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

Published version
Peer-reviewed

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Authors

Caselli, Valentina M 
Fischer, Mathias 
Meggiolaro, Daniele  ORCID logo  https://orcid.org/0000-0001-9717-133X
Mosconi, Edoardo 
De Angelis, Filippo  ORCID logo  https://orcid.org/0000-0003-3833-1975

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.

Description

Keywords

3403 Macromolecular and Materials Chemistry, 34 Chemical Sciences, 3406 Physical Chemistry

Journal Title

J Phys Chem Lett

Conference Name

Journal ISSN

1948-7185
1948-7185

Volume Title

10

Publisher

American Chemical Society (ACS)
Sponsorship
Royal Society (UF150033)