Large Area Thick Films of PVDF-TrFE and Relaxor-Ceramics for Piezo- and Pyroelectric Applications

Abstract

Wearable electronics, sensors, and energy harvesting devices are gaining an ever increasing importance in consumer products. Their success is, however, contingent on the availability of flexible and cost-effective functional materials. The present paper presents an up-scaled processing route for 0–3 thick film composites of the ferroelectric polymer polyvinylidenefluoride-trifluoroethylene and a relaxor ceramic. Different compositions are investigated for pyro- and piezoelectric applications. Various samples are produced via tape casting and spin-coating as freestanding and supported films of up to 600 × 200 mm² and on 150 mm silicon wafers, respectively. The samples are characterized in terms of thickness and roughness reproducibility, mechanical properties, and impedance. It is shown that good reproducibility and quality of the films can be realized. Depending on the application targeted (pyroelectric or piezoelectric), specific compositions together with the suitable poling process are presented. For instance, a composite with 24 vol% ceramic shows highest pyroelectric properties together with lowest piezoelectric thickness coefficient (d33) when poled for pyroelectric applications. On the other hand, a composite with 50 vol% ceramic exhibits a d33 of 100 pm V−1 that is unsurpassed for this type of composites. These properties are advantageous in a large variety of applications, including wearable devices.