Facet engineering in perovskite solar cells: Facet properties, crystallization regulation, and device performance

Crystal facet engineering has emerged as an effective strategy to regulate the performance and stability of perovskite solar cells. Different facets exhibit distinct atomic terminations, defect chemistries, ion migration pathways, and thermal transport behaviors, producing anisotropy in photoelectric characteristics and stability. This review systematically summarizes recent progress in understanding the facet-dependent properties of perovskite, with emphasis on common facets ((100), (110), (111)) and the emerging high-miller-index facet (211). We further discuss representative strategies for controlling facet-preferred growth, including additive and solvent engineering, precursor and template regulation, and interface-induced orientation control. Furthermore, facet-enabled device optimization methods are highlighted, such as facet-selective passivation, facet heterojunctions, and strain relief through facet complementarity. These insights establish facet engineering as a key design axis for efficient and stable perovskite photovoltaics.