Tuning thermoelectricity in a Bi₂Se₃topological insulator via varied film thickness

Abstract

We report thermoelectric transport studies on Bi 2 Se 3 topological insulator thin films with varied thickness grown by molecular beam epitaxy. We find that the Seebeck coefficient and thermoelectric power factor decrease systematically with the reduction of film thickness. These experimental observations can be explained quantitatively by theoretical calculations based on realistic electronic band structure of the Bi 2 Se 3 thin films. This work illustrates the crucial role played by the topological surface states on the thermoelectric transport of topological insulators, and sheds new light on further improvement of their thermoelectric performance. OPEN ACCESS RECEIVED

Topological insulators for thermoelectrics

“…Moreover, in TI thin films, the relative contribution of surface states to TE transport could be systematically controlled by varying the film thickness. This is demonstrated by a recent experiment on the epitaxial Bi 2 Se 3 TI thin films of varied thicknesses, 47 which shows that the metallic TI surface states become more and more important in thinner films, leading to decreased Seebeck coefficients and power factors. Further enhancement of TE performance can be expected by optimizing E F and introducing disorders or defects into the samples for utilizing the advantage of topological protection.…”

“…[37][38][39][40][41][42][43][44] Experimental measurements have also been taken to further investigate the contribution of TI boundary states to thermoelectricity. [45][46][47][48] …”

Focus on topological physics: from condensed matter to cold atoms and optics

“…In addition to the above theoretical progress, our focus issue also features experimental efforts towards the application of TIs as excellent thermoelectric materials. Guo et al [19] showed that TI thin films of Bi 2 Se 3 exhibit decreasing thermoelectric power factor with the reduction of film thickness, and provided a theoretical explanation. These results will shed light on future improvement of thermoelectric performance in TI materials.…”

Theoretical studies on tunable electronic structures and potential applications of two‐dimensional arsenene‐based materials

“…TIs are promising for thermoelectrics due to their topological protection, which enables an effective decoupling between electrons and phonons, thus realizing the concept of “electron‐crystal phonon‐glass” . Various novel thermoelectric effects have been demonstrated experimentally in TIs . The thermoelectric efficiency can be evaluated by its figure of merit, …”

“…[136][137][138] Various novel thermoelectric effects have been demonstrated experimentally in TIs. [139][140][141] The thermoelectric efficiency can be evaluated by its figure of merit,…”