Fibre-like light-emitting diodes for wearable displays

South Korean researchers have developed fibre-like light-emitting diodes (LEDs) that can be used to create flexible wearable displays.
Traditional wearable displays are manufactured on a hard substrate, which is later attached to the surface of clothes. This technique has limited applications for wearable displays because they are inflexible and ignore the characteristics of fabric.
Professor Kyung-Cheol Choi and his research team from the School of Electrical Engineering at KAIST, South Korea, focused on fibres, a component of fabrics, and developed a fibre-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 three dimensional (3-D) rod (a polyethylene terephthalate fibre) from a solution, which functions like thread. 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 fibres with a 3-D cylindrical structure, which had been difficult in existing processes such as heat-coating process.
By controlling the withdrawal rate of the fibre, the coating's thickness can also be adjusted to the hundreds of thousandths of a nanometre.
The researchers said that this technology would accelerate the commercialisation of fibre-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.
The results of the work were published in the journal Advanced Electronic Materials.