The U of T researchers, led by Professor Ted Sargent, report the first efficient tandem solar cell based on colloidal quantum dots (CQD). “The U of T 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,” said lead author Dr. Xihua Wang.
The team pioneered solar cells made using CQD, nanoscale materials that can readily be tuned to respond to specific wavelengths of the visible and invisible spectrum. 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. The work expands the Toronto team’s world-leading 5.6 per cent efficient colloidal quantum dot solar cells.
– from sciencedaily.com