Ultra-high Efficiency Blue LEDs

High efficiency is one of the goals driving the development of LEDs for lighting, television and mobile devices. Since the display, including backlight, on a mobile device like a smartphone is one of the major consumers of power, any increase in the efficiency of blue LEDs, the basis for the white LEDs commonly used in backlights, is important to anyone concerned about battery life of his smartphone.

A paper (DOI: from the University of California, Santa Barbara was published last November by Ben Yonkee, a graduate student under Professor Shuji Nakamura. Dr Nakamura won the Nobel Prize in 2014 for some of the original work on GaN LEDs and is listed as one of the four co-authors. The report discusses blue LEDs with an output of 450 nm and an overall wall plug efficiency of about 70%. The authors both normal and flip-chip versions of their technology.

LED Efficiency Flip chip resizeExternal Quantum Efficiency and Wall Plug Efficiency of the flip-chip version of the blue LED

While the non-flip-chip version has slightly higher efficiency at low currents than the flip-chip version shown in the figure, the flip-chip can be driven to higher power levels so fewer LEDs would be needed in a backlight. While this paper represents university research at this point, reading the paper I see nothing that can’t be commercialized. Since Dr. Nakamura and some of the other co-authors founded Soraa to make GaN LEDs, this technology might first appear from that company. – Matthew Brennesholtz