TY - JOUR
T1 - Charge Carriers Are Not Affected by the Relatively Slow-Rotating Methylammonium Cations in Lead Halide Perovskite Thin Films
AU - Caselli, Valentina M.
AU - Fischer, Mathias
AU - Meggiolaro, Daniele
AU - Mosconi, Edoardo
AU - De Angelis, Filippo
AU - Stranks, Samuel D.
AU - Baumann, Andreas
AU - Dyakonov, Vladimir
AU - Hutter, Eline M.
AU - Savenije, Tom J.
PY - 2019/9/5
Y1 - 2019/9/5
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85072068438&partnerID=8YFLogxK
U2 - 10.1021/acs.jpclett.9b02160
DO - 10.1021/acs.jpclett.9b02160
M3 - Article
C2 - 31398042
AN - SCOPUS:85072068438
SN - 1948-7185
VL - 10
SP - 5128
EP - 5134
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 17
ER -