| Digital broadcasting will soon be able to be viewed outdoors while on the move. A thin, lightweight flexible display that could be rolled up for easy transport would make it especially convenient to watch TV programs anytime and anywhere. As possible flexible displays, we are developing organic EL*1 displays and film displays using liquid crystal, together with driving technologies based on organic TFT*2. |
-Flexible organic EL display
The use of phosphorescent polymer materials with high luminous efficiency to form RGB pixels on a plastic film will lead to a highly efficient self-emissive flexible display device. We have improved the molecular structure of phosphorescent polymer and have attained high luminous efficiency for green and red. The luminance and device life of the latest flexible organic EL display have been improved. |
- The improved polymer molecular structure has increased luminous efficiency (improvement from our previous displays for green: from 12% to 13%, for red: from 6.7% to 11%).
- A new moisture barrier layer has extended the device life.
- The high-speed response of organic EL is suited for a moving picture display.
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This research is being jointly carried out with Showa Denko K.K., Kyodo Printing Co., Ltd., and SELVAC Corporation.
*1 EL (Electroluminescence)
*2 TFT (Thin Film Transistor) |
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- Flexible film display using liquid crystal (LC)
A polymer micro-structure (fiber and walls) can be used in a flexible LC display device using plastic film substrates. We have developed a new low-voltage operation LC film display containing nano-polymer, so that the TFT driving of the LC becomes possible.
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- Conventional polymer fiber's molecular movement is fixed so that the LC molecular orientation is kept in one direction. This restriction requires a high LC driving voltage (15 V or higher). TFT-driven operation at just a few volts has become possible through reducing the size of the polymer fiber to nanometer order.
- Ferroelectric LC with a high-speed response (1 ms or faster) is suited for a moving picture display.
- The manufacturing process uses simple printing technique and ultraviolet-ray exposure. A large display can be easily fabricated.
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| This research is being jointly carried out with Kyodo Printing Co., Ltd. |
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-Driving technology using organic TFT
The display system should not only be flexible, but also needs high luminance, high picture quality, and a long device life. Organic TFT can be used with organic EL or LC and is necessary to achieve these features. A photolithography process*3 can help to reduce the TFT size and increase the pixel number. Prototype organic TFT-driven OLED and organic TFT-driven LCD panels have been fabricated with the process. |
- The use of anodic oxidized Ta2O5 as the gate insulator*4 has made it possible to fabricate the TFT on a plastic substrate and attain a low operating voltage.
- We have developed a photolithography process suitable for a plastic substrate. It has successfully reduced the size of the organic TFT and increased pixel number of the panels.
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| This research is being jointly carried out with Victor Company of Japan . |
We will increase the luminous efficiency and device life of the organic EL display. For the flexible display using LC, we need to improve display uniformity, contrast, and its integration with organic TFT. The flexible display device will need to have high luminance, high picture quality, and long device life. We believe that we can achieve these characteristics by improving the organic TFT so it can handle a larger number of pixels and have a higher mobility.
*3 Photolithography process: a micro-device fabrication process.
*4 Gate insulator: an insulating layer between a TFT gate electrode and an electric current channel.
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