Berlin 2018 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 61: Focus: Fundamental Physics of Perovskites II - organized by Lukas Schmidt-Mende and Vladimir Dyakonov
CPP 61.11: Vortrag
Donnerstag, 15. März 2018, 12:45–13:00, C 130
Structure and electronic properties characterization of CH3NH3PbI3−xClx mixed halide perovskite films upon massive solvents exposure — •Maryline Ralaiarisoa1, Yerila Rodriguez2, Ingo Salzmann1, Lidice Vaillant2, and Norbert Koch1 — 1Humboldt-Universität zu Berlin, Institut für Physik & IRIS Adlershof — 2Physics Faculty, University of Havana
We combined photoelectron spectroscopy (PES), grazing incidence X-ray diffraction, UV-Vis absorption spectroscopy, and atomic force microscopy to characterize the effect of massive solvent exposure on CH3NH3PbI3−xClx mixed halide perovskite films. We selected solvents that can potentially be used to solution-deposit organic charge transport layers on top of the perovskite: water, dimethylformamide (DMF), chloroform (CF), and chlorobenzene (CB). Water and DMF instantly dissolved the perovskite films. Particularly, water degraded the perovskite film into a yellow PbI2 film, along with the generation of reduced Pb0 precipitates. Furthermore, PES results indicate the presence of methyl ammonium or related compounds even after water dissolution. Although the crystal structure and morphology of perovskite films were preserved upon CF and CB exposure, the valence band and therefore the electronic properties of the films were strongly altered, as a result of surface state modifications. In fact, the film surfaces become less n-type upon exposure, possibly due to a reduction of surface Pb0-species. Thus, the use of CB and CF for solution deposition of organic charge transport layers is possible, but can already substantially modify the perovskite properties at the interface.