Facet Engineering for Stable, Efficient Perovskite Solar Cells

Facet engineering is an important strategy for tuning the physical, chemical, and electronic properties of a crystal surface, and it also provides an effective route to improve the device performance in many fields. Complex crystal structures with rough morphologies have been observed for most of the hybrid perovskite thin films. Thus, it is speculated whether high-quality crystals with tunable facets can be formed on a perovskite thin film and how the facet properties can influence the device performance. More importantly, the high-quality crystals and tunable facets are also effective strategies to further improve the efficiency and stability of perovskite devices. This perspective provides the challenges to achieving high-quality crystals with tunable facets and discusses the crystal shape, facet properties, and several prospects of facet engineering on perovskite thin films.