Lead-free vacancy‐ordered halide double perovskite microcrystals are new alternatives to lead-based halide perovskite materials for lighting applications; however, they are limited by harsh synthesis conditions and low quantum efficiency. Hence, a facile solution recrystallization method was used to synthesize Te 4+ -doped Rb 2 SnCl 6 phosphors. Via Te 4+ doping, the phosphors show a yellow–green emission at 550 nm and a broadband emission line width of approximately 97 nm, achieving a high photoluminescence quantum yield of 74.2%, arising from the Te 4+ 1 S 0 → 3 P 1 self-trapping exciton transition. The Te 4+ -doped Rb 2 SnCl 6 microcrystals are subsequently used to fabricate a white light-emitting diode device, which shows a high color-rendering index of 97.1 and a correlated color temperature of 4739 K. This work reports a facile method to synthesize alloy double perovskite phosphors, opening up new avenues for the development of environment-friendly lighting applications.
Shuaichen Si,Xiaoxuan Guo,Weijiang Gan,Xuejie Zhang,Bang Lan,Man-Rong Li,Jing Wang
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 A 2 B(IV)X 6 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 Rb 2 SnCl 6 :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 Rb 2 SnCl 6 :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.
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