Clothing usually is formed with textiles and has to be both wearable and washable for daily use; however, smart clothing has had a problem with its power sources and moisture permeability, which causes the devices to malfunction. To solve this problem, a textile-based, wearable display module technology was developed that is washable and does not require an external power source.

The wearable display modules integrate polymer solar cells (PSCs) with organic light-emitting diodes (OLEDs). PSCs have been one of the most promising candidates for a next-generation power source, especially for wearable and optoelectronic applications because they can provide stable power without an external power source, and OLEDs can be driven with milliwatts. They are both very vulnerable to external moisture and oxygen. An encapsulation barrier is essential for their reliability. The conventional encapsulation barrier is sufficient for normal environments; however, it loses its characteristics in aqueous environments such as water. It limits the commercialization of wearing displays that must operate even on rainy days or after washing.

The new technology employs a washable encapsulation barrier that can protect the device without losing its characteristics after washing through atomic layer deposition (ALD) and spin coating. With this encapsulation technology, textile-based wearing display modules — including PSCs, OLEDs, and the proposed encapsulation barrier — exhibited little change in characteristics after 20 washings with 10-minute cycles. Moreover, the encapsulated device operated stably with a low curvature radius of 3 mm and showed high reliability.

The new display module exhibited no deterioration in properties over 30 days, even after being subjected to both bending stress and washing. It uses a less stressful textile compared to conventional wearable electronic devices that use traditional plastic substrates.

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This article first appeared in the June, 2019 issue of Tech Briefs Magazine.

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