Analysis of Dark Spots Growing in Organic EL Devices by Time-of-Flight Secondary Ion Mass Spectrometry

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• 作者：Atsushi Murase ; Masahiko Ishii ; Shizuo Tokito ; and Yasunori Taga
• 刊名：Analytical Chemistry
• 出版年：2001
• 出版时间：May 15, 2001
• 年：2001
• 卷：73
• 期：10
• 页码：2245 - 2253
• 全文大小：867K
• 年卷期：v.73,no.10(May 15, 2001)
• ISSN：1520-6882

文摘

Chemical structural analysis of tape-stripped surfaces atdark spots growing in organic electroluminescent (EL)devices during exposure to the atmosphere was done bytime-of-flight secondary ion mass spectrometry (TOF-SIMS). The EL devices consist of indium-tin-oxide,triphenylamine-tetramer, tris(8-hydroxyquinoline)aluminum (Alq₃), and a Mg-Ag cathode deposited in orderunder vacuum on a glass substrate. It was found that theinterface between the Alq₃ layer and the Mg-Ag cathodewas exposed as a result of tape-stripping, where a largenumber of dark spots were observed on both sides.Secondary ion images of O^-, Mg⁺, and Alq₂⁺ were observed from the dark spots on the cathode side. On theother hand, Mg⁺ and O^- images with a nucleus in thecenter were observed from the Alq₃ side. It is concludedfrom the results that the constituent element Mg of thecathode was oxidized at the interface adjacent to the Alq₃layer during exposure to the atmosphere, forming a darkspot with a nucleus in the center. Finally, it was confirmedthat the TOF-SIMS analysis of the tape-stripped surfaceis useful for the analysis of the mechanism of dark spotformation.