The invention of a generator that extracts energy from heat at room temperature

Although they are less known than photovoltaics, thermoelectric generators (TEG) are excellent solutions for producing green electricity. This technology emerged in the 19th^e century and is mainly used to power probessuch as Voyager or New Horizons, as well as rovers like Perseverance. The size of the TEG market is expected to reach more than €6.7 billion by the end of 2030, according to Verified Market Reports. These devices are today the subject of numerous research aimed, among other things, at making them usable in more common applications. Among the research groups looking into this technology are scientists from Kyushu University. The latter have developed a thermoelectric generator operating without a temperature gradient.

A TEG operating thanks to charge separation

To operate, conventional thermoelectric generators need a thermal gradient, namely a high temperature part and a low temperature area. The electrons move in the device, from the hot surface to the cold one, thus generating an electric current. If this physical principle makes it possible to produce green electricity, by recovering lost heat, it makes the implementation of relatively complex generators. Indeed, they often require the use of expensive materials, such as bismuth tellurium, and must be installed in an environment with a certain temperature difference. To overcome this drawback, researchers at Kyushu University decided to use the phenomenon of charge separation. This principle allows negative electrons and positive electron “holes” to be separated, using heat, and moved in different directions to generate an electric current. The device developed by the team therefore does not need a thermal gradient and can operate at room temperature.

Results that confirm the researchers’ theory

In order to evaluate the performance of the thermoelectric generator using charge separation, the team of scientists from Kyushu University carried out tests and the results of the latter are rather promising. The researchers rated the device’s open circuit voltage at 384 mV, short circuit current density at 1.1 µA/cm² and maximum output power at 94 nW/cm². Certainly, these figures seem to be low, but you should know that the tests carried out on the thermoelectric generator took place at room temperature. In certain environments, it would therefore be possible to obtain better results.

A thermoelectric generator designed from organic materials

Unlike thermoelectric generators which, as we mentioned previously, are made from expensive metals, the one from the Kyushu University researchers is mainly made of organic materials. The device is composed of 20 nm fullerene, 20 nm bathocuproin, 320 nm hexadecafluoro copper phthalocyanine, and 180 nm copper phthalocyanine. The different layers of materials are arranged in a staircase. The lead author of the study, Chihaya Adachisaid they plan to improve the performance of the thermoelectric generator, by trying other organic compounds. He also added that it would be possible to obtain better current density, by increasing the surface area of ​​the device. More information here. An encouraging study for this device that is still not widespread and has a promising future, what do you think? I invite you to give us your opinion, your comments or point out an error in the text, click here to post a comment.