Enhancing Thermoelectric Performance of CuInTe₂ via Trace Ag Doping at Indium Sites

Abstract

Thermoelectric technology can be utilized to directly convert waste heat into electricity, aiming at energy harvesting in an environmentally friendly manner. As a promising p-type thermoelectric material, CuInTe 2 possesses a high inherent lattice thermal conductivity, which limits the practical implementation in the field of thermoelectricity. Herein, through the combination of vacuum melting and annealing along with hotpressure sintering techniques, we demonstrated that CuIn 0.95 Ag 0.05 Te 2 thermoelectric materials with trace Ag doping can exhibit a notably high Seebeck coefficient of 614 μV/K, arising from the high density-of-states effective mass and reduced carrier concentration. Owing to the diminished lattice thermal conductivity derived from Umklapp scattering induced by point defects and dislocation, stemming from the trace Ag doping at In sites rather than Cu sites, CuIn 0.95 Ag 0.05 Te 2 exhibited a maximum figure of merit (ZT) of 1.38 at 823 K, an 18% enhancement over pristine CuInTe 2 , leading to a maximum average ZT of 0.67 across temperatures ranging from 303 to 823 K. In essence, our work underscores the efficacy of doping engineering and point defects in tailoring the thermoelectric performance of CuInTe 2 -based materials. This study not only contributes to advancing the fundamental understanding of thermoelectric enhancement but also lays out a practical pathway toward the realization of high-performance CuInTe 2 -based thermoelectric materials.

Chemical Composition Modulation Realizing Remarkable Improvement of Thermoelectric Performance in CuInTe2-Based Alloy

“…However, achieving simultaneous regulation of electronic and phonon structures has proven to be challenging in many cases. That is, the phonon scattering increases as the elements or defects are controlled, but the electrical property degrades. − This is attributed to the shift of the Fermi level ( F r ) toward the conduction band minimum (CBM), preventing further improvement in the electrical property. − , For example, in the case of Cu 3.52 In 4.16 Te 8 with Cu 2 Te addition, the F r unpins and then moves toward CBM, resulting in a suppression of p-type carriers and no visible improvement in the electrical property (power factor) . On the other hand, however, the electrical property improves remarkably with the power factor (PF) reaching ∼15.0 μW/cm-K 2 while the phonon transport is not fully suppressed. , Facing this dilemma, the ongoing investigations, such as, band convergence and nestification, nanostructuring, lattice anharmonicity, and so on, can be recommended.…”