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

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 Wrad−1.