Phase composition and luminescent properties of cesium lead bromide perovskite nanopowders

Halide perovskite nanopowders were synthesized by ligand-assisted re-precipitation technique with different volume ratios of mixture solution to antisolvent (toluene). It was found that with an increase in the proportion of toluene, the phase formed as a result of recrystallization changes predominantly from Cs4PbBr6 to the CsPbBr3, while less stable CsPb2Br5 phase was also discovered. The change in the phase composition of powders obtained with different volume ratios of mixture solution to toluene is explained by the salting out effect of slightly soluble compounds. The phase composition had a correlation with the crystal size distribution, as well as with the photoluminescence quantum yield. Optical properties, including absorption spectra, photoluminescence excitation and luminescence spectra were investigated. Nanopowders obtained with a ratio of the mixture of solution to toluene of about 1:0.9 had the maximum quantum efficiency. The following was associated with the formation of low-dimensional CsPbBr3 "slabbed" crystals sticked on rhombohedral Cs4PbBr6 crystals. The composite film based on nanocrystals and thermoplastic polyurethane was made by hot pressing, the potential of its use as a phosphor coating for an ultraviolet LED was shown.