Reducing Blue Light: A New Type of LED That Won’t Keep You Up All Night

This prototype device creates a warm white light without the blue hues that can cause health problems.
Credit: Jakoah Brgoch

To be more energy efficient, many people have replaced their incandescent lights with light-emitting diode (LED) bulbs. However, those currently on the market emit a lot of blue light, which has been linked to eye troubles and sleep disturbances. Now, researchers reporting in ACS Applied Materials & Interfaceshave developed a prototype LED that reduces — instead of masks — the blue component, while also making colors appear just as they do in natural sunlight.

LED light bulbs are popular because of their low energy consumption, long lifespan, and ability to turn on and off quickly. Inside the bulb, an LED chip converts electrical current into high-energy light, including invisible ultraviolet (UV), violet, or blue wavelengths. A cap that is placed on the chip contains multiple phosphors — solid luminescent compounds that convert high-energy light into lower-energy visible wavelengths. Each phosphor emits a different color, and these colors combine to produce a broad-spectrum white light.

Commercial LED bulbs use blue LEDs and yellow-emitting phosphors, which appear as a cold, bright white light similar to daylight. Continual exposure to these blue-tinted lights has been linked to cataract formation, and turning them on in the evening can disrupt the production of sleep-inducing hormones, such as melatonin, triggering insomnia and fatigue.

To create a warmer white LED bulb for nighttime use, previous researchers added red-emitting phosphors, but this only masked the blue hue without getting rid of it. So, Jakoah Brgoch and Shruti Hariyani wanted to develop a phosphor that, when used in a violet LED device, would result in a warm white light while avoiding the problematic wavelength range.

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