Highly stable vacancy-ordered double perovskite Rb2ZrCl6 with broadband emission for down-conversion white light-emitting diodes

In recent years, the lead-halide perovskite materials have shown great potential in lighting fields due to their excellent photoelectric properties . However, lead toxicity and instability severely limit their practical application and commercial development. In this work, zero-dimensional vacancy-ordered double perovskite Rb 2 ZrCl 6 microcrystal was synthesized by hydrothermal method for the first time. The Rb 2 ZrCl 6 microcrystals exhibit a blue-white light emission with high photoluminescence quantum yield of 60% and a large Stokes shift. The Rb 2 ZrCl 6 has a high exciton binding energy and a strong electron-phonon coupling, which supports the formation of self-trapped excitons under light excitation and the generation of broadband emission. In addition, the Rb 2 ZrCl 6 microcrystals show a remarkable stability against heat, ultraviolet light and environmental water/oxygen. Afterwards, we used the Rb 2 ZrCl 6 microcrystals as the phosphors to fabricate a white light-emitting diode (WLED). The device demonstrates a color coordinate of (0.30, 0.32), a high color rendering of 90.0, and a good working stability, with no emission degradation over continuous 10 h operation. Together with the eco-friendly features and low-cost solution processability, the nontoxic Rb 2 ZrCl 6 can therefore be deemed as a reliable light emitter for high-performance WLEDs.