The new flexible OLED shines like a comfortable candlelight

Bendable OLEDs with natural mica lining give off a strong glow like a candlelight. Credits: Andy Chen and Ambrose Chen

The soft and soothing glow of candles creates the atmosphere of a special dinner or a quiet evening at home. However, some alternative lighting, such as electronic candles, emit light of unwanted blue wavelengths that interfere. Circadian rhythm of the body..Researchers reporting in the journal now ACS Applied Electronic Materials We have created an improved and flexible OLED that provides a candlelight-like glowing and bendable lighting and a smart display that people can comfortably use at night.

Earlier, Jwo-Huei Jou and other researchers developed organic LEDs that emit warm white light similar to that produced by candles. However, the device still emitted some blue wavelengths. This reduces the body’s production of melatonin and can interfere with sleep.

These devices were made of rigid material and could not be bent. One option to make them flexible is to use a plastic lining, as is done with other OLEDs. However, plastic does not withstand repeated bending well. Another option for backing is mica. It is a natural mineral with extreme temperature resistance that can be split into transparent sheets that can be bent. So Jou, Ying-Hao Chu and colleagues wanted to develop a better OLED and apply it to the mica lining to create a long-life bendable candle-like light.

Researchers have deposited a transparent indium tin oxide film on a transparent mica sheet as the anode of the LED. It was able to bend 50,000 times without breaking.Then the team mixed the luminescent material N, N’-Dicarbazole-1,1′-Uses biphenyl and red and yellow fluorescent dyes to produce a light emitting layer. This layer was then placed between the conductive solutions, with the anode on one side and the aluminum layer on the other side to create a flexible OLED.

A constant current through the device produced a bright, warm light with even less blue wavelength emission than a natural candlelight. Calculations show that exposure to LEDs for 1.5 hours suppresses human melatonin production by about 1.6%, while light from cold-white compact fluorescent lamps suppresses melatonin production by 29%. Researchers say the flexibility of OLEDs, such as candlelights, opens up opportunities for designing nighttime devices without blue light.

Reference: “Flexible Candle Light Organic LED on Mica”, Tun-Hao Chen, Hao-Jen Chen, Ching-Yu Weng, Feng-Rong Chen, De-Shiang Liou, Sun-Zen Chen, Ying-Hao Chu, Jwo- Huei Jou, May 9, 2022, ACS Applied Electronic Materials..
DOI: 10.1021 / acsaelm.2c00123

The author acknowledges funding from the Ministry of Science and Technology (Taiwan, Republic of China). The new flexible OLED shines like a comfortable candlelight

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