A comparative study of spin coated and floating film transfer method coated poly (3-hexylthiophene)/poly (3-hexylthiophene)-nanofibers based field effect transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tiwari, Shashi; Balasubramanian, S. K.; Takashima, Wataru

2014-09-07

A comparative study on electrical performance, optical properties, and surface morphology of poly(3-hexylthiophene) (P3HT) and P3HT-nanofibers based “normally on” type p-channel field effect transistors (FETs), fabricated by two different coating techniques has been reported here. Nanofibers are prepared in the laboratory with the approach of self-assembly of P3HT molecules into nanofibers in an appropriate solvent. P3HT (0.3 wt. %) and P3HT-nanofibers (∼0.25 wt. %) are used as semiconductor transport materials for deposition over FETs channel through spin coating as well as through our recently developed floating film transfer method (FTM). FETs fabricated using FTM show superior performance compared to spin coated devices;more » however, the mobility of FTM films based FETs is comparable to the mobility of spin coated one. The devices based on P3HT-nanofibers (using both the techniques) show much better performance in comparison to P3HT FETs. The best performance among all the fabricated organic field effect transistors are observed for FTM coated P3HT-nanofibers FETs. This improved performance of nanofiber-FETs is due to ordering of fibers and also due to the fact that fibers offer excellent charge transport facility because of point to point transmission. The optical properties and structural morphologies (P3HT and P3HT-nanofibers) are studied using UV-visible absorption spectrophotometer and atomic force microscopy , respectively. Coating techniques and effect of fiber formation for organic conductors give information for fabrication of organic devices with improved performance.« less

Corrosion resistance and adhesion strength of a spin-assisted layer-by-layer assembled coating on AZ31 magnesium alloy

NASA Astrophysics Data System (ADS)

Zhao, Yan-Bin; Liu, Han-Peng; Li, Chang-Yang; Chen, Yong; Li, Shuo-Qi; Zeng, Rong-Chang; Wang, Zhen-Lin

2018-03-01

A polyvinylpyrrolidone (PVP)/polyacrylic acid (PAA) layer-by-layer (LbL) assembled composite coating with a multilayer structure for the corrosion protection of AZ31 magnesium alloy was prepared by a novel spin-casting method. The microstructure and composition of this coating were investigated by means of SEM, XRD and FT-IR measurements. Moreover, electrochemical, immersion and scratch tests in vitro were performed to measure the corrosion performance and the adhesion strength. These results indicated that the (PVP/PAA)10 composite coating with defect-free, dense and uniform morphologies could be successfully deposited on the surface of magnesium alloy. The coating had excellent corrosion resistance and adhesion strength.

Passivation properties of alumina for multicrystalline silicon nanostructure prepared by spin-coating method

NASA Astrophysics Data System (ADS)

Jiang, Ye; Shen, Honglie; Yang, Wangyang; Zheng, Chaofan; Tang, Quntao; Yao, Hanyu; Raza, Adil; Li, Yufang; Huang, Chunlai

2018-02-01

In this paper, we report passivation properties of inverted pyramidal nanostructure based multi-crystalline silicon (mc-Si) by Al2O3 films with spin-coating method. Precursors AlCl3 and Al(acac)3 for Al2O3 films were chosen for comparison. Al2O3/SiO x stacks were found to be able to passivate the nanostructured surface well. With the number of spin-coating up to five, the Al2O3 films could conformally attach the nanostructure. The weighted average reflectance values (ranging from 400-900 nm) of the passivated silicon surface could be reduced to 10.74% (AlCl3) and 11.12% (Al(acac)3), and the effective carrier lifetime could reach 7.84 and 16.98 μs, respectively. This work presented a potential process to fabricate low cost high efficiency mc-Si solar cells.

Study of blended conductive graft copolymer with graphite oxide thin films deposited using spin coating method for gas sensing and photovoltaic applications

NASA Astrophysics Data System (ADS)

KałuŻyński, P.; Procek, M.; Stolarczyk, Agnieszka; Maciak, E.

2017-08-01

This work presents an investigation on conductive graft comb copolymer like SILPEG CH9 with carbon materials like graphite oxide or reduced graphite oxide. Morphology and optical properties like sample roughness, graphite oxide particles distribution, optical transmittance were measured of obtained thin films deposited on glass substrate using spin coating method. The study showed that obtained thin films are repeatable, convenient to process, and their parameters can be easy changed by the spin rate regulation during the deposition. Given results shows the possibility of using such polymer blend in the implementation of organic photovoltaic cells and different optoelectronics applications.

Carbon decorative coatings by dip-, spin-, and spray-assisted layer-by-layer assembly deposition.

PubMed

Hong, Jinkee; Kang, Sang Wook

2011-09-01

We performed a comparative surface analysis of all-carbon nano-objects (multiwall carbon nanotubes (MWNT) or graphene oxide (GO) sheets) based multilayer coatings prepared using three widely used nanofilm fabrication methods: dip-, spin-, and spray-assisted layer-by-layer (LbL) deposition. The resultant films showed a marked difference in their growth mechanisms and surface morphologies. Various carbon decorative coatings were synthesized with different surface roughness values, despite identical preparation conditions. In particular, smooth to highly rough all-carbon surfaces, as determined by atomic force microscopy (AFM) and scanning electron microscopy (SEM), were readily obtained by manipulating the LbL deposition methods. As was confirmed by the AFM and SEM analyses, this finding indicated the fundamental morphological evolution of one-dimensional nano-objects (MWNT) and two-dimensional nano-objects (GO) by control of the surface roughness through the deposition method. Therefore, an analysis of the three LbL-assembly methods presented herein may offer useful information about the industrial use of carbon decorative coatings and provide an insight into ways to control the structures of multilayer coatings by tuning the morphologies of carbon nano-objects.

Biosensors Based on Urease Adsorbed on Nickel, Platinum, and Gold Conductometric Transducers Modified with Silicalite and Nanozeolites

NASA Astrophysics Data System (ADS)

Kucherenko, Ivan S.; Soldatkin, Oleksandr O.; Kasap, Berna Ozansoy; Kurç, Burcu Akata; Melnyk, Volodymir G.; Semenycheva, Lyudmila M.; Dzyadevych, Sergei V.; Soldatkin, Alexei P.

This work describes urease-based conductometric biosensors that were created using nontypical method of urease immobilization via adsorption on micro- and nanoporous particles: silicalite and nanocrystalline zeolites Beta (BEA) and L. Conductometric transducers with nickel, gold, and platinum interdigitated electrodes were used. Active regions of the nickel transducers were modified with microparticles using two procedures—spin coating and drop coating. Gold and platinum transducers were modified with silicalite using drop coating since it was more effective. Scanning electron microscopy was used to evaluate effectiveness of these procedures. The procedure of spin coating produced more uniform layers of particles (and biosensors had good reproducibility of preparation), but it was more complicated, drop coating was easier and led to formation of a bulk of particles; thus, biosensors had bigger sensitivity but worse reproducibility of preparation. Urease was immobilized onto transducers modified with particles by physical adsorption. Analytical characteristics of the obtained biosensors for determination of urea (calibration curves, sensitivity, limit of detection, linear concentration range, noise of responses, reproducibility of signal during a day, and operational stability during 3 days) were compared. Biosensors with all three particles deposited by spin coating showed similar characteristics; however, silicalite was a bit more effective. Biosensors based on nickel transducers modified by drop coating had better characteristics in comparison with modification by spin coating (except reproducibility of preparation). Transducers with gold electrodes showed best characteristics while creating biosensors, platinum electrodes were slightly inferior to them, and nickel electrodes were the worst.

Improved electron injection in spin coated Alq3 incorporated ZnO thin film in the device for solution processed OLEDs

NASA Astrophysics Data System (ADS)

Dasi, Gnyaneshwar; Ramarajan, R.; Thangaraju, Kuppusamy

2018-04-01

We deposit tris-(8-hydroxyquinoline)aluminum (Alq3) incorporated zinc oxide (ZnO) thin films by spin coating method under the normal ambient. It showed the higher transmittance (90% at 550 nm) when compared to that (80% at 550 nm) of spin coated pure ZnO film. SEM studies show that the Alq3 incorporation in ZnO film also enhances the formation of small sized particles arranged in the network of wrinkles on the surface. XRD reveals the improved crystalline properties upon Alq3 inclusion. We fabricate the electron-only devices (EODs) with the structure of ITO/spin coated ZnO:Alq3 as ETL/Alq3 interlayer/LiF/Al. The device showed the higher electron current density of 2.75 mA/cm2 at 12V when compared to that (0.82 mA/cm2 at 12V) of the device using pure ZnO ETL. The device results show that it will be useful to fabricate the low-cost solution processed OLEDs for future lighting and display applications.

The effect of processing on the surface physical stability of amorphous solid dispersions.

PubMed

Yang, Ziyi; Nollenberger, Kathrin; Albers, Jessica; Moffat, Jonathan; Craig, Duncan; Qi, Sheng

2014-11-01

The focus of this study was to investigate the effect of processing on the surface crystallization of amorphous molecular dispersions and gain insight into the mechanisms underpinning this effect. The model systems, amorphous molecular dispersions of felodipine-EUDRAGIT® E PO, were processed both using spin coating (an ultra-fast solvent evaporation based method) and hot melt extrusion (HME) (a melting based method). Amorphous solid dispersions with drug loadings of 10-90% (w/w) were obtained by both processing methods. Samples were stored under 75% RH/room temperatures for up to 10months. Surface crystallization was observed shortly after preparation for the HME samples with high drug loadings (50-90%). Surface crystallization was characterized by powder X-ray diffraction (PXRD), ATR-FTIR spectroscopy and imaging techniques (SEM, AFM and localized thermal analysis). Spin coated molecular dispersions showed significantly higher surface physical stability than hot melt extruded samples. For both systems, the progress of the surface crystal growth followed zero order kinetics on aging. Drug enrichment at the surfaces of HME samples on aging was observed, which may contribute to surface crystallization of amorphous molecular dispersions. In conclusion it was found the amorphous molecular dispersions prepared by spin coating had a significantly higher surface physical stability than the corresponding HME samples, which may be attributed to the increased process-related apparent drug-polymer solubility and reduced molecular mobility due to the quenching effect caused by the rapid solvent evaporation in spin coating. Copyright © 2014 Elsevier B.V. All rights reserved.

Mesoporous silica film from a solution containing a surfactant and methods of making same

DOEpatents

Liu, Jun [West Richland, WA; Domansky, Karel [Cambridge, MA; Li, Xiaohong [Richland, WA; Fryxell, Glen E [Kennewick, WA; Baskaran, Suresh [Kennewick, WA; Kohler, Nathan J [Richland, WA; Thevuthasan, Suntharampillai [Kennewick, WA; Coyle, Christopher A [Richland, WA; Birnbaum, Jerome C [Richland, WA

2001-12-11

The present invention is a mesoporous silica film having a low dielectric constant and method of making having the steps of combining a surfactant in a silica precursor solution, spin-coating a film from this solution mixture, forming a partially hydroxylated mesoporous film, and dehydroxylating the hydroxylated film to obtain the mesoporous film. It is advantageous that the small polyoxyethylene ether surfactants used in spin-coated films as described in the present invention will result in fine pores smaller on average than about 20 nm. The resulting mesoporous film has a dielectric constant less than 3, which is stable in moist air with a specific humidity. The present invention provides a method for superior control of film thickness and thickness uniformity over a coated wafer, and films with low dielectric constant.

Heterofunctional nanosheet controlling cell adhesion properties by collagen coating.

PubMed

Niwa, Daisuke; Fujie, Toshinori; Lang, Thorsten; Goda, Nobuhito; Takeoka, Shinji

2012-08-01

Recently, biomaterials have been widely used in a variety of medical applications. We previously reported that a poly-l-lactic acid (PLLA) nanosheet shows anti-adhesive properties and constitutes a useful biomaterial for preventing unwanted wound adhesion in surgical operations. In this article, we examine whether the PLLA nanosheet can be specifically modified with biomacromolecules on one surface only. Such an approach would endow each side of the nanosheet with discrete functions, that is anti-adhesive and pro-healing properties. We fabricated two distinct PLLA nanosheets: (i) collagen cast on the surface of a PLLA nanosheet (Col-Cast-PLLA) and (ii) collagen spin-coated on the nanosheet (Col-Spin-PLLA). In the Col-Spin-PLLA nanosheet, the collagen layer had a thickness of 5-10 nm on the PLLA surface and displayed increased hydrophilicity compared to both PLLA and Col-Cast-PLLA nanosheets. In addition, atomic force microscopy showed disorganized collagen fibril formation on the PLLA layer when covered using the spin-coating method, while apparent bundle formations of collagen were formed in the Col-Cast-PLLA nanosheet. The Col-Spin-PLLA nanosheet provided a microenvironment for cells to adhere and spread. By contrast, the Col-Cast-PLLA nanosheet displayed reduced cell adhesion compared to the Col-Spin-PLLA nanosheet. Consistent with these findings, immunocytochemical analysis clearly showed fine networks of actin filaments in cells cultured on the Col-Spin-PLLA, but not the Col-Cast-PLLA nanosheet. Therefore, the Col-Spin-PLLA nanosheet was shown to be more suitable for acting as a scaffold. In conclusion, we have succeeded in developing a heterofunctional nanosheet comprising a collagen modified side, which has the ability to rapidly adhere cells, and an unmodified side, which acts as an adhesion barrier, by using a spin-coating technique.

Synthesis and optical characterization of ternary chalcogenide Cu3BiS3 thin film by spin coating

NASA Astrophysics Data System (ADS)

Rawal, Neha; Hadi, Mohammed Kamal; Modi, B. P.

2017-05-01

In this work, ternary Chalcogenide Cu3BiS3(CBS) thin films have been prepared and modified by using spin coating technique. Lucratively, spin coating technique is easy going and simple though it hasn't given an enclosure and extensive focus of researches for Cu3BiS3 thin films formation. The surface smoothness and the homogeneity of the obtained thin films have been optimized throughout varying the annealing temperature, concentration and rotation speed. It had been found that as prepared films the value of the energy band gap is 1.4 eV, the absorption coefficient 105 cm-1. Each values of the EBG (Energy Band Gap) and AC (Absorption coefficient) was found in quite agreement with the published work of CBS thin film formation by other methods as CBD, dip coating etc. It signifies that Cu3BiS3 films can be used as an absorber layer for thin film solar cell.

CdS/CdSe quantum dot shell decorated vertical ZnO nanowire arrays by spin-coating-based SILAR for photoelectrochemical cells and quantum-dot-sensitized solar cells.

PubMed

Zhang, Ran; Luo, Qiu-Ping; Chen, Hong-Yan; Yu, Xiao-Yun; Kuang, Dai-Bin; Su, Cheng-Yong

2012-04-23

A CdS/CdSe composite shell is assembled onto the surface of ZnO nanowire arrays with a simple spin-coating-based successive ionic layer adsorption and reaction method. The as-prepared photoelectrode exhibit a high photocurrent density in photoelectrochemical cells and also generates good power conversion efficiency in quantum-dot-sensitized solar cells. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rugged spin-polarized electron sources based on negative electron affinity GaAs photocathode with robust Cs2Te coating

NASA Astrophysics Data System (ADS)

Bae, Jai Kwan; Cultrera, Luca; DiGiacomo, Philip; Bazarov, Ivan

2018-04-01

Photocathodes capable of providing high intensity and highly spin-polarized electron beams with long operational lifetimes are of great interest for the next generation nuclear physics facilities like Electron Ion Colliders. We report on GaAs photocathodes activated by Cs2Te, a material well known for its robustness. GaAs activated by Cs2Te forms Negative Electron Affinity, and the lifetime for extracted charge is improved by a factor of 5 compared to that of GaAs activated by Cs and O2. The spin polarization of photoelectrons was measured using a Mott polarimeter and found to be independent from the activation method, thereby shifting the paradigm on spin-polarized electron sources employing photocathodes with robust coatings.

Resistivity behavior of optimized PbTiO3 thin films prepared by spin coating method

NASA Astrophysics Data System (ADS)

Nurbaya, Z.; Wahid, M. H.; Rozana, M. D.; Alrokayan, S. A. H.; Khan, H. A.; Rusop, M.

2018-05-01

Th is study presents the resistivity behavior of PbTiO3 thin films which were prepared towards metal-insulator-metal capacitor device fabrication. The PbTiO3 thin films were prepared through sol-gel spin coating method that involved various deposition parameters that is (1) different molar concentration of PbTiO3 solutions, (2) various additional PbAc-content in PbTiO3 solutions, and (3) various annealing temperature on PbTiO3 thin films. Hence, an electrical measurement of current versus voltage was done to determine the resistivity behavior of PbTiO3 thin films.

Efficiency enhancement of polymer solar cells by applying poly(vinylpyrrolidone) as a cathode buffer layer via spin coating or self-assembly.

PubMed

Wang, Haitao; Zhang, Wenfeng; Xu, Chenhui; Bi, Xianghong; Chen, Boxue; Yang, Shangfeng

2013-01-01

A non-conjugated polymer poly(vinylpyrrolidone) (PVP) was applied as a new cathode buffer layer in P3HT:PCBM bulk heterojunction polymer solar cells (BHJ-PSCs), by means of either spin coating or self-assembly, resulting in significant efficiency enhancement. For the case of incorporation of PVP by spin coating, power conversion efficiency (PCE) of the ITO/PEDOT:PSS/P3HT:PCBM/PVP/Al BHJ-PSC device (3.90%) is enhanced by 29% under the optimum PVP spin-coating speed of 3000 rpm, which leads to the optimum thickness of PVP layer of ~3 nm. Such an efficiency enhancement is found to be primarily due to the increase of the short-circuit current (J(sc)) (31% enhancement), suggesting that the charge collection increases upon the incorporation of a PVP cathode buffer layer, which originates from the conjunct effects of the formation of a dipole layer between P3HT:PCBM active layer and Al electrodes, the chemical reactions of PVP molecules with Al atoms, and the increase of the roughness of the top Al film. Incorporation of PVP layer by doping PVP directly into the P3HT:PCBM active layer leads to an enhancement of PCE by 13% under the optimum PVP doping ratio of 3%, and this is interpreted by the migration of PVP molecules to the surface of the active layer via self-assembly, resulting in the formation of the PVP cathode buffer layer. While the formation of the PVP cathode buffer layer is fulfilled by both fabrication methods (spin coating and self-assembly), the dependence of the enhancement of the device performance on the thickness of the PVP cathode buffer layer formed by self-assembly or spin coating is different, because of the different aggregation microstructures of the PVP interlayer.

Advanced Fabrication Method for the Preparation of MOF Thin Films: Liquid-Phase Epitaxy Approach Meets Spin Coating Method.

PubMed

Chernikova, Valeriya; Shekhah, Osama; Eddaoudi, Mohamed

2016-08-10

Here, we report a new and advanced method for the fabrication of highly oriented/polycrystalline metal-organic framework (MOF) thin films. Building on the attractive features of the liquid-phase epitaxy (LPE) approach, a facile spin coating method was implemented to generate MOF thin films in a high-throughput fashion. Advantageously, this approach offers a great prospective to cost-effectively construct thin-films with a significantly shortened preparation time and a lessened chemicals and solvents consumption, as compared to the conventional LPE-process. Certainly, this new spin-coating approach has been implemented successfully to construct various MOF thin films, ranging in thickness from a few micrometers down to the nanometer scale, spanning 2-D and 3-D benchmark MOF materials including Cu2(bdc)2·xH2O, Zn2(bdc)2·xH2O, HKUST-1, and ZIF-8. This method was appraised and proved effective on a variety of substrates comprising functionalized gold, silicon, glass, porous stainless steel, and aluminum oxide. The facile, high-throughput and cost-effective nature of this approach, coupled with the successful thin film growth and substrate versatility, represents the next generation of methods for MOF thin film fabrication. Therefore, paving the way for these unique MOF materials to address a wide range of challenges in the areas of sensing devices and membrane technology.

Spin coating apparatus

DOEpatents

Torczynski, John R.

2000-01-01

A spin coating apparatus requires less cleanroom air flow than prior spin coating apparatus to minimize cleanroom contamination. A shaped exhaust duct from the spin coater maintains process quality while requiring reduced cleanroom air flow. The exhaust duct can decrease in cross section as it extends from the wafer, minimizing eddy formation. The exhaust duct can conform to entrainment streamlines to minimize eddy formation and reduce interprocess contamination at minimal cleanroom air flow rates.

In vivo evaluation of CaO-SiO2-P2O5-B2O3 glass-ceramics coating on Steinman pins.

PubMed

Lee, Jae Hyup; Hong, Kug Sun; Baek, Hae-Ri; Seo, Jun-Hyuk; Lee, Kyung Mee; Ryu, Hyun-Seung; Lee, Hyun-Kyung

2013-07-01

Surface coating using ceramics improves the bone bonding strength of an implant. We questioned whether a new type of glass-ceramics (BGS-7) coating (CaO-SiO2 -P2 O5 -B2 O3 ) would improve the osseointegration of Steinman pins (S-pins) both biomechanically and histomorphometrically. An in vivo study was performed using rabbits by inserting three S-pins into each iliac bone. The pins were 2.2-mm S-pins with a coating of 30-μm-thick BGS-7 and 550-nm-thick hydroxyapatite (HA), as opposed to an S-pin without coating. A tensile strength test and histomorphometrical evaluation was performed. In the 2-week group, the BGS-7 implant showed a significantly higher tensile strength than the S-pin. In the 4- and 8-week groups, the BGS-7 implants had significantly higher tensile strengths than the S-pins and HA implants. The histomorphometrical study revealed that the BGS-7 implant had a significantly higher contact ratio than the S-pin and HA implants in the 4-week group. The biomechanical and histomorphometrical tests showed that the BGS-7 coating had superior bone bonding properties than the groups without the coating from the initial stage of insertion. The BGS-7 coating of an S-pin will enhance the bone bonding strength, and there might also be an advantage in human bone bonding. © 2013, Copyright the Authors. Artificial Organs © 2013, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Highly-transparent multi-layered spin-coated silk fibroin film

NASA Astrophysics Data System (ADS)

Wasapinyokul, Kamol; Kaewpirom, Supranee; Chuwongin, Santhad; Boonsang, Siridech

2017-10-01

In this study, the silk fibroin films with different numbers of layers were fabricated by the spin-coating method and their optical transmittances were observed. The process to synthesise the silk fibroin solution was explained - starting from the silk cocoon until the silk-fibroin solution, approximately 7.5% concentration wt/vol, was obtained. The solution was spin-coated onto clean glass substrates to fabricate samples. Totally 10 samples with different numbers of layers, from 1 to 5 layers, were obtained. All samples can be separated into two groups: those left dried at room temperature after spin-coating and those heated at 60°C. They were then measured for their transmittance over the visible-to-near-infrared region. All samples exhibited the high transmittance where the values were at 95% and 98%, for the samples at room temperature and those at 60°C, respectively. This was believed to be due to the heating effect that caused the silk fibroin to arrange itself after being heated, hence the higher transmittance. These high transmittances were maintained regardless of the number of layers and length of heating time. Results from this study could be used to fabricate a silk fibroin film with high optical transmittance and adjustable other properties.

Enhanced Ex Vivo Expansion of Human Hematopoietic Progenitors on Native and Spin Coated Acellular Matrices Prepared from Bone Marrow Stromal Cells

PubMed Central

Wasnik, Samiksha; Kantipudi, Suma; Kirkland, Mark A.; Pande, Gopal

2016-01-01

The extracellular microenvironment in bone marrow (BM) is known to regulate the growth and differentiation of hematopoietic stem and progenitor cells (HSPC). We have developed cell-free matrices from a BM stromal cell line (HS-5), which can be used as substrates either in native form or as tissue engineered coatings, for the enhanced ex vivo expansion of umbilical cord blood (UCB) derived HSPC. The physicochemical properties (surface roughness, thickness, and uniformity) of native and spin coated acellular matrices (ACM) were studied using scanning and atomic force microscopy (SEM and AFM). Lineage-specific expansion of HSPC, grown on these substrates, was evaluated by immunophenotypic (flow cytometry) and functional (colony forming) assays. Our results show that the most efficient expansion of lineage-specific HSPC occurred on spin coated ACM. Our method provides an improved protocol for ex vivo HSPC expansion and it offers a system to study the in vivo roles of specific molecules in the hematopoietic niche that influence HSPC expansion. PMID:26981135

Optimization of rotational speed for growing BaFe12O19 thin films using spin coating

NASA Astrophysics Data System (ADS)

Budiawanti, S.; Soegijono, B.; Mudzakir, I.; Suharno, Fadillah, L.

2017-07-01

Barium ferrite (BaFe12O19, BaM) thin films were fabricated by the spin coating of precursors obtained by using a sol-gel method. The effects of the rotational speed on the spin-coating process for growing a BaM thin film were investigated in this study. Coated films were heat-deposited at different rotational speeds ranging from 2000 to 4000 rpm, while the number of layers was set to nine. Further, the effect of the number of layers on the growth of BaM thin films was discussed. For this purpose, we take the layers number 1 to 12 and take the constant rotational speed of 3000 rpm. All the film were characterized using X-Ray diffraction, Scanning Electron microscope, and Energy-dispersive X-Ray spectroscopy and Vibrating Sample Magnetometer. It was found that by increasing the rotational speed the amount of material deposited on the Si substrate decreased. The measured grain size of the BaM thin film was nearly similar for three three different rotational speeds. However, the grain size was found to increase the number of layers.

Bidisperse silica nanoparticles close-packed monolayer on silicon substrate by three step spin method

NASA Astrophysics Data System (ADS)

Khanna, Sakshum; Marathey, Priyanka; Utsav, Chaliawala, Harsh; Mukhopadhyay, Indrajit

2018-05-01

We present the studies on the structural properties of monolayer Bidisperse silica (SiO2) nanoparticles (BDS) on Silicon (Si-100) substrate using spin coating technique. The Bidisperse silica nanoparticle was synthesised by the modified sol-gel process. Nanoparticles on the substrate are generally assembled in non-close/close-packed monolayer (CPM) form. The CPM form is obtained by depositing the colloidal suspension onto the silicon substrate using complex techniques. Here we report an effective method for forming a monolayer of bidisperse silica nanoparticle by three step spin coating technique. The samples were prepared by mixing the monodisperse solutions of different particles size 40 and 100 nm diameters. The bidisperse silica nanoparticles were self-assembled on the silicon substrate forming a close-packed monolayer film. The scanning electron microscope images of bidisperse films provided in-depth film structure of the film. The maximum surface coverage obtained was around 70-80%.

Fabrication process for polymer PLC platforms with V-grooves for passive alignment

NASA Astrophysics Data System (ADS)

Park, Suntak; Lee, Jong-Moo; Ahn, Joon Tae; Baek, Yong-Soon

2005-12-01

A method for polymer planar lightwave circuit (PLC) devices fabricated on a substrate with V-grooves is developed for passive alignment of an optical fiber to a polymer waveguide. In order to minimize thickness nonuniformity of polymer layers caused by the V-grooves, dry film resist (DFR) is used. The V-grooves are covered with the DFR before the polymer layers are spin-coated on the substrate. The DFR prevents the polymer from being filled in the V-grooves as well as from being spin-coated nonuniformly on the substrate. This process provides a simple and cost-effective fabrication method of polymer PLCs or platforms for passive alignment.

Synthesis and characterization of transparent conductive zinc oxide thin films by sol-gel spin coating method

NASA Astrophysics Data System (ADS)

Winarski, David

Zinc oxide has been given much attention recently as it is promising for various semiconductor device applications. ZnO has a direct band gap of 3.3 eV, high exciton binding energy of 60 meV and can exist in various bulk powder and thin film forms for different applications. ZnO is naturally n-type with various structural defects, which sparks further investigation into the material properties. Although there are many potential applications for this ZnO, an overall lack of understand and control of intrinsic defects has proven difficult to obtain consistent, repeatable results. This work studies both synthesis and characterization of zinc oxide in an effort to produce high quality transparent conductive oxides. The sol-gel spin coating method was used to obtain highly transparent ZnO thin films with high UV absorbance. This research develops a new more consistent method for synthesis of these thin films, providing insight for maintaining quality control for each step in the procedure. A sol-gel spin coating technique is optimized, yielding highly transparent polycrystalline ZnO thin films with tunable electrical properties. Annealing treatment in hydrogen and zinc atmospheres is researched in an effort to increase electrical conductivity and better understand intrinsic properties of the material. These treatment have shown significant effects on the properties of ZnO. Characterization of doped and undoped ZnO synthesized by the sol-gel spin coating method was carried out using scanning electron microscopy, UV-Visible range absorbance, X-ray diffraction, and the Hall Effect. Treatment in hydrogen shows an overall decrease in the number of crystal phases and visible absorbance while zinc seems to have the opposite effect. The Hall Effect has shown that both annealing environments increase the n-type conductivity, yielding a ZnO thin film with a carrier concentration as high as 3.001 x 1021 cm-3.

Light-driven 3D droplet manipulation on flexible optoelectrowetting devices fabricated by a simple spin-coating method.

PubMed

Jiang, Dongyue; Park, Sung-Yong

2016-05-21

Technical advances in electrowetting-on-dielectric (EWOD) over the past few years have extended our attraction to three-dimensional (3D) devices capable of providing more flexibility and functionality with larger volumetric capacity than conventional 2D planar ones. However, typical 3D EWOD devices require complex and expensive fabrication processes for patterning and wiring of pixelated electrodes that also restrict the minimum droplet size to be manipulated. Here, we present a flexible single-sided continuous optoelectrowetting (SCOEW) device which is not only fabricated by a spin-coating method without the need for patterning and wiring processes, but also enables light-driven 3D droplet manipulations. To provide photoconductive properties, previous optoelectrowetting (OEW) devices have used amorphous silicon (a-Si) typically fabricated through high-temperature processes over 300 °C such as CVD or PECVD. However, most of the commercially-available flexible substrates such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) experience serious thermal deformation under such high-temperature processes. Because of this compatibility issue of conventional OEW devices with flexible substrates, light-driven 3D droplet manipulations have not yet been demonstrated on flexible substrates. Our study overcomes this compatibility issue by using a polymer-based photoconductive material, titanium oxide phthalocyanine (TiOPc) and thus SCOEW devices can be simply fabricated on flexible substrates through a low-cost, spin-coating method. In this paper, analytical studies were conducted to understand the effects of light patterns on static contact angles and EWOD forces. For experimental validations of our study, flexible SCOEW devices were successfully fabricated through the TiOPc-based spin-coating method and light-driven droplet manipulations (e.g. transportation, merging, and splitting) have been demonstrated on various 3D terrains such as inclined, vertical, upside-down, and curved surfaces. Our flexible SCOEW technology offers the benefits of device simplicity, flexibility, and functionality over conventional EWOD and OEW devices by enabling optical droplet manipulations on a 3D featureless surface.

Manufacturing PDMS micro lens array using spin coating under a multiphase system

NASA Astrophysics Data System (ADS)

Sun, Rongrong; Yang, Hanry; Rock, D. Mitchell; Danaei, Roozbeh; Panat, Rahul; Kessler, Michael R.; Li, Lei

2017-05-01

The development of micro lens arrays has garnered much interest due to increased demand of miniaturized systems. Traditional methods for manufacturing micro lens arrays have several shortcomings. For example, they require expensive facilities and long lead time, and traditional lens materials (i.e. glass) are typically heavy, costly and difficult to manufacture. In this paper, we explore a method for manufacturing a polydimethylsiloxane (PDMS) micro lens array using a simple spin coating technique. The micro lens array, formed under an interfacial tension dominated system, and the influence of material properties and process parameters on the fabricated lens shape are examined. The lenses fabricated using this method show comparable optical properties—including surface finish and image quality—with a reduced cost and manufacturing lead time.

Influence of pH on optoelectronic properties of zinc sulphide thin films prepared using hydrothermal and spin coating method

NASA Astrophysics Data System (ADS)

Choudapur, V. H.; Bennal, A. S.; Raju, A. B.

2018-04-01

The ZnS nanomaterial is synthesized by hydrothermal method under optimized conditions using Zinc acetate and sodium sulphide as precursors. The Zinc Sulphide thin films are obtained by simple spin coating method with high optical transmittance. The prepared thin films are adhesive and uniform. The x-ray diffraction analysis showed that the films are polycrystalline in cubic phase with the preferred orientation along (111) direction. Current-voltage curves were recorded at room temperature using Keithley 617 programmable electrometer and conductivity is calculated for the film coated on ITO by two probe method. The pH of the solution is varied by using ammonia and hydrochloric acid. The comparative studies of effect of pH on the morphology, crystallanity and optoelectronic properties of the films are studied. It is observed that the pH of the solution has large influence on optoelectronic properties. The thin film prepared with neutral pH has higher crystallanity, bandgap and conductivity as compared to the samples prepared in acidic or basic solutions.

A comparative study on the morphology of P3HT:PCBM solar cells with the addition of Fe3O4 nanoparticles by spin and rod coating methods

NASA Astrophysics Data System (ADS)

Zhang, Wenluan; Nguyen, Ngoc A.; Murray, Roy; Xin, Jiyuan; Mackay, Michael E.

2017-09-01

Our previous study presented up to 20% power conversion efficiency (PCE) enhancement of poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) solar cells under the Fe3O4 nanoparticles (NPs) self-assembly (SA) effect by spin coating. Fe3O4 NPs (about 11 nm hydrodynamic diameter) form a thin layer at the top interface of the light absorbing active layer, which results in the generation of PCBM rich region improving the charge transport (Zhang et al. Sol Energ Mat Sol C 160:126-133, 2017). In order to investigate the feasibility of this Fe3O4 NPs SA effect under large-scale production condition, a smooth rod was implemented to mimic roll-to-roll coating technique and yield active layers having about the same thickness as the spin-coated ones. Small angle neutron scattering and grazing incidence X-ray diffraction were employed finding out similar morphologies of the active layers by these two coating techniques. However, rod-coated solar cell's PCE decreases with the addition of Fe3O4 NPs compared with the one without them. This is because PCBM rich region is not created at the top interface of the active layer due to the absence of Fe3O4 NPs, which is attributed to the weak convective flow and low diffusion rate. Moreover, in the rod-coated solar cells, the presence of Fe3O4 NPs causes decrease in P3HT crystallinity, thus the charge transport and the device performance. Our study confirms the role of spin coating in the Fe3O4 NPs SA effect and enables researchers to explore this finding in other polymer nanocomposite systems.

A flexible thermoresponsive cell culture substrate for direct transfer of keratinocyte cell sheets.

PubMed

Praveen, Wulligundam; Madathil, Bernadette K; Sajin Raj, R S; Kumary, T V; Anil Kumar, P R

2017-10-25

Most cell sheet engineering systems require a support or carrier to handle the harvested cell sheets. In this study, polyethylene terephthalate-based overhead projection transparency sheets (OHPS) were subjected to surface hydrolysis by alkali treatment to increase pliability and hydrophilicity and enable poly(N-isopropylacrylamide-co-glycidylmethacrylate) copolymer (NGMA) coating to impart thermoresponsiveness. NGMA was applied on the modified OHPS by the technique of spin coating using an indigenously designed spin coater. The spin coating had the advantage of using low volumes of the polymer and a reduced coating time. The surface chemistry and thermoresponsive coating was analyzed by Fourier transform infrared spectroscopy and water contact angle. Human keratinocyte cells were cultured on the spin coated surface and scaffold-free cell sheets were successfully harvested by simple variation of temperature. These cell sheets were found to be viable, exhibited epithelial characteristic and cell-cell contact as confirmed by positive immunostaining for ZO-1. The integrity and morphology of the cell sheet was confirmed by stereomicroscopy and E-SEM. These results highlight the potential of the NGMA spin coated modified OHPS to serve as a thermoresponsive culture surface-cum-flexible transfer tool.

Measurement of spin-flip probabilities for ultracold neutrons interacting with nickel phosphorus coated surfaces

DOE PAGES

Tang, Zhaowen; Adamek, Evan Robert; Brandt, Aaron; ...

2016-04-26

In this paper, we report a measurement of the spin-flip probabilities for ultracold neutrons interacting with surfaces coated with nickel phosphorus. For 50 μm thick nickel phosphorus coated on stainless steel, the spin-flip probability per bounce was found to be β NiP on SS = (3.3 +1.8, -5.6) X 10 -6. For 50 μm thick nickel phosphorus coated on aluminum, the spin-flip probability per bounce was found to be β NiP on Al = (3.6 +2.1, -5.9) X 10 -6. For the copper guide used as reference, the spin flip probability per bounce was found to be β Cu =more » (6.7 + 5.0, -2.5) X 10 -6. The results on the nickel phosphorus-coated surfaces may be interpreted as upper limits, yielding β NiP on SS < 6.2 X 10 -6 (90% C.L.) and β NiP on Al < 7.0 X 10 -6 (90% C.L.) for 50 μm thick nickel phosphorus coated on stainless steel and 50 μm thick nickel phosphorus coated on aluminum, respectively. Finally, nickel phosphorus coated stainless steel or aluminum provides a solution when low-cost, mechanically robust, and non-depolarizing UCN guides with a high Fermi potential are needed.« less

Free Electron Laser Induced Forward Transfer Method of Biomaterial for Marking

NASA Astrophysics Data System (ADS)

Suzuki, Kaoru

Biomaterial, such as chitosan, poly lactic acid, etc., containing fluorescence agent was deposited onto biology hard tissue, such as teeth, fingernail of dog or cat, or sapphire substrate by free electron laser induced forward transfer method for direct write marking. Spin-coated biomaterial with fluorescence agent of rhodamin-6G or zinc phthalochyamine target on sapphire plate was ablated by free electron laser (resonance absorption wavelength of biomaterial : 3380 nm). The influence of the spin-coating film-forming temperature on hardness and adhesion strength of biomaterial is particularly studied. Effect of resonance excitation of biomaterial target by turning free electron laser was discussed to damage of biomaterial, rhodamin-6G or zinc phtarochyamine for direct write marking

Using mixed solvent and changing spin-coating parameters to increase the efficiency and lifetime of organic solar cells.

PubMed

Tsai, Yu Sheng; Chu, Wei-Ping; Tang, Rong-Ming; Juang, Fuh-Shyang; Chang, Ming-Hua; Liu, Mark O; Hsieh, Tsung-Eong

2008-10-01

The derivative of C60, i.e., PCBM, and P3HT (3-hexylthiophene) were dissolved in chloroform:dichlorobenzene mixed solvent, then spin-coated as the active layer for organic solar cells (OSC). The experimental parameters were studied carefully to obtain the optimum power conversion efficiency (PCE), including the solvent mixing ratio, spin-coating speed, annealing conditions for the active layer, etc. The OSC devices were packaged with glass and a newly developed UV-glue to improve the lifetime and PCE. Dichlorobenzene solvent has great effect upon the PCE. Changing the spin-coating speed and increasing the number of steps increased the PCE apparently to 1.4%.

Magnetic properties of LCMO deposited films

NASA Astrophysics Data System (ADS)

Park, Seung-Iel; Jeong, Kwang Ho; Cho, Young Suk; Kim, Chul Sung

2002-04-01

La-Ca-Mn-O films were deposited with various thickness (500, 1000 and 1500°C) by RF-magnetron sputtering at 700°C and by the spin coating of sol-gel method at 400°C on LaAlO 3(1 0 0) and Si(1 0 0) single-crystal substrates. The crystal structure and chemical composition of the film grown by RF sputtering method were orthorhombic and La 0.89Ca 0.11MnO 3, respectively, while the film prepared by sol-gel spin coating was cubic with La 0.7Ca 0.3MnO 3. The temperature dependence of the resistance for the film grown by RF sputtering method with the thickness of 1000°C shows that a semiconductor-metal transition occurs at 242 K. The relative maximum magnetoresistance is about 273% at 226 K.

Synthesis and characterization of nanocomposite polymer blend electrolyte thin films by spin-coating method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapi, Sharanappa; Niranjana, M.; Devendrappa, H., E-mail: dehu2010@gmail.com

2016-05-23

Solid Polymer blend electrolytes based on Polyethylene oxide (PEO) and poly vinyl pyrrolidone (PVP) complexed with zinc oxide nanoparticles (ZnO NPs; Synthesized by Co-precipitation method) thin films have prepared at a different weight percent using the spin-coating method. The complexation of the NPs with the polymer blend was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR). The variation in film morphology was examined by polarized optical micrographs (POMs). The thermal behavior of blends was investigated under non-isothermal conditions by differential thermal analyses (DTA). A single glass transition temperature for each blend was observed, which supports the existence ofmore » compatibility of such system. The obtained results represent that the ternary based thin films are prominent materials for battery and optoelectronic device applications.« less

Determination of acrylamide in brewed coffee and coffee powder using polymeric ionic liquid-based sorbent coatings in solid-phase microextraction coupled to gas chromatography-mass spectrometry.

PubMed

Cagliero, Cecilia; Ho, Tien D; Zhang, Cheng; Bicchi, Carlo; Anderson, Jared L

2016-06-03

This study describes a simple and rapid sampling method employing a polymeric ionic liquid (PIL) sorbent coating in direct immersion solid-phase microextraction (SPME) for the trace-level analysis of acrylamide in brewed coffee and coffee powder. The crosslinked PIL sorbent coating demonstrated superior sensitivity in the extraction of acrylamide compared to all commercially available SPME coatings. A spin coating method was developed to evenly distribute the PIL coating on the SPME support and reproducibly produce fibers with a large film thickness. Ninhydrin was employed as a quenching reagent during extraction to inhibit the production of interfering acrylamide. The PIL fiber produced a limit of quantitation for acrylamide of 10μgL(-1) and achieved comparable results to the ISO method in the analysis of six coffee powder samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous spin-coating and solvent annealing: Manipulating the active layer morphology to a power conversion efficiency of 9.6% in polymer solar cells

DOE PAGES

He, Zhicai; Liu, Feng; Wang, Cheng; ...

2015-08-20

Here, we developed a simultaneous spin-coating/solvent-annealing process and demonstrated morphology optimization for PTB7 based organic photovoltaics. This novel processing method enhances the edge-on crystalline content in thin films and induces the formation of weak PCBM aggregates. As a result, the efficiency of polymer solar cells increased from 9.2% to a certified high efficiency of 9.61%, owing to an enhanced short-circuit current (J sc, 18.4 mA cm –2vs. 17. 5 mA cm –2) and an improved fill factor.

Electro-spray deposition of a mesoporous TiO2 charge collection layer: toward large scale and continuous production of high efficiency perovskite solar cells.

PubMed

Kim, Min-cheol; Kim, Byeong Jo; Yoon, Jungjin; Lee, Jin-wook; Suh, Dongchul; Park, Nam-gyu; Choi, Mansoo; Jung, Hyun Suk

2015-12-28

The spin-coating method, which is widely used for thin film device fabrication, is incapable of large-area deposition or being performed continuously. In perovskite hybrid solar cells using CH(3)NH(3)PbI(3) (MAPbI(3)), large-area deposition is essential for their potential use in mass production. Prior to replacing all the spin-coating process for fabrication of perovskite solar cells, herein, a mesoporous TiO(2) electron-collection layer is fabricated by using the electro-spray deposition (ESD) system. Moreover, impedance spectroscopy and transient photocurrent and photovoltage measurements reveal that the electro-sprayed mesoscopic TiO(2) film facilitates charge collection from the perovskite. The series resistance of the perovskite solar cell is also reduced owing to the highly porous nature of, and the low density of point defects in, the film. An optimized power conversion efficiency of 15.11% is achieved under an illumination of 1 sun; this efficiency is higher than that (13.67%) of the perovskite solar cell with the conventional spin-coated TiO(2) films. Furthermore, the large-area coating capability of the ESD process is verified through the coating of uniform 10 × 10 cm(2) TiO(2) films. This study clearly shows that ESD constitutes therefore a viable alternative for the fabrication of high-throughput, large-area perovskite solar cells.

Annealing temperature effect on electrical properties of MEH-PPV thin film via spin coating method

NASA Astrophysics Data System (ADS)

Azhar, N. E. A.; Shariffudin, S. S.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

Organic semiconductor has been discovered in different application devices such as organic light emitting diodes (OLEDs). Poly [2-methoxy-5(2' -ethylhexyloxy)-1, 4-phenylenevinylene), MEH-PPV widely used in this device because its ability to produce a good optical quality films. The MEH-PPV was prepared on glass substrate by spin coating method. The thin film was investigated at different annealing temperatures. The scanning electron micrographs (SEM) revealed that sample annealed at 50°C showed uniformity and less aggregation on morphology polymer thin film. Optical properties showed the intensities of visible emission increased as temperatures increased. The current-voltage (I-V) measurement revealed that the temperature of 50°C showed high conductive and it is suitable for optoelectronic device.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deb, Marwan, E-mail: marwan.deb@ipcms.unistra.fr; Vomir, Mircea; Rehspringer, Jean-Luc

Controlling the magnetization dynamics on the femtosecond timescale is of fundamental importance for integrated opto-spintronic devices. For industrial perspectives, it requires to develop simple growth techniques for obtaining large area magneto-optical materials having a high amplitude ultrafast Faraday or Kerr response. Here we report on optical pump probe studies of light induced spin dynamics in high quality bismuth doped iron garnet polycrystalline film prepared by the spin coating method. We demonstrate an ultrafast non-thermal optical control of the spin dynamics using both circularly and linearly polarized pulses.

Application of graphene oxide in water treatment

NASA Astrophysics Data System (ADS)

Liu, Yongchen

2017-11-01

Graphene oxide has good hydrophilicity and has been tried to use it into thin films for water treatment in recent years. In this paper, the preparation methods of graphene oxide membrane are reviewed, including vacuum suction filtration, spray coating, spin coating, dip coating and the layer by layer method. Secondly, the mechanism of mass transfer of graphene membrane is introduced in detail. The application of the graphene oxide membrane, modified graphene oxide membrane and graphene hybrid membranes were discussed in RO, vaporization, nanofiltration and other aspects. Finally, the development and application of graphene membrane in water treatment were discussed.

Fabrication of a printed capacitive air-gap touch sensor

NASA Astrophysics Data System (ADS)

Lee, Sang Hoon; Seo, Hwiwon; Lee, Sangyoon

2018-05-01

Unlike lithography-based processes, printed electronics does not require etching, which makes it difficult to fabricate electronic devices with an air gap. In this study, we propose a method to fabricate capacitive air-gap touch sensors via printing and coating. First, the bottom electrode was fabricated on a flexible poly(ethylene terephthalate) (PET) substrate using roll-to-roll gravure printing with silver ink. Then poly(dimethylsiloxane) (PDMS) was spin coated to form a sacrificial layer. The top electrode was fabricated on the sacrificial layer by spin coating with a stretchable silver ink. The sensor samples were then put in a tetrabutylammonium (TBAF) bath to generate the air gap by removing the sacrificial layer. The capacitance of the samples was measured for verification, and the results show that the capacitance increases in proportion to the applied force from 0 to 2.5 N.

Ordered alternating binary polymer nanodroplet array by sequential spin dewetting.

PubMed

Bhandaru, Nandini; Das, Anuja; Salunke, Namrata; Mukherjee, Rabibrata

2014-12-10

We report a facile technique for fabricating an ordered array of nearly equal-sized mesoscale polymer droplets of two constituent polymers (polystyrene, PS and poly(methyl methacrylate), PMMA) arranged in an alternating manner on a topographically patterned substrate. The self-organized array of binary polymers is realized by sequential spin dewetting. First, a dilute solution of PMMA is spin-dewetted on a patterned substrate, resulting in an array of isolated PMMA droplets arranged along the substrate grooves due to self-organization during spin coating itself. The sample is then silanized with octadecyltrichlorosilane (OTS), and subsequently, a dilute solution of PS is spin-coated on to it, which also undergoes spin dewetting. The spin-dewetted PS drops having a size nearly equal to the pre-existing PMMA droplets position themselves between two adjacent PMMA drops under appropriate conditions, forming an alternating binary polymer droplet array. The alternating array formation takes place for a narrow range of solution concentration for both the polymers and depends on the geometry of the substrate. The size of the droplets depends on the extent of confinement, and droplets as small as 100 nm can be obtained by this method, on a suitable template. The findings open up the possibility of creating novel surfaces having ordered multimaterial domains with a potential multifunctional capability.

Processing and Characterization of Nanoparticle Coatings for Quartz Crystal Microbalance Measurements

PubMed Central

Torrey, Jessica D.; Kirschling, Teresa L.; Greenlee, Lauren F.

2015-01-01

The quartz-crystal microbalance is a sensitive and versatile tool for measuring adsorption of a variety of compounds (e.g. small molecules, polymers, biomolecules, nanoparticles and cells) to surfaces. While the technique has traditionally been used for measuring adsorption to flat surfaces and thin ridged films, it can also be extended to study adsorption to nanoparticle surfaces when the nanoparticles are fixed to the crystal surface. The sensitivity and accuracy of the measurement depend on the users’ ability to reproducibly prepare a thin uniform nanoparticle coating. This study evaluated four coating techniques, including spin coating, spray coating, drop casting, and electrophoretic deposition, for two unique particle chemistries [nanoscale zero valent iron (nZVI) and titanium dioxide (TiO2)] to produce uniform and reproducible nanoparticle coatings for real-time quartz-crystal microbalance measurements. Uniform TiO2 coatings were produced from a 50 mg/mL methanol suspension via spin coating. Nanoscale zero-valent iron was best applied by spray coating a low concentration 1.0 mg/mL suspended in methanol. The application of multiple coatings, rather than an increase in the suspension concentration, was the best method to increase the mass of nanoparticles on the crystal surface while maintaining coating uniformity. An upper mass threshold was determined to be approximately 96 µg/cm2; above this mass, coatings no longer maintained their uniform rigid characteristic, and a low signal to noise ratio resulted in loss of measurable signal from crystal resonances above the fundamental. PMID:26958434

Surface spins disorder in uncoated and SiO2 coated maghemite nanoparticles

NASA Astrophysics Data System (ADS)

Zeb, F.; Nadeem, K.; Shah, S. Kamran Ali; Kamran, M.; Gul, I. Hussain; Ali, L.

2017-05-01

We studied the surface spins disorder in uncoated and silica (SiO2) coated maghemite (γ-Fe2O3) nanoparticles using temperature and time dependent magnetization. The average crystallite size for SiO2 coated and uncoated nanoparticles was about 12 and 29 nm, respectively. Scanning electron microscopy (SEM) showed that the nanoparticles are spherical in shape and well separated. Temperature scans of zero field cooled (ZFC)/field cooled (FC) magnetization measurements showed lower average blocking temperature (TB) for SiO2 coated maghemite nanoparticles as compared to uncoated nanoparticles. The saturation magnetization (Ms) of SiO2 coated maghemite nanoparticles was also lower than the uncoated nanoparticles and is attributed to smaller average crystallite size of SiO2 coated nanoparticles. For saturation magnetization vs. temperature data, Bloch's law (M(T)= M(0).(1- BTb)) was fitted well for both uncoated and SiO2 coated nanoparticles and yields: B =3×10-7 K-b, b=2.22 and B=0.0127 K-b, b=0.57 for uncoated and SiO2 coated nanoparticles, respectively. Higher value of B for SiO2 coated nanoparticles depicts decrease in exchange coupling due to enhanced surface spins disorder (broken surface bonds) as compared to uncoated nanoparticles. The Bloch's exponent b was decreased for SiO2 coated nanoparticles which is due to their smaller average crystallite size or finite size effects. Furthermore, a sharp increase of coercivity at low temperatures (<25 K) was observed for SiO2 coated nanoparticles which is also due to contribution of increased surface anisotropy or frozen surface spins in these smaller nanoparticles. The FC magnetic relaxation data was fitted to stretched exponential law which revealed slower magnetic relaxation for SiO2 coated nanoparticles. All these measurements revealed smaller average crystallite size and enhanced surface spins disorder in SiO2 coated nanoparticles than in uncoated γ-Fe2O3 nanoparticles.

Infrared wire-grid polarizer with sol-gel antireflection films on both sides

NASA Astrophysics Data System (ADS)

Yamada, Itsunari; Ishihara, Yoshiro

2017-12-01

We fabricated an infrared wire-grid polarizer with the high transverse magnetic (TM) polarization transmittance and high extinction ratio by soft imprint lithography, sol-gel method, and Al shadow coating processes. A zilconia film was coated on Si substrate by using sol-gel method and spin coating method. Then, sol-gel zirconia grating was formed on the back side using imprinting using a silicone mold. The polarizer was produced by depositing Al obliquely on the grating. The TM transmittance of the fabricated element was greater than 80% at a wavelength of 4.8 μm. The sol-gel zilconia films acted as antireflection films. The extinction ratio exceeded 26 dB at its wavelength.

The Effect of Thickness of ZnO Thin Films on Hydrophobic Self-Cleaning Properties

NASA Astrophysics Data System (ADS)

Mufti, N.; Arista, D.; Diantoro, M.; Fuad, A.; Taufiq, A.; Sunaryono

2017-05-01

Glass coating can be conducted by using ZnO-photocatalyst based semiconductor material since it is preeminent in decomposing organics compound and dangerous bacteria which often contaminates the environment. If there are dirt containing organics compound on the glass, the ZnO photocatalyst coat can be applied as self-cleaning, usually called self-cleaning glass. It depends on the coating thickness which can be controlled by setting the speed of spin coating. In this research, the various rotating speeds of spin coating were conducted at 2000 rpm, 3000 rpm, and 4000 rpm to control the thickness. The raw materials used in this research were Zn(CH3COOH)2.2H2O (PA 99,5%), Ethylene glycol, Diethanolamine (PA 99%), Isopropanol Alkohol, Glycerol, and Ashton. Synthesis methods used were sol-gel prior to spin coating technic were applied. The results of the film were characterized by using SEM, XRD, and UV-Spectrophotometer. The crystal structure was analyzed by using Highscore plus and GSAS software, the size crystal was calculated by using Scherrer equation, a contact angle with ImageJ software. It was shown that ZnO thin film had been successfully synthesized with the crystal size around 21 nm up to 26 nm. The absorption value is higher due to the increasing of coat thickness with bandgap ± 3.2 eV. The test result of hydrophobic and hydrophilic characteristics show that all samples of ZnO thin film with the thickness ± 1.050 μm, ± 0.450 μm, ± 0.250 μm can be applied as self-cleaning glass. The best result was gained with the thickness of thin film ± 1.050 μm.

Investigation of Annealing Temperature on Copper Oxide Thin Films Using Sol-Gel Spin Coating Technique

NASA Astrophysics Data System (ADS)

Hashim, H.; Samat, S. F. A.; Shariffudin, S. S.; Saad, P. S. M.

