Nanorods for flexible thermoelectric generator sheets
Researchers in the UK and Australia have developed an ultra-thin, flexible film using nanorods that could power next-generation wearable devices using body heat and can be used for thermal management for chips.
The team at the University of Surrey, UK, and the Queensland University of Technology (QUT) used flexible thermoelectric films by using tiny crystals, or “nanobinders”, that form a consistent layer of bismuth telluride sheets, boosting both efficiency and flexibility. These are linked by tellurium nanorods.
“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,” said Professor Zhi-Gang Chen at QUT.
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.
The flexible thermoelectric device has printable n-type Bi2Te3-based and p-type Bi0.4Sb1.6Te3 films and achieved a normalized power density of >3 μW cm−2 K−2, ranking among the highest in screen-printed devices.
“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,” said Chen.
“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.”
Alongside Professor Chen, QUT researchers contributing to the study include Wenyi Chen, Dr Xiao-Lei Shi, Dr 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 and Physics, and the QUT Centre for Materials Science.
Other members of the research team are Ting Liu, Professor Matthew Dargusch and Professor Jin Zou from the University of Queensland and Professor Gao Qing (Max) Lu from the University of Surrey.
The 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,” said Mr Wenyi Chen.
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