Transparent Conductive Thin Films Research Articles

Robust ZTO-reinforced Ag nanowire hybrid transparent conductive thin films with absorption-enhanced electromagnetic interference shielding property

Technological advances have accelerated the pursuit of transparent conducting thin films (TCFs) with superior mechanical properties, durability, efficient optoelectrical performance and substrate compatibility as a pivotal focus in the realm of flexible transparent electronics. Against this background, this work investigates the fabrication of multilayer silver nanowire (AgNW) thin films reinforced by zinc tin oxide (ZTO) thin film encapsulation on polycarbonate substrates by a combination of sputtering and spin-coating techniques. An investigation of the influence of AgNW percolation networks on the optoelectrical properties of ZTO/AgNW/ZTO hybrid thin films was carried out. The impact of ZTO protective layers on the enhancement of electrical properties, adhesivity, flexibility and environmental stability of the multilayer TCF was elucidated. Additionally, to explore the compatibility of the fabricated TCF in integrated device and stealth applications, its electromagnetic interference shielding properties were investigated. The hybrid TCF showed 99.47% EMI shielding efficiency with an absorption-dominant EMI shielding effectiveness of 22.7 dB in the x-band region.

Investigation on preparation and performance of high-reliable ZnO–NiO@Cu NW flexible transparent conductive thin films

Investigation on preparation and performance of high-reliable ZnO–NiO@Cu NW flexible transparent conductive thin films

High transparent conductive Ga-doped ZnO-based multilayer thin films with embedded ultrathin TiN layer deposited in oxygen-containing atmosphere.

To avoid metal layer oxidation during the deposition of transparent conductive oxide (TCO)/metal/TCO multilayer films in an oxygen-containing atmosphere, the ultra-thin (<10 nm) titanium nitride (TiN) layer has been proposed to replace metal embedding in gallium-doped zinc oxide (GZO) film for the development of indium-free transparent electrodes. The effects of TiN thickness on the structure, morphology, electrical, and optical properties of GZO/TiN/GZO multilayer thin films deposited in argon-oxygen mixtures on glass substrates by magnetron sputtering are investigated. The experimental results reveal that multilayers with the 8 nm-thick TiN layer have the optimal performance (figure of merit of 2.75 × 10-1 Ω-1): resistivity of 4.68 × 10-5 Ω cm, and optical transmittance of above 91% in the visible region, which is superior to the sandwich film with the metal embedded layer.

Preparation and photoaging resistance of single-walled carbon nanotubes transparent conductive thin films for electrostatic dust removal of photovoltaic panels

A single-walled carbon nanotubes transparent conductive film for electrostatic dust removal of photovoltaic panels was prepared by a rod coating method and subjected to xenon lamp aging experiments at different irradiance (300 W/m2, 150 W/m2, 50 W/m2, 2000 h) to investigate the photoaging resistance of the film. After aging, the light transmittance decreased from 91.34% to a minimum of 90.39%, the sheet resistance increased from 0.325 * 105 Ω/□ to a maximum of 4.753 * 105 Ω/□, the surface energy decreased, and the adhesive strength of the film at an irradiance of 300 W/m2 decreased from a class 5B to a class 4B. The film was used as the surface material of photovoltaic panels and was subjected to electrostatic dust removal experiments, which showed that the final dust removal rate of different aging types of films was between 97.5% and 98.5%, the power generation efficiency of photovoltaic panels can reach 93.5%− 97.8% of that of ordinary photovoltaic panels in the dust-free state on the surface, and excellent application results are achieved. The results of the study are conducive to expanding the application scenarios of single-walled carbon nanotubes transparent conductive films from indoor or air-isolated areas to outdoor ones.

