In-plane anisotropic faceting of ultralarge and thin single-crystalline colloidal SnS nanosheets

TL;DR

This paper reports a novel colloidal synthesis method for large, thin, single-crystalline SnS nanosheets with tunable in-plane anisotropic faceting, enabling control over growth directions and revealing anisotropic electronic transport properties.

Contribution

It introduces the first solution-phase synthesis of large thin SnS nanosheets with controllable edge faceting and anisotropic growth directions.

Findings

Successful synthesis of large, thin SnS nanosheets with tunable faceting.

Growth direction can be switched by ligand adjustment.

Electronic transport is direction-dependent, confirming structural anisotropy.

Abstract

The colloidal synthesis of large thin two-dimensional (2D) nanosheets is fascinating but challenging, since the growth along the lateral and vertical dimensions need to be controlled independently. In-plane anisotropy in 2D nanosheets is attracting more attention as well. We present a new synthesis for large colloidal single-crystalline SnS nanosheets with the thicknesses down to 7 nm and lateral sizes up to 8 um. The synthesis uses trioctylphosphine-S (TOP-S) as sulfur source and oleic acid (with or without TOP) as ligands. Upon adjusting the capping ligand amount, the growth direction can be switched between anisotropic directions (armchair and zigzag) and isotropic directions ("ladder" directions), 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.