Hot-Injection Synthesis of Monodisperse π-SnS Nanocrystals

Tin chalcogenide nanocrystals (NCs), particularly tin(II) sulfide (SnS), hold promise for environmentally benign optoelectronic applications. However, challenges such as scalable synthesis, susceptibility to oxidation, and unclear reaction mechanisms hinder further research and limit the exploration of their electronic properties. This study presents a single ligand-controlled hot-injection strategy to synthesize monodisperse π-SnS NCs (4.7–8.5 nm) with unprecedented size uniformity and long-term stability (>1 year). By systematically optimizing precursor mole ratios (Sn/S up to 4:1) and adjusting solvent composition (reducing 1-octadecene (ODE) volume to ≤1.84 mL), we achieved narrow size distributions (standard deviation of 0.4–0.7 nm) and suppressed phase impurities, overcoming the limitations of conventional hot-injection methods that rely on multiple ligands. The synthesis advances demonstrated optoelectronic properties: size-dependent quantum confinement (band gap tuning via NC diameter) and p-type behavior in NC thin films treated with ligand 1,2-ethanedithiol (EDT). These findings provide a scalable, single-ligand synthesis framework for π-SnS NCs, resolving challenges in reproducibility and stability while opening pathways for eco-friendly NC-based electronics.