UV-Induced Ferroelectric Phase Transformation in PVDF Thin Films

Thin films of polyvinylidene fluoride (PVDF) enable access to efficient hybrid devices that operate at low voltages. However, the preparation of thin films from solution typically yields nonferroelectric crystalline phases that require additional processing steps to transform the nonferroelectric phases to the more desirable ferroelectric polymorphs. Here, a rapid photonic annealing technique is reported that induces an alpha- to beta-phase transformation in PVDF thin films, opening up the opportunity to process the material via high-throughput processing conditions such as roll-to-roll processing. This photonic annealing process uses a microsecond-scale light pulse to transform the spin-coated films into the desired ferroelectric PVDF phase. The structural evolution in these films is investigated under brief pulses of light, and it is shown that under optimal photonic annealing conditions, robust devices with a remnant polarization (P-r) up to 5.4 mu C cm(-2) and a coercive field (E-c) around 120 MV m(-1) can be achieved.