2018-03-01

Copper (II) Oxide or cupric oxide (CuO) is one of the well-known materials studied for thin films applications. This paper was studied on the effect of annealing temperature to CuO thin films using sol-gel method and spin coating technique. The solution was prepared by sol-gel method and the thin films were synthesized at various temperatures from 500°C to 700°C that deposited onto the quartz substrates. After the annealing process, the thin films were uniform and brownish black in colour. The measurements were performed by atomic force microscopy (AFM), surface profiler (SP), two-point probe and Ultraviolet-visible (UV-Vis-NIR) spectrometer. From the optical measurement, the band gap was estimated to be 1.44eV for sample annealed at 550°C.

Two-component spin-coated Ag/CNT composite films based on a silver heterogeneous nucleation mechanism adhesion-enhanced by mechanical interlocking and chemical grafting.

PubMed

Zhang, Yang; Kang, Zhixin; Bessho, Takeshi

2017-03-10

In this paper, a new method for the synthesis of silver carbon nanotube (Ag/CNT) composite films as conductive connection units for flexible electronic devices is presented. This method is about a two-component solution process by spin coating with an after-treatment annealing process. In this method, multi-walled carbon nanotubes (MWCNTs) act as the core of silver heterogeneous nucleation, which can be observed and analyzed by a field-emission scanning electron microscope. With the effects of mechanical interlocking, chemical grafting, and annealing, the interfacial adhesive strength between films and PET sheets was enhanced to 12 N cm -1 . The tensile strength of the Ag/CNT composite films was observed to increase by 38% by adding 5 g l -1 MWCNTs. In the four-probe method, the resistivity of Ag/CNT-5 declined by 78.2% compared with pristine Ag films. The anti-fatigue performance of the Ag/CNT composite films was monitored by cyclic bending deformation and the results revealed that the growth rate of electrical resistance during the deformation was obviously retarded. As for industrial application, this method provides an efficient low-cost way to prepare Ag/CNT composite films and can be further applied to other coating systems.

Effect of the Fabrication Parameters of the Nanosphere Lithography Method on the Properties of the Deposited Au-Ag Nanoparticle Arrays

PubMed Central

Liu, Jing; Chen, Chaoyang; Yang, Guangsong; Chen, Yushan; Yang, Cheng-Fu

2017-01-01

The nanosphere lithography (NSL) method can be developed to deposit the Au-Ag triangle hexagonal nanoparticle arrays for the generation of localized surface plasmon resonance. Previously, we have found that the parameters used to form the NSL masks and the physical methods required to deposit the Au-Ag thin films had large effects on the geometry properties of the nanoparticle arrays. Considering this, the different parameters used to grow the Au-Ag triangle hexagonal nanoparticle arrays were investigated. A single-layer NSL mask was formed by using self-assembly nano-scale polystyrene (PS) nanospheres with an average radius of 265 nm. At first, the concentration of the nano-scale PS nanospheres in the solution was set at 6 wt %. Two coating methods, drop-coating and spin-coating, were used to coat the nano-scale PS nanospheres as a single-layer NSL mask. From the observations of scanning electronic microscopy (SEM), we found that the matrixes of the PS nanosphere masks fabricated by using the drop-coating method were more uniform and exhibited a smaller gap than those fabricated by the spin-coating method. Next, the drop-coating method was used to form the single-layer NSL mask and the concentration of nano-scale PS nanospheres in a solution that was changed from 4 to 10 wt %, for further study. The SEM images showed that when the concentrations of PS nanospheres in the solution were 6 and 8 wt %, the matrixes of the PS nanosphere masks were more uniform than those of 4 and 10 wt %. The effects of the one-side lifting angle of substrates and the vaporization temperature for the solvent of one-layer self-assembly PS nanosphere thin films, were also investigated. Finally, the concentration of the nano-scale PS nanospheres in the solution was set at 8 wt % to form the PS nanosphere masks by the drop-coating method. Three different physical deposition methods, including thermal evaporation, radio-frequency magnetron sputtering, and e-gun deposition, were used to deposit the Au-Ag triangle hexagonal periodic nanoparticle arrays. The SEM images showed that as the single-layer PS nanosphere mask was well controlled, the thermal evaporation could deposit the Au-Ag triangle hexagonal nanoparticle arrays with a higher quality than the other two methods. PMID:28772741

Effect of the Fabrication Parameters of the Nanosphere Lithography Method on the Properties of the Deposited Au-Ag Nanoparticle Arrays.

PubMed

Liu, Jing; Chen, Chaoyang; Yang, Guangsong; Chen, Yushan; Yang, Cheng-Fu

2017-04-03

The nanosphere lithography (NSL) method can be developed to deposit the Au-Ag triangle hexagonal nanoparticle arrays for the generation of localized surface plasmon resonance. Previously, we have found that the parameters used to form the NSL masks and the physical methods required to deposit the Au-Ag thin films had large effects on the geometry properties of the nanoparticle arrays. Considering this, the different parameters used to grow the Au-Ag triangle hexagonal nanoparticle arrays were investigated. A single-layer NSL mask was formed by using self-assembly nano-scale polystyrene (PS) nanospheres with an average radius of 265 nm. At first, the concentration of the nano-scale PS nanospheres in the solution was set at 6 wt %. Two coating methods, drop-coating and spin-coating, were used to coat the nano-scale PS nanospheres as a single-layer NSL mask. From the observations of scanning electronic microscopy (SEM), we found that the matrixes of the PS nanosphere masks fabricated by using the drop-coating method were more uniform and exhibited a smaller gap than those fabricated by the spin-coating method. Next, the drop-coating method was used to form the single-layer NSL mask and the concentration of nano-scale PS nanospheres in a solution that was changed from 4 to 10 wt %, for further study. The SEM images showed that when the concentrations of PS nanospheres in the solution were 6 and 8 wt %, the matrixes of the PS nanosphere masks were more uniform than those of 4 and 10 wt %. The effects of the one-side lifting angle of substrates and the vaporization temperature for the solvent of one-layer self-assembly PS nanosphere thin films, were also investigated. Finally, the concentration of the nano-scale PS nanospheres in the solution was set at 8 wt % to form the PS nanosphere masks by the drop-coating method. Three different physical deposition methods, including thermal evaporation, radio-frequency magnetron sputtering, and e-gun deposition, were used to deposit the Au-Ag triangle hexagonal periodic nanoparticle arrays. The SEM images showed that as the single-layer PS nanosphere mask was well controlled, the thermal evaporation could deposit the Au-Ag triangle hexagonal nanoparticle arrays with a higher quality than the other two methods.

Spin-wave interference in microscopic permalloy tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balhorn, Felix; Nagrodzki, Lukas; Mendach, Stefan

2013-06-03

We present permalloy coated needles which act as spin-wave resonators. The permalloy coated needles were investigated using microwave absorption spectroscopy. Thereby, we found up to three resonant modes which correspond to constructively interfering azimuthal spin waves. The resonant modes are well reproduced in calculations based on an analytical model for the spin-wave dispersion employing periodic boundary conditions. The dependence of the resonance frequencies on the needles' radii and the external magnetic field is demonstrated experimentally.

Constructing a superhydrophobic surface on polydimethylsiloxane via spin coating and vapor-liquid sol-gel process.

PubMed

Peng, Yu-Ting; Lo, Kuo-Feng; Juang, Yi-Je

2010-04-06

In this study, a superhydrophobic surface on polydimethylsiloxane (PDMS) substrate was constructed via the proposed vapor-liquid sol-gel process in conjunction with spin coating of dodecyltrichlorosilane (DTS). Unlike the conventional sol-gel process where the reaction takes place in the liquid phase, layers of silica (SiO(2)) particles were formed through the reaction between the reactant spin-coated on the PDMS surface and vapor of the acid solution. This led to the SiO(2) particles inlaid on the PDMS surface. Followed by subsequent spin coating of DTS solution, the wrinkle-like structure was formed, and the static contact angle of the water droplet on the surface could reach 162 degrees with 2 degrees sliding angle and less than 5 degrees contact angle hysteresis. The effect of layers of SiO(2) particles, concentrations of DTS solution and surface topography on superhydrophobicity of the surface is discussed.

Colloids with high-definition surface structures

PubMed Central

Chen, Hsien-Yeh; Rouillard, Jean-Marie; Gulari, Erdogan; Lahann, Joerg

2007-01-01

Compared with the well equipped arsenal of surface modification methods for flat surfaces, techniques that are applicable to curved, colloidal surfaces are still in their infancy. This technological gap exists because spin-coating techniques used in traditional photolithographic processes are not applicable to the curved surfaces of spherical objects. By replacing spin-coated photoresist with a vapor-deposited, photodefinable polymer coating, we have now fabricated microstructured colloids with a wide range of surface patterns, including asymmetric and chiral surface structures, that so far were typically reserved for flat substrates. This high-throughput method can yield surface-structured colloidal particles at a rate of ≈107 to 108 particles per operator per day. Equipped with spatially defined binding pockets, microstructured colloids can engage in programmable interactions, which can lead to directed self-assembly. The ability to create a wide range of colloids with both simple and complex surface patterns may contribute to the genesis of previously unknown colloidal structures and may have important technological implications in a range of different applications, including photonic and phononic materials or chemical sensors. PMID:17592149

Nondispersive hole transport in a spin-coated dendrimer film measured by the charge-generation-layer time-of-flight method

NASA Astrophysics Data System (ADS)

Markham, Jonathan P. J.; Anthopoulos, Thomas D.; Samuel, Ifor D. W.; Richards, Gary J.; Burn, Paul L.; Im, Chan; Bassler, Heinz

2002-10-01

Measurements of the mobility of a first-generation (G1) bis-fluorene cored dendrimer have been performed on spin-coated samples of 500 nm thickness using the charge-generation-layer time-of-flight (TOF) technique. A 10 nm perylene charge generation layer was excited by the 532 nm line of a Q-switched Nd:YAG laser and the generated carriers swept through the dendrimer film under an applied field. We observe nondispersive hole transport in the dendrimer layer with a room-temperature mobility mu=2.0 x10-4 cm2/V s at a field of 0.55 MV/cm. There is a weak field dependence of the mobility and it increases from mu=1.6 x10-4 cm2/V s at 0.2 MV/cm to mu=3.0 x10-4 cm2/V s at 1.4 MV/cm. These results suggest that the measurement of mobility by TOF in spin-coated samples on thickness scales relevant to organic light-emitting diodes can yield valuable information, and that dendrimers are promising materials for device applications.

Synthesis of nano-sized lithium cobalt oxide via a sol-gel method

NASA Astrophysics Data System (ADS)

Li, Guangfen; Zhang, Jing

2012-07-01

In this study, nano-structured LiCoO2 thin film were synthesized by coupling a sol-gel process with a spin-coating method using polyacrylic acid (PAA) as chelating agent. The optimized conditions for obtaining a better gel formulation and subsequent homogenous dense film were investigated by varying the calcination temperature, the molar mass of PAA, and the precursor's molar ratios of PAA, lithium, and cobalt ions. The gel films on the silicon substrate surfaces were deposited by multi-step spin-coating process for either increasing the density of the gel film or adjusting the quantity of PAA in the film. The gel film was calcined by an optimized two-step heating procedure in order to obtain regular nano-structured LiCoO2 materials. Both atomic force microscopy (AFM) and scanning electron microscopy (SEM) were utilized to analyze the crystalline and the morphology of the films, respectively.

Development of highly-ordered, ferroelectric inverse opal films using sol gel infiltration

NASA Astrophysics Data System (ADS)

Matsuura, N.; Yang, S.; Sun, P.; Ruda, H. E.

2005-07-01

Highly-ordered, ferroelectric, Pb-doped Ba0.7Sr0.3TiO3, inverse opal films were fabricated by spin-coating a sol gel precursor into a polystyrene artificial opal template followed by heat treatment. Thin films of the ferroelectric were independently studied and were shown to exhibit good dielectric properties and high refractive indices. The excellent quality of the final inverse opal film using this spin-coating infiltration method was confirmed by scanning electron microscopy images and the good correspondence between optical reflection data and theoretical simulations. Using this method, the structural and material parameters of the final ferroelectric inverse opal film were easily adjusted by template heating and through repeated infiltrations, without changes in the initial template or precursor. Also, crack-free inverse opal thin films were fabricated over areas comparable to that of the initial crack-free polystyrene template (˜100 by 100 μm2).

A general microchip surface modification approach using a spin-coated polymer resist film doped with hydroxypropyl cellulose.

PubMed

Sun, Xiuhua; Yang, Weichun; Geng, Yanli; Woolley, Adam T

2009-04-07

We have developed a simple and effective method for surface modification of polymer microchips by entrapping hydroxypropyl cellulose (HPC) in a spin-coated thin film on the surface. Poly(methyl methacrylate-8.5-methacrylic acid), a widely available commercial resist formulation, was utilized as a matrix for dissolving HPC and providing adherence to native polymer surfaces. Various amounts of HPC (0.1-2.0%) dissolved in the copolymer and spun on polymer surfaces were evaluated. The modified surfaces were characterized by contact angle measurement, X-ray photoelectron spectroscopy and atomic force microscopy. The developed method was applied on both poly(methyl methacrylate) and cyclic olefin copolymer microchips. A fluorescently labeled myoglobin digest, binary protein mixture, and human serum sample were all separated in these surface-modified polymer microdevices. Our work exhibits an easy and reliable way to achieve favorable biomolecular separation performance in polymer microchips.

A general microchip surface modification approach using a spin-coated polymer resist film doped with hydroxypropyl cellulose

PubMed Central

Sun, Xiuhua; Yang, Weichun; Geng, Yanli; Woolley, Adam T.

2009-01-01

We have developed a simple and effective method for surface modification of polymer microchips by entrapping hydroxypropyl cellulose (HPC) in a spin-coated thin film on the surface. Poly(methyl methacrylate-8.5-methacrylic acid), a widely available commercial resist formulation, was utilized as a matrix for dissolving HPC and providing adherence to native polymer surfaces. Various amounts of HPC (0.1–2.0%) dissolved in the copolymer and spun on polymer surfaces were evaluated. The modified surfaces were characterized by contact angle measurement, X-ray photoelectron spectroscopy and atomic force microscopy. The developed method was applied on both poly(methyl methacrylate) and cyclic olefin copolymer microchips. A fluorescently labeled myoglobin digest, binary protein mixture, and human serum sample were all separated in these surface-modified polymer microdevices. Our work exhibits an easy and reliable way to achieve favorable biomolecular separation performance in polymer microchips. PMID:19294306

Friction modifier using adherent metallic multilayered or mixed element layer conversion coatings

NASA Technical Reports Server (NTRS)

Schramm, Harry F. (Inventor); Defalco, Frank G. (Inventor); Starks, Sr., Lloyd L. (Inventor)

2012-01-01

A process for creating conversion coatings and spin, drawing, and extrusion finishes for surfaces, wherein the conversion coatings and spin, drawing, and extrusion finishes contain potassium, phosphorus, nitrogen, silicon, and one or more non-alkaline metals. The process comprises forming a first aqueous solution of silicate, potassium hydroxide, and ammonium hydroxide; forming a second aqueous solution of water, phosphoric acid, ammonium hydroxide, an alkali metal hydroxide, and one or more non-alkaline metals, and then combining the first solution with the second solution to form a final solution. This final solution forms an anti-friction multi-layer conversion coating or a spin, drawing, and extrusion finish on a surface when applied to the surface, either directly or as an additive in lubricating fluids.

Friction Modifier Using Adherent Metallic Multilayered or Mixed Element Layer Conversion Coatings

NASA Technical Reports Server (NTRS)

Schramm, Harry F. (Inventor); Defalco, Francis G. (Inventor); Starks, Lloyd L., Sr. (Inventor)

2013-01-01

A process for creating conversion coatings and spin, drawing, and extrusion finishes for surfaces, wherein the conversion coatings and spin, drawing, and extrusion finishes contain potassium, phosphorus, nitrogen, and one or more non-alkaline metals and/or one or more metalloids. The process comprises forming an aqueous solution of water, phosphoric acid or sulfuric acid, ammonium hydroxide, an alkali metal hydroxide, and one or more non-alkaline metals and/or one or more metalloids. The aqueous solution forms an anti-friction multilayer conversion and/or mixed element coating or a spin, drawing, and extrusion finish on a surface when applied to the surface, either directly without the use of applied external electromotive force, or as an additive in lubricating fluids.

Nucleation and Crystal Growth of Organic-Inorganic Lead Halide Perovskites under Different Relative Humidity.

PubMed

Gao, Hao; Bao, Chunxiong; Li, Faming; Yu, Tao; Yang, Jie; Zhu, Weidong; Zhou, Xiaoxin; Fu, Gao; Zou, Zhigang

2015-05-06

Organic-inorganic lead halide perovskite compounds are very promising materials for high-efficiency perovskite solar cells. But how to fabricate high-quality perovksite films under controlled humidity conditions is still an important issue due to their sensitivity to moisture. In this study, we investigated the influence of ambient humidity on crystallization and surface morphology of one-step spin-coated perovskite films, as well as the performance of solar cells based on these perovskite films. On the basis of experimental analyses and thin film growth theory, we conclude that the influence of ambient humidity on nucleation at spin-coating stage is quite different from that on crystal growth at annealing stage. At the spin-coating stage, high nucleation density induced by high supersaturation prefers to appear under anhydrous circumstances, resulting in layer growth and high coverage of perovskite films. But at the annealing stage, the modest supersaturation benefits formation of perovskite films with good crystallinity. The films spin-coated under low relative humidity (RH) followed by annealing under high RH show an increase of crystallinity and improved performance of devices. Therefore, a mechanism of fast nucleation followed by modest crystal growth (high supersaturation at spin-coating stage and modest supersaturation at annealing stage) is suggested in the formation of high-quality perovskite films.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aadila, A., E-mail: aadilaazizali@gmail.com; Afaah, A. N.; Asib, N. A. M.

Poly(methyl methacrylate) (PMMA) films were deposited on glass substrate by sol-gel spin-coating method. The films were annealed for 10 minutes in furnace at different annealing temperature of room temperature, 50, 100, 150 and 200 °C. The effect of annealing temperatures to the surface and optical properties of PMMA films spin-coated on the substrate were investigated by Atomic Force Microscope (AFM) and Ultraviolet-Visible (UV-Vis) Spectroscopy. It was observed in AFM analysis all the annealed films show excellent smooth surface with zero roughness. All the samples demonstrate a high transmittance of 80% in UV region as shown in UV-Vis measurement. Highly transparentmore » films indicate the films are good optical properties and could be applied in various optical applications and also in non-linear optics.« less

Separation of Water from Ultralow Sulfur Diesel Using Novel Polymer Nanofiber-Coated Glass Fiber Media.

PubMed

Rajgarhia, Stuti S; Jana, Sadhan C; Chase, George G

2016-08-24

Polymer nanofibers with interpenetrating network (IPN) morphology are used in this work for the development of composite, hydrophobic filter media in conjunction with glass fibers for removal of water droplets from ultralow sulfur diesel (ULSD). The nanofibers are produced from hydrophobic polyvinyl acetate (PVAc) and hydrophilic polyvinylpyrrolidone (PVP) by spinning the polymer solutions using gas jet fiber (GJF) method. The nanofibers coat the individual glass fibers due to polar-polar interactions during the spinning process and render the filter media highly hydrophobic with a water contact angle approaching 150°. The efficiency of the resultant filter media is evaluated in terms of separation of water droplets of average size 20 μm from the suspensions in ULSD.

Sol-gel antireflective spin-coating process for large-size shielding windows

NASA Astrophysics Data System (ADS)

Belleville, Philippe F.; Prene, Philippe; Mennechez, Francoise; Bouigeon, Christian

2002-10-01

The interest of the antireflective coatings applied onto large-area glass components increases everyday for the potential application such as building or shop windows. Today, because of the use of large size components, sol-gel process is a competitive way for antireflective coating mass production. The dip-coating technique commonly used for liquid-deposition, implies a safety hazard due to coating solution handling and storage in the case of large amounts of highly flammable solvent use. On the other hand, spin-coating is a liquid low-consumption technique. Mainly devoted to coat circular small-size substrate, we have developed a spin-coating machine able to coat large-size rectangular windows (up to 1 x 1.7 m2). Both solutions and coating conditions have been optimized to deposit optical layers with accurate and uniform thickness and to highly limit the edge effects. Experimental single layer antireflective coating deposition process onto large-area shielding windows (1000 x 1700 x 20 mm3) is described. Results show that the as-developed process could produce low specular reflection value (down to 1% one side) onto white-glass windows over the visible range (460-750 nm). Low-temperature curing process (120°C) used after sol-gel deposition enables antireflective-coating to withstand abrasion-resistance properties in compliance to US-MIL-C-0675C moderate test.

Scaling behavior of fully spin-coated TFT

NASA Astrophysics Data System (ADS)

Mondal, Sandip; Kumar, Arvind; Rao, K. S. R. Koteswara; Venkataraman, V.

2017-05-01

We studied channel scaling behavior of fully spin coated, low temperature solution processed thin film transistor (TFT) fabricated on p++ - Si (˜1021 cm-3) as bottom gate. The solution processed, spin coated 40 nm thick amorphous Indium Gallium Zinc Oxide (a-IGZO) and 50 nm thick amorphous zirconium di-oxide (a-ZrO2) has been used as channel and low leakage dielectric at 350°C respectively. The channel scaling effect of the TFT with different width/length ratio (W/L= 2.5, 5 and 15) for same channel length (L = 10 μm) has been demonstrated. The lowest threshold voltage (Vth) is 6.25 V for the W/L=50/10. The maximum field effect mobility (μFE) has been found to be 0.123 cm2/Vs from W/L of 50/10 with the drain to source voltage (VD) of 10V and 20V gate to source voltage (VG). We also demonstrated that there is no contact resistance effect on the mobility of the fully sol-gel spin coated TFT.

Analysis and characterization of Cu2CdSnS4 quaternary alloy nanostructures deposited on GaN

NASA Astrophysics Data System (ADS)

Odeh, Ali Abu; Al-Douri, Y.; Ameri, M.; Bouhemadou, A.

2018-06-01

Through using spin coating technique, Cu2CdSnS4 (CCTS) quaternary alloy nanostructures were successfully deposited on GaN substrate using a wide range of spin coating speeds; 1500, 2000, 2500, 3000 and 3500 RPM at annealing temperature 300 °C. The optical properties were investigated through UV-vis which revealed the changing of energy band gap as the spin coating speed increases, in addition, to verify specific models of refractive index and optical dielectric constant. The structural properties were studied by X-ray diffraction which indicated that the number and intensity of the peaks were changed as the spin coating speed changes. The morphological and topographical studies of CCTS were elaborated by field emission-scanning electron microscopy and atomic force microscopy. The obtained results suggest that CCTS nanostructures deposited on GaN substrate are very suitable for optoelectronic applications, that are in accordance with the available theoretical and experimental data.

Contactless laser viscometer for flowing liquid films

NASA Astrophysics Data System (ADS)

Michels, Alexandre F.; Menegotto, Thiago; Grieneisen, Hans-Peter; Horowitz, Flavio

2005-12-01

This work briefly reviews recent progress in interferometric monitoring of spin and of dip coating, from a unified point of view, and its application for contactless viscometry of liquid films. Considering the associated models and measurement uncertainties, the method was validated for both coating processes with oil standards of known viscosities and constant refractive indices. Limitations and perspectives for application of the laser viscometer to liquid films with a varying refractive index are also discussed.

Blade-Cast Nonfullerene Organic Solar Cells in Air with Excellent Morphology, Efficiency, and Stability.

PubMed

Zhang, Lin; Lin, Baojun; Hu, Bo; Xu, Xianbin; Ma, Wei

2018-04-17

Blade-coating serving as a prototype tool for slot-die coating can be very compatible with large-area roll-to-roll coating. Using blade-coating in an ambient environment, an average power conversion efficiency (PCE) of 10.03% is achieved in nonfullerene organic solar cells, which is higher than that of the optimal spin-coated device with a PCE of 9.41%. It is demonstrated that blade-coating can induce a higher degree of molecular packing for both conjugated polymer donors and small-molecular acceptors as it helps to produce a seeding film containing numerous crystal grains, subsequently providing nucleation sites for the residual solution when the motion of the blade exposes a liquid front. Due to this effect, blade-coating can partially replace the role of the additive 1,8-diiodooctane (DIO) and thus achieves the optimized morphology with fewer additives. Moreover, it is found that the blade-coated film with 0.25% DIO possesses not only a smaller domain size but also higher domain purity, suggesting more D/A (donor/acceptor) interfaces and a purer phase domain as compared to the spin-coated film with 1% DIO. Encouragingly, the blade-coated device with less DIO (0.25%) exhibits much better stability than the spin-coated device with 1% DIO, showing excellent prospects. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Printable CIGS thin film solar cells

NASA Astrophysics Data System (ADS)

Fan, Xiaojuan

2014-03-01

Among the various thin film solar cells in the market, CuInGaSe thin film cells have been considered as the most promising alternatives to silicon solar cells because of their high photo-electricity efficiency, reliability, and stability. However, many fabrication of CIGS thin film are based on vacuum processes such as evaporation sputtering techniques which are not cost efficient. This work develops a method using paste or ink liquid spin-coated on glass that would be to conventional ways in terms of cost effective, non-vacuum needed, quick processing. A mixture precursor was prepared by dissolving appropriate amounts of chemicals. After the mixture solution was cooled, a viscous paste prepared and ready for spin-coating process. A slight bluish CIG thin film substrate was then put in a tube furnace with evaporation of metal Se by depositing CdS layer and ZnO nanoparticle thin film coating to a solar cell fabrication. Structure, absorption spectrum, and photo-conversion efficiency for the as-grown CIGS thin film solar cell under study.

Characterization of Antisticking Layers for UV Nanoimprint Lithography Molds with Scanning Probe Microscopy

NASA Astrophysics Data System (ADS)

Masaaki Kurihara,; Sho Hatakeyama,; Noriko Yamada,; Takeya Shimomura,; Takaharu Nagai,; Kouji Yoshida,; Tatsuya Tomita,; Morihisa Hoga,; Naoya Hayashi,; Hiroyuki Ohtani,; Masamichi Fujihira,

2010-06-01

Antisticking layers (ASLs) on UV nanoimprint lithography (UV-NIL) molds were characterized by scanning probe microscopies (SPMs) in addition to macroscopic analyses of work of adhesion and separation force. Local physical properties of the ASLs were measured by atomic force microscopy (AFM) and friction force microscopy (FFM). The behavior of local adhesive forces measured with AFM on several surfaces was consistent with that of work of adhesion obtained from contact angle. The ASLs were coated by two different processes, i.e., one is a vapor-phase process and the other a spin-coating process. The homogeneity of the ASLs prepared by the vapor-phase process was better than that of those prepared by the spin-coating process. In addition, we measured the thicknesses of ASL patterns prepared by a lift-off method to investigate the effect of the ASL thicknesses on critical dimensions of the molds with ASLs and found that this effect is not negligible.

Particle-based Nano-Antennas at the Vis-NIR regime

DTIC Science & Technology

2013-11-01

PSS (poly(3,4-ethylenedioxythiophene) :poly(styrene sulfonate) is then spin coated and dried at 110oC to form a 50nm buffer layer partially covering...dominant effect is that during the spin coating of the 50nm PEDOT buffer a residual very thin layer coated also the top 50nm part of the Au disks...antennas, capacitive versus conductive coupling, on-demand design (termed ‘popcorn’ antennas), broadband plasmonic metamaterials, and light

Magic angle spinning NMR with metallized rotors as cylindrical microwave resonators.

PubMed

Scott, Faith J; Sesti, Erika L; Choi, Eric J; Laut, Alexander J; Sirigiri, Jagadishwar R; Barnes, Alexander B

2018-04-19

We introduce a novel design for millimeter wave electromagnetic structures within magic angle spinning (MAS) rotors. In this demonstration, a copper coating is vacuum deposited onto the outside surface of a sapphire rotor at a thickness of 50 nm. This thickness is sufficient to reflect 197-GHz microwaves, yet not too thick as to interfere with radiofrequency fields at 300 MHz or prevent sample spinning due to eddy currents. Electromagnetic simulations of an idealized rotor geometry show a microwave quality factor of 148. MAS experiments with sample rotation frequencies of ω r /2π = 5.4 kHz demonstrate that the drag force due to eddy currents within the copper does not prevent sample spinning. Spectra of sodium acetate show resolved 13 C J-couplings of 60 Hz and no appreciable broadening between coated and uncoated sapphire rotors, demonstrating that the copper coating does not prevent shimming and high-resolution nuclear magnetic resonance spectroscopy. Additionally, 13 C Rabi nutation curves of ω 1 /2π = 103 kHz for both coated and uncoated rotors indicate no detrimental impact of the copper coating on radio frequency coupling of the nuclear spins to the sample coil. We present this metal coated rotor as a first step towards an MAS resonator. MAS resonators are expected to have a significant impact on developments in electron decoupling, pulsed dynamic nuclear polarization (DNP), room temperature DNP, DNP with low-power microwave sources, and electron paramagnetic resonance detection. Copyright © 2018 John Wiley & Sons, Ltd.

Transition from Spin Dewetting to continuous film in spin coating of Liquid Crystal 5CB.

PubMed

Dhara, Palash; Bhandaru, Nandini; Das, Anuja; Mukherjee, Rabibrata

2018-05-08

Spin dewetting refers to spontaneous rupture of the dispensed solution layer during spin coating, resulting in isolated but periodic, regular sized domains of the solute and is pre-dominant when the solute concentration (C n ) is very low. In this article we report how the morphology of liquid crystal (LC) 5CB thin films coated on flat and patterned PMMA substrate transform from spin dewetted droplets to continuous films with increase in C n . We further show that within the spin dewetted regime, with gradual increase in the solute concentration, periodicity of the isotropic droplets (λ D ) as well as their mean diameter (d D ), gradually decreases, till the film becomes continuous at a critical concentration (C n *). Interestingly, the trend that λ D reduces with increase in C n is exact opposite to what is observed in thermal/solvent vapor induced dewetting of a thin film. The spin dewetted droplets exhibit transient Radial texture, in contrast to Schlieren texture observed in elongated threads and continuous films of 5CB, which remains in the Nematic phase at room temperature. Finally we show that by casting the film on a grating patterned substrate it becomes possible to align the spin dewetted droplets along the contours substrate patterns.

Optical characterization of antirelaxation coatings

NASA Astrophysics Data System (ADS)

Tsvetkov, S.; Gateva, S.; Cartaleva, S.; Mariotti, E.; Nasyrov, K.

2018-03-01

Antirelaxation coatings (ARC) are used in optical cells containing alkali metal vapor to reduce the depolarization of alkali atoms after collisions with the cell walls. The long-lived ground state polarization is a basis for development of atomic clocks, magnetometers, quantum memory, slow light experiments, precision measurements of fundamental symmetries etc. In this work, a simple method for measuring the number of collisions of the alkali atoms with the cell walls without atomic spin randomization (Nasyrov et al., Proc. SPIE (2015)) was applied to characterize the AR properties of two PDMS coatings prepared from different solutions in ether (PDMS 2% and PDMS 5%). We observed influence of the light-induced atomic desorption (LIAD) on the AR properties of coatings.

Correlation between the fine structure of spin-coated PEDOT:PSS and the photovoltaic performance of organic/crystalline-silicon heterojunction solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Funda, Shuji; Ohki, Tatsuya; Liu, Qiming

2016-07-21

We investigated the relationship between the fine structure of spin-coated conductive polymer poly(3,4-ethylenedioxythiphene):poly(styrene sulfonate) (PEDOT:PSS) films and the photovoltaic performance of PEDOT:PSS crystalline-Si (PEDOT:PSS/c-Si) heterojunction solar cells. Real-time spectroscopic ellipsometry revealed that there were two different time constants for the formation of the PEDOT:PSS network. Upon removal of the polar solvent, the PEDOT:PSS film became optically anisotropic, indicating a conformational change in the PEDOT and PSS chain. Polarized Fourier transform infrared attenuated total reflection absorption spectroscopy and Raman spectroscopy measurements also indicated that thermal annealing promoted an in-plane π-conjugated C{sub α} = C{sub β} configuration attributed to a thiophene ring in PEDOTmore » and an out-of-plane configuration of -SO{sub 3} groups in the PSS chain with increasing composition ratio of oxidized (benzoid) to neutral (quinoid) PEDOT, I{sub qui}/I{sub ben}. The highest power conversion efficiency for the spin-coated PEDOT:PSS/c-Si heterojunction solar cells was 13.3% for I{sub qui}/I{sub ben} = 9–10 without employing any light harvesting methods.« less

Apparently enhanced magnetization of Cu(I)-modified γ-Fe2O3 based nanoparticles

NASA Astrophysics Data System (ADS)

Qiu, Xiaoyan; He, Zhenghong; Mao, Hong; Zhang, Ting; Lin, Yueqiang; Liu, Xiaodong; Li, Decai; Meng, Xiangshen; Li, Jian

2017-11-01

Using a chemically induced transition method in FeCl2 solution, γ-Fe2O3 based magnetic nanoparticles, in which γ-Fe2O3 crystallites were coated with FeCl3ṡ6H2O, were prepared. During the synthesis of the γ-Fe2O3 nanoparticles Cu(I) modification of the particles was attempted. According to the results from both magnetization measurements and structural characterization, it was judged that a magnetic silent "dead layer", which can be attributed to spin disorder in the surface of the γ-Fe2O3 crystallites due to breaking of the crystal symmetry, existed in the unmodified particles. For the Cu(I)-modified sample, the CuCl thin layer on the γ-Fe2O3 crystallites incurred the crystal symmetry to reduce the spin disorder, which "awakened" the "dead layer" on the surface of the γ-Fe2O3 crystallites, enhancing the apparent magnetization of the Cu(I)-modified nanoparticles. It was determined that the surface spin disorder of the magnetic crystallite could be related to the coating layer on the crystallite, and can be modified by altering the coating layer to enhance the effective magnetization of the magnetic nanoparticles.

A low viscosity, low boiling point, clean solvent system for the rapid crystallisation of highly specular perovskite films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noel, Nakita K.; Habisreutinger, Severin N.; Wenger, Bernard

2017-01-01

Perovskite-based photovoltaics have, in recent years, become poised to revolutionise the solar industry. While there have been many approaches taken to the deposition of this material, one-step spin-coating remains the simplest and most widely used method in research laboratories. Although spin-coating is not recognised as the ideal manufacturing methodology, it represents a starting point from which more scalable deposition methods, such as slot-dye coating or ink-jet printing can be developed. Here, we introduce a new, low-boiling point, low viscosity solvent system that enables rapid, room temperature crystallisation of methylammonium lead triiodide perovskite films, without the use of strongly coordinating aproticmore » solvents. Through the use of this solvent, we produce dense, pinhole free films with uniform coverage, high specularity, and enhanced optoelectronic properties. We fabricate devices and achieve stabilised power conversion efficiencies of over 18% for films which have been annealed at 100 degrees C, and over 17% for films which have been dried under vacuum and have undergone no thermal processing. This deposition technique allows uniform coating on substrate areas of up to 125 cm2, showing tremendous promise for the fabrication of large area, high efficiency, solution processed devices, and represents a critical step towards industrial upscaling and large area printing of perovskite solar cells.« less

Effect of different coating layer on the topography and optical properties of ZnO nanostructured

NASA Astrophysics Data System (ADS)

Mohamed, R.; Mamat, M. H.; Malek, M. F.; Ismail, A. S.; Yusoff, M. M.; Asiah, M. N.; Khusaimi, Z.; Rusop, M.

2018-05-01

Magnesium (Mg) and aluminum (Al) co-doped zinc oxide (MAZO) thin films were synthesized on glass substrate by sol-gel spin coating method. MAZO thin films were prepared at different coating layers range from 1 to 9. Atomic Force Microscopy (AFM) was used to investigate the topography of the thin films. According to the AFM results, Root Means Square (RMS) of MAZO thin films was increased from 0.747 to 6.545 nm, with increase of number coating layer from 1 to 9, respectively. The results shown the variation on structural and topography properties of MAZO seed film when it's deposited at different coating layers on glass substrate. The optical properties was analyzed using UV-Vis spectroscopy. The obtained results show that the transmittance spectra was increased as thin films coating layer increases.

Using Organic Light-Emitting Electrochemical Thin-Film Devices to Teach Materials Science

ERIC Educational Resources Information Center

Sevian, Hannah; Muller, Sean; Rudmann, Hartmut; Rubner, Michael F.

2004-01-01

Materials science can be taught by applying organic light-emitting electrochemical thin-film devices and in this method students were allowed to make a light-emitting device by spin coating a thin film containing ruthenium (II) complex ions onto a glass slide. Through this laboratory method students are provided with the opportunity to learn about…

Comparative study of soft thermal printing and lamination of dry thick photoresist films for the uniform fabrication of polymer MOEMS on small-sized samples

NASA Astrophysics Data System (ADS)

Abada, S.; Salvi, L.; Courson, R.; Daran, E.; Reig, B.; Doucet, J. B.; Camps, T.; Bardinal, V.

2017-05-01

A method called ‘soft thermal printing’ (STP) was developed to ensure the optimal transfer of 50 µm-thick dry epoxy resist films (DF-1050) on small-sized samples. The aim was the uniform fabrication of high aspect ratio polymer-based MOEMS (micro-optical-electrical-mechanical system) on small and/or fragile samples, such as GaAs. The printing conditions were optimized, and the resulting thickness uniformity profiles were compared to those obtained via lamination and SU-8 standard spin-coating. Under the best conditions tested, STP and lamination produced similar results, with a maximum deviation to the central thickness of 3% along the sample surface, compared to greater than 40% for SU-8 spin-coating. Both methods were successfully applied to the collective fabrication of DF1050-based MOEMS designed for the dynamic focusing of VCSELs (vertical-cavity surface-emitting lasers). Similar, efficient electro-thermo-mechanical behaviour was obtained in both cases.

Long-Wavelength Infrared Sensing by Cytochrome C Protein Thin Film Deposited by the Spin Coating Method

PubMed Central

Lai, Bo-Yu; Chu, Chung-Hao; Su, Guo-Dung John

2013-01-01

High infrared absorption, large temperature coefficient of resistance (TCR) and small 1/f noise are preferred characteristics for sensing materials used in bolometers. In this paper, we discuss a cytochrome c protein as a potential sensing material for long-wavelength bolometers. We simulated and experimentally proved high infrared absorption of cytochrome c in the wavelength between 8 μm and 14 μm. Cytochrome c thin films were deposited on a hydrophilic surface using the spin coating method. The resistance variation with temperature is measured and we show that the TCR of cytochrome c thin films is consistently higher than 20%. The measured values of 1/f noise were as low as 2.33 × 10−13 V2/Hz at 60 Hz. Finally, we test the reliability of cytochrome c by measuring the resistance changes over time under varying conditions. We found that cytochrome c thin films deteriorated significantly without appropriate packaging. PMID:24264331

Formation of ordered microphase-separated pattern during spin coating of ABC triblock copolymer.

PubMed

Huang, Weihuan; Luo, Chunxia; Zhang, Jilin; Han, Yanchun

2007-03-14

In this paper, the authors have systematically studied the microphase separation and crystallization during spin coating of an ABC triblock copolymer, polystyrene-b-poly(2-vinylpyridine)-b-poly(ethylene oxide) (PS-b-P2VP-b-PEO). The microphase separation of PS-b-P2VP-b-PEO and the crystallization of PEO blocks can be modulated by the types of the solvent and the substrate, the spinning speed, and the copolymer concentration. Ordered microphase-separated pattern, where PEO and P2VP blocks adsorbed to the substrate and PS blocks protrusions formed hexagonal dots above the P2VP domains, can only be obtained when PS-b-P2VP-b-PEO is dissolved in N,N-dimethylformamide and the films are spin coated onto the polar substrate, silicon wafers or mica. The mechanism of the formation of regular pattern by microphase separation is found to be mainly related to the inducement of the substrate (middle block P2VP wetting the polar substrate), the quick vanishment of the solvent during the early stage of the spin coating, and the slow evaporation of the remaining solvent during the subsequent stage. On the other hand, the probability of the crystallization of PEO blocks during spin coating decreases with the reduced film thickness. When the film thickness reaches a certain value (3.0 nm), the extensive crystallization of PEO is effectively prohibited and ordered microphase-separated pattern over large areas can be routinely prepared. When the film thickness exceeds another definite value (12.0 nm), the crystallization of PEO dominates the surface morphology. For films with thickness between these two values, microphase separation and crystallization can simultaneously occur.

Characterization of nanocrystalline ZnO:Al films by sol-gel spin coating method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gareso, P. L., E-mail: pgareso@gmail.com; Rauf, N., E-mail: pgareso@gmail.com; Juarlin, E., E-mail: pgareso@gmail.com

2014-09-25

Nanocrystalline ZnO films doped with aluminium by sol-gel spin coating method have been investigated using optical transmittance UV-Vis and X-ray diffraction (X-RD) measurements. ZnO films were prepared using zinc acetate dehydrate (Zn(CH{sub 3}COO){sub 2}@@‡2H{sub 2}O), ethanol, and diethanolamine (DEA) as a starting material, solvent, and stabilizer, respectively. For doped films, AlCl{sub 3} was added to the mixture. The ZnO:Al films were deposited on a transparent conductive oxide (TCO) substrate using spin coating technique at room temperature with a rate of 3000 rpm in 30 sec. The deposited films were annealed at various temperatures from 400°C to 600°C during 60 minutes.more » The transmittance UV-Vis measurement results showed that after annealing at 400°C, the energy band gap profile of nanocrystalline ZnO:Al film was a blue shift. This indicated that the band gap of ZnO:Al increased after annealing due to the increase of crystalline size. As the annealing temperature increased the bandgap energy was a constant. In addition to this, there was a small oscillation occurring after annealing compared to the as–grown samples. In the case of X-RD measurements, the crystalinity of the films were amorphous before annealing, and after annealing the crystalinity became enhance. Also, X-RD results showed that structure of nanocrystalline ZnO:Al films were hexagonal polycrystalline with lattice parameters are a = 3.290 Å and c = 5.2531 Å.« less

Structural, compositional and optical properties of spin coated MoO3 thin film

NASA Astrophysics Data System (ADS)

Jain, Vishva; Shah, Dimple; Patel, K. D.; Zankat, Chetan

2018-05-01

The attraction towards the MoO3 thin film is due to its wide range of application base on its properties. Its application in the field of energy storage and conversion as a cathode material for rechargeable lithium ion battery, hole selective layer in solar cell and in pseudocapacitors makes it more attractive material. Taking in consideration, economical route and tailoring advantage of film formation we have used spin coating method for the synthesis of the film with Ammonium heptamolybdate (NH4)6Mo7O24 4H2O) and distilled water as the precursor and solvent respectively on the glass substrate. The method also provides the large area synthesis of the film which is beneficial for the commercial applications. The film was spin coated at 1600 rpm with 4 % weight per volume ratio. The film so formed was annealed at 300 °C for 3 hours. The structural investigation was done by the X-Ray diffraction technique which shows the thin film of polycrystalline type. The average crystallize size is about 50 nm. The composition of the film was studied with the help of EDAX. The optical properties were studied by the photoluminescence and UV Spectroscopy. The results from both the characterization are well matched with each other. Photoluminescence studies show band to band emission observed at 416 nm shown in the fig. 5. From UV spectroscopy, using transmission and absorption spectra we observed the band gap edge around 3 eV. This is in accordance with the photoluminescence result.

Ultra-low fouling and high antibody loading zwitterionic hydrogel coatings for sensing and detection in complex media.

PubMed

Chou, Ying-Nien; Sun, Fang; Hung, Hsiang-Chieh; Jain, Priyesh; Sinclair, Andrew; Zhang, Peng; Bai, Tao; Chang, Yung; Wen, Ten-Chin; Yu, Qiuming; Jiang, Shaoyi

2016-08-01

For surface-based diagnostic devices to achieve reliable biomarker detection in complex media such as blood, preventing nonspecific protein adsorption and incorporating high loading of biorecognition elements are paramount. In this work, a novel method to produce nonfouling zwitterionic hydrogel coatings was developed to achieve these goals. Poly(carboxybetaine acrylamide) (pCBAA) hydrogel thin films (CBHTFs) prepared with a carboxybetaine diacrylamide crosslinker (CBAAX) were coated on gold and silicon dioxide surfaces via a simple spin coating process. The thickness of CBHTFs could be precisely controlled between 15 and 150nm by varying the crosslinker concentration, and the films demonstrated excellent long-term stability. Protein adsorption from undiluted human blood serum onto the CBHTFs was measured with surface plasmon resonance (SPR). Hydrogel thin films greater than 20nm exhibited ultra-low fouling (<5ng/cm(2)). In addition, the CBHTFs were capable of high antibody functionalization for specific biomarker detection without compromising their nonfouling performance. This strategy provides a facile method to modify SPR biosensor chips with an advanced nonfouling material, and can be potentially expanded to a variety of implantable medical devices and diagnostic biosensors. In this work, we developed an approach to realize ultra-low fouling and high ligand loading with a highly-crosslinked, purely zwitterionic, carboxybetaine thin film hydrogel (CBHTF) coating platform. The CBHTF on a hydrophilic surface demonstrated long-term stability. By varying the crosslinker content in the spin-coated hydrogel solution, the thickness of CBHTFs could be precisely controlled. Optimized CBHTFs exhibited ultra-low nonspecific protein adsorption below 5ng/cm(2) measured by a surface plasmon resonance (SPR) sensor, and their 3D architecture allowed antibody loading to reach 693ng/cm(2). This strategy provides a facile method to modify SPR biosensor chips with an advanced nonfouling material, and can be potentially expanded to a variety of implantable medical devices and diagnostic biosensors. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Mesoporous Bioactive Glass Functionalized 3D Ti-6Al-4V Scaffolds with Improved Surface Bioactivity

PubMed Central

Ye, Xiaotong; Leeflang, Sander; Wu, Chengtie; Chang, Jiang; Zhou, Jie; Huan, Zhiguang

2017-01-01

Porous Ti-6Al-4V scaffolds fabricated by means of selective laser melting (SLM), having controllable geometrical features and preferable mechanical properties, have been developed as a class of biomaterials that hold promising potential for bone repair. However, the inherent bio-inertness of the Ti-6Al-4V alloy as the matrix of the scaffolds results in a lack in the ability to stimulate bone ingrowth and regeneration. The aim of the present study was to develop a bioactive coating on the struts of SLM Ti-6Al-4V scaffolds in order to add the desired surface osteogenesis ability. Mesoporous bioactive glasses (MBGs) coating was applied on the strut surfaces of the SLM Ti-6Al-4V scaffolds through spin coating, followed by a heat treatment. It was found that the coating could maintain the characteristic mesoporous structure and chemical composition of MBG, and establish good interfacial adhesion to the Ti-6Al-4V substrate. The compressive strength and pore interconnectivity of the scaffolds were not affected by the coating. Moreover, the results obtained from in vitro cell culture experiments demonstrated that the attachment, proliferation, and differentiation of human bone marrow stromal cells (hBMSCs) on the MBG-coated Ti-6Al-4V scaffolds were improved as compared with those on the conventional bioactive glass (BG)-coated Ti-6Al-4V scaffolds and bare-metal Ti-6Al-4V scaffolds. Our results demonstrated that the MBG coating by using the spinning coating method could be an effective approach to achieving enhanced surface biofunctionalization for SLM Ti-6Al-4V scaffolds. PMID:29077014

Lifetime Improvement of Organic Light Emitting Diodes using LiF Thin Film and UV Glue Encapsulation

NASA Astrophysics Data System (ADS)

Huang, Jian-Ji; Su, Yan-Kuin; Chang, Ming-Hua; Hsieh, Tsung-Eong; Huang, Bohr-Ran; Wang, Shun-Hsi; Chen, Wen-Ray; Tsai, Yu-Sheng; Hsieh, Huai-En; Liu, Mark O.; Juang, Fuh-Shyang

2008-07-01

This work demonstrates the use of lithium fluoride (LiF) as a passivation layer and a newly developed UV glue for encapsulation on the LiF passivation layer to enhance the stability of organic light-emitting devices (OLEDs). Devices with double protective layers showed a 25-fold increase in operational lifetime compared to those without any packaging layers. LiF has a low melting point and insulating characteristics and it can be adapted as both a protective layer and pre-encapsulation film. The newly developed UV glue has a fast curing time of only 6 s and can be directly spin-coated onto the surface of the LiF passivation layer. The LiF thin film plus spin-coated UV glue is a simple packaging method that reduces the fabrication costs of OLEDs.

Throughput increase by adjustment of the BARC drying time with coat track process

NASA Astrophysics Data System (ADS)

Brakensiek, Nickolas L.; Long, Ryan

2005-05-01

Throughput of a coater module within the coater track is related to the solvent evaporation rate from the material that is being coated. Evaporation rate is controlled by the spin dynamics of the wafer and airflow dynamics over the wafer. Balancing these effects is the key to achieving very uniform coatings across a flat unpatterned wafer. As today"s coat tracks are being pushed to higher throughputs to match the scanner, the coat module throughput must be increased as well. For chemical manufacturers the evaporation rate of the material depends on the solvent used. One measure of relative evaporation rates is to compare flash points of a solvent. The lower the flash point, the quicker the solvent will evaporate. It is possible to formulate products with these volatile solvents although at a price. Shipping and manufacturing a more flammable product increase chances of fire, thereby increasing insurance premiums. Also, the end user of these chemicals will have to take extra precautions in the fab and in storage of these more flammable chemicals. An alternative coat process is possible which would allow higher throughput in a distinct coat module without sacrificing safety. A tradeoff is required for this process, that being a more complicated coat process and a higher viscosity chemical. The coat process uses the fact that evaporation rate depends on the spin dynamics of the wafer by utilizing a series of spin speeds that first would set the thickness of the material followed by a high spin speed to remove the residual solvent. This new process can yield a throughput of over 150 wafers per hour (wph) given two coat modules. The thickness uniformity of less than 2 nm (3 sigma) is still excellent, while drying times are shorter than 10 seconds to achieve the 150 wph throughput targets.

Broadband moth-eye antireflection coatings on silicon

NASA Astrophysics Data System (ADS)

Sun, Chih-Hung; Jiang, Peng; Jiang, Bin

2008-02-01

We report a bioinspired templating technique for fabricating broadband antireflection coatings that mimic antireflective moth eyes. Wafer-scale, subwavelength-structured nipple arrays are directly patterned on silicon using spin-coated silica colloidal monolayers as etching masks. The templated gratings exhibit excellent broadband antireflection properties and the normal-incidence specular reflection matches with the theoretical prediction using a rigorous coupled-wave analysis (RCWA) model. We further demonstrate that two common simulation methods, RCWA and thin-film multilayer models, generate almost identical prediction for the templated nipple arrays. This simple bottom-up technique is compatible with standard microfabrication, promising for reducing the manufacturing cost of crystalline silicon solar cells.

Enhanced bulk heterojunction devices prepared by thermal and solvent vapor annealing processes

DOEpatents

Forrest, Stephen R.; Thompson, Mark E.; Wei, Guodan; Wang, Siyi

2017-09-19

A method of preparing a bulk heterojunction organic photovoltaic cell through combinations of thermal and solvent vapor annealing are described. Bulk heterojunction films may prepared by known methods such as spin coating, and then exposed to one or more vaporized solvents and thermally annealed in an effort to enhance the crystalline nature of the photoactive materials.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Badran, Hussain Ali, E-mail: badran_hussein@yahoo.com; Ajeel, Khalid I.; Lazim, Haidar Gazy

Highlights: • Active layer (P3HT:PCBM) has been deposited on substrate type by spin coating at 1000 rpm. • The device was completed by evaporating a 60 nm thick, circular gold electrodes onto the P3HT:PCBM. • Nonlinear refractive indices of the three particle sizes are found to be of the order of 10{sup −7} cm{sup 2}/W - Abstract: Organic solar cells are based on (3-hexylthiophene):[6,6]-phenyl C61-butyric acid with methyl ester Bulk Heterojunction. An inverted structure has been fabricated using nano-anatase crystalline titanium dioxide, as the electron transport layer, which was prepared on either the Indium Tin Oxide coated glass (ITO—glass), ormore » Silicon wafer, as well as on glass substrates by the sol–gel method, at different spin speed, using the spin-coating system. The effect of thickness on the surface morphology and on the optical properties of TiO{sub 2} layer, was investigated using the Atomic Force Microscopy (AFM), X-ray diffraction, and UV–visible spectrophotometer. The samples were examined to feature currents and voltages, in the darkness and light extraction efficiency of the solar cell. The highest open-circuit voltage, V{sub oc}, and power conversion efficiency were 0.66% and 0.39%, fabricated with 90 nm, respectively. The non-linear optical properties of nano-anatase TiO{sub 2} sol–gel, were investigated at different particle sizes, using the z-scan technique.« less

Fabrication of electrically bistable organic semiconducting/ferroelectric blend films by temperature controlled spin coating.

PubMed

Hu, Jinghang; Zhang, Jianchi; Fu, Zongyuan; Weng, Junhui; Chen, Weibo; Ding, Shijin; Jiang, Yulong; Zhu, Guodong

2015-03-25

Organic semiconducting/ferroelectric blend films attracted much attention due to their electrical bistability and rectification properties and thereof the potential in resistive memory devices. During film deposition from the blend solution, spinodal decomposition induced phase separation, resulting in discrete semiconducting phase whose electrical property could be modulated by the continuous ferroelectric phase. However, blend films processed by common spin coating method showed extremely rough surfaces, even comparable to the film thickness, which caused large electrical leakage and thus compromised the resistive switching performance. To improve film roughness and thus increase the productivity of these resistive devices, we developed temperature controlled spin coating technique to carefully adjust the phase separation process. Here we reported our experimental results from the blend films of ferroelectric poly(vinylidene fluoride-trifluoroethylene (P(VDF-TrFE)) and semiconducting poly(3-hexylthiophene) (P3HT). We conducted a series of experiments at various deposition temperatures ranging from 20 to 90 °C. The resulting films were characterized by AFM, SEM, and VPFM to determine their structure and roughness. Film roughness first decreased and then increased with the increase of deposition temperature. Electrical performance was also characterized and obviously improved insulating property was obtained from the films deposited between 50 and 70 °C. By temperature control during film deposition, it is convenient to efficiently fabricate ferroelectric/semiconducting blend films with good electrical bistability.

