Microstructure Control Of CsPbCl₃ Perovskite Quantum Dot Materials And Research On Light Emitting Diodes

All-inorganic lead halide perovskite quantum dots have excellent optical properties such as low cost,narrow emission spectrum,tunable band gap,and high quantum efficiency,and are considered to be the most promising optoelectronic materials in the next decades,photodetectors,solar cells and other fields have broad application prospects.Based on white LED applications,the three primary colors（red,green,and blue）require good color purity and brightness.However,the toxic elementPbcontained in lead halide perovskites can cause harm to the human body and the environment.Therefore,how to reduce or replace the heavy metal lead is a challenge for scientists now.In addition,due to the inherent ionic bond properties of lead halide perovskite QDs and the influence of organic capping ligands,perovskite QDs rapidly degrade in the presence of moisture,air,and polarity,greatly reducing their stability.This has also become a major factor restricting its industrial application process.In order to solve the above shortcomings,many achievements have been made in the stability of green CsPbBr₃perovskite quantum dots.However,the progress of quantum dots in the red color gamut is not as good as that of green quantum dots.Generally,the PLQY of CsPbCl₃perovskite quantum dots is lower than 15%..Therefore,this thesis studies several problems existing in CsPbCl₃perovskite quantum dots,and the results are as follows:（1）By optimizing the synthesis conditions of CsPbCl₃perovskite quantum dots,the effect of thermal injection reaction temperature on the synthesis morphology of CsPbCl₃perovskite quantum dots was explored.On this basis,a Mn²⁺doping strategy was applied.The doping of Mn²⁺can reduce the content of toxic element Pb,and then improve the stability of certain perovskite quantum dots.Increasing the doping content of Mn²⁺,the duration of the intrinsic excitation peak is significantly improved;at higher doping content,a broad red emission is introduced through the dd transition of Mn²⁺,which broadens the emission spectrum of CsPbCl₃perovskite QDs range,improved optical properties,and increased the overall PLQY of CsPbMn Cl₃perovskite quantum dots to 54.32%.（2）Aiming to improve the environmental stability of CsPbMn Cl₃quantum dots,in order to further prevent the penetration of oxygen and water,a CsPbMn Cl₃@Si O₂nanocomposite structure material with a physical encapsulation shell was synthesized by the hydrolysis of aminopropyltriethoxysilane.The investigation of the PL spectrum within a few hours shows that the relative peak intensity of the coated perovskite quantum dots is maintained at 74%of the initial intensity,and the shift of the peak position is also suppressed.Finally,the nanocomposite structure material was fabricated into a white light-emitting device（WLED）,which exhibited good color coordination with CIE color coordinates of（0.31,0.35）under the illumination of a commercial In Ga N chip.Therefore,the nanocomposite-structured CsPbMn Cl₃@Si O₂perovskite quantum dots have excellent optical properties and simultaneously improve the stability to moisture and harmful polar solvents.Therefore,this encapsulation method can be used for illumination and pave the way for future applications in the display field.（3）The high density of defects and traps in perovskite quantum dots leads to nonradiative recombination,reducing the photoluminescence quantum yield.Therefore,on the basis of the above experiments,in order to further reduce the content of lead in CsPbMn Cl₃quantum dots and improve its photoluminescence quantum yield,ion co-doped CsPbMn Zn Cl₃perovskite quantum dots were synthesized using Zn²⁺as doping element.In this experiment,the effect of Zn²⁺doping on the fluorescence properties of CsPbMn Cl₃perovskite quantum dots was investigated.The results show that the doping of Zn²⁺enhances the emission peak intensity of Mn²⁺,suppresses the high density of defects and traps on the surface of CsPbMn Cl₃perovskite quantum dots,and improves the fluorescence quantum efficiency of co-doped quantum dots from 50.13%to 70.31%,and By controlling the content of doped Zn²⁺,the optimal doping ratio is Zn:Pb=2:1,which will greatly expand the future commercial application prospects of CsPbCl₃perovskite quantum dots.