Crystal Orientation and Grain Size: Do They Determine Optoelectronic Properties of MAPbI3 Perovskite?
Loreta Muscarella a, Eline Hutter a, Sandy Sanchez b, Christian Dieleman a, Tom Savenije c, Anders Hagfeldt b, Michael Saliba d e, Bruno Ehrler a
a Center for Nanophotonics, AMOLF, The Netherlands, Science Park, 104, Amsterdam, Netherlands
b Ecole Polytechnique Fédérale de Lausanne EPFL, Laboratory of Photomolecular Science, Institute of Chemical Sciences and Engineering, Station, 6, Lausanne, Switzerland
c Delft University of Technology, The Netherlands, Julianalaan, 136, Delft, Netherlands
d Technical University of Darmstadt, Jovanka-Bontschits-Straße, 2, Darmstadt, Germany
e IEK-5 Photovoltaik, Forschungszentrum Jülich GmbH, Germany, 52425 Jülich, Germany
Poster, Loreta Muscarella, 079
Publication date: 25th November 2019

Growing large, oriented grains of perovskite often leads to efficient devices, but it is unclear if properties of the grains are responsible for the efficiency. Domains observed in SEM are commonly misidentified with crystallographic grains, but SEM images do not provide diffraction information. We study methylammonium lead iodide (MAPbI3) films fabricated via flash infrared annealing (FIRA) and the conventional antisolvent (AS) method by measuring grain size and orientation using electron back-scattered diffraction (EBSD) ) combined with a direct electron detector which allows the use of low specimen current compared to conventional detector resulting suitable for beam sensitive materials as perovskite. We study how grain size and crystal orientation affect optoelectronic properties such as local photoluminescence (PL), charge carrier lifetimes, and mobilities. We observe a local enhancement and shift of the PL emission at different regions of the FIRA clusters, but we observe no effect of crystal orientation on the optoelectronic properties. Additionally, despite substantial differences in grain size between the two systems, we find similar optoelectronic properties. These findings show that optoelectronic quality is not necessarily related to the orientation and size of crystalline domains. Furthermore, our findings offer a powerful tool as EBSD to pave future investigation towards understanding optical and electrical properties as a function of crystallographic orientation for perovskite thin films.

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