Multilayer bioactive glass/zirconium titanate thin films in bone tissue engineering and regenerative dentistry

PubMed Central

Mozafari, Masoud; Salahinejad, Erfan; Shabafrooz, Vahid; Yazdimamaghani, Mostafa; Vashaee, Daryoosh; Tayebi, Lobat

2013-01-01

Surface modification, particularly coatings deposition, is beneficial to tissue-engineering applications. In this work, bioactive glass/zirconium titanate composite thin films were prepared by a sol-gel spin-coating method. The surface features of the coatings were studied by scanning electron microscopy, atomic force microscopy, and spectroscopic reflection analyses. The results show that uniform and sound multilayer thin films were successfully prepared through the optimization of the process variables and the application of carboxymethyl cellulose as a dispersing agent. Also, it was found that the thickness and roughness of the multilayer coatings increase nonlinearly with increasing the number of the layers. This new class of nanocomposite coatings, comprising the bioactive and inert components, is expected not only to enhance bioactivity and biocompatibility, but also to protect the surface of metallic implants against wear and corrosion. PMID:23641155

In Situ GIWAXS Analysis of Solvent and Additive Effects on PTB7 Thin Film Microstructure Evolution during Spin Coating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manley, Eric F.; Strzalka, Joseph; Fauvell, Thomas J.

The influence of solvent and processing additives on the pathways and rates of crystalline morphology formation for spin-coated semiconducting PTB7 (poly[[4,8-bis[(2- ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)- carbonyl]-thieno[3,4-b]thiophenediyl

In Situ GIWAXS Analysis of Solvent and Additive Effects on PTB7 Thin Film Microstructure Evolution during Spin Coating

DOE PAGES

Manley, Eric F.; Strzalka, Joseph; Fauvell, Thomas J.; ...

2017-10-09

The influence of solvent and processing additives on the pathways and rates of crystalline morphology formation for spin-coated semiconducting PTB7 (poly[[4,8-bis[(2- ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)- carbonyl]-thieno[3,4-b]thiophenediyl

High-mobility ultrathin semiconducting films prepared by spin coating.

PubMed

Mitzi, David B; Kosbar, Laura L; Murray, Conal E; Copel, Matthew; Afzali, Ali

2004-03-18

The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (approximately 50 A), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS(2-x)Se(x) films, which exhibit n-type transport, large current densities (>10(5) A cm(-2)) and mobilities greater than 10 cm2 V(-1) s(-1)--an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

High-mobility ultrathin semiconducting films prepared by spin coating

NASA Astrophysics Data System (ADS)

Mitzi, David B.; Kosbar, Laura L.; Murray, Conal E.; Copel, Matthew; Afzali, Ali

2004-03-01

The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (~50Å), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS2-xSex films, which exhibit n-type transport, large current densities (>105Acm-2) and mobilities greater than 10cm2V-1s-1-an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

Effects of fluorine contamination on spin-on dielectric thickness in semiconductor manufacturing

NASA Astrophysics Data System (ADS)

Kim, Hyoung-ryeun; Hong, Soonsang; Kim, Samyoung; Oh, Changyeol; Hwang, Sung Min

2018-03-01

In the recent semiconductor industry, as the device shrinks, spin-on dielectric (SOD) has been adopted as a widely used material because of its excellent gap-fill, efficient throughput on mass production. SOD film must be uniformly thin, homogeneous and free of particle defects because it has been perfectly perserved after chemical-mechanical polishing (CMP) and etching process. Spin coating is one of the most common techniques for applying SOD thin films to substrates. In spin coating process, the film thickness and uniformity are strong function of the solution viscosity, the final spin speed and the surface properties. Especially, airborne molecular contaminants (AMCs), such as HF, HCl and NH3, are known to change to surface wetting characteristics. In this work, we study the SOD film thickness as a function of fluorine contamination on the wafer surface. To examine the effects of airborne molecular contamination, the wafers are directly exposed to HF fume followed by SOD coating. It appears that the film thickness decreases by higher contact angle on the wafer surface due to fluorine contamination. The thickness of the SOD film decreased with increasing fluorine contamination on the wafer surface. It means that the wafer surface with more hydrophobic property generates less hydrogen bonding with the functional group of Si-NH in polysilazane(PSZ)-SOD film. Therefore, the wetting properties of silicon wafer surfaces can be degraded by inorganic contamination in SOD coating process.

Evaluation of the optical characteristics of c-axis oriented zinc oxide thin films grown by sol gel spin coating technique

NASA Astrophysics Data System (ADS)

Baisakh, K.; Behera, S.; Pati, S.

2018-03-01

In this work we have systematically studied the optical characteristics of synthesized wurzite zinc oxide thin films exhibiting (002) orientation. Using sol gel spin coating technique zinc oxide thin films are grown on pre cleaned fused quartz substrates. Structural properties of the films are studied using X-ray diffraction analysis. Micro structural analysis and thickness of the grown samples are analyzed using field emission scanning electron microscopy. With an aim to investigate the optical characteristics of the grown zinc oxide thin films the transmission and reflection spectra are evaluated in the ultraviolet-visible (UV-VIS) range. Using envelope method, the refractive index, extinction coefficient, absorption coefficient, band gap energy and the thickness of the synthesized films are estimated from the recorded UV-VIS spectra. An attempt has also been made to study the influence of crystallographic orientation on the optical characteristics of the grown films.

Highly reliable spin-coated titanium dioxide dielectric

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mondal, Sandip, E-mail: sandipmondal@physics.iisc.ernet.in; Kumar, Arvind; Rao, K. S. R. Koteswara

Dielectric degradation as low as 0.3 % has been observed for a highly reliable Titanium dioxide (TiO{sub 2}) film after constant voltage stressing (CVS) with – 4 V for 10{sup 5} second at room temperature (300 K). The film was fabricated by sol –gel spin – coating method on a lightly doped p-Si (~10{sup 15} cm{sup −3}) substrate. The equivalent oxide thickness (EOT) is 7 nm with a dielectric constant 33 (at 1 MHz). Metal – Oxide – Semiconductor (MOS) capacitors have been fabricated with an optimum annealing temperature of 800°C for one hour in a preheated furnace. The dielectricmore » degradation is annealing temperature dependent. A degradation of 1.4 %, 1.2 % and 1.1 % has been observed for 400°C, 600°C and 1000°C temperature annealed MOS respectively. The dielectric degradation increases below or above the optimum temperature of annealing.« less

Highly transparent and flexible circuits through patterning silver nanowires into microfluidic channels.

PubMed

Sun, Jing; Zhou, Wenhui; Yang, Haibo; Zhen, Xue; Ma, Longfei; Williams, Dirk; Sun, Xudong; Lang, Ming-Fei

2018-05-10

The development of flexible and transparent devices requires completely transparent and flexible circuits (TFCs). To overcome the disadvantages of the previously reported TFCs that are partially transparent, lacking pattern control, or labor consuming, we achieve true TFCs via a facile process with precise pattern control, exhibiting concurrent high transparency, conductivity, flexibility, stretchability, and robustness. A highly transparent and flexible conductive film is first made through spin coating silver nanowires (AgNWs) onto polydimethylsiloxane (PDMS), and demonstrates simultaneous high transparency (90.86%) and low sheet resistance (3.22 Ω sq-1). Taking advantage of microfluidic technology, circuits with ultraprecise and complex patterns from the microscale to milliscale are obtained through spin coating of AgNWs into microfluidic channels on PDMS. Without elaborate processing, this method may be suitable for mass production, which would contribute enormously to potential applications in wearable medical equipment and transparent electronic devices.

Preparation of Sb2S3 nanocrystals modified TiO2 dendritic structure with nanotubes for hybrid solar cell

NASA Astrophysics Data System (ADS)

Li, Yingpin; Wei, Yanan; Feng, Kangning; Hao, Yanzhong; Pei, Juan; Sun, Bao

2018-06-01

Array of TiO2 dendritic structure with nanotubes was constructed on transparent conductive fluorine-doped tin oxide glass (FTO) with titanium potassium oxalate as titanium source. Sb2S3 nanocrystals were successfully deposited on the TiO2 substrate via spin-coating method. Furthermore, TiO2/Sb2S3/P3HT/PEDOT:PSS composite film was prepared by successively spin-coating P3HT and PEDOT:PSS on TiO2/Sb2S3. It was demonstrated that the modification of TiO2 dendritic structure with Sb2S3 could enhance the light absorption in the visible region. The champion hybrid solar cell assembled by TiO2/Sb2S3/P3HT/PEDOT:PSS composite film achieved a power conversion efficiency (PCE) of 1.56%.

Effect of size and moisture on the mechanical behavior of SU-8 thin films

NASA Astrophysics Data System (ADS)

Robin, C. J.; Jonnalagadda, K. N.

2016-02-01

The mechanical properties of SU-8 were investigated in conjunction with size effect, mechanical anisotropy and moisture absorption. Uniaxial tensile experiments were conducted on SU-8 films of 500 nm and 2 μm thickness. A spin coating process was used to fabricate the films with one set from a single coat (single layer) and the others containing multiple coats (multilayer) with pre-baking in between. The stress versus strain response was obtained from in situ optical experiments and a digital image correlation method. Compared to single layer films, the multilayer films showed a significant increase in mechanical properties as well as in-plane anisotropy. This anisotropy was confirmed using Fourier transform infrared spectroscopy and attributed to the spin coating process, which resulted in higher crosslinking density in the film, and molecular orientation in the radial direction. Moisture absorption studies revealed that the mechanical properties were affected by water, which exists in both the free and bonded form in the polymer and acts as a plasticizer. The effect of moisture was similar in both the single and multilayer films, but was higher for the latter due to multiple processing steps as well as the existence of higher percentage of epoxy polar groups.

Environmentally stable perovskite film for active material of high stability solid state solar cells

NASA Astrophysics Data System (ADS)

Bahtiar, A.; Putri, M.; Nurazizah, E. S.; Risdiana; Furukawa, Y.

2018-05-01

We studied new perovskite material lead (II) thiocyanate [Pb(SCN)2] in ambient air with humidity above 90%. We prepared perovskite film by use of two-step method combination of spin-coating and dip-coating technique. The Pb(SCN)2 film was first spin-coated either on bare glass or TiO2 coated glass and then followed by dipping it into methylammonium iodide (MAI) solution. The UV-Vis spectrum of Pb(SCN)2 film shows absorption at wavelength shorter than 400 nm. Meanwhile, perovskite MAPb(SCN)xI3-x film absorps light ranging from 300 nm to 760 nm, which shows that the perovskite film can absorp more light to be converted into free charge carrier for generating electricity in solar cells. The XRD patterns shows that perovskite peaks are clearly observed which confirms that perovskite is already well formed. We also observe no significant changes in XRD pattern of perovskite films after stored for five days at ambient air with humidity exceed 90%. This result shows that perovskite MAPb(SCN)XI3-X film is environmentally stable, therefore high stability perovskite solar cells is expected to be produced in ambient air with high humidity. This is in accordance with the SEM images of surface morphology that shows no “pin-hole”.

Method of manufacturing fibrous hemostatic bandages

DOEpatents

Larsen, Gustavo; Spretz, Ruben; Velarde-Ortiz, Raffet

2012-09-04

A method of manufacturing a sturdy and pliable fibrous hemostatic dressing by making fibers that maximally expose surface area per unit weight of active ingredients as a means for aiding in the clot forming process and as a means of minimizing waste of active ingredients. The method uses a rotating object to spin off a liquid biocompatible fiber precursor, which is added at its center. Fibers formed then deposit on a collector located at a distance from the rotating object creating a fiber layer on the collector. An electrical potential difference is maintained between the rotating disk and the collector. Then, a liquid procoagulation species is introduced at the center of the rotating disk such that it spins off the rotating disk and coats the fibers.

Polymer thin film as coating layer to prevent corrosion of metal/metal oxide film

NASA Astrophysics Data System (ADS)

Sarkar, Suman; Kundu, Sarathi

2018-04-01

Thin film of polymer is used as coating layer and the corrosion of metal/metal oxide layer is studied with the variation of the thickness of the coating layer. The thin layer of polystyrene is fabricated using spin coating method on copper oxide (CuO) film which is deposited on glass substrate using DC magnetron sputtering technique. Thickness of the polystyrene and the CuO layers are determined using X-ray reflectivity (XRR) technique. CuO thin films coated with the polystyrene layer are exposed to acetic acid (2.5 v/v% aqueous CH3COOH solution) environments and are subsequently analyzed using UV-Vis spectroscopy and atomic force microscopy (AFM). Surface morphology of the film before and after interaction with the acidic environment is determined using AFM. Results obtained from the XRR and UV-Vis spectroscopy confirm that the thin film of polystyrene acts as an anticorrosion coating layer and the strength of the coating depends upon the polymer layer thickness at a constant acid concentration.

Enhanced sensitivity of a microfabricated resonator using a graphene-polystyrene bilayer membrane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yun, Minhyuk; Lee, Eunho; Cho, Kilwon

2014-08-18

A graphene layer was synthesized using chemical vapor deposition methods and a polystyrene solution was spin-cast onto the graphene film. The graphene-polystyrene bilayer membrane was attached between the two tines of a microfabricated quartz tuning fork (QTF). The modulus of the graphene-polystyrene bilayer was measured to be twice that of a pristine polystyrene membrane. Exposure of the membrane-coated QTF to ethanol vapor decreased the resonance frequency of the microresonator. The bilayer membrane-coated QTF produced a frequency change that was three times the change obtained using a polystyrene membrane-coated QTF, with a lower degree of degradation in the Q factor. Themore » limit of detection of the bilayer membrane-coated QTF to ethanol vapor was determined to be 20 ppm.« less

First wall for polarized fusion reactors

DOEpatents

Greenside, H.S.; Budny, R.V.; Post, D.E. Jr.

1985-01-29

A first-wall or first-wall coating for use in a fusion reactor having polarized fuel may be formed of a low-Z non-metallic material having slow spin relaxation, i.e., a depolarization rate greater than 1 sec/sup -1/. Materials having these properties include hydrogenated and deuterated amorphous semiconductors. A method for preventing the rapid depolarization of a polarized plasma in a fusion device may comprise the step of providing a first-wall or first-wall coating formed of a low-Z, non-metallic material having a depolarization rate greater than 1 sec/sup -1/.

Optical Properties of Fe3O4 Thin Films Prepared from the Iron Sand by Spin Coating Method

NASA Astrophysics Data System (ADS)

Yulfriska, N.; Rianto, D.; Murti, F.; Darvina, Y.; Ramli, R.

2018-04-01

Research on magnetic oxide is growing very rapidly. This magnetic oxide can be found in nature that is in iron sand. One of the beaches in Sumatera Barat containing iron sand is Tiram Beach, Padang Pariaman District, Sumatera Barat. The content of iron sand is generally in the form of magnetic minerals such as magnetite, hematite, and maghemit. Magnetite has superior properties that can be developed into thin films. The purpose of this research is to investigate the optical properties of transmittance, absorbance, reflectance and energy gap from Fe3O4 thin films. This type of research is an experimental research. The iron sand obtained from nature is first purified using a permanent magnet, then made in nanoparticle size using HEM-E3D with milling time for 30 hours. After that, the process of making thin film with sol-gel spin coating method. In this research, variation of rotation speed from spin coating is 1000 rpm, 2000 rpm and 3000 rpm. Based on XRD results indicated that the iron sand of Tiram beach contains magnetite minerals and the SEM results show that the thickness of the thin films formed is 25μm, 24μm and 11μm. The characterization tool used for characterizing optical properties is the UV-VIS Spectrophotometer. So it can be concluded that the greater the speed of rotation the thickness of the thin layer will be smaller, resulting in the transmittance and reflectance will be greater, while the absorbance will be smaller. Energy gap obtained from this research is 3,75eV, 3,75eV and 3,74eV. So the average energy gap obtained is 3,75eV.

Process optimization for particle removal on blank chrome mask plates in preparation for resist application

NASA Astrophysics Data System (ADS)

Osborne, Stephen; Smith, Eryn; Woster, Eric; Pelayo, Anthony

2002-03-01

As integrated circuits require smaller lines to provide the memory and processing capability for tomorrow's marketplace, the photomask industry is adopting higher contrast resists to improve photomask lithography. Photomask yield for several high-contrast resist recipes may be improved by coating masks at the mask shop. When coating at a mask shop, an effective method is available that uses coat/bake cluster tools to ensure blanks are clean prior to coating. Many high-contrast resists are available, and some are more susceptible to time-dependent performance factors than conventional resists. One of these factors is the time between coating and writing. Although future methods may reduce the impact of this factor, one current trend is to reduce this time by coating plates at the mask shop just prior to writing. Establishing an effective process to clean blanks prior to coating is necessary for product quality control and is a new task that is critical for maskmakers who previously purchased mask plates but have decided to begin coating them within their facility. This paper provides a strategy and method to be used within coat/bake cluster tools to remove particle contamination from mask blanks. The process uses excimer-UV ionizing radiation and ozone to remove organic contaminants, and then uses a wet process combined with megasonic agitation, surfactant, and spin forces. Megasonic agitation with surfactant lifts up particles, while the convective outflow of water enhances centripetal shear without accumulating harmful charge.

Surface Enhancement For Optical Plastics

NASA Astrophysics Data System (ADS)

Masso, Jon D.

1988-07-01

Optical plastics can be molded or cast to replicate traditional spherical and aspheric lenses. It is possible to obtain good optical quality, but often it is necessary or desirable to enhance the surface characteristics in a variety of ways. These include improving the abrasion resistance, chemical resistance, the addition of anti-fog, or anti-static characteristics, applying electrically conductive coatings, and applying coatings or selective absorbers for light and color control. Coatings may be entirely organic or organo-silanes applied by dipping or spinning. All dielectric coatings such as quartz abrasion resistant coatings or multilayer dielectric coatings for reflection reduction or enhancement may be applied by vacuum vapor deposition. This paper discusses a number of these coatings and surface treatments. The paper describes their characteristics and includes discussions of their durability and environmental stability. The adhesion of coatings to plastic substrate depends on the specific substrate and coating materials. Pretreatments or primers are used to promote good coating adhesion. A coating used for one purpose will generally affect other properties of the plastic and trade-offs are sometimes required. A description is given of several test methods which have been found useful in evaluating the quality of the various coatings.

Controlled thickness and dielectric constant titanium-doped SiO2 thin films on silicon by sol gel process

NASA Astrophysics Data System (ADS)

Liu, H. L.; Wang, S. S.; Zhou, Yan; Lam, Yee Loy; Chan, Yuen Chuen; Kam, Chan Hin

1997-08-01

In this paper, we report the preparation of crack-free relatively thick SiO2-TiO2 thin films on silicon substrates using the sol-gel spin-coating method. The influence of the process parameters on the quality of the film, such as the solution condition, the spin-coating speed, the heat treatment temperature and time, have been studied. We found that the cracking of the film could be avoided by selecting the right sol composition ratios, adding PVA to the sold and properly controlling the heat treatment. Most importantly, we discovered that by polishing the edges of the film after the deposition of each single layer, the number of such layers that deposited without crack formation could be substantially increased. The refractive index profile and thickness of the film have been determined using prism coupling technique and the inverse WKB method. The refractive index was found to depend on the content of TiO2 as well as the heat treatment condition. Using an AFM, the surface morphology of the film was found to be good.

Ultra-high mobility transparent organic thin film transistors grown by an off-centre spin-coating method.

PubMed

Yuan, Yongbo; Giri, Gaurav; Ayzner, Alexander L; Zoombelt, Arjan P; Mannsfeld, Stefan C B; Chen, Jihua; Nordlund, Dennis; Toney, Michael F; Huang, Jinsong; Bao, Zhenan

2014-01-01

Organic semiconductors with higher carrier mobility and better transparency have been actively pursued for numerous applications, such as flat-panel display backplane and sensor arrays. The carrier mobility is an important figure of merit and is sensitively influenced by the crystallinity and the molecular arrangement in a crystal lattice. Here we describe the growth of a highly aligned meta-stable structure of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) from a blended solution of C8-BTBT and polystyrene by using a novel off-centre spin-coating method. Combined with a vertical phase separation of the blend, the highly aligned, meta-stable C8-BTBT films provide a significantly increased thin film transistor hole mobility up to 43 cm(2) Vs(-1) (25 cm(2) Vs(-1) on average), which is the highest value reported to date for all organic molecules. The resulting transistors show high transparency of >90% over the visible spectrum, indicating their potential for transparent, high-performance organic electronics.

Facile Fabrication of Multifunctional Aramid Nanofiber Films by Spin Coating

NASA Astrophysics Data System (ADS)

Lyu, Jing; Liu, Lehao; Zhao, Xing; Shang, Yudong; Zhao, Tingkai; Li, Tiehu

2016-11-01

Polymer matrices with excellent mechanical properties, thermal stability and other features are highly demanded for the effective utilization within nanocomposites. Here, we fabricate free-standing aramid nanofiber films via spin coating of an aramid nanofiber/dimethyl sulfoxide solution. Compared with traditional film fabrication methods, this process is time-saving and also able to easily tune the thickness of the films. The resultant films show greatly improved stretchability than that of Kevlar threads and relatively high mechanical strength. Typically, these films with a thickness of 5.5 µm show an ultimate strength of 182 MPa with an ultimate tensile strain of 10.5%. We also apply a finite element modeling to simulate the strain and strength distributions of the films under uniaxial tension, and the results of the simulation are in accordance with the experimental data. Furthermore, the aramid nanofiber films exhibit outstanding thermostability (decomposition at 550 °C under N2 atmosphere and 500 °C in air) and chemical inertness, which would endure acid and alkali. The simple method demonstrated here provides an important way to prepare high-performance aramid nanofiber films for designing new composite systems.

Doped indium nitride thin film by sol-gel spin coating method

NASA Astrophysics Data System (ADS)

Lee, Hui San; Ng, Sha Shiong; Yam, Fong Kwong

2017-12-01

In this study, magnesium doped indium nitride (InN:Mg) thin films grown on silicon (100) substrate were prepared via sol-gel spin coating method followed by nitridation process. A custom-made tube furnace was used to perform the nitridation process. Through this method, the low dissociation temperature issue of InN:Mg thin films can be solved. The deposited InN:Mg thin films were investigated using various techniques. The X-rays diffraction results revealed that two intense diffraction peaks correspond to wurtzite structure InN (100), and InN (101) were observed at 29° and 33.1° respectively. Field emission scanning electron microscopy images showed that the surface of the films exhibits densely packed grains. The elemental composition of the deposited thin films was analyzed using energy dispersive X-rays spectroscopy. The detected atomic percentages for In, N, and Mg were 43.22 %, 3.28 %, and 0.61 % respectively. The Raman spectra showed two Raman- and infrared-active modes of E2 (High) and A1 (LO) of the wurtzite InN. The band gap obtained from the Tauc plot showed around 1.74 eV. Lastly, the average surface roughness measured by AFM was around 0.133 µm.

In situ scanning tunneling microscope tip treatment device for spin polarization imaging

DOEpatents

Li, An-Ping [Oak Ridge, TN; Jianxing, Ma [Oak Ridge, TN; Shen, Jian [Knoxville, TN

2008-04-22

A tip treatment device for use in an ultrahigh vacuum in situ scanning tunneling microscope (STM). The device provides spin polarization functionality to new or existing variable temperature STM systems. The tip treatment device readily converts a conventional STM to a spin-polarized tip, and thereby converts a standard STM system into a spin-polarized STM system. The tip treatment device also has functions of tip cleaning and tip flashing a STM tip to high temperature (>2000.degree. C.) in an extremely localized fashion. Tip coating functions can also be carried out, providing the tip sharp end with monolayers of coating materials including magnetic films. The device is also fully compatible with ultrahigh vacuum sample transfer setups.

Ferroelectric properties of PZT/BFO multilayer thin films prepared using the sol-gel method.

PubMed

Jo, Seo-Hyeon; Lee, Sung-Gap; Lee, Young-Hie

2012-01-05

In this study, Pb(Zr0.52Ti0.48)O3/BiFeO3 [PZT/BFO] multilayer thin films were fabricated using the spin-coating method on a Pt(200 nm)/Ti(10 nm)/SiO2(100 nm)/p-Si(100) substrate alternately using BFO and PZT metal alkoxide solutions. The coating-and-heating procedure was repeated several times to form the multilayer thin films. All PZT/BFO multilayer thin films show a void-free, uniform grain structure without the presence of rosette structures. The relative dielectric constant and dielectric loss of the six-coated PZT/BFO [PZT/BFO-6] thin film were approximately 405 and 0.03%, respectively. As the number of coatings increased, the remanent polarization and coercive field increased. The values for the BFO-6 multilayer thin film were 41.3 C/cm2 and 15.1 MV/cm, respectively. The leakage current density of the BFO-6 multilayer thin film at 5 V was 2.52 × 10-7 A/cm2.

Hydrophobic ultrathin films formed by fluorofunctional cage silsesquioxanes

NASA Astrophysics Data System (ADS)

Wamke, Anna; Makowiecki, Jaroslaw; Dopierała, Katarzyna; Karasiewicz, Joanna; Prochaska, Krystyna

2018-06-01

The usefulness of fluorofunctional cage silsesquioxanes (POSS) as coating materials effectively changing the surface properties of model substrates was analyzed. Five fully condensed silsesquioxanes (containing two types of organic groups attached to the Si-O cage: octafluoropentyloxypropyl (OFP) and trimethoxysilylethyl (TMS) at different ratios, one monofunctional derivative with OFP groups only and one open cage POSS derivative with three OFP and seven isobutyl groups as organic substituents were investigated. All POSS derivatives were applied to enhance hydrophobicity of quartz or glass plates by deposition of thin LB film transferred from the water subphase. Then, by comparison of water contact angles (WCA) on modified surfaces the effect of silsesquioxane structure (i.e. the TMS and fluoroalkyl group contents as well as the structure of silicon-oxygen cage) on hydrophobic properties was determined. Moreover, the texture of LB films formed by POSS considered was analyzed using the AFM technique. It has been established that the hydrophobizing properties of silsesquioxanes are considerably influenced not only by the number of OFP groups, but also by the silsesquioxane structure. The most effective appeared to be the open cage OFP-POSS derivative which produced coatings with water contact angles (WCA) equal to about 100 deg. Additionally the POSS derivatives studied were also used for dip-coating and spin-coating surface modification. The study has shown that fluorofunctional POSS derivatives can be effective hydrophobizing agents. Additionally applying the LB technique for surface modification allows obtaining substrate of enhanced hydrophobicity by using vanishingly small amount of the modifying substance in comparison to the dip-coating and spin-coating method, which is especially important from the economic viewpoint.

Fabrication of broadband antireflection coating at terahertz frequency using a hot emboss method

NASA Astrophysics Data System (ADS)

Li, YunZhou; Cai, Bin; Zhu, YiMing

2014-11-01

We fabricated a terahertz anti-reflective structure on a polystylene by using a hot-embossing method. Polystylene was spin-coated onto a silicon substrate and then transformed by using a metallic mould comprising a bunch of Chinese acupuncture needles. The transformation layer yielded gradient refractive index profiles on the substrate which can reduce the surface reflection effectively. The samples were evaluated by a terahertz time-domain spectroscope. Compared with a bare silicon substrate, we observed an increase of ~30% in the transmittance. We also observed broader bandwidth properties compared with a single-layer antireflective structure. The process imposes no substrate limiting; i.e., it has great potential to be applied onto various THz devices.

Fabrication of high-transmission microporous membranes by proton beam writing-based molding technique

NASA Astrophysics Data System (ADS)

Wang, Liping; Meyer, Clemens; Guibert, Edouard; Homsy, Alexandra; Whitlow, Harry J.

2017-08-01

Porous membranes are widely used as filters in a broad range of micro and nanofluidic applications, e.g. organelle sorters, permeable cell growth substrates, and plasma filtration. Conventional silicon fabrication approaches are not suitable for microporous membranes due to the low mechanical stability of thin film substrates. Other techniques like ion track etching are limited to the production of randomly distributed and randomly orientated pores with non-uniform pore sizes. In this project, we developed a procedure for fabricating high-transmission microporous membranes by proton beam writing (PBW) with a combination of spin-casting and soft lithography. In this approach, focused 2 MeV protons were used to lithographically write patterns consisting of hexagonal arrays of high-density pillars of few μm size in a SU-8 layer coated on a silicon wafer. After development, the pillars were conformably coated with a thin film of poly-para-xylylene (Parylene)-C release agent and spin-coated with polydimethylsiloxane (PDMS). To facilitate demolding, a special technique based on the use of a laser-cut sealing tape ring was developed. This method facilitated the successful delamination of 20-μm thick PDMS membrane with high-density micropores from the mold without rupture or damage.

Development of a cell culture surface conversion technique using alginate thin film for evaluating effect upon cellular differentiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakashima, Y., E-mail: yuta-n@mech.kumamoto-u.ac.jp; Graduate School of Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611; Tsusu, K.

2014-06-15

Here, we sought to develop a cell culture surface conversion technique that would not damage living cells. An alginate thin film, formed on a glass plate by spin coating of sodium alginate solution and dipping into calcium chloride solution, was used to inhibit adhesion of cells. The film could be removed by ethylenediaminetetraacetate (EDTA) at any time during cell culture, permitting observation of cellular responses to conversion of the culture surface in real time. Additionally, we demonstrated the validity of the alginate thin film coating method and the performance of the film. The thickness of the alginate thin film wasmore » controlled by varying the rotation speed during spin coating. Moreover, the alginate thin film completely inhibited the adhesion of cultured cells to the culture surface, irrespective of the thickness of the film. When the alginate thin film was removed from the culture surface by EDTA, the cultured cells adhered to the culture surface, and their morphology changed. Finally, we achieved effective differentiation of C2C12 myoblasts into myotube cells by cell culture on the convertible culture surface, demonstrating the utility of our novel technique.« less

Graphene oxide as a p-dopant and an anti-reflection coating layer, in graphene/silicon solar cells

NASA Astrophysics Data System (ADS)

Yavuz, S.; Kuru, C.; Choi, D.; Kargar, A.; Jin, S.; Bandaru, P. R.

2016-03-01

It is shown that coating graphene-silicon (Gr/Si) Schottky junction based solar cells with graphene oxide (GO) improves the power conversion efficiency (PCE) of the cells, while demonstrating unprecedented device stability. The PCE has been shown to be increased to 10.6% (at incident radiation of 100 mW cm-2) for the Gr/Si solar cell with an optimal GO coating thickness compared to 3.6% for a bare/uncoated Gr/Si solar cell. The p-doping of graphene by the GO, which also serves as an antireflection coating (ARC) has been shown to be a main contributing factor to the enhanced PCE. A simple spin coating process has been used to apply GO with thickness commensurate with an anti-refection coating (ARC) and indicates the suitability of the developed methodology for large-scale solar cell assembly.It is shown that coating graphene-silicon (Gr/Si) Schottky junction based solar cells with graphene oxide (GO) improves the power conversion efficiency (PCE) of the cells, while demonstrating unprecedented device stability. The PCE has been shown to be increased to 10.6% (at incident radiation of 100 mW cm-2) for the Gr/Si solar cell with an optimal GO coating thickness compared to 3.6% for a bare/uncoated Gr/Si solar cell. The p-doping of graphene by the GO, which also serves as an antireflection coating (ARC) has been shown to be a main contributing factor to the enhanced PCE. A simple spin coating process has been used to apply GO with thickness commensurate with an anti-refection coating (ARC) and indicates the suitability of the developed methodology for large-scale solar cell assembly. Electronic supplementary information (ESI) available: (i) Experimental methods, (ii) optical images of devices with and without graphene oxide (GO), (iii) comparison of the power conversion efficiency (PCE) due to the GO coating and nitric acid doping, (iv) specular and diffuse reflectance measurements, (v) stability data of pristine graphene/silicon (Gr/Si) solar cells. See DOI: 10.1039/c5nr09143h

Colored and semitransparent silver nanoparticle layers deposited by spin coating of silver nanoink

NASA Astrophysics Data System (ADS)

Yoon, Hoi Jin; Jo, Yejin; Jeong, Sunho; Lim, Jung Wook; Lee, Seung-Yun

2018-05-01

In this letter, we report on the fabrication and characterization of colored and semitransparent silver nanoparticle layers. A spin coating of silver nanoink is used to deposit silver nanoparticle layers onto substrates. The transmittance and color of the silver nanoparticle layers are significantly dependent on the spin speed and nanoink concentration, owing to variations in the size and distribution of the nanoparticles. Both color variation and efficiency improvement are achieved with the application of silver nanoparticles to semitransparent Si thin-film solar cells, which is associated with the excitation of the dipole or quadruple plasmon modes of the silver nanoparticles.

Hydroxyapatite, fluor-hydroxyapatite and fluorapatite produced via the sol-gel method: bonding to titanium and scanning electron microscopy.

PubMed

Tredwin, Christopher J; Georgiou, George; Kim, Hae-Won; Knowles, Jonathan C

2013-05-01

Hydroxyapatite (HA), fluor-hydroxyapatite (FHA) with varying levels of fluoride ion substitution and fluorapatite (FA) production has been characterised and optimised by the sol-gel method and the dissolution and biological properties of these materials were investigated. It was the objective of this study to investigate the potential bond strength and interaction of these materials with titanium. HA, FHA and FA were synthesised by a sol-gel method. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol-water based solution. Different amounts of ammonium fluoride (NH4F) were incorporated for the preparation of the FHA and FA sol-gels. Using a spin coating technique the sol-gels were coated onto commercially pure titanium disks and crystallised at various temperatures. Using scanning electron microscopy (SEM) and elemental analysis, the surface characteristics, coating thickness and interaction of the Ti substrate and coating were investigated. The bond strengths of the coating to the Ti were investigated using an Instron Universal Load Testing Machine. Statistical analysis was performed with a two-way analysis of variance and post hoc testing with a Bonferroni correction. (1) Coating speed inversely influenced the coating thickness. (2) Increasing fluoride ion substitution and heating temperature significantly increased bond strength and (3) increasing fluoride ion substitution increased the coating thickness. FHA and FA synthesised using the sol-gel technique may offer a superior alternative to coating titanium implants with HA and plasma spraying. HA, FHA and FA materials synthesised by the sol-gel method may also have a use as bone grafting materials. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Reliability and efficacy of organic passivation for polycrystalline silicon solar cells at room temperature

NASA Astrophysics Data System (ADS)

Shinde, Onkar S.; Funde, Adinath M.; Jadkar, Sandesh R.; Dusane, Rajiv O.; Dhere, Neelkanth G.; Ghaisas, Subhash V.

2016-09-01

Oleylamine is used as a passivating layer instead of commercial high temperature SiNx. Oleylamine coating applied on the n-type emitter side with p-type base polycrystalline silicon solar cells at room temperature using a simple spin coating method. It has been observed that there is 16% increase in efficiency after Oleylamine coating. Further, the solar cell was subjected to standard characterization namely current-voltage measurement for electrical parameters and Fourier transform infrared spectroscopy to understand the interaction of emitter surface and passivating Oleylamine. However, the passivation layer is not stable due to the reaction between Oleylamine and ambient air content such as humidity and carbon dioxide. This degradation can be prevented with suitable overcoating.

Tunable electro-optic filter stack

DOEpatents

Fontecchio, Adam K.; Shriyan, Sameet K.; Bellingham, Alyssa

2017-09-05

A holographic polymer dispersed liquid crystal (HPDLC) tunable filter exhibits switching times of no more than 20 microseconds. The HPDLC tunable filter can be utilized in a variety of applications. An HPDLC tunable filter stack can be utilized in a hyperspectral imaging system capable of spectrally multiplexing hyperspectral imaging data acquired while the hyperspectral imaging system is airborne. HPDLC tunable filter stacks can be utilized in high speed switchable optical shielding systems, for example as a coating for a visor or an aircraft canopy. These HPDLC tunable filter stacks can be fabricated using a spin coating apparatus and associated fabrication methods.

Structural properties of iron and nickel mixed oxide nano particles.

NASA Astrophysics Data System (ADS)

Dehipawala, Sunil; Samarasekara, Pubudu; Gafney, Harry

Small scale magnets have very high technological importance today. Instead of traditional expensive methods, scientists are exploring new low cost methods to produce micro magnets. We synthesized thin film magnets containing iron and nickel oxides. Films will be synthesized using sol-gel method and spin coating technique. Several different precursor concentrations were tested to find out the ideal concentrations for stable thin films. Structural properties of iron and nickel oxide particles were investigated using X-ray absorption and Mossbauer spectroscopy. PSC-CUNY.

Optically enhanced SnO{sub 2}/CdSe core/shell nanostructures grown by sol-gel spin coating method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Vijay, E-mail: vijaynadda83@gmail.com; Goswami, Y. C.; Rajaram, P.

2015-08-28

Synthesis of SnO{sub 2}/CdSe metal oxide/ chalcogenide nanostructures on glass micro slides using ultrasonic sol-gel process followed by spin coating has been reported. Stannous chloride, cadmium chloride and selenium dioxide compounds were used for Sn, Cd and Se precursors respectively. Ethylene glycol was used as complexing agent. The samples were characterized by XRD, SEM, AFM and UV-spectrophotometer. All the peaks shown in diffractograms are identified for SnO{sub 2}. Peak broadening observed in core shell due to stress behavior of CdSe lattice. Scanning electron microscope and AFM exhibits the conversion of cluster in to nanorods structures forms. Atomic force microscope showsmore » the structures in nanorods form and a roughness reduced 1.5194 nm by the deposition of CdSe. Uv Visible spectra shows a new absorption edge in the visible region make them useful for optoelectronic applications.« less

Patterning technology for solution-processed organic crystal field-effect transistors

PubMed Central

Li, Yun; Sun, Huabin; Shi, Yi; Tsukagoshi, Kazuhito

2014-01-01

Organic field-effect transistors (OFETs) are fundamental building blocks for various state-of-the-art electronic devices. Solution-processed organic crystals are appreciable materials for these applications because they facilitate large-scale, low-cost fabrication of devices with high performance. Patterning organic crystal transistors into well-defined geometric features is necessary to develop these crystals into practical semiconductors. This review provides an update on recentdevelopment in patterning technology for solution-processed organic crystals and their applications in field-effect transistors. Typical demonstrations are discussed and examined. In particular, our latest research progress on the spin-coating technique from mixture solutions is presented as a promising method to efficiently produce large organic semiconducting crystals on various substrates for high-performance OFETs. This solution-based process also has other excellent advantages, such as phase separation for self-assembled interfaces via one-step spin-coating, self-flattening of rough interfaces, and in situ purification that eliminates the impurity influences. Furthermore, recommendations for future perspectives are presented, and key issues for further development are discussed. PMID:27877656

Anisotropic growth and formation mechanism investigation of 1D ZnO nanorods in spin-coating sol-gel process.

PubMed

Song, Yijian; Zheng, Maojun; Ma, Li; Shen, Wenzhong

2010-01-01

ZnO nanorods are fabricated on glass substrate by spin-coating sol-gel process using non-basic aged solution and annealing. Sample solutions reserved in room temperature for different time (one day, one month, two months and four months) are prepared for the experiment. The morphology study indicates that the aging time has direct influence on the final products. This is verified by the Transmission Electron Microscopy and Photon Correlation Spectroscopy study. Small crystalline nanoparticles would gradually nucleate and aggregate in the sol during the aging process. They act as nucleation site for the secondary crystal growth into nanorods during anneal. Both the size of crystalline particles in the sol and the size of nanorods will grow bigger as the aging time increases. The products' structure and optical property are further studied by X-ray diffraction spectroscopy, Photoluminescence and Raman spectroscopy. This work also helps to further clarify the formation mechanism of ZnO nanorods by solution-based method.

Optical and electrical properties of sol-gel spin coated titanium dioxide thin films

NASA Astrophysics Data System (ADS)

Sahoo, Anusuya; Jayakrishnan, A. R.; Kamakshi, K.; Silva, J. P. B.; Sekhar, K. C.; Gomes, M. J. M.

2017-08-01

In this work; TiO2 thin films were deposited on glass and stainless steel substrates by sol-gel spin coating method. The films deposited on glass were annealed at different temperatures (Ta) in the range of 200 to 500 0C and that are deposited on steel substrate were annealed at 800 0C. The optical properties of TiO2 thin films were studied by using UV-VIS spectroscopy and photoluminescence (PL) spectroscopy. The transmittance on the average was found to ≥ 80 % and is found to sensitive to Ta. The PL spectra exhibited the strong emission band associated with band- to- band transition around 390 nm and the two weak bands at 480 and 510 nm associated to the oxygen defects and surface defects respectively. The current-voltage (I-V) characteristics of the Al/TiO2/steel capacitors were studied and analysed with application of various current mechanisms. Analysis reveals that the conduction in Al/TiO2/steel capacitors is governed by Poole-Frenkel mechanism.

Low-cost growth of magnesium doped gallium nitride thin films by sol-gel spin coating method

NASA Astrophysics Data System (ADS)

Amin, N. Mohd; Ng, S. S.

2018-01-01

Low-cost sol-gel spin coating growth of magnesium (Mg) doped gallium nitride (GaN) thin films with different concentrations of Mg was reported. The effects of the Mg concentration on the structural, surface morphology, elemental compositions, lattice vibrational, and electrical properties of the deposited films were investigated. X-ray diffraction results show that the Mg-doped samples have wurtzite structure with preferred orientation of GaN(002). The crystallite size decreases and the surface of the films with pits/pores were formed, while the crystalline quality of the films degraded as the Mg concentration increases from 2% to 6. %. All the Raman active phonon modes of the wurtzite GaN were observed while a broad peak attributed to the Mg-related lattice vibrational mode was detected at 669 cm-1. Hall effect results show that the resistivity of the thin films decreases while the hole concentration and hall mobility of thin films increases as the concentration of the Mg increases.

Solution-processed zinc oxide field-effect transistors based on self-assembly of colloidal nanorods.

PubMed

Sun, Baoquan; Sirringhaus, Henning

2005-12-01

Colloidal zinc oxide (ZnO) nanocrystals are attractive candidates for a low-temperature and solution-processible semiconductor for high-performance thin-film field-effect transistors (TFTs). Here we show that by controlling the shape of the nanocrystals from spheres to rods the semiconducting properties of spin-coated ZnO films can be much improved as a result of increasing particle size and self-alignment of the nanorods along the substrate. Postdeposition hydrothermal growth in an aqueous zinc ion solution has been found to further enhance grain size and connectivity and improve device performance. TFT devices made from 65-nm-long and 10-nm-wide nanorods deposited by spin coating have been fabricated at moderate temperatures of 230 degrees C with mobilities of 0.61 cm(2)V(-1)s(-1) and on/off ratios of 3 x 10(5) after postdeposition growth, which is comparable to the characteristics of TFTs fabricated by traditional sputtering methods.

Structural Investigation of Cesium Lead Halide Perovskites for High-Efficiency Quantum Dot Light-Emitting Diodes.

PubMed

Le, Quyet Van; Kim, Jong Beom; Kim, Soo Young; Lee, Byeongdu; Lee, Dong Ryeol

2017-09-07

We have investigated the effect of reaction temperature of hot-injection method on the structural properties of CsPbX 3 (X: Br, I, Cl) perovskite nanocrystals (NCs) using small- and wide-angle X-ray scattering. It is confirmed that the size of the NCs decreased as the reaction temperature decreased, resulting in stronger quantum confinement. The cubic-phase perovskite NCs formed despite the fact that the reaction temperatures increased from 140 to 180 °C; however, monodispersive NC cubes that are required for densely packing self-assembly film were formed only at lower temperatures. From the X-ray scattering measurements, the spin-coated film from more monodispersive perovskite nanocubes synthesized at lower temperatures resulted in more preferred orientation. This dense-packing perovskite film with preferred orientation yielded efficient light-emitting diode (LED) performance. Thus the dense-packing structure of NC assemblies formed after spin-coating should be considered for high-efficient LEDs based on perovskite quantum dots in addition to quantum confinement effect of the quantum dots.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Le, Quyet Van; Kim, Jong Beom; Kim, Soo Young

We have investigated the effect of reaction temperature of hot-injection method on the structural properties of CsPbX3 (X: Br, I, Cl) perovskite nanocrystals (NCs) using the small- and wide-angle X-ray scattering. It is confirmed that the size of the NCs decreased as the reaction temperature decreased, resulting stronger quantum confinement. The cubic-phase perovskite NCs were formed despite the reaction temperatures increased from 140 to 180 °C. However, monodispersive NC cubes which are required for densely packing self-assembly film were only formed at lower temperatures. From the X-ray scattering measurements, the spin-coated film from more monodispersive perovskite nanocubes synthesized at lowermore » temperatures resulted in more preferred orientation. This dense-packing perovskite film with preferred orientation yielded efficient light-emitting diode (LED) performance. Thus, the dense-packing structure of NC assemblies formed after spin-coating should be considered for high-efficient LEDs based on perovskite quantum dots in addition to quantum confinement effect of the quantum dots.« less

Effect of the co-spun anode functional layer on the performance of the direct-methane microtubular solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Meng, Xiuxia; Gong, Xun; Yin, Yimei; Yang, Naitao; Tan, Xiaoyao; Ma, Zi-Feng

2014-02-01

NiO-YSZ/porous YSZ (NiO-YSZ/p-YSZ) dual-layer hollow fibers have been fabricated by a co-spinning-sintering method, on which a dense YSZ films has been formed by a dip-coating and sintering process. A LSM-YSZ ink has been dip-coated on the dense YSZ films as cathode, while the Cu-CeO2 carbon-resistant catalyst has been impregnated in the p-YSZ layer to form double-anode supported micro tubular fuel cells (MT-SOFCs). The thickness of the Ni-YSZ layer, so called anode functional layer (AFL), is controlled from 74 μm to 13 μm by varying the spinning rates of the NiO-YSZ dopes. The maximum power density of an MT-SOFC, which is fabricated based on a thin co-spun AFL, reaches 566 mW cm-2 operated at 850 °C fed with dry methane, and is stably operated for 85 h without power declination.

Colloidal CuInSe2 nanocrystals thin films of low surface roughness

NASA Astrophysics Data System (ADS)

de Kergommeaux, Antoine; Fiore, Angela; Faure-Vincent, Jérôme; Pron, Adam; Reiss, Peter

2013-03-01

Thin-film processing of colloidal semiconductor nanocrystals (NCs) is a prerequisite for their use in (opto-)electronic devices. The commonly used spin-coating is highly materials consuming as the overwhelming amount of deposited matter is ejected from the substrate during the spinning process. Also, the well-known dip-coating and drop-casting procedures present disadvantages in terms of the surface roughness and control of the film thickness. We show that the doctor blade technique is an efficient method for preparing nanocrystal films of controlled thickness and low surface roughness. In particular, by optimizing the deposition conditions, smooth and pinhole-free films of 11 nm CuInSe2 NCs have been obtained exhibiting a surface roughness of 13 nm root mean square (rms) for a 350 nm thick film, and less than 4 nm rms for a 75 nm thick film. Invited talk at the 6th International Workshop on Advanced Materials Science and Nanotechnology, 30 October-2 November 2012, Ha Long, Vietnam.

Enhancement of the Ultraviolet Photoresponsivity of Al-doped ZnO Thin Films Prepared by using the Sol-gel Spin-coating Method

NASA Astrophysics Data System (ADS)

Lee, Wookbin; Leem, Jae-Young

2018-03-01

We report the structural, morphological, optical, and ultraviolet (UV) photoresponse properties of Al-doped ZnO (AZO) thin films prepared on silicon substrates with different Al doping concentrations by using the sol-gel spin-coating method. An analysis of the X-ray diffraction patterns of the AZO thin films revealed that the average grain size decreased and the c-axis lattice constant increased with Al content. The field-emission scanning electron microscopy images showed that with Al doping, the grain size decreased, but the film density increased with increasing Al doping concentration from 0% to 3%. These results indicate that the surface area of the film increased with increasing Al doping. The absorbance spectra revealed that the UV absorbance of the AZO thin films increased with increasing Al doping concentration and that the absorption onset shifted towards lower energies. The photoluminescence spectra revealed that with increasing Al doping, the intensity of the visible emission greatly decreased and the visible emission peak shifted forward lower energy (a red shift). The UV sensor based on the AZO thin films exhibited a higher responsivity than that based on the undoped ZnO thin film. Therefore, this study provides a facile method for improving the photoresponsivity of UV sensors.

Continuous blade coating for multi-layer large-area organic light-emitting diode and solar cell

NASA Astrophysics Data System (ADS)

Chen, Chun-Yu; Chang, Hao-Wen; Chang, Yu-Fan; Chang, Bo-Jie; Lin, Yuan-Sheng; Jian, Pei-Siou; Yeh, Han-Cheng; Chien, Hung-Ta; Chen, En-Chen; Chao, Yu-Chiang; Meng, Hsin-Fei; Zan, Hsiao-Wen; Lin, Hao-Wu; Horng, Sheng-Fu; Cheng, Yen-Ju; Yen, Feng-Wen; Lin, I.-Feng; Yang, Hsiu-Yuan; Huang, Kuo-Jui; Tseng, Mei-Rurng

2011-11-01

A continuous roll-to-roll compatible blade-coating method for multi-layers of general organic semiconductors is developed. Dissolution of the underlying film during coating is prevented by simultaneously applying heating from the bottom and gentle hot wind from the top. The solvent is immediately expelled and reflow inhibited. This method succeeds for polymers and small molecules. Uniformity is within 10% for 5 cm by 5 cm area with a mean value of tens of nanometers for both organic light-emitting diode (OLED) and solar cell structure with little material waste. For phosphorescent OLED 25 cd/A is achieved for green, 15 cd/A for orange, and 8 cd/A for blue. For fluorescent OLED 4.3 cd/A is achieved for blue, 9 cd/A for orange, and 6.9 cd/A for white. For OLED with 2 cm by 3 cm active area, the luminance variation is within 10%. Power conversion efficiency of 4.1% is achieved for polymer solar cell, similar to spin coating using the same materials. Very-low-cost and high-throughput fabrication of efficient organic devices is realized by the continuous blade-only method.

Enhancement on crystallinity property of low annealed PbTiO3 thin films for metal-insulator-metal capacitor

NASA Astrophysics Data System (ADS)

Nurbaya, Z.; Wahid, M. H.; Rozana, M. D.; Alrokayan, S. A. H.; Khan, H. A.; Rusop, M.

2018-05-01

This study presents the investigation on crystallinity property of PbTiO3 thin films towards metal-insulator-metal capacitor device fabrication. The preparation of the thin films utilizes sol-gel spin coating method with low annealing temperature effect. Hence, structural and electrical characterization is brought to justify the thin films consistency.

High-κ TiO{sub 2} thin film prepared by sol-gel spin-coating method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Arvind; Mondal, Sandip; Rao, K. S. R. Koteswara, E-mail: ksrkrao@physics.iisc.ernet.in

2015-06-24

High-k TiO{sub 2} thin film on p-type silicon substrate was fabricated by a combined sol-gel and spin coating method. Thus deposited titania film had anatase phase with a small grain size of 16 nm and surface roughness of ≅ 0.6 nm. The oxide capacitance (C{sub ox}), flat band capacitance (C{sub FB}), flat band voltage (V{sub FB}), oxide trapped charge (Q{sub ot}), calculated from the high frequency (1 MHz) C-V curve were 0.47 nF, 0.16 nF, − 0.91 V, 4.7x10{sup −12} C, respectively. As compared to the previous reports, a high dielectric constant of 94 at 1 MHz frequency was observedmore » in the devices investigated here and an equivalent oxide thickness (EOT) was 4.1 nm. Dispersion in accumulation capacitance shows a linear relationship with AC frequencies. Leakage current density was found in acceptable limits (2.1e-5 A/cm{sup 2} for −1 V and 5.7e-7 A/cm{sup 2} for +1 V) for CMOS applications.« less

Synthesis and Characterization of TiO2/SiO2 Thin Film via Sol-Gel Method

NASA Astrophysics Data System (ADS)

Halin, D. S. C.; Abdullah, M. M. A. B.; Mahmed, N.; Malek, S. N. A. Abdul; Vizureanu, P.; Azhari, A. W.

2017-06-01

TiO2/SiO2 thin films were prepared by sol-gel spin coating method. Structural, surface morphology and optical properties were investigated for different annealing temperatures at 300°C, 400°C and 500°C. X-ray diffraction pattern show that brookite TiO2 crystalline phase with SiO2 phase presence at 300°C. At higher temperatures of 400-500°C, the only phase presence was brookite. The surface morphology of film was characterized by scanning electron microscopy (SEM). The films annealed at 300°C shows an agglomeration of small flaky with crack free. When the temperature of annealing increase to 400-500°C, the films with large flaky and large cracks film were formed which was due to surface tension between the film and the air during the drying process. The UV-Vis spectroscopy shows that the film exhibits a low transmittance around 30% which was due to the substrate is inhomogeneously covered by the films. In order to improve the coverage of the film on the substrate, it has to repeatable the spin coating to ensure the substrate is fully covered by the films.

Immobilization-stabilization of proteins on nanofibrillated cellulose derivatives and their bioactive film formation.

PubMed

Arola, Suvi; Tammelin, Tekla; Setälä, Harri; Tullila, Antti; Linder, Markus B

2012-03-12

In a number of different applications for enzymes and specific binding proteins a key technology is the immobilization of these proteins to different types of supports. In this work we describe a concept for protein immobilization that is based on nanofibrillated cellulose (NFC). NFC is a form of cellulose where fibers have been disintegrated into fibrils that are only a few nanometers in diameter and have a very large aspect ratio. Proteins were conjugated through three different strategies using amine, epoxy, and carboxylic acid functionalized NFC. The conjugation chemistries were chosen according to the reactive groups on the NFC derivatives; epoxy amination, heterobifunctional modification of amino groups, and EDC/s-NHS activation of carboxylic acid groups. The conjugation reactions were performed in solution and immobilization was performed by spin coating the protein-NCF conjugates. The structure of NFC was shown to be advantageous for both protein performance and stability. The use of NFC allows all covalent chemistry to be performed in solution, while the immobilization is achieved by a simple spin coating or spreading of the protein-NFC conjugates on a support. This allows more scalable methods and better control of conditions compared to the traditional methods that depend on surface reactions.

Electrochemical impedance analysis of perovskite–electrolyte interfaces

DOE PAGES

Li, Zhen; Mercado, Candy C.; Yang, Mengjin; ...

2017-01-31

Here, the flat band potentials and carrier densities of spin coated and sprayed MAPbI 3, FA 0.85Cs 0.15PbI 3, and MAPbBr 3 perovskite films were determined using the Mott-Schottky relation. The films developed a space charge layer and exhibited p-type conduction with carrier concentration ~ 10 16 cm -3 for spin coated films. Electrochemical impedance spectra showed typical space charge impedance at frequencies > 1 kHz with increasing capacitance < 1 kHz owing to an ion diffusion component.

