Study On The Regulation Of Fluorescence And Dielectric Properties In Doped Inorganic Halogenated Perovskite

In recent years,inorganic halogenated perovskite CsPbX₃（X=Cl,Br,Cl）has attracted extensive attention because of its high carrier concentration,adjustable band gap,high color purity and high defect tolerance.It can be used in many fields,such as solar cells,light-emitting LEDs,lasers and optoelectric detectors.Although it has shown great development potential in many aspects,there are also some problems that restrict its further application.In the field of light-emitting LED,the goal of high PLQY,high EQE and high stability blue halogenated perovskite nanocrystals and devices cannot be achieved at present due to uncontrollable defects,grain fusion,halogen separation and other reasons.Firstly,the PLQY and stability of blue halogenated perovskite were studied.By optimizing the experimental conditions and using the passivation and doping effect of Na ion,the preparation of high PLQY and high stability blue CsPbBr₃ nanosheets was realized.At the same time,CsPbX₃ also shows potential in the mutual regulation of electricity and light.This work also realizes the structural regulation of CsPbCl₃ by Sm doping of CsPbCl₃,and then significantly enhances the dielectric properties of the material.The specific research contents are as follows:（1）Firstly,using the improved heating method,the effects of these parameters on the fluorescence properties of the samples were found out by adjusting the initial temperature,Na/CS and heating time.It is found that the optimum experimental parameters of initial temperature,Na/CS and heating time are15℃,1 and 2min respectively.The emission peak of the sample with the best performance is 461 nm and the plqy is 45.85%.（2）Using the results of the previous step,the initial temperature,Na/CS and heating time were set as the best parameter values,and the amount of isopropanol in the reaction was further adjusted to improve the performance of the sample.CsPbBr₃ nanosheets with emission peak at 453.2 nm and PLQY of 94.67%were successfully synthesized,which maintained blue light emission for 40 days.And the performance of all samples is higher than that of the previous part.It shows that the optimal value of each parameter can effectively improve the performance of the sample,and it is necessary to further regulate the amount of IPA.（3）Different proportions of Sm³⁺doped CsPbCl₃ blocks were prepared by vacuum melting method.Sm³⁺was successfully doped into the lattice gap of CsPbCl₃,resulting in obvious distortion and expansion of CsPbCl₃ lattice,but the tetragonal phase remained after expansion.Moreover,the incorporation of Sm³⁺reduces the binding energy of Cs⁺、Pb²⁺、Cl^-,and greatly improves the dielectric constant of CsPbCl₃ at low frequency,which increases from 372.6（x=0）to 1.28M（x=0.06）at 100Hz.