Seoul Semiconductor Develops Sunlight-Spectrum LED

A New Lighting Innovation Gaining Attention – Seoul Semiconductor

# Source: Reform Sangyo Shinbun, Issue No. 1658 (July 28, 2025)

Seoul Semiconductor has developed an innovative LED light source—SunLike—that reproduces a spectrum nearly identical to natural sunlight.
The technology is gaining attention for its positive effects on eye health, including reducing eye fatigue and potentially alleviating myopia.
It is already being adopted in residential lighting products in Japan and is also in use at museums, aquariums, and other specialized facilities.
A company executive shared insights into the development process and future plans.

[Figure 1] Spectrum Comparison: SunLike vs. Conventional LED
SunLike reproduces a full spectrum of light close to that of natural sunlight.

The Long-Awaited “Violet LED”

SunLike was originally developed to reproduce natural colors accurately, especially for artwork and exhibits.
Traditional LEDs generate white light by combining blue LEDs with yellow, green, and red phosphors.
However, the visible light spectrum consists of seven colors—red, orange, yellow, green, blue, indigo, and violet—and conventional blue LEDs lack violet wavelength components.

This absence creates noticeable discrepancies in color perception under artificial lighting versus natural sunlight. By incorporating violet excitation LEDs,
SunLike enables a more complete reproduction of the visible spectrum, achieving light that closely resembles natural daylight.

"It took us around 10 years to commercialize this product," said Vice President Yoshihide Kimura.
In fact, SunLike has already been adopted in settings requiring high color fidelity,
such as the Royal Palace Museum in Milan and for illuminating Pompeii murals. In Japan, museums, temples, and historic buildings are increasingly adopting SunLike for similar reasons.

During the development process, researchers hypothesized that this full-spectrum light source might have additional health benefits—leading to further clinical investigation.

Improved Eye Health and True-to-Life Color Rendering
Eye Fatigue Reduction and Myopia Improvement

According to a study by Seoul National University College of Medicine, SunLike reduced eye fatigue by 4.3 times compared to conventional blue LEDs, shortened the time to fall asleep by 23%, and improved sleep quality by 1.3 times.

A study by the Singapore Eye Research Institute also indicated that exposure to SunLike lighting slowed the progression of myopia in chicks—whose eyes structurally resemble human eyes.
Based on these findings, the Chinese government is now promoting SunLike-equipped desk lamps and classroom lighting in schools, as nearly half of children in China are affected by myopia.
Adoption is expanding in schools and educational institutions across Europe as well.

Additional research by Harvard Medical School in the U.S. found that exposure to SunLike lighting increased problem-solving accuracy by 5%, sped up processing times by 3.2 times, and reduced nighttime awakenings by 45%.
Daytime alertness also improved.

As a result, SunLike is being actively installed in study desks, classrooms, kindergartens, cram schools, and office lighting.
Thanks to its full-spectrum properties, it is also being introduced into hospitals, nursing homes, welfare centers,
and educational facilities in Europe and the U.S., where lighting can now be adjusted to better support human circadian rhythms.
Demand is rising in facilities with limited access to natural daylight.

“When people hear about lighting that mimics the sun, they may worry about UV exposure or sunburn.
But SunLike only reproduces the visible spectrum—it does not emit harmful ultraviolet or infrared rays,” said VP Kimura.
“Thanks to its high-fidelity color rendering, it also helps reduce customer dissatisfaction in environments like beauty salons, cosmetics stores, and fashion retailers where lighting can distort color perception.”

[Figure 2] Seoul National University Study: SunLike improved sleep quality by 1.3x and reduced time to fall asleep by 23%

Expanding Into High-End Residential Markets

Shinya Nakao, Head of Seoul Semiconductor’s Lighting Division, commented on the company’s future direction:
“We hope more lighting manufacturers will incorporate our LEDs into their products.
We’ve seen growing interest from luxury homebuilders and interior coordinators. In eldercare facilities, we’ve received feedback that meals appear more appetizing and food waste has decreased.
Lighting that contributes to health is becoming a key selling point and aligns with evolving market needs.”

As mass production expands, prices are expected to decrease, and expectations are high for wider adoption of this next-generation light source.

📎 Related Link
SunLike Technology Overview – The World's Closest LED toNatural Sunlight