‐ b :4,5‐ b′ ]dithiophene dimers (BBDT, BBDTE, and BBDTY). The BBDTE‐based organic single‐crystal transistors (OSCTs), which show carrier mobility up to 1.62 cm 2 V −1 s −1 , exhibit a maximum photoresponsivity up to 9821 A W −1 and a maximum photosensitivity up to 10 5 towards UV light (37 μW cm −2 ), and the photosensitivity observed within tested light intensity range is unexpectedly stable. The BBDTY‐based OPTs also exhibit differentiated response between UV and visible lights, even with thin‐film state of organic semiconductor, and the highest photoresponsivity and photosensitivity to UV light reached 9336 A W −1 and 4429, respectively. This selective and highly sensitive performance enables unsaturated bond‐linked benzo[1,2‐ b :4,5‐ b′ ]dithiophene dimers promising candidates for UV detectors.