Every year, two thirds of primary energy is released to the environment as waste heat. The re-utilization of the enormous amount of waste heat by means of conversion into electricity is of great significance to fight against climate change. Thermoelectric generators (TEGs) have therefore gained a large interest in both academia and industry. Large-scale manufacturing of low-cost shape-versatile TEGs is almost non-feasible by the well-estabilished bulk approaches, while implementing printing technology is a promising solution. To make conventional bulk thermoelectric (TE) materials printable, in other words, to enhance the rheological property of the TE inks, adding inorganic and polymeric binding components and solvents are necessary. These additional components, however, arise new issues with respect to interfacial transport. A high interface resistance and consequently a low device performance are now the main obstacles for printed TEGs to overcome.
In this project, we aim to develop new printed composite TE films with low interface resistance. To this end, site-specific analysis of charge-carrier transport at the interface is essential. Based on the complementary fields of expertise of the Heidelberg and KIT partners, this project will combine the formulation optimization of TE films (KIT group) and the electron-microscopic and -spectroscopic analysis (Heidelberg group). New TE inks will be designed, prepared and printed into TE thin-films, while their microstructure and interfaces within TE thin-films will be analysed in morphological and charge-transport perspectives. A correlation between the microstructural properties at the interfaces and the performance of the printed films will be established. The findings will pave the way to discovering new combinations of the TE phases in the printed films with high charge-transport performance.