Corona Poling Process Research Articles

Topography and Nonlinear Optical Properties of Thin Films Containing Iodide-Based Hybrid Perovskites.

This article covers selected properties of organic-inorganic thin films of hybrid perovskites with the summary formulas CH3NH3MI3, where M = Pb, Cd, Ge, Sn, Zn. The paper discusses not only the history, general structure, applications of perovskites and the basics of the theory of nonlinear optics, but also the results of experimental research on their structural, spectroscopic, and nonlinear optical properties. The samples used in all presented studies were prepared in the physical vapor deposition process by using co-deposition from two independent thermal sources containing the organic and inorganic parts of individual perovskites. Ultimately, thin layers with a thickness of the order of nanometers were obtained on glass and crystalline substrates. Their structural properties were characterized by atomic force microscopy imaging. Spectroscopic tests were used to confirm the tested films' transmission quality and determine previously unknown physical parameters, such as the absorption coefficient and refractive index. Experimental results of the nonlinear optical properties were obtained by studying the second and third harmonic generation processes and using initial sample polarization in the so-called Corona poling process. The obtained experimental results allowed us to determine the second- and third-order nonlinear optical susceptibility of the tested materials.

Corona Poling Induced Phase Transition to Highly Polar Phase in P(VDF-TrFE-CFE) Dielectric and Charge Transport of Organic Field-Effect Transistors.

Increasing the number of charge carriers flowing through the charge transport channel to improve the electrical performance of organic field-effect transistors (OFETs) is important because it leads to a low driving voltage and a high drain current value. This paper proposes a new strategy, the corona poling process, to enhance the electrical performance of OFETs using an external electric field when forming a dielectric film using a PVDF-based high-k dielectric terpolymer, P(VDF-TrFE-CFE). A corona poling process was applied to align the dipoles with high-k dielectric molecules and improve the capacitance, thereby increasing the number of charge carriers. Through this process, by observing the phase transition of a PVDF dielectric through a corona poling process in the GIWAXS data, the phase transition through an external electric field was thoroughly revealed for the first time. As a result, the capacitance of high-k dielectric films can be improved, and the amount of charge carriers can be increased by a simple corona poling process. In addition, to reduce the effect of deep trap sites caused by the dipole alignment, a thin low-k dielectric, polystyrene (PS), was introduced between the active and high-k dielectric layers to provide trap site passivation, thereby increasing the electrical performance of the OFET. Therefore, through this strategy, using a diketopyrrolopyrrole (DPP)-based donor-acceptor (D-A) copolymer as an active material of OFET, the average saturation region hole mobility was improved from 0.34 to 0.60 cm2/Vs. Thus, the electrical performances of the OFETs were improved by enhancing the capacitance through the corona poling process and reducing the charge carrier trap sites introduced by the high-k and low-k bi-layer dielectric layer. Importantly, this work offers a new strategy for the post-treatment to improve electrical performance of organic devices.

Enhanced photocatalytic activity in ferroelectric BiFeO3 nanoparticles treated by a corona poling method

BiFeO3 particles of about 50 nm were prepared by the sol-gel method with the calcination temperature of 450°C. The corona poling treatment was carried out on BiFeO3 nanoparticles for different electric fields and duration time. XRD analysis reveals that the BiFeO3 nanoparticles maintain the stable perovskite structure before and after the poling treatment. Raman and XRD analysis respectively show that the Bi–O bonds stretched and the lattice distorted for BiFeO3 nanoparticles with corona poling treatment. The poled BiFeO3 nanoparticles exhibit better photocatalytic kinetics in degradation of methyl orange (MO) dyes under the visible light irradiation for 3 h, which is about 5.1 times better relative to the BiFeO3 nanoparticles without the poling treatment. We conjecture that the enhanced internal electric fields produced by the corona poling process may be beneficial to the reduction of the combination of photogenerated electron-hole pairs resulting in the enhanced photocatalytic activity of BiFeO3 nanoparticles.

A Review on 3D printing of piezoelectric materials

This paper presents an overview of 3D Printing methods of Piezoelectric materials [PEM] using various poling techniques, such as corona poling, contact poling, and other poling process, the method of integrating the 3D printing and poling, enables to print any type of sophisticated shaped sensors in single step, several conventional methods require complicated and time-consuming procedures, the 3d printing integrated with poling possess method and material constraints, the steps to minimize the technical challenges are under research.

