Synthesis Of CsPbBr₃ Perovskite Nanocrystals Based On Sorbic Acid As Ligand And Preparation Of LED Devices

In recent years,lead halide perovskite materials have shown great prospect in the fields of photodetectors,solar cells and LEDs due to their excellent optoelectronic properties and simple preparation process.The all-inorganic metal halide perovskite quantum dots（Cs Pb X₃,X=Cl,Br,I）are considered to have a bright future in the new generation of displays due to their high quantum efficiency,their large exciton binding energy and their tunable emission in the visible spectral range.Traditionally,oleic acid is commonly used as a surface ligand for the synthesis of Cs Pb X₃.The quantum dots prepared with this long chain ligand,if used in LED devices,would have a large amount of oleic acid ligands around them,which would hinder carrier injection and transport in the device.Therefore,in this thesis,perovskite quantum dots were prepared using sorbic acid,a short chain molecule,as ligands and were used to prepare LED devices.The specific results are summarised as follows:（1）CsPbBr₃ quantum dots with a luminescence peak at 503 nm,a half-peak width of 24 nm and PLQY of 88.89%were prepared by a room temperature ligand-assisted re-precipitation technique using sorbic acid ligands.A number of tests have also confirmed its good crystal structure,microscopic morphology and stability.Cs Pb X₃ quantum dots with photoluminescence wavelengths from 448 nm to 559 nm were prepared by halogen modulation of the precursors.（2）CsPbBr₃ quantum dots prepared with sorbic acid as ligand were used as the light-emitting layer to prepare the LED devices.The devices exhibit good optoelectronic performance with a maximum brightness of 616 cd/m² and a peak EQE of up to 1.32%,which can be increased to 1.68%by treatment of the light-emitting layer film.Its relatively good stability was confirmed by comparison with oleic acid.