Highly luminescent and stable lead-free cesium copper halide perovskite powders for UV-pumped phosphor-converted light-emitting diodes
Intrinsic broadband emitters enabled by self-trapped excitons (STEs) have recently emerged as the next generation phosphors for lighting applications. The self-trapped excitons are generally localized within nanometer scale with strong exciton binding energy, which minimizes the influence of external defects or thermal disturbances. Thereby, high photoluminescence (PL) quantum yield and good stability can be achieved in STE emitters.
In this study, Xie et al. develop a simple and energy-saving route to synthesize lead-free Cs3Cu2X5 (X=I, Cl) with STE emission, which originates from Jahn-Teller distortion of the Cu tetrahedral site. These materials exhibit relatively high PL quantum yield up to ~60% with good thermal stability and photostability. Moreover, UV-pumped LEDs are realized using blue emitting Cs3Cu2I5 and green emitting Cu3Cu2Cl5 as phosphors. This work successfully demonstrates the low-cost synthesis of efficient phosphor materials with self-trapped exciton emission. Future work includes further efficiency improvement, and exploration of GaN LED pumped STE phosphors.