With high carrier mobility and intrinsic low lattice thermal conductivity, Ag₂Se compounds have attracted increasing attention for thermoelectric application near room temperature. Due to its phase transition at ∼406 K and resulting thermal volume expansion, the growth and thermoelectric properties of large-sized Ag₂Se single crystals have seldom been reported so far. In this work, the vertical Bridgeman method was used for growing bulk Ag₂Se single crystal, with an orientation preference along low-symmetric (201) plane. The Hall mobility as high as 2 000 cm²/(V·s) and weak electron-phonon coupling contributes to a high electronic quality B_E of ∼7.0 in near-room-temperature β-Ag₂Se single crystals, which is superior to the high-temperature phase α-Ag₂Se. The observed low lattice thermal conductivity of 0.8 W/(m·K) at 300 K is due to the low group speeds and strong anharmonicity. A promising peak zT of 0.66 at 375 K and an average zT of 0.65 at 300–375 K were realized in β-Ag₂Se crystals. The low Vickers hardness and good ductile properties were confirmed by experiment and theoretical analysis. This work not only synthesized large-sized and highly-orientated Ag₂Se crystals, but also revealed its great potential of thermoelectric performance and mechanical properties for various applications near room temperature.

凭借高载流子迁移率和固有的低晶格热导率，Ag ₂ Se化合物在室温附近的热电应用中引起了越来越多的关注。由于其在~406 K的相变以及由此产生的热体积膨胀，大尺寸Ag ₂ Se单晶的生长和热电性能迄今为止鲜有报道。在这项工作中，垂直布里奇曼方法用于生长块状Ag ₂ Se单晶，其取向优先沿低对称（201）面。高达 2 000 cm ² /(V·s) 的霍尔迁移率和弱电子声子耦合有助于在近室温β下实现约 7.0 的高电子质量B _E-Ag ₂ Se单晶，其性能优于高温相α -Ag ₂ Se。在 300 K 时观察到的低晶格热导率为 0.8 W/(m·K)，这是由于低群速度和强非谐性所致。在β -Ag ₂ Se 晶体中实现了375 K 处 0.66 的峰值zT和 300-375 K 处 0.65 的平均zT 。通过实验和理论分析证实了其低维氏硬度和良好的延展性。该工作不仅合成了大尺寸、高取向的Ag ₂Se晶体，还揭示了其在室温附近各种应用的热电性能和机械性能的巨大潜力。