Search

• Nanometric films of Cu, Ni, Cu/Ni, and Ni/Cu were prepared by magnetron sputtering. • The electromagnetic shielding (EMI SE) of the films was evaluated in the X-band. • Bilayer films showed better EMI SE performance attenuating microwaves by almost 95 %. • The films showed microwave absorption mechanisms based mainly on dielectric losses. • Nanometric films showed potential as microwave absorbers being light and flexible. Modern developments in telecommunication and microelectronics have resulted in spurious radiation, which can promote electromagnetic interference and environmental pollution. To minimize this problem, this work studied nanometric metallic films (65 nm/layer) based on Cu and Ni and their combinations in bilayers deposited on a polyethylene terephthalate substrate by magnetron sputtering. Field emission gun scanning electron microscopy analyses showed that the films have different morphological textures, due to the processing parameters and the free energy of the metals. Electrical measurements by the 4-point method and dielectric spectroscopy showed that the films have low conductivity values, due to oxides formed on the surfaces of the films and defects. X-ray diffraction confirmed the formation of metallic oxides in the films. Electromagnetic characterization (8.2-12.4 GHz) of the monolayer films showed poor performance. Meanwhile, the bilayer films (Ni/Cu and Cu/Ni) showed different behaviors with reflection and absorption contributions. Attenuation values close to 95 % for the Cu/Ni film were obtained. [ABSTRACT FROM AUTHOR]

The article presents crystal structure, composition, optical, electrical and thermoelectric properties of semi-transparent CuI films produced in different modes of the cost-effective and large scalable method Successive Ionic Layer Adsorption and Reaction (SILAR) on flexible poly(ethylene terephthalate) (PET) substrates. The obtained data together with the analysis of output thermoelectric characteristics of p -type thermolegs based on these CuI films are used to select the SILAR mode to create semi-transparent p -type thermolegs for a new flexible wearable thin film thermoelectric generator (TEG). The best obtained flexible p -CuI thin film single thermoleg demonstrates output power 17.1 μW/m2 at the temperature gradient ∆ T = 35 K at near-room temperatures. Therefore, CuI films produced in such mode of the SILAR method on the flexible PET substrates can be used as a part of a new lightweight low cost flexible wearable thin film TEG for a production of electrical energy for low-power devices due to absorption of low-potential heat. • P-type copper iodide (CuI) thin films grown on flexible substrates. • Surface morphology, crystal structure, composition and optical properties studied. • Thermoelectric properties of p-type thermolegs based on CuI films presented. • Output thermoelectric parameters of flexible thin film thermolegs analyzed. [ABSTRACT FROM AUTHOR]

Chalcogenide PbS has been extensively studied as a p-type semiconductor material for various optoelectronic devices. Here, an effective two-step chemical bath deposition process is introduced to achieve dense microstructure of PbS thin films specifically for a flexible polyethylene terephthalate (PET) substrate. Three different types of substrates, such as Cu foils, glass substrate and PET, were initially examined to compare different crystal growth behaviors of PbS thin films depending on the choice of substrate. Only the PET substrate demonstrated an unacceptable coverage of films even with the extended deposition due to a retarded growth presumably with more scattered initial distribution of nuclei. Conclusively, two-step deposition processing at a low temperature of 40 °C for the PET substrate was successful in achieving homogeneous microstructures with proper bandgap and film thickness. As a promising result, the 60 min plus 60 min-double depositions at 40 °C produced an ideal bandgap of ~1.58 eV with a proper film thickness of ~200 nm. • Cu foil, polymer and glass substrates are compared with regard to PbS crystal growth. • Two-step chemical bath deposition is needed especially for polymer substrate. • The microstructural state by the first deposition is critical for homogeneous films. • Optical bandgap depends on the two-step deposition sequence. • An ideal bandgap of ~1.6 eV is achievable with the control of crystallinity. [ABSTRACT FROM AUTHOR]

Abstract Dry plasma reduction under atmospheric pressure is a unique approach for stably, continuously, easily, and uniformly fabricating Ag layer on the metal seeds-polyethylene terephthalate (PET) substrate. In this study, effects of particle size, surface uniformity, surface coverage, and film thickness of metal seeds such as Ag, Cu, Fe and Ni on the formation of uniform Ag layer were studied on the basis of their surface free energies and critical radius, which further leads to variations in the sheet resistance levels of the silver layers. The root mean square roughness and sheet resistance of the Ag layer PET substrate were decreased with the deposition of metal seeds. Among the added seed metals, Ni seed has shown best uniformity. Furthermore, the fabricated films were applied for electromagnetic interference (EMI) shielding. Among the added seed metals, Ni has shown the highest electromagnetic interference shielding effectiveness. The present study will be useful for the development of various low-cost metal films in the field of EMI shielding. Highlights • Uniform silver layer successfully fabricated with the aid of dry plasma reduction. • Fabricated films were applied as electromagnetic interference shielding materials. • Surface of silver layer formed more smoothly and uniformly by applying metal seeds. • The findings may be useful for the development of various low-cost metal films. [ABSTRACT FROM AUTHOR]