Durable multicolor electrochromic fibers based on metal oxidecoated steel tapes

Electrochromic devices (ECDs) have the ability to selectively change color under the influence of electric current or potential and can keep the selected color after disconnection. They are used as smart windows, e-ink displays and even as flexible tapes. Most multicolor ECDs incorporate traditional “sandwich” architecture, which requires at least one electrode to be made of a transparent conductive polymer or thin film ceramics, and can be quite fragile and sensitive. In this paper, a flexible and durable multicolor ECD tape is reported, which uses advanced architecture, steel foil electrodes, and multiple coloration systems, for example intercalation used in tungsten and vanadium oxide based electrochromic systems, as well as a redox dye, for example methyl orange. The presented ECD tapes can utilize different metal oxides and color mechanisms with coloration efficiency around 10 cm2 C−1 for V2O5 and WO3 in both visible and IR range, and more than 30 cm2 C−1 for ZnO with added methyl orange dye. Due to the use of stainless-steel foil as a substrate, the assembled ECD tape has excellent durability properties, withstanding more than 39 MPa of pressure, and could therefore be used even in the most adverse conditions, for applications such as adaptive camouflage, color changing clothes, or other applications

The effects of RF power on the optical and electrical properties of transparent conductive Hf-doped In2O3 thin films

Highly transparent conductivity Hf-doped In2O3 (IHFO) films were prepared by RF sputtering on the glass substrate. The effects of sputtering power on the properties of transparent conductive films were studied to optimize the sputtering conditions. X-ray photoelectronic spectra (XPS) showed that the area ratio of OⅠ (oxygen vacancies) to OⅡ (lattice oxygen) achieved the highest value (0.71) at 75 W, resulting in IHFO having the lowest resistivity (2.76 × 10−4 Ω cm). However, the film prepared at 75 W has a low transmittance originating from the intense reflection caused by the high carrier concentration. In comparison, IHFO film deposited at 65 W has a lower resistivity and higher transmittance. Therefore, the IHFO film at 65 W exhibits the maximum figure of merit (FOM) value (7.04 × 10−2 Ω−1) with a low sheet resistance (4.03 Ω/sq) and a favorable average transmittance (88.16%). The p-CuI/n-IHFO diode is exhibited with high transmittance (84.25%) in the visible region and low guiding voltage (0.89 V), implying that IHFO films can be favorably used in the optoelectronic field.

Effect of preparation conditions on the properties of nano ZnO powders during ultrasonic assisted direct precipitation process.

Transparent conductive thin films (TCO) are widely used for their excellent photoelectric properties. To prepare high-quality ZnO targets, starting with the original ZnO powder is necessary. This paper aims to explore the basic technology and method of ultrasonic-assisted direct precipitation for mass production of ZnO powder and to analyze the effects of factors such as precipitating agent, surfactant, calcination temperature, and solvent on the powder's morphology, particle size, and crystallinity. The study found that the type and amount of precipitants and surfactants affect the powder's morphology and dispersibility, while calcination temperature mainly affects the powder's morphology and crystallinity. The ethanol content in the solvent mainly affects the grain size. After testing different variables, the optimal conditions for preparing spherical ZnO powder were found to be using (NH4)2·CO3 as the precipitant, adding 3% wt of PEG-400 and 3% wt of TEA at a calcination temperature of 320°C and a 60% ethanol solvent. This resulted in a smooth surface, uniform particle size distribution, good dispersibility, high crystallinity, and particle sizes between 26-32nm.

Highly stable, ultra-thin Au embedded zinc tin oxide multilayer transparent conductive thin films

Transparent conducting thin films (TCFs) with excellent stability and good mechanical properties, room temperature processing, as well as owing high transparency and conductivity, have become an essential requirement in numerous applications. Here, we report the fabrication of room temperature processed Au-embedded zinc tin oxide (ZTO) multilayer transparent conducting thin films on glass and polycarbonate substrates by radio frequency magnetron sputtering. A detailed investigation on the correlation of optical and electrical properties of the ZTO/Au/ZTO (ZGZ) multilayer thin films, with the thickness of individual layers was carried out. The ZGZ thin films showed excellent performance under various stability tests. To evaluate the commercial application capabilities in aircraft canopies and other optoelectronic devices, the fabricated ZGZ multilayer TCFs was subjected to electromagnetic interference (EMI) shielding studies. The ZGZ thin film exhibited EMI shielding effectiveness of 24.75 dB in the X-band region, yielding 99.66% power attenuation.

