High efficiency and thermal stability Bi₂Te₃-based thermoelectric modules via innovating amorphous high entropy barriers

To address the interfacial microstructure and property degradation issues during the high-temperature (473 K or above) long-term service of Bi₂Te₃-based thermoelectric (TE) modules, a novel NiCoFeMo high entropy alloy diffusion barrier with amorphous microstructure was proposed. The sluggish diffusion effect induced by thermodynamically high entropy, together with the elimination of diffusion paths along grain boundaries triggered by amorphous structures, jointly enhanced the interfacial thermal stability and conversion efficiency (η) of Bi₂Te₃-based TE modules. The two-pair bonded commercial Bi₂Te₃-based TE module showed an exceedingly competitive η of 6.6% under a temperature difference of 240 K. Besides, no degradation was observed at the Bi₂Te₃/NiCoFeMo interface after annealing at 523 K for 1000 h, a near-record duration at this temperature. This research offers new insights for fabricating long-term thermally stable TE modules with high η.