Ambipolar Seebeck Coefficient in MoS2/MoS2–MoO2 Graded Composites by Junction Reciprocation

We fabricated radially transformed growth of MoS₂ to MoS₂–MoO₂ by the two-zone chemical vapor transport (CVT) technique. The idea to apply heat, i.e., hot junction (T_H), on both the edges of the film has a distinct ambipolar Seebeck coefficient (S) of −20 μVK^–1 with MoS₂ as hot junction, and 69.5 μVK^–1 with MoS₂–MoO₂ as hot junction. The positive S at MoS₂–MoO₂ indicates fast hole injection at a lower degree of interface Fermi-level pinning and large asymmetry at the junctions through low energy carrier scattering in the multiple potential barriers at the interfaces of each region. The decreased Θ_D around 5 K than MoS₂ reveals the lattice softening due to reduced strength of chemical bonding at MoS₂–MoO₂. The report propounds the potential utilization of multiple potential barriers for thin film graded composites in thermoelectric applications.