Effect of dimensionality on thermoelectric powerfactor of molybdenum disulfide

We present that two-dimensional (2D) bilayer molybdenum disulfide (MoS2) exhibits an enhanced Seebeck coefficient over its three-dimensional (3D) counterpart arising from dimensionality confinement. It has been predicted that quantum confinement enhances thermoelectric performance but no studies have focused on a single material to present a theoretical and experimental comparison, which would illustrate the enhancement of thermoelectric performance. Layered MoS2 provides an opportunity to verify this hypothesis and in this work, we extensively study the Seebeck coefficient, S, the electrical conductivity, σ, and the thermoelectric powerfactor, S2σ of 2D monolayer and bilayer MoS2 using theoretical Boltzmann Transport Equation calculations and compare the results to well-characterized experimental data. We conclude that dimensional confinement indeed enhances the Seebeck coefficient by up to ∼50% in 2D bilayer MoS2 over 3D MoS2 under similar doping concentrations because of the discretization of density of states. We also consider electrical conductivity with various energy-dependent scattering rates considering charged-impurities and acoustic phonon mediated scattering, and comment on a theoretical comparison of the powerfactor to the best-case scenario for 3D MoS2.