Jpn. J. Appl. Phys. 48 (2009) 102302 (4 pages)  |Previous Article| |Next Article|  |Table of Contents|
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Study on the Electron Injection Mechanism of Thermally Decomposable Cs₂CO₃

Qian Liu, Lian Duan, Yang Li, Juan Qiao, Zhiwu Yu, Deqiang Zhang, Liduo Wang, Guifang Dong, and Yong Qiu

(Received June 22, 2009; accepted July 21, 2009; published online October 20, 2009)

Thermally evaporated Cs₂CO₃ has been reported to be an efficient electron injection material for organic light-emitting diodes (OLEDs) although its electron injection mechanism remains under debate. In this study, we reported a thermodynamic calculation of the decomposition reactions of Cs₂CO₃, indicating that it is thermodynamically reasonable for Cs₂CO₃ to decompose into metallic Cs. A thermal decomposition experiment on Cs₂CO₃ was carried out and the decomposition temperature of Cs₂CO₃ was found to be close to the calculated temperature at which Cs₂CO₃ decomposes into metallic Cs. The in situ X-ray photoemission spectroscopy (XPS) profiles showed an agreement between the deposited Cs₂CO₃ and the standard metallic Cs. The interaction between N and Cs atoms in the Cs₂CO₃-doped tris(8-hydroxyquinoline) aluminum (Alq₃) film was verified by XPS, indicating the existence of Cs. The effect of the oxidizing atmosphere on the electron-only devices has been investigated, and the thermal decomposition of Cs₂CO₃ into metallic Cs was further confirmed.

URL: http://jjap.jsap.jp/link?JJAP/48/102302/
DOI: 10.1143/JJAP.48.102302

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