3D printing of highly aligned thermoelectric polymers

Thermoelectrics (TEs) are energy harvesters that convert waste heat into electrical energy and vice versa (they use electricity to provide active heating/cooling). Among the different classes of TE materials, organic TE materials present the advantages of being non-toxic, abundant and mechanically flexible. Therefore, organic thermoelectrics (OTEs) are perfect candidates to power wearable autonomous sensors integrated in smart textiles or even in direct contact with the skin. Such systems can find multiple applications in biomedicine and sports. The use of printing technologies facilitates the manufacture of OTE materials over large-areas. In particular, 3D printing is appealing because it allows the production of vertical structures with high aspect ratio and elaborated shapes. However, organic printed thermoelectrics suffer currently from low performances. Their performance depends not only on the material itself, but also on the way its molecules are arranged in the solid phase. The hypothesis of this project is the re-arrangement of the molecules in a way that they are all oriented in the same direction (molecular alignment) will lead to a boost in the thermoelectric performance of the organic material. In this project, the PhD candidate is expected to: 1- Develop a new setup combining micro-extrusion 3D printing with an external electric field (e-field) that will induce molecular alignment in the printed polymer leading to a boost in its TE performance. This Electric Field Assisted Molecular Alignment (EFAMA) 3D printing technology will also help improving the patterning resolution of the 3D structures. 2- Formulate commercial and customized (semi)conducting polymers with known TE properties as inks with the right rheology to be 3D printed with the developed setup. 3- Evaluate the effect of the printing parameters and e-field characteristics (AC vs DC, frequency and amplitude) on the final nanostructure and printing resolution. 4- Collaborate with other researchers in the group to characterize the nanostructure and TE performance of the printed material to validate the initial project hypothesis.