Self-polarized Poly(vinylidene fluoride) Ultrathin Film and Its Piezo/Ferroelectric Properties.

Organic nonvolatile memory with ultralow power consumption is a critical research demand for next-generation memory applications. However, obtaining large area highly oriented ferroelectric ultrathin film with low leakage current and stable ferroelectric switching remains a challenge for achieving low operation voltage in ferroelectric memory transistors. Here, an ideal ferroelectric neat PVDF ultrathin film with high degree of orientation is fabricated by a melt-draw technique without post thermal treatment and assisted stabilization process. The PVDF ultrathin film is self-polarized with predominantly vertical orientation of dipole moments, exhibiting a d33 of 25 pm V-1 and the ultralow coercive voltage of approximately 3 V characterized by piezoresponse force microscopy (PFM). The remnant polarization (Pr) of 6.3 μC cm-2 is identified based on PVDF capacitor with active layer formed by six layers of the melt-drawn thin films. By employing a single layer melt-drawn PVDF ultrathin film as an insulation layer, a bottom-gate-top-contact ferroelectric field-effect transistor (FeFET) is fabricated with the very low operation voltage of 5 V. It exhibits a memory window with on/off current ratio of 1000 at zero gate bias and threshold voltage shift of around 2 V.