全无机金属卤化物灵活多变的结构及优异的发光性能使其在固态光电子领域显示出重要的应用前景。本研究采用异价阳离子取代策略，用三价锑离子部分取代CsCdCl3中的二价镉离子，促进自陷激子的产生，使CsCdCl3∶Sb3+产生了明亮的宽带绿色发光，中心波长为530 nm。机理研究结果表明，CsCdCl3∶Sb3+ 中相邻SbCl6八面体被孤立，形成了低维电子构型，促进了Sb3+ 局域化，实现了量子效率最高为95.5%的高效发光。此外，尽管CsCdCl3和RbCdCl3均属于ACdCl3(A为碱金属家族)，但它们的晶体结构明显不同。RbCdCl3属于正交晶系，空间群为Pnma；CsCdCl3属于六方晶系，空间群为P63/mmc。CsCdCl3的结构对称性大于RbCdCl3，其晶体结构偏离立方相的扭曲程度比RbCdCl3小，导致CsCdCl3∶Sb3+比RbCdCl3∶Sb3+有较小的斯托克斯位移，并造成发射光谱的蓝移。本工作不仅为异价阳离子取代设计新的发光材料提供了方法，而且为通过晶体结构对称调控金属卤化物的发光性能提供了思路。

All-inorganic metal halides have shown significant applications in solid-state optoelectronics because of their flexible structures and impressive fluorescence emissions. In this study, a heterovalent cation substitution strategy was used to partially replace the divalent cadmium ions in CsCdCl3 with trivalent antimony ions to promote the production of self-trapped excitons, resulting in a bright broadband green photoluminescence of CsCdCl3∶Sb3+ with a central wavelength of 530 nm. Mechanism researches results show that the adjacent SbCl6 octahedra in CsCdCl3∶Sb3+ are isolated, forming a low-dimensional electronic configuration that promotes Sb3+ localization and achieves efficient photoluminescence with a quantum efficiency of up to 95.5%. Furthermore, although both CsCdCl3 and RbCdCl3 belong to ACdCl3 (A is an alkali metal family), they have distinctly different crystal structures. RbCdCl3 crystallizes in the orthorhombic crystal system with space group of Pnma; while CsCdCl3 crystallizes in the hexagonal phase crystal system with space group of P63/mmc. The structural symmetry of CsCdCl3 is higher than that of RbCdCl3, indicating that its crystal structure is less distorted away from the cubic phase than that of RbCdCl3, resulting in a smaller Stokes shift and corresponding blue shift of the emission spectrum in CsCdCl3∶Sb3+ than in RbCdCl3∶Sb3+. This work not only provides a method for designing new photoluminescence materials by heterovalent cation substitution but also paves an avenue for modulating the luminescent properties of metal halides through crystal structure symmetry.