Cavity enhanced atomic magnetometry

PubMed Central

Crepaz, Herbert; Ley, Li Yuan; Dumke, Rainer

2015-01-01

Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations. PMID:26481853

Ferroelectric properties of PZT/BFO multilayer thin films prepared using the sol-gel method

PubMed Central

2012-01-01

In this study, Pb(Zr0.52Ti0.48)O3/BiFeO3 [PZT/BFO] multilayer thin films were fabricated using the spin-coating method on a Pt(200 nm)/Ti(10 nm)/SiO2(100 nm)/p-Si(100) substrate alternately using BFO and PZT metal alkoxide solutions. The coating-and-heating procedure was repeated several times to form the multilayer thin films. All PZT/BFO multilayer thin films show a void-free, uniform grain structure without the presence of rosette structures. The relative dielectric constant and dielectric loss of the six-coated PZT/BFO [PZT/BFO-6] thin film were approximately 405 and 0.03%, respectively. As the number of coatings increased, the remanent polarization and coercive field increased. The values for the BFO-6 multilayer thin film were 41.3 C/cm2 and 15.1 MV/cm, respectively. The leakage current density of the BFO-6 multilayer thin film at 5 V was 2.52 × 10-7 A/cm2. PMID:22221519

Nanostructured antistatic and antireflective thin films made of indium tin oxide and silica over-coat layer

NASA Astrophysics Data System (ADS)

Cho, Young-Sang; Hong, Jeong-Jin; Yang, Seung-Man; Choi, Chul-Jin

2010-08-01

Stable dispersion of colloidal indium tin oxide nanoparticles was prepared by using indium tin oxide nanopowder, organic solvent, and suitable dispersants through attrition process. Various comminution parameters during the attrition step were studied to optimize the process for the stable dispersion of indium tin oxide sol. The transparent and conductive films were fabricated on glass substrate using the indium tin oxide sol by spin coating process. To obtain antireflective function, partially hydrolyzed alkyl silicate was deposited as over-coat layer on the pre-fabricated indium tin oxide film by spin coating technique. This double-layered structure of the nanostructured film was characterized by measuring the surface resistance and reflectance spectrum in the visible wavelength region. The final film structure was enough to satisfy the TCO regulations for EMI shielding purposes.

Sol-gel NiFe2O4 nanoparticles: Effect of the silica coating

NASA Astrophysics Data System (ADS)

Larumbe, S.; Pérez-Landazábal, J. I.; Pastor, J. M.; Gómez-Polo, C.

2012-05-01

NiFe2O4 and NiFe2O4-SiO2 nanoparticles were synthesized by a sol-gel method using citric acid as fuel, giving rise its combustion to the crystallization of the spinel phase. Different synthesis conditions were analyzed with the aim of obtaining stoichiometric NiFe2O4 nanoparticles. The spinel structure in the calcined nanoparticles (400 °C, 2 h) was evaluated by x-ray diffraction. Their nanometer size (mean diameters around 10-15 nm) was confirmed through electron microscopy (field emission scanning electron microscopy and transmission electron microscopy). Rietveld refinement indicates the existence of a small percentage of NiO and Fe3O4 phases and a certain degree of structural disorder. The main effect of the silica coating is to enhance the disorder effects and prevent the crystalline growth after post-annealing treatments. Due to the small particle size, the nanoparticles display characteristic superparamagnetic behaviour and surface effects associated to a spin-glass like state: i.e., reduction in the saturation magnetization values and splitting of the zero field cooled (ZFC)-field cooled (FC) high field magnetization curves. The fitting of the field dependence of the ZFC-FC irreversibility temperatures to the Almeida—Thouless equation confirms the spin-glass nature of the detected magnetic phenomena. Exchange bias effects (shifts in the FC hysteresis loops) detected below the estimated freezing temperature support the spin-glass nature of the spin disorder effects.

Photoelectrochemical performance of NiO-coated ZnO-CdS core-shell photoanode

NASA Astrophysics Data System (ADS)

Iyengar, Pranit; Das, Chandan; Balasubramaniam, K. R.

2017-03-01

A nano-structured core-shell ZnO-CdS photoanode device with a mesoporous NiO co-catalyst layer was fabricated using solution-processing methods. The growth of the sparse ZnO nano-rod film with a thickness of ca. 930 nm was achieved by optimizing parameters such as the thickness of the ZnO seed layer, choice of Zn precursor salt and the salt concentration. CdS was then coated by a combination of spin coating and spin SILAR (Successive Ionic Layer Adsorption and Reaction) methods to completely fill the interspace of ZnO nano-rods. The uniform CdS surface facilitated the growth of a continuous mesoporous NiO layer. Upon illumination of 100 mW·cm-2 AM 1.5 G radiation the device exhibits stable photocurrents of 2.15 mA·cm-2 at 1.23 V and 0.92 mA·cm-2 at 0.00 V versus RHE, which are significantly higher as compared to the bare ZnO-CdS device. The excellent performance of the device can be ascribed to the higher visible region absorption by CdS, and effective separation of the photogenerated charge carriers due to the suitable band alignment and nanostructuring. Additionally, the mesoporous NiO overlayer offered a larger contact area with the electrolyte and promoted the kinetics enabling higher and stable photocurrent even till the 35th min. of testing.

The opportunity and challenge of spin coat based nanoimprint lithography

NASA Astrophysics Data System (ADS)

Jung, Wooyung; Cho, Jungbin; Choi, Eunhyuk; Lim, Yonghyun; Bok, Cheolkyu; Tsuji, Masatoshi; Kobayashi, Kei; Kono, Takuya; Nakasugi, Tetsuro

2017-03-01

Since multi patterning with spacer was introduced in NAND flash memory1, multi patterning with spacer has been a promising solution to overcome the resolution limit. However, the increase in process cost of multi patterning with spacer must be a serious burden to device manufacturers as half pitch of patterns gets smaller.2, 3 Even though Nano Imprint Lithography (NIL) has been considered as one of strong candidates to avoid cost issue of multi patterning with spacer, there are still negative viewpoints; template damage induced from particles between template and wafer, overlay degradation induced from shear force between template and wafer, and throughput loss induced from dispensing and spreading resist droplet. Jet and Flash Imprint Lithography (J-FIL4, 5, 6) has contributed to throughput improvement, but still has these above problems. J-FIL consists of 5 steps; dispense of resist droplets on wafer, imprinting template on wafer, filling the gap between template and wafer with resist, UV curing, and separation of template from wafer. If dispensing resist droplets by inkjet is replaced with coating resist at spin coater, additional progress in NIL can be achieved. Template damage from particle can be suppressed by thick resist which is spin-coated at spin coater and covers most of particles on wafer, shear force between template and wafer can be minimized with thick resist, and finally additional throughput enhancement can be achieved by skipping dispense of resist droplets on wafer. On the other hand, spin-coat-based NIL has side effect such as pattern collapse which comes from high separation energy of resist. It is expected that pattern collapse can be improved by the development of resist with low separation energy.

Micropatterning of poly(dimethylsiloxane) using a photoresist lift-off technique for selective electrical insulation of microelectrode arrays

PubMed Central

Park, Jaewon; Kim, Hyun Soo; Han, Arum

2009-01-01

A poly(dimethylsiloxane) (PDMS) patterning method based on a photoresist lift-off technique to make an electrical insulation layer with selective openings is presented. The method enables creating PDMS patterns with small features and various thicknesses without any limitation in the designs and without the need for complicated processes or expensive equipments. Patterned PDMS layers were created by spin-coating liquid phase PDMS on top of a substrate having sacrificial photoresist patterns, followed by a photoresist lift-off process. The thickness of the patterned PDMS layers could be accurately controlled (6.5–24 µm) by adjusting processing parameters such as PDMS spin-coating speeds, PDMS dilution ratios, and sacrificial photoresist thicknesses. PDMS features as small as 15 µm were successfully patterned and the effects of each processing parameter on the final patterns were investigated. Electrical resistance tests between adjacent electrodes with and without the insulation layer showed that the patterned PDMS layer functions properly as an electrical insulation layer. Biocompatibility of the patterned PDMS layer was confirmed by culturing primary neuron cells on top of the layer for up to two weeks. An extensive neuronal network was successfully formed, showing that this PDMS patterning method can be applied to various biosensing microdevices. The utility of this fabrication method was further demonstrated by successfully creating a patterned electrical insulation layer on flexible substrates containing multi-electrode arrays. PMID:19946385

Direct Observation on Spin-Coating Process of PS- b -P2VP Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogawa, Hiroki; Takenaka, Mikihito; Miyazaki, Tsukasa

We studied the structural development of symmetric poly(styrene-b-2-vinylpyridine) (PS-b-P2VP) block copolymers during spin-coating using in situ grazing incidence small angle X-ray scattering (GISAXS) measurements. During the spin-coating process, after the formation of the micelles in dilute solution, the selective solvent induced two kinds of the morphological transition. Firstly, the disordered spherical micelles were transformed into a BCC lattice of spheres of which the (110) plane was oriented perpendicularly to the substrate surface. Secondly, further evaporation induced a transition from spheres on the BCC lattice into cylindrical structures. The orientation of the cylinders perpendicular to the substrate surface was induced bymore » solvent convection perpendicular to the substrate, which occurs during rapid solvent evaporation. After this transition, vitrification of PS and P2VP prevented any further transition from cylinders to the more thermodynamically stable lamellar structures, as are generally observed as the bulk equilibrium state.« less

Polymer blend lithography: A versatile method to fabricate nanopatterned self-assembled monolayers.

PubMed

Huang, Cheng; Moosmann, Markus; Jin, Jiehong; Heiler, Tobias; Walheim, Stefan; Schimmel, Thomas

2012-01-01

A rapid and cost-effective lithographic method, polymer blend lithography (PBL), is reported to produce patterned self-assembled monolayers (SAM) on solid substrates featuring two or three different chemical functionalities. For the pattern generation we use the phase separation of two immiscible polymers in a blend solution during a spin-coating process. By controlling the spin-coating parameters and conditions, including the ambient atmosphere (humidity), the molar mass of the polystyrene (PS) and poly(methyl methacrylate) (PMMA), and the mass ratio between the two polymers in the blend solution, the formation of a purely lateral morphology (PS islands standing on the substrate while isolated in the PMMA matrix) can be reproducibly induced. Either of the formed phases (PS or PMMA) can be selectively dissolved afterwards, and the remaining phase can be used as a lift-off mask for the formation of a nanopatterned functional silane monolayer. This "monolayer copy" of the polymer phase morphology has a topographic contrast of about 1.3 nm. A demonstration of tuning of the PS island diameter is given by changing the molar mass of PS. Moreover, polymer blend lithography can provide the possibility of fabricating a surface with three different chemical components: This is demonstrated by inducing breath figures (evaporated condensed entity) at higher humidity during the spin-coating process. Here we demonstrate the formation of a lateral pattern consisting of regions covered with 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS) and (3-aminopropyl)triethoxysilane (APTES), and at the same time featuring regions of bare SiO(x). The patterning process could be applied even on meter-sized substrates with various functional SAM molecules, making this process suitable for the rapid preparation of quasi two-dimensional nanopatterned functional substrates, e.g., for the template-controlled growth of ZnO nanostructures [1].

Simple and fast polydimethylsiloxane (PDMS) patterning using a cutting plotter and vinyl adhesives to achieve etching results.

PubMed

Hyun Kim; Sun-Young Yoo; Ji Sung Kim; Zihuan Wang; Woon Hee Lee; Kyo-In Koo; Jong-Mo Seo; Dong-Il Cho

2017-07-01

Inhibition of polydimethylsiloxane (PDMS) polymerization could be observed when spin-coated over vinyl substrates. The degree of polymerization, partially curing or fully curing, depended on the PDMS thickness coated over the vinyl substrate. This characteristic was exploited to achieve simple and fast PDMS patterning method using a vinyl adhesive layer patterned through a cutting plotter. The proposed patterning method showed results resembling PDMS etching. Therefore, patterning PDMS over PDMS, glass, silicon, and gold substrates were tested to compare the results with conventional etching methods. Vinyl stencils with widths ranging from 200μm to 1500μm were used for the procedure. To evaluate the accuracy of the cutting plotter, stencil designed on the AutoCAD software and the actual stencil widths were compared. Furthermore, this method's accuracy was also evaluated by comparing the widths of the actual stencils and etched PDMS results.

Tribological properties of self-assembled monolayers of catecholic imidazolium and the spin-coated films of ionic liquids.

PubMed

Liu, Jianxi; Li, Jinlong; Yu, Bo; Ma, Baodong; Zhu, Yangwen; Song, Xinwang; Cao, Xulong; Yang, Wu; Zhou, Feng

2011-09-20

A novel compound of an imidazolium type of ionic liquid (IL) containing a biomimetic catecholic functional group normally seen in mussel adhesive proteins was synthesized. The IL can be immobilized on a silicon surface and a variety of other engineering material surfaces via the catecholic anchor, allowing the tribological protection of these substrates for engineering applications. The surface wetting and adhesive properties and the tribological property of the synthesized self-assembled monolayers (SAMs) are successfully modulated by altering the counteranions. The chemical composition and wettability of the IL SAMs were characterized by means of X-ray photoelectron spectroscopy (XPS) and contact angle (CA) measurements. The adhesive and friction forces were measured with an atomic force microscope (AFM) on the nanometer scale. IL composite films were prepared by spin coating thin IL films on top of the SAMs. The macrotribological properties of these IL composite films were investigated with a pin-on-disk tribometer. The results indicate that the presence of IL SAMs on a surface can improve the wettability of spin-coated ionic liquids and thus the film quality and the tribological properties. These films registered a reduced friction coefficient and a significantly enhanced durability and load-carrying capacity. The tribological properties of the composite films are better than those of pure IL films because the presence of the monolayers improves the adhesion and compatibility of spin-coated IL films with substrates. © 2011 American Chemical Society

Size dependent nonlinear optical properties of spin coated zinc oxide-polystyrene nanocomposite films

NASA Astrophysics Data System (ADS)

Jeeju, Pullarkat P.; Jayalekshmi, S.; Chandrasekharan, K.; Sudheesh, P.

2012-11-01

Using simple wet chemical method at room temperature, zinc oxide (ZnO) nanoparticles embedded in polystyrene (PS) matrix were synthesized. The size of the ZnO nanoparticles could be varied by varying the precursor concentration, reaction time and stirring speed. Transparent films of ZnO/PS nanocomposites of thickness around 1 μm were coated on ultrasonically cleaned glass substrates by spin coating. The optical absorptive nonlinearity in ZnO/PS nanocomposite films was investigated using open aperture Z-scan technique with nanosecond laser pulses at 532 nm. The results indicate optical limiting type nonlinearity in the films due to two-photon absorption in ZnO. These films also show a self-defocusing type negative nonlinear refraction in closed aperture Z-scan experiment. The observed nonlinear absorption is strongly dependent on particle size and the normalized transmittance could be reduced to as low as 0.43 by the suitable choice of the ZnO nanoparticle size. These composite films can hence be used as efficient optical limiters for sensor protection. The much-pronounced nonlinear response of these composite films, compared to pure ZnO, combined with the improved stability of ZnO nanoparticles in the PS matrix offer prospects of application of these composite films in the fabrication of stable non-linear optical devices.

Highly dispersible diamond nanoparticles for pretreatment of diamond films on Si substrate

NASA Astrophysics Data System (ADS)

Zhao, Shenjie; Huang, Jian; Zhou, Xinyu; Ren, Bing; Tang, Ke; Xi, Yifan; Wang, Lin; Wang, Linjun; Lu, Yicheng

2018-03-01

High quality diamond film on Si substrate was synthesized by coating diamond nanoparticles prepared by polyglycerol grafting (ND-PG) dispersion as pre-treatment method. Transmission electron microscope indicates that ND-PG is much more dispersible than untreated nanoparticles in organic solvents. The surface morphology was characterized by scanning electron microscope while atomic force microscope was conducted to measure the surface roughness. Microstructure properties were carried out by Raman spectroscopy and X-ray diffraction. The results revealed an increase in nucleation density, an acceleration of growth rate and an improvement of film crystalline quality by using spin-coating ND-PG pretreatment.

Modified Surface Having Low Adhesion Properties to Mitigate Insect Residue Adhesion

NASA Technical Reports Server (NTRS)

Wohl, Christopher J., Jr. (Inventor); Smith, Joseph G., Jr. (Inventor); Siochi, Emilie J. (Inventor); Penner, Ronald K. (Inventor)

2016-01-01

A process to modify a surface to provide reduced adhesion surface properties to mitigate insect residue adhesion. The surface may include the surface of an article including an aircraft, an automobile, a marine vessel, all-terrain vehicle, wind turbine, helmet, etc. The process includes topographically and chemically modifying the surface by applying a coating comprising a particulate matter, or by applying a coating and also topographically modifying the surface by various methods, including but not limited to, lithographic patterning, laser ablation and chemical etching, physical vapor phase deposition, chemical vapor phase deposition, crystal growth, electrochemical deposition, spin casting, and film casting.

Formation of nanodiamond films from aqueous suspensions during spin coating

NASA Astrophysics Data System (ADS)

Lebedev-Stepanov, P. V.; Molchanov, S. P.; Vasil'ev, A. L.; Mitrokhin, V. P.; Yurasik, G. A.; Aleksenskii, A. E.; Dideikin, A. T.

2016-03-01

The formation of multifunctional ordered arrays of detonation diamond particles is studied during self-assembling in spin coating of films of evaporating microdroplets. It is shown that the most homogeneous layer of diamond particles on a crystalline silicon substrate forms at a rate of substrate rotation of 8000 min-1, whereas a relation between the distribution of particles and the radius is clearly detected at rates of about 2000 min-1. As the rate of substrate rotation increases from 2500 to 8000 min-1, the density of the coating of a silicon substrate with diamond nanoparticles decreases approximately threefold. A model is proposed to estimate the increase in the number of individual diamond "points" with the substrate rotation frequency.

Electrochemical detection of nitrite on poly(pyronin Y)/graphene nanocomposites modified ITO substrate

NASA Astrophysics Data System (ADS)

Şinoforoğlu, Mehmet; Dağcı, Kader; Alanyalıoğlu, Murat; Meral, Kadem

2016-06-01

The present study reports on an easy preparation of poly(pyronin Y)/graphene (poly(PyY)/graphene) nanocomposites thin films on indium tin oxide coated glass substrates (ITO). The thin films of poly(PyY)/graphene nanocomposites are prepared by a novel method consisting of three steps; (i) preparation of graphene oxide (GO) thin films on ITO by spin-coating method, (ii) self-assembly of PyY molecules from aqueous solution onto the GO thin film, (iii) surface-confined electropolymerization (SCEP) of the adsorbed PyY molecules on the GO thin film. The as-prepared poly(PyY)/graphene nanocomposites thin films are characterized by using electroanalytical and spectroscopic techniques. Afterwards, the graphene-based polymeric dye thin film on ITO is used as an electrode in an electrochemical cell. Its performance is tested for electrochemical detection of nitrite. Under optimized conditions, the electrocatalytical effect of the nanocomposites thin film through electrochemical oxidation of nitrite is better than that of GO coated ITO.

Polycrystalline BiFeO{sub 3} thin film synthesized via sol-gel assisted spin coating technique for photosensitive application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogle, K. A., E-mail: kashinath.bogle@gmail.com; Narwade, R. D.; Mahabole, M. P.

2016-05-06

We are reporting photosensitivity property of BiFeO{sub 3} thin film under optical illumination. The thin film used for photosensitivity work was fabricated via sol-gel assisted spin coating technique. I-V measurements on the Cu/BiFeO{sub 3}/Al structure under dark condition show a good rectifying property and show dramatic blue shit in threshold voltage under optical illumination. The microstructure, morphology and elemental analysis of the films were characterized by using XRD, UV-Vis, FTIR, SEM and EDS.

Scanning tunneling microscopy measurements of the spin Hall effect in tungsten films by using iron-coated tungsten tips

NASA Astrophysics Data System (ADS)

Xie, Ting; Dreyer, Michael; Bowen, David; Hinkel, Dan; Butera, R. E.; Krafft, Charles; Mayergoyz, Isaak

2018-05-01

Scanning tunneling microscopy experiments using iron-coated tungsten tips and current-carrying tungsten films have been conducted. An asymmetry of the tunneling current with respect to the change of the direction of the bias current through a tungsten film has been observed. It is argued that this asymmetry is a manifestation of the spin Hall effect in the current-carrying tungsten film. Nanoscale variations of this asymmetry across the tungsten film have been studied by using the scanning tunneling microscopy technique.

Improvements To Micro Contact Performance And Reliability

DTIC Science & Technology

2016-12-22

BAKE : □ 1 min 110°C hot plate bake OPTIONAL - For Grayscale Lithography: 1818 COAT: □ Flood wafer with 1818 □ 4 sec spread at 500 rpm...30 sec spin at 4,000 rpm, ramp=200 □ 75 sec 110°C hot plate bake GRAYSCALE PATTERNING: □ Follow grayscale patterning process for patterns...8217 □ 2 min 200°C hot plate bake 1818 COAT: □ Flood wafer with 1818 □ 4 sec spread at 500 rpm □ 30 sec spin at 4,000 rpm, ramp=200 □ 75 sec 110

New compact neutron supermirror transmission polarizer

NASA Astrophysics Data System (ADS)

Syromyatnikov, V. G.; Pusenkov, V. M.

2017-06-01

A new compact neutron supermirror transmission polarizer is suggested. The polarizer consists of a set of plates transparent to neutrons placed in the magnet gap. There are no air gaps between the plates. Polarizing supermirror coating without absorbing underlayer is deposited on the polished surfaces of the plates. Magnetic and nonmagnetic layers of the supermirror coating as well as the material of the plates have nearly equal neutron-optical potentials for spin-down neutrons. There is a considerable difference between neutron-optical potentials of layers in the supermirror structure for spin-up neutrons. As a result, spin-up neutrons reflect from the supermirror coating and deviate from their initial trajectories whereas spin-down neutrons do not practically reflect from the coating and, consequently, do not deviate from their initial trajectories. Thus, spin-down neutrons dominate near the axis of distribution of intensity on the angle for the beam transmitted through this polarizer, i.e., the beam is substantially polarized. Application is discussed of this polarizer in a research facility for small angle scattering of monochromatic neutrons with wavelengths λ = 4.5÷20 Å. The polarizing cross section of the beam of this facility is 30×30 mm2. Calculated parameters are presented of a polarizer on silicon plates with supermirror CoFe/TiZr (m = 2) coating. The suggested polarizer is compared with solid state bender, S-bender and widely known transmission neutron polarizer V- cavity in the same spectral range. Two polarizers are used to cover the wavelength range λ = 4.5 ÷20 Å: the first one whose length is 50 мм covers the range λ = 4.5 ÷10 Å and the second one whose length is 21.2 мм covers the range λ = 10 ÷20 Å. The length of each of these polarizers is more than 30 times smaller than that of V-cavity! On the other hand, basic parameters of the proposed polarizer, polarization of the beam falling on the sample P and transmission coefficient T- of the main spin component, exceed those of V-cavity. T- = 0.8 - 0.9 for both polarizers and for each wavelength range. Polarization P is very high. P is better than -0.99 for wavelength range λ = 12.5 ÷ 20 Å at the beam divergence of 24 mrad.

Protective Coating For Laser Drilling Of Silicon

NASA Technical Reports Server (NTRS)

Shlichta, Paul J.

1988-01-01

Sodium silicate prevents spattered silicon from fusing with surrounding material. Sodium silicate solution applied to wafer by dipping and draining or by spinning; application by spraying also works. When dried in oven, solution leaves thin coating of sodium silicate glass.

Study of flowability effect on self-planarization performance at SOC materials

NASA Astrophysics Data System (ADS)

Yun, Huichan; Kim, Jinhyung; Park, Youjung; Kim, Yoona; Jeong, Seulgi; Baek, Jaeyeol; Yoon, Byeri; Lim, Sanghak

2017-03-01

For multilayer process, importance of carbon-based spin-on hardmask material that replaces amorphous carbon layer (ACL) is ever increasing. Carbon-based spin-on hardmask is an organic polymer with high carbon content formulated in organic solvents for spin-coating application that is cured through baking. In comparison to CVD process for ACL, carbon-based spin-on hardmask material can offer several benefits: lower cost of ownership (CoO) and improved process time, as well as better gap-fill and planarization performances. Thus carbon-based spin-on hardmask material of high etch resistance, good gap-fill properties and global planarization performances over various pattern topographies are desired to achieve the fine patterning and high aspect ratio (A/R). In particular, good level of global planarization of spin coated layer over the underlying pattern topographies is important for self-aligned double patterning (SADP) process as it dictates the photolithographic margin. Herein, we report a copolymer carbon-based spin-on hardmask resin formulation that exhibits favorable film shrinkage profile and good etch resistance properties. By combining the favorable characteristics of each resin - one resin with good shrinkage property and the other with excellent etch resistance into the copolymer, it was possible to achieve a carbonbased spin-on hardmask formulation with desirable level of etch resistance and the planarization performances across various underlying substrate pattern topographies.

Photoresist thin-film effects on alignment process capability

NASA Astrophysics Data System (ADS)

Flores, Gary E.; Flack, Warren W.

1993-08-01

Two photoresists were selected for alignment characterization based on their dissimilar coating properties and observed differences on alignment capability. The materials are Dynachem OFPR-800 and Shipley System 8. Both photoresists were examined on two challenging alignment levels in a submicron CMOS process, a nitride level and a planarized second level metal. An Ultratech Stepper model 1500 which features a darkfield alignment system with a broadband green light for alignment signal detection was used for this project. Initially, statistically designed linear screening experiments were performed to examine six process factors for each photoresist: viscosity, spin acceleration, spin speed, spin time, softbake time, and softbake temperature. Using the results derived from the screening experiments, a more thorough examination of the statistically significant process factors was performed. A full quadratic experimental design was conducted to examine viscosity, spin speed, and spin time coating properties on alignment. This included a characterization of both intra and inter wafer alignment control and alignment process capability. Insight to the different alignment behavior is analyzed in terms of photoresist material properties and the physical nature of the alignment detection system.

Structural, morphological and optical properties of PEDOT:PSS/QDs nano-composite films prepared by spin-casting

NASA Astrophysics Data System (ADS)

Najeeb, Mansoor Ani; Abdullah, Shahino Mah; Aziz, Fakhra; Ahmad, Zubair; Rafique, Saqib; Wageh, S.; Al-Ghamdi, Ahmed A.; Sulaiman, Khaulah; Touati, Farid; Shakoor, R. A.; Al-Thani, N. J.

2016-09-01

This paper describes the structural, morphological and optical properties of the nano-composite of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and quantum dots (QDs). The ZnSe and CdSe QDs have been synthesized, with the aid of Mercaptoacetic acid (MAA), by a colloidal method with an average size of 5 to 7 nm. QDs have been embedded in PEDOT:PSS using a simple solution processing approach and has been deposited as thin films by spin coating technique. The QDs embedded PEDOT:PSS enhances the light absorption spectra of samples, prominently in terms of absorption intensity which may consequently improve sensitivity of the optoelectronic devices.

Biodegradable polymer for sealing porous PEO layer on pure magnesium: An in vitro degradation study

NASA Astrophysics Data System (ADS)

Alabbasi, Alyaa; Mehjabeen, Afrin; Kannan, M. Bobby; Ye, Qingsong; Blawert, Carsten

2014-05-01

An attempt was made to seal the porous silicate-based plasma electrolytic oxidation (PEO) layer on pure magnesium (Mg) with a biodegradable polymer, poly(L-lactide) (PLLA), to delay the localized degradation of magnesium-based implants in body fluid for better in-service mechanical integrity. Firstly, a silicate-based PEO coating on pure magnesium was performed using a pulsed constant current method. In order to seal the pores in the PEO layer, PLLA was coated using a two-step spin coating method. The performance of the PEO-PLLA Mg was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The EIS results showed that the polarization resistance (Rp) of the PEO-PLLA Mg was close to two orders of magnitude higher than that of the PEO Mg. While the corrosion current density (icorr) of the pure Mg was reduced by 65% with the PEO coating, the PEO-PLLA coating reduced the icorr by almost 100%. As expected, the Rp of the PEO-PLLA Mg decreased with increase in exposure time. However, it was noted that the Rp of the PEO-PLLA Mg even after 100 h was six times higher than that of the PEO Mg after 48 h exposure, and did not show any visible localized attack.

Super-Hydrophobic/Icephobic Coatings Based on Silica Nanoparticles Modified by Self-Assembled Monolayers.

PubMed

Liu, Junpeng; Janjua, Zaid A; Roe, Martin; Xu, Fang; Turnbull, Barbara; Choi, Kwing-So; Hou, Xianghui

2016-12-02

A super-hydrophobic surface has been obtained from nanocomposite materials based on silica nanoparticles and self-assembled monolayers of 1 H ,1 H ,2 H ,2 H -perfluorooctyltriethoxysilane (POTS) using spin coating and chemical vapor deposition methods. Scanning electron microscope images reveal the porous structure of the silica nanoparticles, which can trap small-scale air pockets. An average water contact angle of 163° and bouncing off of incoming water droplets suggest that a super-hydrophobic surface has been obtained based on the silica nanoparticles and POTS coating. The monitored water droplet icing test results show that icing is significantly delayed by silica-based nano-coatings compared with bare substrates and commercial icephobic products. Ice adhesion test results show that the ice adhesion strength is reduced remarkably by silica-based nano-coatings. The bouncing phenomenon of water droplets, the icing delay performance and the lower ice adhesion strength suggest that the super-hydrophobic coatings based on a combination of silica and POTS also show icephobicity. An erosion test rig based on pressurized pneumatic water impinging impact was used to evaluate the durability of the super-hydrophobic/icephobic coatings. The results show that durable coatings have been obtained, although improvement will be needed in future work aiming for applications in aerospace.

Fabrication of organic-inorganic perovskite thin films for planar solar cells via pulsed laser deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Yangang; Zhang, Xiaohang; Gong, Yunhui

2016-01-15

We report on fabrication of organic-inorganic perovskite thin films using a hybrid method consisting of pulsed laser deposition (PLD) of lead iodide and spin-coating of methylammonium iodide. Smooth and highly crystalline CH{sub 3}NH{sub 3}PbI{sub 3} thin films have been fabricated on silicon and glass coated substrates with fluorine doped tin oxide using this PLD-based hybrid method. Planar perovskite solar cells with an inverted structure have been successfully fabricated using the perovskite films. Because of its versatility, the PLD-based hybrid fabrication method not only provides an easy and precise control of the thickness of the perovskite thin films, but also offersmore » a straightforward platform for studying the potential feasibility in using other metal halides and organic salts for formation of the organic-inorganic perovskite structure.« less

Preliminary evaluation of an aqueous wax emulsion for controlled-release coating.

PubMed

Walia, P S; Stout, P J; Turton, R

1998-02-01

The purpose of this work was to evaluate the use of an aqueous carnauba wax emulsion (Primafresh HS, Johnson Wax) in a spray-coating process. This involved assessing the effectiveness of the wax in sustaining the release of the drug, theophylline. Second, the process by which the drug was released from the wax-coated pellets was modeled. Finally, a method to determine the optimum blend of pellets with different wax thicknesses, in order to yield a zero-order release profile of the drug, was addressed. Nonpareil pellets were loaded with theophylline using a novel powder coating technique. These drug-loaded pellets were then coated with different levels of carnauba wax in a 6-in. diameter Plexiglas fluid bed with a 3.5-in. diameter Wurster partition. Drug release was measured using a spin-filter dissolution device. The study resulted in continuous carnauba wax coatings which showed sustained drug release profile characteristics typical of a barrier-type, diffusion-controlled system. The effect of varying wax thickness on the release profiles was investigated. It was observed that very high wax loadings would be required to achieve long sustained-release times. The diffusion model, developed to predict the release of the drug, showed good agreement with the experimental data. However, the data exhibited an initial lag-time for drug release which could not be predicted a priori based on the wax coating thickness. A method of mixing pellets with different wax thicknesses was proposed as a way to approximate zero-order release.

Influence Al doped ZnO nanostructure on structural and optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramelan, Ari Handono, E-mail: aramelan@mipa.uns.ac.id; Wahyuningsih, Sayekti; Chasanah, Uswatul

2016-04-19

The preparation of Al-doped ZnO (AZO) thin films prepared by the spin-coating method was reported. Preparation of AZO was conducted by annealing treatment at a temperature of 700°C. While the spin-coating process of AZO thin films were done at 2000 and 3000 rpm respectively. The structural properties of ZnO were determined by X- ray diffraction (XRD) analysis. ZnOnanostructure was formed after annealed at atemperature of 400°C.The morphology of ZnO was determined by Scanning Electron Microscopy (SEM) showed the irregular morphology about 30-50µm in size. Al doped on ZnO influenced the optical properties of those material. Increasing Al contain on ZnO causemore » of shifting to the lower wavelength. The optical properties of the ZnO as well as AZO films showed that higher reflectance on the ultraviolet region so those materials were used as anti-reflecting agent.Al addition significantly enhance the optical transparency and induce the blue-shift in optical bandgap of ZnO films.« less

Electrical, optical and structural properties of transparent conducting Al doped ZnO (AZO) deposited by sol-gel spin coating

NASA Astrophysics Data System (ADS)

Tonny, Kaniz Naila; Rafique, Rosaleena; Sharmin, Afrina; Bashar, Muhammad Shahriar; Mahmood, Zahid Hasan

2018-06-01

Al doped ZnO (AZO) films are fabricated by using sol-gel spin coating method and changes in electrical, optical and structural properties due to variation in film thickness is studied. AZO films provide c-axis orientation along the (002) plane and peak sharpness increased with film thickness is evident from XRD analysis. Conductivity (σ) of AZO films has increased from 2.34 (Siemens/cm) to 20156.27 (Siemens/cm) whereas sheet resistance (Rsh) decreases from 606300 (ohms/sq.) to 2.08 (ohm/sq.) with increase of film thickness from 296 nm to 1030 nm. Optical transmittance (T%) of AZO films is decreased from around 82% to 62% in the visible region. And grain size (D) of AZO thin films has been found to increase from 19.59 nm to 25.25 nm with increase of film thickness. Figure of Merit is also calculated for prepared sample of AZO. Among these four sample of AZO thin films, L-15 sample (having thickness in 895 nm) has provided highest figure of merit which is 5.49*10^-4 (Ω-1).

Improving Efficiency of Multicrystalline Silicon and CIGS Solar Cells by Incorporating Metal Nanoparticles.

PubMed

Jeng, Ming-Jer; Chen, Zih-Yang; Xiao, Yu-Ling; Chang, Liann-Be; Ao, Jianping; Sun, Yun; Popko, Ewa; Jacak, Witold; Chow, Lee

2015-10-08

This work studies the use of gold (Au) and silver (Ag) nanoparticles in multicrystalline silicon (mc-Si) and copper-indium-gallium-diselenide (CIGS) solar cells. Au and Ag nanoparticles are deposited by spin-coating method, which is a simple and low cost process. The random distribution of nanoparticles by spin coating broadens the resonance wavelength of the transmittance. This broadening favors solar cell applications. Metal shadowing competes with light scattering in a manner that varies with nanoparticle concentration. Experimental results reveal that the mc-Si solar cells that incorporate Au nanoparticles outperform those with Ag nanoparticles. The incorporation of suitable concentration of Au and Ag nanoparticles into mc-Si solar cells increases their efficiency enhancement by 5.6% and 4.8%, respectively. Incorporating Au and Ag nanoparticles into CIGS solar cells improve their efficiency enhancement by 1.2% and 1.4%, respectively. The enhancement of the photocurrent in mc-Si solar cells is lower than that in CIGS solar cells, owing to their different light scattering behaviors and material absorption coefficients.

Improving Efficiency of Multicrystalline Silicon and CIGS Solar Cells by Incorporating Metal Nanoparticles

PubMed Central

Jeng, Ming-Jer; Chen, Zih-Yang; Xiao, Yu-Ling; Chang, Liann-Be; Ao, Jianping; Sun, Yun; Popko, Ewa; Jacak, Witold; Chow, Lee

2015-01-01

This work studies the use of gold (Au) and silver (Ag) nanoparticles in multicrystalline silicon (mc-Si) and copper-indium-gallium-diselenide (CIGS) solar cells. Au and Ag nanoparticles are deposited by spin-coating method, which is a simple and low cost process. The random distribution of nanoparticles by spin coating broadens the resonance wavelength of the transmittance. This broadening favors solar cell applications. Metal shadowing competes with light scattering in a manner that varies with nanoparticle concentration. Experimental results reveal that the mc-Si solar cells that incorporate Au nanoparticles outperform those with Ag nanoparticles. The incorporation of suitable concentration of Au and Ag nanoparticles into mc-Si solar cells increases their efficiency enhancement by 5.6% and 4.8%, respectively. Incorporating Au and Ag nanoparticles into CIGS solar cells improve their efficiency enhancement by 1.2% and 1.4%, respectively. The enhancement of the photocurrent in mc-Si solar cells is lower than that in CIGS solar cells, owing to their different light scattering behaviors and material absorption coefficients. PMID:28793599

Solution-processed zinc oxide nanoparticles/single-walled carbon nanotubes hybrid thin-film transistors

NASA Astrophysics Data System (ADS)

Liu, Fangmei; Sun, Jia; Qian, Chuan; Hu, Xiaotao; Wu, Han; Huang, Yulan; Yang, Junliang

2016-09-01

Solution-processed thin-film transistors (TFTs) are the essential building blocks for manufacturing the low-cost and large-area consumptive electronics. Herein, solution-processed TFTs based on the composites of zinc oxide (ZnO) nanoparticles and single-walled carbon nanotubes (SWCNTs) were fabricated by the methods of spin-coating and doctor-blading. Through controlling the weight of SWCNTs, the ZnO/SWCNTs TFTs fabricated by spin-coating demonstrated a field-effect mobility of 4.7 cm2/Vs and a low threshold voltage of 0.8 V, while the TFTs devices fabricated by doctor-blading technique showed reasonable electrical performance with a mobility of 0.22 cm2/Vs. Furthermore, the ion-gel was used as an efficient electrochemical gate dielectric because of its large electric double-layer capacitance. The operating voltage of all the TFTs devices is as low as 4.0 V. The research suggests that ZnO/SWCNTs TFTs have the potential applications in low-cost, large-area and flexible consumptive electronics, such as chemical-biological sensors and smart label.

Manipulation of ZnO composition affecting electrical properties of MEH-PPV: ZnO nanocomposite thin film via spin coating for OLEDs application

NASA Astrophysics Data System (ADS)

Azhar, N. E. A.; Shariffudin, S. S.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

Recent investigations of the promising materials for optoelectronic have been demonstrated by introducing n-type inorganic material into conjugated polymer. Morphology, optical and electrical of nanocomposites thin films based on poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and zinc oxide (ZnO) nanotetrapods with various ZnO composition (0 wt% to 0.4 wt%) have been investigated. The MEH-PPV: ZnO nanocomposite thin film was deposited using spin-coating method. Surface morphology was characterized using field emission scanning electron microscopy and shows the uniform dispersion of MEH-PPV and ZnO phases for sample deposited at 0.2 wt%. The photoluminescence (PL) spectra shows the visible emission intensities increased when the ZnO composition increased. The current-voltage (I-V) measurement shows the highest conductivity of nanocomposite thin film deposited at 0.2 wt% of ZnO is 7.40 × 10-1 S. cm-1. This study will provide better performance and suitable for optoelectronic device especially OLEDs application.

Photobleachable Diazonium Salt-Phenolic Resin Two-Layer Resist System

NASA Astrophysics Data System (ADS)

Uchino, Shou-ichi; Iwayanagi, Takao; Hashimoto, Michiaki

1988-01-01

This article describes a new negative two-layer photoresist system formed by a simple, successive spin-coating method. An aqueous acetic acid solution of diazonium salt and poly(N-vinylpyrrolidone) is deposited so as to contact a phenolic resin film spin-coated on a silicon wafer. The diazonium salt diffuses into the phenolic resin layer after standing for several minutes. The residual solution on the phenolic resin film doped with diazonium salt is spun to form the diazonium salt-poly(N-vinylpyrrolidone) top layer. This forms a uniform two-layer resist without phase separation or striation. Upon UV exposure, the diazonium salt in the top layer bleaches to act as a CEL dye, while the diazonium salt in the bottom layer decomposes to cause insolubilization. Half μm line-and-space patterns are obtained with an i-line stepper using 4-diazo-N,N-dimethylaniline chloride zinc chloride double salt as the diazonium salt and a cresol novolac resin for the bottom polymer layer. The resist formation processes, insolubilization mechanism, and the resolution capability of the new two-layer resist are discussed.

Electrodeposition of organic-inorganic tri-halide perovskites solar cell

NASA Astrophysics Data System (ADS)

Charles, U. A.; Ibrahim, M. A.; Teridi, M. A. M.

2018-02-01

Perovskite (CH3NH3PbI3) semiconductor materials are promising high-performance light energy absorber for solar cell application. However, the power conversion efficiency of perovskite solar cell is severely affected by the surface quality of the deposited thin film. Spin coating is a low-cost and widely used deposition technique for perovskite solar cell. Notably, film deposited by spin coating evolves surface hydroxide and defeats from uncontrolled precipitation and inter-diffusion reaction. Alternatively, vapor deposition (VD) method produces uniform thin film but requires precise control of complex thermodynamic parameters which makes the technique unsuitable for large scale production. Most deposition techniques for perovskite require tedious surface optimization to improve the surface quality of deposits. Optimization of perovskite surface is necessary to significantly improve device structure and electrical output. In this review, electrodeposition of perovskite solar cell is demonstrated as a scalable and reproducible technique to fabricate uniform and smooth thin film surface that circumvents the need for high vacuum environment. Electrodeposition is achieved at low temperatures, supports precise control and optimization of deposits for efficient charge transfer.

Analysis of Crystal Structure of Fe3O4 Thin Films Based on Iron Sand Growth by Spin Coating Method

NASA Astrophysics Data System (ADS)

Rianto, D.; Yulfriska, N.; Murti, F.; Hidayati, H.; Ramli, R.

2018-04-01

Recently, iron sand used as one of base materials in the steel industry. However, the content of iron sand can be used as starting materials in sensor technology in the form of thin films. In this paper, we report the analysis of crystal structure of magnetite thin film based on iron sand from Tiram’s Beach. The magnetic content of sand separated by a permanent magnet, then it was milled at 30 hours milling time. In order to increase the purity of magnetite, it washed after milling using aquades under magnetic separation by a magnet permanent. The thin film has been prepared using iron (III) nitrate by sol–gel technique. The precursor is resulted by dissolving magnetite in oxalic acid and nitric acid. Then, solution of iron (III) nitrate dissolved in ethylene glycol was applied on glass substrates by spin coating. The X-Ray Diffraction is operated thin film characterization. The structure of magnetite has been studied based on X-Ray Peaks that correspond to magnetite content of thin films.

Synthesis and characterization of cadmium sulphide thin films prepared by spin coating

NASA Astrophysics Data System (ADS)

Chodavadiya, Nisarg; Chapanari, Amisha; Zinzala, Jignesh; Ray, Jaymin; Pandya, Samir

2018-05-01

An II-VI group semiconductor is Wide band gap materials and has been widely studied due to their fundamental optical, structural, and electrical properties. Cadmium sulphide (CdS) is one of the most emerged materials in II-VI group. It has many applications such as buffer later in photovoltaic cell, multilayer light emitting diodes, optical filters, thin film field effect transistors, gas sensors, light detectors etc. It is fundamentally an n-type material with an optical band gap of 2.4 eV. Owing to these properties we had studied CdS thin films synthesis and characterized by Raman, Ultraviolet - Visible spectroscopy (UV-VIS) and Hot probe method. CdS thin films were prepared by spin coating of the Cadmium-thiourea precursor solution. Visual inspection after 20 minute thermolysis time the films were looks uniform and shiny pale yellow in color. Raman confirms the A1 vibration of pure CdS. UV-VIS gives the band gap about 2.52 eV, which confirms the formation of nanocrystalline form of CdS. Finally, hot probe signifies the n-type conductivity of the CdS film.

Broadband antireflective silicon nanostructures produced by spin-coated Ag nanoparticles

PubMed Central

2014-01-01

We report the fabrication of broadband antireflective silicon (Si) nanostructures fabricated using spin-coated silver (Ag) nanoparticles as an etch mask followed by inductively coupled plasma (ICP) etching process. This fabrication technique is a simple, fast, cost-effective, and high-throughput method, making it highly suitable for mass production. Prior to the fabrication of Si nanostructures, theoretical investigations were carried out using a rigorous coupled-wave analysis method in order to determine the effects of variations in the geometrical features of Si nanostructures to obtain antireflection over a broad wavelength range. The Ag ink ratio and ICP etching conditions, which can affect the distribution, distance between the adjacent nanostructures, and height of the resulting Si nanostructures, were carefully adjusted to determine the optimal experimental conditions for obtaining desirable Si nanostructures for practical applications. The Si nanostructures fabricated using the optimal experimental conditions showed a very low average reflectance of 8.3%, which is much lower than that of bulk Si (36.8%), as well as a very low reflectance for a wide range of incident angles and different polarizations over a broad wavelength range of 300 to 1,100 nm. These results indicate that the fabrication technique is highly beneficial to produce antireflective structures for Si-based device applications requiring low light reflection. PMID:24484636

Electrical properties of solution-deposited ZnO thin-film transistors by low-temperature annealing.

PubMed

Lim, Chul; Oh, Ji Young; Koo, Jae Bon; Park, Chan Woo; Jung, Soon-Won; Na, Bock Soon; Chu, Hye Yong

2014-11-01

Flexible oxide thin-film transistors (Oxide-TFTs) have emerged as next generation transistors because of their applicability in electronic device. In particular, the major driving force behind solution-processed zinc oxide film research is its prospective use in printing for electronics. A low-temperature process to improve the performance of solution-processed n-channel ZnO thin-film transistors (TFTs) fabricated via spin-coating and inkjet-printing is introduced here. ZnO nanoparticles were synthesized using a facile sonochemical method that was slightly modified based on a previously reported method. The influence of the annealing atmosphere on both nanoparticle-based TFT devices fabricated via spin-coating and those created via inkjet printing was investigated. For the inkjet-printed TFTs, the characteristics were improved significantly at an annealing temperature of 150 degrees C. The field effect mobility, V(th), and the on/off current ratios were 3.03 cm2/Vs, -3.3 V, and 10(4), respectively. These results indicate that annealing at 150 degrees C 1 h is sufficient to obtain a mobility (μ(sat)) as high as 3.03 cm2/Vs. Also, the active layer of the solution-based ZnO nanoparticles allowed the production of high-performance TFTs for low-cost, large-area electronics and flexible devices.

Regulation of the forming process and the set voltage distribution of unipolar resistance switching in spin-coated CoFe2O4 thin films.

PubMed

Mustaqima, Millaty; Yoo, Pilsun; Huang, Wei; Lee, Bo Wha; Liu, Chunli

2015-01-01

We report the preparation of (111) preferentially oriented CoFe2O4 thin films on Pt(111)/TiO2/SiO2/Si substrates using a spin-coating process. The post-annealing conditions and film thickness were varied for cobalt ferrite (CFO) thin films, and Pt/CFO/Pt structures were prepared to investigate the resistance switching behaviors. Our results showed that resistance switching without a forming process is preferred to obtain less fluctuation in the set voltage, which can be regulated directly from the preparation conditions of the CFO thin films. Therefore, instead of thicker film, CFO thin films deposited by two times spin-coating with a thickness about 100 nm gave stable resistance switching with the most stable set voltage. Since the forming process and the large variation in set voltage have been considered as serious obstacles for the practical application of resistance switching for non-volatile memory devices, our results could provide meaningful insights in improving the performance of ferrite material-based resistance switching memory devices.

Surface Modification of Zirconia Substrate by Calcium Phosphate Particles Using Sol-Gel Method.

PubMed

Jin, So Dam; Um, Sang Cheol; Lee, Jong Kook

2015-08-01

Surface modification with a biphasic composition of hydroxyapatite (HA) and tricalcium phosphate (TCP) was performed on a zirconia substrate using a sol-gel method. An initial calcium phosphate sol was prepared by mixing a solution of Ca(NO3)2 · 4H20 and (C2H5O)3P(O), while both porous and dense zirconia were used as substrates. The sol-gel coating was performed using a spin coater. The coated porous zirconia substrate was re-sintered at 1350 °C 2 h, while coated dense zirconia substrate was heat-treated at 750 °C 1 h. The microstructure of the resultant HA/TCP coatings was found to be dependent on the type of zirconia substrate used. With porous zirconia as a starting substrate, numerous isolated calcium phosphate particles (TCP and HA) were uniformly dispersed on the surface, and the particle size and covered area were dependent on the viscosity of the calcium phosphate sol. Conversely, when dense zirconia was used as a starting substrate, a thick film of nano-sized HA particles was obtained after heat treatment, however, substantial agglomeration and cracking was also observed.

In situ chemical oxidative polymerization preparation of poly(3,4-ethylenedioxythiophene)/graphene nanocomposites with enhanced thermoelectric performance.

PubMed

Xu, Kongli; Chen, Guangming; Qiu, Dong

2015-05-01

Three different in situ chemical oxidative polymerization routes, that is, (A) spin-coating and subsequent liquid layer polymerization, (B) spin-coating followed by vapor phase polymerization, and (C) in situ polymerization and then post-treatment by immersion in ethylene glycol (EG), have been developed to achieve poly(3,4-ethylenedioxythiophene)/reduced graphene oxide (PEDOT/rGO) nanocomposites. As demonstrated by scanning electron microscopic and energy-dispersive X-ray spectroscopic techniques, PEDOT has been successfully coated on the surface of the rGO nanosheets by each of the three preparation routes. Importantly, all of the nanocomposites display a greatly enhanced thermoelectric performance (power factors) relative to those of the corresponding neat PEDOT. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Humidity scanning quartz crystal microbalance with dissipation monitoring setup for determination of sorption-desorption isotherms and rheological changes

NASA Astrophysics Data System (ADS)

Björklund, Sebastian; Kocherbitov, Vitaly

2015-05-01

A new method to determine water sorption-desorption isotherms with high resolution in the complete range of water activities (relative humidities) is presented. The method is based on quartz crystal microbalance with dissipation monitoring (QCM-D). The QCM-D is equipped with a humidity module in which the sample film is kept in air with controlled humidity. The experimental setup allows for continuous scanning of the relative humidity from either dry to humid conditions or vice versa. The amount of water sorbed or desorbed from the sample is determined from the resonance frequencies of the coated quartz sensor, via analysis of the overtone dependence. In addition, the method allows for characterization of hydration induced changes of the rheological properties from the dissipation data, which is closely connected to the viscoelasticity of the film. The accuracy of the humidity scanning setup is confirmed in control experiments. Sorption-desorption isotherms of pig gastric mucin and lysozyme, obtained by the new method, show good agreement with previous results. Finally, we show that the deposition technique used to coat the quartz sensor influences the QCM-D data and how this issue can be used to obtain further information on the effect of hydration. In particular, we demonstrate that spin-coating represents an attractive alternative to obtain sorption-desorption isotherms, while drop-coating provides additional information on changes of the rheological properties during hydration.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Björklund, Sebastian, E-mail: sebastianbjorklund@gmail.com; Kocherbitov, Vitaly; Biofilms—Research Center for Biointerfaces, Malmö University, Malmö

A new method to determine water sorption-desorption isotherms with high resolution in the complete range of water activities (relative humidities) is presented. The method is based on quartz crystal microbalance with dissipation monitoring (QCM-D). The QCM-D is equipped with a humidity module in which the sample film is kept in air with controlled humidity. The experimental setup allows for continuous scanning of the relative humidity from either dry to humid conditions or vice versa. The amount of water sorbed or desorbed from the sample is determined from the resonance frequencies of the coated quartz sensor, via analysis of the overtonemore » dependence. In addition, the method allows for characterization of hydration induced changes of the rheological properties from the dissipation data, which is closely connected to the viscoelasticity of the film. The accuracy of the humidity scanning setup is confirmed in control experiments. Sorption-desorption isotherms of pig gastric mucin and lysozyme, obtained by the new method, show good agreement with previous results. Finally, we show that the deposition technique used to coat the quartz sensor influences the QCM-D data and how this issue can be used to obtain further information on the effect of hydration. In particular, we demonstrate that spin-coating represents an attractive alternative to obtain sorption-desorption isotherms, while drop-coating provides additional information on changes of the rheological properties during hydration.« less

Versatility of Alkyne-Modified Poly(Glycidyl Methacrylate) Layers for Click Reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soto-Cantu, Dr. Erick; Lokitz, Bradley S; Hinestrosa Salazar, Juan Pablo

2011-01-01

Functional soft interfaces are of interest for a variety of technologies. We describe three methods for preparing substrates with alkyne groups, which show versatility for 'click' chemistry reactions. Two of the methods have the same root: formation of thin, covalently attached, reactive interfacial layers of poly(glycidyl methacrylate) (PGMA) via spin coating onto silicon wafers followed by reactive modification with either propargylamine or 5-hexynoic acid. The amine or the carboxylic acid moieties react with the epoxy groups of PGMA, creating interfacial polymer layers decorated with alkyne groups. The third method consists of using copolymers comprising glycidyl methacrylate and propargyl methacrylate (pGP).more » The pGP copolymers are spin coated and covalently attached on silicon wafers. For each method, we investigate the factors that control film thickness and content of alkyne groups using ellipsometry, and study the nanophase structure of the films using neutron reflectometry. Azide-terminated polymers of methacrylic acid and 2-vinyl-4,4-dimethylazlactone synthesized via reversible addition-fragmentation chain transfer polymerization were attached to the alkyne-modified substrates using 'click' chemistry, and grafting densities in the range of 0.007-0.95 chains nm{sup -2} were attained. The maximum density of alkyne groups attained by functionalization of PGMA with propargylamine or 5-hexynoic acid was approximately 2 alkynes nm{sup -3}. The alkyne content obtained by the three decorating approaches was sufficiently high that it was not the limiting factor for the click reaction of azide-capped polymers.« less

Fast Printing and In-Situ Morphology Observation of Organic Photovoltaics using Slot-Die Coating

NASA Astrophysics Data System (ADS)

Liu, Feng; Ferdous, Sunzida; Wang, Cheng; Hexamer, Alexander; Russell, Thomas; Cheng Wang Collaboration; Thomas Russell Team

2014-03-01

The solvent-processibility of polymer semiconductors is a key advantage for the fabrication of large area, organic bulk-heterojunction (BHJ) photovoltaic devices. Most reported power conversion efficiencies (PCE) are based on small active areas, fabricated by spin-coating technique. In general, this does not reflect device fabrication in an industrial setting. To realize commercial viability, devices need to be fabricated in a roll-to-roll fashion. The evolution of the morphology associated with different processing parameters, like solvent choice, concentration and temperature, needs to be understood and controlled. We developed a mini slot-die coater, to fabricate BHJ devices using various low band gap polymers mixed with phenyl-C71-butyric acid methyl ester (PCBM). Solvent choice, processing additives, coating rate and coating temperatures were used to control the final morphology. Efficiencies comparable to lab-setting spin-coated devices are obtained. The evolution of the morphology was monitored by in situ scattering measurements, detecting the onset of the polymer chain packing in solution that led to the formation of a fibrillar network in the film.

