Spin-casting Method Research Articles

Application of cylindrical covers from glass-metal composite made by spin casting method for strong cases of deep-sea submersibles

In this work the manufacturing techniques of layered constructional material metal-glass-metal are considered by method of centrifugal casting; a similar approach to formation of a glass layer without superficial microcracks has no analogues in the world practice. The scheme of installation for production of cylindrical covers from a glass-metal composite is provided. The research of the main technological modes providing reliable connection of aluminium coverings with the glass which is in a plastic state is conducted. Optimum values of temperature parameters are defined. Methods of electronic microscopy have investigated the diffusive layer which is formed on the glass-aluminium border.

Conductive nonwetting flexible substrate

In this paper an easy method to prepare flexible conductive substrates has been demonstrated. The substrates are mainly PET (PolyEthyleneTerephthalate), on which AgNW (silver nanowire) were deposited by spin casting method. For adhesion purpose a common cosmetic material has been utilized. The material provides versatile features to these coated substrates, including robustness, hydrophobicity with transparent bracing of nanowires (NW) with the flexible substrate. Four probe conductivity measurement shows the resistivity is 12 Ω/cm and is comparable to that of commercially available indium tin oxide (ITO) coated substrates. This method is cheap, easy and can be used for different objectives like flexible thin film photovoltaic, light emitting diodes, photosensors etc.

Molecular organization in MAPLE-deposited conjugated polymer thin films and the implications for carrier transport characteristics

The morphological structure of poly(3-hexylthiophene) (P3HT) thin films deposited by both Matrix Assisted Pulsed Laser Evaporation (MAPLE) and solution spin-casting methods are investigated. The MAPLE samples possessed a higher degree of disorder, with random orientations of polymer crystallites along the side-chain stacking, π–π stacking, and conjugated backbone directions. Moreover, the average molecular orientations and relative degrees of crystallinity of MAPLE-deposited polymer films are insensitive to the chemistries of the substrates onto which they were deposited; this is in stark contrast to the films prepared by the conventional spin-casting technique. Despite the seemingly unfavorable molecular orientations and the highly disordered morphologies, the in-plane charge carrier transport characteristics of the MAPLE samples are comparable to those of spin-cast samples, exhibiting similar transport activation energies (56 vs. 54 meV) to those reported in the literature for high mobility polymers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 39–48

Performance of Superhydrophobic Nano Complex Anti- corrosion Coating Fabricated by Sol-gel Technique

Superhydrophobic complex coatings of mesoporous carbon/silica on stainless steel were prepared by a sol-gel spin cast method. The morphologies, anticorrosion property and hydrophobic- ity of the coatings were characterizd by means of scanning electron microscopy (SEM) and trans- mission electron microscopy (TEM), electrochemical test technique-Tafel curve and electrochemi- cal impedance spectroscopy, as well as water contact angle measurement (CA) respectively. The coatings exhibited varied surface morphologies with bump-like and nipple-like protrusions on the stainless steel substrate. The coatings had a high water contact angle larger than 163°, indicating its strong hydrophobicity. The corrosion current density of the superhydrophobic complex coating coated steel was 8 order of magnitude lower than the bare steel, while its charge transfer resistance (Rct) was 6 order of magnitude higher as well, implying an excellent corrosion protectiveness. Be- sides, an electrochemical equivalent circuit was proposed to interpret the relevant anti-corrosion mechanism for the superhydrophobic coatings.

Dissolvable microneedle arrays for intradermal delivery of biologics: fabrication and application.

