Lead-free Halide Perovskites With ≈100% PLQY and Dual-Color Emission for White Light-Emitting Diodes

Lead-free halide perovskites (LHP) have attracted extensive attention in the field of next-generation solid-state lighting. However, single perovskite phosphor with tunable white-light emission and ultra-high photoluminescence quantum yield (PLQY) are rare. Here, the tunable dual-color emission LHP phosphor is developed with a near-unity PLQY of 99.5%. The LHP phosphor comprises Cs 2 NaInCl 6 : Sb 3+ /Bi 3+ and Cs 2 InCl 5 ·H 2 O: Sb 3+ /Bi 3+ crystals, with the transition between these two perovskite structures being adjustable by the concentration of Na + . The addition of NaCl inhibits the hydrolysis of the [Sb(H 2 O)Cl 5 ] 2− octahedron, resulting in 3D connected [SbCl 6 ] 3− octahedron with less Jahn-Teller distortion, and the PLQY of LHP is greater than 90%. Finally, the white-light diode device is fabricated by assembling the LHP with a ultraviolet light-emitting diode  chip and the white light-emitting diode device achieved Commission Internationale de l'Eclairage color coordinates of (0.34, 0.33), correlated color temperature of 4936 K, and a high color rendering index of 92.9. The LHP perovskite exhibited multimodal luminescence when excited by 365, 335, and 310 nm UV light, showing the multi-mode anti-counterfeiting capabilities of the LHP crystals.