Infrared spectroscopic ellipsometry study of vinylidene fluoride (70%)-trifluoroethylene (30%) copolymer Langmuir–Blodgett films

Bai, Mengjun; Poulsen, Matt; Sorokin, A. V.; Ducharme, Stephen; Herzinger, C. M.; Fridkin, V. M.

doi:10.1063/1.1578697

Cited by 17 publications

(19 citation statements)

References 23 publications

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“…This validity of this assumption was confirmed by the polarized infrared studies. 17 In the visible and ultraviolet range, the copolymer films are transparent with very low absorption. 7,15 Cauchy dispersion functions were used to represent both in-plane and out-of-plane optical properties of the film, each with the form n( )ϭn 0 ϩb/ 2 ϩc/ 4 , and k( )ϭ␣ exp͓␤(1/ Ϫ1/ 0 )͔, where n 0 , b, c, ␣, ␤, and 0 , are constants.…”

Section: Resultsmentioning

confidence: 99%

“…To further reduce the correlation among the parameters in the fitting process and improve accuracy, a multi-sample data analysis technique was used. 17,[20][21][22] This technique fits the VASE data ͑ , ͒ and ⌬͑ , ͒ for samples with the same substrate properties, but different thickness d, and assumes that the optical constants n( ) and k( ) are independent of thickness ͑and that the films are uniaxial͒. As will be shown below, this is a good approximation for the copolymer LB film with the thickness ranging from 5 to 125 ML.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 3 shows the optical refractive indices n ʈ and n Ќ over the range 155-1700 nm, obtained from the VASE multi-sample analysis, plus the data from the infrared range 1.7-35 m reported in a previous article. 17 Table I two wavelengths with values reported in the literature for spin-coated films 7,8 and highly oriented ''single crystal-like films.'' 9 We calculated the expected values of n ʈ and n Ќ from the literature data by assuming that the LB films had uniform ͑110͒ crystal orientation perpendicular to the film, but are rotationally averaged in the film plane ͑hence the uniaxial model͒.…”

Section: Resultsmentioning

confidence: 99%

“…13 The highly oriented films 8 and extended-chain samples 9,14 have higher crystallinity and more uniform crystal orientation. The films made by the LB method are polycrystalline with chains parallel to the film, as revealed by x-ray diffraction 15,16 and polarized infrared spectra, 17 and seem to be without lamellar structure. Previoused reports give the optical refractive indices at only one or two wavelengths, and for partially oriented samples.…”

Section: Introductionmentioning

confidence: 98%

“…Detailed information about spectroscopic ellipsometry can be found in the text by Azzam and Bashara. 18 In a previous article, 17 we reported the results of VASE studies of the major vibrational modes of the ferroelectric copolymer Langmuir-Blodgett ͑LB͒ films in the spectral range 600-1600 cm Ϫ1 . We also a͒ Also with the Department of Physics, Ivanovo State University, Ivanovo 153025, Russia.…”

Section: Introductionmentioning

confidence: 99%

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Determination of the optical dispersion in ferroelectric vinylidene fluoride (70%)/trifluoroethylene (30%) copolymer Langmuir–Blodgett films

Bai

Sorokin

Thompson

et al. 2004

Journal of Applied Physics

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Bai, Mengjun; Sorokin, A.V.; Thompson, Daniel W.; Poulsen, Matt; Ducharme, Stephen; Herzinger, C.M.; Palto, S.; Fridkin, V.M.; Yudin, S.G.; Savchenko, V.E.; and Gribova, L.K., "Determination of the optical dispersion in ferroelectric vinylidene fluoride (70%)/trifluoroethylene (30%) copolymer Langmuir-Blodgett films" (2004 We report measurements of the optical dispersion in ferroelectric Langmuir-Blodgett films of polyvinylidene fluoride ͑70%͒-trifluoroethylene ͑30%͒ copolymer, using variable-angle spectroscopic ellipsometry over a wide spectral range from infrared to ultraviolet. Film thickness averaged 1.78Ϯ0.07 nm per deposition layer for films ranging from 5 to 125 deposition layers as determined from multi-sample analysis. This deposition rate was consistent with capacitance measurements, yielding a dielectric constant of 9.9Ϯ0.4 normal to the film, by quartz microbalance measurements, and by atomic force microscopy.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Determination of the optical dispersion in ferroelectric vinylidene fluoride (70%)/trifluoroethylene (30%) copolymer Langmuir–Blodgett films

Bai

Sorokin

Thompson

et al. 2004

Journal of Applied Physics

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Spatial and Frequency Selective Plasmonic Metasurface for Long Wavelength Infrared Spectral Region

