Preparation And Luminescence Properties Of Yb³⁺-doped CsPbCl₃ Core-shell Quantum Dots

All-inorganic halide perovskite（CsPbX₃,X=Cl,Br and I）materials have been rapidly developed in the field of photovoltaics and luminescence in recent years due to their excellent optical and optoelectronic properties.However,the low absolute fluorescence quantum yield（PLQYs）and poor stability of CsPbCl₃ quantum dots make their applications in the field of luminescence greatly limited.Therefore,optimizing and modifying materials to improve the quantum yield of materials and expand the application range of materials on the basis of maintaining excellent properties is an urgent challenge to be solved.In this dissertation,CsPbCl₃ quantum dots are used as the main raw materials,and the overall quantum yield of CsPbCl₃ quantum dots is improved by incorporating rare earth ions Yb³⁺.The preparation conditions of Yb³⁺doped CsPbCl₃ quantum dots are optimized,a method of coating the shell layer on the basis of Yb³⁺doped CsPbCl₃quantum dots is introduced to improve the luminescence performance of perovskite quantum dots CsPbCl₃,and the application of CsPbCl₃:Yb³⁺core-shell quantum dots in near-infrared LEDs is explored.The main research results are summarized as follows:The all-inorganic perovskite CsPbCl₃:Yb³⁺quantum dots were synthesized by thermal injection,and the effects of reaction temperature and Yb³⁺doping on the performance of CsPbCl₃ quantum dots were explored.The results show that the luminescence performance of the prepared materials is optimal at 240℃ and the doping amount is 0.2 mmol.By comparing the relationship between the intensities of the two peaks with temperature,the characteristics of monitoring temperature based on the fluorescence intensity ratio were realized,and the relative sensitivity reached 5.7%K^-1when the temperature was 316 K.In addition,the upconversion co-luminescence property was discovered by excitation of Yb³⁺doped CsPbCl₃ quantum dots with a 980 nm laser.A method for synthesizing CsPbCl₃:Yb³⁺@CsPbCl₃ core-shell structure quantum dots was provided,and the effects of different core-shell thicknesses on the luminescence performance of CsPbCl₃:Yb³⁺quantum dots were explored.The results show that the luminescence performance of Yb³⁺doped CsPbCl₃ quantum dots at 980 nm is enhanced after the cladding layer.The fluorescence lifetime of Yb³⁺at 980 nm increases with the increase of core-shell thickness,and the maximum lifetime reaches 2 ms,approaching its radiation limit.The shell internalizes the Yb³⁺ions on the surface of the material,thereby improving the stability of Yb³⁺at 980 nm.In addition,the universal practicability of this synthesis method was explored by changing the structure of the shell layer and synthesizing CsPbCl₃:Yb³⁺@Cs Mn Cl₃ by using the same method.Finally,the application prospect of CsPbCl₃:Yb³⁺@CsPbCl₃ quantum dots was explored,the prepared materials were applied to near-infrared LED,and near-infrared LED was used with near-infrared cameras to achieve excellent night vision illumination effects and non-destructive testing.