Zero‐Dimensional Organic–Inorganic Hybrid Metal Halides as Luminescent Materials: A Review From the Perspective of Molecular Level

Owing to their structural tunability, soluble processability, and excellent photophysical properties, organic–inorganic hybrid metal halides (OIHMHs) have attracted significant attention as optically functional materials. Among this broad family of materials, the majority of zero‐dimensional (0D) OIHMHs are characterized by spatially isolated metal‐halide polyhedra or finite clusters separated by organic components. The physicochemical properties of 0D OIHMHs are highly structure‐dependent, and molecular design plays a key role in determining their optical behavior. However, systematic investigations of the structure‐luminescence relationship in 0D OIHMHs remain in their infancy. In this review, we start with the structural construction of 0D OIHMHs. Next, recent progress in the molecular design of 0D OIHMHs is summarized, including strategies such as polyhedral architecture engineering, elemental composition and substitution engineering, donor–acceptor/host‐guest engineering and multi‐emissive‐center integration and coupling engineering. These molecular design principles have extended the luminescence behavior of 0D OIHMHs, paving the way for potential commercial applications in scintillators, light‐emitting diodes (LEDs) and so on. Finally, we present future research opportunities in designing 0D OIHMHs. This review aims to guide the future development of 0D OIHMHs materials with tunable and enhanced functionalities.