Large-area implementation and critical evaluation of the material and fabrication aspects of a thin-film thermoelectric generator based on aluminum-doped zinc oxide

TL;DR

This paper demonstrates a large-area, flexible thin-film thermoelectric generator using aluminum-doped zinc oxide, capable of powering wireless sensors at near room temperature with minimal heat leakage and stable long-term performance.

Contribution

It introduces a novel folded thin-film TEG design based on AZO material, enabling efficient heat flux and electrical current in the plane, with comprehensive performance evaluation and stability analysis.

Findings

Capable of powering wireless sensors in building environments.

Minimal heat leakage comparable to air, enabling low-temperature gradients.

Stable electrical and thermoelectric properties over several months.

Abstract

A large-area thermoelectric generator (TEG) utilizing a folded thin-film concept is implemented and the performance evaluated for near room temperature applications having modest temperature gradients (< 50 K). The TEGs with the area of ~0.33 m^2 are shown capable of powering a wireless sensor node of multiple sensors suitable e.g. for monitoring environmental variables in buildings. The TEGs are based on a transparent, non-toxic and abundant thermoelectric material, i.e. aluminium-doped zinc oxide (AZO), deposited on flexible substrates. After folding, both the electrical current and heat flux are in the plane of the thermoelectric thin-film. Heat leakage in the folded TEG is shown to be minimal (close to that of air), enabling sufficient temperature gradients without efficient heat sinks, contrary to the conventional TEGs having the thermal flux and electrical current perpendicular to the plane of the thermoelectric films. The long-term stability studies reveal that there are no significant changes in the electrical or thermoelectric properties of AZO over several months, while the contact resistance between AZO and silver ink is an issue exhibiting a continuous increase over time. The performance of the TEGs and technological implications in relation to a state-of-the-art thermoelectric material are further assessed via a computational study.