Control of vertical distribution of thiophene-based copolymers containing 4,7-Dithien-2-yl-benzo[C][1,2,5]thiadiazole and 3,6-Dithien-2-yl-pyrrolo[3,4-C]pyrrole-1,4(2H,5H)-dione as Side Groups for Photovoltaics

摘要: Four new D—A type copolymers with 2D-conjugated side-chain identified PfToBT, PbToBT, PfTDPP and PbTDPP, containing two acceptors 4,7-dithien-2-yl-benzo[c][1,2,5]thiadiazole (DTBT), diketopyrrolopyrrole (DPP) linked by thiophene donors, are obtained using Pd-catalyzed Stille-coupling reaction. These polymers show a broad visible-near-infrared absorption band (Eg = 1.79–1.66 eV) possess relatively low-lying HOMO level at −5.34 to −5.12 eV. All the polymer:PC70BM blend films showed edge-on structure have similar dπ-spacing values. According of conjugated side-chain, vertical distributions polymer chains PC70BM within BHJ (bulk heterojunction) were different. When DPP used as an acceptor, side coexisted in same position. The film prepared from PbToBT had discontinuous network between PC70BM, whereas PbTDPP formed continuous evenly distributed them. This optimized morphology promotes hole transport along respective pathways fullerenes direction, leading high JSC. shows PCE up 2.9% (Jsc 9.4 mA/cm2, Voc 0.68 V, FF 0.44). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Chem. 2016, 54, 2746–2759