Composition Engineering of Perovskite Single Crystals for High‐Performance Optoelectronics

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 ABX3 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. The excellent photoelectric performance, simple preparation process, and potentially extremely low preparation cost of halide perovskites not only attract the attention of a large number of researchers but also obtain the favor from industry. This review summarizes the latest progress of perovskite for X‐ray detection in the past 10 years, identifies the challenges, and suggests the main research directions in future.