Spray-coating Technique Research Articles

Anti-corrosion, anti-bacterial and durable atmospheric weatherability of polydimethylsiloxane coating with intrinsic hydrophobicity

Understanding the corrosion resistance, microorganism suppression and real-world weatherability and application potentiality of intrinsically hydrophobic polydimethylsiloxane (PDMS) coating is of great significance for developing multi-functional composite protective materials. In this paper, a pure PDMS coating was prepared through spray-coating technique on Q235 carbon steel. The surface morphologies, wettability, chemical compositions, corrosion resistance, bacteria adhesion and real-world atmospheric durability behaviors were investigated. The electrochemical assessment results show that the PDMS-coated Q235 carbon steel exhibits greatly enhanced charge transfer resistance (R ct), positive movement of corrosion potential (E corr), and extremely low corrosion current density (I corr). Besides, the PDMS coating presents high anti-bacterial efficiency against Escherichia coli and Pseudomonas sp. adhesion. The real-world atmospheric weatherability, salt spray and abrasion resistance reveal that the PDMS coating can be considered as a superior and durable barrier against marine corrosion and biofouling invasion.

Facile Fabrication of Highly Sensitive Thermoplastic Polyurethane Sensors with Surface- and Interface-Impregnated 3D Conductive Networks.

This research aims to develop a practical, scalable, and highly conductive flexible 3D printed piezoresistive sensor with low filler content. Here, we introduced a fused deposition modeling 3D printing combined in situ spray-coating technique to develop a conductive sensor in a single shot. The graphene suspension is sprayed over each layer during the 3D printing of the sensor, which helps develop a conductive network on the surface and at the interface of the printed system. Graphene deposited on the overall surface is often affected by nanoparticle delamination and loses its function over time. To avoid this, the prepared samples are subjected to foaming. The foaming process created a low-mass-density sensor by forming a microcellular structure, and the surface-deposited graphene is embedded well on the TPU surface. The method followed in this work reveals a stable and connected conduction path with excellent electrical resistance and resistance against harsh conditions (exposure to organic solvents). Besides, the compression sensor withstood its sensitivity over a severe compressive strain of 80% and showed a GF of 1.82 and a sensitivity of 2.316 kPa-1. The conductive network path varied based on the infill pattern, affecting its electrical sensitivity. The wiggle pattern shows good resistance; under stretching, the pattern generated a higher current and showed a delayed conductive path disconnection than other patterns. Thus, the embedded graphene/TPU conductive sensors show good stability and promising sensitivity. Furthermore, the developed sensor is used to monitor human motion and actions.

FEA Analysis and Experimental Investigation of the Ceramic Coating on Aluminum Piston Material By Plasma Spray Coating Technique

Abstract: Functionally graded materials are of widespread interest because of their superior properties such as corrosion, erosion and oxidation resistance, high hardness, chemical and thermal stability at cryogenic and high temperatures. These properties make them useful for many applications, including Thermal Barrier Coating (TBC) on metallic substrates used at high temperatures in the fields of aircraft and aerospace, especially for thermal protection of components in gas turbines and diesel engines. The application of TBC reduces the heat loss to the engine cooling-jacket through the surface exposed to the heat transfer such as the cylinder head, liner, piston crown and piston rings. The insulation of the combustion chamber with ceramic coating affects the combustion process and, hence, the performance and exhaust emissions characteristics of the engines improve. In this project, the main emphasis is placed on the study of thermal behavior of functionally graded coatings obtained by means of using a commercial code, ANSYS on aluminum and steel piston surfaces and the results are verified with numerical and experimental works. Keywords: Thermal Barrier Coating, Piston, Insulation, Corrosion, ANSYS, engine cooling-jacket.

Enhanced Joule heating performance of flexible transparent conductive double-walled carbon nanotube films on sparked Ag nanoparticles

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.

