A comprehensive understanding of the nano-structural effects that cause reduction in thermal conductivity represents important challenges for the development of thermoelectric materials with an improved figure of merit ZT. Bismuth telluride (Bi₂Te₃)-based thermoelectric materials exhibit very low levels of thermal conductivity. In this study, a Te crystal-embedded Bi₂Te₃ (Te–Bi₂Te₃) thin film was formed by establishing a specific annealing temperature for a Te-rich Bi/Te multilayered structure. Modulations in structure and composition were observed at the boundaries between the two phases of Te and Bi₂Te₃. Furthermore, the samples contained regularly shaped nanometer-scale Bi₂Te₃ single grains. Therefore, we obtained a dramatic ZT value of 2.27 (+ 0.04, − 0.08) at 375 K from the Te–Bi₂Te₃ thin film. Finally, we confirmed that interface phonon scattering between the Te–Bi₂Te₃ boundaries plays an important role in inter-grain phonon transport, which results in a reduction in the lattice thermal conductivity.

对导致导热系数降低的纳米结构效应的全面理解，对开发具有优异品质因数ZT的热电材料构成了重大挑战。碲化铋（Bi ₂ Te ₃）基热电材料的导热系数非常低。在这项研究中，通过为富Te的Bi / Te多层结构确定特定的退火温度，形成了嵌入Te晶体的Bi ₂ Te ₃（Te–Bi ₂ Te ₃）薄膜。在Te和Bi ₂ Te ₃两相之间的边界处观察到结构和组成的调节。此外，样品包含规则形状的纳米级Bi ₂ Te ₃单晶粒。因此，我们从Te–Bi ₂ Te ₃薄膜在375 K下获得了惊人的ZT值2.27（+ 0.04，-0.08）。最后，我们证实了Te–Bi ₂ Te ₃边界之间的界面声子散射在晶间声子传输中起着重要作用，这导致了晶格热导率的降低。