• Three multilayer films are deposited on flexible substrates with ion-beam assisted deposition. • A phase-shifting shadow moiré interferometer used to measure the residual stress. • The different relative elasticity could potentially be used for stress relief. • The anisotropic stress of these multilayer films are analyzed with Mohr circle method. This study simulates and tests various prototype multi-layer films on polyethylene terephthalate (PET) and polycarbonate (PC) substrates. The optical and stress response properties of three commonly used optoelectronic anti-reflector (AR) coatings (TiO 2 /SiO 2)2, (Ta 2 O 5 /SiO 2)2 and (Nb 2 O 5 /SiO 2)2 were determined. A lab-designed phase-shifting shadow moiré interferometer and Mohr circle approach were used to collect and interpret data. Results showed that the refractive indices of the four different dielectric films were 2.24(TiO 2) > 2.23(Nb 2 O 5) > 2.1(Ta 2 O 5) > 1.44(SiO 2). The transmittances of the three different AR coatings, in decreasing order, were 95.28%(Ta 2 O 5 /SiO 2)2 > 94.86%(TiO 2 /SiO 2)2 > 94.03%(Nb 2 O 5 /SiO 2)2. The maximum shear stress of three different AR coatings, in decreasing size, were (Nb 2 O 5 /SiO 2)2 > (Ta 2 O 5 /SiO 2)2 > (TiO 2 /SiO 2)2, for both the PET and PC substrate; however, the maximum principal stresses of three different AR coatings were tensors for the PET substrate, and compressive for the PC substrate. The principal stresses recorded were -916 MPa (Nb 2 O 5 /SiO 2)2 > 438 MPa (Ta 2 O 5 /SiO 2)2 > 346 MPa (TiO 2 /SiO 2)2 for PET, and -951 MPa (Nb 2 O 5 /SiO 2)2 > -838 MPa (Ta 2 O 5 /SiO 2)2 > -766 MPa (TiO 2 /SiO 2)2 for PC. The different elasticity moduli (ΔE) and relative elasticity between the different film layers may potentially be used to mitigate stress relief in multilayer coatings. [ABSTRACT FROM AUTHOR]

Silicon oxide films were deposited on glass and polyethylene terephthalate (PET) substrates by means of radio-frequency (RF) magnetron sputtering and the effects of the RF power on the microstructure, morphology, composition and wetting property of the films were investigated and compared. It was found that the films on PET have more voids and fissures than those on glass, especially those deposited with a RF power lower than 200 W, while the films on glass are all compact. All films possess the columnar structure and columns in the films on PET are coarser. These differences are supposed to result from the slower nucleation and faster diffusion on PET. Higher RF power provides particles with higher kinetic energy and produces films with denser structure and coarser columns. The silicon oxide films on both kinds of substrate have comparable thicknesses and compositions with an O/Si atomic ratio of 1.5. The surface roughness of the films is contributed from the roughness of substrate and the true roughness of films and the true roughness of films on both kinds of substrates reaches minimum at 200 W. The contact angle of water on the films shows a similar tendency, while the contact angle on PET is found lower than that on glass. The mechanism which explains the void formation of the film on PET can rationalize the difference. [ABSTRACT FROM AUTHOR]

Al and Ga co-doped ZnO (AGZO) semiconductor thin films were deposited on polyethylene terephthalate (PET) substrates by radio frequency magnetron sputtering. Prior to oxide thin film deposition, the hydrophilicity of the surface of the PET substrate was increased by corona discharge treatment. In this study, the influence of corona discharge power on the surface properties of the PET substrates and the effect of substrate temperature on the physical properties of PET/AGZO thin film samples were investigated. After corona discharge treatment to modify the surfaces of the PET substrates, drastic decreases in the contact angle of water on the PET substrates demonstrated that the corona discharge treatment changed the surface wettability of the PET substrates. Experimental results showed that increasing the substrate temperature from room temperature to 135 °C significantly enhanced the crystallinity, reduced the surface roughness, and improved the electrical properties of the AGZO thin films. The AGZO thin films deposited on PET substrates at 135 °C had the highest Hall mobility of 5.5 cm 2 /Vs. [ABSTRACT FROM AUTHOR]

An investigation has been taken on enhancing lithium electrochromic performances of mixed organotungsten oxide (WO y C z )/organotitanium oxide (TiO y C z ) films, co-synthesized onto 60 Ω/square flexible polyethylene terephthalate (PET)/indium tin oxide (ITO) substrates by a low temperature plasma polymerization method at various mixed concentrations of precursors tungsten hexacarbonyl W(CO) 6 and titanium n-butoxide Ti(C 4 H 9 O) 4 . The plasma polymerized-organo‑tungsten‑titanium oxides (WTi x O y C z ) films possess notable electrochromic performances while switch tested by a potential sweep from −1 V to 1 V at a scan rate of 50 mV/s and from 1 V to −1 V at a scan rate of −50 mV/s for 200 cycles of reversible Li + ion intercalation and de-intercalation in a 1 M LiClO 4 -PC electrolyte, still after bended 360 o around a 2.5 cm diameter rod for 1000 cycles. Optical modulation (Δ T ) of 74.8% for WO y C z films at a wavelength of 850 nm is appreciably progressed of up to 82.7% for WTi x O y C z films as co-deposited by a low temperature plasma polymerization method. [ABSTRACT FROM AUTHOR]