Integrated 3D printing and corona poling process of PVDF piezoelectric films for pressure sensor application

This paper presents a novel process to fabricate piezoelectric films from polyvinylidene fluoride (PVDF) polymer using integrated fused deposition modeling (FDM) 3D printing and corona poling technique. Corona poling is one of many effective poling processes that has received attention to activate PVDF as a piezoelectric responsive material. The corona poling process occurs when a PVDF polymer is exposed to a high electric field created and controlled through an electrically charged needle and a grid electrode under heating environment. FDM 3D printing has seen extensive progress in fabricating thermoplastic materials and structures, including PVDF. However, post processing techniques such as poling is needed to align the dipoles in order to gain piezoelectric properties. To further simplify the piezoelectric sensors and structures fabrication process, this paper proposes an integrated 3D printing process with corona poling to fabricate piezoelectric PVDF sensors without post poling process. This proposed process, named ‘Integrated 3D Printing and Corona poling process’ (IPC), uses the 3D printer’s nozzle and heating bed as anode and cathode, respectively, to create poling electric fields in a controlled heating environment. The nozzle travels along the programmed path with fixed distance between nozzle tip and sample’s top surface. Simultaneously, the electric field between the nozzle and bottom heating pad promotes the alignment of dipole moment of PVDF molecular chains. The crystalline phase transformation and output current generated by printed samples under different electric fields in this process were characterized by a Fourier transform infrared spectroscopy and through fatigue load frame. It is demonstrated that piezoelectric PVDF films with enhanced β-phase percentage can be fabricated using the IPC process. In addition, mechanical properties of printed PVDF was investigated by tensile testing. It is expected to expand the use of additive manufacturing to fabricate piezoelectric PVDF-based devices for applications such as sensing and energy harvesting.

Enhanced charge generation of the ZnO nanowires/PZT hetero-junction based nanogenerator

We fabricated an alternative nanogenerator device with distinguished structure. Representative piezoelectric materials of ZnO nanowires and PZT thin films were tried to be combined to form a hetero-junction structure for fabrication of an alternative nanogenerator device to possibly obtain a synergy effect and then improved performance. The ZnO nanowires were grown by a hydrothermal synthesis technique and then PZT thin films were deposited on the surface of the ZnO nanowires by rf magnetron sputtering process. The PZT thin films were annealed to be crystallized with different conditions for post-deposition thermal treatment process. The hetero-junction structure was polarized by a Corona poling process to obtain a unidirectional orientation of dipole moments to enhance their piezoelectric property. Structure and morphology of the grown ZnO nanowires were investigated to achieve appropriate characteristics to achieve performance improvement for the resulting nanogenerator device. To confirm effect of the hetero-junction structure on improvement of power generation performance of the resulting nanogenerator device, current generating properties were comparatively investigated with those of nanogenerator device with only ZnO nanowires or PZT thin films as active piezoelectric component, respectively. The nanogenerator device with a hetero-junction structure of ZnO nanowires/PZT revealed distinctively improved average currents of 270nm, which is quite higher than those of the nanogenerator devices with pristine ZnO nanowires, or with pristine PZT thin films, respectively. Possible factors contributed to improvement of the current generation properties were discussed for the presented nanogenerator device.

Matrix Order Influence on the Non‐Linear Optical Properties of Dispersed Chromophore‐Azopolymer Systems

AbstractAzopolymers with moderate non‐linear optical (NLO) response are used as host matrices for a highly efficient molecule. The second harmonic intensity generated at room temperature by these binary systems increases noticeably by adding an irradiation step (406 nm) to the corona poling process. The free volume increase due to “trans‐cis” photoisomerization of the side‐chain azo moieties allows to align the NLO chromophores and causes, at least partially, this enhancement. In order to investigate the role of guest–host interactions on the NLO response, different matrix arrangements have been induced and different d33/d.

Synthesis and Characterization of New Disperse-Red Functionalized Polyimide for Use as Nonlinear Optical Material

A new thermally-stable second-order nonlinear optical polyimide with side-chain second-order nonlinear optical (NLO) chromophore was synthesized. First a diamine functionalized azo chromophore (9) was synthesized and then polymerized by reaction with 4,4′-hexafluro isopropylidene-diphthalic anhydride. The synthesized polymer had a glass transition temperature of 215°C. The corona poling process of the NLO-substituted polyimide was also studied in detail by measuring the second harmonic generation (SHG) from the polymer films. The second harmonic measurement indicate long-term stability of the dipole orientation (>500 h at 150°C) for this polyimide.

