Conductive Multilayer Films Research Articles

Preparation and characterization of ZnS/metal/ZnS transparent conductive multilayer films with different metal layers

ZnS/metal/ZnS transparent conductive multilayer films were deposited on quartz glass by pulsed laser deposition at room temperature with Au, Ag and Cu as the metal layers, and annealed in air at 100, 200 and 300℃ for 1 h. XRD patterns show that β -ZnS(111) diffraction peak of ZnS/Au/ZnS is stronger and sharper than the other two samples, indicating that its crystalline quality is the best. SEM images show the good structural homogeneity of the samples with smooth and compact film surfaces. When the annealing temperature increases from 100 to 300℃, the sheet resistance decreases first and then increases, while the carrier concentration changes in the opposite trend. The maximum transmittance (~85%) for ZnS/Au/ZnS in the visible light region is observed when the sample is annealed at 200℃. The figure of merit is calculated, and the best sample suitable for transparent conductive electrode is determined.

フレキシブルなAZO/Ag/Cu/AZO多層型透明導電膜の特性改善

フレキシブルなAZO/Ag/Cu/AZO多層型透明導電膜の特性改善

Conductive multilayer film based on composite materials made of conjugated polyelectrolytes and inorganic particles

Poly(3,4-ethylenedioxythiophene)–polystyrene sulfonate (PEDOT:PSS) conjugated polymer blend and a cationic poly(3-hexylthiophene) (P3HT)-based conjugated polyelectrolyte incorporating imidazolium ionic side groups were first adsorbed as monolayer on inorganic colloidal particles. At the plateau of adsorption isotherm, adsorbed amount of PEDOT:PSS on alumina particles appears lower than the adsorbed amount of P3HT on silica particles. Both polyelectrolytes strongly modify the surface charge of particles as reveals by zeta potential variation. Functionalized particles were then assembled using Layer-by-Layer method in order to prepare (PDDA/Al2O3-PEDOT:PSS)n and (SiO2-P3HT/PEDOT:PSS)n conductive multilayer film. Thicker PDDA/Al2O3-PEDOT:PSS films were elaborated when a drying step was added during the LbL build-up. The same effect was observed when composite particle concentration was increased from 1 to 10 g.L−1. Electrical behavior of film was completely modified in comparison with PDDA/PEDOT:PSS assembly. After heating at 150 °C, no conductivity was detected due to microcracks visible on SEM images. For SiO2-P3HT/PEDOT:PSS assembly, thickness is higher than for PDDA/Al2O3-PEDOT:PSS assembly using the same experimental procedure. However, even if two conductive polyelectrolytes were embedded into the film, conductivity was too low at 30 °C to be measured by van der Pauw technique probably due to the cracking of the film induced by incorporation of silica particles.

Development of Refractive-Index-Matched MTO/Ag/MTO Multilayer Film on Poly(ethylene terephthalate) Substrate

In this study, we fabricate a transparent conductive multilayer film consisting of an Ag layer sandwiched between manganese-doped SnO₂ layers (MTO/Ag/MTO) with a refractive index-matching layer (IML) on a poly(ethylene terephthalate) (PET) substrate. SiO₂ (n = 1.5 @ 550 nm) and MTO (n = 2.7 @ 550 nm) are selected as the low and high-refractive-index materials. In order to evaluate the reflectance (ΔR550 nm) and color difference (Δb*) properties relate to the electrode pattern visibility of transparent conducting oxide (TCO) films, we systematically investigate the influence of the SiO₂/MTO IMLs on the MTO (40 nm)/Ag (13 nm)/MTO (40 nm) TCO film. We find that the optical transmittance of all fabricated films are above 85% at a wavelength of 550 nm. The thickness of the IMLs exhibiting optimum characteristics is SiO₂ (70, 80, 90 nm)/MTO (10 nm). In addition, the ΔR550 nm and Δb* of the optimized films are 2.5, 2.1, and 1.6%, and 1.4, 1.1, and 0.7, respectively.

Characterization of Highly Conducting ZnMgBeGaO/Ag/ZnMgBeGaO Transparent Conductive Multilayer Films with UV Energy Bandgap

ZnMgBeGaO/Ag/ZnMgBeGaO multilayer structures were sputter grown and characterized in detail. Results indicated that the electrical properties of the ZnMgBeGaO films were significantly improved by inserting an Ag layer with proper thickness (~ 10 nm). Structures with thicker Ag films showed much lower optical transmission, although the electrical conductivity was further improved. It was also observed that the electrical properties of the multilayer structure were sizably improved by annealing in vacuum (~35% at 300 oC). The optimum ZnMgBeGaO(20nm)/Ag(10nm)/ZnMgBeGaO(20nm) structure exhibited an electrical resistivity of ~2.6 × 10−5 Ωcm (after annealing), energy bandgap of ~3.75 eV, and optical transmittance of 65%~ 95 % over the visible wavelength range, representing a significant improvement in characteristics versus previously reported transparent conductive materials.

