Inkjet printed tunable BST/P(VDF-TrFE) dielectrics on polymeric substrates for varactor applications

Ferroelectric materials are highly promising for dielectric properties in the field of flexible printed electronics as varactors due to their non-linear behavior. For the utilization in flexible films, composite inks consisting of ceramics and polymers are of great interest with BST/P(VDF-TrFE) being one of the promising choices. Herein, we are developing printable inks and studying the influence of ferroelectric ceramics (BST) and ferroelectric polymers (P(VDF-TrFE)) as well as non-ferroelectric ceramics (Al2O3) and non-ferroelectric polymers (PMMA). We were able to fabricate fully inkjet-printed BST/P(VDF-TrFE), BST/PMMA and Al2O3/P(VDF-TrFE) varactors with dielectric layer thicknesses between 1.24 and 1.70 μm. Dielectric investigations show that BST/P(VDF-TrFE) greatly outperforms the other systems and reaches a maximum tunability of 12.80% @40 V with a high Q factor of 27.7.