Showa Denko Develops OLED Device w/ 40% Light Extraction Efficiency

Jul 29, 2009 16:44 Megumi Yoshizawa, Nikkei Microdevices

Showa Denko K.K. used a coating process to develop a phosphorescent polymer organic EL device whose light extraction efficiency was enhanced to 40% by employing a new device structure.

The luminance efficiency of the device is 30lm/W, which the company claims is the world's highest level efficiency for an organic EL device made by a coating process.

When an organic EL device is made by coating a polymer material, a vacuum process is not required and only a few layers are needed. Therefore, it can cut costs by increasing the size of luminescent panels or their productivity in the future.

The new phosphorescent polymer organic EL device uses a dielectric layer to adjust light reflection in the structures of the negative electrode, luminescent layer, positive electrode and glass substrate, reducing the amount of light captured in the device. As a result, the light extraction efficiency was improved, enhancing the luminance efficiency.

Furthermore, the excellent radiation performance of a dielectric layer prevents heat deterioration of the luminescent layer and contributes to extending the life of the device.

Showa Denko plans to advance the development of the organic EL device by making improvements to the device structure in cooperation with SRI International, a US-based independent nonprofit research institute, and Itochu Plastics Inc. Showa Denko intends to launch samples in the lighting market in 2010.

The company has already developed a white organic EL device with a luminance half life of about 10,000 hours. And it plans to further extend the life of the device and enhance the coating performance of the phosphorescent material by utilizing the latest research achievements. Its goal is to achieve a luminance efficiency of 150lm/W and to develop a white organic EL device with a luminance half life of 50,000 hours.

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