Controlled Synthesis And Blue-Violet Emission Of Cesium Lead Halide Perovskite Nanocrystals

In the 21st century,motivated by the rapid development of the information industry,light-emitting devices（LED）are widely used.The color performance of the light-emitting devices is determined by the intrinsic luminescent characteristics of the luminescent materials.The cesium lead halide（CsPbX₃）perovskite nanomaterials embrace the excellent properties of high quantum yield,tunable photoluminescence（PL）emission spectra,narrow emission bandwidths,and high absorption coefficient,making them candicate materials for the applications in the field of display and optoelectronics.As we all know,blue-violet light emitting materials are crucial in the light-emitting devices.This paper focuses on synthesis and modification of cesium lead halide perovskite nanocrystals with blue-violet emission,including controlled synthesis of CsPbX₃（X=Cl,Br）nanostructures and improving their luminescent properties.The main research work is as follows:Monodisperse CsPbCl₃ perovskite nanomaterials were synthesized via hot-injection method,and HCl was added after the purication of quantum dots.The structure and morphology of theses quantum dots were slightly influenced by the post-treatment with HCl,and no shift were observed in their emission peak.In contrast,the elemental composition on the surface of these quantum dots determined by XPS analysis was changed after post-treatment.More important,the exciton binding energy were enlarged and the average PL decay lifetime was prolonged,and thus the PL quantum yield（PLQY）of these CsPbCl₃ quantum dots treated by HCl was improved up to 40 times.The improvement is due to the fact that chlorine ions provided by HCl repaired the anion vacancy defects on the surface of quantum qots.A new strategy using oleic acid-capped precursor was developed to synthesize CsPbBr₃ nanocrystals.The quantum confined CsPbBr₃ nanocrystals were prepared under room temperature.With the assist of fatty acid-capped precursor,the crystallization and the following growth rate was retarded,thus the morphology and size of theses nanocrystals were tailorable and their stability was improved.Ultrathin CsPbBr₃nanowires and CsPbBr₃ nanoplates with varied thickness were prepared by simply adjusting the amount of octylammonium cations and oleic acid,with the PL emission peaked in the range of 448⁴60 nm.The quantum confinement effect enabled the CsPbBr₃ nanocrystals to exhibit blue-violet light emission with a quantum yield of up to57.38%.