OLED Efficiency Improved

DAEJEON, South Korea, July 17, 2009 -- A research team at KAIST (Korea Advanced Institute of Science and Technology) has discovered surface plasmon-enhanced spontaneous emission based on an organic LED (OLED), a finding expected to improve the device's energy consumption, KAIST officials announced last week.

For surface plasmon localization, professor Kyung-Cheol Choi of the School of Electrical Engineering & Computer Science and his team deposited silver nanoparticles thermally in a high vacuum on cathode. Since plasmons provide a strong oscillator decay channel, time-resolved photoluminescence (PL) results displayed a 1.75-fold increased emission rate, and continuous wave PL results showed a twofold enhanced intensity.

"The method using surface plasmon represents a new technology to enhance the emission efficiency of OLED. It is expected to greatly contribute to the development of new technologies in OLED and flexible display, as well as securing original technology," Choi said.

The finding was published in the April issue of Applied Physics Letters and the June 25 issue of Optics Express and will also featured as the research highlight of the August issues of Nature Photonics and Virtual Journal of Ultrafast Science.

For more information, visit: www.kaist.edu

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Published: July 2009

Glossary

cathode: A cathode is an electrode through which electric current flows out of a polarized electrical device. In different contexts, the specific role and behavior of the cathode can vary, but it generally serves as the site for reduction reactions (gain of electrons). Reduction site: In electrochemical cells, the cathode is where reduction occurs, meaning it is the site where electrons are gained by a chemical species. Electric current direction: The direction of electric current...
efficiency: As applied to a device or machine, the ratio of total power input to the usable power output of the device.
photoluminescence: Photoluminescence is a phenomenon in which a material absorbs photons (light) at one wavelength and then re-emits photons at a longer wavelength. This process occurs when electrons in the material are excited to higher energy states by absorbing photons and subsequently return to lower energy states, emitting photons in the process. The emitted photons have less energy and longer wavelengths than the absorbed photons. Photoluminescence can be broadly categorized into two types: ...
photonics: The technology of generating and harnessing light and other forms of radiant energy whose quantum unit is the photon. The science includes light emission, transmission, deflection, amplification and detection by optical components and instruments, lasers and other light sources, fiber optics, electro-optical instrumentation, related hardware and electronics, and sophisticated systems. The range of applications of photonics extends from energy generation to detection to communications and...
vacuum: In optics, the term vacuum typically refers to a space devoid of matter, including air and other gases. However, in practical terms, achieving a perfect vacuum, where there is absolutely no matter present, is extremely difficult and often not necessary for optical experiments. In the context of optics, vacuum is commonly used to describe optical systems or components that are operated in a low-pressure environment, typically below atmospheric pressure. This is done to minimize the effects...

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