kuraray


News Releases 2005

Invention of Ultra-Bright, Inorganic EL Light-Emitting Materials, and Joint Development of Next-Generation Light Source

October 12, 2005
T. CHATANI & CO., LTD.
Kuraray Co., Ltd.

T. CHATANI & CO. LTD. (Headquarters: Chuo-ku, Osaka; President: Yasuhiro Chatani; hereafter "CHATANI & CO.") and Kuraray Co., Ltd. (Headquarters: Chiyoda-ku, Tokyo; President: Yasuaki Wakui; hereafter "Kuraray") have announced their commencement of joint development of ultra-bright, inorganic electroluminescence (EL) blue and white light-emitting materials. CHATANI & CO. was the first in the world to invent such materials, and joint development is being undertaken to accelerate development of the materials.

The inorganic EL light-emitting materials invented by CHATANI & CO. far exceeds the properties of conventional EL materials in terms of the degree of brightness and longevity. This ultra-bright, long-lasting blue inorganic EL can be utilized as a surface illuminant by the coating method, opening the door to possible use in displays, including wall-mountable televisions with ultra-thin, large screens. Other foreseen uses include lighting applications that currently use mercury, which raises environmental issues.

The two companies will conduct joint development of a white light source product for LCD backlighting devices, indispensable for flat-screen televisions, with the aim of commencing sample shipments from autumn 2006. The future prospect of developing light-emitting materials for a variety of illuminants and full-color displays has also come into view.

The ultra-bright, inorganic EL material will be showcased at FPD International 2005, to be held from October 19-21, 2005 at the Pacifico Yokohama Convention Center (Yokohama, Japan).

EL materials, which light up when contacted with electricity, boast features that include self-luminescence and brightness, energy savings, rapid responsiveness and environmental friendliness. Such features are drawing attention to the efficacy of EL materials as a next-generation display material succeeding LCDs, PDPs, and also as a possible alternative to fluorescent tubes in lighting applications. Some mobile phones have begun to use EL materials as well. Wide-scale use of displays with EL materials is expected to begin from approximately 2008, and a number of companies are engaged in a development battle on a worldwide scale.

EL materials are either inorganic or organic. Though developed before organic EL materials, inorganic EL materials had required a high voltage (100-200V) alternator, and suitable blue-color materials with high brightness and longevity had not been discovered. Due to these factors, organic EL materials, which enable the design of various chemical compounds, have been the focus of development in recent years.

However, organic EL materials made from organic compounds can easily be oxidized or degraded with exposure to air, and can easily deteriorate due to humidity. In addition, when a driving current is added to increase brightness, the life of the material is shortened, making the greatest obstacle to development the trade-off between brightness and life cycle. Because of these downside factors, recent small-screen applications for products such as mobile phone displays have begun, but uses have not yet been extended to mid- and large-screen display products. The development of high-brightness, long-lasting blue light-emitting material necessary for whitening and for full coloring has been particularly slow in the case of organic EL.

With respect to light-emitting diodes (LED), a technology similar to EL, Nichia Corporation has developed a blue color material with brightness and longevity that make practical applications possible, including traffic signals and electronic bulletin boards. Although the scope of applications is broadening, the fact that LED is a point source means that applications are ultimately limited, and there are obstacles to its use in large flat panel displays. EL differs in that it is a surface illuminant.

Against this backdrop, the issue surrounding the widespread use of EL materials as an alternative to LC and PDP and other displays has been whether or not a high-brightness, long-lasting blue light-emitting material could be developed. After grappling with these and related issues for several years, CHATANI & CO. engineers have successfully become the first in the world to invent blue and white EL materials that are ultra-bright and long lasting, heretofore the most troubling technological hurdle. With application of a low-voltage (3-10V) direct current, both a high level of brightness (600,000cd/m², 5.5V) and longevity (see following chart) have been achieved.

Comparison of properties of ultra-bright, blue inorganic EL materials and conventional products-1
  Brightness (cd/m²) Longevity (hours)
Ultra-bright, blue inorganic EL material 350,000 25,000+ hours with no change in brightness
Conventional blue inorganic EL material 100 30,000 hours (hours with a 50% reduction in brightness)
Conventional blue organic EL material 1,000 10,000 hours (hours with a 50% reduction in brightness)
Comparison of properties of ultra-bright inorganic EL materials and conventional products-2
  Illumination area Brightness Efficiency Longevity Environment
Ultra-bright, blue inorganic EL material Surface *** ** *** **
Bulbs Point * * * ***
Fluorescent tubes Surface ** *** ** *
LED Point *** ** ** - *** **
Inorganic EL Surface * ** ** **
Organic EL Surface ** ** * **

*** : excellent, ** : average, * : poor

T. CHATANI & CO., LTD.

President Yasuhiro Chatani
Headquarters 8-15 Azuchimachi 1-chome, Chuo-ku, Osaka;
Capital ¥310 million (as of March 31, 2005)
Business Export and import and domestic trade of the following goods: automobiles, tires, industrial machinery & equipment, machinery for materials handling & transport, electrical / electronic equipment, tools / steel products, wood products, building materials, household consumer goods, and food products. Manufacture and sales of synthetic products comprising fibers and textiles, resins, and other chemical products

Kuraray Co., Ltd.

President Yasuaki Wakui
Headquarters 1-3 Otemachi 1-Chome, Chiyoda-ku, Tokyo;
Capital ¥89 billion (as of March 31, 2005)
Business Manufacture and sales of synthetic products comprising fibers and textiles, resins, and other chemical products