Study On Photoelectric Properties And Stability Of Perovskite Quantum Dots Based On Doping And Modification Methods And Their Applications In Photoelectric Device

With the continuous advancement of science and technology,non-renewable energy has been scarce in recent years.The study of renewable new energy has become craze in the world.Light-emitting diode,as a device widely used in solid-state lighting and display,has attracted great attention from researchers for its stability,color tunability and low energy consumption.Perovskite quantum dots（QDs）,as a device widely used in solid-state lighting and display,have become the candidate materials of next-generation light-emitting diodes,such as their high color purity,high luminescence intensity,adjustable luminescence band gap,and low cost.However,the poor stability and the toxicity of Pb²⁺ions are the bottlenecks for QDs commercial applications.Therefore,it is particularly important to explore perovskite quantum dots with low toxicity,stable emission quality,and high emission quality.This thesis focuses on systematic research on preparation,structure,performance,and application in LED of perovskite QDs,and uses ion doping,surface passivation and other modification methods to improve the stability and photoluminescence properties.The conclusions are as follows:（1）By the room temperature method,Cs Pb_xSn_1-xBr₃ PQDs/a-Zr P are synthesized.Compared with the original Cs Pb Br₃ PQDs,Cs Pb_xSn_1-xBr₃ PQDs/a-Zr P have better optical performance and stability.Due to the inherent characteristics of a-Zr P nanosheets for high Pb²⁺absorptivity and good ability to exchange ions with Cs⁺,it promoted absorption and anchoring of perovskite quantum dots on the surface of a-Zr P.Therefore,the synthesized Cs Pb_xSn_1-xBr₃ PQDs/a-Zr P have higher exciton binding energy and stronger environmental stability.The PQDs provide a feasible method for producing stable and efficient perovskite quantum dots and shows that Cs Pb_xSn_1-xBr₃PQDs/a-Zr P are efficient down-conversion fluorescent materials for the preparation of high-efficiency LEDs.（2）Cs TFA was used to replace the traditional Cs₂CO₃ to prepare Cs Pb_xZn_1-xBr₃perovskite quantum dots.The PL intensity was greatly enhanced by 10%Zn²⁺ion doping,and the stability was further enhanced by surface passivation of the-TFA ligand.TFA ligands are passivating the Cs Pb_xZn_1-xBr₃perovskite surface via the binding of the C=O group with the uncoordinated Pb²⁺and the anchoring ability of CF₃ group on the metal cation.In addition,the stability in water of Cs Pb X₃ QDs,the TFA-passivatied,has been significantly improved.Finally,WLEDs are made by mixing green QDs and red commercial fluorescent powder on the Ga N chip.The WLED shows bright white light emission and great stability with a color coordinate of（0.316,0.329）and a correlated color temperature of 6326K.（3）Quasi-2D perovskite PEA₂Cs₂Pb₃Br₁₀ NCs film was synthestized by adjusting the n-value ratio,which has excellent optical properties.The properties of the quantum dots film were analyzed for the effects of the film surface morphology（SEM）,crystal structure（XRD）,photoluminescence（PL）,and fluorescence lifetime（TRPL）.Quasi-2D perovskite materials contain multiphase phases,which enable excitons to transfer between different phases.This restricts defects from capturing excitons,which is increasing recombination density,and enhancing PL emission intensity.Then,the green light-emitting LED device based on PEA₂Cs₂Pb₃Br₁₀ NCs was prepared.the EL fluorescence intensity continuously enhanced without luminescence oversaturation.And compared to the device based on 3D perovskite quantum dots,it has good and stable fluorescence emission.This indicates that the quasi-2D PEA₂Cs₂Pb₃Br₁₀QDs down-conversion materials provide a new idea for the next-generation of LED light-emitting devices.