College of Materials , Shanghai Dianji University , Shanghai 201306 , P R China.
Ningbo Institute of Materials Technology and Engineering , Chinese Academy of Sciences , Ningbo 315201 , P R China.
ACS Appl Mater Interfaces. 2019 Feb 27;11(8):8051-8059. doi: 10.1021/acsami.8b21699. Epub 2019 Feb 15.
SnSe single crystals have drawn extensive attention for their ultralow thermal conductivity and outstanding thermoelectric performance. Here, we report super large SnSe single crystals with excellent thermoelectric properties, fabricated via an advanced horizontal Bridgman technique with great yield and high reproducibility. The obtained single crystals have a super large size of ∼70 × 50 × 15 mm with a considerable weight of 148 g, which leads to a record-high mass density of >6.1 g cm. Extensive chemical characterization demonstrates that ∼0.3% Sn vacancies are present, which results in a large concentration of holes, ∼1.2 × 10 cm, and an enhanced power factor of ∼6.1 μW cm K at 793 K. Simultaneously, the Sn-vacancy-induced lattice distortions result in a low thermal conductivity of ∼0.39 W m K at 793 K, leading to a competitive ZT of ∼1.24. This work demonstrates that large-size off-stoichiometric SnSe single crystals hold promise to achieve high thermoelectric performance.
硒化亚锡（SnSe）单晶体因其超低的热导率和出色的热电性能而引起了广泛关注。在此，我们报告了通过先进的水平布里奇曼技术制备的具有优异热电性能的超大 SnSe 单晶体，该技术具有高产量和高重现性。所获得的单晶体尺寸超级大，约为 70×50×15mm，重量相当可观，达到了 148g，从而实现了 >6.1gcm 的创纪录的质量密度。广泛的化学特性分析表明，存在约 0.3%的 Sn 空位，这导致了大量的空穴，约为 1.2×10cm，以及在 793K 时增强的功率因子，约为 6.1μWcmK。同时，Sn 空位引起的晶格畸变导致在 793K 时的热导率低至约 0.39WmK，从而获得了竞争力的 ZT 值，约为 1.24。这项工作表明，大尺寸非化学计量比 SnSe 单晶体有望实现高热电性能。
