On November 16, a paper titled “Reliable Actual Fabric-Based Organic Light-Emitting Diodes: Toward a Wearable Display” was published in Advanced Electronic Materials. Written by researchers under the supervision of Professor Kyung Cheol Choi from the Advanced Display and Nano Convergence Laboratory, the paper describes demonstrations of fully operational, commercial-scale, fabric- based organic light-emitting diodes (OLEDs).
Wearable devices, as the paper describes, “are attracting considerable attention because they offer the potential combination of real-time personal communication and convenient portability”. Indeed, wearable devices continue to rise in popularity today (see 2016 Wearable Computer Contest, p. 4), and along with batteries, displays have been consistently pointed out to be the most challenging component of commercial-scale wearable computers in terms of stability and lifetime. Following an acknowledgement of the limitations of wearable technology embedded in peripherals/accessories, such as watches, glasses, and necklaces, the authors assert that fabrics are the “ideal platform for wearable devices”, simply because everyone wears clothes.
As such, the research team obtained 100-μm thick polyester-fiber-based woven fabric substrates from fabrics manufacturer Kolon Glotech and built on the substrates a series of intricately stacked layers, which together rendered the final product as flexible as everyday fabric yet more robust to oxygen and moisture than any other existing display available today.
The key layers of the new technology are the polyurethane (PU) film and the aluminum oxide (Al2O3) and polyvinyl alcohol (PVA) films. As seen in the figure, the PU film is located at the very bottom of the stack. To this film belong two layers: the bottom of which has a low viscosity in order to smoothen the stiffness of the woven fabric underneath, and the top of which has a higher viscosity so that the rest of the stack could safely be built on a flat surface. Then come the two multilayer barriers; one is right above the PU film while the other is at the very top of the stack. These Al2O3/PVA multilayer barriers act to encapsulate and protect the sensitive electronics from oxygen and moisture.