Nucleation Modification in Two‐Step Slot‐Die Coating Toward Efficient Large Scale Perovskite/Silicon Tandems Based on Commercial Silicon Cells

Abstract Vapor‐solution two‐step deposition is recognized as a promising method to fabricate monolithic perovskite/silicon tandem solar cells (TSCs) on commercial silicon cell substrates with fully textured surfaces. Although a certified power conversion efficiency (PCE) of 31.3% is recorded for small size perovskite/silicon TSCs, scaling up from spin‐coating used for small sizes to the slot‐die for large areas has become the main challenge for its further mass production due to the residual PbI 2 and increased internal voids in perovskite (PVK) films. In this study, sodium 2,5‐difluorobenzoate (2,5‐NaDPA) is utilized to reduce nucleation energy barrier difference at various convex angles on PbI 2 layer, delaying the growth of perovskite crystals, and effectively promoting the grain size of perovskites, which is particularly favorable for perovskites deposited on commercial textured Si substrates. Eventually, the voids of large area PVK films are greatly restrained. A high efficiency of 28.28% is obtained from a fully textured perovskite/silicon tandem device prepared in ambient condition with an effective area of 19.9 cm 2 . This work paves a new method for commercial production of large area perovskite/silicon TSCs.