Intense Broadband Emission in the Unconventional 3D Hybrid Metal Halide via High-Pressure Engineering

Developing hybrid metal halides with self-trapped exciton (STE) emission is a powerful and promising approach to achieve single-component phosphors for wide-color-gamut display and illumination. Nevertheless, it is difficult to generate STEs and broadband emission in the classical and widely used 3D systems, owing to the great structural connectivity of metal-halogen networks. Here, high pressure is implemented to achieve dual emission and dramatical emission enhancement in 3D metal halide of [Pb₃ Br₄ ][O₂ C(CH₂ )₂ CO₂ ]. The pressure-induced new emission is ascribed to the radiation recombination of STEs from the Pb₂ Br₂ O₂ tetrahedra with the promoted distortion through the isostructural phase transition. Furthermore, the wide range of emission chromaticity can be regulated by controlling the distortion order of different polyhedral units upon compression. This work not only constructs the relationship between structure and optical behavior of [Pb₃ Br₄ ][O₂ C(CH₂ )₂ CO₂ ], but also provides new strategies for optimizing broadband emission toward potential applications in solid-state lighting.