Synthesis and luminescence of ultrasmall CsPbBr3 nanocrystals and CsPbBr3/Cs4PbBr6 composites by one-pot method

All-inorganic perovskites CsPbX3 (X = Cl, Br, I) have attracted worldwide interest due to their excellent luminescent performances. Meanwhile, Cs4PbBr6 have been studied because they can enhance the luminescent efficiency and stability of CsPbBr3. Herein, we introduced a microfluidic method based on room-temperature supersaturated recrystallization to synthesize blue-emitting CsPbBr3 nanocrystals (NCs) and green-emitting CsPbBr3/Cs4PbBr6 NCs. The ultrasmall CsPbBr3 NCs emitted at a deep blue wavelength of 461 nm with the full width at half maximum (FWHM) of 15 nm. transmission electron microscopy (TEM) results demonstrated that ultrasmall CsPbBr3 NCs with the average particle size of 3.8 nm were synthesized and the CsPbBr3 NCs were crystallized as monoclinic structure. X-ray photoelectron spectrometer (XPS) analysis suggested that ultrasmall CsPbBr3 suffered from VBr defect and the surface passivation of Cs4PbBr6 possessed a low level of VBr defect density. The lifetime of CsPbBr3/Cs4PbBr6 was much longer than that of CsPbBr3. The results showed that ultrasmall CsPbBr3 NCs can be regarded as a source of blue-emitting material and CsPbBr3/Cs4PbBr6 NCs had a better stability.