A fresh look at the potential of metallic thermoelectric materials

For decades, semiconductor materials have dominated thermoelectric research and their efficiency has been evaluated favorably through a dimensionless metric known as zT. Meanwhile, metallic and intermetallic compounds have been overlooked as the metric deemed them less efficient at converting heat into electricity.

Caballero-Calero et al. examined the efficacy of various metallic alloys and related intermetallic compounds, concluding that zT alone does not necessarily capture practical device performance. The materials, many of which rely on comparatively abundant, low-toxicity elements, combine a host of advantages: high power factor, mechanical robustness, tunable electronic structures, and compatibility with scalable processing routes.

“Metallic alloys and high-performance intermetallic thermoelectrics are connected by common physical design principles,” said author Olga Caballero-Calero. “Recognizing those connections can accelerate the discovery of new materials that combine performance, scalability, and a more responsible use of resources.”

The review suggests that high-power-factor metallic alloys are highly competitive with classical semiconductor materials in terms of near-room-temperature cooling and emphasizes nickel-gold as a scientifically important model system.

“While the cost and scarcity of gold limit direct large-scale deployment, it provides a blueprint for developing more sustainable high-power-factor alloys, such as copper-nickel or nickel-iron,” said author Cristina V. Manzano.

The study contends that a material with a high zT still may face barriers related to scarce elements, toxicity, costly processing, poor recyclability, or limited reliability. A metallic alloy with moderate zT, on the other hand, can possess excellent properties that may better serve specific cooling applications.

“Future progress will require an application-driven strategy: select and optimize materials according to the relevant thermal environment, device geometry, contacts, processing route, resource constraints, and end-of-life pathway,” said author Marisol Martín-González.

Source: “Sustainable thermoelectric materials based on metallic alloys and intermetallic compounds,” by Olga Caballero-Calero, Cristina V. Manzano, and Marisol Martín-González, APL Energy (2026). The article can be accessed at https://doi.org/10.1063/5.0341326 .

This paper is part of the Women in Energy Research Collection, learn more here .