Solution-Processed Small-Molecule Bulk Heterojunction Ambipolar Transistors

Solution‐processed small‐molecule bulk heterojunction (BHJ) ambipolar organic thin‐film transistors are fabricated based on a combination of [2‐phenylbenzo[d,d']thieno[3,2‐b;4,5‐b']dithiophene (P‐BTDT) : 2‐(4‐n‐octylphenyl)benzo[d,d']thieno[3,2‐b;4,5‐b']dithiophene (OP‐BTDT)] and C60. Treating high electrical performance vacuum‐deposited P‐BTDT organic semiconductors with a newly developed solution‐processed organic semiconductor material, OP‐BTDT, in an optimized ratio yields a solution‐processed p‐channel organic semiconductor blend with carrier mobility as high as 0.65 cm2 V−1 s−1. An optimized blending of P‐BTDT:OP‐BTDT with the n‐channel semiconductor, C60, results in a BHJ ambipolar transistor with balanced carrier mobilities for holes and electrons of 0.03 and 0.02 cm2 V−1 s−1, respectively. Furthermore, a complementary‐like inverter composed of two ambipolar thin‐film transistors is demonstrated, which achieves a gain of 115. Solution‐processed small‐molecule bulk heterojunction (BHJ) ambipolar organic thin‐film transistors fabricated by blending two p‐channel benzo[d,d']thieno[3,2‐b;4,5‐b']dithiophene (BTDT) derivatives with n‐channel C60 result in balanced hole and electron carrier mobilities. A complementary‐like inverter composed of two ambipolar thin‐film transistors with a gain of 115 is achieved.