Ten years ago, LED Lighting was set to revolutionise the general illumination market. LEDs, also known as Light Emitting Diodes, had already taken over are the role as indicator panel illuminators and user interfaces on industrial, commercial and consumer products. All the trend lines indicated that they would eclipse the incandescent light globe for cost per watt within a decade.
So what went wrong?
More power without more light
As the technology was scaled up, the power levels rose and the expected requirements of more heatsinking were being dealt with and all seemed on track for LEDs to take over the world of lighting. But then a snag was hit. The technology got to a point where the efficiency dropped off as more current flowed through the diode. Companies like CREE, LumiLEDs and OSRAM pursued different and moderately successful strategies to try and overcome these limitations but the pace of progress slowed dramatically.
All of this points to a technical barrier we still don’t fully understand but are chipping away at.
Same light less cost
The other issue is the cost per watt in terms of the manufacturing cost of LEDs. The manufacturing process typically uses Sapphire or Silicon Carbide substrated which makes LEDs more expensive to manufacture than conventional semiconductors. There are several ways to improve this and they are all being pursued in parallel.
The first is the move toward organic semiconductors as covered in my recent post on Printed Electronics I looked at much lower cost techniques for making semiconductors and organic LEDs are one of the possible end products from these techniques. The CSIRO are world leaders in these technologies and are actively pursuing research into flexible electronics including organic displays and lighting. Here the challenge is creating a robust manufacturing technique that produces high volume, low cost lighting. The efficiency may not be as high but the cost per watt is much lower. Organic Semiconductors and organic LEDs will continue to be part of the solution. You can read about their efforts in CSIRO Flexible Electronics.
The second move is toward reducing the costs of conventional LED manufacture by eliminating the more costly steps of the process. A recent breakthrough was announced by Bridgelux and reportied in IEEE Spectrum will permit the manufacture of LEDs on silicon substrates. In Silicon Is Key to Quest for $5 LED Lightbulb the breakthrough is described and the promise is good. This also does not address the efficiency problem but again reduces the cost per watt.
Efficiency is the final frontier
The final chapter is yet to be written because the breakthrough we have all hoped for has not yet arrived. In the meantime the problem is being tackled from many sides and advances are being made on multiple technical fronts. LED lighting is an important part of the strategy to reduce our Carbon Footprint.
Ray Keefe has been developing high quality and market leading electronics products in Australia for nearly 30 years. For more information go to his LinkedIn profile at Ray Keefe. This post is Copyright © 2011 Successful Endeavours Pty Ltd.