Temperature-driven thermoelectric transition in orthorhombic-ZrS ₂ monolayer via first-principles analysis

Two-dimensional (2D) materials hold immense promise for a wide range of applications due to their exceptional and tunable properties. Among these, transition metal compounds stand out for their compositional versatility, enabling precise control of their physical and chemical characteristics. In this study, we systematically investigate the structural, electronic and optoelectronic properties of orthorhombic ZrS 2 (o-ZrS 2 ), with a focus on the influence of atomic positioning within its lattice. Phonon dispersion analysis confirms the dynamic stability of the structure, while mechanical stability is established through energy–strain relationships derived from elastic constants. Electronic band structure and density of states (DOS) analyses identify o-ZrS 2 as a semiconductor with band gaps of 0.715[Formula: see text]eV and 1.847[Formula: see text]eV calculated using PBE and HSE06 methods, respectively, primarily attributed to the overlap of Zr–d and S–p orbitals. Optical absorption spectra demonstrate strong UV light absorption, peaking at 11.8[Formula: see text]eV with an absorption coefficient of [Formula: see text] [Formula: see text]cm[Formula: see text]. Furthermore, thermoelectric analysis reveals a high electronic figure of merit (ZT[Formula: see text] ranging from 1.022 to 1.073 and high-power factor (PF) of [Formula: see text]–[Formula: see text] over the temperature range of 300–900[Formula: see text]K. These results underscore the potential of o–ZrS 2 as a high-bandgap semiconductor with excellent UV absorption and thermoelectric performance (ZT[Formula: see text]), making it a promising candidate for next-generation thermoelectric devices.