Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 46: Poster Session IV

CPP 46.3: Poster

Mittwoch, 14. März 2018, 11:00–13:00, Poster A

In-situ monitoring of sequential conversion of MAPb(IxBr1-x)3 — •Carolin Rehermann, Katrin Hirselandt, Aboma Merdasa, and Eva Unger — Helmholtz-Zentrum Berlin, Young Investigator Group Hybrid Materials Formation and Scaling, Berlin, 12489, Germany

Metal halide perovskites are an interesting material for tandem solar cells due to their band gap tunability, band gaps up to 3 eV can be prepared by exchanging halides.1 Burschka et al.2 introduced the 2-step method. Three competing processes might occur: direct conversion/intercalation, dissolution-reformation and ion exchange.3

In this work, the second step is monitored by in-situ UV-vis measurements. The second step is the conversion from a lead iodide film into a mixed halide perovskite film MAPb(IxBr1-x)3. Using MABr we can track the different conversion kinetics between a direct conversion and a dissolution-reformation process. The influence of different reaction parameters is investigated.

In-situ UV-vis measurements show an initial evolution of a spectral signature characteristic for the absorption onset of the direct conversion product, MAPbBrI2. Upon progression, this signature disappears in favor of the pure dissolution-reformation product MAPbBr3. Changes in spectral signature during a post-conversion annealing step prove that ionic equilibration occurs.

1. Unger et al. Journal of Materials Chemistry A 2017, 5 (23), 11401-11409. 2. Burschka et al. Nature 2013, 499 (7458), 316-319. 3. Ko et al. Chemistry of Materials 2017, 29 (3), 1165-1174.