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

Abstract

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 Rb2ZrCl6 microcrystal was synthesized by hydrothermal method for the first time. The Rb2ZrCl6 microcrystals exhibit a blue-white light emission with high photoluminescence quantum yield of 60% and a large Stokes shift. The Rb2ZrCl6 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 Rb2ZrCl6 microcrystals show a remarkable stability against heat, ultraviolet light and environmental water/oxygen. Afterwards, we used the Rb2ZrCl6 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 Rb2ZrCl6 can therefore be deemed as a reliable light emitter for high-performance WLEDs.