Simultaneous manipulation of electrical and thermal properties to improve the thermoelectric performance of CuInTe2

The unique transport properties make CuInTe2 emerge as a promising thermoelectric material. However, the intrinsically low carrier concentration and high lattice thermal conductivity of CuInTe2 limit its thermoelectric performance. In this work, firstly, we investigate the influence of excess Te on the electrical and thermal transport properties of CuInTe2. The results suggest that excess Te can act as both electron acceptors and phonon scattering centers, which simultaneously optimizes the carrier concentration and impedes the propagation of high-frequency phonons. Furthermore, the substitutional Ag/Cu defects integrated with excess Te lead to a further reduction in lattice thermal conductivity. DFT calculations indicate that the substitution of Ag for Cu can reduce phonon group velocity and intensify the acoustic phonon scattering, which agrees well with our experimental data. Finally, a high zT value of 1.03 is obtained @840 K for sample Cu0.8Ag0.2InTe2.2. This study demonstrates a facile but effective approach to boost the thermoelectric performance of chalcopyrite compounds.