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

Abstract Van der Waals heterobilayers formed by vertically stacked two-dimensional materials could be a viable candidate for optoelectronics. This study carried out first-principles calculations to study the geometrical, electronic and optical properties of heterobilayers consisting transition metal dichalcogenide (TMDC) SnSe 2 and Janus TMDCs ZrSSe and SnSSe. Eight possible configurations SeSnSe–SSnSe (I), SeSnSe–SeSnS (II), SeSnSe–SZrSe (III), SeSnSe–SeZrS (IV), SSnSe–SZrSe (V), SSnSe–SeZrS (VI), SeSnS–SZrSe (VII) and SeSnS–SeZrS (VIII) are dynamically, thermally, energetically and mechanical stable. Six configurations, (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 efficient recombination of electron–hole pairs under high irradiation. All heterobilayers demonstrated significant optical absorption in the visible region. These findings highlight the potential utilization of heterobilayers in electronic and optoelectronic devices.