Dielectric Switching and Ferroelectric Studies of α, γ PVDF Phases for Energy Storage Properties

This article presents the current-voltage (I-V) characteristics, ferroelectric (P-E) and energy density properties of polyvinylidene fluoride (PVDF) film samples synthesized by melt-press and solution-cast techniques. Our earlier work reported the alpha and gamma -PVDF phase stabilization in PVDF film samples processed by melt-pressing and solution-casting respectively. In the present work, the I-V loops of pure PVDF film samples were recorded with variable delay time from 0.0005 to 1 s in order to understand the switching behavior response of molecular dipoles in different PVDF molecular conformations. The hysteresis behavior of I-V loops revealed the dominance of dipolar switching current in both the alpha and gamma-PVDF phases. The slim P-E hysteresis loops with low remnant polarization P-r values & AP;0.26 and 0.21 mu C/cm(2) at an applied electric field of 100 kV/cm for alpha and gamma -PVDF phases respectively were traced. The dielectric energy storage efficiency eta as calculated from P-E loop data was found to be & AP;37.7% and 38.6%, respectively, for alpha and gamma -phases of PVDF. The low leakage current and slim P-E hysteresis behavior in both the alpha and gamma -phases of PVDF are favorable or desired for their application in dielectric energy storage capacitors.