Anomalous suppressed thermal conductivity in CuInTe2 under pressure

Abstract

Pressure is an effective way to improve the thermoelectric performance by optimizing the electronic transport property. However, the increase in the thermal conductivity under pressure limits the improvement of thermoelectric properties. Here, based on the first-principles calculation and phonon Boltzmann transport equations, we find the unusual negative relation between the thermal conductivity and pressure in CuInTe2, i.e., its thermal conductivity along the c direction surprisingly decreases by 49% with applying the pressure from 0 to 7.7 GPa. This anomalous phenomenon mainly originates from remarkably enhanced phonon scattering rates under pressure due to dramatically softened transverse acoustic phonons and low energy optical phonons, which provide more phonon–phonon scattering channels. Our findings reveal the mechanism of decrease in the lattice thermal conductivity under pressure, which could be used for further improvement in the thermoelectric performance synergetically in the presence of pressure.