Improvement of optoelectronic and photovoltaic properties through the insertion of a naphthalenediimide unit in donor–acceptor oligothiophenes

Improvements to the optoelectronic and photovoltaic properties of 2-((5′-(4-(diphenylamino)phenyl)-[2,2′-bithiophen]-5-yl)methylene)malononitrile ( R1 ; a donor–acceptor small molecular oligothiophene) are reported through the insertion of planar, conjugated napthalenediimide moiety. The novel donor material was successfully synthesized and exhibited a power conversion efficiency of 3.01% under AM 1.5 G irradiation (100 mW cm −2 ) when tested in solution-processable bulk heterojunction solar cells with PC 61 BM as an acceptor material.