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Researchers at Queensland University of Technology (QUT) have made significant strides in identifying a novel material that shows promise as a flexible semiconductor suitable for wearable technology. This breakthrough stems from a technique that focuses on the manipulation of atomic spaces within crystalline structures.
In a recent publication in the journal Nature Communication, the research team applied “vacancy engineering” to improve the capabilities of an AgCu(Te, Se, S) semiconductor—an alloy comprising silver, copper, tellurium, selenium, and sulfur. This enhancement facilitates the conversion of body heat into usable electricity, opening new avenues for energy harvesting from the human body.
Vacancy engineering involves the intentional alteration of “vacancies,” or empty atomic sites, within a crystal. By adjusting these spaces, researchers can significantly influence the material’s mechanical properties and optimize its electrical and thermal conductivity.
The study featured contributions from first author Nanhai Li and his colleagues: Dr. Xiao-Lei Shi, Siqi Liu, Tian-Yi Cao, Min Zhang, Wan-Yu Lyu, Wei-Di Liu, Dongchen Qi, and Professor Zhi-Gang Chen. These researchers are affiliated with the ARC Research Hub for Zero-emission Power Generation for Carbon Neutrality, as well as the QUT School of Chemistry and Physics and the QUT Centre for Materials Science.
The article in Nature Communication outlines how the QUT team, guided by advanced computational design strategies, successfully synthesized a flexible AgCu(Te, Se, S) semiconductor using a straightforward and economical melting approach. Li noted that controlling atomic vacancies in the material not only enhanced its efficiency in converting heat to electricity but also provided it with outstanding mechanical attributes. This flexibility enables the material to be molded for various applications, making it particularly suitable for wearable technology.
To exhibit the potential real-world applications of this material, the researchers designed several micro-flexible devices that can be comfortably attached to a person’s arm. Li emphasized that the study tackled the dual challenge of enhancing the heat-to-electricity conversion efficiency of the AgCu(Te, Se, S) semiconductor while ensuring it maintains the necessary flexibility and stretchability for wearable use.
“Thermoelectric materials have gained considerable attention over the last few decades due to their distinct capability to convert heat into electricity without producing pollution or noise, and without the need for movable components,” Li remarked.
“The human body continuously generates heat, creating a temperature differential with the surrounding environment. Physical activities further amplify this temperature difference, making human body heat an ideal energy source.”
Professor Chen highlighted the urgent need for efficient flexible thermoelectric devices amid the rapid advancement of flexible electronics, positioning QUT researchers at the forefront of this critical area of study.
In a related investigation published in Science, Professor Chen and his team developed a cutting-edge ultra-thin, flexible film capable of harnessing body heat to power next-generation wearable devices, effectively negating the requirement for batteries.
“To propel the evolution of flexible thermoelectric technology, it is essential to explore a wide array of possibilities,” noted Professor Chen.
He elaborated, “Current mainstream flexible thermoelectric devices utilize inorganic thin-film materials, organic thermoelectric materials on flexible supports, and hybrid composites. Each category has its shortcomings; organic materials usually underperform, while inorganic options, despite offering superior thermal and electrical conductivity, often lack flexibility and tend to be brittle.”
“The semiconductor explored in our research is a rare inorganic compound with remarkable potential for flexible thermoelectric applications. However, the fundamental physical and chemical mechanisms that enhance its performance while preserving its pliability had not been thoroughly examined until now.”
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