Multi‐Color Switchable Luminescence in Organic‐Inorganic Metal Halides via Local Polyhedron Regulation Under Light and Temperature Stimuli

Abstract Organic‐inorganic metal halides (OIMHs) with multi‐color switchable luminescence have raised pervasive attention in the field of sensing, optoelectronics, anti‐counterfeiting, information encryption and storage. However, the complexity of soft lattice structures makes it difficult to establish design rules for realizing the luminescence regulation, which greatly hinders their practical applications. Herein, a series of 0D OIMHs are designed, including PA 3 SbCl 6 , PA 6 InCl 9 , PMA 4 InCl 7 , PEA 2 InCl 5 ·H 2 O and PPA 4 InCl 7 . Tunable self‐trapped excitons (STEs) emission from 606 to 678 nm originated from [SbCl n ] 3‐n are realized in these 0D structures by Sb 3+ doping at room temperature. The correlations among structural distortion, bandgap, emission position, and quantum yield are investigated in these 0D Sb 3+ ‐doped OIMHs. The greater distortion of local inorganic polyhedron induces a relative red‐shift emission, while the increased separation distance between local inorganic polyhedron reduces non‐radiative transitions, therefore enhancing quantum yield. Moreover, multi‐emission centers are constructed in Sb 3+ /Bi 3+ ‐doped PMA 4 InCl 7 , achieving green/red and blue/green/red tunable multi‐color switching luminescence under the regulation of excitation wavelength and temperature. Based on the multi‐color luminescence response characteristics, potential application demonstrations in optical anti‐counterfeiting and information encryption are designed. This suggests the application potential of constructing multi‐color switchable luminescence in OIMHs using ns 2 ions, providing a new design perspective for low‐dimensional OIMHs.