CINNO Research Industry News, KAIST (Korea Advanced Institute of Science and Technology) said on April 20 that the research team of Professor Choi Kyung-chul of the Department of Electrical and Electronic Engineering has developed a technology to achieve white OLED on a line thinner than a hair. This technology is expected to be applied on electronic fiber displays.
A concept diagram of a white OLED electron fiber display developed by KAIST researchers
Based on the self-developed deep coating technology, Professor Cui Jingzhe's research team has been committed to the research of displaying essential element technologies such as fluorescent OLED or driveable high-efficiency phosphorescent RGB OLED with electronic fibers. However, the development of white OLED technology has encountered many difficulties, which is a necessary element of technology to achieve full-color display or lighting.
The three primary color OLED has a single multilayer structure, but the white OLED has a multi-layer structure of up to 2 to 3 times its size, which is difficult to achieve on the fiber. In addition, the charge generation layer (CGL) located in the middle of the multilayer structure is thinner than other organic layers and is a structure susceptible to fiber curvature. This is also why it is not suitable to achieve white OLED on fibers.
The research team noticed a deeply coated white single-light-emitting layer design suitable for the fiber structure. A white single luminescent layer consisting of a tri-primary luminescent material and multiple charge transporters balanced by charge is designed through a simulation and optimization process. In addition, the materials are designed to make the deep coating process possible. In order to withstand bending, pressure, water, etc., and operate stably, the protective layer is also coated.
White OLED film image stacked on fibers observed with white OLED electron fibers and microscope image (left) and injection electron microscopy (SEM) (right)
This results in a white OLED fiber that ensures outdoor recognition with a luminosity of up to 700cd/m2 and electro-optical properties of 10cd/A. The use of a structure that optimizes the energy transfer process allows it to appear white and emit a stable white light without being affected by the driving environment.
Researchers expect that white OLED fibers can be applied to various fields such as fashion, functional clothing, and vehicle design, including high-quality fiber displays.
This study was led by Dr. Rongxia Huang of Professor Choi Kyung-chol's research team as the first author. The research was supported by the Core Technology Development Project of the Ministry of Industry, Trade and Resources of Korea for the electronic components industry. The research results were recently published in the academic journal "Advanced Science" in the field of nanotechnology.
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