Optical Properties Of Organic-inorganic Hybrid Perovskite Quantum Dots

Perovskite quantum dots（QDs）have infinite potential and broad prospects for photoelectric applications due to their excellent optical properties,tunable emission peaks in the whole visible range,narrow emission peaks（12 nm-42 nm）and high quantum efficiency（50%-90%）.As one of the typical quantum dots,organic-inorganic hybrid perovskite quantum dots have high quantum efficiency because of their large exciton binding energy and quantum confinement effect.Recent studies have shown that perovskite quantum dots can adjust their optical properties by adjusting the composition,size and morphology of quantum dots.The main research work of this paper is to explore the synthesis of organic-inorganic perovskite quantum dots and the adjustment of halogen components,to study the influence of halogen ions on the luminescence of quantum dots;to explore the self-assembly process of quantum dots and the polarization characteristics of organic-inorganic perovskite quantum dots self-assembly films,so as to provide a solid basis for the future application and research of organic-inorganic hybrid perovskite quantum dots.The main contents are as follows:（1）Organic-inorganic hybrid perovskite quantum dots with adjustable emission wavelength were prepared.Organic-inorganic hybrid perovskite CH₃NH₃PbX₃（X=Cl,Br,I）quantum dots were synthesized by ligand-assisted reprecipitation technology.The size of perovskite quantum dots was adjusted by precisely adjusting the halogen composition and proportion of organic-inorganic hybrid perovskite CH₃NH₃PbX₃quantum dots,and then the forbidden bandwidth of quantum dots was changed to control the light wavelength.Two halogen components,including Br^-and Cl^-doped and I^-and Br^-doped organic-inorganic hybrid perovskite quantum dots,were accurately regulated.By preparing perovskite quantum dots with different halogen composition ratios,the luminescence wavelength was covered in the visible region.（2）Organic-inorganic hybrid perovskite quantum dot films with various light-emitting wavelengths were prepared.CH₃NH₃PbI_xBr_3-x quantum dots with various light-emitting wavelengths were synthesized by ligand-mediated conversion synthesis,and the ratio of halogen was controlled.A group of CH₃NH₃PbI_xBr_3-x-x quantum dot films based on various halogen components were prepared by compounding the quantum dots with polymer polymethyl methacrylate（PMMA）.Flexible perovskite quantum dot films with different light-emitting colors were fabricated and tested.It is proved that the stability of quantum dots is improved by the combination of quantum dots and PMMA.（3）The morphology of CH₃NH₃PbBr₃ quantum dots was controlled by self-assembly.CH₃NH₃PbBr₃ quantum dot powders were prepared by emulsification synthesis.High concentration quantum dot solutions were prepared and self-assembled.The self-assembled films of CH₃NH₃PbBr₃ quantum dots were prepared.The polarized luminescence properties of the films were realized.