Impact of Copper Intercalation on Thermoelectric Properties in Polyol Method-Prepared CuxBi2Se3, X = 0, 0.05, 0.10, and 0.15 Nanosheets

Copper-doped single-phase nanosheets(NSs) of rhombohedral Cu x Bi2Se3, x = 0, 0.05, 0.10, and 0.15 withthe space group R3 m of crystallitesize in the range of 36-43nm and an average thickness of 41 nm have been synthesized successfullyin a modified polyol method using diethylene glycol (DEG) alone. Thermoelectric(TE) properties of these samples have been reported here. X-ray diffraction(XRD), X-ray photoelectron spectroscopy (XPS), and Raman study showthat Cu intercalates into the Bi2Se3 lattice.Notably, a large negative Seebeck coefficient with a relatively lowelectrical resistivity indicates their n-type semiconducting naturewith low energy charge filtering in the electrical transport. A 330%enhancement in the TE figure of merit (ZT) at 300K for x = 0.15 compared to that of x = 0 is observed due to the intercalation of Cu between quintuplesand energy filtering of carriers at grain boundaries (GBs), showinga good potential of this approach. Therefore, the Cu-intercalationapproach to enhance ZT has the potential to pavethe way for the future development of more efficient Bi2Se3-based TE materials that can operate effectively nearroom temperature.