Microstructural and nonlinear optical properties of quaternary gallium-titanium-zinc-oxide transparent conductive semiconductor thin films

Transparent and conductive quaternary gallium-titanium-zinc-oxide films were grown on glass substrates by radio-frequency magnetron sputtering. The effects of growth temperature on structure, morphology, electrical, and nonlinear optical properties of the films were investigated systematically. All the deposited films possess hexagonal wurtzite structure with (002) preferred crystallographic orientation. The obtained optical bandgaps of the deposited films are larger than that of pure zinc oxide, which is ascribed to the reduction in band tail width. The film deposited at growth temperature of [Formula: see text]C exhibits the optimum crystalline quality with the lowest dislocation density of [Formula: see text] nm[Formula: see text], the highest visible light transparency of 82.06%, the minimum sheet resistance of 11.2 [Formula: see text]/sq, and the maximum figure-of-merit of [Formula: see text] [Formula: see text][Formula: see text]. The present findings indicate that the gallium-titanium-zinc-oxide films are promisingly utilized as transparent conductive layer. The refractive index and extinction coefficient of the deposited films were estimated by using spectrum fitting approach. A normal optical dispersion behavior was observed in visible region, while an anomalous dispersion behavior appeared in ultraviolet region. In addition, the nonlinear optical parameters were obtained. This first-hand information is useful for future rational design of multicomponent zinc oxide semiconductor materials for optoelectronic applications.

Characterization of ZnO, Ga-Doped ZnO, and Nd-Ga-Doped ZnO Thin Films Synthesized by Radiofrequency Magnetron Sputtering

Here is described the influence of deposition parameters of ZnO thin films doped with Ga and co-doped with (Ga + Nd) upon the structural, morphological, optical and electrical properties. The transparent conductive thin films were fabricated by radiofrequency (RF) magnetron sputtering using a power of 100 W and a deposition distance of 6 cm. The deposition was performed on glass substrates heated at 150 °C with a time deposition of 90 min. The influence of doping upon the structure of thin films was analyzed by x-ray diffraction (XRD). Optical transmission measurements showed an 85% transparency in the visible range for the undoped ZnO films and the transparency of these films decreased when the dopants were added. Micro-structural analysis obtained by atomic force microscopy (AFM) evidenced that the type of doping modify the microstructure of thin films. Raman and resistivity measurements emphasize the successful incorporation of dopants into the ZnO host material.

Orthogonal‐Stacking Integration of Highly Conductive Silicide Nanowire Network as Flexible and Transparent Thin Films

AbstractFlexible and transparent conductive (FTC) thin films are indispensable elements in building high‐performance flexible or soft electronics and displays. Slim inorganic nanowires (NWs), with excellent conductivity and durability, are ideal one‐dimensional ingredients to weave a quasi‐continuous FTC network. However, a precise spatial arrangement of these ultrathin NWs, to form an optimal interconnected network, represents still a difficult challenge. In this work, a catalytic growth of orderly SiNW arrays, via an in‐plane solid‐liquid‐solid mechanism, and an orthogonal‐stacking integration of the SiNWs into a 2‐layer cross‐linked network, followed by a direct alloy formation and soldering of highly conductive SiNi alloy NWs upon a flexible polyimide polymer, is demonstrated. It is also shown that the flexibility of the SiNi FTC network can be significantly enhanced with an elastic spring design of the silicide NW channels, leading to an impressive transmittance of ≈90%, a moderately equivalent sheet resistance of 130 Ω sq−1 and a durable flexibility that can sustain repetitive bending to a 2 mm radius for &gt;1000 cycles. These results highlight the unique capabilities of an optimal spatial arrangement, precise assembly/soldering and elastic geometry design of alloy NWs to enable a new generation of high‐performance FTC thin film material for future flexible electronics, displays, and bio‐interfaced sensors.

