Lumileds tops white LED brightness contest
Breakthroughs in epitaxy, packaging, device physics and phosphors are behind a new record-breaking white LED chip developed by Philips Lumileds.
The San Jose, CA, company, which does not quote any peer-reviewed journal publication to support its claim, says that its 1 mm x 1 mm2 power chip produced 136 lumens when driven at 350 mA and 502 lumens at 2 A.
This equates to luminous efficacies of 115 lm/W at 350 mA and 61 lm/W at the higher drive current.
The high currents are significant "“ most recent claims of breakthroughs in LED efficacy have typically involved smaller, 20 mA-rated chips. However, the larger, so-called "power" chips are the ones that will be required for widespread penetration of important applications such as car headlamps and general lighting in the home.
Another key aspect of the Lumileds claim is the white color temperature of 4685 K. Relatively low for a high-efficacy LED chip, this figure indicates that the white color emitted is closer to the quality of light that is desirable inside the home.
In December, Korea s Seoul Semiconductor claimed to have developed a single-chip 100 lm/W white LED operating at 350 mA and delivering 240 lm (see related story).
The first commercial versions of Seoul s chips produce a relatively harsh white light rated at 6500 K, although the company indicated to compoundsemiconductor.net at the time that color temperatures as low as 2800 K were in development.
According to Lumileds, the first commercial products to incorporate the enhanced device designs will be released before the end of March 2007, with many others set to follow over the next 18 months.
Remarkably, the efficacy record quoted in Lumileds press release is 17 times greater than that of its first power LED, which was introduced in 1999.
Whether or not Lumileds, Cree, Seoul Semiconductor or Nichia is actually producing the brightest LEDs, it is clear that the technology required for widespread adoption of solid-state lighting is progressing at a very rapid pace in all corners of the world.
