What Happened to LED Light Bulbs?
June 29, 2009
Light-emitting diodes are making their way into everyday life [see “In Pursuit of the Ultimate Lamp”; SciAm, February 2001]. Still, LED versions of 60-watt incandescent bulbs can cost around $100. Scientific American magazine states that just this month engineers at Purdue University reported that they have developed a way to make cheaper blue LED’s. Blue LED’s, along with easier to produce red and green LED’s, are needed to
generate white light. Researchers describe making LED’s on silicon with a built-in reflective layer, which reduces cost. With mass manufacturing they predict that affordable LED lamps could appear in two years.
Why LED’s? LED’s are very efficient at producing light from electricity. Unlike incandescent (filament) light bulbs in which only approximately 20% of the electrical energy is converted to visable light and the other 80% is radiated as thermal energy, nearly all of the electrical energy is converted into visable light. Also, the average incandescent or fluorescent light bulb has a lifetime use of hundreds of hours. LED’s have a lifetime use of tens of thousands of hours.