Twisting monotonic and fatigue experiments were conducted on multi-layered films of Ag-alloy based indium tin oxide (ITO) deposited on polyethylene terephthalate (PET). In the twisting tests, crack development and electrical resistance were monitored in situ . Cracks initiated at an angle of 39° ± 1.7° and propagated towards the direction of the sample length. Two sets of experiments were performed; the first set of experiments was conducted to study the effect of twisting angle and temperature on the film's electromechanical performance. The other set of experiments was conducted to study the effect of temperature in the absence of cyclic twisting deformation. The change in electrical resistance increased with number of twisting cycles and twisting angle. In addition, the highest change in electrical resistance was observed for samples subjected to cyclic fatigue at 100 °C, which is attributed to crack growth and oxidation of the Ag-alloy layer. The cracks were observed to initiate not only from coating defects but also from edge defects. Development of cracks is accelerated due to the combined effects of the external repeated stress and temperature. Therefore, it is suggested that controlling temperature when using ITO/Ag-alloy/ITO thin film under mechanical stress is important for electrical device performance; temperatures in both fabrication and use should not exceed 50 °C. [ABSTRACT FROM AUTHOR]

• Inorganic-organic composite thin film was fabricated by spray coating. • Photodetecting properties indicates an n-p heterojunction formation. • The film shows linear sensitivity and rapid response for ethanol at room temperature. Hybrid thin film sensors based on semiconductor oxides and carbon nanostructures are promising materials to improve the sensing, thermomechanical and optical properties. In this study, a thin film based on a composite from ZnO nanoparticles, milled multiwalled carbon nanotubes, and conducting polymer was fabricated. The layer was spray-coated to the surface of amorphous polyethylene terephthalate substrate. The hybrid layer and components have been systematically characterized by transmission and scanning electron microscopy, dynamic light scattering and the optical absorption spectrum was observed by ultraviolet-visible spectroscopy. The change in glass transition temperature was measured by dynamic mechanical analysis. Gas sensing tests reveal that the ZnO/multiwalled carbon nanotube/ poly(3,4-ethylenedioxythiophene): polystyrene sulfonate film on amorphous polyethylene terephthalate has remarkably enhanced performance compared to the same layer on indium tin oxide /polyethylene terephthalate. It could detect ethanol vapor in a wide concentration range with good response, fast recovery, and repeatability at room temperature. The layer was also tested as an ultraviolet photodetector, showing a promising signal. These features indicate the composite usability in further sensor applications. [ABSTRACT FROM AUTHOR]

We herein report our investigation into the effect of plasma-induced surface modification of a polyethylene terephthalate (PET) surface on the output performance of a triboelectric generator (TEG). The PET surface was subjected to plasma treatment using a CF 4 /CH 4 /Ar gas mixture (25–75% CF 4 ) to increase the surface roughness and triboelectric charge density. Plasma diagnostics were then performed using optical emission spectroscopy and a double Langmuir probe, while analysis of the surface roughness and surface characteristics was performed using atomic force microscopy and X-ray photoelectron spectroscopy, respectively. Following plasma treatment, we prepared a triboelectric energy harvester device, and demonstrated an outstanding improvement in TEG short-circuit current measurements. [ABSTRACT FROM AUTHOR]

Tungsten oxide (WO 3 ) thin films were deposited onto flexible substrates using radio frequency magnetron sputtering for high electrochromic performance purposes. The effects of both non-aqueous electrolytes (lithium perchlorate (LiClO 4 ), lithium trifluoromethanesulfonate (LiTRIF)) and the electrochromic thickness layers on the electrochromic properties of flexible tungsten oxide films were investigated. The deposited film characteristics were measured using cyclic voltammetry, scanning electron microscopy and X-ray diffraction. The electrochromic device characteristics such as electrochromic contrast, coloration efficiency, and switching time were determined as a function of the WO 3 film thicknesses. Fast switching times (bleaching time (t b ): 5.88 s; coloration time (t c ):1.6 s) were obtained for the electrochromic device with a 465-nm WO 3 film. Reversibility and switching time properties of WO 3 film (465 nm) were compared to LiClO 4 and LiTRIF liquid electrolyte media. Higher reversibility of 82% and better current density of 3 mA/cm 2 were obtained for a WO 3 film-containing device in LiTRIF electrolyte solution. [ABSTRACT FROM AUTHOR]

Hydrophilic/hydrophobic polymer composite membranes have known a growth of interest in various separation processes, such as desalination of water, pervaporation, reverse osmosis, gas separation, micro- and nanofiltration. In this work we obtained porous hydrophilic/hydrophobic composite membranes by RF magnetron sputtering deposition of polytetrafluoroethylene-like (PTFE) thin films on one side of a polyethylene terephthalate (PET) track etched membrane, used as a porous substrate. The results show that the obtained PTFE material containing various CF x bonds is present both on the membrane surface and in its pores as a thin film, without completely covering of the pores in-depth. We proved that the membrane presents one hydrophilic side (PET) and one hydrophobic side (PTFE), with flowing characteristics (tested for gas) maintained even in the situation when the pores seems completely covered with PTFE material on the surface. [ABSTRACT FROM AUTHOR]

