Highly Reproducible and Efficient Perovskite Solar Cells with Extraordinary Stability from Robust CH₃NH₃PbI₃: Towards Large‐Area Devices

Abstract Organic–inorganic hybrid solar cells based on air‐stable CH 3 NH 3 PbI 3 perovskites are reported. The perovskite layer was synthesized by CH 3 NH 3 I (methylammonium iodide, MAI) vapor‐assisted growth on a PbI 2 layer. This process is optimized to achieve uniform, pore‐free, compact, and highly stable crystalline perovskite layers. The extraordinary stability of this pristine perovskite layer for about 3 months in air was compared with films obtained by other crystallization methods using X‐ray diffraction (XRD) studies. The effect of the perovskite layer thickness on the photo‐conversion efficiency (PCE) and external quantum efficiency are evaluated. The solar cell optimization reveals that the 370 nm thick perovskite layer delivers highly reproducible devices with a PCE value of 14.8 % (average 13.4 %) and negligible parameter fluctuation as well as high stability (of more than one month) with negligible loss. Additionally, we demonstrate that this MAI vapor‐assisted method is suitable to fabricate devices having an area of 1.05 cm 2 and device efficiency of 8.7 %.