Strategic vacancy engineering advances record-high ductile AgCu(Te, Se, S) thermoelectrics.

Li, Nan-Hai; Shi, Xiao-Lei; Liu, Si-Qi; Li, Meng; Cao, Tian-Yi; Zhang, Min; Lyu, Wan-Yu; Liu, Wei-Di et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

AgCu(Te, Se, S) alloys, as one of the rare p-type plastic inorganic thermoelectrics, are receiving striking attention for their application foreground in high-performing flexible thermoelectric generators. However, strategies to enhance their thermoelectric performance while maintaining exceptional plasticity remain largely unexplored. Here, we introduce a strategic vacancy-engineering approach to address this challenge. Using computational design as a guide, we carefully tune the cation vacancy concentration to optimize hole carrier concentration, achieving impressive ZTs of ~0.62 at 300 K and ~0.83 at 343 K in (AgCu)<sub>0.998</sub>Te<sub>0.8</sub>Se<sub>0.1</sub>S<sub>0.1</sub>, ranking among the highest in this class of material. Importantly, numerous diffuse Ag-S bonds combined with amorphous phase introdeuced by vacancy engineering ensure that (AgCu)<sub>0.998</sub>Te<sub>0.8</sub>Se<sub>0.1</sub>S<sub>0.1</sub> retains high plasticity while having high performance. A novel flexible thermoelectric device, comprising ductile p-type (AgCu)<sub>0.998</sub>Te<sub>0.8</sub>Se<sub>0.1</sub>S<sub>0.1</sub> and n-type commercial Bi<sub>2</sub>Te<sub>3</sub>, achieves an impressive power density of ~126 μW cm<sup>-2</sup> under 25 K temperature difference, demonstrating significant application prospects for wearable electronics.