Green light material emits blue light to extend OLED lifetime

White light is the brightest star of lighting technology. The US Department of Energy (DOE) predicts that by 2020, the cost, efficiency, and life expectancy of OLED lighting will be inextricably linked to LEDs.

However, the industry currently suffers from the short life of organic light-emitting blue phosphor materials. The OLED light-emitting layer is mainly composed of red fluorescent material, green light material, and blue-light phosphor material. When the lifetime of one of the materials is attenuated, the whole OLED will fail. How to overcome the difference in material life and become an industrial challenge problem.
Taigong Research Institute developed “OLED Surface Plasmon Coupling Gain Technology” to convert the emission spectrum of green light materials into blue light, breaking the bottleneck of short organic blue light-emitting materials. (All images source: ITRI)

Taiwan Institute of Technology "blue light" solution, that is, do not use any blue light material, but the technology to make green light material as a blue light source, thereby developing the OLED surface plasma coupling gain technology PCOLED (Plasmon-Coupled Organic LED).

When the ITRI was conducting a light-emitting structure experiment of a green light material, it discovered that the green light material actually sent out an impossible blue light, which enabled the ITRI to start a new research direction. Later, it used physical thinking to design the green light material. Special structure, constantly adjusting parameters, finally find out and summarize the reasons and methods of green light blue light.

Finally, using the DML structure to produce a planar plasma-coupled effect, the luminescent spectrum of the green light material can be converted to blue light. The white light OLED can use the green light material to replace the traditional blue light material layer, and the lifetime is too short. To be solved, even more than 20 times longer than the traditional OLED.

In terms of efficiency, through continuous R&D and component optimization, DML's blue light-emitting efficiency has exceeded the level of existing blue-light fluorescent materials and most of the known blue phosphorescent materials, reaching 35cd/A. The OLED DML white light technology has been proven to emit white light with color rendering (CRI) of 77 and color temperature of 2039 K, and can be used for indoor lighting. ITRI has successfully turned on a large white light module of 10 cm x 10 cm.

At present, the ITRI team has applied for patents on related technologies in Taiwan, Germany, the United States, and China, and has also cooperated with private companies to further master OLED key materials and process technology and move toward industrialization.