Performance Improvement Of CsPbBr₃ Quantum Dots And QLEDs

All-inorganic perovskite quantum dots have drawn widespread attention in the field of display and luminescence due to their simple preparation methods,adjustable luminous color,and extremely narrow fwhm.In this paper,the optical stability of Cs Pb Br₃ QDs used for QLEDs was improved by reducing the defects of the material.We also adjusted the organic ligand content and film fabrication process to optimize the quality of the Cs Pb Br₃ QDs film,to propose device light stability.The contents are as follows:CsPbBr₃ QDs with monodispersity were synthesized by hot injection method.The organic ligand content on the surface of Cs Pb Br₃ QDs film was reduced by Ar plasma processing technology,which could improve carrier transport performance.From J-V curves of QLEDs with ITO/PEDOT:PSS/PVK/QDs/TPBi/Li F/Al,the current density was increased after Ar plasma treatment,and maximum EL intensity of the device increased from 4.5?10⁵ to 9.1?10⁵.The core-shell CsPbBr₃/Cs₄PbBr₆ QDs were prepared by multiple injections of cesium oleate in a bromine-rich environment and was certified by HRTEM photos.The PLQY of Cs Pb Br₃/Cs₄Pb Br₆ QDs was reached to 94.99%,which was much higher than normal Cs Pb Br₃ QDs.The improved optical stability of core-shell structure quantum dots were measured in harsh environment,such as polar solvents,high temperature and UV light exposure.The discussion showed that the shell structure effectively reduced the defects density of Cs Pb Br₃ QDs and inhibited the non-radiative recombination process.The stability of Cs Pb Br₃/Cs₄Pb Br₆ QDs based QLEDs device has also been improved.In order to improve the film quality of the Cs Pb Br₃ QDs light-emitting layer,the pre-arranged PVK film was treated by Ar plasma processing technology.The thickness,density and uniformity of the light-emitting layer were significantly improved due to the increased adhesion of the PVK film.The experimental results also found that the hole mobility of the treated PVK organic hole transport film was reduced from 6.42?10^-6 cm²/V·s to 2.11?10^-6 cm²/V·s.Although the carrier transport performance was decreased,the corresponding QLEDs showed better luminous performance due to the significantly improved quality of light-emitting layer film and interface contact with the hole transport layer.