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DS: Fachverband Dünne Schichten
DS 20: Poster
DS 20.3: Poster
Mittwoch, 7. September 2022, 16:00–18:00, P3
Insights into the evaporation behaviour of FAI: material degradation and consequences for perovskite solar cells — Martin Kroll1, Seren Dilara Öz3, Zongbao Zhang1, Ran Ji1, •Tim Schramm1,2, Tobias Antrack1, Yana Vaynzof1,2, Selina Olthof3, and Karl Leo1 — 1Dresden Integrated Center for Applied Physics and Photonic Materials, IAPP — 2Center for Advancing Electronics Dresden, CFAED — 3Department of Chemistry, University of Cologne
Thermal co-evaporation is a promising method for large-scale uniform perovskite deposition. In this work, we look at the decomposition of formamidinium iodide (FAI) upon evaporation in high vacuum by tracking the composition of the residual gas with a mass spectrometer. We find that the precursor material degrades during the evaporation process into hydrogen cyanide (HCN) and sym-triazine (C3H3N3), leading to an increase in pressure, which is commonly observed during the deposition of FAI. Using optical characterization as well as x-ray photoelectron spectroscopy on co-deposited perovskite films, we demonstrate that this background pressure strongly affects the resulting film*s stoichiometry. Using two different vacuum setups, we are able to show that significant changes are imposed, e.g. on the optimized co-evaporation rates, by the specific vacuum chamber setup. Our results have important implications for the optimized evaporation of FA-based perovskites as they identify key issues related to the deposition of the FAI precursor.