Composition-Dependent Wide-Range Tunability of Optical and Electronic Properties in SnS_xSe_(2-x) Alloy Nanosheets

Isovalent alloying in printable metal dichalcogenide nanomaterials enables precise, application-targeted property tuning. However, a scalable platform offering broad optical and electrical tunability has so far remained elusive. Herein, we establish a powder-based, solution-processed route to access the full domain of SnS_xSe_(2-x) alloy nanosheets, providing control over a wide range of properties through chalcogenide composition. The n-type nanosheet alloy series shows a wide spread in optical and in-plane electrical properties, ranging from 1.67 eV and low bandgap metallic-like behavior for 2D SnSe₂, to 2.46 eV and wide bandgap semiconducting behavior with high-resistivity for 2D SnS₂. The out-of-plane conductivity is also tunable, showing nonmonotonic behavior with an optimal chalcogenide ratio of x = 1.2 - 1.6. Using photoelectrochemistry as an example, we highlight how the interplay of these tunable properties enables optimized performance for targeted applications. The exceptional range of tailorable properties reported here provides a roadmap for tuning these alloys, thereby opening avenues for their potential application in a multitude of fields.