Philips Lumileds Achieves 139 lm/W in a Neutral White LED
Philips Lumileds' LUXEON Rebel LED can now deliver 139 lm/W in a neutral white LED. The top bin LED, developed with a single InGaN die and phosphor conversion, shows high-performance characteristics up to 139 lm/W and 138 lumens at 350 mA, with a forward voltage of 2.83 V. The CCT of the device is 5385K and the CRI is 70.
The performance gain partially results from improvements in chip level electrical injection efficiency and optical extraction efficiency, developed with funding from DOE. In that project, Philips demonstrated a 2x2 mm2 LED with a light output of 811 lumens, an efficacy of 99 lm/W, a CCT of 3307K, and a CRI of 75. The prototype was driven at a current density of 0.7 Amp/mm2, twice that of most high-brightness LEDs, which typically operate at 0.35 Amp/mm2 because of "droop"—when LEDs exhibit a significant drop in efficiency at higher currents. Philips engineers were able to drive the LED at a higher current density, thereby increasing the light output.
The output of 811 lumens achieved by the DOE-funded Philips project is nearly the output of a 60W incandescent bulb and enough for many lighting applications, thereby eliminating the need for multiple devices in a luminaire and considerably reducing the cost per kilolumen. In addition, it should make the luminaire more reliable by reducing the number of components, and smaller, more efficient light sources with higher light outputs would give luminaire manufacturers more flexibility when designing lighting products.