Pressure Opens Up the Radiative Recombination Channels Toward Bright White‐Light Emission

Abstract Despite the exceptional stability and nontoxic nature of all‐inorganic silver halides, their limited photoluminescence efficiency significantly restricts the applications in optoelectronics and solid‐state lighting. Here, it successfully achieves an intriguing pressure‐induced emission (PIE) of bright white‐light from “0” to “1” in the 1D lead‐free all‐inorganic halide Cs 2 AgI 3 . Moreover, the pressure sustaining interval for PIE can be even up to 14.2 GPa. The increased halide distortion within the [AgI 4 ] 3− tetrahedron upon compression is responsible for promoting electron‐phonon coupling and driving the emission of self‐trapped excitons. Furthermore, transient absorption spectra and first‐principles calculations confirm that applying pressure opens up the radiative recombination channels associated with “dark” to “bright” self‐trapped states through significantly increasing the non‐radiative transition barrier. The research not only establishes a correlation between structural properties and optical properties, but also provides deep insights into single‐component bright white‐light emission.