Improvements In LED Efficiency Droop

LED lighting has been on the rise for some time now but it wasn’t until 2014 when the Auger effect was identified as the principal cause of LED “efficiency droop” that the real potential revealed itself.

What is the Auger Effect? The Auger Effect is named after physicist Pierre Auger who was one of the principal researchers involved in its discovery. It describes a phenomenon where an outer shell valence electron moves into a vacancy in an inner shell accompanied by the release of energy. The released energy is typically emitted as a photon or another electron that is ejected from the atom. Here is a short YouTube video on the process:

What is Efficiency Droop? Efficiency droop refers to a phenomenon (now known to be caused by the Auger Effect) where LED efficiency drops off significantly when high current is run through the light. For this reason LEDs have had wide application in small devices like circuit boards but were only beginning to find wide acceptance in larger lighting applications like outdoor parking lot or street lighting, warehouse lighting, or sporting complex lighting. That is all changing with the discovery of the Auger effect and improvements are coming out rapidly now that the technology is properly understood.

Is there any advantage to the fact that LEDs have lower efficiency as the current run through them goes up? Yes, this can actually be a positive if you look at it from the other side of the coin. Say that you’re happy with the energy efficiency of your LED lights at full strength but want to improve your system efficiency by dimming them at certain times during the evening (e.g. during low traffic situations or unused floors in an indoor parking garage). Since LEDs improve their efficiency (and also their lifespan) as you dim the lights there is an incentive for operators and facility managers to run them responsibly (only as required). Compare this to metal halide lamps (traditionally used in outdoor lighting and warehouse applications). With metal halides the efficiency actually decreases as the lights are turned down. This being the case, it’s a lot more difficult to find the optimal operating power to maximize light quality for the situation but minimize the energy consumption.

Efficiency droop has generally been a limitation because the tremendous energy efficiency advantages of LEDs didn’t manifest as significantly in larger applications where high power is required. The efficiency advantages of LED lighting have traditionally fallen off as the current applied to the device rises. That is changing now that scientists understand what causes the phenomenon. Accordingly, the pace at which LEDs are expected to improve has tremendous potential to change the entire lighting industry for the better.

What is the future of LEDs now that the Auger Effect is Understood? LEDs have been on the rise for quite some time. That said, other lighting technologies have also been improving. Perhaps the most significant positive indicator for LEDs is the fact that the underlying technology is improving faster than it is in competing lighting technologies. Discovery of the Auger Effect is one indicator of this. Another positive indicator is growth in the semiconductor industry. According to the Semiconductor Industry Association (SIA), “[the semiconductor] market [is] projected to grow by 1.4 percent in 2016, and 3.1 percent in 2017.” All in all it looks like a bright future for LED lighting.

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