A conducting polymer as part of a thin-film thermoelectric device that can generate electricity from the temperature difference between the fingertips and the environment, has been made by scientists in South Korea. Organic thermoelectric materials that are flexible and non-toxic have only recently emerged, even though they are easily synthesized, lightweight and cheap. Such materials have the potential to be used in textiles and even turned into clothing that could use wasted body heat as an energy source. The researchers, led by Eunkyoung Kim from Yonsei University, optimised a polymerisation and electrochemical redox process to create conducting polymers based on poly(3,4-ethylenedioxythiophene (PEDOT) with good electrical conductivity and relatively high thermoelectric properties, reporting a power factor of more than 1260 µW m-1 K-2. This power factor is four times higher than that previously reported by Xavier Crispin and colleagues2 at Linköping University, Sweden who have also studied organic thermoelectric materials. Crispin is excited by Kim’s results: Conducting polymers are becoming almost as good thermoelectrically as state-of-the art bismuth antimony telluride alloys.
This research clearly shows another unique feature compared to inorganics: the mechanical flexibility of PEDOT- An efficient thermoelectric generator that is flexible; and can be integrated into textiles or clothes. The heating power of the human body, which varies between 7 and 40W, could be used to run low-power electronics and maybe extend the lifetime of the battery of mobile phone. The final objective of the research is to harvest energy from human body heat. The team plans to fabricate a thermoelectric device in the form of a cloth or belt, taking advantage of the flexible lightweight nature of the PP-PEDOT film. If such a device is successful, it could be used as a flexible and wearable thermoelectric device.