Scientists have created an ultra-thin light bulb using an atomically thin form of carbon, call graphene.
This incredible new light bulb could lead to faster communication devices and thin, flexible computer displays, the University of Texas at Austin reported. The device was created by attaching tiny strips of graphene to metal electrodes. The strips were then suspended above a silicon chip and passed through filaments, causing them to get hot.
"We've created what is essentially the world's thinnest light bulb," said James Hone, a professor of mechanical engineering at Columbia University and co-author of the study.
Thomas Edison used carbon as a filament for the first light bulb, and the researchers took a similar approach. They used carbon graphene, which has an ultimate size limit of one atom of thickness, and measured the light output achieved while applying a range of voltages.
"It was exciting to be able to see such bright, visible light from this device with my own eyes," said Yujin Cho, a doctoral student in physics at The University of Texas at Austin who worked on the project as a student in South Korea.
Creating "light on a chip" is important for the development of photonic circuits (which substitute electric currents for light). This has been achieved for a number of light sources, but the incandescent light bulb has proven difficult because its primary filaments are too hot for micro-scale metal wires to withstand. The heat transfer from the hot filaments can also lead to damage to the chip itself.
To overcome this, the researchers measured the spectrum of light emitted from the graphene, and found it reached temperatures above 4,500 degrees Fahrenheit, which is hot enough to glow brightly. The graphene was able to reach these high temperatures without melting the substrate or the metal electrodes, because as graphene heats up it becomes less and less efficient at conducting heat. This means the high temperatures remain confined to a small "hot spot," leading to a new light source that is 1,000 times more energy efficient than graphene on a solid silicon chip.
In the future, the researchers hope to further improve the qualities of these devices, such as speeding up the rate at which they can be turned on and off and developing ways to integrate them into flexible substrates.
The findings were published in a recent edition of the journal Nature Nanotechnology.
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