OSRAM Opto Semiconductors has set a new laboratory record of 142 lm/W
for the efficiency of a warm white LED light source. With a correlated
color temperature (CCT) of 2755 K the LED achieves a good color
rendering index (CRI) of 81. Measurements were taken under standard
conditions: room temperature and pulsed mode at an operating current
density of 350 mA/mm².
Bright warm white light with high efficiency is particularly important
for lighting applications in the residential sector. The laboratory
setup for a warm white LED shows the enormous potential of these
energy-saving semiconductor light sources: The peak value of 142 lm/W
measured under standard conditions is achieved at a color perception
that very closely matches that of a classic incandescent lamp (color
coordinates cx 0.46/ cy 0.41 on the Planckian curve).
“If we explore this technical approach further and allow
deviations from the Planckian curve we should even now be able to
achieve higher efficiency values of up to 160 lm/W for a correlated
color temperature of 3000 K (cx 0.45/ cy 0.44)”, said Dr. Norwin
von Malm, Predevelopment Manager at OSRAM Opto Semiconductors.
“If we apply this approach to a 2 mm² chip we can improve
efficiency by a further 10 to 15 percent for the same operating
current. We would then expect 180 lm/W for a pure warm white LED and
good color rendering.”
The increase in efficiency was made possible by combining new
procedures in thin-film and UX:3 chip technologies and in conversion.
Development engineers at OSRAM Opto Semiconductors have benefited here
from combined know-how in all aspects of the production process. These
include epitaxial growth, thin-film chip architectures, conversion
processes and package technologies.
For more information go to www.osram-os.com