Composition Engineering of Organic–Inorganic Perovskites Prepared in Air for Highly Efficient Energy Conversion

The global energy crisis significantly raises the research on renewable energy materials and devices both in academic and industrial community. Besides the electrochemical energy such as batteries, the solar energy is another choice to develop renewable clean energy. During the last ten years, the perovskite solar cells (PSCs) has been a hot research topic and developed fast. However, large-scale production of PSCs is still hindered by the high cost of their fabrication process, because the perovskite films are known to be sensitive to oxygen and water. Therefore, developing a composition engineering in air for PSCs with high solar energy conversion efficiency is urgently required in the field. Herein, it is found that the crystallization and morphology of CH 3 NH 3 PbI 3 (MAPbI 3 ) perovskite films prepared in air are dependent on the processing methods. The perovskite grain size becomes larger when the concentration of CH 3 NH 3 I (MAI) solution was increased from 20 mg/mL to 70 mg/mL, which is beneficial for charge carrier transport and device performance. Thanks to the optimal perovskite fabrication process, the champion PSC has been fabricated in open air and it shows a power conversion efficiency (PCE) of 14.9%. More importantly, the PSC fabricated with our method shows good stability. This work provides an effective composition engineering to fabricate PSCs in air with both high PCE and stability.