Thermoelectric study of Co2FeAl thin films grown onto flexible P(VDF-TrFE-CFE) terpolymer

Abstract

The necessity of energy conversion solutions has increased over the last years due to the necessity to power the small and flexible devices related to the Internet of things (IoT) concept. One of the most promissory ways to address this challenge relies on thermoelectric effects, such as the anomalous Nernst effect. Here flexible poly (vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) - P(VDF-TrFE-CFE) terpolymer sheet with high dielectric constant were produced by the doctor blade technique and used as the substrate to produce Co2FeAl/P(VDF-TrFE-CFE) heterostructures. The Co2FeAl layers were grown by magnetron sputtering with a thickness of 40 nm. The integration of P(VDF-TrFE-CFE) and magnetron sputtered Co2FeAl thin films allowed to explore the thermomagnetic properties of the composite through the Anomalous Nernst Effect and the influence of the flexible P(VDF-TrFE-CFE) substrate on this effect. The morphological, dielectric, and mechanical properties of the polymer were analyzed, as well as the structural, and magnetic properties of the magnetic thin films to support the thermomagnetic results. The Co2FeAl ferromagnetic thin films presented an isotropic magnetic behaviour, which was reflected in the thermomagnetic curves. Further, the curve's shape is stable irrespective of the thermal gradient and angle of the external magnetic field. The study demonstrates that it is possible to change from a rigid substrate (glass) to a flexible one (polymer), without affecting the thermomagnetic effect. Our findings open new possibilities to produce and integrate flexible high-dielectric polymers with thermomagnetic phenomena, which can be further explored for energy harvesting applications.