Red-Emitting Perovskite Variant Cs2PtCl6 Phosphor: Material Design, Luminous Mechanism, and Application in High-Color-Rendering White Light-Emitting Diodes

Recently, A 2 BX 6 -type halide perovskite variant phosphors have been applied for white light-emitting diodes (LEDs) due to their superior photoluminescence properties, excellent stability, and low-cost solution-processability. However, the reported white LEDs, particularly the all-A 2 BX 6 white LEDs, exhibit insufficient color rendering due to the shortage of red light. In this work, through a rational material design, a red-emitting perovskite variant Cs 2 PtCl 6 phosphor is developed. The synthesized Cs 2 PtCl 6 powders exhibit a relatively narrow bandgap of 2.91 eV and an intrinsic broadband red emission centered at 670 nm, which is attributed to the triplet self-trapped excitons associated with the Jahn−Teller-distorted [PtCl 6 ] 2− octahedra in the excited state. Using Cs 2 PtCl 6 as the red phosphor component, an all-A 2 BX 6 white LED is constructed, achieving a standard white light with a Commission Internationale de l'Eclairage chromaticity coordinate of (0.33, 0.33), a correlated color temperature of 5318 K, and a record high color rendering index of 90. This work represents a significant step toward the application of A 2 BX 6 perovskite variant phosphors for solid-state lighting.