Graphene model by James Hedberg
While silicon has long been the standard for commercial solar cells, new research from the Institute of Photonic Sciences (ICFO) in Spain has shown that graphene could prove far more efficient when it comes to transforming light into energy. The study found that unlike silicon, which generates only one current-driving electron for each photon it absorbs, graphene can produce multiple electrons. Though the application of graphene in solar cells is only theoretical, the potential outlined in the study is remarkable; solar cells made with graphene could offer 60% solar cell efficiency – double the widely-regarded maximum efficiency of silicon cells.
Graphene, which is comprised of pure carbon, has some fairly extraordinary properties—most notably that the single atom-thick sheets of it are ten times stronger than steel. Recent developments have seen the material applied to such diverse technologies as water purification and flexible batteries. But the Institute of Photonic Sciences study, published in Nature Physics, sought to explore the material’s ability to generate electrons upon absorbing light.
The ICFO team “used two ultrafast light pulses. The first sent a prescribed amount of energy into a single layer of graphene. The second served as a probe that counted the electrons the first one generated,” according to MIT Technology Review. What they uncovered was the first experimental proof that not only can graphene “work with every possible wavelength you can think of,” but that it is also substantially more efficient at converting light into energy.
Group leader at ICFO, Frank Koppens explained “It was known that graphene is able to absorb a very large spectrum of light colors. However now we know that once the material has absorbed light, the energy conversion efficiency is very high. Our next challenge will be to find ways of extracting the electrical current and enhance the absorption of graphene. Then we will be able to design graphene devices that detect light more efficiently and could potentially even lead to more efficient solar cells.”
Though the uncovered potential for graphene’s use in next-gen solar cells is particularly exciting, the researchers are “reasonably confident” that the their findings will likely first be used in the development of better light sensors—as MIT explains “like those used in cameras, night vision goggles, and certain medical sensors.”