Solution-derived ferroelectric vinylidene fluoride oligomer thin films with large polarization

Dense and uniform vinylidene fluoride (VDF) oligomer thin films with a highly polar beta phase were prepared for the first time by a low-cost and scalable solution casting approach, after treatments of substrate surface functionalization and hot-pressing. Introducing hydrated salt in the precursor solution effectively promoted the ferroelectric beta phase. The VDF oligomer thin films obtained with short molecular chains exhibited high crystallinity and high remnant polarization (91 mC m(-2)), which is larger than both the polymer and copolymer counterpart films. The reasons for the observed low dielectric constant at low electric field, despite its larger polarization at high field, and the relatively high coercive field are discussed on the basis of the distinct structural characteristics of VDF oligomers. The low polar bulky end-groups and difficulties in kink formation and propagation may result in the observed low dielectric constant at low electric field and the high coercive field. (C) 2011 Society of Chemical Industry