Chemical Composition Regulation for Tuning the Luminescent Properties of Organic–Inorganic Metal Halides

Organic–inorganic metal halides (OIMHs) exhibiting superior optoelectronic properties have shown broad applications in sensing, photovoltaic devices, information storage, and biological imaging. Compared with pure inorganic or pure organic materials, OIMHs are distinguished by their hybrid feature, with processability of organic components and robustness of inorganic units, as well as plentiful luminescent sources derived from organic ligands, self‐trapped excitons (STEs) of inorganic lattices, or the energy transfer between organic and inorganic species. Thereinto, chemical composition tunability of organic component, metal ions, and halogen provides multiple adjustable sites to tailor their structures and physicochemical properties. However, how to realizing effective and tunable luminescence in OIMHs for desired applications through rational chemical composition regulation has become a challenge. In this review, starting from the structurally tunable sites of OIMHs, the feasible methods for regulating the luminescent properties of OIMHs are summarized, which include the change of organic components, tunable dimensionality and configurations of inorganic species, heterometal inorganic units, as well as the systematic multisite fine‐tuning based on a specific matrix. Finally, the challenges to synthesize OIMHs with promising luminescence performance through chemical composition regulation are discussed.