The quest for the better light bulb has taken yet another leap. This time, nanotechnology derives light from atom-thin strips of one of the world’s strongest materials: graphene.
For the first time, scientists say they’ve created a flexible and transparent light source with carbon in its purest form. They say their discovery could also eventually transform computers by using light rather than electronic circuits in semiconductor chips.
“We’ve created what is essentially the world’s thinnest light bulb,” says Columbia University engineering professor James Hone in announcing the findings. He co-authored a study, published Monday on Nature Nanotechnology's website, by a team of researchers from South Korea, Columbia's Fu Foundation School of Engineering and Applied Science, Stanford University and University of Illinois at Urbana-Champaign.
Their approach is notable even in the rapidly changing world of light bulbs. In recent years, as the United States and other countries have moved to phase out Thomas Edison’s century-old incandescent, the market has moved toward much more energy-efficient compact fluorescent lamps (CFLs) and light-emitting diodes (LEDs)—and beyond.
Companies are offering new products. The Finally Light Bulb Companyuses induction technology for its warm-glowing super-efficient Acandescent alternative, and Alkilu has portable OLED (organic LEDs) lamps that, unlike other bulbs, don’t have a backlight.
Also, later this year, a graphene-coated LED that lasts longer and uses less energy than a typical LED is expected to enter the marketplace—the result of research at Britain’s University of Manchester. It’s not, though, a pure graphene light bulb. (Get the myths versus the facts on CFL and LED light bulbs.)
“They’re using the graphene to increase the heat dissipation. Our study shows light emission from the graphene itself,” says Young Duck Kim, a postdoctoral research scientist at Columbia who led the latest work.
Four years ago, he began observing light emissions from graphene, a newly discovered material that’s ultra lightweight but stronger than steel. He just didn’t know why it was happening.
His team found that passing a current through a filament containing small strips of graphene could reach temperatures of more than 2500°C (4532°F), which is high enough to produce visible light. It did so without melting the metal electrodes to which they were attached. The reason? As graphene heats up, it becomes a poor conductor of heat, so the high temperature stays confined to a small spot in the center. In contrast, micro-scale metal wires cannot withstand such extreme heat. (Take the quiz: What You Don't Know About Energy-Efficient Lighting.)
Their work takes a page from Edison’s playbook. “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,” says study co-lead author Yun Daniel Park, professor of physics and astronomy at Seoul National University, in a press release.
Kim says the team is seeking to commercialize the technology. He expects that could happen within five years, allowing manufacturers to use graphene to create flexible and transparent light displays.
He says Intel and IBM are tackling the difficult task of integrating light into their computer chips. He expects that within about 10 years, his team’s work with graphene could also help make this a commercial success.