Direct observation of structural changes in organic light emitting devices during degradation

被引:98
作者
Kolosov, D
English, DS
Bulovic, V
Barbara, PF
Forrest, SR
Thompson, ME [1 ]
机构
[1] Univ So Calif, Dept Chem, Los Angeles, CA 90089 USA
[2] Univ Texas, Dept Chem, Austin, TX 78712 USA
[3] Princeton Univ, Dept Elect Engn, Princeton, NJ 08544 USA
关键词
D O I
10.1063/1.1389760
中图分类号
O59 [应用物理学];
学科分类号
摘要
A method for studying the degradation of organic light emitting devices (OLEDs) in real time is described. Transparent OLEDs allow for the spatial correlation of cathode topographic images with optical images (transmission, photoluminescence, and electroluminescence) of the devices throughout the degradation process. In this study we focused on the evolution of nonemissive, "dark" spots during device operation. We conclude that the electroluminescent dark spots originate as nonconductive regions at the cathode/organic interface and expand or grow as a result of exposure to atmosphere. We propose a mechanism of dark spot growth involving aerobic oxidation of the cathode/organic interfacial region, leading to a highly resistive, carrier blocking interface at the dark spot locations. No initial defects on the cathode surface, which might be responsible for the formation of dark spots, were detected by atomic force microscopy. Structural changes, such as degradation of organic materials and the cathode surface, occur well after the formation and growth of the dark spots. (C) 2001 American Institute of Physics.
引用
收藏
页码:3242 / 3247
页数:6
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