Superhydrophobic/superoleophilic starch-based cryogels coated by silylated porous starch/Fe3O4 hybrid micro/nanoparticles for removing discrete oil patches from water

Development of novel superhydrophobic adsorbents to remove oil spills that threaten aquatic ecosystems is necessary. To realize smart superhydrophobic starch-based adsorbents and reduce the use of metal-oxide particles in magnetic superhydrophobic coating, silylated porous starch/Fe3O4 hybrid micro/nanoparticles (SPF) were developed, and then innovatively introduced onto the surface of starch cryogel (SPF@SC) by spray-coating technique. The surface chemical composition and hierarchical micro/nanostructures, which contribute to the high water contact angle (>152.0°) and low sliding angle (<9.0°) of the as-prepared material, were characterized in detail. SPF@SC possessed excellent water repellent, self-cleaning, and anti-fouling properties, as well as good mechanical and chemical durability. SPF@SC can be remotely propelled by a magnet on the surface of water to flexibly clean discrete oil patches. Moreover, an internal/external collaborative oil absorption behavior was also found unexpectedly in the absorbent. This study provides a strategy for the design of novel adsorbents that could be applied to tackle discrete oil contaminates over the ocean.

Surface Treatment of Flexible Barrier Film for Improved Stability of Organic Photovoltaic Mini Modules

The lifetime and stability of organic photovoltaics (OPVs) are the key factors that influence the technology used to scale up and commercialize OPVs. High-performing and reliable devices are used to fabricate the devices of choice. Materials and methods that can be used to prevent the degradation of organic materials, enabling better OPV applications, are being increasingly researched in recent years. Herein, we present the surface modification process of a commercial, flexible barrier film based on polyethylene terephthalate (PET). A sol-gel deposition method was used to modify the surface. Two scalable coating techniques, spray- and bar-coating, were investigated as the processing methods. Treated films were optically, morphologically, and topologically characterized. The modification of the barrier film surface increased the surface hydrophobicity of the bar-coated and spray-coated treated films. This was validated by the contact angle measurements. OPV roll-to-roll (R2R) mini-modules with 4.2% power conversion efficiency were fabricated and encapsulated with the treated films. The lifetime and stability were assessed by conducting accelerated aging tests based on the ISOS-D-3 protocol. The spray-coating technique provided a more stable layer than the bar-coating technique, and the lifetime of the OPV modules encapsulated in spray-coated treated barrier films was increased. Surface modification has been demonstrated to be a promising approach for not only improving the barrier film properties (resulting in the improved lifetimes of the modules) but also reducing the extents of reflectance losses in the OPV modules post encapsulation.

Mesoporous silica-based abrasion resistant antireflective (AR)-cum-hydrophobic coatings on textured solar cover glasses by a spray coating technique

The present work describes the fabrication of functionalized mesoporous silica based antireflective-cum-hydrophobic coatings on textured solar cover glasses via a spray-coating technique exhibiting enhanced photo-current density.

Large‐Area Fabrication of High Performing, Flexible, Transparent Conducting Electrodes Using Screen Printing and Spray Coating Techniques

AbstractFabrication of large‐area transparent conducting electrodes (TCEs) of high performance through cost‐effective high throughput methods has been an area of intensive research. In this context, the fabrication of flexible, 25 cm2 wide TCEs with high figure of merit (FoM) (≈494 Ω−1 ) is achieved by two roll‐to‐roll compatible processes, namely screen printing and spray coating, by suitably modifying crackle lithography in a cost‐effective manner. The fabricated TCEs exhibit low sheet resistance (&lt;10 Ω □−1) and high transmittance (≈86–90%) in the visible region. The TCEs are shown to be highly bendable, the change in the sheet resistance is only ≈2% up on 6000 bending cycles. The application of these TCEs as transparent bendable uniform Joule heaters and surface capacitive touchscreens has also been demonstrated. The TCEs are, thus, just as good as any TCE produced using spin‐coating or similar small area coating techniques.

Molecular-level fabrication of highly selective composite ZIF-8-CNT-PDMS membranes for effective CO2/N2, CO2/H2 and olefin/paraffin separations

