"Enhancement of Efficiency of Transparent OLEDs by Reducing Surface Plasmon Loss"

Transparent display based on OLEDs is a strong candidate for pervasive displays in the near future. However, transparent OLEDs have a several weak points such as efficiency, reliability, visibility, and transparency. In particular, the efficiency of transparent OLEDs is a critical issue because light emission is going through both the top and bottom side of OLEDs. When we look into the light loss mechanism in OLEDs, surface plasmon and waveguide loss are most serious problems. In this talk, how to reduce the surface plasmon and waveguide loss is suggested and discussed. The irregular hole injection layer in transparent OLEDs was fabricated by use of colloidal lithography. The light extraction efficiency of transparent was improved due to Bragg scattering of waveguide modes and surface plasmon polaritons, and the operating voltage was also decreased. As a result, the external quantum efficiency and the power efficiency of transparent OLEDs were increased as compared with those of conventional transparent organic light emitting diodes without irregular hole injection layer. The angular dependence of emission characteristics was investigated by measuring radiant intensity profiles for emission angles and azimuthal angles.

About Professor Choi

Kyung Cheol Choi received the B.S. degree from the Department of Electrical Engineering, Seoul National University, Seoul Korea, in 1986, and the M.S. degree and Ph.D. degree in plasma engineering from Seoul National University in 1988 and 1993, respectively.

From 1993 to 1999, he was involved with researching and developing display devices at the Institute for Advanced Engineering, Spectron Corporation of America, and Hyundai Electronics Industries. From 2000 to 2004, he was an Associate Professor with the Department of Electronics Engineering, Sejong University, Seoul. He was also in charge of the Information Display Research Center supported by the Korean Ministry of Information and Communication. Since February 1, 2005, he has been with the Department of Electrical Engineering, KAIST, Daejeon, Korea, where he was first an Associate Professor and is currently a KAIST Chair Professor. Since September 2007, he has been in charge of the Center for Advanced Flexible Display Convergence supported by the Korean Ministry of Education, Science, and Technology. He has also been in charge of LG Display –KAIST Cooperation center since 2010. His research interests include flexible and transparent displays, organic light-emitting diodes, plasma display panels, and surface plasmon applications for displays.

Dr. Choi is a member of the Society for Information Display, and the Korean Information Display Society. He had been an Associate Editor of IEEE/OSA Journal of Display Technology from 2005 to 2010.

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