Electronic, thermoelectric and optical properties of MoTe2 and M2CO2 (M= Ti, Zr and Hf) monolayers and their van der Waals heterostructures

Abstract

Two-dimensional (2D) materials are characterized by their unique structure, where layers are connected by weak van der Waals (vdW) interactions between neighboring atoms. The main advantages of these 2D materials lie in van der Waals heterostructures (vdWHs), which exhibit unique and combined functionalities of the parent monolayers and play crucial roles in numerous fields. In this work, we used density functional theory calculations and investigated the undefined properties of the MoTe₂ and M₂CO₂ (M = Ti, Zr and Hf) monolayers and their vdWHs. We calculated the optoelectronic properties of the MoTe₂ and M₂CO₂ (M = Ti, Zr and Hf) monolayers. The calculated electronic band structure confirmed that MoTe₂ has a direct band, while M₂CO₂ monolayers have indirect band nature. We further investigated the optical and thermoelectric properties of the MoTe₂ and M₂CO₂ (M = Ti, Zr and Hf) monolayers. Furthermore, we demonstrated the structural and optoelectronic properties of M₂CO₂–MoTe₂ (M = Ti, Zr and Hf) vdWHs. Our calculated band structures show that Ti₂CO₂–MoTe₂ and Zr₂CO₂– MoTe₂ have indirect bands, while interestingly, Hf₂CO₂– MoTe₂ shows direct bands, with type-II band alignment. Optical properties indicated that M₂CO₂– MoTe₂ vdWHs have the ability to absorb a broad range of light, from the ultraviolet to the visible and infrared regions. Finally, we also calculated the thermoelectric properties of these systems, which suggested that these vdWHs could play a crucial role in enhancing the thermoelectric performance.