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Ultralow Thermal Conductivity of Two-Dimensional Metal Halide Perovskites
journal contribution
posted on 2020-03-31, 13:08 authored by Ashutosh Giri, Alexander Z. Chen, Alessandro Mattoni, Kiumars Aryana, Depei Zhang, Xiao Hu, Seung-Hun Lee, Joshua J. Choi, Patrick E. HopkinsWe
report on the thermal conductivities of two-dimensional metal
halide perovskite films measured by time domain thermoreflectance.
Depending on the molecular substructure of ammonium cations and owing
to the weaker interactions in the layered structures, the thermal
conductivities of our two-dimensional hybrid perovskites range from
0.10 to 0.19 W m–1 K–1, which
is drastically lower than that of their three-dimensional counterparts.
We use molecular dynamics simulations to show that the organic component
induces a reduction of the stiffness and sound velocities along with
giving rise to vibrational modes in the 5–15 THz range that
are absent in the three-dimensional counterparts. By systematically
studying eight different two-dimensional hybrid perovskites, we show
that the thermal conductivities of our hybrid films do not depend
on the thicknesses of the organic layers and instead are highly dependent
on the relative orientation of the organic chains sandwiched between
the inorganic constituents.