Study On Performance Enhancement Of Inorganic Perovskite Quantum Dots Light-Emitting Diodes By Defect Passivation

Metal halide perovskite quantum dots（PeQDs）,as an emerging material,has attracted wide attention due to its good performance,such as low manufacturing cost,high absorption coefficient,wide color gamut and narrow full width at half maxima and tunable emission spectra to cover full visible spectrum.For the next generation light-emitting diode（LED）,PeQDs,owing to amazing performance,is the most promising material,while it has poor stability due to its ionic characteristics in present.In addition,due to the large number of organic ligands required to synthesize PeQDs and to maintain the light emission of PeQDs,the performance of PeQLED based on PeQDs is unalluring,owing to lost in the process of PeQLED preparation and insulation for traditional organic ligands.Third,PeQLED performance is also affected by injection barrier,and a large injection barrier will lead to a decline in PeQLED performance.Our research focuses on improving the performance of PeQLED,through the passivation of PeQDs and PeQLED interface.Specific research includes the following three aspects:1,The ZnBr₂ was used,passivating Cs Pb Br₃ QDs surface to improve the light emitting efficiency and stability.The light emission efficiency and stability of PeQDs were improved,owing to ZnBr₂ being dispersed in EA as an inorganic ligand to inhibiting the formation of vacancy defects of Pb²⁺and Br^-.The PeQLED based on the Cs Pb Br₃ QDs with ZnBr₂ exhibited a maximum luminance of 96392 cd m^-2,current efficiency（CE）of 21.1 cd A^-1and external quantum efficiency（EQE）of 6.43%.Compared with the PeQLED from PeQDs without passivation,the enhancement of maximum luminance and EQE is up to 200%and 100%.This work provides a simple and effective strategy to passivate the surface vacancy defects of Cs Pb Br₃ QDs.2,The PeQLED light emitting efficiency was improved by introducing ZnBr₂passivation bottom interface of PeQDs emitting layer.The light emission performance of PeQLED was improved,due to the defects being effectively reduced in the film forming process of Cs Pb Br₃ QDs though ZnBr₂ interface passivation.The PeQLED based on ZnBr₂ as the base interface exhibited a maximum luminance,CE and EQE were 56148 cd m^-2,32.65 cd A^-1 and 10.51%,respectively.Compared with unpassivated PeQLED,the enhancement of maximum luminance and EQE is up to 16%and 118%.3,The PeQLED light emitting efficiency was improved,by introducing PFN as the interface modification layer under the emitting layer.The Cs Pb Br₃ QDs layer defects were passivated when the PFN modification layer was introduced between the PEDOT:PSS and the emitting layer,and the hole injection barrier between the PEDOT:PSS and the Cs Pb Br₃ QDs was reduced by the bottom interface modification.As a result,the maximum luminance,EQE and CE for the PFN-modified Cs Pb Br₃QLED were 10150 cd m^-2,3.25%and 10.2 cd A^-1,corresponding to the improvement factors of 98%,322%and 336%,respectively,improvement compared to those of the devices without the PFN modification.