Design and evaluate a new micro-machining based approach for fabricating dissolvable microneedle arrays (MNAs) with diverse geometries and from different materials for dry delivery to skin microenvironments. The aims are to describe the new fabrication method, to evaluate geometric and material capability as well as reproducibility of the method, and to demonstrate the effectiveness of fabricated MNAs in delivering bioactive molecules. Precise master molds were created using micromilling. Micromolding was used to create elastomer production molds from master molds. The dissolvable MNAs were then fabricated using the spin-casting method. Fabricated MNAs with different geometries were evaluated for reproducibility. MNAs from different materials were fabricated to show material capability. MNAs with embedded bioactive components were tested for functionality on human and mice skin. MNAs with different geometries and from carboxymethyl cellulose, polyvinyl pyrrolidone and maltodextrin were created reproducibly using our method. MNAs successfully pierce the skin, precisely deliver their bioactive cargo to skin and induce specific immunity in mice. We demonstrated that the new fabrication approach enables creating dissolvable MNAs with diverse geometries and from different materials reproducibly. We also demonstrated the application of MNAs for precise and specific delivery of biomolecules to skin microenvironments in vitro and in vivo.

Fabrication of solution-processed hydrogenated amorphous silicon single-junction solar cells

Hydrogenated amorphous silicon solar cells were fabricated using solution-based processes. All silicon layers of the p-i-n junction were stacked by a spin-cast method using doped and non-doped polydihydrosilane solutions. Further, a hydrogen-radical treatment under vacuum conditions was employed to reduce spin density in the silicon films. Following this treatment, the electric properties of the silicon films were improved, and the power conversion efficiency of the solar cells was also increased from 0.01% to 0.30%–0.51% under the AM-1.5G (100 mW/cm2) illumination conditions.

Simple fabrication of single- and multi-layer polymer nanotubes by spin-casting method within anodized aluminum oxide (AAO) templates

Polymer nanotubes (PNTs) were fabricated by a simple spin casting of the polymer solution into nanochannels of anodic aluminum oxide (AAO) membranes. The thickness of the polymer nanotubes could be reproducibly controlled by changing the concentration of the polymer solutions. Furthermore, multiple spin casting of different polymer solutions could produce multi-layer PNTs (MPNTs), whose formation was confirmed by a selective staining technique in transmission electron microscope (TEM) experiments. Luminescent molecules such as blue-emitting Ir(III) complex and orange-emitting rhodamine B derivative could be uniformly incorporated into each polymer layer simply by mixing them into each polymer solution. These dye-incorporated MPNTs could be easily fabricated by the same spin casting method. Their optical properties were determined by UV-Vis spectroscopy, photoluminescence, and fluorescence microscopy. The morphology of the nanotubes was characterized using a field emission-scanning electron microscope (FE-SEM) and TEM. These results showed that the MPNTs could be reproducibly fabricated throughout the length of the nanochannels of the AAO templates.

Study of photovoltaic performance of host‐guest system comprising photoluminescent polyurethane and rhodamine B dye

AbstractThe photovoltaic property of Rhodamine B dye embedded into Poly(tolyl‐1,1′‐binaphthyl carbamate) (PU1) and poly(hexamethylene‐1,1′‐binaphthyl carbamate) (PU2) matrices have been evaluated using host‐guest approach. The photoactive layer comprising photoluminescent polymer matrix (PU1 or PU2), Rhodamine B and TiO2 nanoparticles were prepared by spin casting method. The power conversion efficiency (PCE) the photovoltaic devices based on PU1 and PU2 matrices were found to be 0.043% and 0.029%, respectively. PCE of the photovoltaic devices were limited due to low lying highest occupied molecular orbital of PU1 and PU2 polymers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.

Enhancement of the Hole Injection Current in Polymer Light-Emitting Devices Fabricated Utilizing a Graphene Layer

The electrical and the optical properties of polymer light-emitting devices (PLEDs) fabricated utilizing a graphene hole injection layer (HIL) were investigated to clarify the hole injection enhancement caused by the insertion of the graphene HIL. The graphene was synthesized by using chemical vapor deposition, and the PLEDs with a graphene HIL were fabricated by using spin-casting method. The average transmittance for the graphene film with a thickness of 10 nm was approximately 90%, and the surface of the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer deposited on a graphene layer was smoother than that of the PEDOT:PSS deposited on an indium-tin-oxide layer. While the hole current of the PLEDs with a graphene HIL larger than that of the PLEDs without a graphene layer because of the high conductivity of the graphene film, the luminance efficiency was lower due to the leakage of holes that had not recombined with electrons.

