Researchers at the Queensland University of Technology (QUT) in Australia have developed a thin, flexible film that could power wearable devices using body heat, eliminating the need for batteries.

This technology could also be used to cool electronic chips, helping smartphones and computers run more efficiently.

Professor Zhi-Gang Chen, whose team’s research was published in the journal Science (www.science.org/doi/10.1126/science.ads5868), said the breakthrough tackled a major challenge in creating flexible thermoelectric devices that converted body heat into power.

This approach offers the potential of a sustainable energy source for wearable electronics, as well as an efficient cooling method for chips.

“Flexible thermoelectric devices can be worn comfortably on the skin where they effectively turn the temperature difference between the human body and surrounding air into electricity,” Chen said. “They could also be applied in a tight space, such as inside a computer or mobile phone, to help cool chips and improve performance. Other potential applications range from personal thermal management, where body heat could power a wearable heating, ventilating and air conditioning system. However, challenges like limited flexibility, complex manufacturing, high costs and insufficient performance have hindered these devices from reaching commercial scale.”

Most research in this area has focused on bismuth telluride-based thermoelectrics, valued for its properties that convert heat into electricity, which makes it suitable for low-power applications such as heart rate, temperature or movement monitors.

In this study, the team introduced a cost-effective technology for making flexible thermoelectric films by using tiny crystals, or nanobinders, that form a consistent layer of bismuth telluride sheets, boosting efficiency and flexibility.

“We created a printable A4-sized film with record-high thermoelectric performance, exceptional flexibility, scalability and low cost, making it one of the best flexible thermoelectrics available,” Chen said.

The team used solvothermal synthesis, a technique that forms nanocrystals in a solvent under high temperature and pressure, combined with screen-printing and sintering. The screen-printing method allows for the large-scale film production, while sintering heats the films to near-melting point, bonding the particles together.

Alongside Chen, QUT (www.qut.edu.au) researchers contributing to the study include first author Wenyi Chen, Xiao-Lei Shi, Meng Li, Yuanqing Mao and Qingyi Liu, all from the Arc Research Hub in Zero-emission Power Generation for Carbon Neutrality, the QUT School of Chemistry & Physics, and the QUT Centre for Materials Science.

Wenyi Chen said their technique could also work with other systems, such as silver selenide-based thermoelectrics, which were potentially cheaper and more sustainable than traditional materials.

“This flexibility in materials shows the wide-ranging possibilities our approach offers for advancing flexible thermoelectric technology,” he said.

Other members of the research team are Ting Liu, Matthew Dargusch and Jin Zou from the University of Queensland and Gao Qing (Max) Lu from the University of Surrey.