The molecular-scale fabrication method of unique CNT-ZIF-8-PDMS composite membranes with enhanced gas separation performance mainly focusing on CO2 capturing (CO2/N2, CO2/H2). Also olefin/paraffin separation is reported. For the first time, a successful synthesis of ZIF-8 gutter-layer on the free-standing chemically modified carbon nanotube (CNT) platforms was conducted via the ZnO linkages enabling the proper inter-grown and strong anchoring ZIF-8 crystals onto the CNT. The formation of aligned ZIF-8 arrays onto the CNT surface acted as an effective buffering layer that boosted the molecular gas transport through the membrane. In contrast, the conventional gutter layers which usually reduced the gas permeability. To diminish the interstitial pores at the surface/bulk of the CNT/ZIF-8 formations, thin polydimethylsiloxane (PDMS) layer was deposited via the spray-coating technique on the CNT/ZIF-8. The resulting non-defect morphology was confirmed by the SEM and the 3D optical profilometer observations. Furthermore, the PDMS deposition improved mechanical stability (stress vs. strain) of the composite with a twelvefold increased elongation and thermal stability led to a 46% mass reduction. Moreover, composite membranes exhibited outstanding gas separation performance with high CO2 and C3H6 permeabilities of 8705 and 4965 Barrer, respectively and selectivities overcoming the appropriate 2008 Robeson upper bounds for various gas pairs CO2/N2 (ideal selectivity α = 45.6) and CO2/H2 (α = 23.9) gas pairs. Similarly, achieved results of the other tested gas pairs, e.g. CO2/SF6 (α = 17.2), C3H6/N2 (α = 26.0) and C3H6/C3H8 (α = 4.9) were further remarkable in comparison with the literature. Hence, the CNT-ZIF-8-PDMS composite membrane concept has the excellent potential for the fabrication of efficient membranes suitable for targeted gas separation with high commercial and environmental relevance, such as the greenhouse gasses, hydrocarbons recovery for energy harvesting, CO2 capturing and olefin/paraffin separation.

Analysis of Fe-doped ZnO thin films for degradation of rhodamine b, methylene blue, and Escherichia coli under visible light

ZnO is a popular photocatalyst that is often used for the degradation of dyes and bacteria. However, the catalytic performance of ZnO is only optimal under UV light exposure. This study aims to determine the degradation performance of rhodamine b, methylene blue, and Escherichia coli using 0, 5, 10, 15, and 20% Fe-doped ZnO (ZnO:Fe). Deposition of thin film was carried out using the sol-gel method with a spray-coating technique, while the degradation was carried out under halogen light exposure for 3 h. The optical characterization results show that 20% Fe-doped ZnO has the highest transmittance and the lowest energy band gap of 3.21 eV based on Tauc’s plot method. All thin films are hydrophilic with the largest contact angle of 68.54° by 20% Fe-doped ZnO and the lowest contact angle of 52.96° by 5% Fe-doped ZnO. The surface morphology of the thin film resembles a creeping root that is cracked and agglomerated. XRD test results show that the thin film is dominated by ZnO peaks with a wurtzite structure with a hexagonal plane phase and a crystal size of 115.5 A°. The 20% Fe-doped ZnO thin film had the most efficient degradation performance of 70.79% for rhodamine b, 65.31% for blue, and 67% for E. coli bacteria. Therefore, Fe-doped ZnO is a brilliant photocatalyst material that can degrade various pollutants even under visible light.

Large-Area Fabrication of Structurally Colored and Humidity Sensitive Composite Nanofilm via Ultrasonic Spray-Coating.

Intelligent structural colors have received extensive attention in recent years due to their diverse applications. However, the large-area, uniform, and cost-effective fabrication of ultra-thin structural color films is still challenging. Here, for the first time, we design and employ an ultrasonic spray-coating technique with non-toxic, green nano-silica and polyvinylpyrrolidone as raw materials, to prepare structural color films on silicon wafers. Due to the addition of polyvinylpyrrolidone, the coffee-ring effect during droplet drying is suppressed and uniform composite films are formed. We further perform a detailed study of the influence of various processing parameters including silica/polyvinylpyrrolidone concentration, substrate temperature, nozzle-to-substrate distance, and number of spray-passes on film roughness and thickness. By increasing the number of spray-passes from 10 to 30, the film thickness from 120 to 340 nm is modulated, resulting in different colors, and large-area and uniform colors on commercial round silicon wafers with 15 cm diameter are achieved. The silica/polyvinylpyrrolidone composite films show strong hydrophilicity and are sensitive to humidity changes, leading to quickly tunable and reversible structural colors. Quartz crystal microbalance with dissipation demonstrates water vapor adsorption and condensation on the nanofilm when increasing environmental humidity. Thereby, ultrasonic spray-coating as a novel film fabrication technique provides a feasible scheme for large-area preparation of intelligent structural colors.

