Yole Développement report delves into the IP surrounding white-light LED phosphors

Lyon, France--A market and technology patent investigation by Yole Développement, called "LED Phosphors and Downconverters," describes the current situation relating to the intellectual property (IP), including patents, surrounding the technology behind the phosphors used in white-light LEDs. Most of the major LED players are present on the list of the top patent assignees—but independent phosphor manufacturers are also emerging as major forces in the IP landscape.

LED phosphor IP is shaping the industry

The first commercial gallium nitride (GaN)-based blue LEDs were produced in Japan in the mid 1990s after researchers Shuji Nakamura at Nichia and Professor Akasaki at Nagoya University (with the IP assigned to Toyoda Gosei) removed some of the major roadblocks associated with this technology, such as p-doping and epitaxy quality. Next, some fundamental patents describing the combination of a blue LED and a phosphor to produce white LEDs were filed by Nichia, Osram, ATMI, and others. From then on, use of white-light LEDs boomed.

The IP around LED phosphors is a major force in the LED industry. With more than 40 litigation cases, it is also used as leverage by companies that have negotiated close to 70 licensing and supply agreements to date. It can also be argued that in the first half of the 2000s (the "aughts"), the strict enforcement and lack of license grants for some fundamental IP related to the design and manufacturing of white LEDs may have slowed down the progress of the industry by preventing more efficient competition that would allow prices to decrease. The Yole Développement report identifies the key players with the most relevant IP and provides an overview of the phosphor-related IP litigation and licensing that has shaped the industry since the mid 1990s.

More than 4500 relevant patent families have been identified, says Eric Virey, senior analyst LED at Yole Développement; they have been segmented by type (composition patent or phosphor configuration patents) and organized in various technology groups: garnets, silicates, nitrides and oxynitrides, and quantum dots. The report also includes a special focus on the emerging LED phosphor IP in China.

Composition focus shifting from yellow to red and green phosphors

With high performing silicates now widely available as a YAG substitute for yellow emission (blue LED light plus yellow phosphor light often makes for merely adequate white-light quality), the focus on new composition development and patent protection has mostly shifted toward red and green converters (which can lead to very high white-light quality and ultrahigh efficiency).

The market for those new phosphors and some of the most critical IP are currently dominated by Mitsubishi and Denka, which have acquired nitride and oxynitride licenses from NIMS. However, many other players are also developing nitride and oxynitride compositions, including Intematix, Beijing Yuji, and Lightscape (now Dow electronic materials). New material families are also considered as promising phosphors, including tungstate and molybdates, as well as Fluorides championed by GE.

Following recent progress in thermal stability and manufacturability, quantum dots (QDs) are also finally emerging as a credible option. Because of their narrow emission bands, use in LCD displays is the most promising application for the technology. In lighting, the use of red QDs in combination with standard phosphor could emerge in remote phosphor applications (meaning the phosphor is not coated right on top of the LED).

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