Thiazole Imide‐Based All‐Acceptor Homopolymer: Achieving High‐Performance Unipolar Electron Transport in Organic Thin‐Film Transistors

High‐performance unipolar n‐type polymer semiconductors are critical for advancing the field of organic electronics, which relies on the design and synthesis of new electron‐deficient building blocks with good solubilizing capability, favorable geometry, and optimized electrical properties. Herein, two novel imide‐functionalized thiazoles, 5,5′‐bithiazole‐4,4′‐dicarboxyimide (BTzI) and 2,2′‐bithiazolothienyl‐4,4′,10,10′‐tetracarboxydiimide (DTzTI), are successfully synthesized. Single crystal analysis and physicochemical study reveal that DTzTI is an excellent building block for constructing all‐acceptor homopolymers, and the resulting polymer poly(2,2′‐bithiazolothienyl‐4,4′,10,10′‐tetracarboxydiimide) (PDTzTI) exhibits unipolar n‐type transport with a remarkable electron mobility (μe) of 1.61 cm2 V−1 s−1, low off‐currents (Ioff) of 10−10−10−11 A, and substantial current on/off ratios (Ion/Ioff) of 107−108 in organic thin‐film transistors. The all‐acceptor homopolymer shows distinctive advantages over prevailing n‐type donor−acceptor copolymers, which suffer from ambipolar transport with high Ioffs > 10−8 A and small Ion/Ioffs < 105. The results demonstrate that the all‐acceptor approach is superior to the donor−acceptor one, which results in unipolar electron transport with more ideal transistor performance characteristics. Electron‐deficient thiazole imides are synthesized, which enables the development of all‐acceptor homopolymers. The polymer PDTzTI exhibits a remarkable electron mobility of 1.61 cm2 V−1 s−1 with minimal off‐currents of 10−10−10−11 A and substantial current on/off ratios of 107−108 in the saturation regime, thus showing distinct advantages over traditional donor−acceptor copolymers, which suffer from high off‐currents and small on/off ratios.