Incorporation of fused tetrathiafulvalene units in a DPP–terthiophene copolymer for air stable solution processable organic field effect transistors

Abstract

A new terthiophene–diketopyrrolopyrrole (DPP) copolymer has been synthesised in which the central thiophene ring within the terthiophene repeat unit is attached to a fused tetrathiafulvalene (TTF). The electrochemical and absorption data of the polymer, p(DPP-TTF), are presented, and the multi-redox states are investigated by UV-vis spectroelectrochemistry. Bottom gate/bottom contact field effect transistors were fabricated from films of p(DPP-TTF) annealed at 200 °C. The material, which under these conditions forms a fibrous structure, exhibited hole mobilities of 4 ± 2 × 10−2 cm2 V−1 s−1 with an on/off ratio of 1 × 104. The transistors showed little sign of degradation over 15 days of exposure under ambient conditions, demonstrating excellent air-stability. This characteristic is attributed to the incorporation of the TTF unit into the polymer.