High-performance vinyl-flanked diketopyrrolopyrrole–selenophene polymer semiconductors with branched, linear and cyclic alkyl side chains

Abstract

Vinyl-containing conjugated polymers exhibiting extended conjugated skeletons with long-wavelength absorption and high carrier mobility have been widely investigated as polymer semiconductors. However, a new vinyl-flanked diketopyrrolopyrrole (DPP) unit with the vinyl groups directly connecting at 3,6-positions of the DPP core has rarely received attention. Herein, we reported three semiconducting polymers (PDPPTSe, PDPPTSe12 and PDPPTSeCyH in Scheme 1c) containing vinyl-flanked DPP and selenophene units with branched, linear or cyclic alkyl side chains. PDPPTSe12 with a linear side chain exhibits a high hole mobility of 6.76 cm² V⁻¹ s⁻¹, which can be attributed to the high crystallinity of its thin film, tight π–π stacking and better interchain packing orientation in comparison with PDPPTSe. In contrast, the hole mobility of PDPPTSeCyH with a cyclohexyl side chain is only 0.83 cm² V⁻¹ s⁻¹ because of the large π–π distance, low solubility and low crystallinity. This work reveals that the vinyl-flanked DPP unit is a useful building block to obtain high-mobility polymer semiconductors through side-chain modifications.