Synthesis and optical properties of Cs4PbBr6 perovskite nanocrystals by the water assisted solid-state reaction (WASSR) method

Abstract

Green-emitting Cs₄PbBr₆ nanocrystals were synthesized by the water-assisted solid-state reaction method for the first time. Although CsPbBr₃ phases were observed in the X-ray diffraction (XRD) patterns of the perovskite nanocrystal samples as impurities, the XRD patterns of the samples could be well indexed to the trigonal Cs₄PbBr₆ structure. The Cs₄PbBr₆ perovskite nanocrystals showed a bright green emission with a narrow emission band centered at 518 nm with a full width at half-maximum of 26 nm. The photoluminescence quantum yield (PLQY) of the Cs₄PbBr₆ nanocrystals was 36.8%. The Cs₄PbBr₆ nanocrystal powder showed excellent durability at 85 °C and 85% humidity for 24 h, and retained 82% of the initial PL intensity. The Cs₄PbBr₆ nanocrystal film light-emitting diode chip showed a luminous efficacy of 30.6 lm W_rad⁻¹.