Exciplex Formations at the HTL/Alq3 Interface in an Organic Light-Emitting Diode: Influence of the Electron−Hole Recombination Zone and Electric Field

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• 作者：Naoki Matsumoto ; Chihaya Adachi
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：March 18, 2010
• 年：2010
• 卷：114
• 期：10
• 页码：4652-4658
• 全文大小：372K
• 年卷期：v.114,no.10(March 18, 2010)
• ISSN：1932-7455

文摘

In this work, we investigate the influence of weak intermolecular interactions, which have not previously been carefully considered, in hole transport material (HTM)/tris(8-hydroxyquinoline)aluminum (Alq₃)-based organic light-emitting diodes (OLEDs). Although such weak interactions quench Alq₃ fluorescence, no significant spectral shift is identified. Electroluminescence of OLEDs containing HTM:Alq₃ codeposited (mixed) emitter is quenched by the formation of such exciplexes. In general, the electroluminescence quantum efficiency of OLEDs correlates closely with the photoluminescence quantum yields of HTM:Alq₃ codeposited films. In contrast, in an OLED containing a layered structure of HTM/Alq₃, exciplexes are less effective at quenching the electroluminescence of Alq₃. Because exciplexes form only at the interface between the HTM and Alq₃ layers in HTM/Alq₃-based OLEDs, exciplex formation is affected not only by the electron donating nature of the HTM but also by the position of the electron−hole recombination zone and the application of an external electric field during OLED operation.