Pseudohalide-Assisted Growth of Oriented Large Grains for High-Performance and Stable2D Perovskite Solar Cells

Defects from grains and boundaries and the random phasedistribution of 2D perovskitefilms generally cause nonradiativerecombination and a reduction in carrier transport and stability. Herein,wefind that pseudohalides can promote the growth of oriented large-grained 2D perovskitefilms. It is shown that pseudohalide additives caninduce the aggregation and the assembly of 2D perovskites, effectivelyfacilitate the assembly of random low-nphases into pure high-nphases,and enlarge the corresponding grain sizes offilms. Concurrently, the phasedistribution, crystalline quality, and carrier transport of perovskitefilmsare also improved. As a result, the pseudohalide-optimized perovskite solarcells achieve remarkably improved PCEs of 18.72% and a negligiblehysteresis. Importantly, the unencapsulated devices retain 100% of theinitial efficiencies at persistent heating at 55 degrees C for 1180 h. After they werekept operating under the maximum power point (MPP) with continuous light illumination for about 1200 h, the devices showed only 13.3% efficiency degradation

Automated summary

This study finds that pseudohalides can promote the growth of oriented large-grained 2D perovskite films, improve their phase distribution, crystalline quality, and carrier transport, resulting in significantly improved efficiency and thermal stability of perovskite solar cells.