Increasing demand for luminous efficacy, a high color rendering index, and cost-effectiveness is fueling the lighting industry. NanoMarkets believes that LED phosphors, will therefore enjoy an expanding market.
Phosphors are the critical luminescent materials for LEDs. In a white LED, for example, the phosphor emits up to 95 percent of the visible lumens. Existing phosphors have been able to provide LEDs with 100 percent greater increase in LED efficacy and a 50 to 200 percent decline in price. The use of phosphors has also helped drive down the price of high-quality LEDs by a dramatic amount.
As a result, NanoMarkets believes that LED phosphors will continue to play a major role in the development of the LED phosphor market. In particular, we think that the use of phosphors in applications such as traffic lights and exit signs will become key drivers for the phosphor market.
More generally, we expect in LED applications where a lower cost per lumen, a high CRI, and a lower cost of ownership can be demonstrated, phosphor penetration will continue to grow. We also think that phosphor choice may help reduce consumer perception of LED lamps as being cold, dull, and above all, unaffordable.
Also another critical factor is who owns the IP in the phosphor space; a factor that has shaped—and clearly will continue to shape—the market. Other factors that seem likely to continue and which NanoMarkets will also determine the structure of the phosphor sector are the “division of labor” based on both supplier size and geography.
What we have in mind here is that our analysis indicates that large phosphor players will continue to improve their products through the deployment of efficient production lines while smaller players will seek novel phosphor solutions. There is also something of a divide between Asian and European/U.S. firms with regard to product development.
Emerging Requirements for LED Phosphors
For now the standard, blue chip Ce:YAG combination is the most popular on the market, green and red phosphors are steadily growing their market share, particularly for applications that require a high CRI and good color reproducibility, such as general lighting and liquid crystal display (LCD) backlights in cell phones and flat-panel displays.
What NanoMarkets is seeing though is intensified competition for new green/red phosphors. What this means in practical terms is that certain companies—like Intematix (U.S.) and Mitsubishi Chemical Group Science—are actively working in this area and strengthening their IP. Where we believe the thrust of the important R&D work in phosphors needs to be in the next few years is in the areas discussed below.
Color-mixed solutions: In NanoMarkets' opinion, there is considerable room in the market for color-mixed solutions. The workhorse for current lighting products is phosphor-converted blue light, and there is still potential for energy improvement and cost reduction in that technology.
Color rendering indices: For high-quality LED solutions, the key factor is to increase the CRI at various color temperatures while maintaining high efficiency.
NanoMarkets believes that new phosphors that have broad emission spectra (except for the red phosphors, where a small bandwidth is needed to avoid NIR-losses), or emit at various wavelengths with minimized re-absorption are needed.
Color consistency over time must also be guaranteed. Color conversion requires temperature-stable phosphor solutions, while RGB (red, green, blue) solutions require color controls that compensate for the divergent aging properties of LEDs of different colors.
To take advantage of these opportunities, we believe that an understanding of the color mixing mechanism at the molecular level is needed to be able to maintain the same color impression during the lifetime of a single lamp and between individual lamps. This goal is difficult to achieve, however, because the temperature and aging behavior of red, amber, and blue LEDs is different.