Boosting High Thermoelectric Performance of n‐type AgBiSe ₂ via Rapid Synthesis Strategy

Owing to strong anharmonicity, n‐type AgBiSe 2 exhibits intrinsically ultralow lattice thermal conductivity, making it a promising thermoelectric material. However, its thermoelectric performance is constrained by poor electrical transport properties, while the time‐consuming synthesis methods further hinder the rapid validation of performance optimization strategies and scalability. In this work, a rapid synthesis strategy of self‐propagating high‐temperature synthesis was successfully adopted to prepare high‐purity AgBiSe 2 . The rapid synthesis process facilitated the formation of Se vacancies and domain structures, enabling simultaneous optimization of electrical and thermal transport properties. On the one hand, the electrical conductivity was significantly enhanced, reaching 365 S cm −1 at room temperature and 102 S cm −1 at 773 K. On the other hand, the lattice thermal conductivity reached a minimum value of 0.31 W m −1 K −1 at 773 K. Ultimately, a record‐high ZT value of 0.8 was achieved at 773 K for undoped n‐type AgBiSe 2 . Considering both the excellent thermoelectric performance and high synthesis efficiency, this rapid synthesis strategy is highly competitive and is expected to accelerate the development of AgBiSe 2 ‐based thermoelectric materials.