Synthesis and Photovoltaic Properties of New Multifused Anthradithiophene-Based Narrow-Bandgap D-A Copolymers

摘要

Three structurally novel donor-acceptor copolymers are synthesized and fully characterized using an anthradithiophene (ADT) derivative as the donor block. All of them exhibit broad absorption ranges and moderate hole and electron mobilities. The multifused ADT donor block makes them exhibit lower highest occupied molecular orbital (HOMO) energy levels than many reported benzodithiophene-based polymers. Copolymer blends with [6,6]-phenyl C71 butyric acid methyl ester (PC_(71) BM) as active layers are used to fabricate polymer solar cells (PSCs) and a variety of post-treatment methods are employed to optimize the device performance. The conventional and inverted confi guration devices are prepared to evaluate the photovoltaic properties. A maximum power conversion effi ciency of 1.66% is achieved for the inverted-confi guration device. The improved effi ciency is caused by the close energy alignment between the work function of MoO_3 and the HOMO energy levels of the copolymers, facilitating better charge transport and increased shortcircuit current density (J_(sc)) with the inverted devices.