Pressure-Triggered Blue Emission of Zero-Dimensional Organic Bismuth Bromide Perovskite

Understanding the structure-property relationships in Zero-dimensional (0D) organic-inorganic metal halide perovskites (OMHPs) is essential for their use in optoelectronic applications. Moreover, increasing the emission intensity, particularly for blue emission, is considerably a challenge. Here, intriguing pressure-induced emission (PIE) is successfully achieved from an initially nonluminous 0D OMHP [(C₆H₁₁NH₃)₄BiBr₆]Br·CH₃CN (Cy ) upon compression. The emission intensity increases significantly, even reaching high-efficiency blue luminescence, as the external pressure is increased to 4.9 GPa. Analyses of the in situ high-pressure experiments and first-principle calculations indicate that the observed PIE can be attributed to the enhanced exciton binding energy associated with [BiBr₆]^3- octahedron distortion under pressure. This study of Cy sheds light on the relationship between the structure and optical properties of OMHPs. The results may improve potential applications of such materials in the fields of pressure sensing and trademark security.