Optimizing GeTe-based thermoelectric generator for low-grade heat recovery

Abstract

GeTe-based thermoelectric (TE) materials have been of great interest in the field of low-grade heat recovery due to their increasing performance near room temperature. To promote the application of GeTe-based materials, we analyze the GeTe-based thermoelectric generator (TEG) from materials to structures through theoretical and experimental methods. Since a TEG generally contains both p-type and n-type materials, we calculate the n-type material parameters suitable for the p-type GeTe, and improve the compatibility between p-type and n-type materials by adjusting the ratio of cross-sectional areas. Meanwhile, the height of TE legs is designed to minimize the impact of interfacial resistivity, while the suitable temperature loading is determined to achieve higher output power and conversion efficiency. Based on theoretical guidance, the conversion efficiency is improved by more than 23% by adjusting the ratio of cross-sectional areas; a conversion efficiency of 6.24% under the temperature gradient of 300 K is realized, which has up to 80% improvement from the conventional TEGs with the advantages of low cost, high reliability and stable service performance. This study provides the theoretical basis and guidance for optimizing GeTe-based TEG in the application of low-grade heat recovery.