A series of polymers based on 8,8 0 -biindeno[2,1b]thiophenylidene for use in photovoltaic devices and fieldeffect transistors are reported. These structurally twisted olefins are effective building blocks for preparation of low bandgap polymers with optical bandgaps of 1.2-1.5 eV. Device performance, such as V oc and J sc , in solar cell devices could be successfully modulated by incorporation of a variety of comonomers. Ambipolar properties in field-effect transistors using Au electro-des were also studied, with PtBTPDPP exhibiting balanced charge transport properties with hole and electron mobilities of 0.09 and 0.12 cm 2 ÁV 21 Ás 21 , respectively. V C 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 889-899