Synchrotron Radiation Applied to the Characterization of Perovskite Films: Morphology, Structure and Composition
Ana Flavia Nogueira a
a Laboratory of Nanotechnology and Solar Energy, Institute of Chemistry, University of Campinas – UNICAMP, P.O. Box 6154, Campinas, 13083-970, Brazil
nanoGe Perovskite Conferences
Proceedings of nanoGe International Conference on Perovskite Solar Cells, Photonics and Optoelectronics (NIPHO19)
International Conference on Perovskite Thin Film Photovoltaics
Jerusalem, Israel, 2019 February 24th - 27th
Organizers: Lioz Etgar and Kai Zhu
Invited Speaker, Ana Flavia Nogueira, presentation 003
Publication date: 21st November 2018

Organic inorganic hybrid perovskites (OIHP) is the most promising material to achieved high power conversion efficiency (PCE) at low cost. The high-quality optoelectronic properties in combination with solution-based preparation methods are responsible for the currently certified PCE record of 23.3%, which is close to the PCE of single crystal silicon solar cells (26.1%). OIHP is generally labelled as an ABX3compound, where A is a monovalent cation such methylammonium (MA), formamidinium (FA), or cesium (Cs), B is a divalent metal, such lead (Pb) or tin (Sn), and X is a halide anion, bromide (Br), iodide (I-). The properties of the perovskite film are direct related to film morphology, composition and crystalline structure, thus a clear understanding of how and when the intermediate and the perovskite phases are forming, as well the distribution of these multiple phases in the bulk and grains boundaries are important questions to be addressed in order to improve perovskite film properties and consequently the PCE of the devices. In this presentation, we will summarize our most recent results using in situtime-resolved grazing incidence wide angle x-ray scattering (GIWAXS) and synchrotron infrared nanospectroscopy (nano-FTIR). GIWAXS experiments allowed us to understand the influence of the relative humidity, type of solvent and time to drop the antisolvent during the preparation of mixed cation perovskite films. We also identified intermediates formed before and during the spin coating process. Nano-FTIR technique was applied for the first time on OIHP. Our results revealed a spatial heterogeneity of the vibrational signal, which are associated to different chemical composition. The nano-FTIR permitted to access grain-to-grain chemistry of OIHP and the identification of PbI2and hexagonal phases which are distributed randomly in a background formed by cubic (black phase) perovskite.

Fapesp, Shell, CNPEM, INEO

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