Product Monday: Seoul Semi’s WICOP 3 Raises Many Questions

This article is based on publicly available information, as of 10/30/26.

Seoul Semiconductor’s WICOP 3 product release announcement, late last week, raises a fundamental question: how does it make white light without phosphor conversion of a blue LED chip? The company says affiliate Seoul Viosys has begun mass-producing rare-earth-free white microLEDs, reporting 0.015 lumens from a 25-by-10-micrometer chip at nearly 100 lm/W. It targets 200 lm/W within two years. But the release doesn’t supply a spectral power distribution (SPD), CRI figures, nor a spec sheet. For the lighting industry, the missing spectrum matters as much as the headline.

Rare-earth-free—or phosphor-free?

Those descriptions are not interchangeable. Rare-earth-free phosphors exist; eliminating rare earths does not, by itself, establish that a device has eliminated wavelength conversion. Seoul goes further, saying WICOP 3 generates white light “from gallium nitride (GaN) alone,” without plastics or silicone. Yet the release does not explain the emitting structure or explicitly document the absence of every conversion layer. Several of the diagrams provided “imply” there is no phosphor layer at all. Is light generated directly at multiple semiconductor wavelengths (such as RGB), or does another mechanism broaden the emission?

“GaN alone” also needs unpacking. Does that mean a GaN-based semiconductor system incorporating indium gallium nitride active regions, rather than literally only GaN? A material stack, cross-section and electroluminescence spectrum would clarify what the marketing shorthand leaves unresolved.

What makes it monolithic?

A package-free chip is not automatically proof of a monolithic white-emitting architecture. The release needs to distinguish one epitaxially grown, multicolor structure from bonded emitters, stacked junctions or other integration approaches. How many emitting regions and electrical contacts are involved? Can their outputs be controlled independently? The Seoul press release gives no indication of tunable output.

There is research precedent for direct monolithic white emission: KAUST researchers combined blue- and red-emitting InGaN quantum wells with V-shaped structures to obtain broadband light. That demonstrates one possible route in 2021, but it is not evidence that WICOP 3 uses it. Crucially, that device’s white point changed with current—another behavior Seoul should characterize.

Where does efficient red come from?

If WICOP 3 uses direct InGaN emission for red, its long-wavelength performance deserves particular scrutiny. Higher indium content makes red emission possible but brings crystal-quality, carrier-overlap and voltage challenges. White efficacy alone cannot establish that these problems have been solved.

What are the red component’s wavelength, linewidth, external quantum efficiency and wall-plug efficiency? Does its contribution survive realistic junction temperatures and dimming? Until Seoul publishes wavelength-resolved results, an efficient red emitter remains a question, not a demonstrated consequence of the announcement.

What would make it lighting-ready?

Seoul reports chromaticity within a CIE white region. That does not disclose spectral completeness. Buyers need SPD curves across current and temperature, CCT and Duv bins, CRI including R9, and TM-30 results—not simply a white coordinate and lumen figure.

The nearly 100-lm/W claim also needs operating current, junction temperature and measurement boundaries. Reliability claims need lumen-maintenance and chromaticity-shift evidence; cost claims need assembly-level accounting. How do microscopic emitters scale into useful lighting systems, with interconnects, thermal management and optics included? WICOP 3 may be significant. The next press release should replace technical ambiguity with clear and complete specifications.

All images provided by Seoul Semiconductor.

David Shiller

David Shiller is the Publisher of LightNOW, and Senior Business Development Consultant at Capacity Consulting, a North American consulting firm providing business development services to advanced lighting manufacturers. The ALA awarded David the Pillar of the Industry Award. David has been co-chair of the ALA’s Engineering Committee since 2010. David established MaxLite’s OEM component sales into a multi-million dollar division. He invented GU24 lamps while leading ENERGY STAR lighting programs for the US EPA. David has been published in leading lighting publications, including LD+A, enLIGHTenment Magazine, LEDs Magazine, and more.

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