Second Phases and Dislocations to Boost the Thermoelectric Properties of CuInTe₂ by Sb Doping at In Site

Facing the severe energy crisis and environmental pollution, thermoelectric materials make full use of converting waste heat into electrical energy and have attracted considerable attention. Among these materials, CuInTe2 stands out as a potential thermoelectric material for application due to its low thermal conductivity. A series of Sb-doped CuInTe2 compounds are prepared successfully by vacuum melting, annealing, and hot-pressure sintering techniques. The Seebeck coefficient of CuIn0.90Sb0.10Te2 is enhanced, notably benefiting from an increased DOS effective mass and a trade-off between carrier concentration and mobility. Sb doping contributes to the formation of Sb-rich phases and dislocations, which effectively scatter phonons, resulting in a reduced lattice thermal conductivity. Due to the significantly increased Seebeck coefficient, a maximum power factor of 0.81 mW·m–1·K–2 is achieved at 823 K for CuIn0.90Sb0.10Te2, increased by 47% compared to pristine CuInTe2. The combination of the increased power factor and reduced thermal conductivity results in a maximum figure of merit (ZT) of 0.95 at 823 K for CuIn0.90Sb0.10Te2. The average ZT values from 323 to 823 K and from 523 to 823 K reach 0.38 and 0.59, respectively, enhanced by 66.7 and 64.7%, compared to that of pristine CuInTe2. Meanwhile, a calculated maximum energy conversion efficiency of ∼9.6% is achieved at ΔT = 500 K for CuIn0.90Sb0.10Te2. This work testifies to the effective utilization of doping engineering to enhance the thermoelectric properties of CuInTe2-based materials.