OLED began to challenge mainstream display technology

Liquid crystal display (LCD) and plasma display (PDP) is the mainstream technology of today's TV screen, at the same time, LCD is almost the first choice for any application. However, there are two kinds of emerging technologies, eager to challenge its dominance of the organic light emitting diode (OLED) recently on the market and electronic paper (e-paper). OLED has long been among the portable display market, and may enter the family as a new TV display technology. At the same time, the paper also cannibalizing the portable electronic equipment, consumer electronics and electronic label and other special needs low power consumption and longer battery life market. Recently held in Tokyo, the 2008 display technology conference, E Ink, Fujitsu (Fujitsu) and Bridgestone and other companies were on display in the light, thin and power-saving electronic paper display the latest developments. Sony displays a 0.3mm thick OLED display prototype, which is commonly referred to as' organic electroluminescent '(OEL) displays in asia. The new 1.4mm than Sony in December last year for its OLED TV display XEL-1 OLED panel design is also more lightweight. Sony also exhibited the thinnest OLED prototype, with a thickness of only 0.2mm. In addition, the company also unveiled a 27 inch OLED TV display, can display high resolution video image of 1920 * 1080 pixel format. The target market for electronic paper is handheld rather than television, most of the electronic paper is bistable, that is, even if the power is turned off, you can keep the contents of the screen without power supply. Electronic paper is a reflective display, it does not need to conduct a LCD display backlight, also need not OLED light-emitting mechanism, therefore, electronic paper is very suitable for low power applications. Not only the strengths of both light and thin OLED display, OLED display screen size up to 30 inch (diagonal), and there are many suitable for TV screen with other properties, including beyond the NTSC specifications of the color reproduction, and rapid response time is only about a few microseconds. Its maximum brightness is more than 1000cd/m2, the contrast is greater than 10000:1. OLED war Samsung has joined the war OLED. "We will produce 40 or 42 inch TVs using OEL panels before 2010. Samsung SDI mobile display vice president of marketing department Lee Woo Jong said. In addition, Samsung will also be in the end of this year for the production of notebook computers 14 inch OLED panel. Display panel manufacturers odd crystal Optoelectronics (CMEL) also eyeing the OLED. The company will use a 12.1 inch OEL screen notebook computer in the production during the first half of the business in 2009, and plans in the second half of next year for mass production of 32 inch panel TV, the company vice president Park Sung Soo said. Although considerable progress has been made in this field, there are still many problems in the application of OEL technology to larger panels. The OLED panel is made of a thin film transistor (TFT) that is polymerized on a glass substrate, which is then injected into a series of organic layers to transport and recombine electrons and holes. For the production of larger panels, it is no longer possible to use the manufacturing technology of thin film transistors or light-emitting layers that were originally made for small OLED panels. For example, in the development of 11 inches of the first OLED TV XEL-1, Sony using low temperature polysilicon (LTP) technology as the substrate of TFT, and small molecular materials as organic film. But in the 27 inch OLED prototype, Sony engineers used the advanced ceramics' '(microcrystal) thin silicon transistor technology, and introduced a Sony called'laser-induced pattern-wise sublimation (LIPWS) laser transfer printing technology. Yoshi Ishibashi, technical director of the Sony process, explains that there are currently three production processes for TFT - laser annealing, direct deposition and solid phase growth. "We think that for large panels, laser annealing is the best option for the crystallization of silicon. He said. Although the electron mobility of microcrystalline silicon is inferior to that of polycrystalline silicon, it has another important advantage, Ishibashi pointed out, that is, in the manufacture of large size substrate, the planar uniformity of microcrystalline silicon is very high. The industry has yet to find the best way to make organic films. In the Sony XEL-1 products, from organic materials in the furnace of evaporation in RGB pixel position by vapor deposition, it must immediately below the substrate in placing the metal mask. However, when the substrate is more than a certain size, the metal mask will be deformed due to its own weight, or heat radiation from the furnace, resulting in positioning error, reducing the aperture ratio (aperture ratio) and resolution. So, Sony's engineering team is looking for another technology for the development of its 27 inch prototype. For the combination of white OEL materials and color filters, laser annealing technology still has its appeal. "Ishibashi says. The color filter can achieve ultra high density, the reason is you don't need to use the mask to form a red, green and blue sub-pixel independent pattern. As a result, it may reduce the color purity and increase power consumption, but can reduce manufacturing costs. Has nothing to do with the panel size, the number of pixels' dead 'will not change. So, we must try to avoid the factors leading to dead pixel. "In order to achieve this goal, the use of white OEL materials and color filters is the best way to achieve this goal," said Takatoshi Tsujimura, senior director of Kodak's OLED products division. "Sujimura is introduced through the method in the traditional RGB color sub pixels arranged on a white pixel, can improve the luminous efficiency of two times. "This is because white pixel without using the color filter, so," he said. "Therefore, there is no effect of white light emission 100% obstacles, this is the reason it was able to achieve high luminous efficiency. "Lighting applications in addition to