Solution processable poly(vinylidene fluoride)-based ferroelectric polymers for flexible electronics

Since the discovery of piezoelectricity in poly(vinylidene fluoride) (PVDF) 50 years ago, ferroelectric polymers have established their own areas for research and applications due to their unique properties in comparison to single crystals and inorganics. PVDF is a semicrystalline polymer that can crystallize into five different polymorphs. Among them, the polar β-phase is the most interesting one for electroactive properties because it has the highest dipolar moment and the highest piezoelectric response. In the early days, the β-PVDF was typically produced by melt processing, limiting its form to free-standing films. The rapid development of flexible electronics, however, highly requires β-PVDF fabricated from solutions under mild conditions. The objective of this perspective is to summarize the effective methods to produce β-PVDF from solution, to present the approaches for enhancing the electroactive properties through morphological controls, and to discuss the applications of PVDF-based ferroelectric polymers in flexible electronics. In addition, current challenges that may impede the further development of this field are pointed out.