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

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.