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Scientists Develop Flexible Organic LED for a Candlelight Effect

Candles create a warm light ideal for an unforgettable dinner or a relaxing evening at home. However, other illumination options, such as electric candles, emit harmful blue wavelengths that disrupt the circadian cycle.

Scientists Develop Flexible Organic LED for a Candlelight Effect.
A bendable organic LED with a natural mica backing releases a strong, candlelight-like glow. Image Credit: Andy Chen and Ambrose Chen.

Researchers have now developed a better bending organic LED that emits candlelight-like light for flexible lighting and smart displays that individuals can use at night, according to ACS Applied Electronic Materials.

Jwo-Huei Jou and colleagues previously developed organic LEDs that provided warm-white light akin to candles. The devices did, however, produce considerable blue wavelength light, which can disrupt sleep by suppressing the generation of melatonin in the human body. These gadgets were rigid and built of solid materials.

Using a plastic backing, like with other organic LEDs, is one approach for making them flexible. Plastics, on the other hand, do not hold up well to repetitive bending. Mica, a natural mineral with great temperature tolerance that can be broken into flexible, transparent sheets, is another alternative for the backing.

As a result, Jou, Ying-Hao Chu, and colleagues aimed to create a flexible candle-like light with a long lifespan by developing an even better organic LED and applying it to a mica substrate.

The researchers created the LED’s anode by depositing a clear indium tin oxide coating over a transparent mica sheet that could bend 50,000 times without breaking. The scientists then created a light-emitting layer by combining the luminescent material N,N’-dicarbazole-1,1’-biphenyl with red and yellow phosphorescent pigments.

This layer was then sandwiched between two electrically conductive solutions, one with the anode on one side and the other with an aluminum layer, resulting in a flexible organic LED.

The apparatus created a brilliant, warm light with fewer blue wavelength emissions than natural candlelight when a continuous current was applied to it. According to calculations, 1.5 hours of exposure to the LED suppressed melatonin synthesis by 1.6%, while light from a cold-white compact fluorescent lamp suppressed melatonin production by 29%.

The versatility of their candlelight-like organic LED, according to the researchers, provides fresh design possibilities for blue-light-free nighttime electronics.

The Ministry of Science and Technology in Taiwan, Republic of China provided funding to the writers.

Journal Reference:

Chen. T, et al. (2022) Flexible Candlelight Organic LED on Mica. ACS Applied Electronic Materials doi:10.1021/acsaelm.2c00123.

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