Osram Increases LED Efficiency

Developers at Osram Opto Semiconductors have succeeded in increasing the efficiency of red thin-film LEDs by 30 percent — a record. The latest generation of thin-film chips benefits from an optimized chip platform that has potential for further improvements. This boost in efficiency is opening up new LED applications in general illumination, in projection and in the industrial sector.

The record efficiency for an LED of 119 lm/W at an operating current of 350 mA (136 lm/W at 70 mA) has been achieved by the latest generation of a red 1-mm² thin-film chip (InGaAlP). Packaged in a Golden Dragon Plus LED, the chip emits at a wavelength of 615 nm. Currently, no LED at this wavelength has a higher efficiency. Its measured efficiency is 44 percent at 350 mA (49 percent at 70 mA), and it exceeds 50 percent efficiency at 350 mA for a wavelength of 642 nm.

The 30 percent increase in the efficiency of the diode results from improved material properties, further development of the thin-film platform and greater output efficiency. Unencapsulated chips benefit even more from the improvements.

Higher efficiency yields greater output for the same current and lower power consumption in all relevant applications. With this technology, new design options are possible, as fewer chips are needed for the same output. In addition, there is 50 percent less wasted thermal heat, so less cooling is required. As brightness increases, the light sources can be made increasingly smaller.

The improved performance of this thin-film LED technology expands the possible applications for this light source. For example, high-efficiency red can deliver warm-white LED solutions with better color rendering and improved energy balance by color mixing instead of typical phosphor conversion of blue light.

“This will benefit all applications that use high-efficiency red LEDs, particularly projection applications,” said Dr. Wolfgang Schmid, who is responsible for developing this chip technology at Osram Opto Semiconductors. “We expect to start equipping LED products with the new thin-film chips in about a year’s time.”

For more information, visit: www.osram-os.com