Graphene Oxide Thin Films for Flexible Nonvolatile Memory Applications

There has been strong demand for novel nonvolatile memory technology for low-cost, large-area, and low-power flexible electronics applications. Resistive memories based on metal oxide thin films have been extensively studied for application as next-generation nonvolatile memory devices. However, although the metal oxide based resistive memories have several advantages, such as good scalability, low-power consumption, and fast switching speed, their application to large-area flexible substrates has been limited due to their material characteristics and necessity of a high-temperature fabrication process. As a promising nonvolatile memory technology for large-area flexible applications, we present a graphene oxide based memory that can be easily fabricated using a room temperature spin-casting method on flexible substrates and has reliable memory performance in terms of retention and endurance. The microscopic origin of the bipolar resistive switching behavior was elucidated and is attributed to rupture and formation of conducting filaments at the top amorphous interface layer formed between the graphene oxide film and the top Al metal electrode, via high-resolution transmission electron microscopy and in situ X-ray photoemission spectroscopy. This work provides an important step for developing understanding of the fundamental physics of bipolar resistive switching in graphene oxide films, for the application to future flexible electronics.

Efficient fabrication of wafer scale thin film of individualized single-walled carbon nanotubes by dual-nozzle spin casting

In this paper, a dual-nozzle spin casting method was proposed to form a thin film of individualized single-walled carbon nanotubes (SWNTs) at the wafer scale. Each nozzle simultaneously ejected the SWNT solution and methanol, respectively. During the ejection process, two solutions were mixed at the contacting end of the nozzles and then dropped onto the substrate. Functionalization of the wafer substrate with the amine group improved the uniformity of the SWNT thin film as well as the adhesion between the individualized SWNTs and the substrate. The best condition of the spin casting involved the substrate functionalization using 3-aminopropyltriethosilane aqueous solution with a concentration of approximately 10 mM and a deposition velocity of approximately 5000 rpm. The root-mean-square roughness of the fabricated SWNT layer over the wafer substrate was found to be 1.4-1.8 nm, which indicated that the resultant thin film was one or two layers of SWNTs. The wafer scale SWNT thin film formed by dual-nozzle spin casting can be further used for the mass production and high integration of the SWNT nanoelectronic devices.

Characterization of polyethersulfone/polyimide blend membranes prepared by a dry/wet phase inversion: Precipitation kinetics, morphology and gas separation

Flat sheet gas separation membranes of polyethersulfone (PES), polyimide (Matrimid, MI) and their blends were fabricated by a spin casting method followed by a dry/wet induced phase inversion process. The mixing compatibility and thermal stability of the blend membrane were studied by Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA) respectively. The forming behavior was investigated by the ternary phase diagram and an optical microscope with PES, MI and PES/MI blend (5:5). In this ternary system, the average of diffusion coefficient, D e , of PES, MI and EM5050 were respectively 8.35 × 10 −5, 10.22 × 10 −5 and 3.09 × 10 −5 cm 2/s. The morphology of membranes was studied by a scanning electron microscope (SEM). All prepared membranes had an ultrathin dense skin layer (<1 μm) on the top of the membrane. The blend membrane with MI composition from 40 to 80 wt.% showed sponge-like sub-layer whereas pristine membrane as well as the rest of the composition showed the finger-like sub-layer (macrovoids). Gas permeance of N 2, increased with increase in feed pressure irrespective of blend composition. The permselectivity of PES/MI (30/70 wt.%) decreased from 5.4 to 4.9 with increase in the feed pressure.

