Enhanced Thermoelectric Performance of Ultrathin Bi2Se3 Nanosheets through Thickness Control

Large‐scale Bi2Se3 nanosheets with controllable thickness have been synthesized by a microwave‐assisted solvothermal method. Through detailed structural characterizations, high‐quality Bi2Se3 nanosheets with average thickness of 1, 4, 7, and 13 nm have been fabricated. Their thermoelectric performance has been detailed investigated by experiments and fundamental nonparabolic Kane models. A significantly reduced thermal conductivity (only 0.41 W m‐1K‐1), and enhanced powder factor (4.71 × 10‐4 W m‐1K‐2 with a Seebeck coefficient of –155.32 μV K‐1 and an electrical conductivity of 1.96 × 104 S m‐1) are observed in the pellet composed of single‐layered Bi2Se3 nanosheets. Such an enhanced thermoelectric performance is ascribed to the broadened bandgap and optimized Fermi level in ultrathin Bi2Se3 nanosheets.