Lead-free perovskite variant Rb2SnCl6:Te based phosphor-sapphire composite for high-power laser-driven lighting

Abstract

Lead-free perovskite variants have attracted wide interest because of the lead-free feature and broadband emission originated from self-trapped exciton (STE), which show great advantages in lighting applications. Especially the tetravalent Te-doped A2B(IV)X6 perovskite variants, which have efficient excitation in the blue range and strong emission in the yellow region as well as high photoluminescence quantum yield, is particularly suitable for solid-state lighting. Despite these fascinating properties, it is still not suitable for high-power illumination due to its poor thermal resistance and severe light saturation feature at high laser power density. Herein, we develop a lead-free perovskite variant Rb2SnCl6:Te based phosphor-sapphire composite (PSC) fused with low-melting glass through a simple screen-printing and sintering process. The as-prepared PSC shows yellow-green emission at 570 nm, due to the combination of Te luminescent center and Jahn-Teller-like STE, and exhibits a high thermal conductivity of 37.06 W m−1 K−1. Benefitted from the high thermal conductivity of the sapphire substrate, the PSC exhibits the great improvement in light saturation behavior, heat dissipation, and chromaticity stability withstand the high-power blue laser, compared to Rb2SnCl6:Te phosphor, finally contributing to an excellent PLQY of 70.3%. In addition, by combining the PSC with the blue laser, a warm white light with a CIE chromaticity coordinate of (0.368, 0.344), and a correlated color temperature of 4129 K is achieved. These results demonstrate that this simple and low-cost fabrication method is expected to be widely used for various phosphors and the PSC can own excellent application prospects in high-power laser-driven lighting.