Flexible and conductive multilayer films based on the assembly of PEDOT:PSS and water soluble polythiophenes

Flexible conductive polyelectrolyte multilayer films built upon anionic poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and cationic poly(3-hexylthiophene)-based conjugated polyelectrolytes (P3HT-R) containing imidazolium, pyridinium and phosphonium ionic groups were prepared using electrostatic layer-by-layer assembly. Adsorbed amount of each polyelectrolyte strongly increases when divalent cations (Ba2+) are employed as electrolyte and when the rinsing step is avoided during the build-up. The electrical properties of these (P3HT-R/PEDOT:PSS)n multilayer films were then investigated using the van der Pauw method leading to an average conductivity of ∼2 S m−1. Semiconducting behavior of these organic coatings was demonstrated by the direct relationship between the conductivity and the temperature. (P3HT-R/PEDOT:PSS)n multilayer films exhibited p-type semiconducting behavior as showed by Seebeck measurements. Finally, these films were successfully deposited onto flexible polymer sheets and their conductivity was found to be not affected by applying a bending stress.

Finite element analysis and equivalent parallel-resistance model for conductive multilayer thin films

The standard collinear four-point probe method is an indispensable tool and has been extensively used for characterizing conductive thin films with homogeneous and isotropic electrical properties. In this paper, we conduct three-dimensional (3D) finite element simulations on conductive multilayer films to study the relationship between the reading of the four-point probe and the conductivity of the individual layers. We find that a multilayer film may be modeled as a simple equivalent circuit with multiple resistances, connected in parallel for a wide range of resistivity and thickness ratios, as long as its total thickness is smaller than approximately half of the probe spacing. As a result, we may determine the resistivity of each layer sequentially by applying the four-point probe, with the original correction factor π/ln(2), after deposition of each layer.

Enhanced electrical and mechanical properties of rubber/graphene film through layer-by-layer electrostatic assembly

Despite a large amount of work have been carried out to prepare polymer/graphene hybrid nanocomposites, preparing rubber composites filled with graphene oxide via layer-by-layer (LBL) electrostatic self-assembly has not yet been reported. In this work, free-standing conductive multilayer film of (PEI/XNBR/PEI/GO)30 (30 is referred to the number of deposition cycles) was fabricated on glass substrate through alternative LBL self-assembly with graphene oxide (GO), carboxylic acrylonitrile butadiene rubber (XNBR) latex, and polyethyleneimine (PEI). During the self-assembly process, negatively charged carboxyl groups on XNBR latex and GO sheets can be electrostatically bound by positively charged amino groups from PEI molecules. After thermal treatment, XNBR latex particles in each layer are gradually mixed together and became a continuous rubber film layer, and partial ionic bonds among XNBR latex, PEI and GO sheets are changed into covalent amide bonds. The formation of the multilayer XNBR/graphene film with ordered arrangement of GO sheets and XNBR latex layers was demonstrated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The obtained XNBR/graphene film exhibited a significant improvement in mechanical properties, namely, 192% increase of the tensile strength and 215% increase of the elastic modulus. Besides, electrical conductivity of the prepared multilayer film reached 8.2E-03 S cm−1 after thermal reduced reaction. Hopefully, this prepared multilayer film may be potentially used as an elastomeric conductive material.

Effects of intermediate GAZO layer thickness on the properties of GAZO/Ag/GAZO/Ag/GAZO film

GAZO/Ag/GAZO/Ag/GAZO transparent conductive multilayer films were deposited by facing-target sputtering (FTS) methods at room temperature. As-deposited multilayer thin films consisted of Ag metal thin film layers and transparent conductive GAZO thin film layers. The fabricated multilayer thin films have a low sheet resistance and a high transmittance in the visible range. As a result, the sheet resistance, average transmittance in the visible range, and FOM (figure of merit) of the fabricated multilayer thin film with optimal layer thicknesses (50/12/75/12/50nm) were 2.7Ω/sq, 82%, and 4.9×10−2Ω−1, respectively (T: 0.82, Rsh: 2.7Ω/sq).

