Seebeck tuning in chalcogenide nanoplate assemblies by nanoscale heterostructuring.

Chalcogenide nanostructures offer promise for obtaining nanomaterials with high electrical conductivity, low thermal conductivity, and high Seebeck coefficient. Here, we demonstrate a new approach of tuning the Seebeck coefficient of nanoplate assemblies of single-crystal pnictogen chalcogenides by heterostructuring the nanoplates with tellurium nanocrystals. We synthesized bismuth telluride and antimony telluride nanoplates decorated with tellurium nanorods and nanofins using a rapid, scalable, microwave-stimulated organic surfactant-directed technique. Heterostructuring permits two- to three-fold factorial tuning of the Seebeck coefficient, and yields a 40% higher value than the highest reported for bulk antimony telluride. Microscopy and spectroscopy analyses of the nanostructures suggest that Seebeck tunability arises from carrier-energy filtration effects at the Te-chalcogenide heterointerfaces. Our approach of heterostructuring nanoscale building blocks is attractive for realizing high figure-of-merit thermoelectric nanomaterials.