Dr. Ted Sargent
Professor, Faculty of Applied Science and Engineering, University of Toronto
Over the past several years Ted has made a number of research breakthroughs which are paving the way for the widespread use of solar cells as an energy source. In 2005 Ted Sargent invented the first paint-on solar cell to harvest the sun’s abundant infrared rays. He then improved over ten-thousand-fold the performance of his new class of devices. His breakthrough solar cell significantly reduced costs associated with solar energy by enabling simple spray-coating of his semiconductor onto nearly any surface. Research-grade materials to make his solar cells cost less than $20 per square meter; in mass-production these costs will come down further. In contrast, silicon, in mass production, costs hundreds of dollars per square meter.
A few months ago Professor Sargent made an additional breakthrough in solar cell technology, creating the first efficient tandem solar cell based on colloidal quantum dots (CQD). The device is a stack of two light-absorbing layers—one tuned to capture the sun’s visible rays, the other engineered to harvest the half of the sun’s power that lies in the infrared spectrum. This is the first CQD solar cell which absorbs both infrared rays and visible rays on the same cell. By capturing such a broad range of light waves—wider than normal solar cells—tandem CQD solar cells can in principle reach up to 42 per cent efficiencies. The best single-junction solar cells are constrained to a maximum of 31 per cent efficiency. In reality, solar cells that are on the roofs of houses and in consumer products have 14 to 18 per cent efficiency. These should be commercially available within 5 years.