Thermoelectric generators (TEGs) are devices that exploit the Seebeck effect – a phenomenon in which temperature difference produces a voltage difference between two electrical conductors – to generate an electrical current.
Around one sixth of energy generated for use in industry is emitted as waste heat, of which nearly 15% is economically viable for recovery, thus providing a commercial as well as environmental impetus for recovering industrial waste heat. This, combined with the potential for domestic waste heat recovery and even the micro-harvesting of human body heat to power personal consumer electronics, means that large area, flexible and printed thermoelectric generators could contribute significantly to energy efficiency and carbon reduction targets.
Until recently the majority of thermoelectric materials studied with promising ZT values (a measure of efficiency of heat conversion) have been based on alloys of elements like Bismuth, Tellurium, Antimony and Lead, some of which are toxic and/or rare. Researchers are increasingly turning their attention to organic materials as they are abundant, light-weight, flexible, solution-processable and low-cost, making large area printed devices a possibility. This makes waste heat recovery from large scale industry possible, as well as more bespoke applications such as wearable TEGs to power consumer electronics. In addition, two properties of organic conductors and semiconductors make them extremely promising as efficient thermoelectric materials: firstly, the thermal conductivity of organic materials is low (< 1 W m-1 K-1); secondly, organic conductors such as PEDOT:PSS are now achieving metal-like conductivity through process modification and doping. This means that organic materials could potential achieve high ZT values.
Thermoelectric material research at SPECIFIC involves organic, inorganic and hybrid materials that can be printed or solution processed. The ultimate goal is to manufacture building scale thermoelectric systems to utilise waste heat from buildings and industrial structures.
Contact: Dr Matt Carnie