Engineered Vacuum-Incorporated Rubidium Iodide for CH₃NH₃PbI₃ Perovskite Solar Cell Stability

High Resolution Image Download MS PowerPoint Slide A cation engineering strategy is crucial for optimizing CH 3 NH 3 PbI 3 (MAPbI 3 )-based perovskite solar cells (PSCs) and for controlling their interfacial properties to achieve high stability. In this study, we used vacuum-deposited rubidium iodide (RbI) and induced incorporation into solution-processed MAPbI 3 to obtain high-quality dense perovskite films for highly stable PSCs. An optimized 10 nm film of RbI was deposited and incorporated on both interfaces of the MAPbI 3 film, at the interfaces with the electron transport layer (ETL) and hole transport layer (HTL), forming the structure RbI–MAPbI 3 –RbI. This significantly enhanced the host MAPbI 3 morphology, grain size, and crystallinity. PSCs with RbI–MAPbI 3 –RbI as perovskite film exhibited power conversion efficiencies (PCEs) as high as 17.50%, whereas the pristine MAPbI 3 devices reached 14.81%. The RbI–MAPbI 3 –RbI-based devices (non-encapsulated) retained over 95% of their initial PCE after 2300 h in ambient air under a relative humidity of 25%–35%. RbI incorporation improves the hydrophobicity of the perovskite film, leading to an improvement in moisture stability. The present work demonstrates the potential for developing highly stable perovskite devices through precise RbI incorporation.