Fiber OLEDs Developed For Wearable Displays

Researchers have fabricated highly efficient OLEDs on an ultrathin fiber for use in wearable displays. The weavable OLEDs, which are formed from a simple, low-temperature solution process, demonstrated performance values comparable to OLEDs fabricated on planar substrates. The values obtained for the fiber OLEDs in the areas of efficiency and lifetime indicate that these solution-processed OLEDs could be applied to cylindrical shaped fibers for use in electronic textiles, without a reduction in performance.

Researchers from Korea Advanced Institute of Science and Technology (KAIST) used a dip-coating method on a 3D fiber to design an OLED structure compatible with fiber.

Fiber-based OLEDs woven into knitted clothes. Courtesy of KAIST.

The team demonstrated that the fiber OLEDs could withstand tensile strain up to 4.3 percent at a radius of 3.5 mm while retaining more than 90 percent of their efficiency. The fiber OLEDs exhibited luminance and current efficiency values of over 10,000 cd/m² and 11 cd/A.

Through hand-weaving, researchers verified that the fiber OLEDs could be woven into textiles and knitted clothing. To demonstrate the scalability of their proposed scheme, the KAIST researchers tested the approach on fibers in a range of diameters, including 300, 220, 120 and 90 μm, which is thinner than a human hair.

Researchers noted that although the experiments were carried out at a low temperature, fibers vulnerable to high temperatures could also employ this fabrication scheme. They also said that the approach would be suitable for cost-effective reel-to-reel production.

“Existing fiber-based wearable displays had limitations for applicability due to their low performance," professor Kyung Cheol Choi said. "However, this technology can fabricate OLEDs with high performance on fibers. This simple, low-cost process opens a way to commercialize fiber-based wearable displays.”

The research was published in Nano Letters (doi: 10.1021/acs.nanolett.7b04204).