Osram greatly improves the efficiency of green LED and improves the battery life of fitness tracker

The significant decline in light output (green gap phenomenon) exhibited by green LED is often the cause of efficiency problems and high cost in customer applications. For its indium gallium nitride (InGaN)-based green LED, Osram Optoelectronic Semiconductor has successfully reduced the typical forward voltage by about 600 mV. With the simultaneous growth of optical output power, customers immediately benefit from an efficiency increase of up to 40% compared with the previous generation products in Osram's entire UX: 3 product portfolio.

OSRAM Optoelectronic Semiconductor has now successfully reduced the typical forward voltage of green LED, and the developers of Osram Opto Semiconductors managed to reduce the typical forward voltage of green direct emitting InGaN LED with power density of 45 A/cm 2 by 600 mV to 2.6 V. The benefits are considerable, especially in applications using a combination of red, blue and green LED. Since voltages are now less than 3 V for all three colors, drivers previously designed for higher maximum voltages can now be reduced in size. This in turn reduces dissipative power loss and cost. The key factor to improve the efficiency is to improve the charge carrier transport and optimize the material quality in the epitaxial layer.

With the new technology, the efficiency of 175 lm/W at the wavelength of 350 mA, 1mm2UX: 3 chip near 530 nm can be achieved. At 1 A pump current, the absolute light output exceeds 300 lumens, bringing new applications to customers.

"Until recently, these efficiency values seemed unachievable for green direct-emitting InGaN LEDs. Now we are entering a field that can only be achieved by using phosphor conversion emitters so far, but the spectral quality is obviously reduced. Thanks to the success of our development team, we have been able to significantly reduce the green gap for our customers, "said Adam Bauer, project manager of Osram Optoelectronic Semiconductor. The team is currently making further improvements, which provide obvious potential for recent research results.