Deep UV transparent conductive Si-doped Ga2O3 thin films grown on Al2O3 substrates

β-Ga2O3 is attracting considerable attention for applications in power electronics and deep ultraviolet (DUV) optoelectronics owing to the ultra-wide bandgap of 4.85 eV and amendable n-type conductivity. In this work, we report the achievement of Si-doped β-Ga2O3 (Si:β-Ga2O3) thin films grown on vicinal α-Al2O3 (0001) substrates with high electrical conductivity and DUV transparency of promising potential as transparent electrodes. The use of Al2O3 substrates with miscut angles promotes step-flow growth mode, leading to substantial improvement of crystalline quality and electrical properties of the Si:β-Ga2O3 films. A high conductivity of 37 S·cm−1 and average DUV transparency of 85% have been achieved for 0.5% Si-doped film grown on a 6° miscut substrate. High-resolution x-ray and ultraviolet photoemission spectroscopy were further used to elucidate the surface electronic properties of the grown Si:β-Ga2O3 films. An upward surface band bending was found at the surface region of Si:β-Ga2O3 films. Interestingly, all the Si:β-Ga2O3 films have a very low work function of approximately 3.3 eV, which makes Si:β-Ga2O3 suitable materials for efficient electron injection. The present Si:β-Ga2O3 films with high conductivity, DUV transparency, and low work function would be useful as the DUV transparent electrode to develop advanced DUV optoelectronic devices.

Highly reliable MoOx/Ag NW bilayer transparent conductive thin films fabricated by all solution process and transparent heater application

The chemical instability and the decomposition of Ag nanowires (NWs) during thermal process can result in irreversible structural damage, suppressing the practical use of pure Ag NWs based transparent conductive thin films (TCTFs). In this paper, novel MoOx/Ag NW bilayer TCTFs are uniformly fabricated on glass substrates via all solution process. The electrical and optical properties of MoOx/Ag NW bilayers can be controlled by the density of the Ag NW networks. At optimal preparation conditions, MoOx/Ag NW bilayer thin films show low sheet resistance of 10.8 Ω/sq. and high optical transmittance of 85% in the visible region. The covering of MoOx layer improves the thermal stability and adhesivity of the Ag NW networks. Especially, the MoOx/Ag NW bilayer thin films are robust and able to withstand a high temperature of 300 °C in air, without deterioration of performance. The resistance does not show significant change after taping test, indicating a strong adhesion of Ag NWs to the substrate. In contrast to the degradation of pure Ag NW networks including the significant reduction of its conductivity when subjected to a series of harsh corrosion environments, the MoOx/Ag NW bilayer thin films survive structurally and retain their conductivity. Finally, the bilayer thin film is chosen to fabricate a transparent heater, which exhibits excellent heating performance. Its deicing and defogging availabilities are also shown by deicing and defogging tests.

Improvement of the uniformity of structural and electrical properties of transparent conductive Al-doped ZnO thin films by inductively coupled plasma-assisted radio frequency magnetron sputtering

Transparent conductive Al-doped Zinc oxide thin films were deposited on glass substrates by conventional radio frequency magnetron sputtering (C-RFMS) and inductively coupled plasma-assisted radio frequency magnetron sputtering (ICP-RFMS) methods. The structural and electrical properties of films were studied as a function of the radial position (r) of the substrate in both methods. A good thickness uniformity was obtained in ICP-RFMS, while a significant decrease in film thickness was observed at r=30mm (erosion zone) in C-RFMS. The c-axis orientation was achieved in all positions in ICP-RFMS, while crystallinity was degraded at r≥25mm in C-RFMS. Low resistivity ρ of the order of 10−4Ωcm was obtained at all positions in ICP-RFMS, while ρ was rapidly increased at r≥30mm in C-RFMS. In ICP-RFMS, high-energy ion bombardment is suppressed due to the modified plasma density profile and lower space potential. As for transparency, the sample prepared at r=0mm in ICP-RFMS showed an average visible transmittance of 81%, higher than that in C-RFMS. Throughout the study, it was demonstrated that ICP-RFMS method was promising to improve the radial distribution of structural, electrical, and optical properties of Al-doped ZnO thin films.

