Systematic Enhancement of Thermoelectric Figure of Merit in Edge-Engineered Nanoribbons

Abstract

Nanomaterials provide unique promise to thermoelectric energy conversion owing to their possible phonon confinement and reduced thermal conductivity. These effects can, in particular, occur in nanoribbons upon edge-engineering. Here, we study graphene, boron nitride, and silicene chevron nanoribbons (CNRs) because of their high edge-length to surface area ratio to assess phonon boundary scattering effects on improving the thermoelectric figure of merit (ZT). The ab initio based nonequilibrium Green’s function method is utilized to calculate quantum electronic and phononic thermal conductance, electrical conductance, and Seebeck coefficient. Our results show that, compared to straight nanoribbons, ZT in CNRs is systematically enhanced. Detailed contributions to CNRs’ ZT for different geometries and materials are analyzed, in particular, separation of electrical and electron-contributed thermal conductance versus chemical potential. Taking the corresponding recent fabrications into account, edge-engineering of nanoribbons is shown to provide a possible strategy for achieving competitive thermoelectric energy conversion.

Recent advances in designing thermoelectric materials

“…2 shows the maximum ZT achieved for bulk thermoelectric materials over the past six years as a function of temperature. 33–234…”

Exploring Novel Flat-Band Polymorphs of Single-Layered Germanium Sulfide for High-Efficiency Thermoelectric Applications

“…These features are desirable for high electrical conductivity, large thermopower, and reduced thermal conductivity. − However, materials comprising all of these features simultaneously are hard to find. Meanwhile, another effective approach largely practiced for improving the ZT is introducing the above-mentioned features to the existing thermoelectric materials via dimensionality reduction. − This approach has been proved effective to enhance thermoelectric efficiency. For instance, reducing the dimensionality of the bulk Bi 2 Te 3 into the quantum well has improved its ZT of order 13 .…”