Strategic vacancy engineering advances record-high ductile AgCu(Te, Se, S) thermoelectrics
Nan‐Hai Li, Xiao‐Lei Shi, Siqi Liu, Meng Li, Tianyi Cao, Min Zhang, Wanyu Lyu, Wei‐Di Liu, Dongchen Qi, Zhi‐Gang Chen
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)0.998Te0.8Se0.1S0.1, 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)0.998Te0.8Se0.1S0.1 retains high plasticity while having high performance. A novel flexible thermoelectric device, comprising ductile p-type (AgCu)0.998Te0.8Se0.1S0.1 and n-type commercial Bi2Te3, achieves an impressive power density of ~126 μW cm−2 under 25 K temperature difference, demonstrating significant application prospects for wearable electronics. The authors report a vacancy engineering method to simultaneously optimize carrier concentration and maintain high plasticity, achieving a nearly 10% strain in three-point bending tests and a high ZT of ~0.83 at 343 K in (AgCu)0.998Te0.8Se0.1S0.1.