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Proceedings Paper

Mechanism of hole accumulation at Α-NPD/Alq3 interface studied by displacement current measurement
Author(s): Naoki Sato; Yutaka Noguchi; Yuya Tanaka; Yasuo Nakayama; Hisao Ishii
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Paper Abstract

We examined the driving mechanism of indium-tin oxide (ITO)/4,4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD)/Tris-(8-hydroxiquinolate) aluminum (Alq3)/cathode type organic light-emitting diode (OLED) by using a displacement current measurement (DCM). The DCM enables us to directly calculate the amount of accumulated charge. There exists a maximum value in the amounts of the blocked holes at α-NPD/Alq3 interface. The maximum value was about 120 nC/cm2, this value is consistent with the density of the fixed interfacial charge proposed by Brütting et al. By using hole-only device with Au cathode, we also investigated the hole blocking and the subsequent overflow of hole current beyond the interface. The observed feature can be explained by the hole blocking due to the interfacial charge rather than by that due to the HOMO mismatch at the interface.

Paper Details

Date Published: 2 September 2008
PDF: 7 pages
Proc. SPIE 7051, Organic Light Emitting Materials and Devices XII, 70511S (2 September 2008); doi: 10.1117/12.795790
Show Author Affiliations
Naoki Sato, Chiba Univ. (Japan)
Yutaka Noguchi, Chiba Univ. (Japan)
Yuya Tanaka, Chiba Univ. (Japan)
Yasuo Nakayama, Chiba Univ. (Japan)
Hisao Ishii, Chiba Univ. (Japan)

Published in SPIE Proceedings Vol. 7051:
Organic Light Emitting Materials and Devices XII
Franky So; Chihaya Adachi, Editor(s)

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