Magnetron-sputtered Mg-Ga co-doped ZnO transparent conductive thin films: Microstructural and optoelectrical investigation

The Mg–Ga co-doped ZnO (MGZO) transparent conducting thin films (TCTFs) were fabricated via magnetron-sputtering. The dependence of microstructural, morphological and optoelectrical characteristics on sputtering power was investigated. The findings demonstrate that all the TCTFs present a wurtzite hexagonal crystal structure and (002)-preferred orientation. The sputtering power has a significant impact on the properties of the TCTFs. The sample fabricated at 150 W possesses the highest optoelectrical performance and crystalline quality, with the maximum figure of merit, highest average visible transmittance, minimum resistivity, lowest dislocation density and lattice strain of 1.042×104 Ω−1·cm−1, 92.21%, 1.181×10−3 Ω·cm, 1.041×1011 cm−2 and 3.936×10−3, respectively. Moreover, the optical constants (OCs) of the MGZO TCTFs were extracted by the optical spectrum fitting method (OSFM). The dispersion behavior of refractive index (RI) was assessed. The oscillator parameters, optical bandgaps and nonlinear OCs were realized. This study provides a reference basis for the applications of MGZO TCTFs in photoelectronic devices.

Promising novel transparent conductive F-doped ZnSnO3 thin films for optoelectronic applications

Promising novel transparent conductive F-doped ZnSnO3 thin films for optoelectronic applications

Effective role of vacuum annealing in improving structural, optical, and electrical properties of SiO2/Ag/ZnO multilayers deposited by RF sputtering for optoelectronic applications

Transparent conductive thin films require multilayer coatings involving metals and dielectrics with high refractive indices. Radiofrequency (RF) magnetron sputtering technique was used to accurately fabricate the SiO2/Ag/ZnO multilayers on the corning glass substrates at 298 K to be used in Concentrating Solar Power (CSP) reflectors, solar cell, and photovoltaic applications. This method optimizes coating processes in a uniform, homogeneous manner, resulting in improved optical and electrical properties, thermal endurance, and long-term stability. The technique was used to synthesize highly translucent and conductive multilayers. The structural, optical, and electrical properties as a function of temperature in the range from 25 °C to 450 °C were detailed. The crystallite size (D cry ), lattice microstrain (ε), dislocation density (δ), and crystallites per unit surface area (N) were calculated. The values of (D cry ) increased while the other parameters decreased with increasing temperature. The linear optical parameters were calculated. The optical results demonstrated that temperature had an impact on the studied multilayers’ optical properties. The dielectric constants, the loss factor, the AC electrical conductivity, the exponential factor, and the activation energy for the dominant conductivity mechanism were all calculated using the capacitance and conductance pathways.

Shear force strategy for preparation of aligned silver nanowire transparent conductive thin films

Silver nanowires transparent conductive films (AgNWs-TCFs) prepared by traditional rotary coating method, which will cause the failure of conductive channels of AgNWs-TCFs under current load because of their AgNWs distributing randomly, were restricted its industrial application of flexible electronic devices. In this paper, the aligned AgNWs-TCFs were deposited by using the shear force from the high-speed rotating concentrated nanowire solution. Based on the rheological performance test results, the preparation conditions were set at nanowire solution of 2.0 mg/mL and the substrate immersed in PEI of 0.5 mg/mL for 10 min. The aligned AgNWs-TCFs with one-layer structure (1 L-Aligned AgNWs-TCFs) and with perpendicular two-layer structure (2 L-Aligned AgNWs-TCFs) were obtained by shear rate of 400 rpm. It was found that the resistance of 1 L-Aligned AgNWs-TCFs showed a high degree of anisotropy, with a ratio of longitudinal and lateral resistance values of 3.60, while the resistance of 2 L-Aligned AgNWs-TCFs is isotropic similarly to randomly distribution AgNWs-TCFs. However, the current-loading stability of 2 L-Aligned AgNWs-TCFs is significantly improved. The failure voltage of 2 L-Aligned AgNWs-TCFs is 13 V, but that of randomly distributed AgNWs-TCFs is only 9 V. Compared to other aligned AgNWs-TCFs preparation methods, our method enables controllable preparation and industrial development of aligned AgNWs-TCFs.

