Two-dimensional
materials such as graphene and transition metal
dichalcogenides (TMDCs) have received extensive research interest
and investigations in the past decade. In this research, we used a
refined opto-thermal Raman technique to explore the thermal transport
properties of one popular TMDC material WSe2, in the single-layer
(1L), bilayer (2L), and trilayer (3L) forms. This measurement technique
is direct without additional processing to the material, and the absorption
coefficient of WSe2 is discovered during the measurement
process to further increase this technique’s precision. By
comparing the sample’s Raman spectroscopy spectra through two
different laser spot sizes, we are able to obtain two parameterslateral
thermal conductivities of 1L–3L WSe2 and the interfacial
thermal conductance between 1L–3L WSe2 and the substrate.
We also implemented full-atom nonequilibrium molecular dynamics simulations
(NEMD) to computationally investigate the thermal conductivities of
1L–3L WSe2 to provide comprehensive evidence and
confirm the experimental results. The trend of the layer-dependent
lateral thermal conductivities and interfacial thermal conductance
of 1L–3L WSe2 is discovered. The room-temperature
thermal conductivities for 1L–3L WSe2 are 37 ±
12, 24 ± 12, and 20 ± 6 W/(m·K), respectively. The
suspended 1L WSe2 possesses a thermal conductivity of 49
± 14 W/(m·K). Crucially, the interfacial thermal conductance
values between 1L–3L WSe2 and the substrate are
found to be 2.95 ± 0.46, 3.45 ± 0.50, and 3.46 ± 0.45
MW/(m2·K), respectively, with a flattened trend starting
the 2L, a finding that provides the key information for thermal management
and thermoelectric designs.