Infrared LED prototype sets efficiency record

December 05, 2012 // By Christoph Hammerschmidt
Osram claims a new efficiency record for an infrared LED chip: In the lab, the prototype achieved an efficiency of up to 72 percent. With a wavelength of 850 nanometers the chip has been designed in particular for infrared illumination applications.

At 930 milliwatts from an operating current of 1 A, its light output under laboratory conditions is 25 percent higher than that of the chips currently available on the market, lighting systems vendor Osram claims. The efficiency was measured at room temperature and at a dc current up to 1 A.

The results from Osram's R&D laboratory in Regensburg have created a new milestone. The prototype of a 1 mm 2 chip in infrared thin-film chip technology has achieved an efficiency of 72 percent from an operating current of 100 mA. This efficiency, known as wall plug efficiency (WPE), indicates the ratio of radiated power to electrical input power. 

Figure 1: Efficiency versus current of Osram's IR LED prototype .

The external quantum efficiency (EQE), in other words the probability of creating a photon and its emission from the LED chip per electron, is as high as 67 percent and remains above 64 percent up to an operating current of 1 A.

The wavelength of the chip prototype of 850 nanometers is required for infrared illumination applications, particularly for surveillance tasks and use with CCTV cameras. Osram also sees potential safety applications in the automotive sector, such as precrash sensors and illumination sources for night vision systems.

The method to increase the efficiency and brightness at the infrared LED prototype can be applied to other wavelengths as well, Osram said. This creates the perspective of implementing energy-efficient IR lighting solutions with fewer components in multi-chip applications. Under the bottom line, this would result in cheaper solutions which at the same time consume less energy.

The IR chip is expected to go into series production between in the first half of 2013, the company announced.