Quantifying anisotropic thermal transport in two-dimensional perovskite <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:msub><mml:mi>PEA</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>PbI</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:math> through cross-sectional scanning thermal microscopy

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 microscopy. method, target layer on substrate was oblique polished with an Ar ion beam to create low-angle wedge nanoscale roughness that is followed by high-vacuum microscopy obtain conductance map as function of local thickness. The experimentally obtained data were processed analytical model and validated finite elemental analysis simulation quantify in-plane $({k}_{l,xy})$ cross-plane conductivities $({k}_{l,z})$ 2D from single set measurements resolution. We ultralow conductivity $({k}_{l}=0.25\ifmmode\pm\else\textpm\fi{}0.05\phantom{\rule{0.16em}{0ex}}\mathrm{W}\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1})$ for along anisotropy $({k}_{l,\phantom{\rule{0.16em}{0ex}}xy}=0.45\ifmmode\pm\else\textpm\fi{}0.05\phantom{\rule{0.16em}{0ex}}\mathrm{W}\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}\mathrm{and}\phantom{\rule{0.16em}{0ex}}{k}_{l,\phantom{\rule{0.16em}{0ex}}z}=0.13\ifmmode\pm\else\textpm\fi{}0.05\phantom{\rule{0.16em}{0ex}}\mathrm{W}\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1})$ linked unique structure different phonon lifetimes group velocities out-of-plane directions. results are available essential management perovskite-based optoelectronic devices potential thermoelectric applications these materials.