文献类型：期刊文献

中文题名：热蒸发法制备以有机小分子-无机钙钛矿复合薄膜为发光层的白光PeLED

英文题名：White PeLED with the composite emission layer of organic small molecule and perovskite materials prepared by thermal evaporation

作者：肖双[1];罗有华[1];牟海川[1];王瑞斌[2];贾钧麟[1]

机构：[1]华东理工大学物理学院,上海200237;[2]上海交通大学分析测试中心,上海200240

年份：2022

卷号：67

期号：2

起止页码：193

中文期刊名：科学通报

外文期刊名：Chinese Science Bulletin

收录：CSTPCD;;EI(收录号：20220611595919);Scopus;WOS:【ESCI(收录号:WOS:000754428500009)】；北大核心:【北大核心2020】；CSCD:【CSCD2021_2022】；

语种：中文

中文关键词：白光钙钛矿发光二极管;电致发光;钝化;热蒸发法

外文关键词：white PeLED;electroluminescence;passivation;thermal evaporation

摘要：近年来,金属卤化物钙钛矿发光器件(PeLED)的研究取得了很多突破,其电致发光(electroluminescence,EL)性能得到了很大提高,但关于白光PeLED的报道较少.本文报道了用真空热蒸发法制备结构为ITO/MoO;/TAPC/TCTA/CsPbBr_(3)/mCP/TmPyPB/LiF/Al的白光PeLED器件,其中CsPbBr_(3)/mCP作为发光层.扫描电子显微镜和X射线衍射测试结果证明,热蒸发法可制得微米级尺寸的钙钛矿晶粒,并且钙钛矿薄膜晶粒的择优生长取向为(100)晶面.研究发现,有机小分子材料mCP对钙钛矿薄膜有钝化作用,可用于改善发光层的成膜性,减小陷阱密度;并且陷阱密度随着mCP膜厚增加而减少.此外,mCP膜厚对白光中不同光色的比例和载流子复合区域的移动也有影响.当CsPbBr_(3)膜厚为20 nm、mCP膜厚为10~30 nm时可得到白光PeLED.其中,当mCP膜厚为20 nm时,由于蓝、绿、红光比例最均衡,所获得的白光质量最好,其器件的显色指数最高达到89,最优色坐标则为(0.33,0.34);当mCP膜厚为30 nm时器件EL性能最好,其最大电流效率、亮度、外量子效率和显色指数分别可达0.35 cd/A、341 cd/m^(2),0.42%和82.可见白光PeLED的EL性能随mCP增厚而提高(10~30 nm).对稳态光致发光光谱的研究表明,波长为380 nm的蓝紫光、620 nm的红光来自mCP,而波长为520 nm的绿光来自CsPbBr_(3).该白光PeLED器件白光质量高,且结构简单,具有一定的应用价值.
Metal halide perovskite material has received considerable attention in recent years because of its unique properties, such as high photoluminescence quantum yield, adjustable bandgap, high carrier mobility, and long diffusion length, which provide promising research and application potential in the following optoelectronic fields: Photovoltaic, light-emitting diode, and photodetector. By improving emission layer morphology and structure quality as well as controlling emission materials’ dimensional size, the external quantum efficiency(EQE) of the sole color light-emitting Pe LED has already been over 20%, which is comparable to the performance of the optimal organic light-emitting diode. However, the development of Pe LED still faces serious challenges, such as poor temperature, long-term stability, and hard reproducibility of the fabrication. However, metal halide Pe LED demonstrates superior stability compared with routine hybrid Pe LED owing to the replacement of organic cations like MA;and FA;at the A site of the ABX;molecular structure by monovalent metal cations such as Cs;, Ag;, and Na;, which provides a promising substitute to the routine hybrid Pe LED.There are few reports regarding Pe LED fabrication using physical vapor deposition methods such as thermal evaporation, which can be attributed to its typically higher cost and lower light-emitting efficiency. However, the thermal evaporation procedure has distinct advantages, such as precise control of the element content and layer thickness, which is especially important for achieving a superthin layer.In this study, the fabrication and EL performance of the white Pe LED with the structure of ITO/MoO;/TAPC/TCTA/CsPbBr_(3)/mCP/Tm Py Pb/Li F/Al have been investigated, in which the CsPbBr_(3)/mCP is employed as emission layer.Consequently, all functional layers are fabricated through thermal evaporation, while the CsPbBr_(3)layer is formed through the dual-source coevaporation of Cs Br and PbBr;.The passivation effects of the organic small molecule material mCP on the perovskite emitter are observed with considerably reduced trap densities in the emission layer. Meanwhile, as the mCP thickness increases, the trap density decreases. Furthermore, the thickness of the mCP strongly affects the ratio of the different emitting colors in white light and the shifting of the exciton recombination zone. Therefore, the white Pe LED can be realized while the thicknesses of CsPbBr_(3)and mCP are kept at 20 nm and within ~10–30 nm, respectively, in which the 20-nm mCP will yield the highest quality white light with the highest color rending index(CRI) of 89 and optimal CIE coordinates of(0.33, 0.34) due to the balanced emission of blue, green, and red light. The optimal EL performance can be obtained at the mCP thickness of 30 nm, with the maximum current efficiency, brightness, EQE, and CRI of 0.35 cd/A, 341 cd/m^(2), 0.42%, and 82,respectively. Therefore, the improvement of the EL performance with the increasing mCP layers thickness(~10–30 nm)can be demonstrated. The blue-purple and red light at 380 and 620-nm wavelengths are attributed to the mCP, whereas the green light at 520 nm is attributed to CsPbBr_(3). The research demonstrates a practical method for developing white Pe LEDs with high-quality white light emission and a simple structure.