Excellent thermoelectric performance induced by interface effect in MoS₂/MoSe₂ van der Waals heterostructure

Herein, thermoelectric properties of MoS₂/MoSe₂ lateral and van der Waals heterostructure are investigated by using density functional theory calculations and non-equilibrium Green's function method. Compared with pure MoS₂, the thermoelectric performance of MoS₂/MoSe₂ lateral heterostructure is significantly improved due to the sharply decreased thermal conductance and slightly reduced power factor. Moreover, the thermoelectric performance can be further improved by constructing MoS₂/MoSe₂ van der Waals heterostructure. The room temperature ZT can reach 3.5, which is about 3 and 6 times greater than MoS₂/MoSe₂ lateral heterostructure and pure MoS₂, respectively. This is because the strongly local electron and phonon states result in an ultralow thermal conductance in MoS₂/MoSe₂ van der Waals heterostructure. Furthermore, we also find that the thermoelectric performance of MoS₂/MoSe₂ van der Waals heterostructure is insensitive to contact areas due to the competing influence of PF and total thermal conductance. The current study presents an effective strategy to improve the thermoelectric performance of 2D heterostructures, which can be extended to a variety of materials for different applications.