News Article
Osram raises the efficiency bar for warm white LED
The peak value of 142 lm/W measured under standard conditions is achieved at a colour perception that very closely matches that of a classic incandescent lamp.
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 colour temperature (CCT) of 2755 K the LED achieves a good colour 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 colour perception that very closely matches that of a classic incandescent lamp (colour 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 colour temperature of 3000 K (cx 0.45/ cy 0.44)”, said 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 colour 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.
