Efficient, Stable, and Tunable Cold/Warm White Light from Lead-Free Halide Double Perovskites Cs2Zr1-xTexCl6

Single-component materials with efficient, stable, and tunable cold/warm white-light emission are ideal candidates for lighting applications, which can overcome the problems of different deterioration rates and reabsorption effect in conventional mixed-phosphors strategy. Efficient white phosphors based on double halide perovskite have been reported via manipulating the parity transitions recently. However, the emission wavelength is nonadjustable. Herein, a lead-free double perovskite Cs 2 Zr 1− x Te x Cl 6 that exhibits efficient and stable white-light emission is reported. The introduction of Te 4+ results in bright self-trapped exciton (STE) emission, which endows Cs 2 ZrCl 6 matrix with multiple luminescent centers. Efficient white luminescence with tunable color temperature and high photoluminescence quantum yield (PLQY) of 61.5% (under 254 nm, CCT = 4039 K) and 96.1% (under 365 nm, CCT = 3313 K) is achieved. Efficient energy transfer between multiple luminescent centers and appropriate doping concentrations are the key points to achieve such highly efficient and tunable white emission. The as-synthesized Cs 2 Zr 1− x Te x Cl 6 composites exhibit a robust stability against heat, ultraviolet light, and environmental oxygen/moisture, which show little spectra variation with less than ≈ 20% efficiency loss after 980 h testing even under high temperature and UV light. These results indicate Cs 2 Zr 1− x Te x Cl 6 are promising single-component white-light-emitting phosphors for next-generation lighting and display technologies.