Enhanced thermoelectric figure of merit in polycrystalline carbon nanostructures

TL;DR

This study investigates how grain boundaries in polycrystalline carbon nanostructures can significantly enhance thermoelectric performance by affecting electron and phonon transport, suggesting new pathways for designing efficient thermoelectric materials.

Contribution

It demonstrates that grain boundaries can be used to improve thermoelectric figure of merit in carbon nanostructures, regardless of boundary type, through combined theoretical analysis.

Findings

Grain boundaries enhance thermoelectric figure of merit in carbon nanostructures.

The effect of grain boundaries on thermoelectric performance is largely independent of boundary type.

Polycrystalline carbon structures show potential for improved thermoelectric applications.

Abstract

Grain boundaries are commonly observed in carbon nanostructures, but their influence on thermal and electric properties are still not completely understood. Using a combined approach of density functional tight-binding theory and non-equilibrium Green functions we investigate electron and phonon transport in carbon based systems. In this work, quantum transport and thermoelectric properties are summarized for graphene sheets, graphene nanoribbons and carbon nanotubes with a variety of grain boundary types in a wide temperature range. Motivated by previous findings that disorder scatters phonons more effectively than electrons, a significant improvement in the thermoelectric performance for polycrystalline systems is expected. As the effect is marginally sensitive to the grain boundary type, we demonstrate that grain boundaries are a viable tool to greatly enhance the figure of merit, paving the way for the design of new thermoelectric materials.