High‐Performance and Reliable White Organic Light‐Emitting Fibers for Truly Wearable Textile Displays

Light‐emitting fibers have been intensively developed for the realization of textile displays and various lighting applications, as promising free‐form electronics with outstanding interconnectivity. These advances in the fiber displays have been made possible by the successful implementation of the core technologies of conventional displays, including high optoelectronic performance and essential elements, in the fiber form‐factor. However, although white organic light‐emitting diodes (WOLEDs), as a fundamental core technology of displays, are essential for realizing full‐color displays and solid‐state lighting, fiber‐based WOLEDs are still challenging due to structural issues and the lack of approaches to implementing WOLEDs on fiber. Herein, the first fiber WOLED is reported, exhibiting high optoelectronic performance and a reliable color index, comparable to those of conventional planar WOLEDs. As key features, it is found that WOLEDs can be successfully introduced on a cylindrical fiber using a dip‐coatable single white‐emission layer based on simulation and optimization of the white spectra. Furthermore, to ensure durability from usage, the fiber WOLED is encapsulated by an Al2O3/elastomer bilayer, showing stable operation under repetitive bending and pressure, and in water. This pioneering work is believed to provide building blocks for realizing complete textile display technologies by complementing the lack of the core technology. Although the core technologies of organic light‐emitting devices (OLEDs) have been implemented in the form of fiber, the fiber WOLED, a core technology to realize full‐color displays and various applications, is still undeveloped. A fiber WOLED not only was reported for the first time but also exhibited a high level of optoelectronic performance, reliable color index, deformability, and durability.