National Chiao Tung University professor Chen Jinxin OLED from the future to a bright future

Photoelectric News Network: the current situation of the development of the Taiwan OLED?

Chen Jinxin: Taiwan's OLED industry after eight or nine years of development, along the way is not easy, the current technology in Taiwan has a certain advantage. Recently, due to the economic downturn, some companies take a wait-and-see attitude, before a few passive to engage with vigour and vitality, now only insist on leybold.

Photoelectric News Network: OLED technical difficulties in where?

Chen Jinxin: the current OLED towards the initiative, the initiative is mainly used in thin film transistor (TFT), the current TFT industry in Taiwan has a great advantage. Now OLED technology itself is no problem, the problem is mainly driven. Active OLED used by the TFT has two main functions: one is the switching function, the other is to control the density of the injected current. The brightness of the OLED is proportional to the density of the current, so the current control should be very stable, a slight change, the brightness of the OLED will change, change 3% to 5%, people can feel out. Engage in active OLED (AMOLED), the general liquid crystal TFT can not be used, because it is amorphous TFT, amorphous silicon atoms are stacked is not arranged, and ultimately affect the mobility of electrons. How to turn amorphous TFT into crystalline TFT? Laser scanning is usually used, you can instantly melt the silicon, and then slowly cooling, crystallization, annealing, so you can turn the amorphous TFT into polycrystalline TFT. Polycrystalline TFT in the local region of the orderly arrangement of the combination, the electron mobility is greatly improved, can be increased by ten times to one hundred times, with such a high mobility, color is no problem. Now the problem is to achieve the integration of TFT and OLED, the process of the system, there are some problems in the intermediate link. In the realization of a large area of OLED when the electron density is affected, the current density will affect the brightness, 3%-5% changes, the naked eye will feel. In order to overcome this difficulty only to increase the thin film transistor (TFT), to compensate for the electron density, and ultimately achieve uniformity. However, the problem is that, after the increase in thin film transistors, the light output of the screen has declined, because the thin film transistor to block some of the light. The original 2 thin film transistors, now into the 4 or even the 6, out of light from the rate of 50%, down to 20%, in order to solve this problem, the next to the top of the light-emitting light-emitting, Taiwan called on the light. In the past, the cathode in the above, the anode in the glass, the light from the bottom up a little problem is not, and now the light from the top down there is a problem, the cathode must be done very thin, thin to about 10nm. Can be achieved after a very thin translucent, but it can not be made as fully transparent as glass. Very thin, there are two problems: one is very difficult to do, and the other is the yield of the product is greatly reduced, the process window becomes narrower. Due to the semi transparent, part of the light transmission, part of the reflection, the interference between the anode and the cathode will be formed, the formation of optical resonance cavity. Now create a new discipline called OLED optics, solve the problems in OLED optical design, optical element is a certain difficulty, to make RGB full color words, because the wavelength of RGB is not the same, the device structure will become quite complex. To sum up is to take the top light, the yield is difficult to control, the process window becomes smaller, prone to substandard goods, the price becomes expensive.

Photo news: what advice do you have for the OLED industry in mainland China?

Chen Jinxin: for the mainland OLED, I think you can focus on OLED lighting. I hope the mainland government to pay attention to this point, is now the energy crisis, although the recent decline in oil prices of some, but sooner or later will rise up, Chinese population so much, in a stage of rapid development, the major significance of the popularity of OLED. Mainland development OLED words, there are several major problems to face, one is the mainland has not TFT industry. Taiwan TFT industry is well developed now, but it was ten years ago, hundreds of billions of dollars down the results, in this regard, the mainland behind too much. Japan's ten generation plant to ship next year, South Korea is also the eight generation plant, but the mainland is still building the plant of the five or six generation.

If you engage in OLED lighting, then, do not need TFT, you can directly show the advantages of OLED. OLED is the only surface light source, there is a concept of English, Chinese does not have the corresponding words, I can explain. For example, reading, point light source is more divergent, really fall on the book is not much, and the surface of the light emitting OLED fall on the book on a lot of light, in terms of the utilization of light greatly improved. OLED lights can also be flexible display, not necessarily flat, you can use a number of special occasions. At present, the efficiency of the bulb is too low, the mercury inside the fluorescent tube, pollute the environment, will gradually eliminate. Japan has announced the elimination of incandescent lamps in 2010, Taiwan is also ready to use incandescent in 2012. More promising lighting is mainly LED lights and OLED lighting.

Photoelectric News Network: OLED lighting compared with LED what are the advantages and disadvantages?

Chen Jinxin: LED technology is relatively early development of the industry is relatively perfect, the current Taiwan is not only a chip factory, packaging plant is also thirty or forty. Some time ago was very lively, in the opening ceremony of the Olympic Games, LED was a show of Zhang Yimou, famous. In fact, LED lighting still have shortcomings, the blue chip high luminous efficiency is very expensive, as the temperature rises sharply, if indoor use, often to put the fan, then some outdoor heat, did not solve the problem will affect the life of. If you want to make LED surface light source, there are many problems