![]() Thermoelectric properties of TMDCs, especially, have been investigated because of diverse electronic properties, low thermal conductivity, and moderate Seebeck coefficient. In particular, semiconducting compounds, such as MX 2 (M = Mo, W, or Re X = S or Se), have been intensively investigated for their novel electronic and optical properties such as direct–indirect band gap transition, large exciton signal, valley polarization, anisotropic electronic properties, and thermoelectric properties. Such weak van der Waals bonding allows exfoliation of individual layers, stacking of arbitrary heterostructures, intercalation of charged ions (Li + or Na +), and low thermal conductivity in the vertical direction. The hexagonal metal layer is sandwiched by two hexagonal chalcogen layers, while the interface between the chalcogen layers is weakly bonded through van der Waals bonding. They comprise one transition metal atom (i.e., Mo or W) and two chalcogen atoms (i.e., S, Se, or Te). Transition metal dichalcogenides (TMDCs) have attracted considerable attention as two-dimensional (2D) material candidates beyond graphene owing to their unique electronic, optical, mechanical, chemical, and thermal properties. These results suggest that helium ion irradiation is a promising method to significantly improve the thermoelectric properties of two-dimensional transition metal dichalcogenides. Raman spectroscopy, X-ray diffraction, and transmission electron microscopy analyses revealed that irradiation-induced selenium vacancies played an important role in changing the thermoelectric properties of MoSe 2 thin films. At the optimal irradiation dose of 10 15 cm −2, we observed multiple enhancements of the power factor resulting from an increase in the electrical conductivity, with slight suppression of the Seebeck coefficient. In this study, we investigated the effect of helium ion irradiation on MoSe 2 thin films with the objective of controlling the Seebeck coefficient and electrical conductivity. Therefore, it is necessary to find a way to adjust one of these parameters without affecting the other parameters. However, their thermoelectric parameters such as Seebeck coefficient, electrical conductivity, and thermal conductivity are interdependent, which is a drawback. Transition metal dichalcogenides have attracted renewed interest for use as thermoelectric materials owing to their tunable bandgap, moderate Seebeck coefficient, and low thermal conductivity. ![]()
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