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Charge Carriers Are Not Affected by the Relatively Slow-Rotating Methylammonium Cations in Lead Halide Perovskite Thin Films

Journal Article (2019)
Author(s)

Valentina M. Caselli (TU Delft - ChemE/Opto-electronic Materials)

Mathias Fischer (University of Würzburg)

Daniele Meggiolaro (Università degli Studi di Perugia)

Edoardo Mosconi (Università degli Studi di Perugia)

Filippo De Angelis (Università degli Studi di Perugia)

Samuel D. Stranks (University of Cambridge)

Andreas Baumann (Das Bayerische Zentrum fur Angewandte Energieforschung e.V.)

Vladimir Dyakonov (University of Würzburg)

Eline M. Hutter (Center for Nanophotonics, TU Delft - ChemE/Opto-electronic Materials)

Tom J. Savenije (AMOLF Institute for Atomic and Molecular Physics, TU Delft - ChemE/Opto-electronic Materials)

Research Group
ChemE/Opto-electronic Materials
DOI related publication
https://doi.org/10.1021/acs.jpclett.9b02160
More Info
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Publication Year
2019
Language
English
Research Group
ChemE/Opto-electronic Materials
Issue number
17
Volume number
10
Pages (from-to)
5128-5134
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Abstract

Recently, several studies have investigated dielectric properties as a possible origin of the exceptional optoelectronic properties of metal halide perovskites (MHPs). In this study we investigated the temperature-dependent dielectric behavior of different MHP films at different frequencies. In the gigahertz regime, dielectric losses in methylammonium-based samples are dominated by the rotational dynamics of the organic cation. Upon increasing the temperature from 160 to 300 K, the rotational relaxation time, τ, decreases from 400 (200) to 6 (1) ps for MAPb-I3 (-Br3). By contrast, we found negligible temperature-dependent variations in τ for a mixed cation/mixed halide FA0.85MA0.15Pb(I0.85Br0.15)3. From temperature-dependent time-resolved microwave conductance measurements we conclude that the dipolar reorientation of the MA cation does not affect charge carrier mobility and lifetime in MHPs. Therefore, charge carriers do not feel the relatively slow-moving MA cations, despite their great impact on the dielectric constants.