Super Large Sn1-xSe Single Crystals with Excellent Thermoelectric Performance

SnSe single crystals have drawn extensive attention for their ultralow thermal conductivity and outstanding thermoelectric performance. Here, we report super large Sn1-xSe 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 similar to 70 x 50 x 15 mm with a considerable weight of 148 g, which leads to a record-high mass density of >6.1 g cm(-3). Extensive chemical characterization demonstrates that similar to 0.3% Sn vacancies are present, which results in a large concentration of holes, similar to 1.2 x 10(19) cm(-3), and an enhanced power factor of similar to 6.1 mu W cm(-1) K-2 at 793 K. Simultaneously, the Sn-vacancy-induced lattice distortions result in a low thermal conductivity of similar to 0.39 W m(-1) K-1 at 793 K, leading to a competitive ZT of similar to 1.24. This work demonstrates that large-size off-stoichiometric SnSe single crystals hold promise to achieve high thermoelectric performance.