Regensburg 2016 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 80: Hybrid and Perovskite Photovoltaics IV (Joint session of CPP, DF, DS and HL, organized by HL)
HL 80.10: Talk
Thursday, March 10, 2016, 17:30–17:45, H2
Infrared spectroscopic study of vibrational modes and water infiltration in methylammonium lead halide perovskites — •Michael Sendner1,2, Christian Mueller1,2,3, Tobias Glaser1,2, Annemarie Pucci1,2, Wolfgang Kowalsky1,2,3, and Robert Lovrincic2,3 — 1Kirchhoff-Institut für Physik, Universität Heidelberg — 2InnovationLab GmbH, Heidelberg — 3Institut für Hochfrequenztechnik, TU Braunschweig
The interactions of the organic cation with the inorganic lattice in organo-metallic halide perovskites influence the vibrational properties of the cation which can be measured in the mid infrared (IR) spectral region. We determined the infrared optical properties of different methylammonium lead halide perovskite films (CH3NH3Pb(I/Br/Cl)3) and derived the full dielectric function [1]. The peaks of the vibrational modes are assigned by means of the comparison with MP2 calculated modes of the free methylammonium cation. The influence of the inorganic cage and the processing is discussed. Furthermore, we utilize IR spectroscopy to investigate the influence of water onto perovskite thin films. We show that the infiltration of water into CH3NH3PbI3 appears much faster and at much lower humidity than previously known [2]. We suggest a molecular picture of this infiltration where water molecules have a strong impact on the hydrogen bonding between the methylammonium cations and the surrounding Pb-I cage. [1] T. Glaser et al. J. Phys. Chem. Lett. 2015, 6 (15), 2913-2918 [2] C. Müller et al. Chem. Mater., 2015, 27 (22), 7835-7841