A simple method was developed to increase the electrical conductivity of Ag nanowire (NW) transparent electrodes prepared at room temperature. By dipping Ag NW coated poly(ethylene terephthalate) (PET) film into AgBr solution with sodium ascorbate as reductant, Ag nanoparticles grow on the surface of Ag NWs and their junction positions. It was found that the attachment of Ag nanoparticles on Ag NWs decreases the electrode film resistance from 220– 300 Ω/sq. to 30– 50 Ω/sq., which is mainly due to the change in junction resistance with Ag nanoparticles functioning as a bridge for electron transportation between Ag NWs. Ag NW coated PET films have a transmittance of 85.0% at the spectral wavelength of 550 nm, and this value does not change much after AgBr treatment. A mechanical study shows that Ag NW electrodes on flexible substrates have excellent robustness subjected to bending. The properties of transparent Ag NW electrodes prepared using our method meet the requirements of transparent electrodes for many applications and could be a replacement for indium tin oxide for flexible electronics and solar cells. [ABSTRACT FROM AUTHOR]

• Resistive switching characteristics of conducting polymer PEDOT:PSS films were investigated. • Reduction-oxidation of PEDOT:PSS film are considered as possible switching mechanism. • Flexible memory devices prepared on ITO-covered PET based on PEDOT:PSS film. • No performance degradation after bending the devices from 70°−180° angles. In this work, the resistive switching memory has been investigated in conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS) with aluminium (Al) and indium tin oxide (ITO) acting as electrodes. Current-voltage (I-V) characteristics of the fabricated Al/PEDOT:PSS/ITO flexible Polyethylene terephthalate substrate device reveal a non-volatile resistive switching behaviour. The memory device demonstrates resistive switching non-volatile memory with I ON /I OFF current ratio between the high resistance state (HRS) and low resistance state (LRS) up to 104. Both the HRS and LRS of the memory devices are stable, showing no significant change in value of I ON /I OFF current ratio, which is maintained at 104 in magnitude under continuous read-out testing for 100 cycles at 90º bending angle, and also retention time of 33 min that confirms the device durability and non-volatility. The charge transport mechanism of the fabricated non-volatile organic devices is governed by space-charge limited conduction. It is proposed that the reduction and oxidation of PEDOT:PSS film might be the switching mechanism. Interestingly, the performance of the memory device revealed no detectable degradation and remained identical even after bending the device from 70 to 160° angles, representing excellent flexibility. Besides, the lowest power and the critical compliant current for resistive switching are determined. The power density for 180° (without bending), 160°, 90° and 70° bending angles is ∼ 30 Wm−2. It demonstrates that for a small range of compliance current, our device showed more power capacity with lower voltage consumption, which makes it a potential candidate for low power consumption flexible non-volatile memory devices. [ABSTRACT FROM AUTHOR]

• Water vapor transmission rate (WVTR) of inorganic layers on polymer is calculated. • Effects of amorphous/polycrystalline structures on barrier property are evaluated. • Al 2 O 3 /ZnO film on polymer has a better barrier performance than that of ZnO/Al 2 O 3. • The effect of inorganic layer thickness can be ignored if it excesses 100 nm. • The relative error between calculated and measured WVTR is less than 10%. The barrier performance of amorphous and/or polycrystalline inorganic oxide thin films deposited on flexible polyethylene terephthalate (PET) substrates is evaluated by a developed model that accounts for the diffusion of water vapor through the pinholes and grain boundaries, respectively, in amorphous and polycrystalline sublayers. Three-dimensional diffusion simulations are performed for modeling the influences of layer thickness, defect spacing and grain size on the barrier properties of single (multi) layer films. The water vapor transmission rate (WVTR) is calculated for single/multi-inorganic layers with different structures (amorphous and polycrystalline), numbers of inorganic layers and thicknesses. The simulation results show that the WVTR decreases exponentially with the increase of the inorganic layer thickness. According to the fitted results, the diffusion coefficient of water vapor in the defects (grain boundaries or pinholes) of inorganic materials is much smaller than that in PET, and the diffusion coefficient of water vapor in the grain boundaries of the polycrystalline inorganic layer (PIL) is close to that in the defects/pinholes of the amorphous inorganic layer (AIL). In comparison to PET/AIL, PET/PIL and PET/PIL/AIL films, the barrier performance of PET/AIL/PIL film is superior. As examples, PET/Al 2 O 3 /ZnO and PET/ZnO/Al 2 O 3 films were prepared for verification of the developed model. The simulated WVTR values agree well with the experimental ones. [ABSTRACT FROM AUTHOR]

The strain-resistance transduction of commercially available In 2 O 3 /Au/Ag layered films supported by polyethylene terephthalate (PET) foil was studied. A colossal gauge factor as high as about 60,000 was observed upon a strain of 1%. Such ultra-high response is presumably owing to conductivity derived from the tunnelling current across cracks formed in the strained In 2 O 3 film; the cracks – as visualized by scanning electron microscopy – are oriented perpendicularly to the strain vector and are noted for their uniform width across the sample. It is further demonstrated that the standardly defined gauge factor is incommensurate for strain sensors with transduction based on the tunnelling current and a redefined formula for the gauge factor was proposed. [ABSTRACT FROM AUTHOR]

