Deep Ultraviolet Phototransistor Based on Thiophene‐Fluorobenzene Oligomer with High Mobility and Performance†

Comprehensive Summary Deep ultraviolet (UV) photodetectors have important applications in the industrial and military fields. However, little research has been reported on organic phototransistors (OPTs) in the deep ultraviolet range. Here, a novel organic semiconductor containing a small torsion angle and low π‐conjugation 2,2':5',2”‐terthiophene groups, oF‐PTTTP, is designed and synthesized, which exhibits high carrier mobility and unique deep ultraviolet response. Accordingly, an OPT based on oF‐PTTTP single crystal shows high responsivity to deep‐UV light. The photodetectors achieve high photoresponsivity ( R ) of 857 A/W and detectivity ( D *) of 3.2×10 15 Jones under 280 nm light illumination (only 95 nW·cm –2 ). To the best of our knowledge, 280 nm is the deepest detection wavelength reported for organic phototransistors and this work presents a new molecule design concept for organic phototransistors with deep‐UV detection.