Preparation And Photostability Of CsPbBr₃/CdSe/Al Core-shell Heterostructure

Perovskite Quantum Dots（PQDs）show great potential for applications in devices such as light emitting diodes（LED）,photodetectors,lasers and solar cells due to their high brightness,high defect tolerance,tunable emission wavelength,high color purity and nearly 100%photoluminescence quantum yields（PLQYs）.However,the poor long-term stability of PQDs has limited their application in optoelectronic devices.The large number of electrical interactions between CsPbBr₃ and CdSe,and the ability of Al to form Al₂O₃ self-passivating layer on the surface of QDs,Therefore,in this paper,starting from the synthetic route of PQDs,the stability was improved by coating the surface with CdSe and Al,and the prepared CsPbBr₃/CdSe/Al QDs with core-shell structure were applied in white LED（WLED）.Details of the study are as follows:1.CsPbBr₃ QDs were synthesized by hot injection method,then a layer of CdSe and a layer of Al were epitaxially grown on the surface of CsPbBr₃ QDs by using a simple method of ion layer adsorption and reaction method,and finally CsPbBr₃ QDs,CsPbBr₃/CdSe and CsPbBr₃/CdSe/Al core-shell QDs samples were obtained.The luminescence performance of the three samples was characterized and tested,and the results showed that the CsPbBr₃/CdSe and CsPbBr₃/CdSe/Al core-shell QDs still maintained good luminescence performance and more than 80%PLQYs.2.The stability of CsPbBr₃,CsPbBr₃/CdSe and CsPbBr₃/CdSe/Al QDs was tested by sealing them in natural light environment,and by monitoring their spectra for one week,it was found that the stability of QDs with core-shell structure was much higher than that of bare CsPbBr₃ QDs,especially after covering the Al layer,the stability of CsPbBr₃/CdSe/Al core-shell QDs was still retained more than 70%after one week under natural environment.3.A WLED based on CsPbBr₃/CdSe/Al QDs was fabricated and tested for color gamut,color purity and spectral stability.The results show that the CsPbBr₃/CdSe/Al core-shell QDs cover 129%of the National Television Systems Committee standard and have high color purity and are stable in emitting cool white light at different voltages and at 20 m A for 60 h.The CsPbBr₃/CdSe/Al core-shell QDs is further validated for its outstanding luminescence performance and stability in practical applications.