Nanostructural and piezoelectric characterization of electro-formed δ-phase poly(vinylidene fluoride) thin films

Ferroelectric polymer PVDF possesses different polymorphs. Solution-processed thin films crystallize mostly into the paraelectric alpha-phase. From alpha-PVDF, the electroactive phases beta-, gamma-, delta-PVDF can be achieved by further treatments. For instance, delta-PVDF, also known as alpha (p)-phase, can be obtained by electro-forming. In this work, we study the alpha-PVDF surface morphology using atomic force microscopy through a high-resolution image at the sub-nanometre scale. We go through the ferro- and piezoelectric properties of the electro-formed delta-PVDF thin films and we present an electro-mechanical characterization in high-fields regime, for studying the non-linear electrostrain behaviour, and in low-fields regime, for extracting the piezoelectric coefficient.