INDUSTRY LEDs
While GAL phosphor’s broad green emission enables high CRI, our red phosphors hold the key to producing higher values of R9, which is a measure of how well an illumination source can capture deep, saturated shades of red. These phosphors, which are used in white LEDs serving retail and hospitality markets, are setting a new benchmark for colour stability: one that is imperceptible to the human eye, and measured at just 2SDCM (that is, a 2-step MacAdam ellipse, which is a well-known metric for measuring shifts in colour) in aggressive accelerated lifetime tests. In addition, these phosphors are relatively new, so different wavelengths and methods to improve the effi ciency of each composition are continually being discovered (see Figure 5).
Figure 5: Intematix has steadily increased the brightness of its red nitride materials. A bright future
Shipments of phosphors will rise as the LED-based lighting market grows. McKinsey & Company have reported that the LED-based lighting market should increase in value at an average of 38 percent per year between 2012 and 2016, and we anticipate that phosphor sales should increase even faster, as LED makers must use more red and green phosphor in the production of higher quality white-light sources with lower CCTs and higher CRI characteristics. Demand for more advanced phosphor materials is also rising as LED makers adopt more complex mixing strategies to compete on optimised brightness, CRI and R9 values.
Another reason we are very positive about the future is that, increasingly, our phosphor portfolio not only has materials with stable chemical structures that will last upwards of 50,000 hours − that is at least the lifetime of the bulb − but it also contains materials with excellent thermal stability.
Bulb makers want to drive their LEDs very hard, because this reduces the total chip count and thus the bill of materials, and this requires phosphors that are more chemically and thermally stable at high temperatures. Our newest phosphors perform particularly well in this regime.
For example, a chip packaged with GAL can maintain 97-98 percent of its initial brightness at 150 °C, and our red nitride survives the most rigorous lifetime tests with virtually no loss of brightness and perfectly stable colour. Bulb makers are
also moving away from phosphor-coated LEDs to a remote-phosphor architecture. Because phosphor particles are small, the light they create is naturally diffuse – so in a phosphor-coated LED, as light is created, a portion is emitted back toward the chip surface and is lost. This loss is avoided with remote phosphor, which also has the benefi t of operating at a lower temperature, further increasing the overall effi ciency.
To support the growth of solid-state lighting based on remote phosphors, we have developed materials specifi cally for this application, which can be applied to either a two-dimensional sheet or a three-dimensional shape, such as dome or a tube. Thanks to superior geometries, effi cacy is typically 15 percent higher.
However, a 30 percent hike in effi ciency is possible compared to a white LED with a diffuser.
By delivering this improvement, while ensuring excellent colour quality and stability with our robust, highly effi cient phosphors, we are helping to drive a revolution in solid-state lighting.
This revolution is not just about trimming our carbon dioxide footprint by using highly effi cient LEDs, more and more it is about illuminating homes and offi ces with a superior white light, making them better, more productive places to be.
© 2014 Angel Business Communications. Permission required.
Phosphors and China In mainland China, the vast majority of LED packaging fi rms are hampered by a lack of LED device IP associated with using the combination of blue chips and YAG or silicate phosphor. As a result, most Chinese companies face restrictions that impair their exports of Chinese products.
Intematix is helping to address the diffi culties faced by these Chinese companies, by delivering superior product performance, leveraging our local China manufacturing base, and offering an IP portfolio that covers both red and green phosphor compositions and their application in LEDs. Intematix phosphors are particularly valuable for Chinese LED makers who want to complete with higher light quality and must offer IP protected products to drive product exports to luminaire manufacturers selling to end customers such as Home Depot and Ikea.
June 2014
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