Effect Of Ni²⁺ Doping On The Fluorescence Properties Of Bromine Lead Cesium All-inorganic Perovskite Nanocrystals

All-inorganic halide perovskite nanocrystals（NCs）are a new class of semiconductor materials,which have excellent photoelectric properties and have great potential in applications such as lighting,laser,photon detection,flat panel display,and photovoltaics.Although the research on the perovskite family has made remarkable progress,in terms of commercial application,perovskite still has many problems that need to be solved,such as inorganic lead halide perovskite CsPbBr₃has strong lead toxicity and perovskite Mine-related CsPb₂Br₅ nanocrystals have high stability but it is difficult to achieve luminescence regulation.In view of the above problems,this paper conducts a modification study of transition metal Ni ions instead of lead ions on all-inorganic lead-halogen perovskite CsPbBr₃ quantum dots.Optimize the synthesis process to prepare the dual-phase CsPbBr₃-CsPb₂Br₅composite material with tunable luminescence characteristics and explore its luminescence mechanism.The research contents of this article are listed as follows:1.In view of the problem of the high lead toxicity of inorganic perovskite CsPbBr₃,a transition metal Ni²⁺with the same valence state was proposed to replace Pb²⁺to effectively reduce the content of Pb²⁺in perovskite quantum dots.In-depth study of the traditional heat injection method and optimization of the synthesis part,obtained a simpler and safer method of preparing Ni²⁺doped CsPbBr₃ quantum dots,and then qualitative and quantitative analysis of the quantum dot crystal structure,observe its morphology,analyze optical properties The research results indicate that Ni²⁺was successfully incorporated into the CsPbBr₃ quantum dot lattice;the actual molar ratio of Ni and Pb was quantitatively measured by ICP-MS.The stability of Ni-doped perovskite quantum dots was studied by characterizing and analyzing the photoluminescence spectra（PL）and fluorescence quantum efficiency（PLQY）of undoped CsPbBr₃ quantum dots and Ni²⁺doped CsPbBr₃ quantum dots.The results show that the highest PL intensity of Ni²⁺-doped CsPbBr₃ quantum dots is twice higher than that of undoped CsPbBr₃quantum dots,showing a single green light emission at⁵20 nm;and after doping Ni²⁺in CsPbBr₃ quantum dots,the The fluorescence lifetime is significantly increased,and both light stability and damp heat stability are enhanced.2.Using the chemical redeposition method without any organic ligands,by doping NiBr₂ with different concentrations,Ni-doped biphasic CsPbBr₃-CsPb₂Br₅composite crystals were induced and their structures and luminescence properties were characterized.The results show that by changing the concentration of NiBr₂,the luminescence color of the CsPbBr₃-CsPb₂Br₅ nanocomposite crystal can be adjusted between yellow-green and green light.With the increase of NiBr₂concentration,the photoluminescence spectrum of the two-phase CsPbBr₃-CsPb₂Br₅ composite material gradually showed blue shift.After optimizing the concentration of doped NiBr₂,the luminescence performance is the best when it reaches 200%,and the fluorescence quantum efficiency is 39.3%,which is significantly improved compared with 3.3%for undoped CsPbBr₃ nanocrystals.