Thermoelectric properties of a series of polycrystalline Mo(Se_1−xTe_x)₂

Transition metal dichalcogenides have being actively studied on the account of their large density-of-state effective mass and low lattice thermal conductivity. Herein, thermoelectric and electrical transport properties of MoSe₂–MoTe₂ system are investigated. A series of Mo(Se_1−xTe_x)₂ (x = 0,.25,.5,.75, and 1) polycrystalline samples was synthesized by conventional solid-state reaction. Single hexagonal phase was identified for each sample without secondary phase, confirming the formation of complete solid solutions between MoSe₂ and MoTe₂. The electrical conductivity and magnitude of the Seebeck coefficient increased simultaneously with increasing Te content x at high temperatures, with the power factor following the same trend. As results, the MoTe₂ sample exhibited the maximum power factor of.014 mW/(m K²) at 823 K. The lattice thermal conductivities of the alloyed samples (x =.25,.5, and.75) significantly decreased compared to MoSe₂ and MoTe₂ owing to point defect phonon scattering via anion substitution, which is verified by the Debye–Callaway model. A maximum zT of.0044 was obtained for MoTe₂ sample at 773 K; however, the calculated quality factor B values of the samples with x =.75 and 1 at 773 K were almost identical, suggesting that a further enhancement of zT can be achieved by optimizing an n_H of the Mo(Se_0.25Te_0.75)₂ sample.