Current solar cell technology, using silicon as the base, has a theoretical limit to its efficiency, which falls somewhere around 30%, but solar cells made with graphene may push that limit up to somewhere around 60%.
The results of a study from researchers at the Institute of Photonic Sciences suggest that graphene might be the material of choice for the next generation of photovoltaic cells, as it is “highly efficient” at generating electrons from light.
When hit by light, silicon generates just one electron for each photon absorbed, which is only a fraction of the potential energy in the photon. But graphene generates multiple electrons for each photon absorbed, and if used in solar cells in the future, could boost the efficiency of those cells up to 60% or more, according to MIT Technology Review.
The study, “Photoexcitation cascade and multiple hot-carrier generation in graphene”, which was published in Nature Physics, found that graphene has a great potential for converting energy from light:
“Graphene is able to convert a single photon that it absorbs into multiple hot electrons, and that the higher photon’s energy, the larger the number of hot electrons created. Since these light-induced electrons can drive currents, hot-electron multiplication is an essential ingredient for light harvesting with very low energy loss. Moreover, the combination of broadband absorption and hot-carrier multiplication enables graphene to efficiently convert light energy from the full solar spectrum into electricity. “
Graphene was already known to be a versatile material, with a wide variety of properties that can be utilized in next-generation technologies, and previous efforts have been made to use graphene in ultra-thin, flexible solar cells, but with limited efficiency.
The authors of this most recent research conclude that while they still have some ways to go to get to a marketable graphene solar cell, there is a lot of potential for future development:
“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 could generate efficient solar power.”
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