Photovoltaically top-performing perovskite crystal facets

Discovering the top-performing facets of perovskite crystals holds the secret to highly efficient perovskite solar cells (PSCs). However, the dominated facet properties of perovskite (i.e., (100), (110), (111) facets) remain elusive. Here, we demonstrate that exquisite control of the perovskite film formation enables the formation of perovskite polyhedral single crystals with well-defined facets. It is found that facets with variant densities and symmetries of atoms govern the perovskite surface chemical and electronic environment and generate significant effects on the photovoltaic performance. Carrier mobility and photocurrent of the (100) crystal facet are almost comparable with those of the (111) facets, which are much higher than those of the (110) one. With the single-crystal-assembled perovskite thin film, the PSC achieves a quasi-steady-state (QSS) efficiency of 24.64% with improved stability to light. Our work provides a deep understanding of the optoelectronic properties of halide perovskite facets.