Two teams of solar-power engineers, one led by a large group at the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH and the other by a group at the École Polytechnique Fédérale de Lausanne, have found two ways to make silicon and perovskite work better together to increase the efficiency of solar cells. The specifics of their work, as well as the outcomes of their tests, have been detailed in papers that have been published in the scientific journal Science. The King Abdullah University of Science and Technology’s Stefaan De Wolf and Erkan Aydin have written a Perspectives article for the same issue of the journal that details the work done by both teams.
Due to silicon limitations, only a small portion of the sunlight frequency band can be converted into electricity, limiting its theoretical efficiency to 29.4%, according to previous research. Solar engineers have attempted to overcome this limitation by layering on additional materials that are capable of converting light at other frequencies into electricity.
Perovskite, a crystal formed from a mixture of calcium and titanium, is one such material. It has potential, but its tendency to allow some electrons to be reabsorbed into the crystal before they can be used to generate electricity limits its utility. In these two new endeavors, the teams have each devised a unique strategy to circumvent the issue.
The engineers started by injecting liquid piperazinium iodide into a perovskite layer that had already been applied to a silicon layer. During testing, their method proved to be 32.5% effective.
In the second attempt, the team came up with a methodthat involved coating a silicon layer with precursor chemicals and then adding a second chemical to start a reaction that produced a perovskite coating. The outcome was a covering with diminished surrenders that permitted fewer electrons to meander once more into the precious stone. The two-step process could be used to make solar cells that were 31.2% efficient, according to tests.
Both teams acknowledge that their methods were used on much smaller solar cells than those used in commercial applications. As a result, before either could be used for conventional solar-cell applications, they needed to be scaled up.
More information: Xin Yu Chin et al, Interface passivation for 31.25%-efficient perovskite/silicon tandem solar cells, Science (2023). DOI: 10.1126/science.adg0091
Silvia Mariotti et al, Interface engineering for high-performance, triple-halide perovskite–silicon tandem solar cells, Science (2023). DOI: 10.1126/science.adf5872
Stefaan De Wolf et al, Tandems have the power, Science (2023). DOI: 10.1126/science.adi6278
