Nature Photonics published a paper about a new type of solar cell that uses cost-effective coatings to effectively produce electricity from sun rays. The U of T engineering research team headed by Professor Ted Sargent, electrical and computer engineering professor, University of Toronto, discovered the first effective tandem solar cell using colloidal quantum dots (CQD).
Dr. Xihua Wang, lead author stated that this equipment consists of a pair of light-absorbing layers, one of which is capable of absorbing the visible sun rays and the other for capturing half of the infrared rays emitted by sun.
Sargent reported that it was important to form an interface between the junction of visible and infrared rays. They developed a cascade using materials that was nanometers thick, almost like a waterfall, to transfer electrons between the two layers. Ghada Koleilat, a doctoral student, suggested that a new approach called the graded recombination layer that perfectly joined the harvesters of visible and infrared light without compromising any of the layers.
U of T researchers developed solar cells based on CQD using nanoscale materials that are suitably adjusted to respond to specific visible and invisible spectrum wavelengths. Tandem CQD solar cells are 42% efficient in capturing a wide range of light rays better than normal solar cells. A good single-junction solar cell is 31% efficient. In usage, roof-top solar cells in houses and commercial buildings show 14 to 18% efficiency. Toronto team developed colloidal quantum dot solar cells that are 5.6% efficient.
Sargent expects that within five years solar cells with the graded recombination layer will be incorporated into automobile components, construction materials, and mobile devices. Both the world and the solar community require a 10% efficient solar cell that significantly improvises price rates of photovoltaic element, he added. This advancement paves the way for high-efficiency solar cells that utilize varied photons from the sun’s rays.
Source: http://www.utoronto.ca