π-Conjugated polymers derived from 2,5-bis(2-decyltetradecyl)-3,6-di(selenophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione for high-performance thin film transistors

Novel 2,5-bis(2-decyltetradecyl)-3,6-di(selenophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (DSDPP)-containing conjugated polymers with different donor monomers were synthesized via a Pd(0)-catalyzed Stille coupling reaction. Solubilized 2-decyltetradecyl (DT) groups were tethered to the N-atoms in diketopyrrolopyrrole (DPP). As electron-donating units, bithiophene (BT) and a π-extended (E)-2-(2-(thiophen-2-yl)vinyl)thiophene (TVT) were introduced into the polymer backbone. Besides thiophene-based monomers, biselenophene (BS) and (E)-2-(2-(selenophen-2-yl)vinyl)selenophene (SVS) were also copolymerized with the same DSDPP-based monomer. DSDPP-BS and DSDPP-SVS copolymers exhibited higher hole mobilities in thin film transistors (TFTs) than the corresponding BT and TVT analogs. In particular, a TFT having a DSDPP-SVS copolymer-based active layer showed the highest hole mobility of ∼5.23 cm² V^-1 s^-1 and high current on/off ratios of ∼10⁷; this indicates that the π-extended SVS significantly improves charge transport properties.