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.