Specialty polymers play a role in solar-cell technology developed by a University of Toronto research group.
Professor Ted Sargent leads a group that found ways of capturing infrared light from sunlight and converting it into electricity. The technology could boost the energy-capturing efficiency of solar cells. Previous solar cells focused on capturing a narrow band of visible light.
Sargent's solar cell comprises a polymer matrix containing nanoparticles that capture infrared light. Nanoparticles that work include lead sulfide, arsenic sulfide and lead selenide. The polymer matrix in which the nanoparticles are suspended needs to be electrically conductive. When sunlight hits the cell, it jolts electrons out of the nanoparticles. The electron is carried by the conductive polymer to the cathode backing, typically made of magnesium, creating an electrical current.
Sargent said conductive polymers include certain polythiophenes. Not many conductive polymers can be processed by molding or extrusion, but most can be applied as solutions that become films when the carrier solvent evaporates. Thin films can be applied to a range of surfaces like paint, to create solar cells.
The technology can be used for more than solar cells. The nanoparticles' response to infrared light indicates uses in digital cameras that can see in the dark and medical imaging systems that can see through layers of skin.
Peter Peumans of California's Stanford University has not worked on Sargent's cells, but he reviewed the research group's results. He calculates that combining Sargent's infrared cell technology and existing solar technology could harness 30 percent of the energy in the sun's rays, vs. 6 percent for the current best polymeric solar cells for visible light.
Sargent said he is looking at launching a company via venture capitalists and at licensing options. He holds a research chair in the Electrical & Computer Engineering Department of the University of Toronto.