Building Block for Organic Photovoltaic Cell Polymers

2,1,3-Benzothiadiazole is a well-known electron-deficient molecule, which can be conjugated with an electron-rich molecule to form co-polymers with small energy band gaps. Recently, several different co-polymers bearing the benzothiadiazole moiety have been synthesized for organic photovoltaic devices. For instance, Kim et al. have reported the synthesis of the co-polymer, which is generated from an electron-rich phenanthrene moiety and an electron-deficient 2,1,3-benzothiadiazole moiety, using 1 as a starting material. According to their results, the bulk heterojunction solar cell composed of this co-polymer and PC₇₁BM gives a power conversion efficiency of 1.12%.