Electronic Resource
[S.l.]
:
American Institute of Physics (AIP)
Journal of Applied Physics
89 (2001), S. 1704-1712
ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The influence of trapped and interfacial charges on the device characteristics of organic multilayer light-emitting devices is investigated. We have studied devices consisting of 20 nm copper phthalocyanine as buffer and hole-injection layer, 50 nm N,N′-di(naphthalene-1-yl)-N,N′ diphenyl-benzidine (NPB) as hole-transport layer, and 65 nm tris(8-hydroxyquinolinato)aluminum (Alq3) as electron transport and emitting layer sandwiched between a high-work-function metal and a semitransparent Ca electrode. Current–voltage measurements show that the device characteristics in negative bias direction and at low positive bias are influenced by charges trapped within the organic layers. This is manifested by a strong dependence of the current on the direction and speed of the voltage sweep in this range. Low-frequency capacitance–voltage and static charge measurements reveal a voltage-independent capacitance in negative bias direction and a significant increase between 0 and 2 V, indicating the presence of negative interfacial charges at the NPB/Alq3 interface. Transient experiments show that the delay time of electroluminescence under forward bias conditions is controlled by the buildup of internal space charges rather than by charge-carrier transport through the organic layers. © 2001 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1332088
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