Large thermoelectric figure of merit in graphene layered devices at low temperature

TL;DR

This study demonstrates high thermoelectric figure of merit (ZT) in layered graphene devices at low temperatures by combining exfoliated graphene with phonon blocking materials, achieving ZT values up to 2.45.

Contribution

The paper introduces a novel layered device structure with graphene and phonon blocking materials that significantly enhances ZT at low temperatures.

Findings

Achieved ZT values between 0.81 and 2.45.

High ZT correlates with nanoscale surface properties.

Layered devices outperform pure graphene in thermoelectric performance.

Abstract

Nanostructured materials have emerged as an alternative to enhance the figure of merit (ZT) of thermoelectric (TE) devices. Graphene exhibits a high electrical conductivity (in-plane) that is necessary for a high ZT; however, this effect is countered by its impressive thermal conductivity. In this work TE layered devices composed of electrochemically exfoliated graphene (EEG) and a phonon blocking material such as poly (3,4-ethylenedioxythiophene)polystyrene sulfonate (PEDOT:PSS), polyaniline (PANI) and gold nanoparticles (AuNPs) at the interface were prepared. The figure of merit, ZT, of each device was measured in the cross-plane direction using the Transient Harman Method (THM) and complemented with AFM-based measurements. The results show remarkable high ZT values (0.81 < ZT < 2.45) that are directly related with the topography, surface potential, capacitance gradient and resistance of the devices at the nanoscale.