Resonant enhancement in nanostructured thermoelectric performance via electronic thermal conductivity engineering

TL;DR

This paper proposes using asymmetric broadening in resonant nanostructures to reduce electronic thermal conductivity, significantly boosting thermoelectric efficiency in both idealized models and realistic graphene nano-ribbons.

Contribution

It introduces a novel approach of electronic thermal conductivity engineering via resonant structures, supported by toy models and realistic graphene nano-ribbon calculations.

Findings

Electronic figure of merit can exceed 1000 in idealized models.

Realistic graphene nano-ribbons can achieve a figure of merit over 10.

Resonant structures effectively decrease electronic thermal conductivity.

Abstract

The use of an asymmetric broadening in the transport distribution, a characteristic of resonant structures, is proposed as a route to engineer a decrease in electronic thermal conductivity thereby enhancing the electronic figure of merit in nanostructured thermoelectrics. Using toy models, we first demonstrate that a decrease in thermal conductivity resulting from such an asymmetric broadening may indeed lead to an electronic figure of merit well in excess of 1000 in an idealized situation and in excess of 10 in a realistic situation. We then substantiate with realistic resonant structures designed using graphene nano-ribbons by employing a tight binding framework with edge correction that match density functional theory calculations under the local density approximation. The calculated figure of merit exceeding 10 in such realistic structures further reinforces the concept and sets a promising direction to use nano-ribbon structures to engineer a favorable decrease in the electronic thermal conductivity.