Shape-Controlled Synthesis of SnE (E = S, Se) Semiconductor Nanocrystals for Optoelectronics

We report new methods of synthesizing colloidal SnE (E = S, Se) nanocrystals (NCs) with morphologies including quantum dots (QDs), nanoplates, single-crystalline nanosheets, nanoflowers, and nanopolyhedra. Both the selection of chalcogenide precursors and the combination of ligands play essential roles in determining the morphology of the SnS and SnSe NCs. In contrast with previous methods for synthesis of tin chalcogenide NCs, which generally used a relatively expensive and flammable organic tin precursor, bis[bis(trimethylsilyl)amino]tin(II), we employ inexpensive SnCl2 and identify chalcogenide precursors with appropriate reactivity to enable production of nearly monodisperse SnSe NCs and SnS nanostructures. A metal-semiconductor metal (MSM) device was fabricated to study the optoelectronic properties of SnSe NC thin films, spin-cast from colloidal SnSe NC dispersions. The photoresponse of the SnSe thin film to AM 1.5 simulated solar illumination demonstrates the potential of SnSe NCs for use in optoelectronics and photovoltaics.