Thickness-dependent electrical, structural, and optical properties of zinc oxide (ZnO) thin films on polyethylene terephthalate (PET) substrates have been investigated in the very thin thickness range of 20 to 120 nm. In this thickness range, the electrical resistance of ZnO film increased with an increase in film thickness. This unusual transition behavior was explained in terms of structural evolution from Zn-phase-incorporating non-crystalline ZnO to hexagonal-structured ZnO. A critical thickness for the full development of hexagonal ZnO crystal was estimated at approximately 80 nm in this study. ZnO thin films on PET substrates exhibit a high optical transmittance of > 70% and good endurance to bending cycles over the measured thickness range. The results of this study indicate that a trade-off should be sought between structural, electrical, optical, and mechanical properties for practical applications of very thin ZnO films on organic substrates. [ABSTRACT FROM AUTHOR]

Aluminum doped ZnO (AZO) and pure ZnO thin films are grown on polymer substrates by pulsed-laser deposition and the optical, electrical, and structural film properties are investigated. Laser fluence, substrate temperature, and oxygen pressure are varied to obtain transparent, conductive, and stoichiometric AZO layers on polyethylene terephthalate (PET) that are free of cracks. At low fluence (1 J/cm 2 ) and low pressure (10 − 3 mbar), AZO/PET samples of high optical transmission in the visible range, low electrical sheet resistance, and high figure of merit (FOM) are produced. AZO films on fluorinated ethylene propylene have low FOM. The AZO films on PET substrates are used as electron transport layer in inverted organic solar cell devices employing P3HT:PCBM as photovoltaic polymer-fullerene bulk heterojunction. [ABSTRACT FROM AUTHOR]

Nanostructure formation was explored for various carbon-based materials, such as diamond, carbon fiber, polyethylene terephthalate and poly (methyl methacrylate), which have different levels of crystallinity, ranging from perfect crystal to polymeric amorphous. After treatment of oxygen plasma glow discharge, the nanostructures on these carbon-based materials were found to evolve via preferential etching due to the co-deposition of metal elements sputtered from the metal cathode plate. Local islands or clusters formed by the metal co-deposition have a low etching rate compared to pristine regions on each material, resulting in anisotropic patterns on the carbon-based materials. This pattern formation mechanism was confirmed by covering the cathode or preventing the co-deposition of metallic sources with a polymeric material. Regardless of the level of crystallinity of the carbon-based materials, no patterns were observed on the surfaces covered with the polymeric material, and the surfaces were uniformly etched. It was found that the materials with low crystallinity had a high etching rate due to low carbon atom density, which thus easily formed high-aspect-ratio nanostructures for the same plasma treatment duration. [ABSTRACT FROM AUTHOR]

In this study, polyethylene naphthalate (PEN) was investigated as a flexible substrate because, compared with polyethylene terephthalate, it achieves a lower root mean square roughness and transmittance, which is favorable for reducing leakage from the bottom of flexible substrates. A flexible device structure composed of tungsten oxide/indium-doped tin oxide/PEN was used in an electrochromic (EC) test. The experimental results show that the flexible EC display device achieved a high transmittance difference of > 40% and color efficiency of 70.2 cm 2 /C at 560 nm. The transmittance difference was degraded in the visible range after 200 cycles of continuous bending. Furthermore, compared with flat fresh devices, the WO 3 device exhibited poor retention properties in a colored state after being subjected to longer bending cycles. [ABSTRACT FROM AUTHOR]

In this work SiN x thin films have been deposited by Hot-Wire Chemical Vapor Deposition (HW-CVD) technique to be used as encapsulation barriers for flexible organic electronic devices fabricated on polyethylene terephthalate (PET) substrates. First results of SiN x multilayers stacked and stacks of SiN x single-layers (50 nm each) separated by an Ar-plasma surface treatment are reported. The encapsulation barrier properties of these different multilayers are assessed using the electrical calcium degradation test by monitoring changes in the electrical conductance of encapsulated Ca sensors with time. The water vapor transmission rate is found to be slightly minimized (7 × 10 − 3 g/m 2 day) for stacked SiN x single-layers exposed to argon plasma treatment during a short time (2 min) as compared to that for stacked SiN x single-layers without Ar plasma treatment. [ABSTRACT FROM AUTHOR]

• F-doped SnO 2 (FTO) film was deposited on polymer substrate by sputtering. • Effect of O 2 flux and substrate temperature on characteristics of film was studied. • Highly transparent conductive FTO film can be obtained by controlling O 2 flux. • The damp-heat stability and bending properties of FTO film were investigated. F-doped SnO 2 (FTO) films have excellent optical-electrical properties and have been widely used, but the preparation of FTO film on the surface of flexible polymer substrate by magnetron sputtering has not been reported. In this study, Sn-SnF 2 mixture was used as the target, and then the FTO film was prepared by reactive magnetron sputtering on the surface of the polyethylene terephthalate substrate at substrate temperature of room temperature, 60 and 100 °C. The results show that highly transparent conductive FTO films can be obtained by optimizing the O 2 flow rate at each substrate temperature. In general, as the substrate temperature increases, the optimized range of O 2 flow rate shifts to the direction of lower O 2 flow rate and the corresponding transparent conductive properties are slightly enhanced. Currently, the films show sheet resistance of 209–423 Ω/sq., transmittance in visible-light range of 84.4–90.3% and figure of merit of 5.09–12.9 × 10–4 Ω–1, which is comparable with those of previously reported SnO 2 -based films. At the same time, the films have better bending performance at the bending radius of 20 mm, but they have poor damp-heat stability. In addition, the influence of substrate temperature and O 2 flow rate on structure (thickness, crystallinity and surface roughness) and energy gap of the films is also investigated. [ABSTRACT FROM AUTHOR]

