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 (mu(e)) of 1.61 cm(2) V-1 s(-1), low off-currents (I-off) of 10(-10)-10(-11) A, and substantial current on/off ratios (I-on/I-off) of 10(7)-10(8) 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 I(off)s > 10(-8) A and small I-on/I(off)s < 10(5). 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.