Extreme electron-photon interaction in perovskite glass

The interaction of light with solids can be dramatically enhanced owing to electron-photon momentum matching. This mechanism is driven by either quantum confinement or long-range structural correlations in media with crystal-liquid duality. In this paper, we address a new strategy based on both phenomena for enhancement of the light-matter interaction in a direct bandgap semiconductor - lead halide perovskite CsPbBr$_3$ - by using electric pulse-driven structural disorder. The disordered (glassy) state allows the generation of confined photons, and the formation of an electronic continuum of static/dynamic defect states across the forbidden gap (Urbach bridge). Both mechanisms underlie photon-momentum-enabled electronic Raman scattering (ERS) and single-photon anti-Stokes photoluminescence (PL) under sub-band pump. PL/ERS blinking is discussed to be associated with thermal fluctuations of cross-linked [PbBr$_6$]$^{4-}$ octahedra. Time-delayed synchronization of PL/ERS blinking causes enhanced spontaneous emission at room temperature. Our findings indicate the role of photon momentum in enhanced light-matter interactions in disordered and nanostructured solids.