• Heating characteristics of silver nanowire and conducting polymer. • Heating temperature of the film increases proportionally with DC voltage applied. • The stacking order of the layered film affects on the film durability. Application of conductive coating solutions for transparent heating film has been actively researched and developed on academia and industry. In this work, transparent heating films were fabricated using the conductive coating solutions of silver nanowires and poly(p-phenylene vinylene) as a conducting polymer, and the heating characteristics was investigated on these films deposited on transparent substrates made of polyethylene terephthalate. The transparent heating films were prepared by changing the stacking order and the number of layers of silver nanowire and conducting polymer, and the structure and characteristics of the films were analyzed. The electrical resistance and the light transmittance decreased linearly with the stacking number of a film. The heating temperature of transparent heating film increased proportionally with DC voltage applied, regardless of the stacking order. Furthermore, it was found that bending durability of transparent heating films was significantly influenced by the stacking order of the film. [ABSTRACT FROM AUTHOR]

In this study, we develop a low-cost method for transferring a large-scale graphene film onto a flexible transparent substrate. An easily accessible method for home-made chemical vapor deposition (CVD) and a commercial photograph laminator were utilized to fabricate the low-cost graphene-based transparent conductive flexible substrate. The graphene was developed based on CVD growth on nickel foil using a carbon gas source, and the graphene thin film was easily transferred onto the laminating film via a heated photograph laminator. Field emission scanning electron microscopy and atomic force microscopy were utilized to examine the morphological characteristics of the graphene surface. Raman spectroscopy and transmission electron microscopy were utilized to examine the microstructure of the graphene. The optical–electronic properties of the transferred graphene flexible thin film were measured by ultraviolet–visible spectrometry and a four-point probe. The advantage of this method is that large-scale graphene-based thin films can be easily obtained. We provide an economical method for fabricating a graphene-based transparent conductive flexible substrate. [ABSTRACT FROM AUTHOR]

In this study, a pulsed-mode electrochemical deposition (Pulse-ECD) technique was employed to deposit platinum nanoparticles (PtNPs) on the indium tin oxide/polyethylene terephthalate (ITO/PET) substrate as a flexible counter electrode for dye-sensitized solar cells (DSSCs). The characteristic properties of the Pulse-ECD PtNPs were prepared and compared to the traditional (electron beam) Pt film. The surface morphologies of the PtNPs were examined by field emission scanning electron microscopy (FE-SEM) and the atomic force microscope (AFM). The FE-SEM results showed that our PtNPs were deposited uniformly on the ITO/PET flexible substrates via the Pulse-ECD technique. The AFM results indicated that the surface roughness of the pulsed PtNPs influenced the power conversion efficiency (PCE) of DSSCs, due to the high specific surface area of PtNPs which enhanced the catalytic activities for the reduction (I 3 − to I − ) of redox electrolyte. In combination with a N719 dye-sensitized TiO 2 working electrode and an iodine-based electrolyte, the DSSCs with the PtNPs flexible counter electrode showed a PCE of 4.3% under the illumination of AM 1.5 (100 mW cm − 2 ). The results demonstrated that the Pulse-ECD PtNPs are good candidate for flexible DSSCs. [ABSTRACT FROM AUTHOR]

The SiO 2 /polyethyleneimine (PEI) films with structural colors on poly(ethylene terephthalate) (PET) substrates were fabricated by an electrostatic self-assembly method. The morphology of the films was characterized by Scanning Electron Microscopy. The results showed that there was no distinguishable multilayered structure found of SiO 2 /PEI films. The optical behaviors of the films were investigated through the color photos captured by a digital camera and the color measurement by a multi-angle spectrophotometer. Different hue and brightness were observed at various viewing angles. The structural colors were dependent on the SiO 2 particle size and the number of assembly cycles. The mechanism of the structural colors generated from the assembled films was elucidated. The morphological structures and the optical properties proved that the SiO 2 /PEI film fabricated on PET substrate formed a homogeneous inorganic/organic SiO 2 /PEI composite layer, and the structural colors were originated from single thin film interference. [ABSTRACT FROM AUTHOR]

In this paper, we report the performance improvement of inverted organic solar cells by adding an ultrathin electron selective layer of Al 2 O 3 prepared between the indium tin oxide (ITO) electrode and the active transport layer through atomic layer deposition (ALD). We evaluated the cell shelf-life after encapsulating with SiO x -coated polyethylene terephthalate, where the SiO x layer was made by plasma enhanced chemical vapor deposition (PECVD). It was found that the devices with ALD Al 2 O 3 have a higher open circuit voltage than those without the ALD Al 2 O 3 layer. Al 2 O 3 deposited on an ITO electrode decreased the work function of ITO. Furthermore, based on the current density–voltage curves of the initial devices showing a pronounced S-shape, we soaked the cells with the ultraviolet (UV) light process. Then we obtained a higher efficiency in these ALD Al 2 O 3 treated devices. With a careful analysis by atomic force microscopic and X-ray photoelectron spectroscopy, we believe that the UV light soaking process affected both ITO and Al 2 O 3 . Further, after the encapsulation by PECVD SiO x , our devices achieved a shelf-life of over 500 h for 50% retained cell efficiency. [ABSTRACT FROM AUTHOR]

