Enhanced Transverse Seebeck Coefficients in 2D/2D PtSe2/MoS2 Heterostructures Using Wet-Transfer Stacking

It is very challenging to estimate thermoelectric (TE) properties when applying millimeter-scale two-dimensional (2D) transition metal dichalcogenide (TMDC) materials to TE device applications, particularly their Seebeck coefficient due to their high intrinsic electrical resistance. This paper proposes an innovative approach to measure large transverse (i.e., in-plane) Seebeck coefficients for 2D TMDC materials by placing a low resistance (LR) semimetallic PtSe2 film on high-resistance (HR) semiconducting MoS2 (>10 MΩ), whose internal resistance is too high to measure the Seebeck coefficient, forming a heterojunction structure using wet-transfer stacking. The vertically stacked LR-PtSe2 (3 nm)/HR-MoS2 (12 nm) heterostructure film exhibits a high Seebeck coefficient > 190 μV/K up to 5 K temperature difference. This unusual behavior can be explained by an additional Seebeck effect induced at the interface between the LR-2D/HR-2D heterostructure. The proposed stacked LR-PtSe2/HR-MoS2 heterostructure film offers promising phenomena 2D/2D materials that enable innovative TE device applications.