Solvent-induced changes in PEDOT:PSS films for organic electrochemical transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Shiming; Kumar, Prajwal; Nouas, Amel Sarah

2015-01-01

Organic electrochemical transistors based on the conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) are of interest for several bioelectronic applications. In this letter, we investigate the changes induced by immersion of PEDOT:PSS films, processed by spin coating from different mixtures, in water and other solvents of different polarities. We found that the film thickness decreases upon immersion in polar solvents, while the electrical conductivity remains unchanged. The decrease in film thickness is minimized via the addition of a cross-linking agent to the mixture used for the spin coating of the films.

Effects of Humidity and Surface on Photoalignment of Brilliant Yellow

DTIC Science & Technology

2016-10-14

RH) ranges: 27-30%, 40-45%, 46-50%, 50-58%, 52-59%, and 61-65%. After spin- coating, the resulting BY films were baked at 120°C for 10min to evaporate...polyimide (PI2555) film. To prepare PVA film, 1% PVA water solution was spin- coated onto UV-Ozone cleaned glass at 1500rpm for 30s, followed by baking at...by soft baking at 95°C for 1min and then hard baking at 275°C for 1 hour. About 0.25ml BY-DMF solution was flooded onto the different substrates (1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, Min-Cherl; Zhang, Dongrong; Nikiforov, Gueorgui O.

Ultrathin (<6 nm) polycrystalline films of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-P) are deposited with a two-step spin-coating process. The influence of spin-coating conditions on morphology of the resulting film was examined by atomic force microscopy. Film thickness and RMS surface roughness were in the range of 4.0–6.1 and 0.6–1.1 nm, respectively, except for small holes. Polycrystalline structure was confirmed by grazing incidence x-ray diffraction measurements. Near-edge x-ray absorption fine structure measurements suggested that the plane through aromatic rings of TIPS-P molecules was perpendicular to the substrate surface.

Multi-Layer Coating of Ultrathin Polymer Films on Nanoparticles of Alumina by a Plasma Treatment

DTIC Science & Technology

2001-01-01

Proc. Vol. 635 © 2001 Materials Research Society Multi-Layer Coating of Ultrathin Polymer Films on Nanoparticles of Alumina by a Plasma Treatment Donglu...interconnected organic and inorganic networks results in coatings with a very low permeability for gases and liquids. Hybrid materials are very suitable for... materials consist of a clear alcoholic solution that can easily be processed by classical application techniques such as dipping, spraying, or spin coating

Humidity sensitive polymers In solution processed adjustable pore-volume Cu(In,Ga)S2 photocathodes for solar hydrogen production

NASA Astrophysics Data System (ADS)

Zhang, Chuan; Luo, Wenjun; Wen, Xin; Guan, Zhongjie; Zou, Zhigang

2017-11-01

P-type Cu(In,Ga)S2 semiconductors are promising candidates to be used as photocathodes for solar water splitting. Porous structures have been widely used to improve the performances of photoelectrodes due to good minority carrier transport. However, a porous photoelectrode has longer transport distance of majority carriers, which limits its performance. Controlling pore volume of a photoelectrode can balance minority and majority carrier transport and improve the performance. Here, a porous Cu(In,Ga)S2 film is prepared by facile spin-coating method. The pore volume of Cu(In,Ga)S2 film is controlled by adjusting relative humidity (RH) of air during spin-coating process. Further studies suggest that polyvinyl acetate (PVAc) in precursor solution is a humidity sensitive polymer and plays a key role to form different pore volume. The 40% RH sample has the best performance due to its optimum pore volume. After further coated with CdS surface passivation layer and Pt electrocatalyst on the surface, a 40% RH Cu(In,Ga)S2 photocathode indicates a photocurrent density of 8.6 mA cm-2 at 0 V RHE, which is one of the highest photocurrents of Cu(In,Ga)S2 photocathodes. This new strategy for adjusting pore volume is also suitable to prepare other solution-processed inorganic materials.

Fabrication of 10 μm-scale conductive Cu patterns by selective laser sintering of Cu complex ink

NASA Astrophysics Data System (ADS)

Min, Hyungsuk; Lee, Byoungyoon; Jeong, Sooncheol; Lee, Myeongkyu

2017-02-01

A Cu complex ink was synthesized using copper formate as a precursor and its potential for laser patterning was investigated. The Cu ink was spin-coated onto a substrate and the coated film was space-selectively sintered using a nanosecond-pulsed ultraviolet laser. The unexposed Cu ink could be removed from the film by rinsing it with the dispersing agent used to synthesize the ink, disclosing a conductive Cu pattern. A minimum resistivity of 8.46×10-5 Ω cm was obtained for the Cu lines with 10-20 μm widths. The feasibility of this method for metallization was demonstrated by fabricating a complex Cu electric circuit on an indium tin oxide-coated glass substrate. The selective laser sintering approach provides a simple, cost-effective alternative to conventional lithography for the production of electrode or metallization patterns.

A H2-evolving photocathode based on direct sensitization of MoS3 with an organic photovoltaic cell

PubMed Central

Bourgeteau, Tiphaine; Tondelier, Denis; Geffroy, Bernard; Brisse, Romain; Laberty-Robert, Christel; Campidelli, Stéphane; de Bettignies, Rémi; Artero, Vincent; Palacin, Serge; Jousselme, Bruno

2013-01-01

An organic solar cell based on a poly-3-hexylthiophene (P3HT): phenyl-C61-butyric acid (PCBM) bulk hetero-junction was directly coupled with molybdenum sulfide resulting in the design of a new type of photocathode for the production of hydrogen. Both the light-harvesting system and the catalyst were deposited by low-cost solution-processed methods, i.e. spin coating and spray coating respectively. Spray-coated MoS3 films are catalytically active in strongly acidic aqueous solutions with the best efficiencies for thicknesses of 40 to 90 nm. The photocathodes display photocurrents higher than reference samples, without catalyst or without coupling with a solar cell. Analysis by gas chromatography confirms the light-induced hydrogen evolution. The addition of titanium dioxide in the MoS3 film enhances electron transport and collection within thick films and therefore the performance of the photocathode. PMID:24404434

Facile fabrication of uniaxial nanopatterns on shape memory polymer substrates using a complete bottom-up approach

NASA Astrophysics Data System (ADS)

Chen, Zhongbi; Krishnaswamy, Sridhar

2014-03-01

In earlier work, we have demonstrated an assisted self-assembly fabrication method for unidirectional submicron patterns using pre-programmed shape memory polymers (SMP) as the substrate in an organic/inorganic bilayer structure. In this paper, we propose a complete bottom-up method for fabrication of uniaxial wrinkles whose wavelength is below 300 nm. The method starts with using the aforementioned self-assembled bi-layer wrinkled surface as the template to make a replica of surface wrinkles on a PDMS layer which is spin-coated on a pre-programmed SMP substrate. When the shape recovery of the substrate is triggered by heating it to its transition temperature, the substrate has been programmed in such a way that it shrinks uniaxially to return to its permanent shape. Consequently, the wrinkle wavelength on PDMS reduces accordingly. A subsequent contact molding process is carried out on the PDMS layer spin-coated on another pre-programmed SMP substrate, but using the wrinkled PDMS surface obtained in the previous step as the master. By activating the shape recovery of the substrate, the wrinkle wavelength is further reduced a second time in a similar fashion. Our experiments showed that the starting wavelength of 640 nm decreased to 290 nm after two cycles of recursive molding. We discuss the advantages and limitations of our recursive molding approach compared to the prevalent top-down fabrication methods represented by lithography. The present study is expected to o er a simple and cost-e ective fabrication method of nano-scale uniaxial wrinkle patterns with the potential for large-scale mass-production.

Structural and optical studies on spin coated ZnO-graphene conjugated thin films

NASA Astrophysics Data System (ADS)

Srinatha, N.; Angadi, Basavaraj; Son, D. I.; Choi, W. K.

2018-05-01

ZnO-Graphene conjugated thin films were prepared using spin coating technique for different spin rates. Prior to the deposition, ZnO-Graphene nanoparticles were synthesized and their particle size and conjugation was studied through Transmission electron microscope (TEM). The deposited films were characterized using grazing incidence x-ray diffractometer (GIXRD), atomic force microscope (AFM) and UV-Visible spectrometer for their crystallinity, surface topographic features and optical properties. GIXRD patterns confirms the presence of both ZnO and Graphene related crystalline peaks supports the TEM results, which shows the quasi core-shell type conjugation of ZnO-Graphene particles. The crystallinity as well as thickness of the films found to decrease with increase of spin rate. AFM results reveal the uniform, smooth and homogeneity of films and also good adhesivity of ZnO-Graphene with glass substrates. No significant change in the transmittance and absorption with spin rate is observed, while the band gap energy found to decrease due to the reduction in the thickness of the films and conjugation of ZnO-Graphene. All films exhibit˜90 % transmittance in the visible wavelength region, could be potential candidates for optoelectronics and transparent conducting oxide (TCO) applications.

Preparation of nickel oxide thin films at different annealing temperature by sol-gel spin coating method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdullah, M. A. R., E-mail: ameerridhwan89@gmail.com; Mamat, M. H., E-mail: hafiz-030@yahoo.com; Ismail, A. S., E-mail: kyrin-samaxi@yahoo.com

2016-07-06

Preparation of NiO thin films at different annealing temperature by sol-gel method was conducted to synthesize the quality of the surface thin films. The effects of annealing temperature on the surface topology were systematically investigated. Our studies confirmed that the surface roughness of the thin films was increased whenever annealing temperature was increase. NiO thin films morphology structure analysis was confirmed by field emission scanning electron microscope. Surface roughness of the thin films was investigated by atomic force microscopy.

Preparation of superhydrophobic and transparent micro-nano hybrid coatings from polymethylhydroxysiloxane and silica ormosil aerogels

NASA Astrophysics Data System (ADS)

Nagappan, Saravanan; Park, Jin Joo; Park, Sung Soo; Ha, Chang-Sik

2014-12-01

Superhydrophobic and transparent polymethylhydroxysiloxane (PMHOS)/silica ormosil aerogel hybrids were prepared successfully by mixing of PMHOS with various weight percentages of silica ormosil aerogels (as synthesized from methyltriethoxysilane (MTES) and methyltrimethoxysilane (MTMS) precursors) in separate seal perfume glass vials. The hybrids were spin coated on glass substrate at 1000 rpm for 60 seconds and used for further analysis. The surface morphology and chemical compositions of the hybrids were analyzed by high resolution scanning electron microscopy, high resolution transmission electron microscopy, atomic force spectroscopy, adsorption and desorption isotherm, and X-ray photoelectron spectroscopy. The transparency, thermal decomposition and static contact angle (SCA) of each sample were measured by UV-Visible spectrophotometer, TGA and drop shape analysis system, respectively. The spin coated substrates showed good superhydrophobic properties, thermal stability as well as transparency on the glass substrates.

Investigation of Anti-Relaxation Coatings for Alkali-Metal Vapor Cells using Surface Science Techniques

DTIC Science & Technology

2011-02-01

worldwide. Lawrence Berkeley National Laboratory Peer Reviewed Title: Investigation of anti-Relaxation coatings for alkali-metal vapor cells using ...2010 Abstract: Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of antirelaxation surface coatings in order to...preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an

Correlation between Hierarchical Structure and Processing Control of Large-area Spray-coated Polymer Solar Cells toward High Performance

PubMed Central

Huang, Yu-Ching; Tsao, Cheng-Si; Cha, Hou-Chin; Chuang, Chih-Min; Su, Chun-Jen; Jeng, U-Ser; Chen, Charn-Ying

2016-01-01

The formation mechanism of a spray-coated film is different from that of a spin-coated film. This study employs grazing incidence small- and wide-angle X-ray Scattering (GISAXS and GIWAXS, respectively) quantitatively and systematically to investigate the hierarchical structure and phase-separated behavior of a spray-deposited blend film. The formation of PCBM clusters involves mutual interactions with both the P3HT crystal domains and droplet boundary. The processing control and the formed hierarchical structure of the active layer in the spray-coated polymer/fullerene blend film are compared to those in the spin-coated film. How the different post-treatments, such as thermal and solvent vapor annealing, tailor the hierarchical structure of the spray-coated films is quantitatively studied. Finally, the relationship between the processing control and tailored BHJ structures and the performance of polymer solar cell devices is established here, taking into account the evolution of the device area from 1 × 0.3 and 1 × 1 cm2. The formation and control of the special networks formed by the PCBM cluster and P3HT crystallites, respectively, are related to the droplet boundary. These structures are favorable for the transverse transport of electrons and holes. PMID:26817585

Single crystal growth in spin-coated films of polymorphic phthalocyanine derivative under solvent vapor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Higashi, T.; Ohmori, M.; Ramananarivo, M. F.

2015-12-01

The effects of solvent vapor on spin-coated films of a polymorphic phthalocyanine derivative were investigated. Growth of single crystal films via redissolving organic films under solvent vapor was revealed by in situ microscopic observations of the films. X-ray diffraction measurement of the films after exposing to solvent vapor revealed the phase transition of polymorphs under solvent vapor. The direction of crystal growth was clarified by measuring the crystal orientation in a grown monodomain film. The mechanism of crystal growth based on redissolving organic films under solvent vapor was discussed in terms of the different solubilities of the polymorphs.

Extremely low amplified spontaneous emission threshold and blue electroluminescence from a spin-coated octafluorene neat film

NASA Astrophysics Data System (ADS)

Kim, D.-H.; Sandanayaka, A. S. D.; Zhao, L.; Pitrat, D.; Mulatier, J. C.; Matsushima, T.; Andraud, C.; Ribierre, J. C.; Adachi, C.

2017-01-01

We report on the photophysical, amplified spontaneous emission (ASE), and electroluminescence properties of a blue-emitting octafluorene derivative in spin-coated films. The neat film shows an extremely low ASE threshold of 90 nJ/cm2, which is related to its high photoluminescence quantum yield of 87% and its large radiative decay rate of 1.7 × 109 s-1. Low-threshold organic distributed feedback semiconductor lasers and fluorescent organic light-emitting diodes with a maximum external quantum efficiency as high as 4.4% are then demonstrated, providing evidence that this octafluorene derivative is a promising candidate for organic laser applications.

Observation of sub-100-fs optical response from spin-coated films of squarylium dye J aggregates

NASA Astrophysics Data System (ADS)

Furuki, Makoto; Tian, Minquan; Sato, Yasuhiro; Pu, Lyong Sun; Kawashima, Hitoshi; Tatsuura, Satoshi; Wada, Osamu

2001-04-01

For spin-coated films of squarylium dye J aggregates, ultrafast nonlinear optical responses were investigated by pump-probe measurements. By using a broadband mode-locked titanium:sapphire laser, we succeeded in observing the optical response with a time resolution of better than 60 fs. Time-resolved transmission data are shown for different excitation wavelengths, resonant to the excitonic absorption band and off-resonant. Relaxation times of the absorption saturation were evaluated to be 140 fs (fast component) and 950 fs (slow component) in the case of resonant excitation and 98 fs in the case of off-resonant excitation.

Copper-Zinc-Tin-Sulfur Thin Film Using Spin-Coating Technology

PubMed Central

Yeh, Min-Yen; Lei, Po-Hsun; Lin, Shao-Hsein; Yang, Chyi-Da

2016-01-01

Cu2ZnSnS4 (CZTS) thin films were deposited on glass substrates by using spin-coating and an annealing process, which can improve the crystallinity and morphology of the thin films. The grain size, optical gap, and atomic contents of copper (Cu), zinc (Zn), tin (Sn), and sulfur (S) in a CZTS thin film absorber relate to the concentrations of aqueous precursor solutions containing copper chloride (CuCl2), zinc chloride (ZnCl2), tin chloride (SnCl2), and thiourea (SC(NH2)2), whereas the electrical properties of CZTS thin films depend on the annealing temperature and the atomic content ratios of Cu/(Zn + Sn) and Zn/Sn. All of the CZTS films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS), Raman spectroscopy, and Hall measurements. Furthermore, CZTS thin film was deposited on an n-type silicon substrate by using spin-coating to form an Mo/p-CZTS/n-Si/Al heterostructured solar cell. The p-CZTS/n-Si heterostructured solar cell showed a conversion efficiency of 1.13% with Voc = 520 mV, Jsc = 3.28 mA/cm2, and fill-factor (FF) = 66%. PMID:28773647

Morphological, structural and optical properties of MEH-PPV: PC70BM nanocomposite film

NASA Astrophysics Data System (ADS)

Mhamdi, Asya; Sweii, Fatma ben Slama; Saidi, Hamza; Saidi, Faouzi; Bouazizi, Abdelaziz

2018-05-01

In this report, the influence of annealing temperature and spin coating speed on the structural and morphological properties of a blend of poly (2-methoxy-5-(2-ethyl-oxy)-p-phenylene-vinylene) (MEH-PPV) and [6-6]-phenyl-C71-butyric acid methyl ester (PC70BM) layer has been investigated. The photoactive layer (MEH-PPV: PC70BM) was deposited on ZnO film deposited on top of indium tin oxide (ITO) substrate by spin-coating. The effect of spin coating speed via atomic force microscope (AFM) leads to conclude that high speed is favorable for a good homogeneity of the film surface and good aggregates dispersion. The optimized structure was studied by varying the annealing temperatures using X-ray diffraction (XRD). The XRD analysis indicates that annealing treatment promoted the ordered aggregation and crystallization of MEH-PPV: PC70BM films. Indeed, the blend ratio effect on the optical properties of MEH-PPV: PC70BM thin film was investigated. While, the effect of incorporation of PC70BM on the optical properties was studied using UV-Vis and photoluminescence (PL) measurement. We conclude that MEH-PPV: PC70BM (1:3) film leads to high charge transfer rate.

Fabrication of wafer-scale nanopatterned sapphire substrate through phase separation lithography

NASA Astrophysics Data System (ADS)

Guo, Xu; Ni, Mengyang; Zhuang, Zhe; Dai, Jiangping; Wu, Feixiang; Cui, Yushuang; Yuan, Changsheng; Ge, Haixiong; Chen, Yanfeng

2016-04-01

A phase separation lithography (PSL) based on polymer blend provides an extremely simple, low-cost, and high-throughput way to fabricate wafer-scale disordered nanopatterns. This method was introduced to fabricate nanopatterned sapphire substrates (NPSSs) for GaN-based light-emitting diodes (LEDs). The PSL process only involved in spin-coating of polystyrene (PS)/polyethylene glycol (PEG) polymer blend on sapphire substrate and followed by a development with deionized water to remove PEG moiety. The PS nanoporous network was facilely obtained, and the structural parameters could be effectively tuned by controlling the PS/PEG weight ratio of the spin-coating solution. 2-in. wafer-scale NPSSs were conveniently achieved through the PS nanoporous network in combination with traditional nanofabrication methods, such as O2 reactive ion etching (RIE), e-beam evaporation deposition, liftoff, and chlorine-based RIE. In order to investigate the performance of such NPSSs, typical blue LEDs with emission wavelengths of ~450 nm were grown on the NPSS and a flat sapphire substrate (FSS) by metal-organic chemical vapor deposition, respectively. The integral photoluminescence (PL) intensity of the NPSS LED was enhanced by 32.3 % compared to that of the FSS-LED. The low relative standard deviation of 4.7 % for PL mappings of NPSS LED indicated the high uniformity of PL data across the whole 2-in. wafer. Extremely simple, low cost, and high throughput of the process and the ability to fabricate at the wafer scale make PSL a potential method for production of nanopatterned sapphire substrates.

Influence of baking method and baking temperature on the optical properties of ZnO thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ng, Zi-Neng; Chan, Kah-Yoong

In this work, sol-gel spin coating technique was utilised to coat ZnO thin films on glass substrates. During the intermediate 3 minutes baking process, either hotplate or convection oven was employed to bake the samples. The temperature for the baking process was varied from 150°C to 300°C for both instruments. Avantes Optical Spectrophotometer was used to characterise the optical property. The optical transmittances of hotplate-baked and oven-baked samples showed different trends with increasing baking temperatures, ranging from below 50% transmittance to over 90% transmittance in the visible range of wavelength. The difference in baking mechanisms using hotplate and convection ovenmore » will be discussed in this paper.« less

Influence of baking method and baking temperature on the optical properties of ZnO thin films

NASA Astrophysics Data System (ADS)

Ng, Zi-Neng; Chan, Kah-Yoong

2015-04-01

In this work, sol-gel spin coating technique was utilised to coat ZnO thin films on glass substrates. During the intermediate 3 minutes baking process, either hotplate or convection oven was employed to bake the samples. The temperature for the baking process was varied from 150°C to 300°C for both instruments. Avantes Optical Spectrophotometer was used to characterise the optical property. The optical transmittances of hotplate-baked and oven-baked samples showed different trends with increasing baking temperatures, ranging from below 50% transmittance to over 90% transmittance in the visible range of wavelength. The difference in baking mechanisms using hotplate and convection oven will be discussed in this paper.

Influence of humidity on CO2 gas sensors based on polyetherimide polymer film

NASA Astrophysics Data System (ADS)

Kang, Ting; Xie, Guangzhong; Zhou, Yong; Xie, Tao; Tai, Huiling

2014-09-01

Quartz Crystal Microbalance (QCM) coated with polyetherimide (PEI) by spin coating method was applied for carbon dioxide (CO2) gas detection at room temperature in this study. The experiments were performed in dry and humid air atmospheres, and the results revealed that the prepared CO2 sensor in moisture circumstance exhibited a larger sensing response than that at dry condition. An enhanced sensing response took place for CO2 detection with the existence of water molecules. The effect of different humidity on QCM sensor performances was investigated as well in this paper. A curve, which displayed a proportional relationship between sensing response and water vapor concentration, was obtained. Moreover, the relevant sensing mechanisms were investigated.

Self-assembled biomimetic antireflection coatings

NASA Astrophysics Data System (ADS)

Linn, Nicholas C.; Sun, Chih-Hung; Jiang, Peng; Jiang, Bin

2007-09-01

The authors report a simple self-assembly technique for fabricating antireflection coatings that mimic antireflective moth eyes. Wafer-scale, nonclose-packed colloidal crystals with remarkable large hexagonal domains are created by a spin-coating technology. The resulting polymer-embedded colloidal crystals exhibit highly ordered surface modulation and can be used directly as templates to cast poly(dimethylsiloxane) (PDMS) molds. Moth-eye antireflection coatings with adjustable reflectivity can then be molded against the PDMS master. The specular reflection of replicated nipple arrays matches the theoretical prediction using a thin-film multilayer model. These biomimetic films may find important technological application in optical coatings and solar cells.

Actuation of digital micro drops by electrowetting on open microfluidic chips fabricated in photolithography.

PubMed

Ko, Hyojin; Lee, Jeong Soo; Jung, Chan-Hee; Choi, Jae-Hak; Kwon, Oh-Sun; Shin, Kwanwoo

2014-08-01

Basic manipulations of discrete liquid drops on opened microfluidic chips based on electrowetting on dielectrics were described. While most developed microfluidic chips are closed systems equipped with a top plate to cover mechanically and to contact electrically to drop samples, our chips are opened systems with a single plate without any electric contact to drops directly. The chips consist of a linear array of patterned electrodes at 1.8 mm pitch was fabricated on a glass plate coated with thin hydrophobic and dielectric layers by using various methods including photolithography, spin coating and ion sputtering. Several actuations such as lateral oscillation, colliding mergence and translational motion for 3-10 μL water drops have been demonstrated satisfactory. All these kinetic performances of opened chips were similar to those of closed chip systems, indicating superiority of a none-contact method for the transport of drops on opened microfluidic chips actuated by using electrowetting technique.

Frequency-Downconversion Stability of PMMA Coatings in Hybrid White Light-Emitting Diodes

NASA Astrophysics Data System (ADS)

Caruso, Fulvio; Mosca, Mauro; Rinella, Salvatore; Macaluso, Roberto; Calì, Claudio; Saiano, Filippo; Feltin, Eric

2016-01-01

We report on the properties of a poly(methyl methacrylate)-based coating used as a host for an organic dye in hybrid white light-emitting diodes. The device is composed by a pump source, which is a standard inorganic GaN/InGaN blue light-emitting diode (LED) emitting at around 450 nm, and a spin-coated conversion layer making use of Lumogen® F Yellow 083. Under prolonged irradiation, the coating exhibits significant bleaching, thus degrading the color rendering performance of the LED. We present experimental results that confirm that the local temperature rise of the operating diode does not affect the conversion layer. It is also proven that, during the test, the photostability of the organic dye is compromised, resulting in a chromatic shift from Commission Internationale de l'Eclairage (CIE) ( x; y) coordinates (0.30;0.39) towards the color of the pump (0.15;0.04). Besides photodegradation of the dye, we address a phenomenon attributed to modification of the polymer matrix activated by the LED's blue light energy as confirmed by ultraviolet-visible and Fourier-transform infrared spectroscopic analyses. Three methods for improving the overall stability of the organic coating are presented.

Spray- and spin-assisted layer-by-layer assembly of copper nanoparticles on thin-film composite reverse osmosis membrane for biofouling mitigation.

PubMed

Ma, Wen; Soroush, Adel; Van Anh Luong, Tran; Brennan, Gregory; Rahaman, Md Saifur; Asadishad, Bahareh; Tufenkji, Nathalie

2016-08-01

Copper nanoparticles (CuNPs) have long been considered as highly effective biocides; however, the lack of suitable methods for loading CuNPs onto polymeric membranes is recognized as being one of the primary reasons for the limited research concerning their application in membrane industries. A highly efficient spray- and spin-assisted layer-by-layer (SSLbL) method was developed to functionalize the TFC polyamide RO membranes with controllable loading of CuNPs for biofouling control. The SSLbL method was able to produce a uniform bilayer of polyethyleneimine-coated CuNPs and poly(acrylic) acid in less than 1 min, which is far more efficient than the traditional dipping approach (25-60 min). The successful loading of CuNPs onto the membrane surface was confirmed by XPS analysis. Increasing the number of bilayers from 2 to 10 led to an increased quantity of CuNPs on the membrane surface, from 1.75 to 23.7 μg cm(-2). Multi-layer coating exhibited minor impact on the membrane water permeation flux (13.3% reduction) while retaining the original salt rejection ability. Both static bacterial inactivation and cross-flow filtration tests demonstrated that CuNPs could significantly improve anti-biofouling property of a polyamide membrane and effectively inhibit the permeate flux reduction caused by bacterial deposition on the membrane surface. Once depleted, CuNPs can also be potentially regenerated on the membrane surface via the same SSLbL method. Copyright © 2016 Elsevier Ltd. All rights reserved.

Silica Nanoparticles Functionalized with Zwitterionic Sulfobetaine Siloxane for Application as a Versatile Antifouling Coating System.

PubMed

Knowles, Brianna R; Wagner, Pawel; Maclaughlin, Shane; Higgins, Michael J; Molino, Paul J

2017-06-07

The growing need to develop surfaces able to effectively resist biological fouling has resulted in the widespread investigation of nanomaterials with potential antifouling properties. However, the preparation of effective antifouling coatings is limited by the availability of reactive surface functional groups and our ability to carefully control and organize chemistries at a materials' interface. Here, we present two methods of preparing hydrophilic low-fouling surface coatings through reaction of silica-nanoparticle suspensions and predeposited silica-nanoparticle films with zwitterionic sulfobetaine (SB). Silica-nanoparticle suspensions were functionalized with SB across three pH conditions and deposited as thin films via a simple spin-coating process to generate hydrophilic antifouling coatings. In addition, coatings of predeposited silica nanoparticles were surface functionalized via exposure to zwitterionic solutions. Quartz crystal microgravimetry with dissipation monitoring was employed as a high throughput technique for monitoring and optimizing reaction to the silica-nanoparticle surfaces. Functionalization of nanoparticle films was rapid and could be achieved over a wide pH range and at low zwitterion concentrations. All functionalized particle surfaces presented a high degree of wettability and resulted in large reductions in adsorption of bovine serum albumin protein. Particle coatings also showed a reduction in adhesion of fungal spores (Epicoccum nigrum) and bacteria (Escherichia coli) by up to 87 and 96%, respectively. These results indicate the potential for functionalized nanosilicas to be further developed as versatile fouling-resistant coatings for widespread coating applications.

Surface analytical characterization of Streptavidin/poly(3-hexylthiophene) bilayers for bio-electronic applications

NASA Astrophysics Data System (ADS)

Sportelli, M. C.; Picca, R. A.; Manoli, K.; Re, M.; Pesce, E.; Tapfer, L.; Di Franco, C.; Cioffi, N.; Torsi, L.

2017-10-01

The analytical performance of bioelectronic devices is highly influenced by their fabrication methods. In particular, the final architecture of field-effect transistor biosensors combining spin-cast poly(3-hexylthiophene) (P3HT) film and a biomolecule interlayer deposited on a SiO2/Si substrate can lead to the development of highly performing sensing systems, such as for the case of streptavidin (SA) used for biotin sensing. To gain a better understanding of the quality of the interfacial area, critical is the assessment of the morphological features characteristic of the adopted biolayer deposition protocol, namely: the layer-by-layer (LbL) approach and the spin coating technique. The present study relies on a combined surface spectroscopic and morphological characterization. Specifically, X-ray photoelectron spectroscopy operated in the parallel angle-resolved mode allowed the non-destructive investigation of the in-depth chemical composition of the SA film, alone or in the presence of the P3HT overlayer. Spectroscopic data were supported and corroborated by the results obtained with a Scanning Electron and a Helium Ion microscope investigation performed on the SA layer that provided relevant information on the protein structural arrangement or on its surface morphology. Clear differences emerged between the SA layers prepared by the two approaches, with the layer-by-layer deposition resulting in a smoother and better defined bio-electronic interface. Such findings support the superior analytical performance shown by bioelectronic devices based on LbL-deposited protein layers over spin coated ones.

Physics of Spin-Polarized Media

DTIC Science & Technology

2007-11-21

midsection of the cell serving as the cathode, and liquid molten salt outside the cell serving as the anode [5]. This new method is very promising for of...filling atomic clock and magnetometer cells by electrolysis through the glass walls; (6) new investigations of optical pumping and magnetic resonances...cesium vapor can be used to polarize 3 Cs nuclei in CsH salt that coats the walls of a vapor cell. This result, an important first step, has been

Fabrication of nanostructured Al-doped ZnO thin film for methane sensing applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shafura, A. K., E-mail: shafura@ymail.com; Azhar, N. E. I.; Uzer, M.

2016-07-06

CH{sub 4} gas sensor was fabricated using spin-coating method of the nanostructured ZnO thin film. Effect of annealing temperature on the electrical and structural properties of the film was investigated. Dense nanostructured ZnO film are obtained at higher annealing temperature. The optimal condition of annealing temperature is 500°C which has conductivity and sensitivity value of 3.3 × 10{sup −3} S/cm and 11.5%, respectively.

Oxygen Plasma Effect on QCM Sensor Coated Polystyrene Film

NASA Astrophysics Data System (ADS)

Khusnah, N. F.; Sakti, S. P.; Santjojo, D. J. D. H.

2018-05-01

Hydrophobicity property of polystyrene (PS) thin film is one of the essential factors to be considered in the development of quartz crystal microbalance (QCM) biosensor using polystyrene as matrix layer. Many methods were developed to improve the immobilization rate of the biomolecule on the sensor surface without affecting the QCM essential works. Surface modification of the sensor surface aims to modify the physical and or chemical property of the surface. A straightforward method, the fast, environmentally-friendly, and low-cost solution to modify the sensor surface coated with polystyrene film is using oxygen plasma. In this experiment, the polystyrene film was spin-coated on both surface of QCM electrodes and then heated at 100 °C. The specimen is then placed for 5 min long in a chamber filled with oxygen plasma generated by 2 MHz RF-DC high-density plasma system. The relationship between DC-bias used and the changes in morphology properties of the coated film was characterized by Topography Measurement System (TMS) and Contact Angle Measurement. The electrical characteristic of QCM was also characterized using Impedance Analyzer. It was revealed that the contact angle of oxygen plasma treated film is changed and depicted the hydrophobic character. Also, there is an increasing resonance frequency of the sensor after oxygen plasma treatment indicates an etching mechanism occurs during plasma treatment.

Clean thermal decomposition of tertiary-alkyl metal thiolates to metal sulfides: environmentally-benign, non-polar inks for solution-processed chalcopyrite solar cells.

PubMed

Heo, Jungwoo; Kim, Gi-Hwan; Jeong, Jaeki; Yoon, Yung Jin; Seo, Jung Hwa; Walker, Bright; Kim, Jin Young

2016-11-09

We report the preparation of Cu 2 S, In 2 S 3 , CuInS 2 and Cu(In,Ga)S 2 semiconducting films via the spin coating and annealing of soluble tertiary-alkyl thiolate complexes. The thiolate compounds are readily prepared via the reaction of metal bases and tertiary-alkyl thiols. The thiolate complexes are soluble in common organic solvents and can be solution processed by spin coating to yield thin films. Upon thermal annealing in the range of 200-400 °C, the tertiary-alkyl thiolates decompose cleanly to yield volatile dialkyl sulfides and metal sulfide films which are free of organic residue. Analysis of the reaction byproducts strongly suggests that the decomposition proceeds via an SN 1 mechanism. The composition of the films can be controlled by adjusting the amount of each metal thiolate used in the precursor solution yielding bandgaps in the range of 1.2 to 3.3 eV. The films form functioning p-n junctions when deposited in contact with CdS films prepared by the same method. Functioning solar cells are observed when such p-n junctions are prepared on transparent conducting substrates and finished by depositing electrodes with appropriate work functions. This method enables the fabrication of metal chalcogenide films on a large scale via a simple and chemically clear process.

Clean thermal decomposition of tertiary-alkyl metal thiolates to metal sulfides: environmentally-benign, non-polar inks for solution-processed chalcopyrite solar cells

NASA Astrophysics Data System (ADS)

Heo, Jungwoo; Kim, Gi-Hwan; Jeong, Jaeki; Yoon, Yung Jin; Seo, Jung Hwa; Walker, Bright; Kim, Jin Young

2016-11-01

We report the preparation of Cu2S, In2S3, CuInS2 and Cu(In,Ga)S2 semiconducting films via the spin coating and annealing of soluble tertiary-alkyl thiolate complexes. The thiolate compounds are readily prepared via the reaction of metal bases and tertiary-alkyl thiols. The thiolate complexes are soluble in common organic solvents and can be solution processed by spin coating to yield thin films. Upon thermal annealing in the range of 200-400 °C, the tertiary-alkyl thiolates decompose cleanly to yield volatile dialkyl sulfides and metal sulfide films which are free of organic residue. Analysis of the reaction byproducts strongly suggests that the decomposition proceeds via an SN1 mechanism. The composition of the films can be controlled by adjusting the amount of each metal thiolate used in the precursor solution yielding bandgaps in the range of 1.2 to 3.3 eV. The films form functioning p-n junctions when deposited in contact with CdS films prepared by the same method. Functioning solar cells are observed when such p-n junctions are prepared on transparent conducting substrates and finished by depositing electrodes with appropriate work functions. This method enables the fabrication of metal chalcogenide films on a large scale via a simple and chemically clear process.

Neat monolayer tiling of molecularly thin two-dimensional materials in 1 min

PubMed Central

Matsuba, Kazuaki; Wang, Chengxiang; Saruwatari, Kazuko; Uesusuki, Yusuke; Akatsuka, Kosho; Osada, Minoru; Ebina, Yasuo; Ma, Renzhi; Sasaki, Takayoshi

2017-01-01

Controlled arrangement of molecularly thin two-dimensional (2D) materials on a substrate, particularly into precisely organized mono- and multilayer structures, is a key to design a nanodevice using their unique and enhanced physical properties. Several techniques such as mechanical transfer process and Langmuir-Blodgett deposition have been applied for this purpose, but they have severe restrictions for large-scale practical applications, for example, limited processable area and long fabrication time, requiring skilled multistep operations. We report a facile one-pot spin-coating method to realize dense monolayer tiling of various 2D materials, such as graphene and metal oxide nanosheets, within 1 min over a wide area (for example, a 30-mmφ substrate). Centrifugal force drives the nanosheets in a thin fluid layer to the substrate edge where they are packed edge to edge all the way to the central region, without forming overlaps. We investigated the relationship between precursor concentration, rotation speed, and ultraviolet-visible absorbance and developed an effective method to optimize the parameters for neat monolayer films. The multilayer buildup is feasible by repeating the spin-coating process combined with a heat treatment at moderate temperature. This versatile solution-based technique will provide both fundamental and practical advancements in the rapid large-scale production of artificial lattice-like films and nanodevices based on 2D materials. PMID:28695198

Solution-assisted ultrafast transfer of graphene-based thin films for solar cells and humidity sensors.

PubMed

Sun, Jiawei; Xie, Xiao; Bi, Hengchang; Jia, Haiyang; Zhu, Chongyang; Wan, Neng; Huang, Jianqiu; Nie, Meng; Li, Dan; Sun, Litao

2017-03-01

Vacuum filtration enables the fabrication of large-area graphene-based membranes (GBMs), possessing a smoother surface than that by spray, spin coating or drop casting. However, due to the strong interaction with substrates, the separation of thin GBMs from the filter is problematic. Conventional stamping separation/transfer of graphene oxide (GO) thin films requires another substrate and pressing for >10 h, which may damage the delicate structure of the transfer substrates. Other methods require GO to be reduced on filters before separation, thus limiting the reduction methods. Inspired by a coagulation bath that enables rapid formation of ultrastrong GO fibers, we present an ultrafast (<1 min) and solution-assisted strategy to fabricate smooth and freestanding GO films. The diverse interfacial energy of hydrogen bonds also demonstrates another reason for the successful separation. The film thickness ranges from 45 nm to several micrometers. When used as a composite of counter electrodes in dye sensitized solar cells, it showed higher (8.58%) power conversion efficiency than its spin-(7.71%) and spray-coated (8.07%) counterparts. It also showed promising performance in capacitive humidity sensors. The capacitance varied by three orders of magnitude in the range of the relative humidity of 15%-95%. Therefore the strategy realizes an ultrafast and high-quality film production which is suitable for various applications.

Solution-assisted ultrafast transfer of graphene-based thin films for solar cells and humidity sensors

NASA Astrophysics Data System (ADS)

Sun, Jiawei; Xie, Xiao; Bi, Hengchang; Jia, Haiyang; Zhu, Chongyang; Wan, Neng; Huang, Jianqiu; Nie, Meng; Li, Dan; Sun, Litao

2017-03-01

Vacuum filtration enables the fabrication of large-area graphene-based membranes (GBMs), possessing a smoother surface than that by spray, spin coating or drop casting. However, due to the strong interaction with substrates, the separation of thin GBMs from the filter is problematic. Conventional stamping separation/transfer of graphene oxide (GO) thin films requires another substrate and pressing for >10 h, which may damage the delicate structure of the transfer substrates. Other methods require GO to be reduced on filters before separation, thus limiting the reduction methods. Inspired by a coagulation bath that enables rapid formation of ultrastrong GO fibers, we present an ultrafast (<1 min) and solution-assisted strategy to fabricate smooth and freestanding GO films. The diverse interfacial energy of hydrogen bonds also demonstrates another reason for the successful separation. The film thickness ranges from 45 nm to several micrometers. When used as a composite of counter electrodes in dye sensitized solar cells, it showed higher (8.58%) power conversion efficiency than its spin-(7.71%) and spray-coated (8.07%) counterparts. It also showed promising performance in capacitive humidity sensors. The capacitance varied by three orders of magnitude in the range of the relative humidity of 15%-95%. Therefore the strategy realizes an ultrafast and high-quality film production which is suitable for various applications.

A novel surface modification approach for protein and cell microarrays

NASA Astrophysics Data System (ADS)

Kurkuri, Mahaveer D.; Driever, Chantelle; Thissen, Helmut W.; Voelcker, Nicholas H.

2007-01-01

Tissue engineering and stem cell technologies have led to a rapidly increasing interest in the control of the behavior of mammalian cells growing on tissue culture substrates. Multifunctional polymer coatings can assist research in this area in many ways, for example, by providing low non-specific protein adsorption properties and reactive functional groups at the surface. The latter can be used for immobilization of specific biological factors that influence cell behavior. In this study, glass slides were coated with copolymers of glycidyl methacrylate (GMA) and poly(ethylene glycol) methacrylate (PEGMA). The coatings were prepared by three different methods based on dip and spin coating as well as polymer grafting procedures. Coatings were characterized by X-ray photoelectron spectroscopy, surface sensitive infrared spectroscopy, ellipsometry and contact angle measurements. A fluorescently labelled protein was deposited onto reactive coatings using a contact microarrayer. Printing of a model protein (fluorescein labeled bovine serum albumin) was performed at different protein concentrations, pH, temperature, humidity and using different micropins. The arraying of proteins was studied with a microarray scanner. Arrays printed at a protein concentration above 50 μg/mL prepared in pH 5 phosphate buffer at 10°C and 65% relative humidity gave the most favourable results in terms of the homogeneity of the printed spots and the fluorescence intensity.

Aging effects of the precursor solutions on the properties of spin coated Ga-doped ZnO thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Serrao, Felcy Jyothi, E-mail: jyothiserrao@gmail.com; Dharmaprakash, S. M.

2015-06-24

In this study, gallium doped zinc oxide thin films (GZO) were grown on a glass substrate by a simple sol-gel process and spin coating technique using zinc acetate and gallium nitrate (3at%) as precursors for Zn and Ga ions respectively. The effects of aging time of the precursor solution on the structural and optical properties of the GZO films were investigated. The surface morphology, grain size, film thickness and optical properties of the GZO films were found to depend directly on the sol aging time. XRD studies reveal that the films are polycrystalline with a hexagonal wurtzite structure and showmore » the c-axis grain orientation. Optical transmittance spectra of all the films exhibited transmittance higher than about 82% within the visible wavelength region. A sharp fundamental absorption edge with a slight blue shifting was observed with an increase in sol aging time which can be explained by Burstein-Moss effect. The result indicates that an appropriate aging time of the sol is important for the improvement of the structural and optical properties of GZO thin films derived from sol-gel method.« less

Interparticle spacing and structural ordering in superlattice PbS nanocrystal solids undergoing ligand exchange

DOE PAGES

Weidman, Mark C.; Yager, Kevin G.; Tisdale, William A.

2014-12-12

Controlling the interparticle spacing in quantum dot (QD) thin films is the most readily accessible way to control transport rates between neighboring QDs and a critical component of device optimization. Here, we use X-ray scattering measurements to accurately measure the interparticle spacing in films of highly monodisperse lead sulfide (PbS) QDs that have undergone a variety of device-relevant ligand exchanges. We tabulate these values for use in simulations and data analysis. We find that monothiol and dithiol ligand species typically result in interparticle spacing values that are equal to the length of a single monothiol or dithiol ligand. Additionally, wemore » find that spin-coating a thick film of QDs followed by a long-duration ligand exchange results in a more complete ligand exchange than spin-coating many thin layers with short-duration ligand exchanges in between. The former method also preserves a remarkable degree of the long-range ordering that was present in the film prior to ligand exchange. These results shed light on ways to produce highly-ordered QD solids with compact and functional ligands, which could lead to enhanced interdot coupling and transport phenomena.« less

Achieving polydimethylsiloxane/carbon nanotube (PDMS/CNT) composites with extremely low dielectric loss and adjustable dielectric constant by sandwich structure

NASA Astrophysics Data System (ADS)

Fan, Benhui; Liu, Yu; He, Delong; Bai, Jinbo

2018-01-01

Sandwich-structured composites of polydimethylsiloxane/carbon nanotube (PDMS/CNT) bulk between two neat PDMS thin films with different thicknesses are prepared by the spin-coating method. Taking advantage of CNT's percolation behavior, the composite keeps relatively high dielectric constant (ɛ' = 40) at a low frequency (at 100 Hz). Meanwhile, due to the existence of PDMS isolated out-layers which limits the conductivity of the composite, the composite maintains an extremely low dielectric loss (tan δ = 0.01) (at 100 Hz). Moreover, the same matrix of the out-layer and bulk can achieve excellent interfacial adhesion, and the thickness of the coating layer can be controlled by a multi-cycle way. Then, based on the experimental results, the calculation combining the percolation theory and core-shell model is used to analyze the thickness effect of the coating layer on ɛ'. The obtained relationship between the ɛ' of the composite and the thickness of the coating layer can help to optimize the sandwich structure in order to obtain the adjustable ɛ' and the extremely low tan δ.

Spin dependent transport and spin transfer in nanoconstrictions and current confined nanomagnets

NASA Astrophysics Data System (ADS)

Ozatay, Ozhan

In this thesis, I have employed point contact spectroscopy to determine the nature of electron transport across constrained domain walls in a ferromagnetic nanocontact and to uncover the relationship between ballisticity of electron transport and domain wall magnetoresistance. In the range of hole sizes studied (from 10 to 3 nm) the resulting magnetoresistance was found to be less than 0.5% and one that increases with decreasing contact size. I have used point contacts as local probes, to study the spin dependent transport across Ferromagnet/Normal Metal/Ferromagnet(FM/NM/FM) trilayers as well as the consequences of localized spin polarized current injection into a nano magnet on spin angular momentum transfer and high frequency magnetization dynamics. I have demonstrated that absolute values for spin transfer switching critical currents are reduced in this new geometry as compared to uniform current injection. I have also performed micromagnetic simulations to determine the evolution of magnetization under the application of magnetic fields and currents to gain more insights into experimental results. I have used Scanning Transmission Electron Microscopy (STEM), X-Ray Photoemission Spectroscopy (XPS) and Electron Energy Loss Spectroscopy (EELS) techniques to characterize the interfacial mixing and oxygen diffusion in the metallic multilayers of interest. I have shown that the Ta/CuOx bilayer structure provides a smooth substrate by improving interfacial roughness due to grain boundary diffusion of oxygen and reaction with Ta that fills in the grain boundary gaps in Cu. Analysis of the Py/AlOx interface proved a strong oxidation passivation on the Py surface by Al coating accompanied by Fe segregation into the alumina. I have utilized the characterization results to design a new nanomagnet whose sidewalls are protected from adventitious sidewall oxide layers and yields improved device performance. The oxide layers that naturally develop at the sidewalls of Py nanomagnets cause an enhancement in magnetic damping especially for temperatures below the blocking temperature of the AFM layer (≤40K). Studies with pillars protected by Al coating and ones with more NiO coating (˜2.5 nm) shed light onto the role of surface oxides in determining temperature dependent behaviour of both spin torque and field driven switching characteristics.

The influence of the quantum dot/polymethylmethacrylate composite preparation method on the stability of its optical properties under laser radiation

NASA Astrophysics Data System (ADS)

Zvaigzne, M. A.; Martynov, I. L.; Krivenkov, V. A.; Samokhvalov, P. S.; Nabiev, I. R.

2017-01-01

Photoluminescent semiconductor nanocrystals, quantum dots (QDs), are nowadays one of the most promising materials for developing a new generation of fluorescent labels, new types of light-emitting devices and displays, flexible electronic components, and solar panels. In many areas the use of QDs is associated with an intense optical excitation, which, in the case of a prolonged exposure, often leads to changes in their optical characteristics. In the present work we examined how the method of preparation of quantum dot/polymethylmethacrylate (QD/PMMA) composite influenced the stability of the optical properties of QD inside the polymer matrix under irradiation by different laser harmonics in the UV (355 nm) and visible (532 nm) spectral regions. The composites were synthesized by spin-coating and radical polymerization methods. Experiments with the samples obtained by spin-coating showed that the properties of the QD/PMMA films remain almost constant at values of the radiation dose below 10 fJ per particle. Irradiating the composites prepared by the radical polymerization method, we observed a monotonic increase in the luminescence quantum yield (QY) accompanied by an increase in the luminescence decay time regardless of the wavelength of the incident radiation. We assume that the observed difference in the optical properties of the samples under exposure to laser radiation is associated with the processes occurring during radical polymerization, in particular, with charge transfer from the radical particles inside QDs. The results of this study are important for understanding photophysical properties of composites on the basis of QDs, as well as for selection of the type of polymer and the composite synthesis method with quantum dots that would allow one to avoid the degradation of their luminescence.

Patterned forests of vertically-aligned multiwalled carbon nanotubes using metal salt catalyst solutions.

PubMed

Garrett, David J; Flavel, Benjamin S; Baronian, Keith H R; Downard, Alison J

2013-01-01

A simple method for producing patterned forests of multiwalled carbon nanotubes (MWCNTs) is described. An aqueous metal salt solution is spin-coated onto a substrate patterned with photoresist by standard methods. The photoresist is removed by acetone washing leaving the acetone-insoluble catalyst pattern on the substrate. Dense forests of vertically aligned (VA) MWCNTs are grown on the patterned catalyst layers by chemical vapour deposition. The procedures have been demonstrated by growing MWCNT forests on two substrates: silicon and conducting graphitic carbon films. The forests adhere strongly to the substrates and when grown directly on carbon film, offer a simple method of preparing MWCNT electrodes.

Solvent effect on polystyrene surface roughness on top of QCM sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakti, Setyawan P., E-mail: sakti@ub.ac.id; Rahmawati, Eka; Robiandi, Fadli

2016-03-11

Quartz Crystal Microbalance (QCM) has been used as a basis for many chemical sensors and biosensor. Its sensitivity to mass change which can detect a mass change on its surface down to sub ng/cm2 is one of its interesting aspects. Another interesting feature is its ability to work in liquid environment. However, there are many aspects which influence QCM sensor properties in contact with liquid. One of the aspects is surface roughness of the matrix layer where on top of it a biological sensitive layer will be immobilized. One of matrix layers in the immobilizing biological sensitive layer was polystyrene.more » Polystyrene was coated on the QCM sensor by using the spin coating method. During the coating process, polystyrene was solved using non-polar solvent. It is known that the physical and chemical properties of the solvent affect a transition process from soluble polymer becoming rigid polymer layer. In this work, we show that polystyrene solved in chloroform has a higher surface roughness compare to one solved in toluene, xylene, or tetrahydrofuran. Surface roughness of the polystyrene coating were measured using a non-contact profilometer. However, we also found that there is no difference on the electrical impedance of the QCM sensor coated with polystyrene resulted from differing solvent when the sensor was in contact with air and water. Thus, all of the mentioned solvent can be used to solve the polystyrene as a coating material for QCM sensor without affecting the electrical performance of the sensor, but the choice of the solution can be used as a simple method to control the difference roughness of the polystyrene coating.« less

Solvent effect on polystyrene surface roughness on top of QCM sensor

NASA Astrophysics Data System (ADS)

Sakti, Setyawan P.; Rahmawati, Eka; Robiandi, Fadli

2016-03-01

Quartz Crystal Microbalance (QCM) has been used as a basis for many chemical sensors and biosensor. Its sensitivity to mass change which can detect a mass change on its surface down to sub ng/cm2 is one of its interesting aspects. Another interesting feature is its ability to work in liquid environment. However, there are many aspects which influence QCM sensor properties in contact with liquid. One of the aspects is surface roughness of the matrix layer where on top of it a biological sensitive layer will be immobilized. One of matrix layers in the immobilizing biological sensitive layer was polystyrene. Polystyrene was coated on the QCM sensor by using the spin coating method. During the coating process, polystyrene was solved using non-polar solvent. It is known that the physical and chemical properties of the solvent affect a transition process from soluble polymer becoming rigid polymer layer. In this work, we show that polystyrene solved in chloroform has a higher surface roughness compare to one solved in toluene, xylene, or tetrahydrofuran. Surface roughness of the polystyrene coating were measured using a non-contact profilometer. However, we also found that there is no difference on the electrical impedance of the QCM sensor coated with polystyrene resulted from differing solvent when the sensor was in contact with air and water. Thus, all of the mentioned solvent can be used to solve the polystyrene as a coating material for QCM sensor without affecting the electrical performance of the sensor, but the choice of the solution can be used as a simple method to control the difference roughness of the polystyrene coating.

Bioactivity of CaSiO3/poly-lactic acid (PLA) composites prepared by various surface loading methods of CaSiO3 powder.

PubMed

Okada, Kiyoshi; Hasegawa, Fumikazu; Kameshima, Yoshikazu; Nakajima, Akira

2007-05-01

Mixing bioactive ceramic powders with polymers is an effective method for generating bioactivity to the polymer-matrix composites but it is necessary to incorporate up to 40 vol% of bioactive ceramic powder. However, such a high mixing ratio offsets the advantages of the flexibility and formability of polymer matrix and it would be highly advantageous to lower the mixing ratio. Since surface loading of ceramic powders in the polymer is thought to be an effective way of reducing the mixing ratio of the ceramic powder while maintaining bioactive activity, CaSiO(3)/poly-lactic acid (PLA) composites were prepared by three methods; (1) casting, (2) spin coating and (3) hot pressing. In methods (1) and (2), a suspension was prepared by dissolving PLA in chloroform and dispersing CaSiO(3) powder in it. The suspension was cast and dried to form a film in the case of method (1) while it was spin-coated on a PLA substrate in method (2). In method (3), CaSiO(3) powder was surface loaded on to a PLA substrate by hot pressing. The bioactivity of these samples was investigated in vitro using simulated body fluid (SBF). Apatite formation was not observed in the samples prepared by method (1) but some apatite formation was achieved by mixing polyethylene glycol (PEG) with the PLA, producing a porous polymer matrix. In method (2), apatite was clearly observed after soaking for 7 days. Enhanced apatite formation was observed in method (3), the thickness of the resulting apatite layers becoming about 20 microm after soaking for 14 days. Since the amount of CaSiO(3) powder used in these samples was only

Bioactivity of CaSiO3/poly-lactic acid (PLA) composites prepared by various surface loading methods of CaSiO3 powder.

