Enhanced functional and structural characteristics of poly(vinylidene- trifluoroethylene) copolymer thin films by corona poling

Electrical poling is of much interest for the enhancement of polarization properties of ferroelectric materials such as poly(vinylidene-trifluoroethylene) [P(VDF-TrFE)] in applications ranging from memory devices to piezoelectric actuation. Here, we report the changes in dielectric and optical properties correlated with structural modification of P(VDF-TrFE) thin films (<1 μm thickness) subjected to corona poling at low voltages (6 kV) under various thermal conditions. Enhanced crystallinity of hot-poled samples was observed independent of thermal history and crystalline structure, indicating the absence of recrystallization during poling. Absorption measurements confirmed the ordered structure in hot-poled samples due to the permanent orientation of the dipoles and higher crystallinity, thus resulting in increased and long-retained capacitance of the ferroelectric P(VDF-TrFE) capacitor device from high frequency C - V characterization. X-ray photoelectron spectroscopy further confirmed the shifting of C and F core orbitals to higher binding energy is related to formation of more ferroelectric phases by corona poling.