Enhancement Of The Stability Performance Of Organic-inorganic MAPbBr₃ Perovskite Quantum Dots

As a new type of quantum dot material,perovskite quantum dots（Pe QDs）have become the most potential optoelectronic materials in the field of display and illumination.Pe QDs showed excellent color purity and high fluorescence quantum yield,and the luminescence of the entire color gamut by simply adjusting the halogen ratio.However,Pe QDs were easily degraded under humid and light conditions due to their ionization and a large number of halogen vacancies,which seriously limits the further commercial application of Pe QDs,it was particularly important to improve the stability.In this study,we optimized the synthesis process of MAPb Br₃ quantum dots.Studied the effects of hydrophobic amino acid passivation on the morphology,luminescence and stability of Pe QDs.Studied the effects of material optimization on the morphology,luminescence and stability of Pe QDs.On this basis,we propose a stabilization mechanism for MAPb Br₃ Pe QDs.The results show that:（1）The synthesis process of MAPb Br₃ quantum dots is optimized.In the process of synthesizing MAPb Br₃ quantum dots using ligand-assisted reprecipitation,the corresponding quantum dots were synthesized by controlling each process parameter.The process parameters with the best performance of the MAPb Br₃ quantum dots were obtained by photoluminescence（PL）analysis.The results showed that when Pb Br₂ was added after ligand,the amount of oleic acid added was 200μL and the precursor:non-polar solvent was 1:10,the MAPb Br₃ quantum dot luminescence performance was the best.（2）In the synthesis of MAPb Br₃ quantum dots,the hydrophobic amino acids of Ala,Val and Met were used to passivate the MAPb Br₃ quantum dots.Studies have shown that amino acids promote the transition from free to a limited state of MAPb Br₃quantum dots,in which the larger the amino acid side chain alkyl group or the presence of-S-functional groups will exacerbate this transition process.The faster the transition to the defined region,the more crystalline the MAPb Br₃ quantum dots are,resulting in better aqueous phase stability but poor photostability.（3）The Pb Br₂ material was optimized with an anti-solvent assisted crystallization method and synthesize QDs-DMAPb Br₃.Studies have shown that DMAPb Br₃ provides a halogen-rich environment to reduces halide vacancy defects in quantum dots,leads to a decrease in the active site for photoinduced formation of superoxide.At the same time,the large radius of DMA⁺shortens the distance from the Br^-and forms a hydrogen bond with stronger binding force,thereby enhancing the electron coupling between the A-position cation and the Pb Br₆^4-octahedron,and enhancing the stability of Pe QDs.