Abstract
A thin film of polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) has good flexibility and simple preparation process. More importantly, compared with PVDF, its piezoelectric β-phase can be easily formed without mechanical stretching. However, its piezoelectricity is relatively lower. Therefore, at present, PVDF-TrFE is always compounded with other kinds of piezoelectric materials to solve this problem. The effect of nano-ZnO doping amount on the sensing characteristics of the piezoelectric films was studied. PVDF-TrFE/nano-ZnO films with different nano-ZnO contents were prepared by spin coating process and packaged. The dispersion of nano-ZnO dopants and the crystallinity of β-phase in piezoelectric films with different nano-ZnO contents were observed by scanning electron microscopy and X-ray diffraction, and the piezoelectric strain constants and dielectric constants were measured, respectively. The effect of different nano-ZnO contents on the output performance of the piezoelectric sensor was obtained by a series of impact experiments. The results show that the piezoelectric strain constant and dielectric constant can be increased by doping nano-ZnO in PVDF-TrFE. Moreover, the doping amount of nano-ZnO in PVDF-TrFE is of great significance for improving the piezoelectric properties of PVDF-TrFE/nano-ZnO thin films. Among the prepared piezoelectric films, the output voltage of PVDF-TrFE/nano-ZnO piezoelectric sensor with 7.5% nano-ZnO doping amount is about 5.5 times that of pure PVDF-TrFE. Thus, the optimal range of the doping amount for nano-ZnO is about 4–10%.
Highlights
In recent years, more and more studies have focused on organic piezoelectric materials such as polyvinylidene fluoride (PVDF) series and its copolymer polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), because of their flexibility, low cost, and stable performance
Distributed in the PVDF-TrFE polymer, satisfying the assumption of the Yamada model [32,33], and doping content was less than 7.5%, the piezoelectric strain constant d33 increased with the increase of the β-phase crystallinity increased the doping increased
PVDF-TrFE/nano-ZnO films with nano-ZnO doping content of 1.5%, 4.5%, 7.5%, 10.5%, and 12.5% and pure PVDF-TrFE thin films were prepared by spin-coating method
Summary
More and more studies have focused on organic piezoelectric materials such as polyvinylidene fluoride (PVDF) series and its copolymer polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), because of their flexibility, low cost, and stable performance. With the decrease of ZnO nanoparticle size, the energy storage level of piezoelectric film increases linearly It has less influence on the crystallinity of PVDF-TrFE [24]. Various forms of nano-ZnO lead to different static friction and surface characteristics All these will undoubtedly affect the arrangement of PVDF-TrFE chains, resulting in obtaining different crystallinity and piezoelectric properties [26]. The above-mentioned studies have proved that the piezoelectric property of PVDF-TrFE can be improved by composting nano-ZnO, the influence of doping content is a another important factor that cannot be neglected. The effect of different nano-ZnO contents on the output performance of composite thin film was studied by using the proposed method. In contrast with other impact sensors, the sensitivity of our sensor can be improved and the doping amount of ZnO can be reduced
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