Advances of batch-variation control for photovoltaic polymers

The state-of-the-art bulk-heterojunction (BHJ)-type organic solar cells (OSCs) have achieved over 19% power conversion efficiency (PCE), encouraging the development of the fabrication of massive OSC modules and commercial available photovoltaic devices. However, numerous studies have showed that the reliability of the polular photovoltaic polymers on photovoltaic performance is limited mostly due to the inferior batch-to-batch reproducibility, which limit the potential applications of OSCs. To systematically understand the origin of polymer batch-to-batch variations, and seek feasible approach to batch-to-batch control, in this review, recent progress in polymer batch-to-batch reproducibility research on OSCs in the past few decades were summarized. Finally, the empirical regularities and the major challenges for lowing batch-to-batch variations of polymers are illustrated.