Organic Photovoltaic Cells Based on Molecular Donor-Acceptor Heterojunctions

Small molecule based organic photovoltaic cells have attracted considerable interest as a potential solution for low-cost solar energy conversion in the near future. In this review, we first discuss the operation, advantages, and limitations of three different molecular donor-acceptor heterojunction structures. We then discuss the phase separation in molecule donor-acceptor mixtures and its impact on the photovoltaic performance. Methods to achieve bulk heterojunctions with controlled nanoscale geometry are also reviewed. Finally, we provide an outlook on major remaining challenges to the further development of this photovoltaic technology.