A groundbreaking organic thermoelectric device has been developed, capable of generating energy at room temperature without requiring a temperature gradient. This innovation, which utilizes the unique properties of organic compounds, could transform energy harvesting methods, making it possible to efficiently capture energy from ambient temperatures. The team’s findings were published on September 19 in Nature Communications.

Thermoelectric devices are known for their ability to convert heat into electricity when a temperature gradient exists. These devices have gained attention for their potential to capture waste heat from industrial processes and energy systems. The most well-known applications of thermoelectric generators include powering space probes, such as NASA’s Mars Curiosity rover and Voyager probe, where heat from radioactive isotopes creates the temperature gradient needed to generate electricity. However, the widespread use of these devices has been limited by high production costs, hazardous materials, low energy efficiency, and the requirement for elevated temperatures.

Professor Chihaya Adachi, from Kyushu University’s Center for Organic Photonics and Electronics Research (OPERA), led the research team that sought to overcome these challenges by exploring organic compounds. “We wanted to develop a thermoelectric device capable of harvesting energy from ambient temperature,” explained Adachi. “Organic materials, such as those used in OLEDs and organic solar cells, possess remarkable energy transfer properties, which we believed could be harnessed for thermoelectric applications.”

The researchers identified two key compounds that serve as effective charge transfer interfaces: copper phthalocyanine (CuPc) and copper hexadecafluoro phthalocyanine (F16CuPc). To enhance the performance, they also incorporated fullerenes and BCP, which are known for their ability to facilitate electron transport. The resulting device featured multiple layers, including 180 nm of CuPc, 320 nm of F16CuPc, 20 nm of fullerene, and 20 nm of BCP.

The optimized device achieved 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—all at room temperature and without a temperature gradient. This is a significant breakthrough in the field of thermoelectrics, as it eliminates the need for high temperatures and complex setups.

“This development marks a major step forward for thermoelectric devices,” said Adachi. “We are excited to continue refining the device with new materials and potentially increase its current density by scaling up its size. The potential of organic materials in energy generation is truly remarkable.”

With further optimization, this new organic thermoelectric technology could open doors to more efficient and scalable energy harvesting solutions, ultimately making it easier to capture ambient energy in everyday environments.

By Impact Lab