Abstract: Effects of the annealing temperature on mechanical durability of indium-tin oxide (ITO) thin films deposited on polyethylene terephthalate (PET) substrates were investigated. The ITO films were annealed at the range from 150°C to 195°C after the DC sputtering deposition for the production of polycrystalline ITO layers on the substrates. The onset strains of cracking in the annealed ITO films were evaluated by the uniaxial stretching tests with electrical resistance measurements during film stretching. The results indicate that the onset strain of cracking in the ITO film is clearly increased by increasing the annealing temperature. The in-situ measurements of the inter-planer spacing of the (222) plane in the crystalline ITO films during film stretching by using synchrotron radiation strongly suggest that the large compressive stress in the ITO film increases the onset strain of cracking in the film. X-ray stress analyses of the annealed ITO films and thermal mechanical analyses of the PET substrates also clarifies that the residual compressive stress in the ITO film is enhanced with increasing the annealing temperature due to the considerably larger shrinkage of the PET substrate. [Copyright &y& Elsevier]

Abstract: Indium tin oxide (ITO) thin films were deposited on polyethylene terephthalate substrates using a DC facing target sputtering (DC-FTS) system at room temperature. The sputtering conditions including oxygen partial pressure and discharge current were varied from 0% to 4% and 0.5A to 1.3A, respectively. X-ray diffraction and scanning electron microscopy were used to study the structure and surface morphology of as-prepared films. All the films exhibited amorphous structures and smooth surfaces. The dependence of electrical and optical properties on various deposition parameters was investigated by a linear array four-point probe, Hall-effect measurements, and ultraviolet/visible spectrophotometry. A lowest sheet resistance of 17.4Ω/square, a lowest resistivity of 3.61×10−4 Ωcm, and an average relative transmittance over 88% in the visible range were obtained under the optimal deposition conditions. The relationship between the Hall mobility (μ) and carrier concentration (n) was interpreted by a functional relation of μ~n−0.127, which indicated that ionized donor scattering was the dominant electron scattering mechanism. It is also confirmed that the carrier concentration in ITO films prepared by the DC-FTS system is mainly controlled by the number of activated Sn donors rather than oxygen vacancies. [Copyright &y& Elsevier]

Abstract: Substantial recovery (decrease) of electrical resistance during and after unloading is demonstrated for copper films on polyethylene terephthalate substrates subjected to a tensile strain with different peak values. Particularly, the films strained to 5% exhibit full resistance recovery after unloading despite clearly visible plastic deformation of the film. The recovery of electrical resistance in connection with the mechanical behavior of film/substrate couple is discussed with the help of in situ scanning electron microscopy and X-ray diffraction analysis. [Copyright &y& Elsevier]

Abstract: Open spaces in polyethylene terephthalate (PET) coated with aluminum silicate (Al x Si1− x O y ) were probed using monoenergetic positron beams. The energy distributions of the annihilation γ rays and the positron lifetime spectra were measured for 60-nm-thick Al x Si1− x O y (x =0–1) deposited on PET using electron-beam evaporation. A clear correlation was obtained between the line-shape S parameter of the annihilation γ rays, water vapor, and oxygen transmission rates. The results suggest that open spaces in the Al x Si1− x O y layers play an important role in water/oxygen diffusion in Al x Si1− x O y /PET, where the concentration/size of such spaces showed its minimum value at x =0.2–0.3. The free volume fraction below the interface between Al x Si1− x Oy and PET (region width=100–400nm) was decreased by the deposition of the coating layer, and this region was also considered to act as a barrier against penetrations of gasses and molecules. [Copyright &y& Elsevier]

• Hybrid film heater made of Ag nanoparticles (NPs) and double-walled carbon nanotubes. • AgNPs were prepared from Ag wires using a facile spark-depositing technique. • Hybrid film heater reaches the maximum temperature of 118.6 °C at 8 V. A hybrid flexible and transparent heater based on double-walled carbon nanotubes (DWCNTs) and silver nanoparticles (AgNPs) is fabricated on a polyethylene terephthalate substrate via facile spray-coating and spark-depositing techniques, respectively. The AgNPs are simply prepared by electrically sparking pure Ag wires in ambient environment with no vacuum system required. The optical, electrical and electrothermal properties of the hybrid AgNP/DWCNT and simple DWCNT film devices are investigated. The results show that the hybrid film heaters exhibit superior electrothermal performances to the DWCNT film heaters, as having higher maximum temperatures at the same applied voltages, as well as faster thermal heating and cooling responses. The simple DWCNT heater with optical transmittance of 72.7% at a wavelength of 550 nm reaches the maximum temperature of 95.0 °C, whereas the hybrid AgNP/DWCNT heater with optical transmittance of 64.0% reaches higher maximum temperature of 118.6 °C, as electrically supplied at 8 V. Furthermore, the mechanical flexibility of the hybrid and DWCNT film heaters is studied with different folding directions, and a little deviation in their electronic conduction is observed, while still performing good heating temperature after a bending test. This simple hybrid film heater demonstrates the efficient electrothermal performances, which can be utilized as a flexible and transparent heating device in various practical applications. [ABSTRACT FROM AUTHOR]