Oxygen-Enriched α-MoO3– nanobelts suppress lithium dendrite formation in stable lithium-metal batteries

In this study, MoO 3 nanobelts (MNBs) are passivated on lithium (Li) metal anodes to suppress Li dendrite formation and, thereby improve the stability in Li-metal batteries. MoO 3 powder is ground into MNBs using a commercially viable mechanical grinding technique. The MNBs are then coated on Li metal using a simple spray-coating technique. The MNBs on top of the pristine Li mitigates the formation of Li dendrites by generating a uniform Li + ion flux and providing shorter diffusion pathways. This facile passivation strategy prevents the growth of undesirable dendrites on pristine Li surfaces. A live transparent Li–Li symmetrical cell having MoO 3 -coated Li anode (MNB-Li) does not form any Li dendrites and undergoes minimal surface degradation relative to that of the corresponding pristine Li cell. The Li–Li symmetrical cells featuring the MoO 3 -coated surface operate with a low overpotential of approximately 18 mV for an extremely long period of time (ca. 2500 h) at a current density of 1 mA cm −2 . A Li–sulfur battery featuring the MNB-Li at 0.5 C significantly improves stability, with an initial capacity of 1127 mAh g −1 , a capacity of 820 mAh g −1 for up to 200 cycles, and an excellent coulombic efficiency of 98.12 %. • Passivation layer of MoO 3 nanobelts (MNBs) suppress the Li dendrites on Li anode. • Shorter diffusion pathways by MNBs allow the easy migration of Li + ions. • The O 2 vacancies in MNBs boost carrier concentration and act like shallow donors. • This facile strategy demonstrates a stable anode and better cycling performance.

Superhydrophobic and Self-Sterilizing Surgical Masks Spray-Coated with Carbon Nanotubes

Coronavirus has affected the entire global community owing to its transmission through respiratory droplets. This has led to the mandatory usage of surgical masks for protection against this lethal virus in many countries. However, the currently available disposable surgical masks have limitations in terms of their hydrophobicity and reusability. Here, we report a single-step spray-coating technique for the formation of a superhydrophobic layer of single-walled carbon nanotubes (SWCNTs) on a melt-blown polypropylene (PP) surgical mask. The sprayed SWCNTs form a nanospike-like architecture on the PP surface, increasing the static contact angle for water from 113.6° ± 3.0° to 156.2° ± 1.8° and showing superhydrophobicity for various body fluids such as urine, tears, blood, sweat, and saliva. The CNT-coated surgical masks also display an outstanding photothermal response with an increase in their surface temperature to more than 90 °C within 30 s of 1 sun solar illumination, confirming its self-sterilization ability. Owing to the cumulative effect of the superhydrophobicity and photothermal performance of the SWCNTs, the CNT-coated masks show 99.99% higher bactericidal performance toward Escherichia coli than pristine masks. Further, the virucidal ability of the SWCNT-coated mask, tested by using virus-like particles, was found to be almost 99% under solar illumination. As the spray-coating method is easily scalable, the nanotube-coated mask provides cost-effective personal protection against respiratory diseases. © 2021 American Chemical Society.

Fabrication of thermally and mechanically stable superhydrophobic coatings for cellulose-based substrates with natural and edible ingredients for food applications

This study successfully fabricated double-layer superhydrophobic coatings possessing good thermal and mechanical stability for cellulose-based substrates using natural and edible ingredients by a simple and low-cost casting and spray-coating technique. The first layer of the coatings was prepared by spray-coating the surfactant-free beeswax or camellia wax emulsion for providing high surface roughness and low surface energy to the coatings. Wax concentration (5, 10, and 20 mg/ml) and spray coating time (5, 10, 20, 30 s) were investigated on coating density and superhydrophobicity. The underneath second layer composed of zein particles (ZP)/cellulose nanofiber (CNF) or precipitated calcium carbonate (PCC)/CNF with different thickness (0.1, 0.3, 0.5, and 0.7 mm), was prepared by casting. The prepared coatings had micro/submicron-scale structure surface morphology. A variety of liquid foods could freely roll on the coated filter paper surfaces in spherical without leaving a trace. The introduction of PCC/CNF as the second layer significantly (P < 0.05) increased the thermal and cold stability of the superhydrophobic coatings. The apparent contact angle of PCC/CNF coatings remained to be above 150° after 30 min heating under 80 °C or 24 h cold storage under −20 °C. The mechanical stability of the two-layer coatings with PCC/CNF was also improved significantly (P < 0.05) compared with wax only single-layer coating during abrasion test. Superhydrophobic coatings prepared with beeswax showed more homogenous morphology compared to candelilla wax due to lower melting point of beeswax. The developed thermo- and abrasion-resistant edible superhydrophobic coatings can potentially be employed for a broad range of applications in food packaging.

