2,5-Bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4-(2H,5H)-dione-Based Donor–Acceptor Alternating Copolymer Bearing 5,5′-Di(thiophen-2-yl)-2,2′-biselenophene Exhibiting 1.5 cm2·V–1·s–1 Hole Mobility in Thin-Film Transistors

Abstract

A novel diketopyrrolopyrrole-based π-conjugated copolymer P(DPP-alt-DTBSe), 5, and a known copolymer P(DPP-alt-QT), 4, have been synthesized in 80–90% yield using the Stille coupling reaction. The molecular weights of 4 and 5 are 58 781 and 19 271 g/mol, respectively, with polydispersity values of 3.25–3.35. A relatively small band gap of 1.32–1.39 eV and excellent solubility in organic solvents were achieved in the two polymers. Thin-film transistors made of 5 exhibit outstanding performance (e.g., μ > 1.0–1.5 cm²·V^–1·s^–1, I_on/I_off > 10⁵–10⁶) with a conventional n-octyltrichlorosilane–SiO₂ gate dielectric.