用于有机发光二极管的溶液处理超薄电子注入层的研究。
Investigation of solution-processed ultrathin electron injection layers for organic light-emitting diodes.
作者信息
Stolz Sebastian, Scherer Michael, Mankel Eric, Lovrinčić Robert, Schinke Janusz, Kowalsky Wolfgang, Jaegermann Wolfram, Lemmer Uli, Mechau Norman, Hernandez-Sosa Gerardo
机构信息
Light Technology Institute, Karlsruhe Institute of Technology , Engesserstrasse 13, 76131 Karlsruhe, Germany.
出版信息
ACS Appl Mater Interfaces. 2014 May 14;6(9):6616-22. doi: 10.1021/am500287y. Epub 2014 Apr 23.
We study two types of water/alcohol-soluble aliphatic amines, polyethylenimine (PEI) and polyethylenimine-ethoxylated (PEIE), for their suitability as electron injection layers in solution-processed blue fluorescent organic light-emitting diodes (OLEDs). X-ray photoelectron spectroscopy is used to determine the nominal thickness of the polymer layers while ultraviolet photoelectron spectroscopy is carried out to determine the induced work-function change of the silver cathode. The determined work-function shifts are as high as 1.5 eV for PEI and 1.3 eV for PEIE. Furthermore, atomic force microscopy images reveal that homogeneous PEI and PEIE layers are present at nominal thicknesses of about 11 nm. Finally, we solution prepare blue emitting polymer-based OLEDs using PEI/PEIE in combination with Ag as cathode layers. Luminous efficiency reaches 3 and 2.2 cd A(-1), whereas maximum luminance values are as high as 8000 and 3000 cd m(-2) for PEI and PEIE injection layers, respectively. The prepared devices show a comparable performance to Ca/Ag OLEDs and an improved shelf lifetime.
我们研究了两种水/醇溶性脂肪族胺，即聚乙烯亚胺（PEI）和乙氧基化聚乙烯亚胺（PEIE），以评估它们作为溶液处理的蓝色荧光有机发光二极管（OLED）中电子注入层的适用性。使用X射线光电子能谱来确定聚合物层的标称厚度，同时进行紫外光电子能谱以确定银阴极的诱导功函数变化。对于PEI，确定的功函数偏移高达1.5 eV，对于PEIE则为1.3 eV。此外，原子力显微镜图像显示，在约11 nm的标称厚度下存在均匀的PEI和PEIE层。最后，我们使用PEI/PEIE与Ag作为阴极层，通过溶液法制备了基于蓝色发光聚合物的OLED。对于PEI和PEIE注入层，发光效率分别达到3和2.2 cd A⁻¹，而最大亮度值分别高达8000和3000 cd m⁻²。所制备的器件表现出与Ca/Ag OLED相当的性能以及更长的储存寿命。
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