Native Defect Engineering in CuInTe₂

Abstract

Ternary diamond-like semiconductors, such as CuInTe2, are known to exhibit promising p-type thermoelectric performance. However, the interplay between growth conditions, native defects, and thermoelectric properties have limited their realization. First-principles calculations of CuInTe2 indicate that the electronic properties are controlled by three dominant defects: VCu, CuIn, and InCu. The combination of these low-energy defects with significant elemental chemical potential phase space for CuInTe2 yields a broad phase width. To validate these calculations, polycrystalline, bulk samples were prepared and characterized for their structural and thermoelectric properties as a function of stoichiometry. Collectively, the off-stoichiometric samples show a range of carrier concentrations that span 5 orders of magnitude (1015 to 1019 h+ cm–3). Mobility of the off-stoichiometric samples suggests that copper vacancies act as strongly scattering point-defect sites, while the other native defects scatter less strongly. Such vacancy scattering extends to the thermal conductivity where a reduction in κL is observed and contributes to enhanced thermoelectric performance. Understanding and controlling the native defects in CuInTe2 provides a route toward n-type dopability as well as rational optimization of the p-type material.

Thermal Evolution of Internal Strain in Doped PbTe

“…16,17 Defect engineering is a promising materials design strategy for introducing phonon scattering centers and internal strain to improve zT. 18,19 When considering all possible chemical substitutions, defect reactions, experimental procedures, and resulting microstructures, the design space for defect engineering is vast. Therefore, detailed materials characterization throughout the synthesis process is important for designing better thermoelectrics.…”

Designing for dopability in semiconducting AgInTe2

“…As shown in previous works, [32][33][34] using the results of first principles calculations in conjunction eqn ( 1) is an effective approach for understanding defects in the context of experimental synthesis conditions. Here, we assume that defect concentrations are ''locked in'' at the synthesis temperature and cannot equilibrate to the measurement temperature, whereas electron and hole carriers can and do equilibrate.…”

Computational design of thermoelectric alloys through optimization of transport and dopability

“…Computations have greatly facilitated new TE materials discovery, 16–19 and their optimization through electronic doping. 13,20 At the same time, first-principles modeling of TE alloys has provided useful mechanistic insights; 10,21 however, a systematic computational framework for designing and optimizing TE alloys has not been demonstrated yet. In concert with high-throughput bulk synthesis, computations can provide guidance to navigate the continuous compositional space, and identify the optimal compositions in the multi-property phase space.…”