Investigation of ZnS–SiO2/Ag/ZnS–SiO2 as high stable transparent and conductive multilayer films

Novel transparent conductive ZnS–SiO2/Ag/ZnS–SiO2 multilayer films were prepared on K9 glass substrates by magnetron sputtering at room temperature. The structure of ZnS–SiO2/Ag/ZnS–SiO2 multilayer films were theoretically designed and the optimal thickness of each layer was determined (45nm/11nm/45nm). To obtain better optical and electrical properties, the ZnS–SiO2/Ag/ZnS–SiO2 samples were annealed at various temperatures. The optical, electrical, and structural characteristics of the ZnS–SiO2/Ag/ZnS–SiO2 multilayer films were then investigated. The results show that when the annealing temperature was 200°C, the sample exhibited a low sheet resistance of 9.7Ω/sq and a high optical transmittance of 88.4%. For the sample annealed at 200°C, the average transmittance in the visible range (380–780nm) was calculated and determined as 84.1%. The effects of humidity and temperature on the samples were assessed by an accelerated aging test. The results demonstrate the high damp heat stability of ZnS–SiO2/Ag/ZnS–SiO2 multilayer films.

Multilayer structured immunosensor based on a glassy carbon electrode modified with multi-wall carbon nanotubes, polythionine, and gold nanoparticles

An immunosensor for determination of salbutamol was developed. It based on glass carbon electrode (GCE) modified with a conductive multilayer film comprised of multi-wall carbon nanotubes, polythionine and gold nanoparticles. Salbutamol antibody was immobilized on the surface of the modified GCE which then was blocked with bovine serum albumin (BSA). The stepwise self-assembly process of the immunosensor was studied by cyclic voltammetry. The detection scheme is based on competitive binding of salbutamol to the sensor surface whose differential pulse voltammetric signal decreases after competitive binding of the salbutamol-BSA conjugate and free salbutamol to the salbutamol antibody. The sensor responds to salbutamol in 5 to 150 nM concentration range, with a detection limit of 1 nM. This method was applied to the precise and sensitive determination of salbutamol in spiked feed samples.

A label-free electrochemical immunoassay for IgG detection based on the electron transfer

In this study, a highly selective, label-free electrochemical immunoassay strategy based on the charge transport through the multilayer films associated with the electrocatalytic reduction of [Fe(CN) 6] 3− is proposed using human immunoglobulin G (human IgG) as the model analyte. The antibody–antigen complex formed on the sensing interface can efficiently induce change of the surface charge characteristics, the conductivity of multilayer film and/or electron transfer distance, resulting in an immunoreaction signal. The current reduction is proportional to the amount of analyte. Under the optimized experimental conditions, the proposed sensing strategy provides a linear dynamic range from 10 to 10 4 ng mL −1 and a detection limit of 3 ng mL −1, indicating an improved analytical performance. This possibly makes it a potential alternative in bioanalysis of proteins and other molecules.

Transparent Conductive Multilayer Films with Optically Clear Adhesive Interlayer for Touch Panel Devices

Transparent Conductive Multilayer Films with Optically Clear Adhesive Interlayer for Touch Panel Devices

Flexible multilayer electrode films consisted of polyaniline and polyelectrolyte by layer-by-layer self-assembly

In this research, we report the fabrication of flexible multilayer electrode films by layer-by-layer self-assembly (LBL-SA) technique. The conductive multilayer films consisted of weak cationic polyelectrolytes such as polyethylenimine (PEI)/poly(aniline) (PANi) and poly(allyamine hydrochloride) (PAH)/poly(aniline) (PANi) were fabricated on poly(ethylene terephalate) (PET) substrate coated with poly(diallyldimethylammonium chloride) (PDDA)/poly(sodium 4-styrenesulfonate) (PSS) under-layer. (PEI/PANi)20 film was covered with N,N-dimethylactamide (DMAC) to promote metallic ions and poly(vinylpyrrolidone) (PVP) layer was coated to avoid the hydrolysis of DAMC and metallic ion. The conductivity, morphology, and transmittance of electrode films were investigated by I–V characterization using the four terminal probe unit, atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and UV–vis spectrometry. The (PDDA/PSS)5/(PEI/PANi)20/(DMAC-Ag/PVP-Ag) electrode film fabricated on PET substrate showed the resistance of 15kΩ and transmittance of over 70%. These experimental results showed that the conductive films with uniformity and transparence were formed on the flexible PET substrate by LBL-SA method.

Properties of ZnO/Cu/ZnO multilayer films deposited by simultaneous RF and DC magnetron sputtering at different substrate temperatures

ZnO/Cu/ZnO transparent conductive multilayer films are prepared by simultaneous RF sputtering of ZnO and DC sputtering of Cu. The properties of the multilayer films are studied at different substrate temperatures. Sheet resistance of the multilayer film decreased initially with increase of substrate temperature and increased further with increase of substrate temperature beyond 100°C. However, transmittance of the multilayer film increased with increase of substrate temperature. Good transparent conductive film of sheet resistance 9.3Ω/sq and transmittance of 85% was found at a substrate temperature of 100°C. The performance of the multilayer film was evaluated using a figure of merit. The observed property of the multilayer film is suitable for the application of transparent conductive electrodes.

