Researchers enhance durability of low-cost solar cells made from nano-sized crystals

U of T Engineering post-doctoral researcher Chongwen Li holds up a sample of an inverted perovskite solar cell An international team of researchers has developed a new technique to enhance the durability of inverted perovskite solar cells - an important step toward commercialization of an emerging photovoltaic technology that could significantly reduce the cost of solar energy. Unlike traditional solar cells, which are made from wafers of extremely high-purity silicon, perovskite solar cells are built from nano-sized crystals. These perovskite crystals can be dispersed into a liquid and spin-coated onto a surface using low-cost, well-established techniques. It is also possible to tune the wavelengths of light that get absorbed by the perovskites by adjusting the thickness and chemical composition of the crystal films. Perovskite layers tuned to different wavelengths can even be stacked on top of each other, or on top of traditional silicon cells, leading to "tandem" cells that absorb more of the solar spectrum than today's devices. The latest work,  published in the journal  Science , included researchers from the University of Toronto, Northwestern University, the University of Toledo and the University of Washington. "Perovskite solar cells have the potential to overcome the inherent efficiency limitations of silicon solar cells," says study co-author  Ted Sargent , who recently joined the department of chemistry and the department of electrical and computer engineering at Northwestern University but remains affiliated with University of Toronto Engineering, where he has a research lab.