Ultralow thermal conductivity and improved ZT of CuInTe2 by high-entropy structure design

Entropy engineering has been widely applied to thermoelectrics as an effective strategy to reduce thermal conductivity. On the other hand，the increase of configuration entropy certainly decreases the electrical conductivity simultaneously, leading to the worsening of the thermoelectric performance. In this paper, we report a study on the high entropy structure design for chalcogenide CuInTe2. Based on the analysis of electronic band structure, we show how to optimize the constituents of high-entropy compound to relieve the influence on electrical conductivity. Compared with (CuAg)0.5(ZnGeGaIn)0.25Te2, which has the highest configuration entropy among our samples, the optimized constituents of Cu0.8Ag0.2(ZnGe)0.1(GaIn)0.4Te2 shows the one order higher carrier mobility and little bit higher thermal conductivity. Finally, the highest ZT of 1.02 at 820 K is obtained in Cu0.8Ag0.2(ZnGe)0.1(GaIn)0.4Te2, accompanying with a very low thermal conductivity of 0.5 Wm−1K−1. This work provides a successful example of the high-entropy structure design for thermoelectrics, and it indicates that to reconcile the different requirements of thermal conductivity and electrical conductivity is crucial.