Direct connection of an amine to oligothiophene to generate push-pull chromophores for organic photovoltaic applications

Through the direct connection of the donor nitrogen atom to oligothiophenes, herein we report three novel, donor materials for evaluation in bulk-heterojunction solar cells. The direct substitution enhances the charge transfer transition, thus improving the light-harvesting ability of the target chromophores. The influence of various terminal acceptor functionalities on the optoelectronic and photovoltaic properties was systematically studied. The target chromophore, T3, bearing oxoindenemalononitrile acceptor unit afforded a power conversion efficiency of 6.12% when paired with the conventional acceptor, PC61BM, a result that is the highest in the current literature for push-pull chromophores.