Intermediate-Phase-Modified Crystallization for Stable and Efficient CsPbI3 Perovskite Solar Cells

are becoming desirable for their excellent photovoltaic ability and adjustable crystal structure distortion. However, the unsatisfactory crystallization of the perovskite phase is unavoidable and leads to challenges on the road to the development of high-quality CsPbI3 perovskite films. Here, we reported the intermediate-phasepyrrolidine hydroiodide (PI) before the formation of the perovskite phase. The hydrogen bonding, which originates from the interaction between the ???NH in PI and the dimethylammonium iodide (DMAI) from the precursor solution, improved the crystallization conditions and further prompted the transition from the DMAPbI3 phase to CsPbI3 perovskite phase. The application of the IPMC method not only decreased the trap density but also changed the energy alignment for better separation of electron???hole pairs. As a result, the devices based on the PI-CsPbI3 perovskite films reached an efficiency of 18.72% and maintained 85% of their initial PCE after 1000 h of being stored in an ambient environment (???25% RH, 25 ??C). This work stimulates inspiration on how to conveniently fabricate high-quality perovskite films in industry.

Automated summary

This study presents a solution to the unsatisfactory crystallization of CsPbI3 perovskite films, which is a challenge in the development of high-quality perovskite films. The use of pyrrolidine hydroiodide (PI) with hydrogen bonding improves the crystallization conditions and prompts the transition to CsPbI3 perovskite phase. Devices based on PI-CsPbI3 perovskite films demonstrate high efficiency and stability, providing inspiration for the convenient fabrication of high-quality perovskite films in industry.