Abnormal Seebeck Effect in Vertically Stacked 2D/2D PtSe₂ /PtSe₂ Homostructure

When a thermoelectric (TE) material is deposited with a secondary TE material, the total Seebeck coefficient of the stacked layer is generally represented by a parallel conductor model. Accordingly, when TE material layers of the same thickness are stacked vertically, the total Seebeck coefficient in the transverse direction may change in a single layer. Here, an abnormal Seebeck effect in a stacked two-dimensional (2D) PtSe₂ /PtSe₂ homostructure film, i.e., an extra in-plane Seebeck voltage is produced by wet-transfer stacking at the interface between the PtSe₂ layers under a transverse temperature gradient is reported. This abnormal Seebeck effect is referred to as the interfacial Seebeck effect in stacked PtSe₂ /PtSe₂ homostructures. This effect is attributed to the carrier-interface interaction, and has independent characteristics in relation to carrier concentration. It is confirmed that the in-plane Seebeck coefficient increases as the number of stacked PtSe₂ layers increase and observed a high Seebeck coefficient exceeding ≈188 µV K^-1 at 300 K in a four-layer-stacked PtSe₂ /PtSe₂ homostructure.