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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 49: Poster Session II

CPP 49.8: Poster

Dienstag, 17. März 2020, 14:00–16:00, P1A

Quantification of Phase Purity in Formamidinium Based Multiple-Cation Perovskites by X-ray Scattering — •Lena Merten, Alexander Hinderhofer, and Frank Schreiber — Institut für Angewandte Physik, Universität Tübingen, Germany

During the last decade, the material class of hybrid organic-inorganic perovskites aroused huge interest in the solar cell community, leading to a substantial rise in photovoltaic efficiency and a promising perspective for relatively cheap and easy to manufacture solar cell materials. Formamidinium (FA) used as a central cation has the advantage of enhanced light harvesting due to a relatively small band gap, however, α-FAPbI₃ is unstable at room temperature and decays into hexagonal δ-FAPbI₃. Mixing various organic and inorganic cations within the perovskite material is investigated as one means to achieve enhanced phase purity of the photoactive cubic perovskite phase.

We used grazing incidence x-ray diffraction^[1] to examine mixed cation perovskite thin films on mesoporous TiO₂ substrates with regard to their ability to stabilize FA based perovskite.

Addition of the inorganic cations Cs and Rb to mixed MA:FA hybrid perovskites was found to significantly reduce the amount of hexagonal phases and excess lead iodide phase. By varying the probing depth, differences in phase composition between the film surface and the bulk material could be observed. The presence of inorganic cations also affected the degree of orientational order, crystallite size and the lattice constant of the perovskite crystal structure.

[1] A. Greco et al.,J. Phys. Chem. Lett. 2018, 9, 23, 6750-6754