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

Journal article (2019)

Authors

V.M. Caselli ChemE/Opto-electronic Materials - AS
Mathias Fischer University of Würzburg
Daniele Meggiolaro University of Perugia
Edoardo Mosconi University of Perugia
Filippo De Angelis University of Perugia
Samuel D. Stranks University of Cambridge
Andreas Baumann Das Bayerische Zentrum fur Angewandte Energieforschung e.V.
Vladimir Dyakonov University of Würzburg
E.M. Hutter ChemE/Opto-electronic Materials - AS , Center for Nanophotonics
T.J. Savenije AMOLF, ChemE/Opto-electronic Materials - AS
Research Group
ChemE/Opto-electronic Materials (AS) (TU Delft)
Copyright: © 2019 V.M. Caselli, Mathias Fischer, Daniele Meggiolaro, Edoardo Mosconi, Filippo De Angelis, Samuel D. Stranks, Andreas Baumann, Vladimir Dyakonov, E.M. Hutter, T.J. Savenije
DOI: https://doi.org/10.1021/acs.jpclett.9b02160
More Info
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Published Date

2019

Language

English

Faculty

Applied Sciences

Department

ChemE/Chemical Engineering

Research Group

ChemE/Opto-electronic Materials

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.