High Power Density for All‐Fe ₂ VAl‐based Thermoelectric Module by Enhancing the Power Factor of <i>p</i> ‐type Leg Through Defect‐Engineering and Wetting Effect

The high thermoelectric performance of Fe₂VAl stems from its sharply rising band edges on either side of the band gap, which is highly sensitive to composition. Addressing reproducibility and scale-up challenges, we have developed a strategy to enhance its p-type thermoelectric performance by defects and grain boundary engineering through regulating the V/Al ratio and In-doping in Fe₂V_0.85Ti_0.1Ta_0.05Al. p-type performance of Fe₂VAl has typically lagged behind n-type. In this work, a significant enhancement in power factor is realized near room temperature through a wetting effect. Additionally, a two-step metallization process is developed for both p- and n-type Fe₂VAl thermoelectric legs, allowing to achieve significantly low contact resistance and maximize power output. Ultimately, a high output power density of 624 mW/cm² with ΔT = 327 K is achieved for the All-Fe₂VAl two-pair module, 3.8 times the previous highest reported value. Despite its relatively high thermal conductivity, the impressive high power density makes it a possible choice for certain power generation and cooling applications, with benefits of material non-toxicity, inherent stability, and high mechanical strength. This study presents a novel approach to enhancing the thermoelectric performance of p-type Fe₂VAl through the wetting effect, achieving high output power density in abundant and relatively inexpensive All-Fe₂VAl-based devices.