Composition Engineering of Perovskite Single Crystals for High‐Performance Optoelectronics

Abstract Composition engineering, with its advantages to effectively tune semiconductor properties by regulating chemical stoichiometry, is a proven strategy to boost the efficiency and stability of ABX 3 perovskite photoelectronic devices. Compared with its counterpart polycrystalline perovskite film, single crystalline is the ideal model for exploring its fundamental scientific issues. In this review, a critical overview of recent advances of the growth strategies, properties, and functional applications of multicomponent perovskite single crystals (SCs) is presented. First, the underlying advantages of composition engineering of perovskite SCs are discussed and then the different composition tuning strategies, including A‐site, B‐site, X‐site, and simultaneous A‐ and X‐site engineering, are systematically summarized. Subsequently, the benefits of composition engineering are highlighted for optimizing photovoltaic and photoelectronic devices. Lastly, controversies and remaining challenges for the development of composition engineering of perovskite SCs are discussed and a brief perspective regarding further investigation in this field is provided.