Pan

Gao

et al. 2018

Advanced Optical Materials

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The development of novel approaches that control absorption and emission operating in long wavelength infrared (LWIR) spectral region is of fundamental importance for many applications, such as, remote temperature sensing, environmental monitoring, thermal imaging, radiation cooling and industrial facility inspections. A high performance plasmonic metasurface-based absorber for the LWIR spectral region is presented. In our design, a pyroelectric thin film, poly(vinylidene fluoridetrifluoroethylene) (P(VDF-TrFE)) copolymer, is introduced as spacer, that offers the device not only with multiple selective high absorption bands but also promising potential for application in optoelectronics. By employing a scattering-type near-field optical microscopy (s-SNOM), both the near-field amplitude and phase optical responses of the absorber are investigated at resonant wavelength, thereby providing direct experimental evidence to verify the nature of the absorption effect. To further demonstrate the versatility of our design, a particular metasurface patterned by the building blocks of the plasmonic absorber is fabricated and characterized. Two-dimensional hyperspectral images show that such a patterned structure exhibits both frequency and spatially selective absorption.

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A Scalable Nanogenerator Based on Self‐Poled Piezoelectric Polymer Nanowires with High Energy Conversion Efficiency

Whiter

Narayan

Kar‐Narayan

2014

Advanced Energy Materials

177

166

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nanowires, [ 7 ] PbZr x Ti 1-x O 3 nanowires [ 8 ] and nanoribbons [ 9,10 ] and poly(vinylidene fl uoride) (PVDF) nanofi bers [ 11 ] have all revealed promising energy harvesting performance. There has since been an ongoing concerted effort in developing this relatively new research fi eld, connecting nanotechnology with the fi eld of energy. [ 12 ] Piezoelectric nanowires are particularly attractive for energy harvesting due to their robust mechanical properties and high sensitivity to typically small ambient vibrations. [ 13 ] The implications of these properties, in fact, go beyond energy harvesting, as nanowirebased nanogenerators have recently been shown to function as bio mechanical sensors, [ 14 ] sensitive pressure sensors [ 15 ] and precision accelerometers. [ 16 ] The challenge lies in the large scale production of low-cost piezoelectric nanowires that can offer reproducible and reliable energy harvesting and/or sensor performance.The polymer PVDF [(CH2-CF2) n ] exhibits good piezoelectric and mechanical properties with excellent chemical stability and resilient weathering characteristics. [ 17,18 ] PVDF thin fi lms are thus commonly used as sensors and actuators. [ 19 ] However, the piezoelectric performance of PVDF is dependent on the nature of the crystalline phase present. Typically, PVDF occurs in the α, β and γ crystalline phases [20][21][22] and needs to be electrically poled (using an electric fi eld of the order of 100 MV m −1 ) and/ or mechanically stretched [ 20,22 ] to achieve the polar β-phase that shows the strongest piezoelectric behavior. [ 21 ] is a co-polymer that crystallizes more easily into the β-phase due to steric factors, [ 22 ] an advantage that we exploit in this work. Nanowires of PVDF and its copolymers have been previously incorporated into piezoelectric nanogenerators [ 11 ] but the relatively complex electrospinning fabrication process employed requires high voltages (5-50 kV) and specialized equipment. The associated high electric fi elds and stretching forces result in poled nanowires, however this fabrication process often suffers from poor control over nanowire size-distribution and alignment, and is yet to be conveniently and cost-effectively scaled up. [ 23 ] Here we report the growth of aligned P(VDF-TrFE) nanowires with a narrow size distribution using a simple, cost-effective and easily scalable template-wetting method, [ 24,25 ] where the template-induced space confi nement promotes high crystallinity and preferential orientation of the lamellar crystals in the polymer nanowires. [ 26,27 ] This results in the enhancement of piezoelectric properties, even without the need for electrical poling. A nanogenerator fabricated using template-grown, self-poled P(VDF-TrFE) nanowires is shown to have excellent electrical output when subjected to periodic vibrations. Using a circuit comprising a rectifi er to convert its AC output to DC, and a bank of capacitors to store the harvested energy, the nanogenerator is shown to be capable of lighting a commercial light emitting ...

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Infrared spectroscopic ellipsometry study of vinylidene fluoride (70%)-trifluoroethylene (30%) copolymer Langmuir–Blodgett films

Cited by 17 publications

References 23 publications

Determination of the optical dispersion in ferroelectric vinylidene fluoride (70%)/trifluoroethylene (30%) copolymer Langmuir–Blodgett films

Determination of the optical dispersion in ferroelectric vinylidene fluoride (70%)/trifluoroethylene (30%) copolymer Langmuir–Blodgett films

Spatial and Frequency Selective Plasmonic Metasurface for Long Wavelength Infrared Spectral Region

A Scalable Nanogenerator Based on Self‐Poled Piezoelectric Polymer Nanowires with High Energy Conversion Efficiency

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