Perovskite Solar Cells with Enhanced Fill Factors Using Polymer-Capped Solvent Annealing
Jaemin Kong, Hanyu Wang, Jason A. Röhr, Zachary S. Fishman, Yuanyuan Zhou, Ming‐Xing Li, Mircea Cotlet, Geunjin Kim, Christopher Karpovich, Francisco Antônio, Nitin P. Padture, André D. Taylor
Abstract
Despite huge improvements in power conversion efficiencies of perovskite solar cells, the technology is still limited by fill factors at around 80%. Here, we report perovskite solar cells having exceptionally high fill factors of 85% and enhanced open-circuit voltage without sacrificing short-circuit current through a polymer-capped solvent-annealing process assisted by a hot air blower. During the solvent-annealing, the perovskite surface flattens and the perovskite grains agglomerate into micrometer-sized clusters having enlarged α-phase crystallites, while the δ-phase simultaneously disappears. The optimized structure reduces energetic disorder and trap-assisted recombination in the perovskite layer, resulting in an enhanced efficiency from 18.2% to 19.8% and improved device lifetime. Our results provide a pathway to increase the device efficiency and stability of perovskite solar cells, and have the potential to stimulate research on scalable poly-crystal perovskite layer fabrication in optoelectronic devices.