Thermodefect voltage in graphene nanoribbon junctions

TL;DR

This paper introduces the concept of thermodefect voltage in graphene nanoribbon junctions, showing how defects can significantly influence thermoelectric properties and potentially enhance nanomaterial performance.

Contribution

It presents the novel idea of defect-induced thermoelectric voltage in GNR junctions and analyzes how defects affect thermoelectric properties at room temperature.

Findings

Thermodefect voltage can reach 1.7 mV/K with specific defects.

Thermodefect voltage is highly sensitive to defect type, location, and GNR edge configuration.

Defects can be used to enhance thermoelectric performance of nanomaterials.

Abstract

Thermoelectric junctions are often made of components of different materials characterized by distinct transport properties. Single material junctions, with the same type of charge carriers, have also been considered to investigate various classical and quantum effects on the thermoelectric properties of nanostructured materials. We here introduce the concept of defect-induced thermoelectric voltage, namely, {\it thermodefect voltage}, in graphene nanoribbon (GNR) junctions under a temperature gradient. Our thermodefect junction is formed by two GNRs with identical properties except the existence of defects in one of the nanoribbons. At room temperature the thermodefect voltage is highly sensitive to the types of defects, their locations, as well as the width and edge configurations of the GNRs. We demonstrate that the thermodefect voltage can be as high as $1.7\,$mV/K for $555$-$777$ defects in semiconducting armchair GNRs. We further investigate the Seebeck coefficient, electrical conductance, and electronic thermal conductance, and also the power factor of the individual junction components to explain the thermodefect effect. Taken together, our study presents a new pathway to enhance the thermoelectric properties of nanomaterials.