Perovskite Quantum Dots Light-emitting Diode Via Ligand Engineering And Interface Modification Of Functional Layer

Metal halide perovskite nanocrystals have attracted wide attention due to color-tunable,narrow emission peak,high color purity and high photoluminescence quantum yields(PLQYs).However,quantum dot light-emitting diodes(QLEDs)cannot meet the requirements of commercial applications due to the low luminance,low efficiency and poor stability of QLEDs.In my work,the strategy of organic-inorganic hybrid ligand passivation is adopted,and the appropriate hole transport layer material is selected.The Al₂O₃ buffer layer is prepared on the ITO electrode by atomic layer deposition(ALD)technology to improve the luminance and stability of the QLEDs,and study the mechanism of interface modification of carrier balance and stability improvement of the device by ALD technique.The main conclusions of this article are as follows:1.High-efficiency CsPbBr₃ perovskite quantum dots(PQDs)were prepared at room temperature.The surface of the PQDs is passivated with short-chain organic ligands DDAB and OTAc.The inorganic ligand ZnBr₂ further passivates the bromine vacancies, which effectively realizes the passivation of the surface defects of the PQDs,promotes the radiation recombination of excitons,and achieves PLQY close to 100%.2.Selected the hole transport layer material to optimize the carrier balance of the device. Using poly-TPD with a more matching band structure and hole transport rate as the hole transport.The luminance of the perovskite quantum dot light-emitting diodes(PQLEDs) is 92279 cd m^-2,which is one of the highest levels of green PQLEDs.3.The Al₂O₃ buffer layer with controllable thickness was deposited based on ALD technology to realize the preparation of high-stability PQLEDs.By growing an Al₂O₃ buffer layer on the ITO electrode,the diffusion of metal ions from ITO to PQDs is suppressed,and the stability of the device is greatly improved.