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Enhanced Hole Injections in Organic Light Emitting Diode using Rhodium Oxide Coated Anode  

Kim, Soo-Young (Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH))
Choi, Ho-Won (Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH))
Kim, Kwang-Young (Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH))
Tak, Yoon-Heung (LG Electronics Inc.)
Lee, Jong-Lam (Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH))
Publication Information
JSTS:Journal of Semiconductor Technology and Science / v.5, no.2, 2005 , pp. 77-82 More about this Journal
Abstract
We compare electrical and optical properties of organic light emitting diodes (OLEDs) using rhodium-oxide-coated indium-tin-oxide ($O_2$-Rh/ITO) to that using $O_2$-plasma-treated ITO (ITO) anodes. The turn-on voltage decreased from 7 V to 5 V and luminance value increased when the $O_2$ plasma treated Rh layer was deposited on ITO. Synchrotron radiation photoelectron spectroscopy results showed the dipole energies of both ITO and $O_2$-Rh/ITO were same with each other, - 0.3 eV, meaning the formation of same amount of interface dipole. The secondary electron emission spectra revealed that the work function of $O_2$-Rh/ITO is higher hy 0.2 eV than that of ITO, resulting in the decrease of the tum-on voltage via reduction ofhole injection barrier.
Keywords
organic light emitting diodes; hole injection layer; synchrotron radiation photoemission spectroscopy; interface dipole; $O_2$ plasma treatment;
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