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Low‐dimensional metal halides (LDMHs) represent a promising class of materials in various luminescent applications because of their self‐trapped exciton (STE) emissions with unique properties such as broad luminescence spectra, large Stokes shift, and high color rendition. LDMHs at the molecular level can be constructed, including 2D layers, 1D chains, and 0D clusters assembled by polyhedra units, all of which exhibit significantly different luminescence properties from 3D MHs. The dimensional regulation of LDMHs has been explored for years, including the choice of organic cations, modulating electron‐phonon coupling effect, and adding external temperature and pressure. Herein, this review discusses the synergy between structural engineering and solvent effects for LDMHs, including the emission mechanisms for LDMHs and the roles solvent molecules play in regulating the dimensions. In addition, challenges and opportunities for LDMHs are discussed to shed light on the future development of novel materials with multifunctional optical properties suitable for practical applications. [ABSTRACT FROM AUTHOR]

Low‐dimensional lead‐based metal halide perovskites (MHPs) have many exceptional photoelectric capabilities thanks to the 6 s2 electron structure of lead ion (Pb2+). Pb2+′s toxicity, however, has prevented its widespread development and use. Finding ions in the valence layer that have a comparable electrical structure thus makes sense as Pb2+ replacements. In this work, all inorganic zero‐dimensional (0D) Cs3BiCl6 single crystal was synthesized by the anti‐solvent crystallization method. There is no obvious photoluminescence (PL) phenomenon for Cs3BiCl6 at room temperature (RT). It is found that the extremely strong exciton‐phonon interaction leads to seriously non‐radiative recombination. After doping with Sb3+, Cs3BiCl6: Sb achieved broadband emission with a significant Stokes shift, the photoluminescence quantum yield (PLQY) up to 15.85 %, which has a microsecond PL decay lifetime and excellent environmental stability. Systematic spectroscopic characterizations unveil the PL mechanism of Cs3BiCl6: Sb is self‐trapped excitons (STEs) emission, and theoretical calculation revealed the indirect bandgap properties of Cs3BiCl6 and Cs3BiCl6: Sb. [ABSTRACT FROM AUTHOR]

Zero‐dimensional metal halides have attracted much attention due to their attractive photoelectric properties. Here, we propose a new strategy of synthesizing metal halides crystals by recrystallization in water. The as‐synthesized Cs2InCl5(H2O)‐orange crystals are dissolved and recrystallized in water (Cs2InCl5(H2O)‐blue), with its photoluminescence (PL) changing from orange to blue, both of which are derived from self‐trapping excitons (STEs). The time‐resolved photoluminescence (TRPL) spectrum of Cs2InCl5(H2O)‐blue shows that it has an ultralong lifetime up to milliseconds (τ=52.98 ms), which is expected to be applied in biological sensors. The photoluminescence quantum yield (PLQY) increases from 2.25% to 11.61% in the self‐assembly process. By using a post‐doping method, the PL of crystals turns into red when we introduce Mn2+ as dopant while there is no obvious change upon using a traditional solvent‐thermal method. Recrystallization in water and post‐doping provide a new perspective for the synthesis and doping of metal halides. [ABSTRACT FROM AUTHOR]

Low‐dimensional lead‐based metal halide perovskites (MHPs) have many exceptional photoelectric capabilities thanks to the 6 s2 electron structure of lead ion (Pb2+). Pb2+′s toxicity, however, has prevented its widespread development and use. Finding ions in the valence layer that have a comparable electrical structure thus makes sense as Pb2+ replacements. In this work, all inorganic zero‐dimensional (0D) Cs3BiCl6 single crystal was synthesized by the anti‐solvent crystallization method. There is no obvious photoluminescence (PL) phenomenon for Cs3BiCl6 at room temperature (RT). It is found that the extremely strong exciton‐phonon interaction leads to seriously non‐radiative recombination. After doping with Sb3+, Cs3BiCl6: Sb achieved broadband emission with a significant Stokes shift, the photoluminescence quantum yield (PLQY) up to 15.85 %, which has a microsecond PL decay lifetime and excellent environmental stability. Systematic spectroscopic characterizations unveil the PL mechanism of Cs3BiCl6: Sb is self‐trapped excitons (STEs) emission, and theoretical calculation revealed the indirect bandgap properties of Cs3BiCl6 and Cs3BiCl6: Sb. [ABSTRACT FROM AUTHOR]