Phenylenevinylene copolymers of dihexylthienylbenzothiadiazole and triphenylamine or tetraphenylbenzidine: synthesis, characterization and photovoltaic properties

Three novel low-band gap phenylenevinylene copolymers (P1, P2, and P3), containing dihexylthienylbenzothiadiazole (DTBT) and triphenylamine (TPA) or tetraphenylbenzidine (TPD) were synthesized via the Wittig–Horner reaction. The effects of TPA and TPD on the thermal, optical, electrochemical and photovoltaic properties were investigated. The UV–Vis spectrum of P3, which contains TPD in the polymer backbone, exhibits a broader and stronger absorption in the film than those of P1 and P2. The bulk heterojunction solar cells were fabricated with the as-synthesized polymers as the donors and [6,6]-phenyl-C61-butyric acid methyl ester as the acceptor in a 1:4 weight ratio. The device based on P3 exhibits the maximum power conversion efficiency of 1.11 % under simulated AM 1.5 G solar irradiation (100 mW/cm2).