基于激子阻挡层的高效率绿光钙钛矿电致发光二极管  

High efficiency green perovskite light-emitting diodes based on exciton blocking layer

作　　者：王润 贾亚兰 张月 马兴娟[1] 徐强 朱志新 邓艳红[2] 熊祖洪[1] 高春红[1,2] Wang Run;Jia Ya-Lan;Zhang Yue;Ma Xing-Juan;Xu Qiang;Zhu Zhi-Xin;Deng Yan-Hong;Xiong Zu-Hong;Gao Chun-Hong(School of Physical Science and Technology,Southwest University,Chongqing 400715,China;Applied Basic Research Base of Optoelectronic Information Technology of Hunan Province,Hengyang Normal University,Hengyang 421002,China)

机构地区：[1]西南大学物理科学与技术学院,重庆400715 [2]衡阳师范学院,光电信息技术湖南省应用基础研究基地,衡阳421002

出　　处：《物理学报》2020年第3期289-298,共10页Acta Physica Sinica

基　　金：重庆市研究生科研创新项目(批准号:CYS19095);光电信息技术湖南省应用基础研究基地开放基金(批准号:GD19K01);中央高校基本科研业务费专项资金(批准号:XDJK2018C082);国家留学基金资助出国西部地区人才培养特别项目(批准号:留金项[2018]10006号);西南大学大学生创新创业训练计划(批准号:X201910635332);湖南省自然科学青年基金(批准号:2018JJ3010);衡阳师范学院英才支持计划资助的课题~~

摘　　要：金属卤化物钙钛矿材料由于具有高的光致发光量子产率、高色纯度、带隙可调等杰出的光学性能,被作为发光材料广泛地用于制备钙钛矿电致发光二极管(perovskite light-emitting diodes,PeLEDs).虽然取得了较好的研究进展,但是其效率和稳定性还未达到商业化的要求,还需要进一步提高.为了提高PeLEDs的效率和稳定性,本文使用旋涂法,引入了一种具有宽带隙和较好空穴传输能力的有机小分子材料4,4′-cyclohexylidenebis[N,N-bis(p-tolyl)aniline](TAPC)作为激子阻挡层,获得了效率和寿命都得到提高的全无机PeLEDs.研究表明,PeLEDs效率和寿命得到提高的物理机制主要源于两方面:1)TAPC具有恰当的最高占有分子轨道能级,与PEDOT:PSS的最高占有分子轨道能级和CsPbBr3的价带边形成了阶梯式能级分布,有利于空穴注入和传输;同时TAPC具有较高的最低未占分子轨道能级,能够有效地阻止电子泄漏到阳极端,并能很好地将电子和激子限制在发光层内;2)TAPC层的引入可以避免钙钛矿发光层与强酸性的空穴注入材料Poly(3,4-ethylenedioxythiophene):poly(p-styrene sulfonate)(PEDOT:PSS)的直接接触,进而免除钙钛矿发光层由于与PEDOT:PSS的直接接触所导致的激子淬灭,从而提高了激子的发光辐射复合率.In recent years,metal halide perovskite materials,owing to their excellent photoelectric properties including high photoluminescence quantum yield,high color purity,tunable band gap,etc.,have been regarded as new-generation lighting sources and are widely used to fabricate perovskite light-emitting diodes(PeLEDs).Though great progresses have been made in recent years,neither the efficiency nor stability has not yet reached the requirements of commercialization.Thus,further improvement is needed.In this work,a small organic molecule material,namely 4,4'-cyclohexylidenebis[N,N-bis(p-tolyl)aniline](TAPC)with a wide bandgap and a good hole transport ability,is used as an exciton blocking layer by utilizing the spin-coating method to improve the stability and efficiency of PeLEDs.Highly efficient and stable CsPbBr3 PeLEDs are finally realized.The physical mechanism related to the improved electroluminescence performance is investigated thoroughly.Firstly,the stepped energy level alignment is formed,since the highest occupied molecular orbital energy level(HOMO)of TAPC is located between the HOMO of(3,4-ethylenedioxythiophene):poly(p-styrene sulfonate)(PEDOT:PSS)and the valence band of CsPbBr3,which is beneficial to hole injection and transport.Meanwhile,the lowest unoccupied molecular orbital level of TAPC is high enough to prevent electrons from leaking into the anode effectively and confine electrons and excitons well in the emitting layer.Secondly,the introduction of the TAPC layer can avoid the direct contact between the perovskite light emitting layer and the strong acidic layer of PEDOT:PSS,thereby eliminating the related excitons quenching,which can further increase the radiative recombination.

关 键 词：全无机卤素钙钛矿 电致发光二极管 空穴传输 激子淬灭 激子阻挡层 

分 类 号：TN383.1[电子电信—物理电子学]