Strong interfacial dipole formation with thermal evaporation of lithium cobalt oxide for efficient electron injections

Hyunbok Lee, Soohyung Park, Jeihyun Lee, Younjoo Lee, Dongguen Shin, Kwangho Jeong, Yeonjin Yi

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

We investigated the electronic structures at the interface of Al/lithium cobalt oxide (LiCoO2)/tris(8-hydoxyquinoline) aluminum (Alq 3) to elucidate the origin of the electron injection enhancement with the insertion of the LiCoO2 layer in organic light-emitting devices using in situ photoelectron spectroscopy experiments. We discovered that LiCoO2 was decomposed into lithium oxide (Li2O) by thermal evaporation, and only Li2O was deposited on the desired substrate. Li2O forms a strong interfacial dipole, which reduces the surface potential on Alq3 due to its extremely low work function. As a result, the electron injection barrier was dramatically decreased by the Li 2O layer. Furthermore, there is no strong chemical interaction at the interface of Al/Li2O/Alq3; hence, this would contribute to extend the device lifetime.

Original languageEnglish
Article number033302
JournalApplied Physics Letters
Volume102
Issue number3
DOIs
Publication statusPublished - 2013 Jan 21

Bibliographical note

Funding Information:
This work was supported by the Yonsei University Research Fund of 2012 and Samsung Display Company, a research project of the National Research Foundation of Korea (Grant No. 2012-0002303).

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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