Nowadays, as the information society advances dramatically and electronic devices are required to carry out ever more sophisticated functions, electronic displays are growing in importance and act as the interface to our lives.
At the OLED Business Unit of Tohoku Pioneer we have been developing and manufacturing a new type of display device, the organic light emitting diode (OLED) display, which meets the stringent requirements of this new age. OLED displays have many excellent characteristics, including sharp, bright graphics, a wide viewing angle, low power consumption and fast response as well as being extremely thin.
Pioneer Corporation early focused its attention on the practical applications of OLED, which was introduced by C.W. Tang's study group in 1987, and made an early start in OLED research and development. By 1997 Tohoku Pioneer had succeeded in the world's first mass production of OLED displays. Since then Tohoku Pioneer has expanded its OLED display market into cellular phones, Pioneer's in-car audio systems as well as various other applications. Tohoku Pioneer will use this accumulated experience, expertise and technology to provide our customers with the most advanced, high value OLED displays.
OLED displays are new-generation displays utilizing organic compounds and having self-emissive characteristics.
OLED displays produce higher contrast images, have a wider viewing angle, faster response and are thinner and more lightweight compared to conventional displays.
Working Principle of OLED
OLED has a simple structure, which has an organic light emitting layer between anodes and cathodes.
When a direct current is applied to the device, holes with positive charges are injected from anodes and electrons with negative charges are injected from cathodes into the organic light emitting layer. Then, the organic molecules emit light when the positive hole and the negative electron couple and generate energy in the organic light emitting layer.
Because most of the organic materials are isolators and are difficult to conduct current, organic light emitting layers need to have very thin structures, approximately 0.1um.
Device Structure of OLED
The typical device structure of OLED is a laminated anode (transparent electrode), a hole injection layer, a hole transport layer, an emitting layer, an electron transport layer, an electron injection layer and a cathode (metal electrode) on the glass substrate. Each layer is stacked on the glass substrate using vacuum deposition technology. Because organic materials are affected by oxygen and moisture, OLED panels are encapsulated by sealing materials such as metal or glass after being produced into layers on the glass substrate.