Superhydrophobic surface with excellent mechanical robustness, water impact resistance and hydrostatic pressure resistance by two-step spray-coating technique

Superhydrophobic surfaces (SHSs) exhibit outstanding liquid-repellent properties, attracting numerous attentions from both academia and industry. However, their weak mechanical robustness and poor water impact resistance still limit their practical applications. Herein, SHSs were fabricated by a simple and scalable two-step spray-coating technique, i.e., spray-coating micro-particles as bottom layer, followed by spray-coating nanoparticles onto the micro-particles as top layer; both micro- and nano-features were firmly affixed by low-surface-energy polymer binder. By carefully tuning the micro-particle ratio in bottom layer and mixed solvent ratio in top layer, we obtained the optimized micro/nano- hierarchical structures, which offered the SHSs super-repellence to various liquids (e.g., water, blood and honey) and excellent mechanical robustness to cloth wipe, eraser rub, multi-cycled sandpaper abrasion and tape peel-off. The SHSs withstood high-speed droplet impact and water jet impact with water impact speed of up to ~9.5 m/s (corresponding to ~3760 of Weber value). In addition, they maintained the superhydrophobicity under a hydrostatic pressure of 0.1 MPa for more than one month, or 3 MPa for more than 12 h, which is the highest record ever reported.

Superhydrophobic self-similar nonwoven-titanate nanostructured materials

HypothesisSelf-similarity is a scale-invariant irregularity that can assist in designing a robust superhydrophobic material. A combinatorial design strategy involving self-similarity and dual-length scale can be employed to create a new library of a doubly re-entrant, disordered, and porous network of superhydrophobic materials. Asymmetric wettability can be engineered in nonwoven materials by rendering them with superhydrophobic characteristics on one side. ExperimentsA facile, scalable, and inexpensive spray-coating technique was used to decorate the weakly hydrophobicstearate-treatedtitanate nanowires (TiONWs)over the self-similar nonwoven material. Laser scanning confocal microscopy was employed to image the impalement dynamics in three dimensions. With the aid of X-ray microcomputed tomography analysis, the three-dimensional (3D) nonwoven structural parameters were obtained and analyzed. The underwater superhydrophobic behavior of the prepared samples was investigated. FindingsA classic 'lotus effect' has been successfully endowed in self-similar nonwoven-titanate nanostructured materials (SS-Ti-NMs) from a nonwoven material that housed the air pockets in bulk and water repellent TiONWs on the surface. The finer fiber-based SS-Ti-NMs exhibited lower roll-off angles and a thinner layer of water on its surface. An asymmetric wettability and the unusual display of underwater superhydrophobic behavior of SS-Ti-NMs have been uncovered.

Oxygen Gas and UV Barrier Properties of Nano-ZnO-Coated PET and PHBHHx Materials Fabricated by Ultrasonic Spray-Coating Technique.

