Electronic structure of anode interface with molybdenum oxide buffer layer

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• 作者：Kaname Kanai ; Kenji Koizumi ; Satoru Ouchi ; Yoshiaki Tsukamoto ; Kei Sakanoue ; Yukio Ouchi ; Kazuhiko Seki
• 关键词：MoO₃ ; Oxygen vacancy ; Ultraviolet photoemission spectroscopy ; Inverse photoemission spectroscopy
• 刊名：Organic Electronics
• 出版年：2010
• 出版时间：February 2010
• 年：2010
• 卷：11
• 期：2
• 页码：188-194
• 全文大小：576 K

文摘

The electronic structure at the α-NPD/MoO₃/Au interfaces has been investigated with ultraviolet photoemission spectroscopy (UPS), X-ray photoemission spectroscopy (XPS) and inverse photoemission spectroscopy (IPES). It was found that the MoO₃ layer contains some number of oxygen vacancies prior to any treatment and gap states are induced by the partial filling of the unoccupied 4d orbitals of molybdenum atoms neighboring oxygen vacancies. The α-NPD thickness dependence of XPS spectra for the α-NPD/MoO₃ system clearly showed that molybdenum atoms at the surface of the MoO₃ film were reduced by α-NPD deposition through the charge-transfer interaction between the adsorbed α-NPD and the molybdenum atoms. This reduction at the α-NPD/MoO₃ interface formed a large interface dipole layer up to −1.79 eV. The deduced energy-level diagram for the α-NPD/MoO₃/Au interfaces describes the energy-level matching that explains well the significant reduction in the hole-injection barrier due to the MoO₃ buffer layer.