SnO2: Investigation of optical, structural, and electrical properties of transparent conductive oxide thin films prepared by nebulized spray pyrolysis for photovoltaic applications

• Tin based conducting oxide material is prepared using the starting material Tin (II)Chloride. • The molar ratio of the material varies from 0.1 M to 0.5 M by dissolving in isoproponal and a few drops of Hydrochloric Acid (HCl) for fine dissolution. • The material crystallinity and grain size has been improved while the prepared SnO 2 substrates were annealed. • The morphological study reveals that the grain size and stoichiometric of the prepared material increases when the molar concentration increases with annealing temperature. EDX studies authenticate the presence of required elements (Sn = 85.75 % & O = 11.31 %) and after annealing it shows the elimination of unwanted elements. The optical band gap values are increased from 3.71 eV to 3.75 eV for with and without samples due to quantum confinement effect. Hall Effect studies shows that after annealing the resistivity will be decreased in the order of 10 -3 Ω cm. • FTIR analysis was used to compare the bending and stretching vibrations of the functional groups associated with the O-sn-O bond for both annealed and non-annealed samples. In the present investigation, we are focused on the preparation of Tin based conducting oxide material. The starting material used is Tin (II)Chloride. The molar ratio of the material varies from 0.1 M to 0.5 M by dissolving in isoproponal and a few drops of Hydrochloric Acid (HCl) for fine dissolution. The well-clean Micro slides were coated using the Nebulizer Spray Pyrolysis (NSP) process at a deposition temperature of 350 °C ± 10 °C and annealed at 300 °C for three hours. The structural, optical, electrical, thickness, functional, and morphological studies are validated with and without annealing. The material crystallinity and grain size has been improved while the prepared SnO 2 substrates were annealed. The morphological study reveals that the grain size and stoichiometric of the prepared material increases when the molar concentration increases with annealing temperature. EDX studies authenticate the presence of required elements (Sn = 85.75 %& O = 11.31 %) and after annealing it shows the elimination of unwanted elements. FTIR analysis was used to compare the bending and stretching vibrations of the functional groups associated with the O-sn-O bond for both annealed and non-annealed samples. The optical band gap values are increased from 3.71 eV to 3.75 eV for with and without samples due to quantum confinement effect. Hall Effect studies shows that after annealing the resistivity will be decreased in the order of 10 -3 Ω cm.

Multipurpose nanocomposite resist for free-standing transparent conductive thin films

Nanocomposites formed by silver nanowires (AgNWs) embedded in a polymer matrix are a convenient way to deposit thin films with electrical conductance and high transparency on different substrates. Nanocomposite resists containing AgNWs in a poly(methyl methacrylate) solution can be effectively used to produce conductive coatings in a straightforward manner. Here, we show that by adding a sacrificial layer of polyvinylpyrrolidone on a glass substrate, prior to the nanocomposite resist, it is possible to obtain large-area free-standing films of about 450 nm with electrical conductance and high transparency. The films can be transferred to different surfaces and materials including non-flat substrates. The formation of conductive stacks by piling two layers was also demonstrated. The optical, electrical, and structural properties of these free-standing films were studied obtaining films with transmittance T(%) = 78% at 550 nm, sheet resistance Rs = (670 ± 40) Ω sq−1 and surface roughness Ra = (50 ± 10) nm. We studied the strain resistance behavior of films transferred to polyethylene terephthalate sheets under bending tests finding a sensitivity of (0.51 ± 0.01) Ω deg−1 and a gradual increase in the resistance during cycling. In addition, thin flexible supports can be added by covering the nanocomposite film with polydimethylsiloxane (PDMS) prior to its release, enhancing the mechanical robustness and improving the manipulation of the films.