Temperature-Dependent Thermal Transport of Polycrystalline van der Waals Semimetallic PtSe2 Films

We report both phononic and electronic transports ofpolycrystallinelarge-area platinum diselenide (PtSe2) thin films by measuringin-plane thermal conductivity and the Seebeck coefficient using asuspended bridge-type method and a strain gauge-controlled suspendplatform, respectively. We observe the greatly suppressed in-planethermal conductivity of & SIM;2.6 W/m & BULL;K, which is approximately670% suppressed value, for 11 nm thick polycrystalline PtSe2 films as compared to that of an exfoliated similarly thick in-planesingle-crystalline PtSe2 layer at 300 K. This reductionis attributed to the enhanced phonon scattering in polycrystallinePtSe(2) thin films. The measured in-plane Seebeck coefficientand electrical conductivity of the samples are as high as & SIM;79 & mu;V/K and & SIM;416 S/cm at 300 K, respectively. Our findingscan pave the way toward an effective strategy for promising large-areaTE energy harvesting devices with a high figure-of-merit in 2D semimetallictransition-metal dichalcogenide materials.