Recently,perovskite light-emitting diodes(PeLEDs)have shown excellent properties such as ultra-high color purity,ultra-wide color gamut,and high luminous efficiency.In particular,the external quantum efficiency(EQE)and brightness of green and near-infrared light PeLEDs had been rapidly improved,but the performance(effi-ciency,brightness,reliability,etc.)of pure-red PeLEDs with emission peak at 620-640 nm developed relatively slowly.In this paper,the pure-red mixed halogen perovskite CsPb(Br/I)3 nanocrystals were successfully prepared by a traditional hot injection combined with post-treatment process based on N-hydroxyethyl ethylenediamine triacetic acid(HEDTA)ligands.The optical properties and stability were significantly improved.HEDTA multi-dentate li-gands effectively bound to Pb2+and I-on the surface of nanocrystals to passivate the surface defects related to Pb2+ions,and at the same time,inhibited the formation of I-Frankel defects that usually lead to halide segregation.Final-ly,PeLEDs encapsulated with HEDTA treated CsPb(Br/I)3 nanocrystals as a luminescent layer achieved a pure-red emission peaked at 636 nm as well as a maximum EQE and luminnace of 18.62%and 1 880 cd/m2,respectively.
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