Multilayer structured polymer light emitting diodes with cross-linked polymer matrices

Currently, there is great interest in manufacturing multilayer polymer light emitting diode (PLED) structures via low-cost solution-based spin-casting or printing methods. The difficulty with this approach is that solvent from freshly deposited films often dissolves the underlying layers. This letter demonstrates that fully operational multilayer PLED structures can be fabricated via a solution process by embedding the hole transport material in cross-linked inert polymer matrices that protect the functional material while subsequent layers are deposited using the same solvent. The resulting devices exhibited greatly improved quantum efficiency compared with devices that did not employ cross-linked polymer matrices.

Facet Specific Gold Tip Growth on Semiconductor Nanorods

High quality CdS-Au and CdSe-Au hybrid nanocrystals have been developed via facile approaches. Gold tip growth onto II-VI nanorods has been shown to occur instantaneously both via a solution and spin cast method. Gold tip size and multiplicity can be varied by changing the starting gold chloride concentration or the reaction duration. Gold tip growth typically occurs at one end of the nanorod, however we recently observed that a variation in the reaction temperature leads to the growth of a tip on both ends of the nanorod. TEM analysis showed that the gold tip growth does not always occur centrosymmetrically on the rod tip, with growth occurring on either the (001) or the (101) facet depending on the respective sizes. Spin coating gold chloride solution onto a pre-deposited perpendicular oriented array of nanorods leads to individual gold growth at the tips of each nanorod.

Dynamic process of cold crystallization of poly(butylene terephthalate) solids revealed by fluorescence spectroscopy

The crystallinity of poly(butylene terephthalate) (PBT) films was investigated by comparing measurements of fluorescence and density. It was found that the ratio of the fluorescence intensity at 320nm to that at 365nm can be an effective indicator of crystallinity. The dynamic process of cold crystallization was directly observed for PBT films prepared using a spin-casting method on quartz disks by means of fluorescence measurements at several temperatures between 360 and 400K. The cold crystallization of such films was found to proceed one-dimensionally under the mechanism of heterogeneous nucleation, since the Avrami exponent, n, was determined to be one. The apparent activation energy of cold crystallization was determined to be 24kJ/mol, indicating that rotation around carbon–carbon bonds in a butylene unit of PBT participates in reorientation and crystallization. The present work should provide a quick and nondestructive method for determining the crystallinity of PBT factory products.

Synthesis and characterization of high-integrity solid-contact polymeric ion sensors

High integrity solid-contact (SC) polymeric ion sensors have been produced by using spin casting and electropolymerization techniques in the preparation of the SC employing the conductive polymer, poly(3-octylthiophene) [POT]. The physical and chemical integrity of the POT SCs have been evaluated using scanning electron microscopy (SEM), atomic force microscopy (AFM), secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS). Furthermore, the electrochemical stability of SC polymeric ion sensors has been investigated using electrochemical impedance spectroscopy (EIS). The results of this study demonstrate that electropolymerization and spin casting methods also comprising annealing of the synthesized SC film are capable of producing SCs that are relatively free of imperfections such as pores and pinholes. This leads to electrochemically stable and robust polymeric ion sensors where the SC/sensor interface is resistant to the formation of a detrimental water layer that normally gives rise to spurious ion fluxes and a degradation in the sensitivity and selectivity of the SC polymeric ion sensor.

Electrical properties of dysprosium phthalocyanine films

Forty-four nanometers thick films of alkyl-substituted dysprosium phthalocyanine molecules were prepared on carefully cleaned indium tin oxide (ITO) substrates by the spin casting method. UV–vis absorption spectra and dc conduction characteristics were obtained in order to investigate the structure–conduction property relationship. The conduction is Ohmic at low applied voltages but the space charge limited mechanism is prevalent at relatively high voltages. The conductivities of both as-deposited and heat treated films are found to show directionally anisotropic behaviour. The columnar conductivity was found to be significantly large in the liquid crystalline state.

Preparations of self-supporting nanofilms of metal oxides by casting processes.

