Polarity assessment of hydroxide mediated P(VDF-TrFE) composites for piezoelectric energy harvesting and self-powered mechanosensing

Abstract

Poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) commonly exhibits a very high degree of polarity in pristine condition. Still, highly piezoelectric inorganic fillers are incorporated into P(VDF-TrFE) to improve its piezoelectric energy harvesting performance and dielectric polarization. Here we incorporate a non-piezoelectric hydroxide filler, namely ZnSn(OH)₆ (ZS), into P(VDF-TrFE) and study the effect of this filler on the polarity and piezoelectricity of the resulting composite systems. The amount of polar phase of pristine P(VDF-TrFE) was observed to be as high as ∼88.5% which slightly increased to ∼91% for 1 wt% ZS loaded P(VDF-TrFE) and then abruptly decreased for higher amounts of filler loading. For the 10 wt% ZS loaded P(VDF-TrFE) the polar phase decreased to ∼56%. This result has been explained here on the basis of hydrogen bonding interaction which has been intentionally facilitated here through the use of a ZnSn(OH)₆ filler that contains a large number of –OH groups available for said interaction. The piezoelectricity of the composite films, as observed from PFM (Piezoresponse Force Microscopy) investigation, also showed a similar trend of variation of the piezoelectric properties of the composite films as compared to their polar phase. Owing to its high piezoelectricity, the 1 wt% ZS loaded P(VDF-TrFE) film was further used here for mechanical energy harvesting and different kinds of mechanosensing applications. The piezoelectric nanogenerator made up of this film delivered a high output power density (∼50 μW cm⁻²) with ∼83.5% efficiency.