By substituting metal-coated silicon for the sapphire-coated substrates used to make white light LEDs, researchers at Purdue University have found a way to reduce the cost of the devices, making them more practical for general lighting applications. The Purdue researchers have developed a technique to create LEDs on low-cost, metal-coated silicon wafers.
Incandescent lamps are about 10 percent efficient, meaning they convert 10 percent of electricity into light and 90 percent into heat. Their significantly better heating than lighting performance was long accepted as an unwanted but necessary byproduct of electric light. White LEDs offer efficiency ranging from 47 to 64 percent, but at a high cost: the LED lights now on the market cost about $100.
When the cost of a white LED lamp comes down to about $5, LEDs will be in widespread use for general illumination. LEDs are still improving in efficiency. Everything looks favorable for LEDs, except for that initial cost, a problem that is likely to be solved soon.