PubMed

Okada, Kiyoshi; Hasegawa, Fumikazu; Kameshima, Yoshikazu; Nakajima, Akira

2007-08-01

Mixing bioactive ceramic powders with polymers is an effective method for generating bioactivity to the polymer-matrix composites but it is necessary to incorporate up to 40 vol% of bioactive ceramic powder. However, such a high mixing ratio offsets the advantages of the flexibility and formability of polymer matrix and it would be highly advantageous to lower the mixing ratio. Since surface loading of ceramic powders in the polymer is thought to be an effective way of reducing the mixing ratio of the ceramic powder while maintaining bioactive activity, CaSiO(3)/poly-lactic acid (PLA) composites were prepared by three methods; (1) casting, (2) spin coating and (3) hot pressing. In methods (1) and (2), a suspension was prepared by dissolving PLA in chloroform and dispersing CaSiO(3) powder in it. The suspension was cast and dried to form a film in the case of method (1) while it was spin-coated on a PLA substrate in method (2). In method (3), CaSiO(3) powder was surface loaded on to a PLA substrate by hot-pressing. The bioactivity of these samples was investigated in vitro using simulated body fluid (SBF). Apatite formation was not observed in the samples prepared by method (1) but some apatite formation was achieved by mixing polyethylene glycol (PEG) with the PLA, producing a porous polymer matrix. In method (2), apatite was clearly observed after soaking for 7 days. Enhanced apatite formation was observed in method (3), the thickness of the resulting apatite layers becoming about 20 microm after soaking for 14 days. Since the amount of CaSiO(3) powder used in these samples was only < or =0.4 vol%, it is concluded that this preparation method is very effective in generating bioactivity in polymer-matrix composites by loading with only very small amounts of ceramic powder.

Luminescence properties of Lu2O3: Tb film prepared by Pechini sol-gel method

NASA Astrophysics Data System (ADS)

Shen, Siqing; Wang, Jian; Xu, Zhibin; Xie, Jianjun; Shi, Ying

2010-10-01

Uniform and crack free Tb3+ doped lutetium oxide (Lu2O3:Tb) films were prepared by Pechini sol-gel method combined with the spin-coating technique. The influence of the different substrate (monocrystalline silicon (111) and silica glass) and atmosphere (N2 and Air) on the luminescence properties of films was investigated. According to the emission spectra, we found that the luminous intensity was higher on silica glass substrate. Moreover, it was found that the luminous intensity calcined in N2 was higher almost twice as that calcined in air.

Luminescence properties of Lu2O3: Tb film prepared by Pechini sol-gel method

NASA Astrophysics Data System (ADS)

Shen, Siqing; Wang, Jian; Xu, Zhibin; Xie, Jianjun; Shi, Ying

2011-02-01

Uniform and crack free Tb3+ doped lutetium oxide (Lu2O3:Tb) films were prepared by Pechini sol-gel method combined with the spin-coating technique. The influence of the different substrate (monocrystalline silicon (111) and silica glass) and atmosphere (N2 and Air) on the luminescence properties of films was investigated. According to the emission spectra, we found that the luminous intensity was higher on silica glass substrate. Moreover, it was found that the luminous intensity calcined in N2 was higher almost twice as that calcined in air.

Fabrication and Characterization of Polyvinylidene Fluoride Microfilms for Microfluidic Applications

NASA Astrophysics Data System (ADS)

Rao, Yammani Venkat Subba; Raghavan, Aravinda Narayanan; Viswanathan, Meenakshi

2016-10-01

The ability to create patterns of piezo responsive material on smooth substrate is an important method to develop efficient microfluidic mixers. This paper reports the fabrication of Poly vinylidene fluoride microfilms using spin-coating on smooth glass surface. The suitable crystalline phases, surface morphology and microstructural properties of the PVDF films have been investigated. We found that films of average thickness 10μm, had average roughness of 0.13μm. These PVDF films are useful in microfluidic mixer applications.

Metal Organic Chemical Vapor Deposition of Oxide Films for Advanced Applications

DTIC Science & Technology

2000-06-01

coatings , photovoltaics, touch sensitive controls, electromagnetic shielding (as found on microwave ovens and stealth fighters), static dissipaters, and so...depositing high quality films. The methods are physical vapor deposition ( PVD ), spin/mist deposition, (CVD), and alternating layer (AL) CVD. PVD ...PZT & SBT, YBa2Cu3O, CeO, InO, TCOs, Varistors Ta2O5 , ZrO, MnO, HfO, CeO, MnO, MgO SAW/microwave Silicon/: Si, SiGe, SiGeC, �. Opto-electronics

Early Intervention Stem Cell-Based Therapy (EISCBT) for Corneal Burns and Trauma

DTIC Science & Technology

2016-10-01

formation through material chemistry, topography, and mechanical properties (Clark et al., 1991; Engler et al., 2006; LeGeros, 2008). During development...methods ( Sun et al., 2015). Glass wafers were cleaned with 70% ethanol spin, coated with a 5 µm thick layer of SPR220.3 photoresist (MicroChem Corp...which point a tissue sheet could be mechanically separated from the substrate. Select tissue sheets were stained with Vybrant DiI ((2Z)-2-[(E)-3-(3,3

Effect of ph Value and Calcination Temperature on Structure and Magnetic Properties of Strontium Hexaferrite Thin Film

NASA Astrophysics Data System (ADS)

Shanaghi, A.

2012-02-01

Strontium hexaferrite was widely used in the fabrication of commercial permanent magnets and certain microwave devices. In this study, the strontium hexaferrite nanoparticle coatings were prepared by sol-gel method and using spin coating process on silicon substrate, then the effect of pH value, such as 5, 7 and 9, and calcination temperatures, such as 600°C, 800°C, and 1000°C, on structural and magnetic properties of strontium hexaferrite thin films were investigated by XRD, SEM and VSM measurements. The maximum saturation magnetization value of 57.43 emu/g and coercivity value of 3908 Oe were achieved for the thin film with crystallite size approximately 41 nm, prepared at pH value of 7 and calcinations temperature of 800°C.

Role of annealing duration on the microstructure and electrochemical performance of β-V2O5 thin films

NASA Astrophysics Data System (ADS)

Jeyalakshmi, K.; Muralidharan, G.

2014-03-01

Vanadium pentoxide thin films have been prepared by sol-gel spin coating method. The eight-layered films coated on fluorine-doped tin oxide substrate and glass substrate were subjected to different durations of annealing under a constant annealing temperature of 300 °C from 30 to 120 min. The X-ray diffraction spectrum reveals crystallinity along (2 0 0) direction. The SEM images of these films show the variation in the surface morphology with increase in annealing duration. The supercapacitor behaviour has been studied using cyclic voltammetry technique and electrochemical impedance spectroscopy. The film annealed for 60 min exhibits a maximum specific capacitance of 346 F/g at a scan rate of 5 mV/s with a charge transfer resistance of 172 Ω.

The role of annealing temperature variation on ZnO nanorods array deposited on TiO2 seed layer

NASA Astrophysics Data System (ADS)

Asib, N. A. M.; Aadila, A.; Afaah, A. N.; Rusop, M.; Khusaimi, Z.

2018-05-01

Seed layer of Titanium dioxide (TiO2) by sol-gel spin coating technique were coated on glass substrate to grow Zinc oxide nanorods (ZNR) by solution-immersion method. The fabricated ZNR were annealed at various temperatures ranged from 400 to 600° C. FESEM images revealed that smaller ZNR were densely grown at optimum temperature of 450 and 500°C. Meanwhile, for all samples a dominant (0 0 2) diffraction peak of ZNR recorded by XRD patterns was at 34.4° which corresponding to hexagonal ZNR with a wurtzite structure. UV-Vis absorbance spectra showed the maximum absorption properties at UV region were detected at 450 and 500°C. The samples also showed high absorbance values at visible region.

Zirconia-based mixed potential sensor with Pt electrode prepared by spin-coating of polymeric precursor

NASA Astrophysics Data System (ADS)

Chrzan, A.; Woźniak, Ł.; Szymczewska, D.; Jasiński, P.

2016-11-01

Many types of yttria-stabilized zirconia (YSZ) based gas sensors have been explored extensively in recent years. Great attention have been directed to mixed-potential-type gas sensors. It is due to growing concerns with environmental issues. Not without a significance is the fact of very attractive performance of this type of sensor allowing to detect low concentration of pollutant gases. In this paper two types of YSZ based mixed-potential planar sensors were investigated, with platinum electrode painted using commercial paste and with spin coated platinum layer. Both types had second electrode in the form of porous gold. Measurements were performed at 400 °C in synthetic air and different concentrations of SO2. Gas flow was set to 100 cm3min-1 and the concentration of 50 ppm SO2 was tested. During this measurements the sensor was sintered in-situ at increasing temperatures. Sensor with 100 nm spin-coated platinum layer sintered at 700 °C was shown to exhibit two times smaller response than sensor with 5 μm porous electrode, while consisting of over 20 times smaller amount of Pt. The influence of sintering temperature on electrical conductivity of platinum films was also examined. Moreover, the platinum microstructure was investigated using SEM microscopy.

Nonvolatile memory thin film transistors using CdSe/ZnS quantum dot-poly(methyl methacrylate) composite layer formed by a two-step spin coating technique

NASA Astrophysics Data System (ADS)

Chen, Ying-Chih; Huang, Chun-Yuan; Yu, Hsin-Chieh; Su, Yan-Kuin

2012-08-01

The nonvolatile memory thin film transistors (TFTs) using a core/shell CdSe/ZnS quantum dot (QD)-poly(methyl methacrylate) (PMMA) composite layer as the floating gate have been demonstrated, with the device configuration of n+-Si gate/SiO2 insulator/QD-PMMA composite layer/pentacene channel/Au source-drain being proposed. To achieve the QD-PMMA composite layer, a two-step spin coating technique was used to successively deposit QD-PMMA composite and PMMA on the insulator. After the processes, the variation of crystal quality and surface morphology of the subsequent pentacene films characterized by x-ray diffraction spectra and atomic force microscopy was correlated to the two-step spin coating. The crystalline size of pentacene was improved from 147.9 to 165.2 Å, while the degree of structural disorder was decreased from 4.5% to 3.1% after the adoption of this technique. In pentacene-based TFTs, the improvement of the performance was also significant, besides the appearances of strong memory characteristics. The memory behaviors were attributed to the charge storage/discharge effect in QD-PMMA composite layer. Under the programming and erasing operations, programmable memory devices with the memory window (Δ Vth) = 23 V and long retention time were obtained.

Fabrication of a Flexible Amperometric Glucose Sensor Using Additive Processes

PubMed Central

Du, Xiaosong; Durgan, Christopher J.; Matthews, David J.; Motley, Joshua R.; Tan, Xuebin; Pholsena, Kovit; Árnadóttir, Líney; Castle, Jessica R.; Jacobs, Peter G.; Cargill, Robert S.; Ward, W. Kenneth; Conley, John F.; Herman, Gregory S.

2015-01-01

This study details the use of printing and other additive processes to fabricate a novel amperometric glucose sensor. The sensor was fabricated using a Au coated 12.7 μm thick polyimide substrate as a starting material, where micro-contact printing, electrochemical plating, chloridization, electrohydrodynamic jet (e-jet) printing, and spin coating were used to pattern, deposit, chloridize, print, and coat functional materials, respectively. We have found that e-jet printing was effective for the deposition and patterning of glucose oxidase inks with lateral feature sizes between ~5 to 1000 μm in width, and that the glucose oxidase was still active after printing. The thickness of the permselective layer was optimized to obtain a linear response for glucose concentrations up to 32 mM and no response to acetaminophen, a common interfering compound, was observed. The use of such thin polyimide substrates allow wrapping of the sensors around catheters with high radius of curvature ~250 μm, where additive and microfabrication methods may allow significant cost reductions. PMID:26634186

Silica nanoparticles on front glass for efficiency enhancement in superstrate-type amorphous silicon solar cells

NASA Astrophysics Data System (ADS)

Das, Sonali; Banerjee, Chandan; Kundu, Avra; Dey, Prasenjit; Saha, Hiranmay; Datta, Swapan K.

2013-10-01

Antireflective coating on front glass of superstrate-type single junction amorphous silicon solar cells (SCs) has been applied using highly monodispersed and stable silica nanoparticles (NPs). The silica NPs having 300 nm diameter were synthesized by Stober technique where the size of the NPs was controlled by varying the alcohol medium. The synthesized silica NPs were analysed by dynamic light scattering technique and Fourier transform infrared spectroscopy. The NPs were spin coated on glass side of fluorinated tin oxide (SnO2: F) coated glass superstrate and optimization of the concentration of the colloidal solution, spin speed and number of coated layers was done to achieve minimum reflection characteristics. An estimation of the distribution of the NPs for different optimization parameters has been done using field-emission scanning electron microscopy. Subsequently, the transparent conducting oxide coated glass with the layer having the minimum reflectance is used for fabrication of amorphous silicon SC. Electrical analysis of the fabricated cell indicates an improvement of 6.5% in short-circuit current density from a reference of 12.40 mA cm-2 while the open circuit voltage and the fill factor remains unaltered. A realistic optical model has also been proposed to gain an insight into the system.

Low Hysteresis Carbon Nanotube Transistors Constructed via a General Dry-Laminating Encapsulation Method on Diverse Surfaces.

PubMed

Yang, Yi; Wang, Zhongwu; Xu, Zeyang; Wu, Kunjie; Yu, Xiaoqin; Chen, Xiaosong; Meng, Yancheng; Li, Hongwei; Qiu, Song; Jin, Hehua; Li, Liqiang; Li, Qingwen

2017-04-26

Electrical hysteresis in carbon nanotube thin-film transistor (CNTTFT) due to surface adsorption of H 2 O/O 2 is a severe obstacle for practical applications. The conventional encapsulation methods based on vacuum-deposited inorganic materials or wet-coated organic materials have some limitations. In this work, we develop a general and highly efficient dry-laminating encapsulation method to reduce the hysteresis of CNTTFTs, which may simultaneously realize the construction and encapsulation of CNTTFT. Furthermore, by virtue of dry procedure and wide compatibility of PMMA, this method is suitable for the construction of CNTTFT on diverse surface including both inorganic and organic dielectric materials. Significantly, the dry-encapsulated CNTTFT exhibits very low or even negligible hysteresis with good repeatability and air stability, which is greatly superior to the nonencapsulated and wet-encapsulated CNTTFT with spin-coated PMMA. The dry-laminating encapsulation strategy, a kind of technological innovation, resolves a significant problem of CNTTFT and therefore will be promising in facile transferring and packaging the CNT films for high-performance optoelectronic devices.

Removing seed coat fragments with a lint cleaner grid bar air knife

USDA-ARS?s Scientific Manuscript database

Seed coat fragments (SCF) in ginned lint cause spinning problems at the textile mill and undesirable defects in finished goods. Work continued on developing an air knife that may help remove SCF from ginned lint. The air knife is mounted on the 1st lint cleaner grid bar of a saw-type lint cleaner,...

Construction of poly(lactic-co-glycolic acid)/ZnO nanorods/Ag nanoparticles hybrid coating on Ti implants for enhanced antibacterial activity and biocompatibility.

PubMed

Xiang, Yiming; Li, Jun; Liu, Xiangmei; Cui, Zhenduo; Yang, Xianjin; Yeung, K W K; Pan, Haobo; Wu, Shuilin

2017-10-01

Poly(lactic-co-glycolic acid)/Ag/ZnO nanorods coating were successfully prepared on the surface of Ti metallic implants using a hydrothermal method and subsequent spin-coating of mixtures of poly(lactic-co-glycolic acid) and silver nanoparticles. The poly(lactic-co-glycolic acid)/Ag/ZnO nanorods coating exhibited excellent antibacterial efficacy of over 96% against both Staphylococcus aureus and Escherichia coli when the initial content of Ag nanoparticles was over 3wt%. In addition, the release of both silver and zinc could last for over a hundred days due to the enwrapping of poly(lactic-co-glycolic acid). Proliferation of mouse calvarial cells exhibited minimal cytotoxicity on the poly(lactic-co-glycolic acid)/Ag/ZnO coating with an initial content of Ag nanoparticles of 1wt% and 3wt%, while it inhibited cell proliferation once this value was increased to 6wt%. The results revealed that this poly(lactic-co-glycolic acid)/Ag/ZnO composite could provide a long-lasting antibacterial approach and good cytocompatibility, thus exhibiting considerable potential for biomedical application in orthopedic and dental implants with excellent self-antibacterial activity and good biocompatibility. Copyright © 2017 Elsevier B.V. All rights reserved.

Immersion transmission ellipsometry (ITE): a new method for the precise determination of the 3D indicatrix of thin films

NASA Astrophysics Data System (ADS)

Jung, C. C.; Stumpe, J.

2005-02-01

The new method of immersion transmission ellipsometry (ITE) [1] has been developed. It allows the highly accurate determination of the absolute three-dimensional (3D) refractive indices of anisotropic thin films. The method is combined with conventional ellipsometry in transmission and reflection, and the thickness determination of anisotropic films solely by optical methods also becomes more accurate. The method is applied to the determination of the 3D refractive indices of thin spin-coated films of an azobenzene-containing liquid-crystalline copolymer. The development of the anisotropy in these films by photo-orientation and subsequent annealing is demonstrated. Depending on the annealing temperature, oblate or prolate orders are generated.

Humidity sensing properties of Al-doped zinc oxide coating films

NASA Astrophysics Data System (ADS)

Saidi, S. A.; Mamat, M. H.; Ismail, A. S.; Malek, M. F.; Yusoff, M. M.; Sin, N. D. Md.; Zoolfakar, A. S.; Khusaimi, Z.; Rusop, M.

2018-05-01

Humidity sensor was fabricated using Al-doped zinc oxide (ZnO) coating films through spin-coating at room temperature. The sensing mechanism was discussed based on their nanostructures, such as surface area and porous nanostructures. Surface area and water adsorption are an important component in the low humidity, while at high humidity, porous nanostructures and capillary condensation become important. The results showed that the sensitivity of the Al-doped ZnO coating improved compared to that of the Al-doped ZnO nanorod arrays, with values of 7.38 at 40% to 90%RH (Relative humidity). All these results indicated that Al-doped ZnO coating had high potential for humidity-sensor applications.

Sustained release of melatonin from TiO2 nanotubes for modulating osteogenic differentiation of mesenchymal stem cells in vitro.

PubMed

Lai, Min; Jin, Ziyang; Tang, Qiang; Lu, Min

2017-10-01

To control the sustained release of melatonin and modulate the osteogenic differentiation of mesenchymal stem cells (MSCs), melatonin was firstly loaded onto TiO 2 nanotubes by direct dropping method, and then a multilayered film was coated by a spin-assisted layer-by-layer technique, which was composed of chitosan (Chi) and gelatin (Gel). Successful fabrication was characterized by field emission scanning electron microscopy, atomic force microscope, X-ray photoelectron spectroscopy and contact angle measurement, respectively. The efficient sustained release of melatonin was measured by UV-visible-spectrophotometer. After 2 days of culture, well-spread morphology was observed in MSCs grown on the Chi/Gel multilayer-coated melatonin-loaded TiO 2 nanotube substrates as compared to different groups. After 4, 7, 14 and 21 days of culture, the multilayered-coated melatonin-loaded TiO 2 nanotube substrates increased cell proliferation, increased alkaline phosphatase (ALP) and mineralization, increased expression of mRNA levels for runt-related transcription factor 2 (Runx2), ALP, osteopontin (OPN) and osteocalcin (OC), indicative of osteoblastic differentiation. These results demonstrated that Chi/Gel multilayer-coated melatonin-loaded TiO 2 nanotube substrates promoted cell adhesion, spreading, proliferation and differentiation and could provide an alternative fabrication method for titanium-based implants to enhance the osteointegration between bone tissues and implant surfaces.

Effects of magnetic impurity scattering on superfluid 3He in aerogel

NASA Astrophysics Data System (ADS)

Aoyama, Kazushi; Ikeda, Ryusuke

2009-02-01

We investigate impurity effects on superfluid 3He in aerogel whose surface is not coated with 4He, different from most experimental situations. In systems with no 4He coating, spins of solid 3He absorbed on the aerogel surface are active and interact with spins of quasiparticles relevant to superfluidity and, for this reason, such an aerogel is treated as magnetic scatterers. It is found that, in the ABM pairing state affected by magnetic scatterings, not only the l-vector but also the d-vector has no long-ranged orientational order, and that the strong-coupling correction due to impurity scatterings is less suppressed than that in the nonmagnetic case, implying an expansion of the A-like phase region.

Optical properties of micro and nano LiNbO3 thin film prepared by spin coating

NASA Astrophysics Data System (ADS)

Fakhri, Makram A.; Salim, Evan T.; Abdulwahhab, Ahmed W.; Hashim, U.; Salim, Zaid T.

2018-07-01

This paper deals with preparing of Lithium-Niobate thin films based on Sol-Gel technique on a substrate made of quartz, samples have been deposited under three different stirrer times. At 3000 round per minute of spin coating strategy, the deposition processes have been accomplished. The results showed an enhancement in the crystalline structure of the prepared samples with increasing the duration of stirrer time. The AFM measurement has assured that the structure of the prepared samples is more regular distributed, homogeneous and crack-free in their structures. Further, measurements and calculations of lattice constant, energy band gap, refractive index, and optical dielectric constant are also considered and agreed with experimental data collected by the characterized samples.

Morphological impact of zinc oxide layers on the device performance in thin-film transistors.

PubMed

Faber, Hendrik; Klaumünzer, Martin; Voigt, Michael; Galli, Diana; Vieweg, Benito F; Peukert, Wolfgang; Spiecker, Erdmann; Halik, Marcus

2011-03-01

Zinc oxide thin-films are prepared either by spin coating of an ethanolic dispersion of nanoparticles (NP, diameter 5 nm) or by spray pyrolysis of a zinc acetate dihydrate precursor. High-resolution electron microscopy studies reveal a monolayer of particles for the low temperature spin coating approach and larger crystalline domains of more than 30 nm for the spray pyrolysis technique. Thin-film transistor devices (TFTs) based on spray pyrolysis films exhibit higher electron mobilities of up to 24 cm2 V(-1) s(-1) compared to 0.6 cm2 V(-1) s(-1) for NP based TFTs. These observations were dedicated to a reduced number of grain boundaries within the transistor channel.

Electrochromic NiO thin films prepared by spin coating

NASA Astrophysics Data System (ADS)

Özütok, F.; Demiri, S.; Özbek, E.

2017-02-01

Recently, smart windows are very important because they are often being used in smart buildings and car glasses (windows). At this point, producing effective electrochromic materials is so necessary. In this study, we produced NiO thin films by using spin coating technique on In-doped SnO2 (ITO) substrate. Nickel proportions of these nickel oxide (NiO) films are 3, 5 and 7 %. Nickel acetate tetrahydrate is the initial solution and solvents are ethylene gl ycol and n-hexzane. Structural properties and surface images are investigated by using x-ray diffactometer (XRD) and scanning electron microscope (SEM) device, respectively. In addition, electrochemical behavior is investigated by cyclic voltammetry. A correlation between surface morphology and electrochromic performance was observed as well.

Synthesis and film formation of furfuryl- and maleimido carbonic acid derivatives of dextran.

PubMed

Elschner, Thomas; Obst, Franziska; Stana-Kleinschek, Karin; Kargl, Rupert; Heinze, Thomas

2017-04-01

Carbonic acid derivatives of dextran possessing furfuryl- and maleimido moieties were synthesized and processed into thin films by spin coating. First, products with different degrees of substitution (DS) of up to 3.0 and substitution patterns were obtained and characterized by NMR- and FTIR spectroscopy, as well as elemental analysis. Thin films possessing maleimide groups were obtained by spin coating of maleimido dextran (furan-protected) and dextran furfuryl carbamate that was converted with bismaleimide. The removal of the protecting group (furan) on the thin film was monitored by QCM-D and compared with gravimetric analysis of the bulk material. Film morphology and wettability were determined by means of AFM and contact angle measurements. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fabrication and characterization of nanostructured Mg-doped CdS/AAO nanoporous membrane for sensing applications

NASA Astrophysics Data System (ADS)

Shaban, Mohamed; Mustafa, Mona; Hamdy, Hany

2016-04-01

In this study, Mg-doped CdS nanostructure was deposited onto anodic aluminum oxide (AAO) membrane substrate using sol-gel spin coating method. The AAO membrane was prepared by a two-step anodization process combined with pore widening process. The morphology, chemical composition, and structure of the spin- coated CdS nanostructure have been studied. The morphology of the fabricated AAO membrane and the deposited Mg-doped CdS nanostructure was investigated using scanning electron microscopy (SEM). The SEM of AAO illustrates a typical hexagonal and smooth nanoporous alumina membrane with interpore distance of ~ 100 nm, the pore diameter of ~ 60 nm. SEM of Mgdoped CdS shows porous nanostructured film of CdS nanoparticles. This film well adherents and covers the AAO substrate. The energy dispersive X-ray (EDX) pattern exhibits the signals of Al, O from AAO membrane and Mg, Cd, and S from the deposited CdS. This indicates the high purity of the fabricated membrane and the deposited Mg-doped CdS nanostructure. Using X-ray diffraction (XRD) pattern, Scherrer equation was used to calculate the average crystallite size. Additionally, the texture coefficients and density of dislocations were calculated. The fabricated CdS/AAO was applied to detect glucose of different concentrations. The proposed method has some advantages such as simple technology, low cost of processing, and high throughput. All of these factors facilitate the use of the prepared films in sensing applications.

Spin-Coating and Characterization of Multiferroic MFe2O4 (M=Co, Ni) / BaTiO3 Bilayers

NASA Astrophysics Data System (ADS)

Quandt, Norman; Roth, Robert; Syrowatka, Frank; Steimecke, Matthias; Ebbinghaus, Stefan G.

2016-01-01

Bilayer films of MFe2O4 (M=Co, Ni) and BaTiO3 were prepared by spin coating of N,N-dimethylformamide/acetic acid solutions on platinum coated silicon wafers. Five coating steps were applied to get the desired thickness of 150 nm for both the ferrite and perovskite layer. XRD, IR and Raman spectroscopy revealed the formation of phase-pure ferrite spinels and BaTiO3. Smooth surfaces with roughnesses in the order of 3 to 5 nm were found in AFM investigations. Saturation magnetization of 347 emu cm-3 for the CoFe2O4/BaTiO3 and 188 emu cm-3 for the NiFe2O4/BaTiO3 bilayer, respectively were found. For the CoFe2O4/BaTiO3 bilayer a strong magnetic anisotropy was observed with coercivity fields of 5.1 kOe and 3.3 kOe (applied magnetic field perpendicular and parallel to film surface), while for the NiFe2O4/BaTiO3 bilayer this effect is less pronounced. Saturated polarization hysteresis loops prove the presence of ferroelectricity in both systems.

High-Performing Polycarbazole Derivatives for Efficient Solution-Processing of Organic Solar Cells in Air.

PubMed

Burgués-Ceballos, Ignasi; Hermerschmidt, Felix; Akkuratov, Alexander V; Susarova, Diana K; Troshin, Pavel A; Choulis, Stelios A

2015-12-21

The application of conjugated materials in organic photovoltaics (OPVs) is usually demonstrated in lab-scale spin-coated devices that are processed under controlled inert conditions. Although this is a necessary step to prove high efficiency, testing of promising materials in air should be done in the early stages of research to validate their real potential for low-cost, solution-processed, and large-scale OPVs. Also relevant for approaching commercialization needs is the use of printing techniques that are compatible with upscaling. Here, solution processing of organic solar cells based on three new poly(2,7-carbazole) derivatives is efficiently transferred, without significant losses, to air conditions and to several deposition methods using a simple device architecture. High efficiencies in the range between 5.0 % and 6.3 % are obtained in (rigid) spin-coated, doctor-bladed, and (flexible) slot-die-coated devices, which surpass the reference devices based on poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT). In contrast, inkjet printing does not provide reliable results with the presented polymers, which is attributed to their high molecular weight. When the device area in the best-performing system is increased from 9 mm(2) to 0.7 cm(2), the efficiency drops from 6.2 % to 5.0 %. Photocurrent mapping reveals inhomogeneous current generation derived from changes in the thickness of the active layer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inverse opal photonic crystal of chalcogenide glass by solution processing.

PubMed

Kohoutek, Tomas; Orava, Jiri; Sawada, Tsutomu; Fudouzi, Hiroshi

2011-01-15

Chalcogenide opal and inverse opal photonic crystals were successfully fabricated by low-cost and low-temperature solution-based process, which is well developed in polymer films processing. Highly ordered silica colloidal crystal films were successfully infilled with nano-colloidal solution of the high refractive index As(30)S(70) chalcogenide glass by using spin-coating method. The silica/As-S opal film was etched in HF acid to dissolve the silica opal template and fabricate the inverse opal As-S photonic crystal. Both, the infilled silica/As-S opal film (Δn ~ 0.84 near λ=770 nm) and the inverse opal As-S photonic structure (Δn ~ 1.26 near λ=660 nm) had significantly enhanced reflectivity values and wider photonic bandgaps in comparison with the silica opal film template (Δn ~ 0.434 near λ=600 nm). The key aspects of opal film preparation by spin-coating of nano-colloidal chalcogenide glass solution are discussed. The solution fabricated "inorganic polymer" opal and the inverse opal structures exceed photonic properties of silica or any organic polymer opal film. The fabricated photonic structures are proposed for designing novel flexible colloidal crystal laser devices, photonic waveguides and chemical sensors. Copyright © 2010 Elsevier Inc. All rights reserved.

The Optical Properties of Thin Film Reduced Graphene Oxide/Poly (3,4 Ethylenedioxtriophene):Poly (Styrene Sulfonate)(PEDOT:PSS) Fabricated by Spin Coating

NASA Astrophysics Data System (ADS)

Rokmana, Arinta W.; Asriani, A.; Suhendar, H.; Triyana, K.; Kusumaatmaja, A.; Santoso, I.

2018-04-01

Reduced Graphene Oxide (rGO) has been successfully synthesized from Graphite powder through chemical process using modified Hummers method by removing NaNO3 from reaction formula. Hydrazine hydrate 80 wt% has been chosen as reductor to eliminate the epoxy group in GO. FTIR and Uv-Vis spectroscopy result showed that Graphene Oxide (GO) and rGO were formed. Our produced rGO then used to fabricated the composite thin film rGO/PEDOT:PSS by spin coating at room temperature. The optical constant of thin film rGO/PEDOT:PSS were calculated from the absorbance spectrum of Uv-Visible spectra. The result showed that the value of coefficient absorbance of rGO dropped from 4.7×106 m-1 to 1.3×106 m-1 after doped with 0.02 mL PEDOT:PSS, then increase with the addition volume concentration of PEDOT:PSS. The value of extinction coefficient decrease from 0.31 to 0.08 after rGO doped with 0.02 ml PEDOT:PSS and then increase with the addition concentration of PEDOT:PSS. Our result show that thin film rGO/PEDOT:PSS was more transparent than that of thin film rGO.

The photovoltaic efficiency of the fabrication of copolymer P3HT:PCBM on different thickness nano-anatase titania as solar cell

NASA Astrophysics Data System (ADS)

Lazim, Haidar Gazy; Ajeel, Khalid I.; Badran, Hussain A.

2015-06-01

Organic solar cells based on (3-hexylthiophene):[6,6]-phenyl C61-butyric acid methylester (P3HT:PCBM) bulk heterojunction (BHJ) with an inverted structure have been fabricated using nano-anatase crystalline titanium dioxide (TiO2) as their electron transport layer, which was prepared on the indium tin oxide coated glass (ITO-glass), silicon wafer and glass substrates by sol-gel method at different spin speed by using spin-coating (1000, 2000 and 3000 rpm) for nano-thin film 58, 75 and 90 nm respectively. The effect of thickness on the surface morphology and optical properties of TiO2 layer were investigated by atomic force microscopy (AFM), X-ray diffraction and UV-visible spectrophotometer. The optical band gap of the films has been found to be in the range 3.63-3.96 eV for allowed direct transition and to be in the range 3.23-3.69 eV for forbidden direct transition to the different TiO2 thickness. The samples were examined to feature current and voltages darkness and light extraction efficiency of the solar cell where they were getting the highest open-circuit voltage, Voc, and power conversion efficiency were 0.66% and 0.39% fabricated with 90 nm respectively.

Thin-film encapsulation of organic electronic devices based on vacuum evaporated lithium fluoride as protective buffer layer

NASA Astrophysics Data System (ADS)

Peng, Yingquan; Ding, Sihan; Wen, Zhanwei; Xu, Sunan; Lv, Wenli; Xu, Ziqiang; Yang, Yuhuan; Wang, Ying; Wei, Yi; Tang, Ying

2017-03-01

Encapsulation is indispensable for organic thin-film electronic devices to ensure reliable operation and long-term stability. For thin-film encapsulating organic electronic devices, insulating polymers and inorganic metal oxides thin films are widely used. However, spin-coating of insulating polymers directly on organic electronic devices may destroy or introduce unwanted impurities in the underlying organic active layers. And also, sputtering of inorganic metal oxides may damage the underlying organic semiconductors. Here, we demonstrated that by utilizing vacuum evaporated lithium fluoride (LiF) as protective buffer layer, spin-coated insulating polymer polyvinyl alcohol (PVA), and sputtered inorganic material Er2O3, can be successfully applied for thin film encapsulation of copper phthalocyanine (CuPc)-based organic diodes. By encapsulating with LiF/PVA/LiF trilayer and LiF/Er2O3 bilayer films, the device lifetime improvements of 10 and 15 times can be achieved. These methods should be applicable for thin-film encapsulation of all kinds of organic electronic devices. Moisture-induced hole trapping, and Al top electrode oxidation are suggest to be the origins of current decay for the LiF/PVA/LiF trilayer and LiF/Er2O3 bilayer films encapsulated devices, respectively.

Spin-coating deposition of PbS and CdS thin films for solar cell application

NASA Astrophysics Data System (ADS)

Patel, Jayesh; Mighri, Frej; Ajji, Abdellah; Tiwari, Devendra; Chaudhuri, Tapas K.

2014-12-01

In this work, we describe a simple spin-coating deposition technique for lead sulphide (PbS) and cadmium sulphide (CdS) films from a methanolic metal-thiourea complex. The characterization of the films by X-ray diffraction and X-ray photoelectron spectroscopy techniques revealed that pure cubic phase PbS and CdS layers were formed via this method. As shown by atomic force microscopy and scanning electron microscopy results, both films were homogeneous and presented a smooth surface. Optical properties showed that the energy band gap of PbS and CdS films were around 1.65 and 2.5 eV, respectively. The PbS film is p-type in nature with an electrical conductivity of around 0.8 S/cm. The hole concentration and mobility were 2.35 × 1018 cm-3 and 2.16 × 10-3 cm2/V/s, respectively, as determined from Hall measurement. Both films were used to develop a thin film solar cell device of graphite/PbS/CdS/ITO/glass. Device characterization showed the power conversion efficiency of around 0.24 %. The corresponding open circuit voltage, short circuit current and fill factor were 0.570 V, 1.32 mA/cm2 and 0.32, respectively.

Spin-on bottom antireflective coating defect reduction by proper filter selection and process optimization

NASA Astrophysics Data System (ADS)

Brakensiek, Nickolas L.; Kidd, Brian; Mesawich, Michael; Stevens, Don, Jr.; Gotlinsky, Barry

2003-06-01

A design of experiment (DOE) was implemented to show the effects of various point of use filters on the coat process. The DOE takes into account the filter media, pore size, and pumping means, such as dispense pressure, time, and spin speed. The coating was executed on a TEL Mark 8 coat track, with an IDI M450 pump, and PALL 16 stack Falcon filters. A KLA 2112 set at 0.69 μm pixel size was used to scan the wafers to detect and identify the defects. The process found for DUV42P to maintain a low defect coating irrespective of the filter or pore size is a high start pressure, low end pressure, low dispense time, and high dispense speed. The IDI M450 pump has the capability to compensate for bubble type defects by venting the defects out of the filter before the defects are in the dispense line and the variable dispense rate allows the material in the dispense line to slow down at the end of dispense and not create microbubbles in the dispense line or tip. Also the differential pressure sensor will alarm if the pressure differential across the filter increases over a user-determined setpoint. The pleat design allows more surface area in the same footprint to reduce the differential pressure across the filter and transport defects to the vent tube. The correct low defect coating process will maximize the advantage of reducing filter pore size or changing the filter media.

Pbar Beam Stacking in the Recycler by Longitudinal Phase-space Coating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhat, C. M.

2013-08-06

Barrier rf buckets have brought about new challenges in longitudinal beam dynamics of charged particle beams in synchrotrons and at the same time led to many new remarkable prospects in beam handling. In this paper, I describe a novel beam stacking scheme for synchrotrons using barrier buckets without any emittance dilution to the beam. First I discuss the general principle of the method, called longitudinal phase-space coating. Multi-particle beam dynamics simulations of the scheme applied to the Recycler, convincingly validates the concepts and feasibility of the method. Then I demonstrate the technique experimentally in the Recycler and also use itmore » in operation. A spin-off of this scheme is its usefulness in mapping the incoherent synchrotron tune spectrum of the beam particles in barrier buckets and producing a clean hollow beam in longitudinal phase space. Both of which are described here in detail with illustrations. The beam stacking scheme presented here is the first of its kind.« less

Spin-hall-active platinum thin films grown via atomic layer deposition

NASA Astrophysics Data System (ADS)

Schlitz, Richard; Amusan, Akinwumi Abimbola; Lammel, Michaela; Schlicht, Stefanie; Tynell, Tommi; Bachmann, Julien; Woltersdorf, Georg; Nielsch, Kornelius; Goennenwein, Sebastian T. B.; Thomas, Andy

2018-06-01

We study the magnetoresistance of yttrium iron garnet/Pt heterostructures in which the Pt layer was grown via atomic layer deposition (ALD). Magnetotransport experiments in three orthogonal rotation planes reveal the hallmark features of spin Hall magnetoresistance. To estimate the spin transport parameters, we compare the magnitude of the magnetoresistance in samples with different Pt thicknesses. We check the spin Hall angle and the spin diffusion length of the ALD Pt layers against the values reported for high-quality sputter-deposited Pt films. The spin diffusion length of 1.5 nm agrees well with that of platinum thin films reported in the literature, whereas the spin Hall magnetoresistance Δ ρ / ρ = 2.2 × 10 - 5 is approximately a factor of 20 smaller compared to that of our sputter-deposited films. Our results demonstrate that ALD allows fabricating spin-Hall-active Pt films of suitable quality for use in spin transport structures. This work provides the basis to establish conformal ALD coatings for arbitrary surface geometries with spin-Hall-active metals and could lead to 3D spintronic devices in the future.

Thiol-modified MoS2 nanosheets as a functional layer for electrical bistable devices

NASA Astrophysics Data System (ADS)

Li, Guan; Tan, Fenxue; Lv, Bokun; Wu, Mengying; Wang, Ruiqi; Lu, Yue; Li, Xu; Li, Zhiqiang; Teng, Feng

2018-01-01

Molybdenum disulfide nanosheets have been synthesized by one-pot method using 1-ODT as sulfur source and surfactant. The structure, morphology and optical properties of samples were investigated by XRD, FTIR, Abs spectrum and TEM patterns. The XRD pattern indicated that the as-obtained MoS2 belong to hexagonal system. The as-obtained MoS2 nanosheets blending with PVK could be used to fabricate an electrically bistable devices through a simple spin-coating method and the device exhibited an obvious electrical bistability properties. The charge transport mechanism of the device was discussed based on the filamentary switching models.

Transfer Printing Method to Obtain Polarized Light Emission in Organic Light-Emitting Device

NASA Astrophysics Data System (ADS)

Noh, Hee Yeon; Park, Chang-sub; Park, Ji-Sub; Kang, Shin-Won; Kim, Hak-Rin

2012-06-01

We demonstrate a transfer printing method to obtain polarized light emission in organic light-emitting devices (OLEDs). On a rubbed self-assembled monolayer (SAM), a spin-coated liquid crystalline light-emissive polymer is aligned along the rubbing direction because of the anisotropic interfacial intermolecular interaction. Owing to the low surface energy of the SAM surface, the light-emissive layer was easily transferred to a patterned poly(dimethylsiloxane) (PDMS) stamp surface without degrading the ordering. Finally, a polarized light-emissive OLED device was prepared by transferring the patterned light-emissive layer to the charge transport layer of the OLED structure.

Preparation of titanium dioxide films by sol-gel route for gas sensors

NASA Astrophysics Data System (ADS)

Schiopu, Vasilica; Matei, Alina; Cernica, Ileana; Podaru, Cecilia

2009-01-01

Semiconductor oxides such as SnO2, TiO2, WO3, ZnO2 etc. have been shown to be useful as gas sensor materials for monitoring various pollutant gases like H2S, NOx, NH3 etc. In this work, we would like to present the preparation of titanium dioxide films for gas sensor application, via the sol-gel technique. The coating solution was prepared by using titanium isopropoxide precursor, which was hydrolyzed with distilled water under the catalytic effect of different acids (HNO3, HCl or CH3COOH). Titanium dioxide films have been deposited using spin coating method and then synthesized at different temperatures. Fourier transform infrared spectroscopy observation has been used to analyze the sol-gel process. The morphology and the structure of the thin films were analyzed.

Facile Synthesis of Porous Silicon Nanofibers by Magnesium Reduction for Application in Lithium Ion Batteries.

PubMed

Cho, Daehwan; Kim, Moonkyoung; Hwang, Jeonghyun; Park, Jay Hoon; Joo, Yong Lak; Jeong, Youngjin

2015-12-01

We report a facile fabrication of porous silicon nanofibers by a simple three-stage procedure. Polymer/silicon precursor composite nanofibers are first fabricated by electrospinning, a water-based spinning dope, which undergoes subsequent heat treatment and then reduction using magnesium to be converted into porous silicon nanofibers. The porous silicon nanofibers are coated with a graphene by using a plasma-enhanced chemical vapor deposition for use as an anode material of lithium ion batteries. The porous silicon nanofibers can be mass-produced by a simple and solvent-free method, which uses an environmental-friendly polymer solution. The graphene-coated silicon nanofibers show an improved cycling performance of a capacity retention than the pure silicon nanofibers due to the suppression of the volume change and the increase of electric conductivity by the graphene.

Rapid and Facile Formation of P3HT Organogels via Spin Coating: Tuning Functional Properties of Organic Electronic Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Cameron S.; Yin, Wen; Holt, Adam P.

Poly(3-hexyl thiophene) (P3HT) is widely regarded as the benchmark polymer when studying the physics of conjugated polymers used in organic electronic devices. P3HT can self-assemble via stacking of its backbone, leading to an assembly and growth of P3HT fi brils into 3D percolating organogels. These structures are capable of bridging the electrodes, providing multiple pathways for charge transport throughout the active layer. Here, a novel set of conditions is identified and discussed for P3HT organogel network formation via spin coating by monitoring the spin-coating process from various solvents. The development of organogel formation is detected by in situ static lightmore » scattering, which measures both the thinning rate by refl ectance and structural development in the fi lm via off-specular scattering during fi lm formation. Optical microscopy and thermal annealing experiments provide ex situ confi rmation of organogel fabrication. The role of solution characteristics, including solvent boiling point, P3HT solubility, and initial P3HT solution concentration on organogel formation, is examined to correlate these parameters to the rate of film formation, organogel-onset concentration, and overall network size. The correlation of film properties to the fabrication parameters is also analyzed within the context of the hole mobility and density-of-states measured by impedance spectroscopy.« less

In-vitro bioactivity, biocorrosion and antibacterial activity of silicon integrated hydroxyapatite/chitosan composite coating on 316 L stainless steel implants.

PubMed

Sutha, S; Kavitha, K; Karunakaran, G; Rajendran, V

2013-10-01

A simple and effective ultrasonication method was applied for the preparation of 0, 0.4, 0.8, 1.0 and 1.6 wt% silicon substituted hydroxyapatite (HAp) (SH). The Ca/P ratio of the synthesised SH nanoparticles were in the range of 1.58-1.70. Morphological changes were noticed in HAp with respect to the amount of Si from 0 to 1.6 wt%. The morphology of the particles changed from spherical shape to rod-like morphology with respect to the amount of Si which was confirmed using transmission electron microscopy. X-ray diffraction studies confirm the formation of phase pure SH nanoparticles without any secondary phase. Chitosan (CTS) blended SH nanocomposites coating on surgical grade 316 L stainless steel (316 L SS) implant was made by spin coating technique. The surface of the coated implant was characterised using scanning electron microscopy which confirms the uniform coating without cracks and pores. The increased corrosion resistance of the 1.6 wt% of SH/CTS-coated SS implant in the simulated body fluid (SBF) indicates the long-term biostability of SH composite-coated ceramics in vitro than the 0 wt% SH/CTS. The testing of SH/CTS nanocomposites with gram-positive and gram-negative bacterial strains confirms that the antibacterial ability improves with the higher substitution of Si. In addition, formation of bone-like apatite layer on the SH/CTS-coated implant in SBF was studied through SEM analysis and it confirms the ability to increase the HAp formation on the surface of 1.0 wt% SH/CTS-coated 316 L SS implant. Copyright © 2013 Elsevier B.V. All rights reserved.

Enhanced room-temperature magnetoresistance in self-assembled Ag-coated multiphasic chromium oxide nanocomposites.

PubMed

Dwivedi, S; Biswas, S

2016-09-14

Self-assembled Ag-coated multiphasic diluted magnetic chromium oxide nanocomposites were developed by a facile chemical synthesis route involving a reaction of CrO3 in the presence of Ag(+) ions in an aqueous solution of poly-vinyl alcohol (PVA) and sucrose. The tiny ferromagnetic single domains of tetragonal and orthorhombic CrO2 (t-CrO2 and o-CrO2) embedded in a dominantly insulating matrix of antiferromagnetic Cr2O3 and Cr3O8, and paramagnetic CrO3 and Cr2O, with a correlated diamagnetic thin and discontinuous shell layer of Ag efficiently tailor useful magnetic and room-temperature magnetoresistance (RTMR) properties. The t-CrO2, o-CrO2, possible canted ferromagnetism due to spin disorder in the matrix components, and the associated exchange interactions are the elements responsible for the observed ferromagnetism in the composite structure. The chain of ferromagnetic centers embedded in the composite matrix constitutes a type of magnetic tunnel junction through which spin-polarized electrons can effectively move without significant local interruptions. Electrical transport measurements showed that the spin-dependent tunneling (SDT) mechanism in the engineered microstructure of the nanocomposites exists even at room temperature (RT). A typical sample unveils a markedly enhanced RTMR-value, e.g., -80% at an applied field (H) of 3 kOe, compared to the reported values for compacted CrO2 powders or composites. The enhanced RTMR-value observed in the Coulomb blockade regime appears not only due to the considerably suppressed spin flipping at RT but primarily due to a highly effective SDT mechanism through an interlinked structure of Ag-coated multiphasic chromium oxide nanocomposites.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jenner, Elliot; Barbier, Charlotte N; D'Urso, Brian R

Robust and easily produced Superhydrophobic surfaces are of great interest for mechanical applications, including drag reduction and MEMS. We produce novel superhydrophobic surfaces with several different coatings and tested the durability of each of these coatings with respect to long term immersion in water in order to determine the most long-lasting surface preparation. A pair of combinations of spin on polymers, surface features, and adhesion promoters was found that provide long term durability.

Sol-gel-derived double-layered nanocrystal memory

NASA Astrophysics Data System (ADS)

Ko, Fu-Hsiang; You, Hsin-Chiang; Lei, Tan-Fu

2006-12-01

The authors have used the sol-gel spin-coating method to fabricate a coexisting hafnium silicate and zirconium silicate double-layered nanocrystal (NC) memories. From transmission electron microscopic and x-ray photoelectron spectroscopic analyses, the authors determined that the hafnium silicate and zirconium silicate NCs formed after annealing at 900°C for 1min. When using channel hot electron injection for charging and band-to-band tunneling-induced hot hole injection for discharging, the NC memories exhibited superior Vth shifting because of the higher probability for trapping the charge carrier.

An organic surface modifier to produce a high work function transparent electrode for high performance polymer solar cells.

PubMed

Choi, Hyosung; Kim, Hak-Beom; Ko, Seo-Jin; Kim, Jin Young; Heeger, Alan J

2015-02-04

Modification of an ITO electrode with small-molecule organic surface modifier, 4-chloro-benzoic acid (CBA), via a simple spin-coating method produces a high-work-function electrode with high transparency and a hydrophobic surface. As an alternative to PEDOT:PSS, CBA modification achieves efficiency enhancement up to 8.5%, which is attributed to enhanced light absorption within the active layer and smooth hole transport from the active layer to the anode. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Growth of long triisopropylsilylethynyl pentacene (TIPS-PEN) nanofibrils in a polymer thin film during spin-coating.

PubMed

Park, Minwoo; Min, Yuho; Lee, Yu-Jeong; Jeong, Unyong

2014-03-01

This study demonstrates the growth of long triisopropylsilyethynyl pentacene (TIPS-PEN) nanofibrils in a thin film of a crystalline polymer, poly(ε-caprolactone) (PCL). During spin-coating, TIPS-PEN molecules are locally extracted around the PCL grain boundaries and they crystallize into [010] direction forming long nanofibrils. Molecular weight of PCL and weight fraction (α) of TIPS-PEN in PCL matrix are key factors to the growth of nanofibrils. Long high-quality TIPS-PEN nanofibrils are obtained with high-molecular-weight PCL and at the α values in the range of 0.03-0.1. The long nanofibrils are used as an active layer in a field-effect organic transistor. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-throughput preparation of complex multi-scale patterns from block copolymer/homopolymer blend films

NASA Astrophysics Data System (ADS)

Park, Hyungmin; Kim, Jae-Up; Park, Soojin

2012-02-01

A simple, straightforward process for fabricating multi-scale micro- and nanostructured patterns from polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP)/poly(methyl methacrylate) (PMMA) homopolymer in a preferential solvent for PS and PMMA is demonstrated. When the PS-b-P2VP/PMMA blend films were spin-coated onto a silicon wafer, PS-b-P2VP micellar arrays consisting of a PS corona and a P2VP core were formed, while the PMMA macrodomains were isolated, due to the macrophase separation caused by the incompatibility between block copolymer micelles and PMMA homopolymer during the spin-coating process. With an increase of PMMA composition, the size of PMMA macrodomains increased. Moreover, the P2VP blocks have a strong interaction with a native oxide of the surface of the silicon wafer, so that the P2VP wetting layer was first formed during spin-coating, and PS nanoclusters were observed on the PMMA macrodomains beneath. Whereas when a silicon surface was modified with a PS brush layer, the PS nanoclusters underlying PMMA domains were not formed. The multi-scale patterns prepared from copolymer micelle/homopolymer blend films are used as templates for the fabrication of gold nanoparticle arrays by incorporating the gold precursor into the P2VP chains. The combination of nanostructures prepared from block copolymer micellar arrays and macrostructures induced by incompatibility between the copolymer and the homopolymer leads to the formation of complex, multi-scale surface patterns by a simple casting process.A simple, straightforward process for fabricating multi-scale micro- and nanostructured patterns from polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP)/poly(methyl methacrylate) (PMMA) homopolymer in a preferential solvent for PS and PMMA is demonstrated. When the PS-b-P2VP/PMMA blend films were spin-coated onto a silicon wafer, PS-b-P2VP micellar arrays consisting of a PS corona and a P2VP core were formed, while the PMMA macrodomains were isolated, due to the macrophase separation caused by the incompatibility between block copolymer micelles and PMMA homopolymer during the spin-coating process. With an increase of PMMA composition, the size of PMMA macrodomains increased. Moreover, the P2VP blocks have a strong interaction with a native oxide of the surface of the silicon wafer, so that the P2VP wetting layer was first formed during spin-coating, and PS nanoclusters were observed on the PMMA macrodomains beneath. Whereas when a silicon surface was modified with a PS brush layer, the PS nanoclusters underlying PMMA domains were not formed. The multi-scale patterns prepared from copolymer micelle/homopolymer blend films are used as templates for the fabrication of gold nanoparticle arrays by incorporating the gold precursor into the P2VP chains. The combination of nanostructures prepared from block copolymer micellar arrays and macrostructures induced by incompatibility between the copolymer and the homopolymer leads to the formation of complex, multi-scale surface patterns by a simple casting process. Electronic supplementary information (ESI) available: AFM images of PS-b-P2VP/PMMA blend films and cross-sectional line scans. See DOI: 10.1039/c2nr11792d

Fabrication of Refractive Index Tunable Coating with Moisture-Resistant Function for High-Power Laser Systems Based on Homogeneous Embedding of Surface-Modified Nanoparticles.

PubMed

Yang, Wei; Lei, Xiangyang; Hui, Haohao; Zhang, Qinghua; Deng, Xueran

2018-05-07

Moisture-resistant silicone coatings were prepared on the surface of potassium dihydrogen phosphate (KDP) crystal by means of spin-coating, in which hydrophobic-modified SiO₂ nanoparticles were embedded in a certain proportion. The refractive index of such coating can be tuned arbitrarily in the range of 1.21⁻1.44, which endows the KDP optical component with excellent transmission capability as well as the moisture proof effect. A dual-layer anti-reflective coating system was obtained by covering this silicone coating with a porous SiO₂ coating which is specially treated to enhance the moisture resistance. Transmittance of such a dual-layer coating system could reach 99.60% and 99.62% at 1064 nm and 532 nm, respectively, by precisely matching the refractive index of both layers. Furthermore, the long-term stability of this coating system has been verified at high humidity ambient of 80% RH for 27 weeks.

Glass-wool study of laser-induced spin currents en route to hyperpolarized Cs salt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishikawa, Kiyoshi

2011-07-15

The nuclear spin polarization of optically pumped Cs atoms flows to the surface of Cs hydride in a vapor cell. A fine glass wool lightly coated with the salt helps greatly increase the surface area in contact with the pumped atoms and enhance the spin polarization of the salt nuclei. Even though the glass wool randomly scatters the pump light, the atomic vapor can be polarized with unpolarized light in a magnetic field. The measured enhancement in the salt enables study of the polarizations of light and atomic nuclei very near the salt surface.

Fabrication of PVDF-TrFE based bilayered PbTiO3/PVDF-TrFE films capacitor

NASA Astrophysics Data System (ADS)

Nurbaya, Z.; Wahid, M. H.; Rozana, M. D.; Annuar, I.; Alrokayan, S. A. H.; Khan, H. A.; Rusop, M.

2016-07-01

Development of high performance capacitor is reaching towards new generation where the ferroelectric materials take places as the active dielectric layer. The motivation of this study is to produce high capacitance device with long life cycle. This was configured by preparing bilayered films where lead titanate as an active dielectric layer and stacked with the top dielectric layer, poly(vinyledenefluoride-trifluoroethylene). Both of them are being referred that have one in common which is ferroelectric behavior. Therefore the combination of ceramic and polymer ferroelectric material could perform optimum dielectric characteristic for capacitor applications. The fabrication was done by simple sol-gel spin coating method that being varied at spinning speed property for polymer layers, whereas maintaining the ceramic layer. The characterization of PVDF-TrFE/PbTiO3 was performed according to metal-insulator-metal stacked capacitor measurement which includes structural, dielectric, and ferroelectric measurement.

