Abstract
In this paper, we investigated the anisotropic thermal transport in two-dimensional (2D) perovskite (phenethylammonium lead iodide) nanolayers through a measurement technique called cross-sectional scanning thermal microscopy. In this method, a target perovskite layer on a substrate was oblique polished with an Ar ion beam to create a low-angle wedge with nanoscale roughness that is followed by high-vacuum scanning thermal microscopy to obtain the thermal conductance map as a function of local thickness. The experimentally obtained data were processed with an analytical model and validated by the finite elemental analysis simulation to quantify the in-plane and cross-plane thermal conductivities of the 2D perovskite from a single set of measurements with nanoscale resolution. We obtained ultralow thermal conductivity for the 2D perovskite along with an anisotropy linked to the unique structure of the perovskite and different phonon lifetimes and group velocities for in-plane and out-of-plane directions. The results that are available are essential for the thermal management of 2D perovskite-based optoelectronic devices and potential thermoelectric applications of these materials.
- Received 24 April 2022
- Revised 17 December 2022
- Accepted 20 December 2022
DOI:https://doi.org/10.1103/PhysRevMaterials.7.023801
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