A nanophotonic solar thermophotovoltaic device.
Traditional photovoltaic solar cells have an inherent limit on the efficiency at which they can convert sunlight into energy. This limit—based on the bandgap of the material used and known as the Shockley-Queisser limit—is about 33.7 percent for standard solar cells. It is essentially due to any material’s inability to respond to all wavelengths of sunlight; so what if there was a way to change the wavelengths that actually reach the cell to those it converts best? MIT researchers have unveiled the best-yet version of that idea, known as solar thermophotovoltaics.