Thermoelectric energy harvesting is a technology that can be used to produce clean electricity out of any source of heat, which could be anything from high-temperature industrial processes to the heat given off by the human body. The TES-FlexThin project set out to combine thermoelectric energy harvesting with the capability of the atomic layer deposition (ALD) technique to fabricate hybrid inorganic-organic thin films in order to create flexible thermoelectric modules that could be used in applications such as wearable electronics. Such flexible energy harvesters could then enable the development of wearable devices or medical sensors that are powered entirely by human body heat.
Atomic layer deposition is a thin film deposition method based on sequential, self-limiting surface reactions between two or more precursor chemicals. The nature of ALD makes it possible to deposit materials one atomic layer at a time for excellent control over the thin film structure, and it can even combine inorganic and organic layers in the same film to create hybrid materials with unique properties. Flexible electronics are a typical example of what can be achieved with relatively simple inorganic-organic hybrids, and careful design of the layer structure in such materials can be used to substantially improve their thermoelectric properties.
The project demonstrated the design and fabrication of a prototype flexible thermoelectric module based on hybrid thin film materials. In addition, it was proven that ALD can be used to directly coat textiles with a thermoelectric material, which is highly useful for novel module concepts. The current design of the prototype modules is still a relatively simple one based on a single thermoelectric material, but this work will serve as the basis for further development of more efficient modules and designs with multiple materials for optimum performance. Although the technology is still at an early stage for commercialization purposes, its potential benefits were evidenced by the interest that several companies expressed in the project. Thus, it is strongly believed that the TES-FlexThin project will lead to new industrial cooperation projects and advance the development of applications based on flexible thermoelectrics.
