基于HEDTA配体修饰的纯红色CsPb(Br/I)_(3)钙钛矿发光二极管

Pure Red Lead-based Perovskite Light-emitting Diodes Modified with HEDTA Ligands

近年来,钙钛矿发光二极管(Perovskite light-emitting diodes,PeLEDs)已表现出了超高色纯度、超宽色域、高发光效率等一系列卓越性能,尤其绿光和近红外光PeLEDs的外量子效率(External quantum efficiency,EQE)和亮度迅速提升,但荧光峰位于620~640 nm的纯红光PeLEDs器件的性能(效率、亮度、可靠性等)发展则相对缓慢。本文采用热注射和N-羟乙基乙二胺三乙酸(HEDTA)配体后处理相结合的工艺制备了光学性能和稳定性均显著提升的纯红色混合卤素钙钛矿CsPb(Br/I)_(3)纳米晶。HEDTA多齿配体通过与纳米晶表面的Pb^(2+)和I-有效结合,钝化表面Pb^(2+)有关的缺陷,同时抑制了致使卤化物偏析的I-弗伦克尔缺陷的形成。基于配体交换处理后的CsPb(Br/I)_(3)纳米晶为发光层制备的PeLEDs,发射峰位于636 nm的纯红色范围,最大EQE和最大亮度分别为18.62%和1880 cd/m^(2)。表征器件工作稳定性的T50(器件亮度衰减至初始亮度一半所需的时间)由未修饰器件的11.4 min提升至74.5 min。

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 Pb^(2+)and I-on the surface of nanocrystals to passivate the surface defects related to Pb^(2+)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 1880 cd/m^(2),respectively.