Optimization of segmented thermoelectric devices composed of high-temperature thermoelectric material La2Te3

Thermoelectric materials can convert heat directly into electricity, and vice versa. As one of the excellent candidates for recovering the waste heat from industry and transportation, they have received extensive attention. The waste heat is widely dispersed and can be found in the temperature region from 323 K to higher than 1200 K. The composite materials have attracted much attention as popular materials in the field of thermoelectricity, and integrated high-temperature and low-temperature thermoelectric materials together to form a composite system with much higher thermoelectric superiority than single materials. Therefore, investigating thermoelectric materials suitable for high temperature is beneficial for their wider application. We have investigated the electric and thermoelectric properties of the novel high-temperature thermoelectric material La2Te3. A heavy-mass band occurs in the band structure and the figure of merit reaches 0.97 at 840 K. The optimal design variables were investigated to provide a reference for thermoelectric device design and applications. Comparing different sizes of the thermoelectric unit, the optimal segmented thermoelectric unit was obtained and the mechanism of performance improvement was explained. It was found that for a segmented thermoelectric device, there is an optimal length ratio for the n- and p-type thermoelectric materials corresponding to the maximum output power or highest conversion efficiency, but the optimal length ratios for the maximum output power and efficiency are different. Through simulation analysis and calculation, we found that the structure optimization can improve the output power and efficiency of the thermoelectric unit by 35.67% and 26.51%, respectively. In this paper, a high performance thermoelectric material La2Te3 was obtained through the theoretical calculation, and combined it with low- and medium-temperature thermoelectric materials to form a composite thermoelectric structure, and optimized the structure. This work provides a reference for the design and fabrication of high efficiency segmented thermoelectric devices.

Automated summary

This study investigated the performance of the high-temperature thermoelectric material La2Te3 and optimized its structure, providing a reference for the design and fabrication of high-efficiency segmented thermoelectric devices.