Understanding Chemical Inhomogeneities and Cation Gradients in Perovskite Photovoltaics with TOF-SIMS

Time-of-flight secondary-ion mass spectrometry (TOF-SIMS) is one of the few techniques that can obtain chemical information from all components of hybrid organic-inorganic perovskite photovoltaics in up to three dimensions. This can yield critical insight into the uniformity of the cations through the thickness of the film (with sub-nm resolution), as well as laterally (with 100nm resolution) We have been using a TOF-SIMS to analyze perovskite photovoltaics at NREL for more than four years and have found many tricks and best practices, summarized here, to get around known artifacts when depth profiling and imaging.