Recent progress in solution-processed flexible organic photovoltaics

The certified power conversion efficiency (PCE) of organic photovoltaics (OPV) fabricated in laboratories has improved dramatically to over 19% owing to the rapid development of narrow-bandgap small-molecule acceptors and wide bandgap polymer donor materials. The next pivotal question is how to translate small-area laboratory devices into large-scale commercial applications. This requires the OPV to be solution-processed and flexible to satisfy the requirements of high-throughput and large-scale production such as roll-to-roll printing. This review summarizes and analyzes recent progress in solution-processed flexible OPV. After a detailed discussion from the perspective of the behavior of the narrow bandgap small-molecule acceptor and wide bandgap polymer donor active layer in solution-processed flexible devices, the existing challenges and future directions are discussed.