Synergistic boost of output power density and efficiency in In-Li-codoped SnTe.

We report enhanced thermoelectric performance of SnTe by further increasing its intrinsic high carrier concentration caused by Sn vacancies in contrast to the traditional method. Along with In2Te3 alloying, which results in an enhanced Seebeck coefficient, Li2Te is added to further increase the carrier concentration in order to maintain high electrical conductivity. Finally, a relatively high PF ave of ∼28 μW cm-1 K-2 in the range between 300 and 873 K is obtained in an optimized SnTe-based compound. Furthermore, nanoprecipitates with extremely high density are constructed to scatter phonons strongly, resulting in an ultralow lattice thermal conductivity of ∼0.45 W m-1 K-1 at 873 K. Given that the Z value is temperature dependent, the (ZT) eng and (PF) eng values are adopted to accurately predict the performance of this material. Taking into account the Joule and Thomson heat, output power density of ∼5.53 W cm-2 and leg efficiency of ∼9.6% are calculated for (SnTe)2.94(In2Te3)0.02-(Li2Te)0.045 with a leg length of 4 mm and cold- and hot-side temperatures of 300 and 870 K, respectively.