Increasing efficiency in thermoelectrics: 3D-printed hourglass structures improve performance

By using 3D printing technology, a research team has succeeded in significantly increasing the efficiency of thermoelectric materials. Thanks to a newly developed hourglass structure produced using 3D printing, efficiency has been increased by an impressive 360%.

The National Research Foundation of Korea announced that a joint research team led by Professor Jae Sung Son from POSTECH and Saniya LeBlanc from George Washington University has successfully developed a new shape for thermoelectric materials. Until now, these materials have typically been used in cuboid structures. The new hour-shaped geometry, which was produced using a special 3D printing process, promises a significant improvement in power generation efficiency.

Thermoelectric technology is a method of converting heat into electrical energy. This technology is increasingly seen as a sustainable energy source as it can convert heat from various sources such as factories, car engines and even human body heat into usable energy. So far, research in the field of thermoelectric generators has focused on improving material properties, especially the so-called Thermoelectric Figure of Merit (ZT). Despite these advances, however, the efficiency of thermoelectric generators has remained limited, highlighting the need for new approaches.

The research team demonstrated that simply by changing the geometry and composition of the materials, the efficiency of power generation can be maximized. In experiments in which eight different geometric structures were simulated and their efficiency measured, it was found that the hourglass-shaped geometry was the most efficient under all tested conditions. The researchers also developed a 3D printing process that makes it possible to produce complex-shaped thermoelectric materials with a high density of microlayers. These microlayers minimize thermal conductivity and increase the thermal efficiency (ZT) to a value of 2.0, the highest to date for thermoelectric materials produced using 3D printing.

Based on these results, the team fabricated thermoelectric generators with the different structures and found that the hourglass-shaped generator was about 3.6 times more efficient than a conventional generator with a rectangular base.

Professor Jae Sung Son stated, “This research is the first instance where efficiency has been improved by three-dimensional geometry of the material that controlled thermal and electrical transport, instead of conventional microstructure-focused research on thermoelectric materials. It is expected that this approach can be universally applied to all thermoelectric materials and can also be utilized in thermoelectric cooling technologies.”

This research was supported by the Korean government under the Mid-Career Researcher Program and the Nano and Material Technology Development Program and was recently published in the journal Nature Energy.