Abnormal Thickness‐Dependent Thermal Transport in Suspended 2D PdSe₂

Abstract

Research on 2D materials originally focused on the highly symmetrical materials like graphene, h‐BN. Recently, 2D materials with low‐symmetry lattice such as PdSe2 have drawn extensive attention, due to the interesting layer‐dependent bandgap, promising mechanical properties and excellent thermoelectric performance, etc. In this work, the phonon thermal transport is studied in PdSe2 with a pentagonal fold structure. The thermal conductivity of PdSe2 flakes with different thicknesses ranging from few nanometers to several tens of nanometers is measured through the thermal bridge method, where the thermal conductivity increases from 5.04 W mk−1 for 60 nm PdSe2 to 34.51 W mk−1 for the few‐layer one. The atomistic modelings uncover that with the thickness thinning down, the lattice of PdSe2 becomes contracted and the phonon group velocity is enhanced, leading to the abnormal increase in the thermal conductivity. And the upshift of the optical phonon modes contributes to the increase of the thermal conductivity as well by creating less acoustic phonon scattering as the thickness reduces. This study probes the interesting abnormal thickness‐dependent thermal transport in 2D materials, which promotes the potential thermal management at nanoscale.

Modulating Carrier Dynamics in PdSe2: The Role of Pressure in Electronic and Phononic Interactions

“…The phonon spectra of the orthorhombic phase show the gap closing at around 4 THz upon 3 GPa. Additionally, low-frequency phonons gradually harden to 2 THz, while phonons at 8 THz soften and stabilize at around 6 THz, which may enhance the efficiency of four-phonon scattering. , These provide a more efficient pathway for phonon–phonon scattering. Therefore, although the electronic bandgap closes after 3 GPa, the rate of interband recombination continues to increase.…”