Second Order Nonlinear Optical Properties of Multifunctional Chiral Azobenzene Polymers

AbstractCorona poling behaviours of optically active photochromic copolymers derived from methyl methacrylate (MMA) and the methacrylic ester of (S)-3- hydroxy pyrrolidine linked through the nitrogen atom to the highly conjugated photochromic 4'-(β-cyano-β-(methylsulfonyl)vinyl)-4-azobenzene moiety, have been investigated with the aim to evaluate the effect on the non-linear optical (NLO) properties originated by the presence of inactive side-chain MMA groups along the main chain. The NLO properties of in situ corona poled polymeric films have been studied by second harmonic generation (SHG) measurements. The d33 values of the investigated polymers were determined to be in the range 10-86 pm/V after corona poling. The temporal and thermal stability of the optimal SHG signals obtained after corona poling process of all the macromolecular materials has been investigated and compared. The results indicate that the maximum of these properties can be obtained at a molar content of photochromic units around 20- 40%.

Growth of thin polymer films containing side-chain azo-dye analyzed by atomic force microscopy

Thin films containing both the azo-dye disperse red 1 (DR1) and the poly(methylmetacrylate) (PMMA) or the poly(phenylenevinylene) (PPV) are deposited by Langmuir–Blodgett and spin coating techniques on various substrates. The morphology, surface structure and growth pattern of the azo-dye-polymers were studied by atomic force microscopy. Nucleation and growth processes are responsible for the generation of different structures. The spin coated films were additionally oriented using the electric field poling method (corona poling). The film homogeneity is improved by this method in all cases. Due to the polar character of DR1 molecules, rod-like sub-structures are observed after the corona poling process in DR1–MMA films. The indium tin oxide surface enhances reorientation of the azo-dye-polymer molecules during corona poling and results in a significant reduction of the surface roughness.

Grazing incidence reflection absorption Fourier transform infrared (GIRA-FTIR) spectroscopic studies on the ferroelectric behavior of poly(vinylidene fluoride–trifluoroethylene) ultrathin films

Grazing incidence reflection absorption Fourier transform infrared (GIRA-FTIR) spectroscopy was used to characterize the ferroelectric behavior of a thin poly(vinylidene fluoride–trifluoroethylene) P(VDF–TrFE) copolymer. The lab-built GIRA-FTIR apparatus allowed the heating and corona poling process to be carried out whilst collecting the GIRA spectra of the thin polymer film. The Curie transition from the ferroelectric to paraelectric phase was confirmed from the abrupt change in intensity of the 849 cm −1 band in the RA-FTIR spectrum. It was found that the Curie temperature dropped dramatically when the film thickness was lowered to below a certain critical value of approximately 100 nm. The switching of the CF 2 dipoles in the ferroelectric crystals after applying the external electric field could be determined by monitoring the change in the 849 cm −1 band intensity. For the 600 nm thick P(VDF–TrFE) film, the switching of the dipoles appears to occur almost instantaneously, while the kinetics of dipole switching of the 75 nm thick film were significantly retarded. The repeated switchability of the CF 2 dipoles upon the application of a bipolar cyclic electric field was also confirmed. The bistability of the film due to remnant polarization was also confirmed from the absorbance of the 849 cm −1 band after removing the applied voltage during corona poling.

Electric poling in ultra-thin films of side group non-linear optical polymers studied by surface-enhanced Raman scattering

We have shown that surface-enhanced Raman scattering (SERS) techniques may be successfully applied to the corona poling process of ultra-thin films to explain the poling behaviors of the side group non-linear optical (NLO) polymers. The poling kinetics for a flexible backbone based on poly(methyl methacrylate) (PMMA) was described by the usual bi-exponential function. However, the poling kinetics for a rigid backbone system, poly( p-phenyleneterephthalates) to which the NLO chromophores, N-(4-nitrophenyl)-( l)-prolinol(NPP) were attached through flexible spacers were governed by a single rate process. This observation is explained in terms of a strong coupling between the rigid backbone and its side groups.

Low-Temperature Poling of Dye-Doped Polymers for Nonlinear Optical Devices

Abstract By repeating the corona poling process for several times, dye-doped polymer films were efficiently poled at temperatures significantly lower than Tg. High second-order NLO efficiency (e.g., d33 around 100 pm/V) was obtained with a guest dye, 2-(p-diethylaminocinnamilidene)-indan-1, 3-dione.

Corona poling and electroactivity in a side-chain methacrylate copolymer

The corona poling process and the decay in electro-optic activity were investigated for side-chain methacrylate (MA) copolymers functionalized with different weight percentages of chromophore disperse red-13. In order to obtain the maximum electro-optic activity, the efficiency of the corona poling process was investigated. The poling time, temperature and grid voltage of the corona triode were varied. Also, it was found that the electro-optic decay depends on chromophore content, temperature and the cooling rate of samples at the end of the poling process. Experimental data were fitted using the Kohlrausch-Williams-Watts (KWW) stretched exponential function and parameters depending on temperature and thermal treatment, and their relationship with the poling process is briefly discussed.

