Making White Light – materials research for a better world

Incandescent bulbs are one of the most energy-inefficient products in daily use,” Joanna McKittrick says. Touch a regular old 100-W light bulb after it’s been lit for a few minutes, and you’ll see what she means.

Less than 5% of the electrical energy that goes into the tungsten filament inside is converted to visible light, explains McKittrick, a luminescent materials specialist at the University of California, San Diego. The rest is wasted as heat that, should you follow our instructions, will burn your fingers.

Incandescents “basically haven’t changed since Thomas Edison invented them” about 140 years ago, she says.

Discovered via computational screening for new phosphors, this compound (above) is the first member of the previously unknown Sr-Li-Al-O crystal family. Black outline = unit cell. Gold = Sr. Red = Li. Green = Al. Blue = O.

Bulbs that contain light-emitting diodes (LEDs), on the other hand, can produce the same amount of white light but barely feel warm to the touch. That’s because LEDs are more energy efficient. A 15-to-20-W LED can produce the same brightness as a 100-W incandescent, roughly 1,500 lumens. LEDs are also less fragile and can last tens of thousands of hours longer. Nevertheless, these modern alternatives currently account for less than 10% of lighting worldwide, according to data from the U.S. Department of Energy.

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