Dresden 2017 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 24: Fundamentals of Perovskite Photovoltaics IV (jointly with CPP/HL)
DS 24.4: Vortrag
Dienstag, 21. März 2017, 15:00–15:15, ZEU 222
Optical phonons in methylammonium lead halide perovskites and implications for charge transport — •Michael Sendner1,2, Pabitra K. Nayak3, David A. Egger4, Sebastian Beck1,2, Christian Müller1,2,5, Bernd Epding2,5, Wolfgang Kowalsky1,2,5, Leeor Kronik4, Henry J. Snaith3, Annemarie Pucci1,2, and Robert Lovrincic2,5 — 1Kirchhoff-Institut für Physik, Universität Heidelberg — 2InnovationLab, Heidelberg — 3Clarendon Laboratory, University of Oxford — 4Department of Materials and Interfaces, Weizmann Institute of Science — 5Institut für Hochfrequenztechnik, TU Braunschweig
Recent reports indicated that the mechanical and electronic properties of lead-halide perovskites are strongly affected by the lattice vibrations. Herein we report far-infrared spectroscopy measurements of CH3NH3Pb(I/Br/Cl)3 thin films and single crystals at room temperature (RT) and a detailed quantitative analysis of the spectra. We find strong broadening and anharmonicity of the lattice vibrations for all three halide perovskites, which indicates dynamic disorder
of the lead-halide cage at RT. We determine the frequencies of the transversal and longitudinal optical phonons, and
use them to calculate, via appropriate models, the static dielectric constants, polaron masses, electron-phonon coupling constants,
and upper limits for the phonon-scattering limited charge carrier mobilities. Within the limitations of the model used, we can place an upper limit of 200 cm2V−1s−1 for the RT charge carrier mobility in MAPbI3 single crystals.
See also: Sendner et al., Materials Horizons, 3, pp 613-620, 2016.