The origin of the hole injection improvements at indium tin oxide/molybdenum trioxide/ N, N′ -bis(1-naphthyl)- N, N′ -diphenyl- 1, 1′ -biphenyl- 4, 4′ -diamine interfaces

Hyunbok Lee, Sang Wan Cho, Kyul Han, Pyung Eun Jeon, Chung Nam Whang, Kwangho Jeong, Kwanghee Cho, Yeonjin Yi

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Abstract

We investigated the interfacial electronic structures of indium tin oxide (ITO)/molybdenum trioxide (MoO3) /N, N′ -bis(1-naphthyl)- N, N′ -diphenyl- 1, 1′ -biphenyl- 4, 4′ -diamine (NPB) using in situ ultraviolet and x-ray photoemission spectroscopy to understand the origin of hole injection improvements in organic light-emitting devices (OLEDs). Inserting a MoO3 layer between ITO and NPB, the hole injection barrier was remarkably reduced. Moreover, a gap state in the band gap of NPB was found which assisted the Ohmic hole injection at the interface. The hole injection barrier lowering and Ohmic injection explain why the OLED in combination with MoO3 showed improved performance.

Original languageEnglish
Article number043308
JournalApplied Physics Letters
Volume93
Issue number4
DOIs
Publication statusPublished - 2008 Aug 15

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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