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A5: Nanoscale and low dimensional effects
Topological insulators have been proposed to potential candidates for thermoelectric application. High figure of merit in topological insulator is due to combined effect of high mobility of surface electrons and bulk energy gap. In this talk, I will discuss the basics of thermoelectric and followed by the results of structural stability, electronic structure, and thermal transport properties of one to six quintuple layers (QLs) of Bi2Se3. The calculations have been performed using by van der Waals density functional theory and semi-classical Boltzmann theory. The bandgap amounts to 0.41 eV for a single QL and reduces to 0.23 eV when the number of QLs increases to six. A single QL has a significantly higher thermoelectric figure of merit (0.27) than the bulk material (0.10), which can be further enhanced to 0.30 by introducing 2.5\% compressive strain. Positive phonon frequencies under strain indicate that the structural stability is maintained.
