Dip coating could help make wearable polymer LEDs much cheaper to manufacture, scientists say.

AsianScientist (Aug. 19, 2015) - Researchers from the School of Electrical Engineering at Korea Advanced Institute of Research and Technology (KAIST) have developed fiber-like light-emitting diodes (LED) that can be use in wearable displays. The research findings were published in Advanced Electronic Materials.
Traditional wearable displays are manufactured hard substrates that are subsequently attached to the surface of clothes. This technique had limited applications for wearable displays because they were inflexible.
To solve this problem, the research team discarded the notion of creating light-emitting diode displays on a plane. Instead, they focused on fibers, a component of fabrics, and developed a fiber-like LED that shared the characteristics of both fabrics and displays.
The essence of this technology, the dip-coating process, is to immerse and extract a 3D rod (a polyethylene terephthalate fiber) from a solution. This fiber rod functions as fibers of the fabric. Then, the regular levels of organic materials are formed as layers on the thread.
The dip-coating process allows the layers of organic materials to be easily created on the fibers with a 3D cylindrical structure, which had been difficult in existing processes such as heat-coating process. By controlling of the withdrawal rate of the fiber, the coating's thickness can also be adjusted to the hundreds of thousandths of a nanometer.
An overview of the dip coating process. Credit: KAIST.
The researchers said that this technology would accelerate the commercialization of fiber-based wearable displays because it offers low-cost mass production using roll-to-roll processing, a technology applied to create electronic devices on a roll of flexible plastics or metal foils.
Professor Choi Kyung Cheol, the corresponding author, said, “Our research will become a core technology in developing light emitting diodes on fibers, which are fundamental elements of fabrics. We hope we can lower the barrier of wearable displays entering the market.”
Lead author of the paper, Kwon Seon-Il, added, “This technology will eventually allow the production of wearable displays to be as easy as making clothes.”
The article can be found at: Kwon et al. (2015) High Luminance Fiber-Based Polymer Light-Emitting Devices by a Dip-Coating Method. Read more from Asian Scientist Magazine at: http://www.asianscientist.com/2015/08/in-the-lab/kaist-fiber-led-light/