Researchers at the EPFL, along with scientists from Luxembourg Institute of Science and Technology (LIST) have used microscopy with mass spectrometry to study the nanoscale elemental distribution of mixed perovskites, which is particularly relevant for photovoltaic reproducibility and efficiency.
Perovskite are usually deposited as thin films on a surface, and they self-organize into crystals capable of being used for efficient solar cells. Limited information is available about the self-organization of the material, or how the different elements distribute - all of which is vital for optimizing perovskite photovoltaics. This is why the team tried to reveal significant micro- and nanoscale elemental and structural properties in self-organizing mixed perovskite films.
The scientists used a unique combination of imaging methods (HIM and SIMS) to get chemical information about the perovskite film's surface together with a lateral resolution down to 10 - 20 nm. They also used Kelvin probe force microscopy in order to map local surface potential variations. Combined photoluminescence and Raman spectroscopy mapping finally revealed structural and optical non-homogeneities on the pervoskite.
The findings will hopefully help in optimizing the manufacturing of perovskite solar cells in the future, thus prompting the authors to state: "Our results provide unprecedented understanding of the nanoscale perovskite composition.'
