By utilizing organic compounds like copper phthalocyanine and fullerenes, the device shows prospective in overcoming traditional thermoelectric limitations, opening the door to new energy-harvesting technologies.
While thermoelectric technology has potential for harvesting waste heat, its broader use has been limited due to high production costs, low energy efficiency, and the need for hazardous materials and high temperatures. In a new study led by Professor Chihaya Adachi from Kyushu University’s Center for Organic Photonics and Electronics Research (OPERA), researchers explored the use of organic compounds to address these challenges. Researchers have developed an organic thermoelectric device capable of harvesting energy from ambient temperature without the need for a temperature gradient.
Traditional thermoelectric devices rely on a temperature difference between a hot and cold side to generate electricity. These devices are widely used, particularly in space exploration, where they power probes like the Mars Curiosity rover and the Voyager probe. These probes utilize radioisotope thermoelectric generators, which create a temperature gradient by using heat from radioactive decay to generate electricity. Organic materials, already used in devices like OLEDs and organic solar cells, have the ability to transfer energy efficiently, making them suitable candidates for thermoelectric applications. The research team focused on developing a thermoelectric device that could function at room temperature without a temperature gradient.
After testing several materials, the researchers identified copper phthalocyanine (CuPc) and copper hexadecafluoro phthalocyanine (F16CuPc) as key compounds for their device. They enhanced the performance by adding fullerenes and BCP, known for facilitating electron transport. The final device configuration included a 180 nm layer of CuPc, 320 nm of F16CuPc, 20 nm of fullerene, and 20 nm of BCP. The optimized device produced 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 at room temperature without a temperature gradient. The team emphasized the potential of this new organic thermoelectric device and expressed plans to continue optimizing it with different materials and configurations, highlighting the promise of organic compounds in future energy technologies.
