Achieving bright white-light emission in all-inorganic undoped copper(I) halides via pressure-induced multiple self-trapped states

All-inorganic, undoped copper(I)-based halides are promising candidates for solid-state lighting applications owing to their low toxicity and high energy efficiency. Nevertheless, achieving highly efficient white-light emission from this class of materials remains a significant challenge. In this study, we employ a high-pressure physical modulation strategy to precisely tailor the photoluminescence properties of the one-dimensional copper(I)-based halide Rb2CuBr3. Experimental results demonstrate that bright cold-white-light emission is achieved over a broad pressure range, with the photoluminescence quantum yield reaching 80.1% at 14.1 GPa. Integrated experimental and theoretical analyses reveal that this pressure-induced white-light emission arises from compression-driven reconfiguration of the energy-level structure associated with self-trapped states. Furthermore, this reconfiguration gives rise to novel multiple self-trapped exciton states in the long-wavelength region. This phenomenon is intimately associated with a pronounced structural phase transition and significant distortion of the [CuBr4] tetrahedra. Our study establishes high-pressure treatment as an effective strategy for modulating the photophysical properties of all-inorganic copper(I)-based systems, enabling bright white-light emission.