• High-power impulse magnetron sputter deposited ZnO/Ag/ZnO on flexible substrate. • Effects of layer thickness and metal type on the photoelectric properties addressed. • ZnO/Ag/ZnO showing excellent 7.2 Ω.sq−1 and 87.7% transmittance demonstrated. • Superior sheet resistance retained after 3000 bending cycles. A transparent conductive material, mostly transparent conductive oxide (TCO), is essential and indispensable for flexible electronics. Different from the conventional, single-layered TCO, multilayered oxide/metal/oxide (OMO) structures have been investigated as a promising alternative. The metal layer serves to reduce the electrical resistance of the oxides and the transparency is enhanced by suppressing the reflection from middle metal layer and substrate. Meanwhile, due to the limited temperature tolerance of the flexible polymeric substances, high-power impulse magnetron sputtering technique has been used to deposit the OMO structures at a substrate temperature lower than 70 °C. Two different OMO multilayered structures, including ZnO/Ag/ZnO and ZnO/Cu/ZnO, are deposited on polyethylene naphthalate (PEN) and polyethylene terephthalate (PET), and soda lime glass. The effects of layer thickness and metal type on the transmission and resistivity of the obtained OMO structures are investigated. The correlation between OMO structure characteristics and the resulting photoelectric properties are also studied. A 35-nm ZnO/20-nm Ag/30-nm ZnO having excellent resistivity of 6.2 × 10−5 Ωcm (7.2 Ωsq−1) and transmittance of 87.7% is demonstrated. Furthermore, after 3000 bending cycles, the multilayered OMOs on PET and PEN retain their superior electrical properties, exhibiting resistivity of 3.8 × 10−4 and 1.3 × 10−4 Ωcm, respectively. [ABSTRACT FROM AUTHOR]

A flexible thin-film encapsulation architecture for organic electronics was built and consisted of a silicon oxide/alumina and parylene layer deposited over Ca sensors on a barrier-coated polyethylene terephthalate substrate. The film's effective water vapor transmission rate was 2.4±1.5×10−5 g/m2/day at 20°C and 50% relative humidity. Flexural tests revealed that for films deposited on the polyethylene terephthalate substrate, the barrier layer failed due to cracking at a curvature radius of 6.4mm, corresponding to a strain of 0.8%. Adding an epoxy top coat of suitable thickness shifted the neutral axis toward the encapsulation layer, reducing the induced strain. Barrier performance was maintained under the 6.4mm radius of curvature in this encapsulation structure. Thus, shifting the neutral axis via device structural design is an effective method of extending the flexibility of thin-film encapsulation structure without compromising the performance loss as a barrier layer. [ABSTRACT FROM AUTHOR]

Abstract: We prepared cadmium sulfide (CdS) films on a polyethylene terephthalate (PET) substrate by a chemical bath deposition (CBD) technique. To improve the adhesion between the CdS film and the PET substrate, the substrate was pre-treated with an O2 plasma by an inductively coupled plasma. The surface characterizations of the pre-treated PET substrate were analyzed by a contact angle measurement and atomic force microscopy. The results showed that that O2 plasma-treated PET films had more hydrophilic surface. The hydrophilic property of the substrate is one of the important factors when a film is prepared by CBD. The structural and the optical properties of the CdS films, deposited on PET substrates, were analyzed by using a scanning electron microscope, X-ray diffraction and a UV–visible spectrophotometer. The CdS films were formed on a compact and granular structure. The optical transmittance was also improved. Therefore, the O2 plasma treatment of a PET surface is an effective method of preparing CdS films deposited on substrates by CBD. [Copyright &y& Elsevier]

Abstract: The tin indium oxide (ITO) films were deposited onto the polyethylene terephthalate (PET) surface that has been bombarded by an O ion beam. The variation of the O bombardment time resulted in the production of ITO/PET complex with different properties. Characterization by four-point probe measurement after the bending fatigue test showed that the adhesion property of the ITO/PET complex could be improved by the increase of O bombardment time while little change of electrical resistivity was observed. Scanning electron microscopy results showed that after the bending fatigue test, the nano scale seams and micro scale trenches appeared at the surface of the ITO/PET complex. The former was only the cracks of ITO film, which has little influence on the continuity and electrical resistivity of ITO film. On the contrary, the micro scale trenches were caused by the peeling off of ITO chips at the cracks, which mainly influenced the continuity and electrical resistivity of ITO film. With the increase of O bombardment time, the number and length of the micro scale trenches decreased. X-ray photoelectron spectrometry characterization showed that with the increase of O bombardment time, parts of the methylene C bonds were transformed into C O bonds, which could be broken to form C O In(Sn) bonds at the initial stage of ITO film growth. By these C O In(Sn) crosslink bonds, the ITO film could adhere well onto the PET and the ITO/PET complex display better anti-bending fatigue property. Finally, in the context of the application of the ITO/PET complex as a flexible electrode substrate, the present work reveals a simple way to crosslink them, as well as the physicochemical mechanism happening at the interface of complex. [Copyright &y& Elsevier]