Construction of conductive multilayer films of biogenic triangular gold nanoparticles andtheir application in chemical vapour sensing

Metal nanoparticles are interesting building blocks for realizing films for a number ofapplications that include bio- and chemical sensing. To date, spherical metal nanoparticleshave been used to generate functional electrical coatings. In this paper we demonstrate thesynthesis of electrically conductive coatings using biologically prepared gold nanotrianglesas the building blocks. The gold nanotriangles are prepared by the reduction of aqueouschloroaurate ions using an extract of the lemongrass plant (Cymbopogon flexuosus) whichare thereafter assembled onto a variety of substrates by simple solution casting. Theconductivity of the film shows a drastic fall upon mild heat treatment, leading to theformation of electrically conductive thin films of nanoparticles. We have also investigatedthe possibility of using the gold nanotriangle films in vapour sensing. A large fall in filmresistance is observed upon exposure to polar molecules such as methanol, whilelittle change occurs upon exposure to weakly polar molecules such as chloroform.

Self-assembly and Characterization of Polypyrrole and Polyallylamine Multilayer Films and Hollow Shells

Conductive multilayer films have been fabricated from the alternating adsorption of the charged polymers, polypyrrole (PPy) and polyallylamine hydrochloride (PAH), on planar substrates as well as onto the surfaces of melamine formaldehyde (MF) microparticles based on the sequenced electrostatic layer-by-layer assembly technique. Hollow microcapsules are achieved after the removal of MF cores by dissolution in acid solution. The structure and conductive properties of the multilayer films and the hollow shells were characterized by UV−visible spectroscopy, phase contrast optical microscopy, atomic force microscopy, transmission electron microscopy, and scanning electron microscopy, respectively. The conductivity of all the composite films calculated from the measured resistivity is about 0.007 S/cm, which is comparable to other conductive polyelectrolyte films. The measurement of cyclic voltammetry showed that the PPy/PAH planar multilayer films, PPy/PAH-modified colloid particles, and hollow shells maintai...

The design of ZnS/Ag/ZnS transparent conductive multilayer films

In this paper, a ZnS/Ag/ZnS multilayer system for the transparent electrodes in flat panel displays was designed. The optical and electrical performance of an Ag and ZnS single layer films with nano-dimensions was investigated. The smallest thickness of the continuous single layer Ag film that could be deposited on SiO 2 surface by thermal evaporation is approximately 12 nm. The spectroscopic ellipsometry analysis indicated that the interlayer between the Ag and ZnS layer contains a physically mixed layer and a compound semiconductor layer. Based on these studies, according to the characteristic matrix theory, the design for the optimized system was carried out with complete searching strategy. A group of the optimized structures with good selective filtering performance were successfully prepared, including some new extremely asymmetric multilayer structures. These have low sheet resistance of 3 Ω/□ and a good spectral selectivity performance with luminous transmittance T lum approximately 90% and the reflectance near infrared region above 90%. The figure of merit F TC used for evaluating transparent electrodes reached 7.3×10 −2 at 550 nm wavelength.

Ａｇ‐Ｎｄ系合金を用いた透明導電性薄膜の電気的・光学的特性の評価

We investigated optical and electrical properties and durability in salt water of multilayer transparent conductive films with Ag-Nd alloy. By DC magnetron sputtering, we prepared three layer transparent conductive film with a structure of ITO/Ag-Nd alloy/ITO/substrate. As Ag-Nd alloy, we tried Ag-0.48 wt%Nd-0.60 wt%Au alloy and Ag-0.41 wt% Nd-0.56 wt%Cu alloy. We measured transmittance and sheet resistance of these transparent conductive films before and after dipping test in salt water. We found that before the dipping test, sheet resistance of the transparent conductive multilayer films with Ag-Nd alloy was almost the same as that with pure Ag. After the immersion of these transparent conductive films into salt water, we found that the durability of the transparent conductive film with Ag-Nd-Au alloy was superior to those with pure Ag and Ag-Nd-Cu alloy.

Optimum geometrical structure of highly magnetostrictive multilayer films for horizontally polarized high frequency magneto-surface-acoustic-wave propagation

Optimum geometrical structure of highly magnetostrictive multilayer films for the propagation of horizontally polarized magneto-surface-acoustic-wave (Love-type MSAW) was determined theoretically. The multilayered medium is composed of highly magnetostrictive alloy films and insulating films which are stacked alternately on a glass substrate. The analysis revealed that outstanding magnetoacoustic quantities comparable to those of an ideal nonconductive medium can be realized with the conductive multilayer films whose geometrical parameters meet the following conditions: DM/DL≥1, DM/DI≥10, and N∼20, where N is the number of insulating layers having the whole thickness of DI, and DM is the whole thickness of magnetic layers. DL is a limiting thickness of the magnetic film with a single-layer structure, above which the magnetoacoustic quantities are considerably deteriorated due to the micro-eddy current losses.