Radio frequency functional capacitors made of all-organic composites of thiourea in field-responsive polymers

By incorporating an organic high dielectric constant (K) ferroelectric crystal, thiourea, in field-responsive polymers, we fabricated radio frequency functional all-organic and solution-processable dielectric composites. Two field-responsive polymer matrices with polyvinylidene fluoride (PVDF) and pi-conjugated tris(8-hydroxyquinoline)aluminum(III) inclusions were used to fabricate six model high-kappa capacitor devices. Promising frequency-independent capacitance density of about 12 nF/cm(2) up to 100 MHz with an estimated k=54 was obtained from the model systems except when thin interpenetrating PVDF crystals formed within the amorphous matrix. These structures displayed significantly lower capacitance density (similar to 0.7 nF/cm(2)). High-k composites with low loss tangent (similar to 0.03) could be implemented in flexible electronics. (c) 2008 American Institute of Physics.