Mar 7, 2017: Wearable displays are becoming popular with more and more advancements. These displays have transformed from rigid to flexible, allowing more innovative designs to be explored.
In this scenario, OLEDs are emerging as a promising technology for wearable displays. OLEDs have many advantages to meed the requirements, like flexibility, thinness, light weight, and transparency.
While LEDs have been integrated into textiles, it is difficult to integrate OLEDs into textiles because of their extremely rough surfaces and wavy shapes.
However, A research team headed by Prof. Kyung Cheol Choi of the School of Electrical Engineering at the Korea Advanced Institute of Science and Technology (KAIST), in collaboration with KOLON Glotech, a Korean outdoor clothing company, used OLEDs to develop clothing-based light-emitting devices.
The team developed two devices—reliable fabric-based OLEDs and high-luminance fiber-based polymer light-emitting diodes (PLEDs).
The fabric-based OLEDs is made of flexible and transparent multilayer barrier films, and are designed for long-term reliability. It has operational lifetimes that exceeds 1,000 hours under the conditions of 30°C and 90% relative humidity.
The team demonstrated the OLEDs on rough fabrics through thermal lamination of thin planarization sheets. It also verified the stable operation of these devices with the help of cyclic bending tests.
The fiber-based PLEDs were developed with the help of a simple dip-coating method to coat polymer layers concentrically onto fibers. The researchers dip-coated a conducting polymer—PEDOT:PSS—several times, with the layers then functioning as planarization layers as well as electrodes. As a result, the device showed high luminance exceeding 1,000 cd/m2, a level sufficiently high for everyday applications.
Professor Choi said, “Our research will become a core technology in the development of LEDs on textiles, which are fundamental elements of fabrics. Hopefully, we can lower the barrier of wearable displays to enter the market.”
The team is hopeful that this technology will accelerate the commercialization of fiber-based wearable displays as it offers low-cost mass production using roll-to-roll processing, a type of technology applied to create electronic devices on a roll of flexible plastic or metal foil.