Enhanced thermoelectric performance in three-dimensional superlattice of topological insulator thin films
1 Department of Physics, and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian, 361005, People’s Republic of China
2 Fujian Key Laboratory of Semiconductor Materials and Applications, Xiamen University, Xiamen, Fujian, 361005, People’s Republic of China
3 Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen University, Xiamen, Fujian, 361005, People’s Republic of China
Nanoscale Research Letters 2012, 7:570 doi:10.1186/1556-276X-7-570Published: 16 October 2012
We show that certain three-dimensional (3D) superlattice nanostructure based on Bi2Te3 topological insulator thin films has better thermoelectric performance than two-dimensional (2D) thin films. The 3D superlattice shows a predicted peak value of ZT of approximately 6 for gapped surface states at room temperature and retains a high figure of merit ZT of approximately 2.5 for gapless surface states. In contrast, 2D thin films with gapless surface states show no advantage over bulk Bi2Te3. The enhancement of the thermoelectric performance originates from a combination of the reduction of lattice thermal conductivity by phonon-interface scattering, the high mobility of the topologically protected surface states, the enhancement of Seebeck coefficient, and the reduction of electron thermal conductivity by energy filtering. Our study shows that the nanostructure design of topological insulators provides a possible new way of ZT enhancement.