Measuring the True Efficiency of Blue LEDs: Absolute vs. Relative Comparison.

The assumption that the internal quantum efficiency (IQE) of blue light-emitting diodes (LEDs) is always 100% is wrong, according to a new study from University of Illinois Urbana-Champaign Electrical and Computer Engineering researchers. The IQE of an LED can be as low as 27.5%. To meet the efficiency standards laid out by the DOE, it will be increasingly important to properly quantify the efficiency of LEDs.