We recently developed a solution-based method for the preparation of self-supporting (free-standing) titania films with thicknesses less than a micrometre. In this study, we demonstrated its wide applicability to other metal oxides. Film fabrication by spin casting was employed for preparation of self-supporting nanofilms (<100 nm thickness) from various combinations of metal oxides, polymer underlayers, and polymer middle layers. All the metal alkoxides we examined gave self-supporting ultrathin films of AlO, NbO, ZrO, SiO and LaO. It was found that the photoresist polymer underlayer employed for ready film detachment could be replaced by other commercial polymers. The polymer underlayer could be omitted when a cast acrylic sheet was used as the solid substrate. The importance of the PVA middle layer was confirmed by successful formation of uniform large metal oxide films compared to the case of other polymers. This is attributed to a high population of the surface hydroxyl group that facilitates efficient development of lateral metal oxide network within the film. Admixing of organic carboxylic acids in the casting solution provided similarly uniform metal oxide nanofilms. These results revealed that the spin casting method is applicable to a wide variety of metal oxides and polymer layers.We also developed the flow casting method for film fabrication and its usefulness was discussed. These newer approaches were compared with the surface sol-gel process which we previously described. Among the three casting methods, the spin casting method was most effective for obtaining uniform large nanofilms of metal oxides by simple operation, although it was limited to flat surfaces.

Efficient white-light-emitting diodes based on polymer codoped with two phosphorescent dyes

Efficient white-light-emitting diodes (WPLEDs) based on a polymer codoped with two phosphorescent dyes were fabricated by the spin-casting method. Polyhedral oligomeric silsesquioxane-terminated poly(9,9-dioctylfluorene) (PFO-poss) was used as the host and blue light emitter. Phosphorescent emitters, fac-tris[2-(4′-ter-butyl)phenylpyridine] iridium (III) [Ir(Bu-ppy)3] and bis-(1-phenylisoquinolyl)iridium(III)(1-trifluoro) acetylacetonate [(Piq)2Ir(acaF)] with green and red emission, respectively, were used as the guests. The electroluminescence spectrum can be tuned by changing concentration of the guests. The structure of the WPLEDs is indium tin oxide (ITO)/poly(ethlenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS)/ PVK/PFO-poss codoped with Ir(Bu-ppy)3 and (Piq)2Ir(acaF)∕Ba∕Al. The PVK layer [poly(N-vinylcarbazole)] acts as the function of blocking electron penetrating from PFO-poss to PEDOT. When the doping concentrations are 0.14 wt % for both Ir(Bu-ppy)3 and (Piq)2Ir(acaF), the efficient white-light emission with CIE coordinates of around (0.33, 0.33) is achieved. The current efficiency reaches 5.5lm∕W (9cd∕A), and the maximum luminance of 10200cd∕m2 was gained at 11 V. The mechanisms of the WPLEDs with high efficiency are discussed.

Narrow bandwidth red electroluminescence from solution-processed lanthanide-doped polymer thin films

Narrow bandwidth red electroluminescence from OLED devices fabricated using a simple solution-based approach is demonstrated. A spin-casting method is employed to fabricate organic light emitting diode (OLED) devices comprising a poly( N-vinylcarbazole) (PVK) host matrix doped with a europium β-diketonate complex, Eu(dbm) 3(Phen) (dibenzoylmethanate, dbm; 1,10-phenanthroline, Phen) on glass/indium tin oxide (ITO)/3,4-polyethylene-dioxythiophene-polystyrene sulfonate (PEDOT) substrates. Saturated red europium ion emission, based on the 5D 0 → 7F 2 transition, is centered at a wavelength of 612 nm with a full width at half maximum of 3.5 nm. A maximum external quantum efficiency of 6.3 × 10 − 2 cd/A (3.1 × 10 − 2 %) and a maximum luminance of 130 cd/m 2 at 400 mA/cm 2 and 25 V is measured for ITO/PEDOT/PVK:Eu(dbm) 3(Phen)/Ca/Al devices. This measured output luminance is comparable to that of devices fabricated using more sophisticated small molecule evaporation techniques.