15 March 2011

Osram hits record 142lm/W efficiency for 2755K warm-white LED

Osram Opto Semiconductors GmbH of Regensburg, Germany has set a new laboratory record of 142lm/W for the luminous efficiency of a warm-white LED light source. With a correlated color temperature (CCT) of 2755K 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 350mA/mm2.

Picture: Lab setup for a warm-white LED achieves a peak value of 142lm/W directly on the Planckian curve at 2700K; an optimized setup at 3000K could achieve 160lm/W.

Bright warm-white light with high efficiency is particularly important for lighting applications in the residential sector. Osram Opto says that the lab setup for a warm-white LED shows the enormous potential of energy-saving semiconductor light sources: the peak value of 142lm/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 160lm/W for a correlated color temperature of 3000K (cx 0.45/ cy 0.44),” says Dr Norwin von Malm, pre-development manager at Osram Opto. “If we apply this approach to a 2mm2 chip, we can improve efficiency by a further 10–15% for the same operating current,” he adds. “We would then expect 180lm/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. Osram Opto says that its development engineers have benefited from combined know-how in all aspects of the production process, including epitaxial growth, thin-film chip architectures, conversion processes and package technologies.

Tags: Osram Warm-white LEDs

Visit: www.osram-os.com

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