Interfacial electronic structure of N, N′ -bis(1-naphthyl)- N, N′ -diphenyl-1, 1′ -biphenyl-4, 4′ -diamine/copper phthalocyanine: C60 composite/Au studied by ultraviolet photoemission spectroscopy

Sang Wan Cho, Kyung Hwa Yoo, Kwangho Jeong, Chung Nam Whang, Yeonjin Yi, Myungkeun Noh

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Abstract

The interfacial electronic structures of N, N′ -bis(1-naphthyl)- N, N′ -diphenyl-1, 1′ -biphenyl-4, 4′ -diamine (NPB)/copper phthalocyanine (CuPc) Au, NPB C60 Au, and NPBCuPc: C60 composite/Au were investigated by in situ ultraviolet photoelectron spectroscopy to understand the highly efficient hole injection in organic light-emitting diode. The hole-injection barrier of CuPc: C60 Au was 0.52 eV, while those of CuPcAu and C60 Au were 0.96 and 1.62 eV, respectively. The lowered injection barrier is attributed to the smaller interface dipole of CuPc: C60 compared to that of pristine CuPc. This small interface dipole pulled up the highest occupied molecular orbital of CuPc in composite, which results in the decreased hole-injection barrier.

Original languageEnglish
Article number052102
JournalApplied Physics Letters
Volume91
Issue number5
DOIs
Publication statusPublished - 2007 Aug 10

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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