Study On The Preparation And Photoelectric Properties Of Er-doped MAPbBr₃ Single Crystals

Perovskite single crystals have attracted widely concern and study due to the superior characteristics,such as low defects,no grain boundaries,adjustable band width,long carrier mobility,carrier diffusion length and so on,which obtain great advantages in perovskite solar cells,photodetectors,light-emitting diodes and lasers applications.The bandgap of perovskite single crystals can be adjusted to improve the performance by doping,however,B-site doping has rarely been reported.Therefore,the main content of this thesis is to prepare a B-site-doped Er-MAPbBr₃ single crystal,and explore the reasons why Er doping affects the performance and applications of the single crystal.Firstly,large-scale MAPbI₃ and FAPbI₃ single crystals were prepared in a short time by the inverse temperature crystallization method,and MAPbBr₃ single crystals were prepared by the anti-solvent crystallization method.Next,perovskite single crystals were used as raw materials in the perovskite solar cell,which can reduce manufacturing costs and errors.The maximum efficiency of the solar cell can reach 18.8%when the component of perovskite layer is Cs_0.02FA_0.833MA_0.147Pb(I_0.85Br_0.15)₃,and the responsivity of forward and reverse scan is only 1.7%.It is proven that perovskite single crystals applied in solar cells can effectively alleviate the I-V hysteresis problem.In order to further improve the performance of single crystals,we fabricated B-site doping of MAPbBr₃ single crystal with Erbium?Er?,large-scale Er-MAPbBr₃ single crystals were prepared.The doping of Er not only improve the PL emission of the single crystal but also enhance the electronic characteristics.MAPbBr₃ and Er-MAPbBr₃ single crystals were used to prepare planar photodetectors.The performances of photodetectors were enhanced with doping Er.The photocurrent of Er-MAPbBr₃ photodetector is two times than that of MAPbBr₃ photodetector.The highest responsivity of Er-MAPbBr₃single crystal photodetector can reach 99.98 A W^-1 under 520 nm,15?W cm^-2.More importantly,Er-MAPbBr₃ and MAPbBr₃ photodetectors have a self-powered feature and can work continuously without bias voltage.This is of great significance for the future development of perovskite photodetectors.Next,we studied the enhanced photoluminescence and photoconductivity characteristics of MAPbBr₃ and Er-MAPbBr₃ single crystals under different conditions.The luminescence peaks of single crystals below 140K will split.We fit the PL peak of10 K,it would be more appropriate to fit the BE emission with an Asymmetric Double Sigmoidal?Asym2Sig?peak.Combined with the TRPL spectrum,it can be found the high-energy peak comes from free exciton emission peak and low-energy peak origins from bound exciton emission peak which is derived from the defect energy level in the single crystal.It can be found that the intensity of the bound exciton emission peak of Er-MAPbBr₃ single crystal is significantly enhanced through the PL spectrum under different light intensities,which indicates the Er dopants create shallow level defects that enhance the photoluminescence and photoconductivity properties of MAPbBr₃ single crystals.