Study On The Influence Of Composite Phase And Ni²⁺ Doping On The Optoelectronic Properties Of CsPbBr₃

All-inorganic lead halide perovskite material Cs Pb X₃(X=Cl,Br,I)has been applied in the fields of solar cells,electroluminescence,lasers and displays due to its low cost,excellent carrier mobility and light absorption coefficient.To improve the stability and quantum yield of CsPbBr₃,a composite structure of CsPbBr₃/Cs Pb₂Br₅ was constructed in this work,based on the excellent stability and photoelectric properties of CsPbBr₃ and Cs Pb₂Br₅.In addition,doping engineering strategy is also adopted by partially replacing Pb²⁺with Ni²⁺to study the effect on the photoelectric performance by doping Ni²⁺into CsPbBr₃.This work mainly focuses on the influence of constructing composite structure and doping engineering on the photoelectric properties of CsPbBr₃,as follows:(1)The cooling crystallization method was used to synthesize the 3mm-sized CsPbBr₃/Cs Pb₂Br₅ crystal by controlling the temperature and stirring speed.A layer of Ag electrode was deposited on the surface of the crystal through evaporation process to prepare a simple optoelectronic device.It shows that the photodetector presents excellent photoelectric properties,which shows strong absorption in the ultraviolet and visible band,low dark current(30 p A)and excellent photoresponse to 405 nm laser with 275 ms/295ms at 0.9 m W/cm~2.(2)The CsPbBr₃ sample was synthesized by a simple solution method,and then was convert to Cs Pb₂Br₅ induced by water.The CsPbBr₃/Cs Pb₂Br₅ composite film was prepared through thermal evaporation process.It shows that the CsPbBr₃/Cs Pb₂Br₅composite film photodetector has excellent photo response to 405 nm laser,which obtains a larger photocurrent(4.84 n A)at 0.9 m W/cm~2 and faster photoresponse time(667 ms/736ms).(3)The anti-solvent method was used to dop Ni²⁺into CsPbBr₃,and the influence of Ni²⁺doping on the photoelectric properties of CsPbBr₃ was explored.The results show that the fluorescence quantum yield of the doped sample powder is significantly improved from 0.1%to 39.27%compared to the undoped sample.At the same time,the absorption peak and fluorescence peak position of the doped sample present a slight blue shift,indicating that Ni²⁺has a certain influence on the electronic structure of CsPbBr₃.Bi-Gaussian fitting proves that two fluorescence centers contribute to the fluorescence of the doped samples,which are cubic phase CsPbBr₃and Cs(Ni Pb)Br₃ respectively.The research on the influence of Ni²⁺doping on the optical properties of CsPbBr₃ make contribution to its application in the field of optoelectronics.