The organic electroluminescent device, we can according to the luminescent material which is divided into two types: small molecule OLED and polymer OLED (also called PLED).Their differences are mainly in the device preparing process different: small molecular device mainly adopts vacuum thermal evaporation process, polymer device using spin coating or ink jet technology.The current international OLED related patents have been more than 1400 copies, one of the most basic patent 3 items.Small molecule OLED basic patent by American Kodak company, polymer OLED patent by the British CDT (Cambridge Display Technology) and the United States of America Uniax company has.Table 1 Comparison of two kinds of organic luminescent materials.
The organic small molecule material with metal chelate and rare earth complexes as representative.In 1987 Tang C W first adopting the compound Alq3 achieve higher efficiency of organic electroluminescent devices.This kind of common substances are: Alq3, Al, MQS, Zn (Fa 5) 2, Be Bq2.The luminescent material is in the process of making difficult separation.Other performance more superior light-emitting thin film material has Perylene, Aromaticdiamine, TAD, TAP, T, AZ, TPA, TPB, TPD, TPP etc..
The discovery of small molecule organic light emitting device stability is poor, and the structure and properties of the polymer are very stable.If you want to get high brightness, high efficiency, usually used with a carrier transport layer of the multilayer structure.Before using small molecule material as a transport layer, due to the small molecular materials easily recrystallized or with the light emitting layer material to form a charge transfer complex and excited states of aggregation leads to a decline in performance, while the polymer is able to overcome these shortcomings, therefore, people gradually focus on the polymerization.
In 1990, the University of Cambridge's Friend and Burroughes et al with conjugated polymer PPV implementation of electroluminescence.Conjugated polymers are organic semiconductor, from the principle, this material more easily than inorganic semiconductor processing and manufacturing, charge transport and quantum efficiency is inferior.Organic polymer materials mainly include polyacetylene, poly thiophene and its derivatives of organic conjugated polymers.In recent years, people found in light and other properties are relatively good in the polymer, electroluminescent thin film materials are PBD, PBP, PRL, PMMA, PPV, P VCZ etc..
In foreign OLED products, investment small molecule OLED products for the Japanese and Taiwan manufacturers; and into polymer OLED product is in Europe and the United States manufacturer is in the majority.According to statistics the world has about 85 firms R & D investment, of which more than 60 manufacturers are using small molecule OLED material system, only about 25 manufacturers to use the OLED polymer material system.
OLED key element includes ITO conductive glass, small molecular organic materials, packaging materials, high purity metallic material, low temperature polycrystalline silicon TFT technology and drive IC.In order to material needs, TFT-LCD requires a glass substrate, backlight plate, polarizing plate, color filter and liquid crystal materials, a total of the combined panel thickness about 1 centimeters, but the OLED material includes only 1 piece about 1.3mm glass substrate as well as less than 0.3mm high purity metal materials and ITO conductive glass, the total thickness of less than 2mm, phase comparison, the OLED panel thickness of only about TFT LCD 10~20% OLED TFT LCD, thus not only reducing than many materials, thus reducing the production cost, moreover because the OLED and TFT LCD luminous source different, therefore also has a perspective on the concerns.
Currently in OLED two technology system, low molecular weight OLED for Japanese master, and polymer PLED technology and patented by British technology company CDT master, Taiwan Han Li photoelectric is the first introduction of the CDT technology cooperation company.OLED is used by the glass substrate thickness slightly greater than 1mm, plus the driver IC and glass protection layer thickness, only about 2mm, than the general LCD thickness decreases a lot, and driving voltage of PLED volts only 3-5, reaction time is almost instantly, consistent with the dynamic image display requirements, in addition, PLED does not need after a thin film process, the investment cost is low, the average cost of production after less than half of TFT LCD, but PLED commodity low process there are still technical bottleneck exists, namely PLED in product color is still difficult.Relative to PLED, low molecular weight OLED is easily colored, however because of high OLED driving voltage, energy use efficiency is poor, yield is low, but the process is stable and easy to control.Due to the low molecule OLED investment phase contrast PLED high, also makes the average cost is higher than PLED, the industry generally believe that OLED will be the future high price, high added products development, PLED is positioned in a large quantity, low price products.
The key components and materials, Ritek in Taiwan on conductive glass has been a breakthrough, GigaStorage and cooperation in materials research and development; small molecular organic materials, domestic current medicines and materials by Nobuo cooperative development; metallic materials are also made of materials R & D, in addition the current global has low temperature polycrystalline silicon TFT Technology much of the company, and the Taiwan Industrial Technology Research Institute is one of the Taiwan, in the development of OLED also provided a lot of help, so Taiwan's future in the OLED industry development is worth to pay close attention to.In Taiwan's current investment business schedule, Ritek is probably the fastest pace of the industry, Ritek completed in 99 organic EL panel laboratory technology research and development, and the establishment of a glass substrate size 400*400mm production line, is the world's first use of fully automated production line manufacturers, since April the first OLED production line will be put into mass production stage, and will begin in October set up second full color organic EL production line.
It is worth mentioning that, the current global no manufacturer specializes in production of organic EL using ITO conductive glass, including PIONEER, PHILIPS are self-sufficient for private use, Ritek successfully developed an organic EL with ITO conductive glass, to seize the organic EL leading position is significant, and that Ritek has one of the world's first fully automated production lines, this year Ritek has the opportunity to win the global first throne; ProDisc input to the OLED R & D also has 2 years, pilot line is expected at the end of 8, the beginning of next year production; GigaStorage also with ITRI cooperation into the OLED industry, estimated that next year will start of production OLED monochrome, 2 years after the production of colorful OLED; in addition to the League of nations photoelectric as the main investment established couplet photoelectric technology also has mastered to OLED complete process production technology, has set up a pilot plant, product quality is also quite satisfactory; Shenghua investment victory garden science and technology since the American manufacturers exclusive transfer OLED manufacturing technology, is expected next year second season can be put into mass production.
OLED is only the development of single color small size display, mainly used in vehicle type display, mobile phone game machine, PDA, Handled- PC, but the future is in high resolution color small size of display after the successful development, it can be used in camera, digital camera, SMARTPHONE etc..In addition, according to the Stanford Resources OLED estimates, in 2005 the output value will exceed $715000000, OLED growth is worth looking forward to future market.Conversely, because OLED's rapid rise, for small and medium size display application market, therefore, in the next few years, the small size TN/STN industry will be faced with major impact.
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