Nearly a month after the DOE conducted research to scale graphene up, a separate team of researchers from Columbia University, Seoul National University and the Korea Research Institute of Standards and Science has scaled graphene down to the size of an atom to create the world’s smallest lightbulb. Graphene, which is 200 times stronger than steel, is made of layers of carbon laid down in a lattice structure, and is a great electric conductor.
“Edison originally used carbon as a filament for his light bulb and here we are going back to the same element, but using it in its pure form — graphene — and at its ultimate size limit — one atom thick,” said Dr. Yun Daniel Park, professor in the department of physics and astronomy at Seoul National University and co-lead author of the study.
The thin layer of graphene was turned into a filament, similar to a thin wire of an incandescent light bulb. The scientists applied a 2-to-3-volt charge to the graphene suspended between two electrodes. By measuring the spectrum of the light emitted from the graphene, the team was able to show that the material was reaching temperatures above 2500 degrees Celsius, which made it hot enough to glow and become visible to the naked eye. The high temperatures were confined to a tiny “hot spot” and did not damage the silicon chip where it was mounted.
The researchers found the spectrum of the emitted light showed peaks at specific wavelengths due to interference between the light emitted directly from the graphene and light reflecting off the silicon substrate and passing back through the graphene.
“This is only possible because graphene is transparent, unlike any conventional filament, and allows us to tune the emission spectrum by changing the distance to the substrate,” explained Dr. Young Duck Kim, Columbia professor and another co-author of the study.
Graphene’s light-emitting properties could be used for a number of applications. It could be a light source for future computer chips or thin, flexible and transparent displays. It could also be the basis of a switching mechanism in future computers, using light instead of electricity to relay information.
“We can turn the light in graphene on and off very fast, which means we can send information very fast,” said Dr. Kim.
In addition to computers, the research may one day be applied to smartphones, cars, buildings and satellites. Read the full study, Bright visible light emission from graphene, on Nature Nanotechnology’s online journal.