Benzotrithiophene-Based Conjugated Polymer and Application in Organic Photovoltaic

A conjugated polymer (PBTT) based on 4,3’-didodecyl-2,2′-bithiophene (M1) and 2,8-dibromo-5-(2-hexyldecanoyl) benzotrithiophene (M2) were synthesized by a Stille coupling reaction in the presence of tris(dibenzylidene-acetone) dipalladium (Pd2(dba)3) as a catalyst and tri(o-tolyl)phosph-ine (P(o-tol)3) as a ligand. The polymer was characterized by thermal analysis, as well as optical spectroscopy and electrochemical testing. Polymer PBTT showed excellent thermal stability, and possessed deep highest occupied molecular orbital (HOMO) level. Polymer film had a maximal absorption peak at 469 nm with the optical bandgap of about 2.10 eV. The photovoltaic devices were fabricated based on PBTT and ［6,6］-phenyl-C61-butyric acid methyl (PC61BM), and exhibited power conversion efficiency of 0.43% with an open-circuit voltage as high as 1.00 V under AM 1.5 G illumination at 100 mW/cm2 with a solar simulator.