Unconventional Thermal Rectification in Assemblies of Supertetrahedral T<sub>3</sub>-Type Sn<sub>4</sub>In<sub>6</sub>Se<sub>20</sub> Clusters.

Du, Peng-Hu; Kawazoe, Yoshiyuki; Sun, Qiang · Nano Lett · 2024

basic_science · Level V

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Abstract

Going beyond the conventional design paradigm with atoms as building blocks, we propose the concept of cluster-assembled thermal rectifiers comprising metal chalcogenide supertetrahedral clusters. Different from the experimentally reported T<sub>4,∞</sub> and T<sub>5,∞</sub>, for the first time we assemble T<sub>3</sub>-Sn<sub>4</sub>In<sub>6</sub>Se<sub>20</sub> clusters into a stable T<sub>3,∞</sub> framework without needing extra ions, based on which the thermal rectification (TR) effect is explored using machine-learning molecular dynamics and the mode-resolved phonon Boltzmann transport equation. The tetrahedron-shaped cluster assembly serves as a novel TR switch, where the open state shows an outstanding TR efficiency (∼40%) arising from the asymmetric lateral confinement due to not only the phonon particle behavior but also the phonon wave nature. The prism-shaped assembly has a symmetric skeleton but with asymmetric surface roughness induced by clusters, thus exhibiting an unusual TR effect, distinguished from atom-based symmetric systems with atomically flat surfaces. Our findings demonstrate the unique potential of cluster assemblies for unconventional thermal rectification.