Cu (I)-Based Rare-Earth Halide with Near-Unity PLQY for LED and X-ray Scintillation Applications

Low-dimensional Cu (I)-based halides have attracted considerable attention due to their low toxicity and exceptional optoelectronic properties. Herein, we reported novel zero-dimensional (0D) Cu (I)-based halides of Rb₈CuY₃Cl₁₈, in which three [YCl₆]^3- octahedra are connected to Cu⁺ ions, forming a paddle-wheel-like [Cu₂(YCl₆)₃]^7- cluster. The isolated Cu (I) coordinated rare-earth halide clusters endow highly localized electronic structures, resulting in a near-unity photoluminescence quantum yield (PLQY) of 96%. The strong electron-phonon coupling facilitates the formation of self-trapped excitons (STEs), exhibiting intense cyan emission (≈491 nm) along with a large Stokes shift of 1.78 eV. A cyan light-emitting diode (LED) was fabricated with excellent color stability over a broad range of driving currents. Furthermore, Rb₈CuY₃Cl₁₈ exhibits a decent detection limit of 134.8 nGy_air s^-1 and good radiation resistance stability with negligible afterglow. The scintillation screen based on Rb₈CuY₃Cl₁₈ achieves a high spatial resolution of 8 lp mm^-1. These findings open new avenues for developing low-dimensional Cu (I)-based halides for multifunctional optoelectronic applications.