Vinylene-bridged 5-alkoxy-6-fluorobenzo[c][1,2,5]thiadiazole (FOBTzE) as a novel acceptor unit and its copolymer PFOE4T were designed and synthesized. The incorporation of an electron-donating alkoxy group instead of a fluorine atom prevented strong aggregation tendency and changed the molecular orientation of the polymers from edge-on to bimodal orientation, which was expected to provide uniform thin-film with PC61BM and promoted carrier transport. However, since PFOE4T has still strong aggregation ability and low solubility, the PFOE4T/PC61BM blended film formed a large phase separation, resulting in a power conversion efficiency of only 4.52%.
- Hiroki Mori
- Yuya Asanuma
- Yasushi Nishihara
