Trace Ag Doping at in Sites for Enhanced Thermoelectric Performance of Cuinte2

Abstract

Thermoelectric technology can be utilized to convert waste heat directly into electricity aiming at energy harvesting in an environmentally friendly manner. As a promising p-type thermoelectric material, CuInTe2 has a high inherent lattice thermal conductivity, which limits the application in the field of thermoelectric. Here, through vacuum melting and annealing along with hot-pressure sintering, we demonstrated that CuIn0.95Ag0.05Te2 thermoelectric materials with the trace Ag doping can exhibit a high S of 614 μV/K, resulting from the high density-of-states effective mass and reduced carrier concentration. CuIn0.95Ag0.05Te2 exhibited a maximum figure of merit (ZT) of 1.38 at 823 K, an 18% enhancement over pristine CuInTe2, leading to a peak average ZT of 0.67 at temperatures between 303 and 823 K. This is attributed to the low lattice thermal conductivity derived from the synergy between the enhanced configurational entropy and Umklapp scattering induced by point defects. It can be mainly attributed to the trace Ag doping at In sites rather than Cu sites. Our results help verify the efficacy of doping engineering and point defects in the formation of high-performance CuInTe2-based thermoelectric materials.

Keywords: thermoelectric material, CuInTe2, doping, lattice thermal conductivity, chalcopyrite