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(-1) K-1), and enhanced powder factor (4.71 x 10(-4) W m(-1) K-2 with a Seebeck coeffi cient of -155.32 mu V K-1 and an electrical conductivity of 1.96 x 10(4) 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.