Fabrication of high-resolution nanostructures of complex geometry by the single-spot nanolithography method

PubMed Central

Anisimova, Margarita; Samardak, Aleksei; Ognev, Alexey

2015-01-01

Summary The paper presents a method for the high-resolution production of polymer nanopatterns with controllable geometrical parameters by means of a single-spot electron-beam lithography technique. The essence of the method entails the overexposure of a positive-tone resist, spin-coated onto a substrate where nanoscale spots are exposed to an electron beam with a dose greater than 0.1 pC per dot. A single-spot enables the fabrication of a nanoring, while a chain of spots placed at distance of 5–30 nm from each other allows the production of a polymer pattern of complex geometry of sub-10 nm resolution. We demonstrate that in addition to the naturally oxidized silicon substrates, gold-coated substrates can also successfully be used for the single-spot nanopattering technique. An explanation of the results related to the resist overexposure was demonstrated using Monte Carlo simulations. Our nanofabrication method significantly accelerates (up to 10 times) the fabrication rate as compared to conventional lithography on positive-tone resist. This technique can be potentially employed in the electronics industry for the production of nanoprinted lithography molds, etching masks, nanoelectronics, nanophotonics, NEMS and MEMS devices. PMID:25977869

Surface Nanostructures Formed by Phase Separation of Metal Salt-Polymer Nanocomposite Film for Anti-reflection and Super-hydrophobic Applications

NASA Astrophysics Data System (ADS)

Con, Celal; Cui, Bo

2017-12-01

This paper describes a simple and low-cost fabrication method for multi-functional nanostructures with outstanding anti-reflective and super-hydrophobic properties. Our method employed phase separation of a metal salt-polymer nanocomposite film that leads to nanoisland formation after etching away the polymer matrix, and the metal salt island can then be utilized as a hard mask for dry etching the substrate or sublayer. Compared to many other methods for patterning metallic hard mask structures, such as the popular lift-off method, our approach involves only spin coating and thermal annealing, thus is more cost-efficient. Metal salts including aluminum nitrate nonahydrate (ANN) and chromium nitrate nonahydrate (CNN) can both be used, and high aspect ratio (1:30) and high-resolution (sub-50 nm) pillars etched into silicon can be achieved readily. With further control of the etching profile by adjusting the dry etching parameters, cone-like silicon structure with reflectivity in the visible region down to a remarkably low value of 2% was achieved. Lastly, by coating a hydrophobic surfactant layer, the pillar array demonstrated a super-hydrophobic property with an exceptionally high water contact angle of up to 165.7°.

Surface Nanostructures Formed by Phase Separation of Metal Salt-Polymer Nanocomposite Film for Anti-reflection and Super-hydrophobic Applications.

PubMed

Con, Celal; Cui, Bo

2017-12-16

This paper describes a simple and low-cost fabrication method for multi-functional nanostructures with outstanding anti-reflective and super-hydrophobic properties. Our method employed phase separation of a metal salt-polymer nanocomposite film that leads to nanoisland formation after etching away the polymer matrix, and the metal salt island can then be utilized as a hard mask for dry etching the substrate or sublayer. Compared to many other methods for patterning metallic hard mask structures, such as the popular lift-off method, our approach involves only spin coating and thermal annealing, thus is more cost-efficient. Metal salts including aluminum nitrate nonahydrate (ANN) and chromium nitrate nonahydrate (CNN) can both be used, and high aspect ratio (1:30) and high-resolution (sub-50 nm) pillars etched into silicon can be achieved readily. With further control of the etching profile by adjusting the dry etching parameters, cone-like silicon structure with reflectivity in the visible region down to a remarkably low value of 2% was achieved. Lastly, by coating a hydrophobic surfactant layer, the pillar array demonstrated a super-hydrophobic property with an exceptionally high water contact angle of up to 165.7°.

Characteristics of TiO2/ZnO bilayer film towards pH sensitivity prepared by different spin coating deposition process

NASA Astrophysics Data System (ADS)

Rahman, Rohanieza Abdul; Zulkefle, Muhammad Al Hadi; Abdullah, Wan Fazlida Hanim; Rusop, M.; Herman, Sukreen Hana

2016-07-01

In this study, titanium dioxide (TiO2) and zinc oxide (ZnO) bilayer film for pH sensing application will be presented. TiO2/ZnO bilayer film with different speed of spin-coating process was deposited on Indium Tin Oxide (ITO), prepared by sol-gel method. This fabricated bilayer film was used as sensing membrane for Extended Gate Field-Effect Transistor (EGFET) for pH sensing application. Experimental results indicated that the sensor is able to detect the sensitivity towards pH buffer solution. In order to obtained the result, sensitivity measurement was done by using the EGFET setup equipment with constant-current (100 µA) and constant-voltage (0.3 V) biasing interfacing circuit. TiO2/ZnO bilayer film which the working electrode, act as the pH-sensitive membrane was connected to a commercial metal-oxide semiconductor FET (MOSFET). This MOSFET then was connected to the interfacing circuit. The sensitivity of the TiO2 thin film towards pH buffer solution was measured by dipping the sensing membrane in pH4, pH7 and pH10 buffer solution. These thin films were characterized by using Field Emission Scanning Electron Microscope (FESEM) to obtain the surface morphology of the composite bilayer films. In addition, I-V measurement was done in order to determine the electrical properties of the bilayer films. According to the result obtained in this experiment, bilayer film that spin at 4000 rpm, gave highest sensitivity which is 52.1 mV/pH. Relating the I-V characteristic of the thin films and sensitivity, the sensing membrane with higher conductivity gave better sensitivity.

Characterization of TiO2 films obtained by a wet chemical process

NASA Astrophysics Data System (ADS)

Sedik, Asma; Ferraria, Ana M.; Carapeto, Ana P.; Bellal, Bouzid; Trari, Mohamed; Outemzabet, Ratiba

2017-12-01

TiO2 has an easily tunable bandgap and a great absorption dye ability being widely used in many fields and in a number of fascinating applications. In this study, a wet chemical route, particularly a sol gel method using spin-coating is adopted to deposit TiO2 thin films onto soda lime glass and silicon substrates. TiO2 films were prepared by using an alcoholic solution of analytical reagent grade TiCl4 as titanium precursor at various experimental conditions. The accent was put on the conditions of preparation (spin time, spin speed, precursor concentration, number of coating layers etc), doping and on the post-deposit treatment namely the drying and the crystallization. The results showed a strong dependence on the drying temperature and on the temperature and duration of the crystallization. We found that the solution preparation and its color are important for getting a reproducible final product. The Raman spectra recorded at room temperature, showed the characteristic peaks of anatase which appear at 143 and around 396 cm-1. These peaks confirm the presence of TiO2. The X-ray diffraction (XRD) was used to identify the crystalline characteristic of TiO2 while the chemical states and relative amounts of the main elements existing in the samples were investigated by X-ray Photoelectron Spectroscopy (XPS). The morphology of the samples was visualized by AFM. We show by this work the feasibility to obtain different nanostructured TiO2 by changing the concentration of the solution. Photocatalytic activity of TiO2 films was evaluated. Rhodamine B is a recalcitrant dye and TiO2 was successfully tested for its oxidation. An abatement of 60% was obtained under sunlight for an initial concentration of 10 mg/l.

Characteristics of TiO{sub 2}/ZnO bilayer film towards pH sensitivity prepared by different spin coating deposition process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahman, Rohanieza Abdul, E-mail: rohanieza.abdrahman@gmail.com; Zulkefle, Muhammad Al Hadi, E-mail: alhadizulkefle@gmail.com; Abdullah, Wan Fazlida Hanim, E-mail: wanfaz@salam.uitm.edu.my

In this study, titanium dioxide (TiO{sub 2}) and zinc oxide (ZnO) bilayer film for pH sensing application will be presented. TiO{sub 2}/ZnO bilayer film with different speed of spin-coating process was deposited on Indium Tin Oxide (ITO), prepared by sol-gel method. This fabricated bilayer film was used as sensing membrane for Extended Gate Field-Effect Transistor (EGFET) for pH sensing application. Experimental results indicated that the sensor is able to detect the sensitivity towards pH buffer solution. In order to obtained the result, sensitivity measurement was done by using the EGFET setup equipment with constant-current (100 µA) and constant-voltage (0.3 V)more » biasing interfacing circuit. TiO{sub 2}/ZnO bilayer film which the working electrode, act as the pH-sensitive membrane was connected to a commercial metal-oxide semiconductor FET (MOSFET). This MOSFET then was connected to the interfacing circuit. The sensitivity of the TiO2 thin film towards pH buffer solution was measured by dipping the sensing membrane in pH4, pH7 and pH10 buffer solution. These thin films were characterized by using Field Emission Scanning Electron Microscope (FESEM) to obtain the surface morphology of the composite bilayer films. In addition, I-V measurement was done in order to determine the electrical properties of the bilayer films. According to the result obtained in this experiment, bilayer film that spin at 4000 rpm, gave highest sensitivity which is 52.1 mV/pH. Relating the I-V characteristic of the thin films and sensitivity, the sensing membrane with higher conductivity gave better sensitivity.« less

The optimization of CNT-PVA nanocomposite for mild steel coating: Effect of CNTs concentration on the corrosion rate of mild steel

NASA Astrophysics Data System (ADS)

Maryam, M.; Ibrahim, N. M. A. A.; Eswar, K. A.; Guliling, M.; Suhaimi, M. H. F.; Khusaimi, Z.; Abdullah, S.; Rusop, M.

2018-05-01

Carbon Nanotubes (CNTs) are molecular-scale tubes of graphitic carbon which have outstanding mechanical and magnetic properties with extraordinary strength. It can be said that CNTs can be used in coating application to prevent corrosion and lower the rate of corrosion on steel. However, CNT alone cannot be used for coating purposes. Therefore, by combining it with polymer to produce a nanocomposite thin film, it can be used for nanocoating on mild steel substrate. Polyvinyl alcohol (PVA) was chosen due to its high strength and high modulus polymer fibers and has the possibilities of improving the physicochemical properties of carbon nanotubes. Carbon nanotubes and polyvinyl alcohol (CNT-PVA) nanocomposite were prepared by using sol-gel method and coated as thin film on mild steel substrate by using spin coating. Sol-gel is a convenient technique used for the production of nanocomposite aqueous solution. Five samples were prepared at the different concentration of CNTs-PVA to verify the corrosion rate application. The samples were then characterized by Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) obtaining the structural properties, surface morphology and topography of samples. Raman spectroscopy was used to determine the microraman spectra of CNTs which showed the quality and purity of samples. Finally, corrosion test was done to measure the corrosion rate of samples at the different concentration of CNTs/PVA nanocomposite.

Surpassing 10% Efficiency Benchmark for Nonfullerene Organic Solar Cells by Scalable Coating in Air from Single Nonhalogenated Solvent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Long; Xiong, Yuan; Zhang, Qianqian

The commercialization of nonfullerene organic solar cells (OSCs) relies critically on the response under typical operating conditions (for instance, temperature, humidity) and the ability of scale-up. Despite the rapid increase in power conversion efficiency (PCE) of spin-coated devices fabricated in a protective atmosphere, the device efficiencies of printed nonfullerene OSC devices by blade-coating are still lower than 6%. This slow progress significantly limits the practical printing of high-performance nonfullerene OSCs. Here, a new and stable nonfullerene combination was introduced by pairing a commercially available nonfluorinated acceptor IT-M with the polymeric donor FTAZ. Over 12%-efficiency can be achieved in spincoated FTAZ:IT-Mmore » devices using a single halogen-free solvent. More importantly, chlorinefree, in air blade-coating of FTAZ:IT-M is able to yield a PCE of nearly 11%, despite a humidity of ~50%. X-ray scattering results reveal that large π-π coherence lengths, high degree of faceon orientation with respect to the substrate, and small domain spacings of ~20 nm are closely correlated with such high device performance. Our material system and approach yields the highest reported performance for nonfullerene OSC devices by a coating technique approximating scalable fabrication methods and holds great promise for the development of low-cost, low-toxicity, and high-efficiency OSCs by high-throughput production.« less

Biocompatible and Biomimetic Self-Assembly of Functional

DTIC Science & Technology

2007-10-03

rearrangement of the lipid/silica matrix to create a bio/nano interface quite similar to that formed by direct CDA. This approach has several advantages over CDA...precursors with a biologically compatible surfactant, glycerol monooleate ( GMO ) via dip-coating, spin-coating, drop-casting, or aerosol deposition...with water and remains in a semi-solid state. Upon exposure to UV/ozone, the GMO begins to photodecompose and the silanol precursors become more

A solid-state NMR method to determine domain sizes in multi-component polymer formulations

NASA Astrophysics Data System (ADS)

Schlagnitweit, Judith; Tang, Mingxue; Baias, Maria; Richardson, Sara; Schantz, Staffan; Emsley, Lyndon

2015-12-01

Polymer domain sizes are related to many of the physical properties of polymers. Here we present a solid-state NMR experiment that is capable of measuring domain sizes in multi-component mixtures. The method combines selective excitation of carbon magnetization to isolate a specific component with proton spin diffusion to report on domain size. We demonstrate the method in the context of controlled release formulations, which represents one of today's challenges in pharmaceutical science. We show that we can measure domain sizes of interest in the different components of industrial pharmaceutical formulations at natural isotopic abundance containing various (modified) cellulose derivatives, such as microcrystalline cellulose matrixes that are film-coated with a mixture of ethyl cellulose (EC) and hydroxypropyl cellulose (HPC).

Preparation of Plasmonic Platforms of Silver Wires on Gold Mirrors and Their Application to Surface Enhanced Fluorescence

PubMed Central

2015-01-01

In this report we describe a preparation of silver wires (SWs) on gold mirrors and its application to surface enhanced fluorescence (SEF) using a new methodology. Silica protected gold mirrors were drop-coated with a solution of silver triangular nanoprisms. The triangular nanoprisms were slowly air-dried to get silver wires that self-assembled on the gold mirrors. Fluorescence enhancement was studied using methyl azadioxatriangulenium chloride (Me-ADOTA·Cl) dye in PVA spin-coated on a clean glass coverslip. New Plasmonic Platforms (PPs) were assembled by placing a mirror with SWs in contact with a glass coverslip spin-coated with a uniform Me-ADOTA·Cl film. It was shown that surface enhanced fluorescence is a real phenomenon, not just an enhancement of the fluorescence signal due to an accumulation of the fluorophore on rough nanostructure surfaces. The average fluorescence enhancement was found to be about 15-fold. The lifetime of Me-ADOTA·Cl dye was significantly reduced (∼4 times) in the presence of SWs. Moreover, fluorescence enhancement and lifetime did not show any dependence on the excitation light polarization. PMID:25296293

Structural and electromagnetic properties of NiAlxFe2-xO4/SiO2 nanocomposite films deposited using a sol-gel spin-coating method

NASA Astrophysics Data System (ADS)

Wang, Li; Li, Xuejian; Li, Ji; Liu, Mei; Xu, Shichong; Li, Haibo

2017-12-01

NiAlxFe2-xO4/SiO2 (0 ≤ x ≤ 1.0) nanocomposite films deposited on Si(1 0 0) substrates were prepared by a sol-gel spin-coating method. The influences of Al3+ content and annealing temperature on the structural and electromagnetic properties of the nanocomposite films were investigated. The results indicated that NiAlxFe2-xO4 in the nanocomposite films crystallized after annealing at 1073 K and above. When the doping content x increased from 0 to 1.0, the lattice constants and the average crystallite sizes of the NiAlxFe2-xO4 nanoparticles decreased. The saturation magnetization and coercivity of the films were inversely proportional to the Al3+ content. The maximum value of saturation magnetization (361.6 emu/cm3) and the minimum value of coercivity (18.6 kA/m) were obtained for x of 0.2. When the annealing temperature increased from 1073 to 1473 K, the lattice constant and the average crystallite size of the NiAl0.2Fe1.8O4 nanoparticles increased from 0.8322 to 0.8349 nm and 4 to 28 nm, respectively, and the saturation magnetization and coercivity of the films increased from 214.8 to 464.5 emu/cm3 and 8.2 to 26.9 kA/m, respectively. Moreover, the DC resistivity of the films increased with increasing Al3+ content and annealing temperature.

Photovoltaic performance of textured silicon solar cells with MAPbBr3 perovskite nanophosphors to induce luminescent down-shifting

NASA Astrophysics Data System (ADS)

Ho, Wen-Jeng; Li, Guan-Yi; Liu, Jheng-Jie; Lin, Zong-Xian; You, Bang-Jin; Ho, Chun-Hung

2018-04-01

This study employed a two-step multi-cycle spin-coating method for the application of MAPbBr3 perovskite nanophosphors on textured silicon solar cells with the aim of enhancing photovoltaic performance through luminescent down-shifting (LDS). The surface morphology and dimensions of the MAPbBr3 perovskite nanophosphors were examined using scanning electron microscopy in conjunction with ImageJ software. The LDS effects of the nanophosphors were revealed by measuring photo-luminance, optical reflectance, and external quantum efficiency. The photovoltaic performance of cells with and without MAPbBr3 perovskite nanophosphors was evaluated according to photovoltaic current density-voltage (J-V) under AM 1.5 G solar illumination. Compared to uncoated cells, two-layer and one-layer coatings of MAPbBr3 perovskite nanophosphors were shown to enhance conversion efficiency by 4.56% and 3.38%, respectively.

Low temperature growth of ZnO nanorods array via solution-immersion on TiO2 seed layer

NASA Astrophysics Data System (ADS)

Asib, N. A. M.; Aadila, A.; Afaah, A. N.; Rusop, M.; Khusaimi, Z.

2018-05-01

In this work, TiO2:ZNR thin films were successfully fabricated on glass substrates at low temperatures of 75 to 90°C. The substrates were coated with titanium dioxide (TiO2) using sol-gel spin coating, which act as seed layer to grow zinc oxide nanorods (ZNR) by solution-immersion method. At 90 and 95° C, ZNR with hexagonal tip are well dispersed without any aggregation and exhibit more uniform nanorods array as observed using FESEM. The diffraction peak intensity of the (0 0 2)-plane increased as the temperature increased, indicating improved orientation in the c-axis direction of the ZNR as detected in XRD patterns. From UV-Vis absorbance spectra, it was found that the samples has higher absorption properties at middle range of immersion temperatures; 80, 85 and 90°C.

Bipolar resistive switching in graphene oxide based metal insulator metal structure for non-volatile memory applications

NASA Astrophysics Data System (ADS)

Singh, Rakesh; Kumar, Ravi; Kumar, Anil; Kashyap, Rajesh; Kumar, Mukesh; Kumar, Dinesh

2018-05-01

Graphene oxide based devices have attracted much attention recently because of their possible application in next generation electronic devices. In this study, bipolar resistive switching characteristics of graphene oxide based metal insulator metal structure were investigated for nonvolatile memories. The graphene oxide was prepared by the conventional Hummer's method and deposited on ITO coated glass by spin-coating technique. The dominant mechanism of resistive switching is the formation and rupture of the conductive filament inside the graphene oxide. The conduction mechanism for low and high resistance states are dominated by two mechanism the ohmic conduction and space charge limited current (SCLC) mechanism, respectively. Atomic Force Microscopy, X-ray diffraction, Cyclic-Voltammetry were conducted to observe the morphology, structure and behavior of the material. The fabricated device with Al/GO/ITO structure exhibited reliable bipolar resistive switching with set & reset voltage of -2.3 V and 3V respectively.

Preparation and transport properties of superconducting layers in the Ca-Sr-Bi-Cu-O system

NASA Astrophysics Data System (ADS)

Klee, M.; Stollman, G. M.; Stotz, S.; de Vries, J. W. C.

1988-08-01

Superconducting layers in the CaSrBiCuO system are prepared by thermal decomposition of metal carboxylates using a spin-coating and a dip-coating method onto ceramic MgO substrates. The samples consist of a tetragonal calcium-strontium-bismuth-cuprate and two bismuth-free calcium-strontium-cuprates. A step in the resistance versus temperature curve is observed which, together with the influence of magnetic fields, is interpreted as typical for a granular superconductor. The analysis shows that the critical current density is determined by domains of the order of some unit cells. The strong dependence of the superconducting transition on the orientation of an applied magnetic field is probably caused by the anisotropic layer structure. The coherence length perpendicular to the c-axis of the material is estimated to be ξab(0) = 4.0 nm and parallel to the c-axis ξc(0) = 0.6 nm.

Lanthanide-based NMR: a tool to investigate component distribution in mixed-monolayer-protected nanoparticles.

PubMed

Guarino, Gaetano; Rastrelli, Federico; Scrimin, Paolo; Mancin, Fabrizio

2012-05-02

Gd(3+) ions, once bound to the monolayer of organic molecules coating the surface of gold nanoparticles, produce a paramagnetic relaxation enhancement (PRE) that broadens and eventually cancels the signals of the nuclear spins located nearby (within 1.6 nm distance). In the case of nanoparticles coated with mixed monolayers, the signals arising from the different coating molecules experience different PRE, depending on their distance from the binding site. As a consequence, observation of the signal broadening patterns provides direct information on the monolayer organization. © 2012 American Chemical Society

Chitosan-silane sol-gel hybrid thin films with controllable layer thickness and morphology.

PubMed

Spirk, Stefan; Findenig, Gerald; Doliska, Ales; Reichel, Victoria E; Swanson, Nicole L; Kargl, Rupert; Ribitsch, Volker; Stana-Kleinschek, Karin

2013-03-01

The preparation of thin films of chitosan-silane hybrid materials by combining sol-gel processing and spin coating is reported. A variety of silanes can be used as starting materials for the preparation of such thin films, namely tetraethoxysilane, tri-tert-butoxysilanol, trimethylethoxysilane, p-trifluoromethyltetra-fluorophenyltriethoxysilane, trivinylmethoxysilane, (methoxymethyl)trimethyl-silane, and hexamethoxydisilane. These silanes are subjected to a sol-gel process before they are added to acidic chitosan solutions. The chitosan:silane ratio is kept constant at 6:1 (w/w) and dilutions with ethanol are prepared and spin coated. Depending on the degree of dilution, film thickness can be controlled in a range between 5 and 70 nm. For the determination of additional surface properties, static water contact angle measurements and atomic force microscopy have been employed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Fabrication and characterization of high mobility spin-coated zinc oxide thin film transistors

NASA Astrophysics Data System (ADS)

Singh, Shaivalini; Chakrabarti, P.

2012-10-01

A ZnO based thin film transistor (TFT) with bottom-gate configuration and SiO2 as insulating layer has been fabricated and characterized. The ZnO thin film was prepared by spin coating the sol-gel solution on the p-type Si wafers. The optical and structural properties of ZnO films were investigated using UV measurements and scanning electron microscope (SEM). The result of UV-visible study confirms that the films have a good absorbance in UV region and relatively low absorbance in the visible region. The TFT exhibited an off-current of 2.5×10-7 A. The values of field effect channel mobility and on/off current ratio extracted for the device, measured 11 cm2/V.s and ~102 respectively. The value of threshold voltage was found to be 1.3 V.

Non-blinking single-photon emitters in silica

DOE PAGES

Rabouw, Freddy T.; Cogan, Nicole M. B.; Berends, Anne C.; ...

2016-02-19

Samples for single-emitter spectroscopy are usually prepared by spin-coating a dilute solution of emitters on a microscope cover slip of silicate based glass (such as quartz). Here, we show that both borosilicate glass and quartz contain intrinsic defect colour centres that fluoresce when excited at 532 nm. In a microscope image the defect emission is indistinguishable from spin-coated emitters. The emission spectrum is characterised by multiple peaks with the main peak between 2.05 and 2.20 eV, most likely due to coupling to a silica vibration with an energy that varies between 160 and 180 meV. The defects are single-photon emitters,more » do not blink, and have photoluminescence lifetimes of a few nanoseconds. Furthermore, photoluminescence from such defects may previously have been misinterpreted as originating from single nanocrystal quantum dots.« less

Direct formation of InN-codoped p-ZnO/n-GaN heterojunction diode by solgel spin-coating scheme.

PubMed

Huang, Chun-Ying; Lee, Ya-Ju; Lin, Tai-Yuan; Chang, Shao-Lun; Lian, Jan-Tian; Lin, Hsiu-Mei; Chen, Nie-Chuan; Yang, Ying-Jay

2014-02-15

In this work p-ZnO/n-GaN heterojunction diodes were directly formed on the Si substrate by a combination of cost-effective solgel spin-coating and thermal annealing treatment. Spin-coated n-ZnO films on InN/GaN/Si wafers were converted to p-type polarity after thermal treatment of proper annealing durations. X-ray diffraction (XRD) analysis reveals that InN-codoped ZnO films have grown as the standard hexagonal wurtzite structure with a preferential orientation in the (002) direction. The intensity of the (002) peak decreases for a further extended annealing duration, indicating the greater incorporation of dopants, also confirmed by x-ray photoelectron spectroscopy and low-temperature photoluminescence. Hall and resistivity measurements validate that our p-type ZnO film has a high carrier concentration of 3.73×10¹⁷ cm⁻³, a high mobility of 210 cm²/Vs, and a low resistivity of 0.079 Ωcm. As a result, the proposed p-ZnO/n-GaN heterojunction diode displays a well-behaving current rectification of a typical p-n junction, and the measured current versus voltage (I-V) characteristic is hence well described by the modified Shockley equation. The research on the fabrication of p-ZnO/n-GaN heterojunctions shown here generates useful advances in the production of cost-effective ZnO-based optoelectronic devices.

Novel Silicone-Coated 125I Seeds for the Treatment of Extrahepatic Cholangiocarcinoma

PubMed Central

Zhang, Weixing; Cai, Xiaobo; Chen, Dafan; Wan, Xinjian

2016-01-01

125I seeds coated with titanium are considered a safe and effective interstitial brachytherapy for tumors, while the cost of 125I seeds is a major problem for the patients implanting lots of seeds. The aim of this paper was to develop a novel silicone coating for 125I seeds with a lower cost. In order to show the radionuclide utilization ratio, the silicone was coated onto the seeds using the electro-spinning method and the radioactivity was evaluated, then the anti-tumor efficacy of silicone 125I seeds was compared with titanium 125I seeds. The seeds were divided into four groups: A (control), B (pure silicone), C (silicone 125I), D (titanium 125I) at 2 Gy or 4 Gy. Their anti-tumour activity and mechanism were assessed in vitro and in vivo using a human extrahepatic cholangiocarcinoma cell line FRH-0201 and tumor-bearing BALB/c nude mice. The silicone 125I seeds showed higher radioactivity; the rate of cell apoptosis in vitro and the histopathology in vivo demonstrated that the silicone 125I seeds shared similar anti-tumor efficacy with the titanium 125I seeds for the treatment of extrahepatic cholangiocarcinoma, while they have a much lower cost. PMID:26840346

Photoreactive elastin-like proteins for use as versatile bioactive materials and surface coatings

PubMed Central

Raphel, Jordan; Parisi-Amon, Andreina; Heilshorn, Sarah

2012-01-01

Photocrosslinkable, protein-engineered biomaterials combine a rapid, controllable, cytocompatible crosslinking method with a modular design strategy to create a new family of bioactive materials. These materials have a wide range of biomedical applications, including the development of bioactive implant coatings, drug delivery vehicles, and tissue engineering scaffolds. We present the successful functionalization of a bioactive elastin-like protein with photoreactive diazirine moieties. Scalable synthesis is achieved using a standard recombinant protein expression host followed by site-specific modification of lysine residues with a heterobifunctional N-hydroxysuccinimide ester-diazirine crosslinker. The resulting biomaterial is demonstrated to be processable by spin coating, drop casting, soft lithographic patterning, and mold casting to fabricate a variety of two- and three-dimensional photocrosslinked biomaterials with length scales spanning the nanometer to millimeter range. Protein thin films proved to be highly stable over a three-week period. Cell-adhesive functional domains incorporated into the engineered protein materials were shown to remain active post-photo-processing. Human adipose-derived stem cells achieved faster rates of cell adhesion and larger spread areas on thin films of the engineered protein compared to control substrates. The ease and scalability of material production, processing versatility, and modular bioactive functionality make this recombinantly engineered protein an ideal candidate for the development of novel biomaterial coatings, films, and scaffolds. PMID:23015764

Photoreactive elastin-like proteins for use as versatile bioactive materials and surface coatings.

PubMed

Raphel, Jordan; Parisi-Amon, Andreina; Heilshorn, Sarah

2012-10-07

Photocrosslinkable, protein-engineered biomaterials combine a rapid, controllable, cytocompatible crosslinking method with a modular design strategy to create a new family of bioactive materials. These materials have a wide range of biomedical applications, including the development of bioactive implant coatings, drug delivery vehicles, and tissue engineering scaffolds. We present the successful functionalization of a bioactive elastin-like protein with photoreactive diazirine moieties. Scalable synthesis is achieved using a standard recombinant protein expression host followed by site-specific modification of lysine residues with a heterobifunctional N-hydroxysuccinimide ester-diazirine crosslinker. The resulting biomaterial is demonstrated to be processable by spin coating, drop casting, soft lithographic patterning, and mold casting to fabricate a variety of two- and three-dimensional photocrosslinked biomaterials with length scales spanning the nanometer to millimeter range. Protein thin films proved to be highly stable over a three-week period. Cell-adhesive functional domains incorporated into the engineered protein materials were shown to remain active post-photo-processing. Human adipose-derived stem cells achieved faster rates of cell adhesion and larger spread areas on thin films of the engineered protein compared to control substrates. The ease and scalability of material production, processing versatility, and modular bioactive functionality make this recombinantly engineered protein an ideal candidate for the development of novel biomaterial coatings, films, and scaffolds.

Seesaw-like polarized transmission behavior of silver nanowire arrays aligned by off-center spin-coating

NASA Astrophysics Data System (ADS)

Kang, Lu; Chen, Hui; Yang, Zhong-Jian; Yuan, Yongbo; Huang, Han; Yang, Bingchu; Gao, Yongli; Zhou, Conghua

2018-05-01

Straight silver nanowires were synthesized by accelerated oxidization and then aligned into ordered arrays by off-center spin-coating. Seesaw-like behavior was observed in the polarized transmission spectra of the arrays. With the increment of polarization angle (θP, defined as the angle between axis of nanowires and direction of electric field of light), transmission changed repeatedly with a period of 180°, but it moved to opposite directions between the two regions separated by supporting points locating at 494 nm. The behavior is ascribed to the competition between the extinction behaviors of the two modes of surface plasma polaritons on silver nanowires. One is the longitudinal mode which is excited by long wavelengths and tuned by function of cos2( θ p ) and the other is the transverse mode that is excited by short wavelengths and tuned by function of sin2( θ p ). Simulation was performed based on the finite-difference time domain method. The effect of the nanowire diameter and length (aspect ratio) on the position of the supporting point was studied. As nanowire width increased from 20 nm to 350 nm, the supporting point moved from 400 to 500 nm. While it changed slightly when the nanowire length increased from 3 μm to infinitely long (width fixed at 260 nm). In current study, the position of the supporting point is mainly determined by the nanowire width.

Thickness Dependent Structural and Dielectric Properties of Calcium Copper Titanate Thin Films Produced by Spin-Coating Method for Microelectronic Devices

NASA Astrophysics Data System (ADS)

Thiruramanathan, P.; Sankar, S.; Marikani, A.; Madhavan, D.; Sharma, Sanjeev K.

2017-07-01

Calcium copper titanate (CaCu3Ti4O12, CCTO) thin films have been deposited on platinized silicon [(111)Pt/Ti/SiO2/Si] substrate through a sol-gel spin coating technique and annealed at 600-900°C with a variation of 100°C per sample for 3 h. The activation energy for crystalline growth, as well as optimal annealing temperature (900°C) of the CCTO crystallites was studied by x-ray diffraction analysis (XRD). Thickness dependent structural, morphological, and optical properties of CCTO thin films were observed. The field emission scanning electron microscopy (FE-SEM) verified that the CCTO thin films are uniform, fully covered, densely packed, and the particle size was found to be increased with film thickness. Meanwhile, quantitative analysis of dielectric properties (interfacial capacitance, dead layers, and bulk dielectric constant) of CCTO thin film with metal-insulator-metal (M-I-M) structures has been investigated systematically using a series capacitor model. Room temperature dielectric properties of all the samples exhibit dispersion at low frequencies, which can be explained based on Maxwell-Wagner two-layer models and Koop's theory. It was found that the 483 nm thick CCTO film represents a high dielectric constant ( ɛ r = 3334), low loss (tan δ = 3.54), capacitance ( C = 4951 nF), which might satisfy the requirements of embedded capacitor.

The photovoltaic efficiency of the fabrication of copolymer P3HT:PCBM on different thickness nano-anatase titania as solar cell.

PubMed

Lazim, Haidar Gazy; Ajeel, Khalid I; Badran, Hussain A

2015-06-15

Organic solar cells based on (3-hexylthiophene):[6,6]-phenyl C61-butyric acid methylester (P3HT:PCBM) bulk heterojunction (BHJ) with an inverted structure have been fabricated using nano-anatase crystalline titanium dioxide (TiO2) as their electron transport layer, which was prepared on the indium tin oxide coated glass (ITO-glass), silicon wafer and glass substrates by sol-gel method at different spin speed by using spin-coating (1000, 2000 and 3,000 rpm) for nano-thin film 58, 75 and 90 nm respectively. The effect of thickness on the surface morphology and optical properties of TiO2 layer were investigated by atomic force microscopy (AFM), X-ray diffraction and UV-visible spectrophotometer. The optical band gap of the films has been found to be in the range 3.63-3.96 eV for allowed direct transition and to be in the range 3.23-3.69 eV for forbidden direct transition to the different TiO2 thickness. The samples were examined to feature current and voltages darkness and light extraction efficiency of the solar cell where they were getting the highest open-circuit voltage, Voc, and power conversion efficiency were 0.66% and 0.39% fabricated with 90 nm respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Studies on visible light photocatalytic and antibacterial activities of nanostructured cobalt doped ZnO thin films prepared by sol-gel spin coating method.

PubMed

Poongodi, G; Anandan, P; Kumar, R Mohan; Jayavel, R

2015-09-05

Nanostructured cobalt doped ZnO thin films were deposited on glass substrate by sol-gel spin coating technique and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and UV-Vis spectroscopy. The XRD results showed that the thin films were well crystalline with hexagonal wurtzite structure. The results of EDAX and XPS revealed that Co was doped into ZnO structure. FESEM images revealed that the films possess granular morphology without any crack and confirm that Co doping decreases the grain size. UV-Vis transmission spectra show that the substitution of Co in ZnO leads to band gap narrowing. The Co doped ZnO films were found to exhibit improved photocatalytic activity for the degradation of methylene blue dye under visible light in comparison with the undoped ZnO film. The decrease in grain size and extending light absorption towards the visible region by Co doping in ZnO film contribute equally to the improved photocatalytic activity. The bactericidal efficiency of Co doped ZnO films were investigated against a Gram negative (Escherichia coli) and a Gram positive (Staphylococcus aureus) bacteria. The optical density (OD) measurement showed better bactericidal activity at higher level of Co doping in ZnO. Copyright © 2015 Elsevier B.V. All rights reserved.

Development of a Biosensor Nanofluidic Platform for Integration with Terahertz Spectroscopic System

DTIC Science & Technology

2014-06-27

space. The instrumentation for fabrication of micro/nano-fluidic chips including a Laser-Cutting System, a Sputtering system, a Spin Coating ...polyester (PET) substrate, as PET is more chemically and thermally resistant, and can be readily obtained in a variety of thicknesses down to 12.5 um...to create the array pattern on the silver coated PET substrate. Copper was then electrodeposited to a thickness of 5 um around the photoresist

Niobium superconducting rf cavity fabrication by electrohydraulic forming

NASA Astrophysics Data System (ADS)

Cantergiani, E.; Atieh, S.; Léaux, F.; Perez Fontenla, A. T.; Prunet, S.; Dufay-Chanat, L.; Koettig, T.; Bertinelli, F.; Capatina, O.; Favre, G.; Gerigk, F.; Jeanson, A. C.; Fuzeau, J.; Avrillaud, G.; Alleman, D.; Bonafe, J.; Marty, P.

2016-11-01

Superconducting rf (SRF) cavities are traditionally fabricated from superconducting material sheets or made of copper coated with superconducting material, followed by trim machining and electron-beam welding. An alternative technique to traditional shaping methods, such as deep-drawing and spinning, is electrohydraulic forming (EHF). In EHF, half-cells are obtained through ultrahigh-speed deformation of blank sheets, using shockwaves induced in water by a pulsed electrical discharge. With respect to traditional methods, such a highly dynamic process can yield interesting results in terms of effectiveness, repeatability, final shape precision, higher formability, and reduced springback. In this paper, the first results of EHF on high purity niobium are presented and discussed. The simulations performed in order to master the multiphysics phenomena of EHF and to adjust its process parameters are presented. The microstructures of niobium half-cells produced by EHF and by spinning have been compared in terms of damage created in the material during the forming operation. The damage was assessed through hardness measurements, residual resistivity ratio (RRR) measurements, and electron backscattered diffraction analyses. It was found that EHF does not worsen the damage of the material during forming and instead, some areas of the half-cell have shown lower damage compared to spinning. Moreover, EHF is particularly advantageous to reduce the forming time, preserve roughness, and to meet the final required shape accuracy.

Thermally stimulated nonlinear refraction in gelatin stabilized Cu-PVP nanocomposite thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamgadge, Y. S., E-mail: ystamgadge@gmail.com; Atkare, D. V.; Pahurkar, V. G.

2016-05-06

This article illustrates investigations on thermally stimulated third order nonlinear refraction of Cu-PVP nanocomposite thin films. Cu nanoparticles have been synthesized using chemical reduction method and thin films in PVP matrix have been obtained using spin coating technique. Thin films have been characterized by X-ray diffraction (XRD) and Ultraviolet-visible (UV-vis) spectroscopyfor structural and linear optical studies. Third order nonlinear refraction studies have been performed using closed aperture z-scan technique under continuous wave (CW) He-Ne laser. Cu-PVP nanocomposites are found to exhibit strong nonlinear refractive index stimulated by thermal lensing effect.

Cr:SnO2 thin films-synthesis and characterization

NASA Astrophysics Data System (ADS)

Varghese, Anitta Rose; B. Bhadrapriya, C.; Amarendra, G.; Hussain, Shamima

2018-04-01

Thin films of pure and Chromium doped SnO2 were synthesized using sol-gel method by spin coating technique. XRD studies confirmed the formation of tetragonal structure for SnO2 thin films. Variations in peak width and position were identified with doping. The optical band gap of the undoped films was found to be 3.8eV and varied with doping. Raman spectrum gave signature peaks of Sn-O and Cr-O bonds for undoped and doped films. The uniformity of the samples and formation of aggregates were observed from FESEM analysis.

Solvent influence upon structure & throughput of poly vinyledene fluoride thin film nano-patterns by imprint lithography

NASA Astrophysics Data System (ADS)

Sankar, M. S. Ravi; Gangineni, R. B.

2018-04-01

This work aims at understanding the solvent influence upon the throughput and structure of poly vinyledene fluoride (PVDF)nano-patterned films. The PVDF thin films are deposited by spin coating method using Dimethylsulfoxide (DMSO), Tetrahydrofuran (THF) and 2-butanone solvents. The nano-patterns are realized by imprinting SONY 700 MB CD aluminum constructions on PVDF thin filmsusing imprint lithography technique under ambient annealing temperature and pressure. Surface morphology &imprint pattern transfer quality is evaluated with Atomic force microscopy (AFM). Raman spectroscopy is used for evaluating the structural evolutions with respect to solvent & patterning.

Electrochemical and fluorescence properties of SnO2 thin films and its antibacterial activity

NASA Astrophysics Data System (ADS)

Henry, J.; Mohanraj, K.; Sivakumar, G.; Umamaheswari, S.

2015-05-01

Nanocrystalline SnO2 thin films were deposited by a simple and inexpensive sol-gel spin coating technique and the films were annealed at two different temperatures (350 °C and 450 °C). Structural, vibrational, optical and electrochemical properties of the films were analyzed using XRD, FTIR, UV-Visible, fluorescence and cyclic voltammetry techniques respectively and their results are discussed in detail. The antimicrobial properties of SnO2 thin films were investigated by agar agar method and the results confirm the antibacterial activity of SnO2 against Escherichia coli and Bacillus.

Synthesis of cobalt doped BiFeO3 multiferroic thin films on p-Si substrate by sol-gel method

NASA Astrophysics Data System (ADS)

Prasannakumara, R.; Shrisha, B. V.; Naik, K. Gopalakrishna

2018-05-01

Bismuth ferrite (BiFeO3) and cobalt doped BiFeO3 (BiFe1-xCoxO3) nanostructure thin films were grown on p-silicon substrates by sol-gel spin coating method with a sequence of coating and annealing process. The post-annealing of the grown films was carried out under high pure argon atmosphere. The grown nanostructure thin films were characterized using XRD, FESEM, and AFM for the structural, morphological and topological studies, respectively. The elemental compositions of the samples were studied by EDX spectra. The PL spectra of the grown sample shows a narrow emission peak around 559 nm which corresponds to the energy band gap of BFO thin films. The XRD peaks of the BiFeO3 nanostructure thin film reveals the rhombohedral structure and transformed from rhombohedral to orthorhombic or tetragonal structure in Co doped BiFeO3 thin films. The Co substitution in BiFeO3 helped to obtain higher dense nanostructure thin films with smaller grain size than the BiFeO3 thin films.

Initial Study on Thin Film Preparation of Carbon Nanodots Composites as Luminescence Material

NASA Astrophysics Data System (ADS)

Iskandar, F.; Aimon, A. H.; Akmaluddin, A. R.; Nuryadin, B. W.; Abdullah, M.

2016-08-01

Nowadays, the developments of phosphors materials require elements without noble metals and simple production process. Carbon nanodots (C-dots) are one of phosphor materials with wide range of emission band, and high biocompatibility. In this research thin film carbon nanodots composite have been prepared by spin coating method. Prior deposition, powder carbon nanodots were synthesized from a mixture of commercial urea as the nitrogen sources and citric acid as a carbon source by using hydrothermal and microwave-assisted heating method. The prepared powder was dispersed in transparent epoxy resin and then coated on glass substrate. The photoluminescence result for sample with 0.035 g citric acid exhibited an intense, single, homogeneous and broad spectrum with yellowish emission upon excitation at 365 nm. The Fourier Transform Infrared Spectroscopy (FTIR) result showed the existences of C=C, C-H, C=O, N-H and O-H functional groups which confirmed the quality of the sample. Further, based on UV-Vis measurement, the prepared thin film was highly transparent (transmittance 90%) with estimated film thickness around 764 nm. This result may open an opportunity for optoelectronic devices.

In vitro degradation and release characteristics of spin coated thin films of PLGA with a “breath figure” morphology

PubMed Central

Ponnusamy, Thiruselvam; Lawson, Louise B.; Freytag, Lucy C.; Blake, Diane A.; Ayyala, Ramesh S.; John, Vijay T.

2012-01-01

Poly (lactic-co-glycolic acid) (PLGA) coatings on implant materials are widely used in controlled drug delivery applications. Typically, such coatings are made with non-porous films. Here, we have synthesized a thin PLGA film coating with a highly ordered microporous structure using a simple and inexpensive water templating “breath figure” technique. A single stage process combining spin coating and breath figure process was used to obtain drug incorporated porous thin films. The films were characterized by scanning electron microscope (SEM) to observe the surface and bulk features of porosity and also, degradation pattern of the films. Moreover, the effect of addition of small amount of poly (ethylene glycol) (PEG) into PLGA was characterized. SEM analysis revealed an ordered array of ~2 µm sized pores on the surface with the average film thickness measured to be 20 µm. The incorporation of hydrophilic poly (ethylene glycol) (PEG) enhances pore structure uniformity and facilitates ingress of water into the structure. A five week in vitro degradation study showed a gradual deterioration of the breath figure pores. During the course of degradation, the surface pore structure deteriorates to initially flatten the surface. This is followed by the formation of new pinprick pores that eventually grow into a macroporous film prior to film breakup. Salicylic acid (highly water soluble) and Ibuprofen (sparingly water soluble) were chosen as model drug compounds to characterize release rates, which are higher in films of the breath figure morphology rather than in non-porous films. The results are of significance in the design of biodegradable films used as coatings to modulate delivery. PMID:23507805

Fortifying the Bone-Implant Interface Part 1: An In Vitro Evaluation of 3D-Printed and TPS Porous Surfaces

PubMed Central

Lindsey, Derek P.; Bahney, Chelsea S.; Woods, Shane A.; Wolfe, Mark L.; Yerby, Scott A.

2017-01-01

Background An aging society and concomitant rise in the incidence of impaired bone health have led to the need for advanced osteoconductive spinal implant surfaces that promote greater biological fixation (e.g. for interbody fusion cages, sacroiliac joint fusion implants, and artificial disc replacements). Additive manufacturing, i.e. 3D-printing, may improve bone integration by generating biomimetic spinal implant surfaces that mimic bone morphology. Such surfaces may foster an enhanced cellular response compared to traditional implant surfacing processes. Methods This study investigated the response of human osteoblasts to additive manufactured (AM) trabecular-like titanium implant surfaces compared to traditionally machined base material with titanium plasma spray (TPS) coated surfaces, with and without a nanocrystalline hydroxyapatite (HA) coating. For TPS-coated discs, wrought Ti6Al4V ELI was machined and TPS-coating was applied. For AM discs, Ti6Al4V ELI powder was 3D-printed to form a solid base and trabecular-like porous surface. The HA-coating was applied via a precipitation dip-spin method. Surface porosity, pore size, thickness, and hydrophilicity were characterized. Initial cell attachment, proliferation, alkaline phosphatase (ALP) activity, and calcium production of hFOB cells (n=5 per group) were measured. Results Cells on AM discs exhibited expedited proliferative activity. While there were no differences in mean ALP expression and calcium production between TPS and AM discs, calcium production on the AM discs trended 48% higher than on TPS discs (p=0.07). Overall, HA-coating did not further enhance results compared to uncoated TPS and AM discs. Conclusions Results demonstrate that additive manufacturing allows for controlled trabecular-like surfaces that promote earlier cell proliferation and trends toward higher calcium production than TPS coating. Results further showed that nanocrystalline HA may not provide an advantage on porous titanium surfaces. Clinical Relevance Additive manufactured porous titanium surfaces may induce a more osteogenic environment compared to traditional TPS, and thus present as an attractive alternative to TPS-coating for orthopedic spinal implants. PMID:28765799

Polymeric Coatings for Combating Biocorrosion

NASA Astrophysics Data System (ADS)

Guo, Jing; Yuan, Shaojun; Jiang, Wei; Lv, Li; Liang, Bin; Pehkonen, Simo O.

2018-03-01

Biocorrosion has been considered as big trouble in many industries and marine environments due to causing great economic loss. The main disadvantages of present approaches to prevent corrosion include being limited by environmental factors, being expensive, inapplicable to field, and sometimes inefficient. Studies show that polymer coatings with anti-corrosion and anti-microbial properties have been widely accepted as a novel and effective approach to preventbiocorrosion. The main purpose of this review is to summarize up the progressive status of polymer coatings used for combating microbially-induced corrosion. Polymers used to synthesize protective coatings are generally divided into three categories: i) traditional polymers incorporated with biocides, ii) antibacterial polymers containing quaternary ammonium compounds, and iii) conductive polymers. The strategies to synthesize polymer coatings resort mainly to grafting anti-bacterial polymers from the metal substrate surface using novel surface-functionalization approaches, such as free radical polymerization, chemically oxidative polymerization and surface-initiated atom transfer radical polymerization, as opposed to the traditional approaches of dip coating or spin coating.

Influence of biodegradable polymer coatings on corrosion, cytocompatibility and cell functionality of Mg-2.0Zn-0.98Mn magnesium alloy.

PubMed

Witecka, Agnieszka; Yamamoto, Akiko; Idaszek, Joanna; Chlanda, Adrian; Święszkowski, Wojciech

2016-08-01

Four kinds of biodegradable polymers were employed to prepare bioresorbable coatings on Mg-2.0Zn-0.98Mn (ZM21) alloy to understand the relationship between polymer characteristics, protective effects on substrate corrosion, cytocompatibility and cell functionality. Poly-l-lactide (PLLA), poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) or poly(lactic-co-glycolic) acid (PLGA) was spin-coated on ZM21, obtaining a smooth, non-porous coating less than 0.5μm in thickness. Polymer coating characterization, a degradation study, and biocompatibility evaluations were performed. After 4 w of immersion into cell culture medium, degradation of PLGA and PLLA coatings were confirmed by ATR-FTIR observation. The coatings of PLLA, PHB and PHBV, which have lower water permeability and slower degradation than PLGA, provide better suppression of initial ZM21 degradation and faster promotion of human osteosarcoma cell growth and differentiation. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication of multilayered thin films via spin-assembly

DOEpatents

Chiarelli, Peter A.; Robinson, Jeanne M.; Casson, Joanna L.; Johal, Malkiat S.; Wang, Hsing-Lin

2007-02-20

An process of forming multilayer thin film heterostructures is disclosed and includes applying a solution including a first water-soluble polymer from the group of polyanionic species, polycationic species and uncharged polymer species onto a substrate to form a first coating layer on the substrate, drying the first coating layer on the substrate, applying a solution including a second water-soluble polymer from the group of polyanionic species, polycationic species and uncharged polymer species onto the substrate having the first coating layer to form a second coating layer on the first coating layer wherein the second water-soluble polymer is of a different material than the first water-soluble polymer, and drying the second coating layer on the first coating layer so as to form a bilayer structure on the substrate. Optionally, one or more additional applying and drying sequences can be repeated with a water-soluble polymer from the group of polyanionic species, polycationic species and uncharged polymer species, so that a predetermined plurality of layers are built up upon the substrate.

Spin-Coating and Characterization of Multiferroic MFe{sub 2}O{sub 4} (M=Co, Ni) / BaTiO{sub 3} Bilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quandt, Norman; Roth, Robert; Syrowatka, Frank

2016-01-15

Bilayer films of MFe{sub 2}O{sub 4} (M=Co, Ni) and BaTiO{sub 3} were prepared by spin coating of N,N-dimethylformamide/acetic acid solutions on platinum coated silicon wafers. Five coating steps were applied to get the desired thickness of 150 nm for both the ferrite and perovskite layer. XRD, IR and Raman spectroscopy revealed the formation of phase-pure ferrite spinels and BaTiO{sub 3}. Smooth surfaces with roughnesses in the order of 3 to 5 nm were found in AFM investigations. Saturation magnetization of 347 emu cm{sup −3} for the CoFe{sub 2}O{sub 4}/BaTiO{sub 3} and 188 emu cm{sup −3} for the NiFe{sub 2}O{sub 4}/BaTiO{submore » 3} bilayer, respectively were found. For the CoFe{sub 2}O{sub 4}/BaTiO{sub 3} bilayer a strong magnetic anisotropy was observed with coercivity fields of 5.1 kOe and 3.3 kOe (applied magnetic field perpendicular and parallel to film surface), while for the NiFe{sub 2}O{sub 4}/BaTiO{sub 3} bilayer this effect is less pronounced. Saturated polarization hysteresis loops prove the presence of ferroelectricity in both systems. - Graphical abstract: The SEM image of the CoFe{sub 2}O{sub 4}/BaTiO{sub 3} bilayer on Pt–Si-substrate (left), magnetization as a function of the magnetic field perpendicular and parallel to the film plane (right top) and P–E and I–V hysteresis loops of the bilayer at room temperature. - Highlights: • Ferrite and perovskite oxides grown on platinum using spin coating technique. • Columnar growth of cobalt ferrite particle on the substrate. • Surface investigation showed a homogenous and smooth surface. • Perpendicular and parallel applied magnetic field revealed a magnetic anisotropy. • Switching peaks and saturated P–E hysteresis loops show ferroelectricity.« less

High color rendering index of remote-type white LEDs with multi-layered quantum dot-phosphor films and short-wavelength pass dichroic filters

NASA Astrophysics Data System (ADS)

Yoon, Hee Chang; Oh, Ji Hye; Do, Young Rag

2014-09-01

This paper introduces high color rendering index (CRI) white light-emitting diodes (W-LEDs) coated with red emitting (Sr,Ca)AlSiN3:Eu phosphors and yellowish-green emitting AgIn5S8/ZnS (AIS/ZS) quantum dots (QDs) on glass or a short-wavelength pass dichroic filter (SPDF), which transmit blue wavelength regions and reflect yellow wavelength regions. The red emitting (Sr,Ca)AlSiN3:Eu phosphor film is coated on glass and a SPDF using a screen printing method, and then the yellowish-green emitting AIS/ZS QDs are coated on the red phosphor (Sr,Ca)AlSiN3:Eu film-coated glass and SPDF using the electrospray (e-spray) method.To fabricate the red phosphor film, the optimum amount of phosphor is dispersed in a silicon binder to form a red phosphor paste. The AIS/ZS QDs are mixed with dimethylformamide (DMF), toluene, and poly(methyl methacrylate) (PMMA) for the e-spray coating. The substrates are spin-coated with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to fabricate a conductive surface. The CRI of the white LEDs is improved through inserting the red phosphor film between the QD layer and the glass substrate. Furthermore, the light intensities of the multi-layered phosphor films are enhanced through changing the glass substrate to the SPDF. The correlated color temperatures (CCTs) vary as a function of the phosphor concentration in the phosphor paste. The optical properties of the yellowish-green AIS/ZS QDs and red (Sr,Ca)AlSiN3:Eu phosphors are characterized using photoluminescence (PL), and the multi-layered QD-phosphor films are measured using electroluminescence (EL) with an InGaN blue LED (λmax = 450 nm) at 60 mA.

The Environmental Assessment and Management (TEAM) Guide: Delaware Supplement

DTIC Science & Technology

2010-01-01

December 2008]. • Coating or Printing - coating is the application of a uniform layer of material across the entire width of a web . Printing is...excess solvent by spinning, and drying by tumbling in any air stream. The facility includes, but is not limited to, any washer, dryer , or filter...mergency f ire , r escue o r co mmunications cal ls a nd operated either by the Delaware Emergency Management Agency or by any public agency or

Light effects in the atomic-motion-induced Ramsey narrowing of dark resonances in wall-coated cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Breschi, E.; Schori, C.; Di Domenico, G.

