Rock-salt semiconductors such as PbTe and AgSbTe2 are current “state-of-the-art” thermoelectric materials with zT &gt; 2. However, given the toxicity of Pb and Te as well as the scarcity of Ag, alternative materials should be considered. Significantly understudied materials in the same family are APnE2 materials where A = (Li, Na, K), Pn = (Sb, Bi) and E = (S, Se). These materials are synthesized with a mild colloidal approach generating nanocrystalline material at relatively low temperatures. Synthesis of LiSbSe2, NaSbS2, NaSbSe2, NaBiS2, and NaBiSe2 will be discussed. Our method uses alkali metal hydrides, AH or carboxylates, A(O2CR), PnPh3, and elemental chalcogen as precursors, and oleylamine or 1-octadecene as solvent. While these materials have been characterized in bulk form previously, an in-depth analysis of the local structure has not been performed until now. These materials are prone to local distortions as Sb3+ and Bi3+ have a stereochemically active lone pair in various other materials. In addition, the alkali metal and pnictogen occupy the same crystallographic site, thus making it possible for local ordering of the cations. DFT is used to predict the lowest energy structure for various cation orderings. Pair distribution function reveals that Sb exhibits pronounced distortions from ideal octahedral coordination while Bi only exhibits small deviations. The thermoelectric properties of these materials will also be discussed.

Structure and properties of I-V-VI2 semiconducting nanocrystals

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.