Houston University scientists have developed a new LED prototype that reduces – instead of masking – the blue component.
According to lead scientists Jakoah Brgoch and Shruti Hariyani, LED light bulbs are known for their low energy consumption, long lifespan and ability to turn on and off quickly. This is why many people have replaced their incandescent lights with light-emitting diode (LED) bulbs.
However, LEDs currently on the market emit a lot of blue light and these have been linked to eye troubles and sleep disturbances.
Each LED bulb consists of a chip that converts electrical current into high-energy light, including invisible ultraviolet (UV), violet or blue wavelengths.
The chip comes with a cap containing 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.
Scientists have been adding red-emitting phosphors to create a warmer white LED bulb for nighttime use. But this only masks the blue hue without getting rid of it.
In order to remedy this, Brgoch and Hariyani have successfully identified and synthesized a new luminescent crystalline phosphor containing europium ((Na1.92Eu0.04)MgPO4F).
In thermal stability tests conducted so far, the phosphor’s emission color was consistent between room temperature and the higher operating temperature (301 F) of commercial LED-based lighting.
Moreover, in long-term moisture experiments, the compound showed no change in the color or intensity of light produced.
To see how the material might work in a light bulb, Brgoch and Hariyani fabricated a prototype device with a violet-light LED covered by a silicone cap containing their luminescent blue compound blended with red-emitting and green-emitting phosphors.
As envisioned, it produced the desired bright warm white light while minimizing the intensity across blue wavelengths, unlike commercial LED light bulbs.
It also revealed the color of objects almost as well as natural sunlight, fulfilling the needs of indoor lighting.
Image and content: American Chemical Society