Atmosphere dependent gas-solid reaction for high-quality MAPbBr3 perovskite solar cells

Abstract It is imperative to develop a high-quality hybrid perovskite film with large crystallinity and smooth morphology for high-performance stable perovskite solar cells. Herein, vapor assisted crystallization method was used to fabricate crystalline CH3NH3PbBr3 (MAPbBr3) films through the precisely controlled gas-solid reaction. The effect of different atmosphere condition (N2, vacuum and air conditions) on the final MAPbBr3 films was investigated. It is found that the N2 atmosphere is in favor for obtaining uniform perovskite film (MAPbBr3-N2) which exhibits good crystallization, strong absorption and few defects due to the slow crystallization reaction. In this way, the MAPbBr3-N2-based device shows an open-circuit voltage (Voc) of 1.20 V and power conversion efficiency (PCE) of 4.88%, much higher than the devices fabricated in the vacuum state. Based on this atmosphere, a champion PCE of 7.30% with a Voc of 1.384 V can be achieved by introducing mesoporous TiO2 layer. Our results could provide valuable information for the fabrication of high-quality perovskite films for photoelectric device.