High-efficiency (21%) SnS heterojunction solar cells enabled by a novel ZrS₂ buffer layer: a numerical study

• Novel ZrS₂/SnS solar cell achieves a simulated efficiency of 21.0%. • Optimized with a 0.05 µm ZrS₂ buffer and a 2.0 µm SnS absorber layer. • Achieves a high open-circuit voltage (Voc) of 0.860 V. • Delivers a strong short-circuit current density (Jsc) of 34.2 mA/cm². Zirconium disulfide (ZrS 2 ), a transition metal dichalcogenide (TMDC), is a promising candidate for photovoltaic applications. This study presents a numerical analysis of a novel inorganic ZrS 2 /SnS heterojunction solar cell structure using the Solar Cell Capacitance Simulator in one dimension (SCAPS-1D) software. Our simulations demonstrate that key performance parameters-including charge carrier collection length, minority carrier lifetime, photogenerated current density, and recombination rate-significantly influence device efficiency. An optimized simulated device achieved a power conversion efficiency (PCE) of 21.0%, with an open-circuit voltage (V oc ) of 0.860 V, a short-circuit current density (J sc ) of 34.2 mA/cm², and a fill factor (FF) of 70.0%. This efficiency was obtained with an SnS absorber layer (band gap = 1.3 eV, thickness = 2.0 µm, acceptor concentration > 10¹⁶ cm⁻³) and a ZrS₂ buffer layer (band gap = 1.7 eV, thickness = 0.05 µm, donor concentration < 10¹⁹ cm⁻³). These results indicate that the ZrS₂/SnS heterojunction is a highly promising structure for fabricating efficient, low-cost, and scalable thin-film photovoltaic devices.