High performance perovskites solar cells by hybrid perovskites co-crystallized with poly(ethylene oxide)

Hybrid perovskite materials have emerged as attractive alternatives for cost-effective solar cells in the past ten years. However, achieving hysteresis-free, stable and efficient solution-processed perovskites solar cells has remained as a significant fundamental challenge. In this study, we report a strategy that utilizes poly (ethylene oxide) to sequester the counter ions in the perovskite lattices to suppress the formation of point defects, reduce the migration of ions/vacancy and to facilitate crystal growth in a more thermodynamically preferred orientation. Systematical investigations indicate that poly (ethylene oxide) indeed form hydrogen bonds with perovskite, which reduces the formation of kinetically-driven point defects, minimize charge carrier recombination and sharpen the density of states distribution. As a result, un-encapsulated solution-processed perovskite solar cells exhibit stabilized power conversion efficiency with hysteresis-free characteristics and significantly improved ambient shelf- and thermal-stability at relative high humidity, in comparison to the reference devices that exhibit unstable power conversion efficiency with dramatically higher hysteresis factor and poorer device lifetime. Our studies demonstrate that development of hybrid perovskite materials co-crystallized with polymers is an efficient approach towards high performance perovskite solar cells.