A solar cell developed at the Unversity of Toronto, Canada, is able to harvest both visible and infrared light and can theoretically achieve efficiencies of up to 42 percent. Their tandem solar cell is based on colloidal quantum dots (CQD), and the team has been led by Professor Ted Sargent, a Professor of Electrical and Computer Engineering.
He describes the CQD as “a breakthrough in architecting the interface between the visible and infrared junction. The team engineered a cascade – really a waterfall – of nanometers-thick materials to shuttle electrons between the visible and infrared layers.”
Doctoral student Ghada Koleilat, who also works on the project, says: “We needed a new strategy – which we call the Graded Recombination Layer – so that our visible and infrared light-harvesters could be linked together efficiently, without any compromise to either layer.”
While normal single junction solar cells can only reach a theoretical maximum of 31 percent, the CQD solar cells can go up to 42. For the moment, though, they only achieved 5.6 percent, but hope that in less than five years they’ll be able to commercialize solar cells based on their invention.