Researchers at the Dalian Institute of Chemical Physics at the Chinese Academy of Science have reported a series of bulk lead-free double perovskites which demonstrate the existence of parity-forbidden transition by photophysical characterization in Cs2AgInCl6 bulk crystal. The perovskites break the parity-forbidden transition and show warm white-light emission with broad emission across the entire visible spectrum, with the highest PLQE of 70.3%.

PLQE of 70.3% in lead-free halide double perovskites imageThe luminescence property of Cs2AgBi1-xInxCl6 (0 < x < 1) varied with increasing In content; the crystal structure of Cs2AgBi0.125In0.875Cl6 bulk crystal. Credit: Science China Press

The synthesized nanocrystals and microcrystals revealed that the PLQE decreases with the size decreasing, due to the enhancement of the PL quenching effect, caused by the increase of permanent defects. Furthermore, the Cs2AgBi0.125In0.875Cl6 bulk crystal possesses excellent stability. Therefore, it's promising as a new highly efficient warm white-light emitting material in LED applications.

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