Enhanced thermoelectric performance and mechanical strength in GeTe enable power generation and cooling

Finding a real thermoelectric (TE) material that excels in various aspects of TE performance, mechanical properties, TE power generation, and cooling is challenging for its commercialization. Herein, we report a novel multifunctional Ge_0.78Cd_0.06Pb_0.1Sb_0.06Te material with excellent TE performance and mechanical strength, which is utilized to construct candidate TE power generation and cooling devices near room temperature. Specifically, the effectiveness of band convergence, combined with optimized carrier concentration and electronic quality factor, distinctly boosts the Seebeck coefficient, thus greatly improving the power factor. Advanced electron microscopy observation indicates that complex multi-scale hierarchical structures and strain field distributions lead to ultra-low lattice thermal conductivity, and also effectively enhance mechanical properties. High ZT ~ 0.6 at 303 K, average ZT_ave ~ 1.18 from 303 to 553 K, and Vickers hardness of ~200 H_v in Ge_0.78Cd_0.06Pb_0.1Sb_0.06Te are obtained synchronously. Particularly, a 7-pair TE cooling device with a maximum ΔT of ~45.9 K at T_h = 328 K, and a conversion efficiency of ~5.2% at T_h = 553 K achieving in a single-leg device. The present findings demonstrate a unique approach to developing superior multifunctional GeTe-based alloys, opening up a promising avenue for commercial applications.