Comprehensive Optimization of the Thermoelectric Properties of p-Type SiGe-Based Materials via In-Situ Decomposition of B4C

Silicon-based thermoelectric (TE) materials are demonstrating advanced capacity in environmental waste heat recovery. However, intrinsically high lattice thermal conductivity hinders the improvement of TE conversion efficiency. In the present work, a study of B4C composite for in situ nano-inclusions was carried out to enhance the TE properties of p-type Si80Ge20 materials. During sintering, B4C was demonstrated to form the SiC and B-rich ternary with a SiGe-based matrix, and the in situ formation of diverse nano-inclusions and the B dopant significantly reduced lattice thermal conductivity without deteriorating power factor (PF), weakening the coupling relationship between thermal and electrical transport properties to a certain extent. The carrier concentration of SiGe alloy samples was significantly increased, resulting in a 7.8% enhancement of PF for Si80Ge20B0.5-(B4C)0.3 at 873 K, while a low lattice thermal conductivity of 0.69 W m−1 K−1 is achieved. The optimal ZT is 1.08, which increased ~50% compared to the pristine sample, and an excellent average ZTavg of 0.62 is obtained among recent p-type SiGe-based TE materials’ works. Our research provides a new perspective for the optimization and practical application of p-type silicon germanium TE materials.