Researchers from the University of Potsdam and the Chinese Academy of Sciences have combined perovskite with organic absorbers to create highly efficient tandem solar cell.
The team explained that combining two materials that selectively absorb short and long wavelengths, e.g., blue/green and red/infrared parts of the spectrum, makes the best use of sunlight and is a well-known strategy to increase efficiency in solar cells. Best red/infrared absorbing parts of solar cells so far were, however, made from traditional materials, such as silicon or CIGS (copper indium gallium selenide), which require high processing temperatures, and thus exhibit a relatively high carbon footprint. In their work, the team combined perovskite and organic solar cells, both processed at low temperatures with a low carbon footprint.
Achieving a record level of 25.7% efficiency for this new combination, however, was not easy, says Felix Lang from the University of Potsdam: “This was only possible by combining two major breakthroughs.”
First, Meng and Li from the Chinese Academy of Sciences synthesized a novel red/infrared absorbing organic solar cell that extends its absorption even further into the infrared. “Still, tandem solar cells were limited by the perovskite layer, which shows strong efficiency losses if adjusted to absorb only blue/green parts of the sun spectrum”. “To tackle this, we utilized a novel passivation layer applied to the perovskite that reduces material defects and improves the performance of the whole cell.”
