Synthetic Mechanisms in the Formation of SnTe Nanocrystals

Abstract

Infrared active colloidal semiconducting nanocrystals (NCs) are important for applications including photodetectors and photovoltaics. While much research has been conducted on nanocrystalline materials such as the Pb and Hg chalcogenides, less toxic alternatives such as SnTe have been far less explored. Previous synthetic work on SnTe NCs have characterized photophysical properties of the nanoparticles. This study focuses on understanding the fundamental chemical mechanisms involved in SnTe NC formation, with the aim to improve synthetic outcomes. The solvent oleylamine, common to all SnTe syntheses, is found to form a highly reactive, heteroleptic Sn-oleylamine precursor that is the primary molecular Sn species initiating NC formation and growth. Further, the capping ligand oleic acid (OA) reacts with this amine to produce tin oxide (SnO x ), facilitating the formation of an NC SnO x shell. Therefore, the use of OA during synthesis is counterproductive to the formation of stoichiometric SnTe nanoparticles. The knowledge of chemical reaction mechanisms creates a foundation for the production of high-quality, unoxidized, and stoichiometric SnTe NCs.

Bottom-Up Synthesis of SnTe-Based Thermoelectric Composites

“…This precursor allows producing pure SnTe at moderate decomposition temperatures. In contrast to previously reported procedures to produce SnTe nanocrystals, 73,76,77 the use of a Sn−Te precursor ink offers advantages in terms of the processability of printed SnTe-based devices. Besides, the SnTe ink can be combined with Cu 1.5 Te nanoparticles to produce Sn−Cu−Te nanocomposites upon thermal decomposition.…”