Conjugated rod-coil and rod-rod block copolymers for photovoltaic applications

Conjugated polymer-based bulk heterojunction (BHJ) solar cells are widely recognized as a promising alternative to their inorganic counterparts for achieving low-cost, roll-to-roll production of large-area flexible lightweight photovoltaic devices. Current research in designing new polymers and optimizing device architectures has been devoted to improving the film morphology, photovoltaic performance and stability of polymer BHJ solar cells. Conjugated block copolymers (BCPs), including rod-coil and rod-rod BCPs, exhibit excellent flexibility for tuning the band gap of semiconductor polymers, regulating the molecular organization of donor (and/or acceptor) units, templating the film morphology of active layers, and achieving well-defined BHJ architectures. In this Feature Article, we summarize the recent developments over the past five years in the synthesis, self-assembly, and utilization of conjugated rod-coil and all-conjugated rod-rod BCPs for solar energy conversion, highlight the correlation between the microphase-separated morphology and photovoltaic properties in conjugated BCPs, and finally provide an outlook on the future of BCP-based photovoltaic devices.