Anomalous piezoelectric properties of poly(vinylidene fluoride–trifluoroethylene)/ionic liquid gels

Abstract

Piezoelectric gels were prepared from low-volatile ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][TFSI]) gels, and their structural, ferroelectric, and piezoelectric properties were investigated. Poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE)/IL gels were formed using thermally reversible physical gels. The structural characterization indicated that the P(VDF-TrFE) molecules in the gels predominantly formed a ferroelectric phase (Form I) of P(VDF-TrFE). Polarization switching peaks were clearly observed using a three-layer stacked device structure. The coercive field of the P(VDF-TrFE)/IL gels substantially decreased to 4-9 MV/m, and their remnant polarizations were maintained at 63-71 mC/m 2 , which is similar to that for typical solid-state P(VDF-TrFE). Finally, the P(VDF-TrFE)/IL gel films exhibited a piezoelectric response, and the highest piezoelectric coefficient was >300 pm/V at an applied voltage frequency of 4 kHz.

New developments in composites, copolymer technologies and processing techniques for flexible fluoropolymer piezoelectric generators for efficient energy harvesting

“…Furthermore, the remnant polarization of this device is reported to be 64.3 mC m -2 , slightly lower than that of the pure PVDF-TrFE film. 200 On the other hand, the d33 value for the same device is measured at 129 pC N -1 , increasing to 381 pC N -1 for a device where the active layer consists of 87 wt% IL. 200 These values are approximately an order of magnitude higher than those of a PVDF-TrFE film and hence suggest that highly efficient flexible PEGs can be fabricated from these devices.…”

“…Fukagawa et al 200 have recently investigated the piezoelectric properties of the IL [Emim][TFSI] upon incorporation into PVDF-TrFE. This study utilized a three-layer PEG, where a gel layer of 79 wt% IL in PVDF-TrFE is sandwiched between two annealed films of PVDF-TrFE, with Al electrodes on the top and bottom of the resultant structure.…”

Soft Piezoionic/Piezoelectric Nanocomposites Based on Ionogel/BaTiO3 Nanoparticles for Low Frequency and Directional Discriminative Pressure Sensing

“…The choice of these relatively mild polarization conditions was due to the low tolerance of the ionogel matrix to high intensity electric fields and harsh temperature conditions, which may induce the polymer backbone degradation. 47 At the same time, we expected to obtain an adequate polarization of the piezoelectric material with lower coercive fields thanks to the presence of the ionic liquid, as previously demonstrated by Fukagawa et al 48 A schematic of the obtained poled piezoionic/piezoelectric nanocomposite is reported in Figure 3a, along with a photograph of a typical sample. The response to mechanical stimuli of both the pristine ionogel and the poled IG/BAT-Nc samples was assessed through open-circuit voltage measurements under a low intensity periodical driving force, at low frequencies.…”

“…The choice of these relatively mild polarization conditions was due to the low tolerance of the ionogel matrix to high intensity electric fields and harsh temperature conditions, which may induce the polymer backbone degradation . At the same time, we expected to obtain an adequate polarization of the piezoelectric material with lower coercive fields thanks to the presence of the ionic liquid, as previously demonstrated by Fukagawa et al…”

Hole Injection Characteristics and Annealing Temperature Dependence for Organic Light‐Emitting Diodes Using Spontaneous Polarization

“…In this study, poly (vinylidene fluoride-trifluoroethylene) [P(VDF/TrFE)] is used as a polar polymer with spontaneous polarization. [24][25][26][27] P(VDF/TrFE) is spin-coated on an ITO surface as a HIL. It does not affect the thickness of the OLED device because the P(VDF/TrFE) layer is ultrathinned by rinsing An efficient carrier injection at the electrode/organic semiconductor interface of organic light-emitting diodes (OLEDs) is challenging.…”