Thermoelectric properties of a series of polycrystalline Mo(Se _{1− x} Te _x ) ₂

Abstract 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 MoSe ₂ –MoTe ₂ system are investigated. A series of Mo(Se _{1− x} Te _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 MoSe ₂ and MoTe ₂ . 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 MoTe ₂ sample exhibited the maximum power factor of .014 mW/(m K ² ) at 823 K. The lattice thermal conductivities of the alloyed samples ( x = .25, .5, and .75) significantly decreased compared to MoSe ₂ and MoTe ₂ 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 MoTe ₂ 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 _0.25 Te _0.75 ) ₂ sample.