Unlocking the Potential of Inverted Perovskite Solar Cells by Mastering Interface Wettability

Inverted perovskite solar cells (IPSCs) are gaining commercial traction due to their rising power conversion efficiency, simple manufacturing, reliable operation, and compatibility with various perovskite-based tandem devices. Yet, their performance is hindered by the quality of perovskite films, where interface wettability control is crucial in solution method film formation process preparation such as spin coating, spray coating, and trowel coating. Here, we focus on the bottom HTL (hole transport layer)─perovskite interface in p-i-n PSCs, reviewing how interface wettability impacts perovskite crystallization, charge transport/recombination, and device stability in inverted PSCs. The potential for optimizing device performance after decoding the wettability regulation mechanism was suggested. Finally, the mechanism of how wettability enhances the quality of perovskite films and device performance was analyzed though a large amount of articles summarized. The methods for regulating wettability were elaborated from three aspects: interface engineering, precursor solution engineering, and the post-treatment process. We also provide future research directions in interface wettability engineering for large-scale production and commercialization, such as developing low-cost processes and changing the thermal physical properties of the solution to adjust the interface wettability. This review offers theoretical guidance for understanding the relationship between interfacial wettability and device performance and envisions the potential path for the industrial application of inverted PSCs.