In-Plane Anisotropic Faceting of Ultralarge and Thin Single-Crystalline Colloidal SnS Nanosheets.

The colloidal synthesis of large and thin two-dimensional (2D) nanosheets is fascinating but challenging, since the growth along the lateral dimension and vertical dimensions need to be controlled independently. In-plane anisotropy in 2D nanosheets is attracting more attention as well. We present a new improved synthesis for large colloidal single-crystalline SnS nanosheets with the thicknesses down to 7 nm and lateral sizes up to 8 µm. The synthesis uses trioctylphosphine-S as sulfur source and oleic acid as ligands. Upon adjusting the amount of capping ligands, the growth direction can be switched between anisotropic directions (armchair and zigzag) and isotropic directions ("ladder" direction), leading to an edge-morphology anisotropy. This is the first report on solution-phase synthesis of large thin SnS NSs with tunable edge faceting. Furthermore, electronic transport measurements show strong dependency on the crystallographic directions confirming structural anisotropy.