A novel material Cs 2 Rb x Ag 1- x In 0.875 Bi 0.125 Cl 6 with a special blue shift and application for white light LED devices.

Perovskite microcrystals have attracted wide attention and have been applied in extensive optical applications. The CsPbX ₃ perovskite poses a great threat to the environment due to the presence of lead (Pb), and there is an urgent need to improve the photoluminescence quantum yield. Therefore, a lead-free perovskite microcrystal material Cs ₂ Rb _x Ag _{1- x} In _0.875 Bi _0.125 Cl ₆ with a high photoluminescence quantum yield (PLQY) was synthesized by a convenient hydrothermal method, with comprehensive characterization of both the structure and optical performance at varying Rb ratios. Optimal properties were observed at x = 0.15 with bright white emission and a PLQY of 32.15%. Superior stability of the novel material in ethanol was observed under the radiation of an excitation light of 365 nm. Interestingly, a blue shift of the emission peak occurred after exposure to humid air, possibly due to the reconstruction of the crystal structure. Moreover, a LED device packaged with this novel material was developed with a desirable color temperature of 3190 K, promising for further lighting applications.