technology SiGe
we could expect a 40% overall cost reduction in 5 years due to “standard” ingenuity. Examples of improvements of this type would be: Processing on larger substrates Increasing chip size Lower cost, higher throughput laser lithography Reduction in current density to reduce losses from droop, and improve efficacy
Optimise production for high yield Higher performance phosphors Filling the light-bulb form factor Innovations in thermal management Simplification of the electrical power interface
Figure 2. Lighting product display in a neighbourhood supermarket. The red and orange ovals identify incandescent and halogen while the green shows fluorescent. The lamps are primarily by Philips and Osram.
Incandescent lightbulbs will soon be a thing of the past. As they burn out, they will be replaced. The halogen lamp, which looks like an incandescent, and gives off the same quality of light and heat, is a possible replacement proposed by major lamp manufacturers. They are three times more expensive than incandescent bulbs, but last only twice as long. Many consumers may understand that this is an even more expensive choice. It is probable that most of the 12 billion lamp sockets world-wide, which now contain incandescent lamps, will be filled by CFL when the incandescent bulb burns out. Since the CFL lasts for 5 to 8 years, this sets the time by which manufacturers should have a competitively priced product. As another example, I visited a neighbourhood store where I am likely to go to buy a lamp. Space on the shelves is precious, and allotted only to products that sell. In figure 2 you can see that the lighting display is crowded, with 70% of the product space given to incandescent technologies and 30% to CFL. There were no LED lamps on display in this location.
Manufacturing cost reduction
The current application space for general lighting involving point sources like light bulbs, consists of 12 billion sockets (see Light’s Labours Lost, IEA, 2006). As incandescent lighting is being phased out, these sockets are being filled by principally by CFL replacements with a lifetime of 5 to 8 years. This lifetime creates a potential opening for LED general lighting sources. During the next five years, the costs of LED solutions need to drop by about 70% in order to reach competitive pricing levels.
The Haitz Laws observe trends in LED performance and cost. Currently the cost per lumen is dropping at about 10% per year. Extrapolating, using this rate tells us that
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www.compoundsemiconductor.net April/May 2010
The Haitz Laws also tell us that disruptive concepts will be needed. These may be based on continuous processing of LEDs, new synthetic substrates and alternatives to phosphors for wavelength conversion that would yield strictly repeatable colour temperature. The third key element in cost reduction will come from standards. Standards bring important cost reductions from manufacturers, while raising appeal for consumers. Many engineers are working on standards for LEDs. There are international bodies like the CIE, as well as national ones such as Energy Star in the United States. A feature of a good standard is its relevance to the application under consideration. Standards for automotive lighting are not the same as general lighting.
Conclusion
Following the ban on incandescent lamps for general lighting, LEDs will not capture this opportunity because there are not yet units that deliver performance at competitive pricing. The space will be filled by CFL and to some measure by halogen lighting substitutes. LEDs manufacturers will have a second opportunity to replace CFL lamps approaching the end of their product life. Manufacturers should achieve something like a 70% reduction in pricing over the next five years in order to capture this opportunity.
Standard learning-curve improvements will not be enough to reach this ambitious target. Substantial disruptive invention will be needed. Large LED manufacturers have also major investments in the competing technologies, and will continue to exploit the lighting solutions that generate the best return on investment. However, if the pricing of LEDs and CFL lamps becomes similar, there may be a chance to implement a ban on fluorescent lighting as a way to limit mercury proliferation in the environment. Finding a future for LEDs in the general lighting market depends on a complex mixture of elements most of which need substantial improvements: marketing, manufacturing methods, performance, technology and standards, being the most important.
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