Fabrication of Surface Relief Grating with Second-Order Nonlinearity Using Urethane-Urea Copolymer Films

Surface relief gratings on azobenzene-substituted urethane-urea copolymer films with large second-order nonlinearity are fabricated by a laser-interferometric method. The surface relief structures are obtained upon exposure to an interference pattern of a polarized Ar+ laser beam, which mainly results from photoablation. The gratings are thermally stable at temperatures higher than glass transition temperature (Tg) of the copolymer. The surface relief gratings with second-order nonlinearity are fabricated after a corona poling process. We report what we believe to be the first experimental observation of the separated second-harmonic generation from the fundamental wave by the surface relief grating with second-order nonlinearity.

Synthesis and properties of a second-order nonlinear optical side-chain polyimide

A thermal stable aromatic polyimide (PI) with side-chain second-order nonlinear optical (NLO) chromophores has been developed. The PI was prepared by the ring-opening polyaddition of 4,4′-(hexafluoroisopropylidene)diphthalic anhydride with a new diamine having two N-ethyl-N-[4-[(6-chlorobenzothiazol-2-yl)diazenyl]phenyl]-2-aminoethanol units as the NLO chromophore, followed by poling during or after the thermal imidization process. The resulting PI had number and weight-average molecular weights (Mn, Mw) of 25,000 and 80,000, respectively, and a relatively high glass transition temperature of 180°C. The second harmonic coefficient (d33) of PI at the wavelength of 1.064 μm was 138 pm/V (329.6 × 10−9 esu) and remained unchanged at elevated temperatures. The corona poling process of the NLO-substituted poly(amic acid) to the PI was also studied in detail by measuring the second harmonic generation (SHG) from the polymer films. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1321–1329, 1999

In-Situ Electrochromic Studies of Corona-Poled Polymer Films

Real-time monitoring of the corona-poling process was accomplished by in-situ electrochromism of doped and functionalized polymer films. The poling properties including poling and depoling processes, dependence of orientation order parameter on poling time etc. of used films were investigated. The referential criteria for deciding the suitable poling conditions were suggested. Based on the one-dimensional rigid orientation gas model, the d33 of poled films was evaluated with the order parameter and bathochromic shift of maximum absorption of films independently. The results are in good coincidence.

Synthesis and Characterization of New Polyimide for Second-order Nonlinear Optics.

A new second-order nonlinear optical (NLO) polyimide (PI) with high thermal stability has been developed The PI was prepared by the ring-opening polyaddition of 4, 4′-(hexafluoroisopropylidene)diphthalic anhydride with a new diamine with two Disperse Red-I units, followed by poling during andafter the thermal imidization process. The glass transition temperature of PI was 182°C. The second harmonic coefficient (d33) of PI at the wavelength of 1.06μm was 116pm/V (278.6×10-9 esu) and remained unchanged at elevated temperatures. The corona poling process of the NLO substituted poly(amic acid) to the PI was also studied in detail by measuring the second harmonic generation (SHG) from the polymer films.

Blue and Green Second Harmonic Generation in Poled Polymer on the Inorganic Crystal Substrate

Abstract Optical second harmonic generation in the form of Cerenkov radiation is investigated using KH2PO4 (KDP) substrate and poled polymer thin film waveguide. The copolymer of MMA and DR1-substituted methacrylate molecules were oriented by corona poling process after spin coating on the KDP substrate. The conversion efficiency strongly depends on the waveguide geometry. The high conversion effficency is obtained by theoritical analysis when the nonlinear optical coefficient direction of a substrate is opposite to that of a waveguiding layer. In experiment, we haveconfirmed that the SH power by Cerenkov type phase matching using KDP crystal as a substrate is larger than that of using pyrex as a substrate.

In Situ Observation of the Orientational Motion of Chromophores during Corona Poling of Electro-Optic Polyimides

The corona poling process of electro-optic polymers has been investigated for rodlike aromatic polyimides doped with nonlinear optical chromophores. The dynamics of the chromophores in poling during and after imidization was observed by measuring second harmonic generation (SHG) from the polymer. In the course of poling during imidization, the SHG, observed before imidization, decreases to zero, reappears, and increases as the temperature increases. When poling was after imidization, the SHG intensity increased monotonically with increasing temperature. The disappearance of SHG in the poling during imidization is probably due to the known structural change in the polymer chains during imidization and the subsequent reorientation of the chromophores caused by formation of sheets of polyimides. The characteristics of the samples poled during and after imidization are nearly the same in both the extent of the nonlinear susceptibility and their thermal stability.