Half-Heusler thermoelectrics: Advances from materials fundamental to device engineering

The potential widespread adoption of thermoelectric (TE) technology in energy harvesting applications hinges upon the high-performance, reliable, and cost-effective module development. Half-Heusler (hH) alloys show great promise, especially for efficient and reliable thermal to electrical energy conversion at medium to high temperatures, due to their tunable and favorable electronic structures, diverse routes to manipulate phonon transport, thermal stability, and robust mechanical properties. The remarkable progress observed in the performance of hH materials in the past decade has elevated expectations and opportunities to realize these materials in real-world applications. This review provides a comprehensive overview of the most promising strategies for achieving high-performance hH-based TE materials and device fabrication strategies that aim to accelerate the development of hH-based TE applications. Particular emphasis is given in this review to realize high-performance and high-temperature-compatible module designs, including interface design and module fabrication strategies. It covers material fundamentals leading to a high figure of merit (zT), interfacial engineering translating material properties into device performance, stability, and the rational design of devices for competitive energy efficiency. The review also explores the integration of data-driven science and additive manufacturing in hH TE materials and devices to stay at the forefront of material and device advancements. Concluding with a summary of persisting scientific challenges and unresolved fundamentals, the review offers perspectives for the future development of hH TE materials and devices. Similar strategies could be applied to other promising TE materials, achieving high-performance materials and module development.