Acceleration effect of chlorine in the gas-phase growth process of CH3NH3PbI3(Cl) films for efficient perovskite solar cells

Abstract

To date, the fundamental question still remains regarding the role of chlorine (Cl) in the gas-phase growth process of CH₃NH₃PbI₃(Cl) perovskites. Herein, we report an NH₄Cl-assisted chemical vapor deposition (CVD) method for fabricating efficient perovskite solar cells (PSCs). It was found that the elaborately introduced Cl has an obvious acceleration influence on the formation of perovskites through forming intermediate phase CH₃NH₃PbCl₃ and volatile NH₃ and HI, which may effectively reduce the reaction time from 2–4 hours to 50 minutes, and drastically decrease the reaction temperature from above 150 °C to 120 °C. As such, the average power conversion efficiency (PCE) of perovskites was significantly enhanced from 10.86% to 12.2%, and an impressive 13.3% champion efficiency was successfully achieved in this study. Therefore, our finding readily overcame the bottleneck of common CVD approaches and was also helpful to understand the PbI₂–CH₃NH₃PbCl₃–CH₃NH₃PbI₃ gas-phase growth kinetics of perovskites, which shows high potential for application in flexible PV devices.