Researchers have developed a brand new organic thermoelectric device that may harvest energy from ambient temperature. While thermoelectric devices have several uses today, hurdles still exist to their full utilization. By combining the unique abilities of organic materials, the team succeeded in developing a framework for thermoelectric power generation at room temperature with none temperature gradient. Their findings were published within the journal Nature Communications.
Thermoelectric devices, or thermoelectric generators, are a series of energy-generating materials that may convert heat into electricity as long as there may be a temperature gradient — where one side of the device is hot and the opposite side is cool. Such devices have been a big focus of research and development for his or her potential utility in harvesting waste heat from other energy-generating methods.
Perhaps probably the most well-known use of thermoelectric generators is in space probes reminiscent of the Mars Curiosity rover or the Voyager probe. These machines are powered by radioisotope thermoelectric generators, where the warmth generated from radioactive isotopes provides the temperature gradient for the thermoelectric devices to power their instruments. Nonetheless, as a consequence of issues including high production cost, use of hazardous materials, low energy efficiency, and the need of relatively high temperatures, thermoelectric devices remain underutilized today.
“We were investigating ways to make a thermoelectric device that might harvest energy from ambient temperature. Our lab focuses on the utility and application of organic compounds, and lots of organic compounds have unique properties where they will easily transfer energy between one another.” explains Professor Chihaya Adachi of Kyushu University’s Center for Organic Photonics and Electronics Research (OPERA) who led the study. “A superb example of the facility of organic compounds may be present in OLEDs or organic solar cells.”
The important thing was to seek out compounds that work well as charge transfer interfaces, meaning that they will easily transfer electrons between one another. After testing various materials, the team found two viable compounds: copper phthalocyanine (CuPc) and copper hexadecafluoro phthalocyanine (F16CuPc).
“To enhance the thermoelectric property of this recent interface, we also incorporated fullerenes and BCP,” continues Adachi. “These are known to be good facilitators of electron transport. Adding these compounds together significantly enhanced the device’s power. Ultimately, we had an optimized device with a 180 nm layer of CuPc, 320 nm of F16CuPc, 20 nm of fullerene, and 20 nm of BCP.”
The optimized device had an open-circuit voltage of 384 mV, a short-circuit current density of 1.1 μA/cm2, and a maximum output of 94 nW/cm2. Furthermore, all these results were achieved at room temperature without using a temperature gradient.
“There have been considerable advances in the event of thermoelectric devices, and our recent proposed organic device will definitely help move things forward,” concludes Adachi. “We would love to proceed working on this recent device and see if we will optimize it further with different materials. We are able to even likely achieve a better current density if we increase the device’s area, which is unusual even for organic materials. It just goes to point out that organic materials hold amazing potential.”
