Development of Nanostructured BiTe with High Thermoelectric Performance by Scalable Synthesis and Microstructure Manipulations.

Nanostructuring of thermoelectric (TE) materials leads to improved energy conversion performance; however, it requires a perfect fit between the nanoprecipitates' chemistry and crystal structure and those of the matrix. We synthesize bulk BiTe from molecular precursors and characterize their structure and chemistry using electron microscopy and analyze their TE transport properties in the range of 300-500 K. We find that synthesis from BiO + NaTeO precursors results in n-type BiTe containing a high number density ( ∼ 2.45 × 10 m) of Te-nanoprecipitates decorating the BiTe grain boundaries (GBs), which yield enhanced TE performance with a power factor (PF) of ∼19 μW cm K at 300 K. First-principles calculations validate the role of Te/BiTe interfaces in increasing the charge carrier concentration, density of states, and electrical conductivity. These optimized TE coefficients yield a promising TE figure of merit () peak value of 1.30 at 450 K and an average of 1.14 from 300 to 500 K. This is one of the cutting-edge values recorded for n-type BiTe produced by chemical routes. We believe that this chemical synthesis strategy will be beneficial for future development of scalable n-type BiTe based devices.