Ultrasonic spray-coating (USSC)—a wet chemical deposition method to deposit ultrathin (down to 20 nm) coatings—is being applied as a promising alternative deposition method for functional coatings due to an economical, simple, and precise coating process with easy control over its operating parameters. In this research, zinc oxide nanoparticles (ZnO NPs) were ultrasonically spray-coated on commercial-grade polyethylene terephthalate (PET) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) films. The most suitable parameters for the ink composition, the ultrasonic spray-coating process, and the number of coating passes (up to 50×) were selected on the basis of a series of experiments. The oxygen gas barrier properties in terms of the oxygen transmission rate (OTR) of neat PET, and 3×, 5×, 10×, and 50× ZnO NP-coated PET and PHBHHx substrates were investigated. The OTR values for neat PET, and 3×, 5×, and 10× ZnO NP-coated PET substrates were found to be the same; however, a 5% reduction in OTR for 50× ZnO NP-coated PET substrate was observed compared to the neat PET substrate. No reduction in OTR was found for any above number of coating passes on PHBHHx substrates against the neat PHBHHx substrate. However, the ultraviolet (UV) tests of 3×, 5×, and 10× ZnO NP-coated PET and PHBHH× substrates revealed a significant decrease in percentage transmission for 10× coated PET and PHBHHx substrates as compared to their 3× and 5× ZnO NP-coated substrates, respectively. It was revealed from the study that the 50× ZnO NP coating of the PET substrate created a slight difference in OTR as compared to the reference substrate. However, the ultrasonic spray-coating method created a significant UV barrier effect for 3×, 5×, and 10× ZnO NP-coated PET and PHBHHx substrates, which demonstrates that the optimized coating method cannot be used to create a high oxygen barrier but can certainly be applied for UV barrier applications in food packaging. It is concluded that ultrasonic spray deposition of ZnO NPs on PET and PHBHHx materials has shown promising results for UV barrier properties, demonstrating the advantages of using this method compared to other coating methods with regard to cost-effectiveness, precise coating, and better process control.

Ligand-Controlled Electrochromic Diversification with Multilayer Coated Metallosupramolecular Polymer Assemblies.

Designing surface-confined molecular systems capable of expressing changes in functional properties as a result of slight variations in chemical structure under the influence of an external stimulus is of contemporary interest. In this context, we have designed three tetraterpyridine ligands with variations in their core architecture (phenyl vs tetraphenylethynyl vs bithiophene) to create spray-coated electrochromic assemblies of iron(II)-based metallosupramolecular polymer network films on transparent conducting oxide substrates. These assemblies exhibited molecular permeability and spectroelectrochemical properties that are in turn dictated by the ligand structure. Electrochromic films with high coloration efficiencies (up to 1050 cm2/C) and superior optical contrast (up to 76%) with a concomitant color-to-color redox transition were readily achieved. These functional switching elements were integrated into sandwich-type electrochromic cells (CE up to 641 cm2/C) that exhibited high contrast ratios of up to 56%, with attractive ON-OFF ratios, fast switching kinetics, and high operational stability. Every measurable spectroelectrochemical property of the films and devices is an associated function of the ligand structure that coordinates the same metal ion to different extents. While exhibiting a ligand-structure induced differential metal coordination leading to porosity and spectroelectrochemical diversification, these assemblies allow the creation of electrochromic patterns and images by a simple spray-coating technique.

Carbon nanotubes and wolfram oxide nanoparticles spray coating on polymer photoactive layer

The spray-coating technique to form top transparent conductive and buffer uniform layers of carbon nanotubes (CNTs) and tungsten oxide nanoparticles (nWO3) from the solvents mixture on MEH-PPV layer, providing minimal underlying layer dissolution and acceptable interface quality, was proposed and can be used for solar cells (SC). The effect of neighboring layers mixing on the electrical characteristics of organic SC and methods for minimizing this mixing by optimizing solution composition, which was selected based on the MEH-PPV solubility and the stability of CNT dispersion, were studied. The dipping degree of CNTs and nWO3 in MEH-PPV and the interface quality was studied by measuring the CNT layer surface resistance and the nWO3 diameter on the surface, as well as analyzing the CVC hysteresis, photoresponse, and current drop time with forward bias after light off.

Enhanced contact properties of spray-coated AgNWs source and drain electrodes in oxide thin-film transistors

Facile patterning of electrodes is required for various electronic applications, particularly in solution-processed oxide thin-film transistors (TFTs). In this study, source and drain electrodes were prepared from silver nanowires (AgNWs) using spray-coating and hot press techniques. Although spray coating allowed production of AgNW patterns, which could function as electrodes in oxide TFT, the as-sprayed films did not provide a sufficient physical contact with oxide semiconductors and formed interspaces that impeded electron injection. At the same time, hot press technique produced denser AgNW networks that had a tight contact with the oxide semiconductors. As a result, hot-pressed films were considered as satisfactory source and drain electrodes for high-performance oxide TFTs, as they provided an easy electron injection. Finally, the prepared oxide TFTs with hot-pressed AgNW electrodes exhibited average field-effect mobility of 4.75 ± 1.5 cm2/V, significantly higher than that of the TFTs with as-sprayed AgNW electrodes (0.08 ± 0.05 cm2/V).