Transport properties of few-layer NbSe2: From electronic structure to thermoelectric properties

Phonon Dominated Thermal Transport in Metallic Niobium Diselenide from First Principles Calculations

“…A large z-direction vacuum space of 20 Å is left in the simulation box to prevent interactions between the layer and its periodic images in the cross-plane direction to simulate this monolayer. Our first principles optimized lattice parameters are calculated to be a = b = 3.474 Å, and it agrees well with the experimental values a = b = 3.445 Å [ 30 ]. The simulation is conducted on CPU, while the rapid evolution of DFT calculation on GPU may enable a much larger scale simulation, which is important for the thermoelectric device design.…”

“…Another challenge in experimentally determining the thermal transport properties in the few layer or monolayer NbSe 2 is the tendency for oxidation under ambient environment [ 29 ], making high quality samples rare and the existing experimental results ambiguous. For example, recent thermoelectric properties studies of bulk NbSe 2 showed across-plane thermal conductivity of 2.1 W/mK, and a recent study of transport properties of 4-layer NbSe 2 in the low temperature range reported an in-plane thermal conductivity of 32 ± 10 W/mK at 200 K using a heat diffusion imaging method [ 30 ]. It also shows that the thermal conductivity can rise to a maximum of 53 ± 11 W/mK at 120 K, and then decrease as temperature increases.…”

Electrostatic modulation of thermoelectric transport properties of 2H-MoTe2

“…Electrical pulses (5 V, 5 ms) were sent to the heater. The heat spreader principles have been demonstrated on systems down to a few-layer, 36,37 which warrants the application of the heat diffusion imaging method to our samples of tens of nm in thickness. The sensitivity of the data is determined by the ratio of the in-plane thermal conductance of the sample to the cross-plane thermal conductance of the substrate.…”

Revealing large room-temperature Nernst coefficients in 2D materials by first-principles modeling

“…The Nernst effect hasn't received as much attention as the Seebeck effect and literature on the ordinary Nernst effect in 2D materials is considerably scarce ( e.g. , 1T-TaS 2 , 44 quasi-two-dimensional CsCa 2 Fe 4 As 4 F 2 , 45 NbSe 2 , 46 graphene, 47–49 and Mo 1− x W x Te 2 50 ), particularly at higher temperatures.…”