Synthesis of highly luminescent CsPbBr3@Cs4PbBr6 nanocrystals via ligand-assisted reaction

All-inorganic lead halide perovskite nanocrystals (NCs) have attracted enormous attention owing to their excellent optical properties such as ultrahigh photoluminescence quantum yield (PLQY), narrow full width at half maximum (FWHM) and broad emission spectra tunability. In this study, we reported the synthesis of colloidal perovskite NCs based on CsPbBr3@Cs4PbBr6 composite structure. With the assistance of Tetraoctylammonium bromide (TOAB) ligands, the prepared CsPbBr3@Cs4PbBr6 NCs show high PLQY of 94.7% and enhanced stability. The crystal morphology and phase structure of the CsPbBr3@Cs4PbBr6 NCs were investigated by HRTEM and XRD measurements. In addition, the crystal morphology of CsPbBr3@Cs4PbBr6 NCs presents cubic and circular particles with an average size of 9.3 nm. Compared with CsPbBr3 NCs, the diphase CsPbBr3@Cs4PbBr6 composite materials can perform higher optical properties due to the in-situ passivation of the generated Cs4PbBr6 NCs. Furthermore, the fabricated LED device exhibits bright white light emission with a color coordinate of (0.335, 0.337), the corresponding color temperature of 5390 K and a color rendering index of 82.1 under the injection current of 30 mA. These results demonstrate that the obtained CsPbBr3@Cs4PbBr6 NCs have a potential application in white light-emitting and display devices.