First-principles studies on the structural, electronic, and optical properties of 2D transition metal dichalcogenide (TMDC) and Janus TMDCs heterobilayers.

Van der Waals (vdW) heterobilayers formed by vertically stacked twodimensional materials could be a viable candidate for optoelectronics. This study carried out frst-principles calculations to study the geometrical, electronic and optical properties of heterobilayers consisting transition metal dichalcogenide (TMDC) SnSe2 and Janus TMDCs ZrSSe and SnSSe. Eight possible confgurations SeSnSe-SSnSe (I), SeSnSe-SeSnS (II), SeSnSe-SZrSe (III), SeSnSe-SeZrS (IV), SSnSe-SZrSe (V), SSnSeSeZrS (VI), SeSnS-SZrSe (VII) and SeSnS-SeZrS (VIII) are dynamically, thermally, energetically and mechanical stable. Six confgurations, (I, II, III, IV, V and VI) have indirect band gaps with type-II band alignments, enhancing carrier lifetime an essential feature for potential applications in photovoltaic and nanoelectronics devices. In contrast, VII and VIII have indirect band gap with a type-I band alignment, facilitating
effcient recombination of electron-hole pairs under high irradiation. All heterobilayers demonstrated signifcant optical absorption in the visible region. These fndings highlight the potential utilization of heterobilayers in electronic and optoelectronic devices.