Achieving type-II SnSSe/as van der waals heterostructure with satisfactory oxygen tolerance for optoelectronic and photovoltaic applications

Construction of van der Waals heterostructure provides a straightforward way to blend properties of different monolayer materials for enhanced photovoltaic performance. Herein, motivated by the successful characterization of monolayer SnX₂ (X ​= ​S, Se) and arsenene (As), detailed interfacial interaction and optical absorption proficiencies of novel SnSSe/As heterostructure have been systematically investigated. Findings reveal that the SnSSe/As heterostructure exhibits a type-II band arrangement with an indirect bandgap of 1.30 ​eV that approaches the desirable Shockley-Queisser Limit under 2% biaxial tensile strain, strong absorption of 10⁴-10⁵ ​cm⁻¹ toward solar irradiation that encompasses the infrared-ultraviolet region and high carrier mobility up to 910.71 ​cm² ​V⁻¹ ​s⁻¹. Large, negative binding energy and absence of chemical bonds at the heterostructure interface imply its stability. The dynamical and mechanical stabilities have also been confirmed. Moreover, analysis of oxygen adsorption suggests tolerable performance deterioration with SnSSe side facing the ambient air. Hence, a photovoltaic with power conversion efficiency (PCE) exceeding 30% is ultimately proposed.