Photovoltaic solar cells using multiple layers to absorb more sunlight is nothing new, the PV cells and arrays used for satellites and concentrated PV devices have been using them for years. But these are expensive devices that use rarer, expensive materials, making them too expensive for more common applications. That might be changing.
Stanford University and MIT researchers today (March 24) reported that they created a new kind of tandem PV cell using less expensive layering materials—silicon and perovskite crystals. The first is the used in the most common type of PV module while the latter is among the more promising technologies for less expensive solar cells.
“Perovskites have been studied for potential electronic uses including solar cells, but this is the first time they have been successfully paired with silicon cells in this configuration,” MIT said.
The perovskite can absorb higher-energy particles of light than most silicon PV devices can, according to the researchers. “Different layers absorb different portions of the sunlight,” said graduate student Jonathan Mailoa.
The same team of researchers, which also included MIT Professor of Mechanical Engineering Tonio Buonassisi as well Colin Bailie and Michael McGehee at Stanford, published research earlier this year on another tandem PV cell design. However that device used two separate electrical connections, one for each layer. The new design integrates the electronics between both layers. “It has advantages in terms of simplicity, because it looks and operates just like a single silicon cell,” Mailoa said.
In the new device, however, current produced by the cell is ultimately limited by the capacity of the lesser of the two layers. To reduce that impact, the group is trying to match the output of each layer as close as possible. The test device had a efficiency level of 13.7 percent but the researchers anticipate the efficiency of such cells could reach about 30 percent or ultimately more than 35 percent.
The researchers published their work in Applied Physics Letters. The research was supported by the Bay Area Photovoltaic Consortium and the U.S. Department of Energy.Tweet