Comprehending Perovskite Film Formation Dynamics in Moist Conditions and Their Influence on Photovoltaic Device Performance

Fabricating perovskite solar cells under ambient conditions is an essential step toward achieving mass production. While there is a wealth of knowledge regarding perovskite film formation in inert environments, research in moist environments, despite its practical significance, remains notably limited. Through the application of a diverse range of characterization techniques, including our custom-built, in situ photoluminescence (PL) measurement, we gain a comprehensive understanding of the entire process of perovskite film formation under both dry and moist conditions. Our results underscore that moisture disrupts the equilibrium between crystal growth and dissolution, fundamentally altering the film formation dynamics and, hence, the ultimate device performance. Remarkably, at an optimized humidity level of 35%, we achieve a more precise and controlled crystal growth compared to the dry condition, resulting in a reduction of defects and ultimately yielding an efficiency of 23.79%. These findings provide valuable insights into the control of perovskite crystallization under manufacturing-relevant environmental conditions.