A revolutionary technology has been introduced that boosts the efficiency of thermoelectric materials, which are essential for transforming waste heat into electricity, by changing their shape to resemble an hourglass. This innovative method, unlike earlier studies that concentrated solely on the properties of thermoelectric materials, is anticipated to have extensive applications in the field of thermoelectric power generation.
The National Research Foundation of Korea, led by Chairman Lee Kwang-bok, revealed that a collaborative research team, guided by Professor Jae Sung Son from POSTECH and Saniya LeBlanc from George Washington University, has successfully created a new hourglass shape for thermoelectric materials that were previously limited to cubical forms, using geometric design and 3D printing techniques. This new configuration greatly enhances power generation efficiency.
Thermoelectric technology utilizes heat to generate electricity, making it an increasingly recognized sustainable energy source. It can convert heat produced by factories, vehicle engines, or even body heat into electrical energy. The core of this technology relies on solid thermoelectric semiconductor materials. Historically, studies on thermoelectric generators have prioritized enhancing the inherent properties of thermoelectric materials (known as the ZT value). However, even with advancements in ZT, the effectiveness of thermoelectric generators has not reached practical levels for daily use, highlighting the need for a new approach beyond mere material enhancement.
The research team has illustrated in their findings that simply adjusting the shape and composition of thermoelectric materials can optimize power generation efficiency. By experimenting with eight different geometric configurations, including both the traditional cuboidal shape and the innovative hourglass design, they discovered that the hourglass consistently outperformed all other shapes across various power generation conditions. Furthermore, the team refined their 3D printing techniques to create thermoelectric materials with complex shapes, resulting in high-density micro-layered defects that reduce thermal conductivity while raising the thermoelectric performance index (ZT) to an impressive 2.0, which is the highest recorded for 3D printed thermoelectric materials.
Based on their experiments, the researchers built thermoelectric generators using the eight distinct structures, and upon measurement, found that the hourglass-shaped generator operates approximately 3.6 times more efficiently than the traditional rectangular generator.
Professor Jae Sung Son remarked, “This research marks the first time efficiency has been improved through the three-dimensional geometry of the material that manages thermal and electrical transport, moving away from the traditional focus on microstructure in thermoelectric material research. This method is expected to be applicable to all thermoelectric materials and could also benefit thermoelectric cooling technologies.”
This significant achievement, bolstered by support from the Mid-Career Researcher Program and the Nano and Materials Technology Development Program under the Ministry of Science and ICT and the National Research Foundation of Korea, was published online on July 19 in the international journal Nature Energy.