2010-12-15

We report on light shift and broadening in the atomic-motion-induced Ramsey narrowing of dark resonances prepared in alkali-metal vapors contained in wall-coated cells without buffer gas. The atomic-motion-induced Ramsey narrowing is due to the free motion of the polarized atomic spins in and out of the optical interaction region before spin relaxation. As a consequence of this effect, we observe a narrowing of the dark resonance linewidth as well as a reduction of the ground states' light shift when the volume of the interaction region decreases at constant optical intensity. The results can be intuitively interpreted as a dilution ofmore » the intensity effect similar to a pulsed interrogation due to the atomic motion. Finally the influence of this effect on the performance of compact atomic clocks is discussed.« less

Inorganic photovoltaic devices fabricated using nanocrystal spray deposition.

PubMed

Foos, Edward E; Yoon, Woojun; Lumb, Matthew P; Tischler, Joseph G; Townsend, Troy K

2013-09-25

Soluble inorganic nanocrystals offer a potential route to the fabrication of all-inorganic devices using solution deposition techniques. Spray processing offers several advantages over the more common spin- and dip-coating procedures, including reduced material loss during fabrication, higher sample throughput, and deposition over a larger area. The primary difference observed, however, is an overall increase in the film roughness. In an attempt to quantify the impact of this morphology change on the devices, we compare the overall performance of spray-deposited versus spin-coated CdTe-based Schottky junction solar cells and model their dark current-voltage characteristics. Spray deposition of the active layer results in a power conversion efficiency of 2.3 ± 0.3% with a fill factor of 45.7 ± 3.4%, Voc of 0.39 ± 0.06 V, and Jsc of 13.3 ± 3.0 mA/cm(2) under one sun illumination.

FAST TRACK COMMUNICATION High mobility and low operating voltage ZnGaO and ZnGaLiO transistors with spin-coated Al2O3 as gate dielectric

NASA Astrophysics Data System (ADS)

Xia, D. X.; Xu, J. B.

2010-11-01

Spin-coated alumina serving as a gate dielectric in thin film transistors shows interesting dielectric properties for low-voltage applications, despite a moderate capacitance. With Ga singly doped and Ga, Li co-doped ZnO as the active channel layers, typical mobilities of 4.7 cm2 V-1 s-1 and 2.1 cm2 V-1 s-1 are achieved, respectively. At a given gate bias, the operation current is much smaller than the previously reported values in low-voltage thin film transistors, primarily relying on the giant-capacitive dielectric. The reported devices combine advantages of high mobility, low power consumption, low cost and ease of fabrication. In addition to the transparent nature of both the dielectric and semiconducting active channels, the superior electrical properties of the devices may provide a new avenue for future transparent electronics.

High-sensitivity green resist material with organic solvent-free spin-coating and tetramethylammonium hydroxide-free water-developable processes for EB and EUV lithography

NASA Astrophysics Data System (ADS)

Takei, Satoshi; Hanabata, Makoto; Oshima, Akihiro; Kashiwakura, Miki; Kozawa, Takahiro; Tagawa, Seiichi

2015-03-01

We investigated the eco-friendly electron beam (EB) and extreme-ultraviolet (EUV) lithography using a high-sensitive negative type of green resist material derived from biomass to take advantage of organic solvent-free water spin-coating and tetramethylammonium hydroxide(TMAH)-free water-developable techniques. A water developable, non-chemically amplified, high sensitive, and negative tone resist material in EB lithography was developed for environmental affair, safety, easiness of handling, and health of the working people, instead of the common developable process of TMAH. The material design concept to use the water-soluble resist material with acceptable properties such as pillar patterns with less than 100 nm in high EB sensitivity of 10 μC/cm2 and etch selectivity with a silicon-based middle layer in CF4 plasma treatment was demonstrated for EB and EUV lithography.

X-ray photoelectron spectroscopy study of para-substituted benzoic acids chemisorbed to aluminum oxide thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kreil, Justin; Ellingsworth, Edward; Szulczewski, Greg

A series of para-substituted, halogenated (F, Cl, Br, and I) benzoic acid monolayers were prepared on the native oxide of aluminum surfaces by solution self-assembly and spin-coating techniques. The monolayers were characterized by x-ray photoelectron spectroscopy (XPS) and water contact angles. Several general trends are apparent. First, the polarity of the solvent is critical to monolayer formation. Protic polar solvents produced low coverage monolayers; in contrast, nonpolar solvents produced higher coverage monolayers. Second, solution deposition yields a higher surface coverage than spin coating. Third, the thickness of the monolayers determined from XPS suggests the plane of the aromatic ring ismore » perpendicular to the surface with the carboxylate functional group most likely binding in a bidentate chelating geometry. Fourth, the saturation coverage (∼2.7 × 10{sup 14} molecules cm{sup −2}) is independent of the para-substituent.« less

Directionally Aligned Amorphous Polymer Chains via Electrohydrodynamic-Jet Printing: Analysis of Morphology and Polymer Field-Effect Transistor Characteristics.

PubMed

Kim, Yebyeol; Bae, Jaehyun; Song, Hyun Woo; An, Tae Kyu; Kim, Se Hyun; Kim, Yun-Hi; Park, Chan Eon

2017-11-15

Electrohydrodynamic-jet (EHD-jet) printing provides an opportunity to directly assembled amorphous polymer chains in the printed pattern. Herein, an EHD-jet printed amorphous polymer was employed as the active layer for fabrication of organic field-effect transistors (OFETs). Under optimized conditions, the field-effect mobility (μ FET ) of the EHD-jet printed OFETs was 5 times higher than the highest μ FET observed in the spin-coated OFETs, and this improvement was achieved without the use of complex surface templating or additional pre- or post-deposition processing. As the chain alignment can be affected by the surface energy of the dielectric layer in EHD-jet printed OFETs, dielectric layers with varying wettability were examined. Near-edge X-ray absorption fine structure measurements were performed to compare the amorphous chain alignment in OFET active layers prepared by EHD-jet printing and spin coating.

Synthesis of ZnO thin film by sol-gel spin coating technique for H2S gas sensing application

NASA Astrophysics Data System (ADS)

Nimbalkar, Amol R.; Patil, Maruti G.

2017-12-01

In this present work, zinc oxide (ZnO) thin film synthesized by a simple sol-gel spin coating technique. The structural, morphology, compositional, microstructural, optical, electrical and gas sensing properties of the film were studied by using XRD, FESEM, EDS, XPS, HRTEM, Raman, FTIR and UV-vis techniques. The ZnO thin film shows hexagonal wurtzite structure with a porous structured morphology. Gas sensing performance of synthesized ZnO thin film was tested initially for H2S gas at different operating temperatures as well as concentrations. The maximum gas response is achieved towards H2S gas at 300 °C operating temperature, at 100 ppm gas concentration as compared to other gases like CH3OH, Cl2, NH3, LPG, CH3COCH3, and C2H5OH with a good stability.

Vorinostat-eluting poly(DL-lactide-co-glycolide) nanofiber-coated stent for inhibition of cholangiocarcinoma cells

PubMed Central

Song, Yeon Hui; Kim, Chan; Kim, Jungsoo; Seo, Sol-Ji; Jeong, Young-Il; Kang, Dae Hwan

2017-01-01

Purpose The aim of this study was to fabricate a vorinostat (Zolinza™)-eluting nanofiber membrane-coated gastrointestinal (GI) stent and to study its antitumor activity against cholangiocarcinoma (CCA) cells in vitro and in vivo. Methods Vorinostat and poly(DL-lactide-co-glycolide) dissolved in an organic solvent was sprayed onto a GI stent to make a nanofiber-coated stent using an electro-spinning machine. Intact vorinostat and vorinostat released from nanofibers was used to assess anticancer activity in vitro against various CCA cells. The antitumor activity of the vorinostat-eluting nanofiber membrane-coated stent was evaluated using HuCC-T1 bearing mice. Results A vorinostat-incorporated polymer nanofiber membrane was formed on the surface of the GI stent. Vorinostat was continuously released from the nanofiber membrane over 10 days, and its release rate was higher in cell culture media than in phosphate-buffered saline. Released vorinostat showed similar anticancer activity against various CCA cells in vitro compared to that of vorinostat. Like vorinostat, vorinostat released from nanofibers induced acetylation of histone H4 and inhibited histone deacetylases 1⋅3⋅4/5/7 expression in vitro and in vivo. Furthermore, vorinostat nanofibers showed a higher tumor growth inhibition rate in HuCC-T1 bearing mice than vorinostat injections. Conclusion Vorinostat-eluting nanofiber membranes showed significant antitumor activity against CCA cells in vitro and in vivo. We suggest the vorinostat nanofiber-coated stent may be a promising candidate for CCA treatment. PMID:29089762

Cicada-Wing-Inspired Self-Cleaning Antireflection Coatings on Polymer Substrates.

PubMed

Chen, Ying-Chu; Huang, Zhe-Sheng; Yang, Hongta

2015-11-18

The cicada has transparent wings with remarkable self-cleaning properties and high transmittance over the whole visible spectral range, which is derived from periodic conical structures covering the wing surface. Here we report a scalable self-assembly technique for fabricating multifunctional optical coatings that mimic cicada-wing structures. Spin-coated two-dimensional non-close-packed colloidal crystals are utilized as etching masks to pattern subwavelength-structured cone arrays directly on polymer substrates. The resulting gratings exhibit broadband antireflection performance and superhydrophobic properties after surface modification. The dependence of the cone shape and size on the antireflective and self-cleaning properties has also been investigated in this study.

The sol-gel route: A versatile process for up-scaling the fabrication of gas-tight thin electrolyte layers

NASA Astrophysics Data System (ADS)

Viazzi, Céline; Rouessac, Vincent; Lenormand, Pascal; Julbe, Anne; Ansart, Florence; Guizard, Christian

2011-03-01

Sol-gel routes are often investigated and adapted to prepare, by suitable chemical modifications, submicronic powders and derived materials with controlled morphology, which cannot be obtained by conventional solid state chemistry paths. Wet chemistry methods provide attractive alternative routes because mixing of species occurs at the atomic scale. In this paper, ultrafine powders were prepared by a novel synthesis method based on the sol-gel process and were dispersed into suspensions before processing. This paper presents new developments for the preparation of functional materials like yttria-stabilized-zirconia (YSZ, 8% Y2O3) used as electrolyte for solid oxide fuel cells. YSZ thick films were coated onto porous Ni-YSZ substrates using a suspension with an optimized formulation deposited by either a dip-coating or a spin-coating process. The suspension composition is based on YSZ particles encapsulated by a zirconium alkoxide which was added with an alkoxide derived colloidal sol. The in situ growth of these colloids increases significantly the layer density after an appropriated heat treatment. The derived films were continuous, homogeneous and around 20 μm thick. The possible up-scaling of this process has been also considered and the suitable processing parameters were defined in order to obtain, at an industrial scale, homogeneous, crack-free, thick and adherent films after heat treatment at 1400 °C.

Tuning domain size and crystallinity in isoindigo/PCBM organic solar cells via solution shearing

DOE PAGES

Gu, Kevin L.; Zhou, Yan; Gu, Xiaodan; ...

2016-11-01

Despite having achieved the long sought-after performance of 10% power conversion efficiency, high performance organic photovoltaics (OPVs) are still mostly constrained to lab scale devices fabricated by spin coating. Efforts to produce printed OPVs lag considerably behind, and the sensitivity to different fabrication methods highlights the need to develop a comprehensive understanding of the processing-morphology relationship in printing methods. Here we present a systematic experimental investigation of a model low bandgap polymer/fullerene system, poly-isoindigo thienothiophene/PC 61BM, using a lab-scale analogue to roll-to-roll coating as the fabrication tool in order to understand the impact of processing parameters on morphological evolution. Wemore » report that domain size and polymer crystallinity can be tuned by a factor of two by controlling the temperature and coating speed. Lower fabrication temperature simultaneously decreased the phase separation domain size and increased the relative degree of crystallinity in those domains, leading to improved photocurrent. We conclude that domain size in isoindigo/PCBM is dictated by spontaneous phase separation rather than crystal nucleation and growth. Moreover we present a model to describe the temperature dependence of domain size formation in our system, which demonstrates that morphology is not necessarily strictly dependent on the evaporation rate, but rather on the interplay between evaporation and diffusion during the printing process.« less

Lowering of the firing voltage and reducing of the discharge delay time in alternating current plasma display panels by a discontinuous spin-coated LaB{sub 6} film on the MgO protective layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, Jiang, E-mail: dj78291@163.com; Zeng, Baoqing; Zhongshan Institute, University of Electronic Science and Technology of China, 528402 zhongshan

2014-03-15

A spin coated LaB{sub 6} discontinuous film is covered on MgO protective layer to improve the discharge performance of alternating current plasma display panels. Under the premise of high transmittance of more than 90%, a very small amount of polycrystal LaB{sub 6} powders added in an organic solvent are chosen as the coating solution. The discharge characteristics results show that with 250 torr 5% Xe-Ne pressure, the firing voltage and discharge delay time of the test panel with LaB{sub 6}/MgO double protective layer are decreased by 13.4% and 36.5%, respectively, compared with that of conventional MgO protective layer, likely owingmore » to the low work function of LaB{sub 6.} Furthermore, the aging time of the proposed structure is comparable to that of pure MgO protective layer. Therefore, it will not increase the production costs and is highly suitable to be applied for alternating current plasma display panels with low electrical power consumption.« less

Surface modification of polyimide gate insulators for solution-processed 2,7-didecyl[1]benzothieno[3,2-b][1]benzothiophene (C10-BTBT) thin-film transistors.

PubMed

Jang, Kwang-Suk; Kim, Won Soo; Won, Jong-Myung; Kim, Yun-Ho; Myung, Sung; Ka, Jae-Won; Kim, Jinsoo; Ahn, Taek; Yi, Mi Hye

2013-01-21

The surface property of a polyimide gate insulator was successfully modified with an n-octadecyl side-chain. Alkyl chain-grafted poly(amic acid), the polyimide precursor, was synthesized using the diamine comonomer with an alkyl side-chain. By adding a base catalyst to the poly(amic acid) coating solution, the imidization temperature of the spin-coated film could be reduced to 200 °C. The 350 nm-thick polyimide film had a dielectric constant of 3.3 at 10 kHz and a leakage current density of less than 8.7 × 10(-10) A cm(-2), while biased from 0 to 100 V. To investigate the potential of the alkyl chain-grafted polyimide film as a gate insulator for solution-processed organic thin-film transistors (TFTs), we fabricated C(10)-BTBT TFTs. C(10)-BTBT was deposited on the alkyl chain-grafted polyimide gate insulator by spin-coating, forming a well-ordered crystal structure. The field-effect mobility and the on/off current ratio of the TFT device were measured to be 0.20-0.56 cm(2) V(-1) s(-1) and >10(5), respectively.

Sol-Gel Deposited Double Layer TiO₂ and Al₂O₃ Anti-Reflection Coating for Silicon Solar Cell.

PubMed

Jung, Jinsu; Jannat, Azmira; Akhtar, M Shaheer; Yang, O-Bong

2018-02-01

In this work, the deposition of double layer ARC on p-type Si solar cells was carried out by simple spin coating using sol-gel derived Al2O3 and TiO2 precursors for the fabrication of crystalline Si solar cells. The first ARC layer was created by freshly prepared sol-gel derived Al2O3 precursor using spin coating technique and then second ARC layer of TiO2 was deposited with sol-gel derived TiO2 precursor, which was finally annealed at 400 °C. The double layer Al2O3/TiO2 ARC on Si wafer exhibited the low average reflectance of 4.74% in the wavelength range of 400 and 1000 nm. The fabricated solar cells based on double TiO2/Al2O3 ARC attained the conversion efficiency of ~13.95% with short circuit current (JSC) of 35.27 mA/cm2, open circuit voltage (VOC) of 593.35 mV and fill factor (FF) of 66.67%. Moreover, the fabricated solar cells presented relatively low series resistance (Rs) as compared to single layer ARCs, resulting in the high VOC and FF.

A controlled wet-spinning and dip-coating process for preparation of high-permeable TiO2 hollow fiber membranes.

PubMed

Zhang, Qi; Wang, Hua; Fan, Xinfei; Chen, Shuo; Yu, Hongtao; Quan, Xie

2016-01-01

In order to improve the permeate flux of photocatalytic membranes, we present an approach for coupling TiO2 with ceramic hollow fiber membranes. The ceramic hollow fiber membranes with high permeate flux were fabricated by a controlled wet-spinning process using polyethersulfone (PESf) and ceramic powder as precursors and 1-methyl-2-pyrrolidinone as solvent, and the subsequent TiO2 coating was performed by a dip-coating process using tetra-n-butyl titanate as precursor. It has been found that the PESf/ceramic powder ratio could influence the structure of the membranes. Here the as-prepared TiO2 hollow fiber membranes had a pure water flux of 4,450 L/(m(2)·h). The performance of the TiO2 hollow fiber membrane was evaluated using humic acid (HA) as a test substance. The results demonstrated that this membrane exhibited a higher permeate flux under UV irradiation than in the dark and the HA removal efficiency was enhanced. The approach described here provides an operable route to the development of high-permeable photocatalytic membranes for water treatment.

Sensitivity differences between microporous NaY and hierarchical ZSM-5 modified electrodes as ammonia gas sensor

NASA Astrophysics Data System (ADS)

Lisnawati, E.; Agustin, I.; Krisnandi, Y. K.; Triyono, D.

2017-07-01

The hierarchical ZSM-5 had been successfully synthesized with double template using a hydrotermal method and microporous NaY zeolite had been successfully synthesized using a sol-gel method. XRD pattern confirmed hat the as-synthesized materials were ZSM-5 and NaY zeolites. SEM images of ZSM-5 showed that it has a hexagonal shape, which can be called coffin type,and rough surface. The EDS elemental analysis gives Si/Al molar ratio of 24.2. On the other hand, NaY crystals were intergrown in cuboid shapes with Si/Al molar ratio of 2. ZSM-5 and NaY were coated onto the surface of Interdigitated Capacitor (IDC) pattern made of gold/silver/quartz through spin coating method. IDC, ZSM-5/IDC and NaY/IDC were tested using Electrochemical Impedance Spectroscopy (EIS) method. The composite has different sensitivity in range concentration of ammonia 20-300 ppm. IDC has no significant effect of the presence of various concentrations, NaY/IDC and ZSM-5/IDC composite have frequency 100 Hz with R2 = 0.8312 and R2 = 0.8037. The NaY/IDC has higher sensitivity compared toZSM-5/IDC, this could be caused by the higher polarity of NaY compared to ZSM-5 to attract ammonia.

High-throughput preparation of complex multi-scale patterns from block copolymer/homopolymer blend films.

PubMed

Park, Hyungmin; Kim, Jae-Up; Park, Soojin

2012-02-21

A simple, straightforward process for fabricating multi-scale micro- and nanostructured patterns from polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP)/poly(methyl methacrylate) (PMMA) homopolymer in a preferential solvent for PS and PMMA is demonstrated. When the PS-b-P2VP/PMMA blend films were spin-coated onto a silicon wafer, PS-b-P2VP micellar arrays consisting of a PS corona and a P2VP core were formed, while the PMMA macrodomains were isolated, due to the macrophase separation caused by the incompatibility between block copolymer micelles and PMMA homopolymer during the spin-coating process. With an increase of PMMA composition, the size of PMMA macrodomains increased. Moreover, the P2VP blocks have a strong interaction with a native oxide of the surface of the silicon wafer, so that the P2VP wetting layer was first formed during spin-coating, and PS nanoclusters were observed on the PMMA macrodomains beneath. Whereas when a silicon surface was modified with a PS brush layer, the PS nanoclusters underlying PMMA domains were not formed. The multi-scale patterns prepared from copolymer micelle/homopolymer blend films are used as templates for the fabrication of gold nanoparticle arrays by incorporating the gold precursor into the P2VP chains. The combination of nanostructures prepared from block copolymer micellar arrays and macrostructures induced by incompatibility between the copolymer and the homopolymer leads to the formation of complex, multi-scale surface patterns by a simple casting process. This journal is © The Royal Society of Chemistry 2012

Well-Defined Nanostructured, Single-Crystalline TiO2 Electron Transport Layer for Efficient Planar Perovskite Solar Cells.

PubMed

Choi, Jongmin; Song, Seulki; Hörantner, Maximilian T; Snaith, Henry J; Park, Taiho

2016-06-28

An electron transporting layer (ETL) plays an important role in extracting electrons from a perovskite layer and blocking recombination between electrons in the fluorine-doped tin oxide (FTO) and holes in the perovskite layers, especially in planar perovskite solar cells. Dense TiO2 ETLs prepared by a solution-processed spin-coating method (S-TiO2) are mainly used in devices due to their ease of fabrication. Herein, we found that fatal morphological defects at the S-TiO2 interface due to a rough FTO surface, including an irregular film thickness, discontinuous areas, and poor physical contact between the S-TiO2 and the FTO layers, were inevitable and lowered the charge transport properties through the planar perovskite solar cells. The effects of the morphological defects were mitigated in this work using a TiO2 ETL produced from sputtering and anodization. This method produced a well-defined nanostructured TiO2 ETL with an excellent transmittance, single-crystalline properties, a uniform film thickness, a large effective area, and defect-free physical contact with a rough substrate that provided outstanding electron extraction and hole blocking in a planar perovskite solar cell. In planar perovskite devices, anodized TiO2 ETL (A-TiO2) increased the power conversion efficiency by 22% (from 12.5 to 15.2%), and the stabilized maximum power output efficiency increased by 44% (from 8.9 to 12.8%) compared with S-TiO2. This work highlights the importance of the ETL geometry for maximizing device performance and provides insights into achieving ideal ETL morphologies that remedy the drawbacks observed in conventional spin-coated ETLs.

Metallic nanoparticle deposition techniques for enhanced organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Cacha, Brian Joseph Gonda

Energy generation via organic photovoltaic (OPV) cells provide many advantages over alternative processes including flexibility and price. However, more efficient OPVs are required in order to be competitive for applications. One way to enhance efficiency is through manipulation of exciton mechanisms within the OPV, for example by inserting a thin film of bathocuproine (BCP) and gold nanoparticles between the C60/Al and ZnPc/ITO interfaces, respectively. We find that BCP increases efficiencies by 330% due to gains of open circuit voltage (Voc) by 160% and short circuit current (Jsc) by 130%. However, these gains are complicated by the anomalous photovoltaic effect and an internal chemical potential. Exploration in the tuning of metallic nanoparticle deposition on ITO was done through four techniques. Drop casting Ag nanoparticle solution showed arduous control on deposited morphology. Spin-coating deposited very low densities of nanoparticles. Drop casting and spin-coating methods showed arduous control on Ag nanoparticle morphology due to clustering and low deposition density, respectively. Sputtered gold on glass was initially created to aid the adherence of Ag nanoparticles but instead showed a quick way to deposit aggregated gold nanoparticles. Electrodeposition of gold nanoparticles (AuNP) proved a quick method to tune nanoparticle morphology on ITO substrates. Control of deposition parameters affected AuNP size and distribution. AFM images of electrodeposited AuNPs showed sizes ranging from 39 to 58 nm. UV-Vis spectroscopy showed the presence of localized plasmon resonance through absorption peaks ranging from 503 to 614 nm. A linear correlation between electrodeposited AuNP size and peak absorbance was seen with a slope of 3.26 wavelength(nm)/diameter(nm).

Nonequilibrium spin crossover in copper phthalocyanine

NASA Astrophysics Data System (ADS)

Siegert, Benjamin; Donarini, Andrea; Grifoni, Milena

2016-03-01

We demonstrate the nonequilibrium tip induced control of the spin state of copper phthalocyanine on an insulator coated substrate. We find that, under the condition of energetic proximity of many-body neutral excited states to the anionic ground state, the system can undergo a population inversion towards these excited states. The resulting state of the system is accompanied by a change in the total spin quantum number. Experimental signatures of the crossover are the appearance of additional nodal planes in the topographical scanning tunneling microscopy images as well as a strong suppression of the current near the center of the molecule. The robustness of the effect against moderate charge conserving relaxation processes has also been tested.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simoes, A.Z., E-mail: alezipo@yahoo.com; Riccardi, C.S.; Dos Santos, M.L.

Bismuth ferrite thin films were deposited on Pt/Ti/SiO{sub 2}/Si substrates by a soft chemical method and spin-coating technique. The effect of annealing atmosphere (air, N{sub 2} and O{sub 2}) on the structure and electrical properties of the films are reported. X-ray diffraction analysis reveals that the film annealed in air atmosphere is a single-phase perovskite structure. The films annealed in air showed better crystallinity and the presence of a single BFO phase leading to lower leakage current density and superior ferroelectric hysteresis loops at room temperature. In this way, we reveal that BFO film crystallized in air atmosphere by themore » soft chemical method can be useful for practical applications, including nonvolatile digital memories, spintronics and data-storage media.« less

Biomimetic novel nanoporous niobium oxide coating for orthopaedic applications

NASA Astrophysics Data System (ADS)

Pauline, S. Anne; Rajendran, N.

2014-01-01

Niobium oxide was synthesized by sol-gel methodology and a crystalline, nanoporous and adherent coating of Nb2O5 was deposited on 316L SS using the spin coating technique and heat treatment. The synthesis conditions were optimized to obtain a nanoporous morphology. The coating was characterized using attenuated total reflectance-Infrared spectroscopy (ATR-IR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM) and transmission electron microscopy (TEM) and the formation of crystalline Nb2O5 coating with nanoporous morphology was confirmed. Mechanical studies confirmed that the coating has excellent adherence to the substrate and the hardness value of the coating was excellent. Contact angle analysis showed increased hydrophilicity for the coated substrate. In vitro bioactivity test confirmed that the Nb2O5 coating with nanoporous morphology facilitated the growth of hydroxyapatite (HAp). This was further confirmed by the solution analysis test where increased uptake of calcium and phosphorous ions from simulated body fluid (SBF) was observed. Electrochemical evaluation of the coating confirmed that the crystalline coating is insulative and protective in nature and offered excellent corrosion protection to 316L SS. Thus, this study confirmed that the nanoporous crystalline Nb2O5 coating conferred bioactivity and enhanced corrosion resistance on 316L SS.

Integrating nanosphere lithography in device fabrication

NASA Astrophysics Data System (ADS)

Laurvick, Tod V.; Coutu, Ronald A.; Lake, Robert A.

2016-03-01

This paper discusses the integration of nanosphere lithography (NSL) with other fabrication techniques, allowing for nano-scaled features to be realized within larger microelectromechanical system (MEMS) based devices. Nanosphere self-patterning methods have been researched for over three decades, but typically not for use as a lithography process. Only recently has progress been made towards integrating many of the best practices from these publications and determining a process that yields large areas of coverage, with repeatability and enabled a process for precise placement of nanospheres relative to other features. Discussed are two of the more common self-patterning methods used in NSL (i.e. spin-coating and dip coating) as well as a more recently conceived variation of dip coating. Recent work has suggested the repeatability of any method depends on a number of variables, so to better understand how these variables affect the process a series of test vessels were developed and fabricated. Commercially available 3-D printing technology was used to incrementally alter the test vessels allowing for each variable to be investigated individually. With these deposition vessels, NSL can now be used in conjunction with other fabrication steps to integrate features otherwise unattainable through current methods, within the overall fabrication process of larger MEMS devices. Patterned regions in 1800 series photoresist with a thickness of ~700nm are used to capture regions of self-assembled nanospheres. These regions are roughly 2-5 microns in width, and are able to control the placement of 500nm polystyrene spheres by controlling where monolayer self-assembly occurs. The resulting combination of photoresist and nanospheres can then be used with traditional deposition or etch methods to utilize these fine scale features in the overall design.

Effects of P3HT concentration on the electrical properties of the Au/PEDOT:PSS/P3HT/n-GaN hybrid junction structure

NASA Astrophysics Data System (ADS)

Noh, Ji-yeon; Lee, Ha Young; Lim, Kyung-won; Ahn, Hyung Soo; Yi, Sam Nyung; Jeon, Hunsoo; Shin, Min Jeong; Yu, Young Moon; Ha, Dong Han

2017-09-01

An inorganic-organic hybrid junction has been fabricated by spin coating the p-type poly(3- hexylthiophene-2,5-diyl)(P3HT) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS) on an n-type GaN layer. The GaN layer was formed on Al2O3 by metal organic chemical vapor deposition(MOCVD) method. To investigate the effects of P3HT concentration on the electrical properties, we changed P3HT solution concentration and speed of spin coater. The currentvoltage (I-V ) characteristic of Au/PEDOT:PSS/P3HT/n-GaN shows rectifying behavior. The I-V characteristic was examined in the frame work of the thermionic emission model. The most proper rectifying behavior was obtained for 0.6 wt% and thickness below 65 nm of P3HT used diode. We expect that such hybrid structures, suitably developed, might be enable the fabrication of highquality electronic and optoelectronic devices.

Large low-field magnetoresistance in Fe3O4/molecule nanoparticles at room temperature

NASA Astrophysics Data System (ADS)

Yue, F. J.; Wang, S.; Lin, L.; Zhang, F. M.; Li, C. H.; Zuo, J. L.; Du, Y. W.; Wu, D.

2011-01-01

Acetic acid molecule-coated Fe3O4 nanoparticles, 450-650 nm in size, have been synthesized using a chemical solvothermal reduction method. Fourier transform infrared spectroscopy measurements confirm one monolayer acetic acid molecules chemically bond to the Fe3O4 nanoparticles. The low-field magnetoresistance (LFMR) of more than -10% at room temperature and -23% at 140 K is achieved with saturation field of less than 2 kOe. In comparison, the resistivity of cold-pressed bare Fe3O4 nanoparticles is six orders of magnitudes smaller than that of Fe3O4/molecule nanoparticles, and the LFMR ratio is one order of magnitude smaller. Our results indicate that the large LFMR in Fe3O4/molecule nanoparticles is associated with spin-polarized electrons tunnelling through molecules instead of direct nanoparticle contacts. These results suggest that magnetic oxide-molecule hybrid materials are an alternative type of materials to develop spin-based devices by a simple low-cost approach.

Seed Coating: Science or Marketing Spin?

PubMed

Pedrini, Simone; Merritt, David J; Stevens, Jason; Dixon, Kingsley

2017-02-01

Seed coating is the practice of covering seeds with external materials to improve handling, protection, and, to a lesser extent, germination enhancement and plant establishment. With an annual value exceeding US$1 billion dollars, this technology is mostly the preserve of the private research sector, with few links to the scientific community. Here, we analyse the science and industry of seed coating and its contribution to seed establishment and plant performance. We posit that a closer collaboration between academia and industry is critical to realising the potential of seed coating both as a tool for enhancing plant establishment in the face of the challenges posed to agricultural systems and to propel the multibillion-dollar global push for ecological restoration of degraded ecosystems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structure and luminescence properties of Tb3+-doped Lu3Al5O12 films prepared by Pechini sol-gel method

NASA Astrophysics Data System (ADS)

Wang, Jian; Shen, Siqing; Xie, Jianjun; Shi, Ying; Ai, Fei

2011-02-01

Tb3+-doped Lu3Al5O12(hereinafter referred to as LuAG:Tb) films were successfully prepared by Pechini sol-gel process and spin-coating technique on carefully cleaned (111) silicon wafer. The microstructure and optical properties of the LuAG:Tb films were studied by X-ray diffraction (XRD), atomic force microscopy(AFM), as well as photoluminescence (PL) spectra. The XRD results showed that the precursor films started to crystallize at about 900°C. All as-calcined LuAG:Tb films showed the Tb3+ characteristic emission bands.

Structure and luminescence properties of Tb3+-doped Lu3Al5O12 films prepared by Pechini sol-gel method

NASA Astrophysics Data System (ADS)

Wang, Jian; Shen, Siqing; Xie, Jianjun; Shi, Ying; Ai, Fei

2010-10-01

Tb3+-doped Lu3Al5O12(hereinafter referred to as LuAG:Tb) films were successfully prepared by Pechini sol-gel process and spin-coating technique on carefully cleaned (111) silicon wafer. The microstructure and optical properties of the LuAG:Tb films were studied by X-ray diffraction (XRD), atomic force microscopy(AFM), as well as photoluminescence (PL) spectra. The XRD results showed that the precursor films started to crystallize at about 900°C. All as-calcined LuAG:Tb films showed the Tb3+ characteristic emission bands.

Fabrication of TiO2/CuO photoelectrode with enhanced solar water splitting activity

NASA Astrophysics Data System (ADS)

Atabaev, Timur Sh.; Lee, Dae Hun; Hong, Nguyen Hoa

A bilayered TiO2/CuO photoelectrode was fabricated on a fluorine-doped tin oxide FTO substrate by spin-coating and pulsed laser deposition methods. The prepared bilayered system was assessed as a photoelectrode for solar water splitting. The fabricated TiO2/CuO photoelectrode exhibited a higher photocurrent density (0.022mA/cm2 at 1.23V vs. RHE) compared to bare TiO2 photoelectrode (0.013mA/cm2 at 1.23V vs. RHE). This photocurrent density enhancement was attributed to the improved charge separation combined with the improved sunlight harvesting efficiency of a bilayered structure.

Structural and magnetic analysis of Cu, Co substituted NiFe2O4 thin films

NASA Astrophysics Data System (ADS)

Sharma, Hakikat; Bala, Kanchan; Negi, N. S.

2016-05-01

In the present work we prepared NiFe2O4, Ni0.95Cu0.05Fe2O4 and Ni0.94Cu0.05Co0.01 Fe2O4 thin films by metallo-organic decomposition method (MOD) using spin coating technique. The thin films were analyzed by X-ray diffractometer (XRD) and Atomic force microscope (AFM) for structural studies. The XRD patterns confirmed the ferrite phase of thin films. From AFM, we analyzed surface morphology, calculated grain size (GS) and root mean square roughness (RMSR). Room temperature magnetic properties were investigated by vibrating sample magnetometer (VSM).

Enhanced Optical and Electrical Properties of Polymer-Assisted All-Inorganic Perovskites for Light-Emitting Diodes.

PubMed

Ling, Yichuan; Tian, Yu; Wang, Xi; Wang, Jamie C; Knox, Javon M; Perez-Orive, Fernando; Du, Yijun; Tan, Lei; Hanson, Kenneth; Ma, Biwu; Gao, Hanwei

2016-10-01

Highly bright light-emitting diodes based on solution-processed all-inorganic perovskite thin film are demonstrated. The cesium lead bromide (CsPbBr 3 ) created using a new poly(ethylene oxide)-additive spin-coating method exhibits photoluminescence quantum yield up to 60% and excellent uniformity of electrical current distribution. Using the smooth CsPbBr 3 films as emitting layers, green perovskite-based light-emitting diodes (PeLEDs) exhibit electroluminescent brightness and efficiency above 53 000 cd m -2 and 4%: a new benchmark of device performance for all-inorganic PeLEDs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

White polymeric light-emitting diodes with high color rendering index

NASA Astrophysics Data System (ADS)

Niu, Xiaodi; Ma, Liang; Yao, Bing; Ding, Junqiao; Tu, Guoli; Xie, Zhiyuan; Wang, Lixiang

2006-11-01

The efficient white polymeric light-emitting diodes based on a white emissive polymer doped with a red phosphorescent dopant were fabricated by spin-coating method. The emission spectrum of the device is broadened to cover the full visible region by doping the red phosphorescent dye and thereby realizes white emission with high color-rendering index (CRI). By controlling the contents of the doped electron-transporting 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole and the red phosphorescent dopant, a luminous efficiency as high as 5.3cd/A and a power efficiency of 3lm/W were obtained with a CRI of 92.

Eddy current imaging with an atomic radio-frequency magnetometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wickenbrock, Arne, E-mail: wickenbr@uni-mainz.de; Leefer, Nathan; Blanchard, John W.

2016-05-02

We use a radio-frequency {sup 85}Rb alkali-vapor cell magnetometer based on a paraffin-coated cell with long spin-coherence time and a small, low-inductance driving coil to create highly resolved conductivity maps of different objects. We resolve sub-mm features in conductive objects, we characterize the frequency response of our technique, and by operating at frequencies up to 250 kHz we are able to discriminate between differently conductive materials based on the induced response. The method is suited to cover a wide range of driving frequencies and can potentially be used for detecting non-metallic objects with low DC conductivity.

Nickel antimony oxide (NiSb2O6): A fascinating nanostructured material for gas sensing application

NASA Astrophysics Data System (ADS)

Singh, Archana; Singh, Ajendra; Singh, Satyendra; Tandon, Poonam

2016-02-01

Fabrication of nanocrystalline NiSb2O6 thin films via sol-gel spin coating method towards the development of liquefied petroleum gas (LPG) sensor operable at room temperature (25 °C) is being reported. Nanostructural, surface morphological and optical properties of trirutile-type NiSb2O6 have been investigated in order to explore the parameters of interest. The crystallite size has been found to be 19 nm. A detailed sensing performance (sensitivity, sensor response, response and recovery times, reproducibility and long term stability) of NiSb2O6 nanostructures grown on alumina substrate has been investigated.

Fortifying the Bone-Implant Interface Part 1: An In Vitro Evaluation of 3D-Printed and TPS Porous Surfaces.

PubMed

MacBarb, Regina F; Lindsey, Derek P; Bahney, Chelsea S; Woods, Shane A; Wolfe, Mark L; Yerby, Scott A

2017-01-01

An aging society and concomitant rise in the incidence of impaired bone health have led to the need for advanced osteoconductive spinal implant surfaces that promote greater biological fixation ( e.g. for interbody fusion cages, sacroiliac joint fusion implants, and artificial disc replacements). Additive manufacturing, i.e. 3D-printing, may improve bone integration by generating biomimetic spinal implant surfaces that mimic bone morphology. Such surfaces may foster an enhanced cellular response compared to traditional implant surfacing processes. This study investigated the response of human osteoblasts to additive manufactured (AM) trabecular-like titanium implant surfaces compared to traditionally machined base material with titanium plasma spray (TPS) coated surfaces, with and without a nanocrystalline hydroxyapatite (HA) coating. For TPS-coated discs, wrought Ti6Al4V ELI was machined and TPS-coating was applied. For AM discs, Ti6Al4V ELI powder was 3D-printed to form a solid base and trabecular-like porous surface. The HA-coating was applied via a precipitation dip-spin method. Surface porosity, pore size, thickness, and hydrophilicity were characterized. Initial cell attachment, proliferation, alkaline phosphatase (ALP) activity, and calcium production of hFOB cells ( n =5 per group) were measured. Cells on AM discs exhibited expedited proliferative activity. While there were no differences in mean ALP expression and calcium production between TPS and AM discs, calcium production on the AM discs trended 48% higher than on TPS discs ( p =0.07). Overall, HA-coating did not further enhance results compared to uncoated TPS and AM discs. Results demonstrate that additive manufacturing allows for controlled trabecular-like surfaces that promote earlier cell proliferation and trends toward higher calcium production than TPS coating. Results further showed that nanocrystalline HA may not provide an advantage on porous titanium surfaces. Additive manufactured porous titanium surfaces may induce a more osteogenic environment compared to traditional TPS, and thus present as an attractive alternative to TPS-coating for orthopedic spinal implants.

Spectroscopic, and thermal studies of some new binuclear transition metal(II) complexes with hydrazone ligands containing acetoacetanilide and isoxazole.

PubMed

Chen, Zhimin; Wu, Yiqun; Gu, Donghong; Gan, Fuxi

2007-11-01

A new chelating ligand, 2-(2-(5-tert-butylisoxazol-3-yl)hydrazono)-N-(2,4-dimethylphenyl)-3-oxobutanamide (HL), and its four binuclear transition metal complexes, M(2)(L)(2) (micro-OCH(3))(2) [M=Ni(II), Co(II), Cu(II), Zn(II)], were synthesized using the procedure of diazotization, coupling and metallization. Their structures were postulated based on elemental analysis, (1)H NMR, MALDI-MS, FT-IR spectra and UV-vis electronic absorption spectra. Smooth films of these complexes on K9 glass substrates were prepared using the spin-coating method and their absorption properties were evaluated. The thermal properties of the metal(II) complexes were investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). Different thermodynamic and kinetic parameters namely activation energy (E*), enthalpy of activation (DeltaH*), entropy of activation (DeltaS*) and free energy change of activation (DeltaG*) are calculated using Coats-Redfern (CR) equation.

Electrochemical Properties of RuO2 Electrodes as a Function of Thin Film Thickness

NASA Astrophysics Data System (ADS)

Li, Xiang; Xiong, Jian; Luo, Yuan; Luo, Yongmei

2018-01-01

A thin film RuO2 electrode was prepared by spin coating thermal decomposition methods. Precursor containing RuCl3·nH2O and isopropyl alcohol was coated on tantalum substrate and annealed at 250-260°C for 3 h to form a thin film RuO2 electrode of about 2.5 μm, 5.6 μm, 11.4 μm, and 14.5 μm in thickness. X-ray diffraction revealed that peak intensities of those electrodes were similar and close to each other. Scanning electron microscopy showed that thin film of 5.6 μm in thickness was dense and free of cracks. Electrochemical performances of electrodes were examined by cyclic voltammetry, galvanostatic charge/discharge as well as equivalent series resistance. The highest specific capacitance value of 725 F g-1 was registered for the electrode of 5.6 μm in thickness with good constant current charge/discharge and equivalent series resistance of 0.36 Ω as well as cyclic stability.

Enhanced optophysical properties of poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3] thiadiazol-4,8-diyl)] via addition of TiO{sub 2} nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fuzi, Siti Aishah Ahmad, E-mail: aishah-fuzi@yahoo.com; Jumali, Mohammad Hafizuddin Hj, E-mail: hafizhj@ukm.edu.my; Al-Asbahi, Bandar Ali Abdulqader, E-mail: alasbahibandar@gmail.com

2015-09-25

This work investigated the effect on 5 wt% addition of TiO{sub 2} nanoparticles (NPs) on the optical absorption characteristics of Poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3] thiadiazol-4,8-diyl)] (F8BT). Both materials were mixed using solution blending method and then spin coated onto ITO-coated glass substrate at 1000 rpm for 30s. The optical properties of the nanocomposite were determined using UV-Vis spectroscopy. Compares to pristine film, the absorption peak of the nanocomposite film improved and shifted to longer wavelength indicating reduction in the direct and indirect band gaps. Better optophysical properties of F8BT/TiO{sub 2} nanocomposites is believed due to compatible band structures and efficient charge trapping effect displayedmore » by the NPs.« less

Spin-on metal oxide materials with high etch selectivity and wet strippability

NASA Astrophysics Data System (ADS)

Yao, Huirong; Mullen, Salem; Wolfer, Elizabeth; McKenzie, Douglas; Rahman, Dalil; Cho, JoonYeon; Padmanaban, Munirathna; Petermann, Claire; Hong, SungEun; Her, YoungJun

2016-03-01

Metal oxide or metal nitride films are used as hard mask materials in semiconductor industry for patterning purposes due to their excellent etch resistances against the plasma etches. Chemical vapor deposition (CVD) or atomic layer deposition (ALD) techniques are usually used to deposit the metal containing materials on substrates or underlying films, which uses specialized equipment and can lead to high cost-of-ownership and low throughput. We have reported novel spin-on coatings that provide simple and cost effective method to generate metal oxide films possessing good etch selectivity and can be removed by chemical agents. In this paper, new spin-on Al oxide and Zr oxide hard mask formulations are reported. The new metal oxide formulations provide higher metal content compared to previously reported material of specific metal oxides under similar processing conditions. These metal oxide films demonstrate ultra-high etch selectivity and good pattern transfer capability. The cured films can be removed by various chemical agents such as developer, solvents or wet etchants/strippers commonly used in the fab environment. With high metal MHM material as an underlayer, the pattern transfer process is simplified by reducing the number of layers in the stack and the size of the nano structure is minimized by replacement of a thicker film ACL. Therefore, these novel AZ® spinon metal oxide hard mask materials can potentially be used to replace any CVD or ALD metal, metal oxide, metal nitride or spin-on silicon-containing hard mask films in 193 nm or EUV process.

Interactions of chlorine plasmas with silicon chloride-coated reactor walls during and after silicon etching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khare, Rohit; Srivastava, Ashutosh; Donnelly, Vincent M.

2012-09-15

The interplay between chlorine inductively coupled plasmas (ICP) and reactor walls coated with silicon etching products has been studied in situ by Auger electron spectroscopy and line-of-sight mass spectrometry using the spinning wall method. A bare silicon wafer mounted on a radio frequency powered electrode (-108 V dc self-bias) was etched in a 13.56 MHz, 400 W ICP. Etching products, along with some oxygen due to erosion of the discharge tube, deposit a Si-oxychloride layer on the plasma reactor walls, including the rotating substrate surface. Without Si-substrate bias, the layer that was previously deposited on the walls with Si-substrate biasmore » reacts with Cl-atoms in the chlorine plasma, forming products that desorb, fragment in the plasma, stick on the spinning wall and sometimes react, and then desorb and are detected by the mass spectrometer. In addition to mass-to-charge (m/e) signals at 63, 98, 133, and 168, corresponding to SiCl{sub x} (x = 1 - 4), many Si-oxychloride fragments with m/e = 107, 177, 196, 212, 231, 247, 275, 291, 294, 307, 329, 345, 361, and 392 were also observed from what appear to be major products desorbing from the spinning wall. It is shown that the evolution of etching products is a complex 'recycling' process in which these species deposit and desorb from the walls many times, and repeatedly fragment in the plasma before being detected by the mass spectrometer. SiCl{sub 3} sticks on the walls and appears to desorb for at least milliseconds after exposure to the chlorine plasma. Notably absent are signals at m/e = 70 and 72, indicating little or no Langmuir-Hinshelwood recombination of Cl on this surface, in contrast to previous studies done in the absence of Si etching.« less

A 3He-129Xe co-magnetometer probed by a Rb magnetometer with Ramsey-pulse technique

NASA Astrophysics Data System (ADS)

Sheng, Dong; Kabcenell, Aaron; Romalis, Michael

2013-05-01

We report the recent progress in development of a new kind of co-magnetometer, benifiting from both the long spin coherence time of a noble gas and a highly sensitive alkali metal magnetometer. Due to the Fermi-contact interaction between alkali metal electron spin and noble gas nuclear spin the effective magnetization of the noble gas is enhanced by a factor of 6 to 600, allowing near quantum-limited detection of nuclear spins. Collisions between polarized alkali atoms and noble gas also introduce a large shift to the nuclear spin precession frequency. We reduce this effect by using Ramsey pulse techniques to measure the noble gas spin precession frequency ``in the dark'' by turning off the pumping laser between Ramsey pulses. A furthur reduction of the back-hyperpolarization from the noble gas can be achieved by controlling the cell temperature on short time scale. We showed that a 3He-129Xe Ramsey co-magnetometer is effective in cancelling fluctuations of external magnetic fields and gradients and developed cells with sufficient 129Xe T2 time without surface coatings. The new co-magnetometer has potential applications for many precision measurements, such as searches for spin-gravity couplings, electric dipole moments, and nuclear spin gyroscopes. Supported by DARPA.

Controlled drug delivery from composites of nanostructured porous silicon and poly(L-lactide).

PubMed

McInnes, Steven J P; Irani, Yazad; Williams, Keryn A; Voelcker, Nicolas H

2012-07-01

Porous silicon (pSi) and poly(L-lactide) (PLLA) both display good biocompatibility and tunable degradation behavior, suggesting that composites of both materials are suitable candidates as biomaterials for localized drug delivery into the human body. The combination of a pliable and soft polymeric material with a hard inorganic porous material of high drug loading capacity may engender improved control over degradation and drug release profiles and be beneficial for the preparation of advanced drug delivery devices and biodegradable implants or scaffolds. In this work, three different pSi and PLLA composite formats were prepared. The first format involved grafting PLLA from pSi films via surface-initiated ring-opening polymerization (pSi-PLLA [grafted]). The second format involved spin coating a PLLA solution onto oxidized pSi films (pSi-PLLA [spin-coated]) and the third format consisted of a melt-cast PLLA monolith containing dispersed pSi microparticles (pSi-PLLA [monoliths]). The surface characterization of these composites was performed via infrared spectroscopy, scanning electron microscopy, atomic force microscopy and water contact angle measurements. The composite materials were loaded with a model cytotoxic drug, camptothecin (CPT). Drug release from the composites was monitored via fluorimetry and the release profiles of CPT showed distinct characteristics for each of the composites studied. In some cases, controlled CPT release was observed for more than 5 days. The PLLA spin coat on pSi and the PLLA monolith containing pSi microparticles both released a CPT payload in accordance with the Higuchi and Ritger-Peppas release models. Composite materials were also brought into contact with human lens epithelial cells to determine the extent of cytotoxicity. We observed that all the CPT containing materials were highly efficient at releasing bioactive CPT, based on the cytotoxicity data.

Fabrication and characterization of highly transparent and conductive indium tin oxide films made with different solution-based methods

NASA Astrophysics Data System (ADS)

Xia, N.; Gerhardt, R. A.

2016-11-01

Solution-based fabrication methods can greatly reduce the cost and broaden the applications of transparent conducting oxides films, such as indium tin oxide (ITO) films. In this paper, we report on ITO films fabricated by spin coating methods on glass substrates with two different ITO sources: (1) a commercial ITO nanopowder water dispersion and (2) a sol-gel ITO solution. A simple and fast air annealing process was used to treat as-coated ITO films on a controlled temperature hot plate. Thermogravimetric analysis and x-ray diffraction showed that highly crystalline ITO films were formed after the annealing steps. The final ITO films had a good combination of optical properties and electrical properties, especially for films made from five layers of sol-gel ITO (92.66% transmittance and 8.7 × 10-3 Ω cm resistivity). The surface morphology and conducting network on the ITO films were characterized by non-contact and current atomic force microscopy. It was found that conducting paths were only partially connected for the nanoparticle ITO dispersion films, whereas the sol-gel ITO films had a more uniformly distributed conducting network on the surface. We also used the sol-gel ITO films to fabricate a simple liquid crystal display (LCD) device to demonstrate the excellent properties of our films.

Electro-Caloric Properties of BT/PZT Multilayer Thin Films Prepared by Sol-Gel Method.

PubMed

Kwon, Min-Su; Lee, Sung-Gap; Kim, Kyeong-Min

2018-09-01

In this study, Barium Titanate (BT)/Lead Zirconate Titanate (PZT) multilayer thin films were fabricated by the spin-coating method on Pt (200 nm)/Ti (10 nm) SiO2 (100 nm)/P-Si (100) substrates using BaTiO3 and Pb(Zr0.90Ti0.10)O3 metal alkoxide solutions. The coating and heating procedure was repeated several times to form the multilayer thin films. All of BT/PZT multilayer thin films show X-ray diffraction patterns typical to a polycrystalline perovskite structure and a uniform and void free grain microstructure. The thickness of the BT and PZT film by one-cycle of drying/sintering was approximately 50 nm and all of the films consisted of fine grains with a flat surface morphology. The electrocaloric properties of BT/PZT thin films were investigated by indirect estimation. The results showed that the temperature change ΔT can be calculated as a function of temperature using Maxwell's relation; the temperature change reaches a maximum value of ~1.85 °C at 135 °C under an applied electric field of 260 kV/cm.

Homogeneous PCBM layers fabricated by horizontal-dip coating for efficient bilayer heterojunction organic photovoltaic cells.

PubMed

Huh, Yoon Ho; Bae, In-Gon; Jeon, Hong Goo; Park, Byoungchoo

2016-10-31

We herein report a homogeneous [6,6]-phenyl C₆₁ butyric acid methyl ester (PCBM) layer, produced by a solution process of horizontal-dipping (H-dipping) to improve the photovoltaic (PV) effects of bilayer heterojunction organic photovoltaic cells (OPVs) based on a bi-stacked poly(3-hexylthiophene) (P3HT) electron donor layer and a PCBM electron acceptor layer (P3HT/PCBM). It was shown that a homogeneous and uniform coating of PCBM layers in the P3HT/PCBM bilayer OPVs resulted in reliable and reproducible device performance. We recorded a power conversion efficiency (PCE) of 2.89%, which is higher than that (2.00%) of bilayer OPVs with a spin-coated PCBM layer. Moreover, introducing surfactant additives of poly(oxyethylene tridecyl ether) (PTE) into the homogeneous P3HT/PCBM PV layers resulted in the bilayer OPVs showing a PCE value of 3.95%, which is comparable to those of conventional bulk-heterojunction (BHJ) OPVs (3.57-4.13%) fabricated by conventional spin-coating. This improved device performance may be attributed to the selective collection of charge carriers at the interfaces among the active layers and electrodes due to the PTE additives as well as the homogeneous formation of the functional PCBM layer on the P3HT layer. Furthermore, H-dip-coated PCBM layers were deposited onto aligned P3HT layers by a rubbing technique, and the rubbed bilayer OPV exhibited improved in-plane anisotropic PV effects with PCE anisotropy as high as 1.81, which is also higher than that (1.54) of conventional rubbed BHJ OPVs. Our results suggest that the use of the H-dip-coating process in the fabrication of PCBM layers with the PTE interface-engineering additive could be of considerable interest to those seeking to improve PCBM-based opto-electrical organic thin-film devices.

Effect of the Ti/Si ratio of spin coating solutions on surface passivation of crystalline silicon by TiO x -SiO x composite films

NASA Astrophysics Data System (ADS)

Yoshiba, Shuhei; Tanitsu, Katsuya; Suda, Yoshiyuki; Kamisako, Koichi

2017-06-01

Passivation films or antireflection coatings are generally prepared using costly vacuum or high-temperature processes. Thus, we report the preparation of TiO x -SiO x composite films by novel spin coatable solutions for the synthesis of low-cost passivation coating materials. The desired films were formed by varying the mixing ratios of TiO x and SiO x , and the resulting films exhibited excellent surface passivation properties. For the p-type wafer, an optimal effective surface recombination velocity (S eff) of 93 cm/s was achieved at \\text{TiO}x:\\text{SiO}x = 6:4, while a surface recombination current density (J 0s) of 195 fA/cm2 was obtained. In contrast, for the n-type wafer, an S eff of 27 cm/s and a J 0s of 38 fA/cm2 were achieved at \\text{TiO}x:\\text{SiO}x = 8:2. This excellent surface passivation effect could be attributed to the low interface state density and high positive fixed charge density. Furthermore, the thickness of the interfacial SiO x layer was determined to be important for obtaining the desired surface passivation effect.

Electrospinning Robot for Regenerative Coating of Implants

NASA Astrophysics Data System (ADS)

Gerstenhaber, Jonathan A.

Electrospinning of nanofibrous mats and scaffolds enables generation of scaffolding that is not only highly porous, but also has a structure that essentially mimics the natural basement membrane. As a result, the method has proliferated extensively, and is commonly used for diverse applications such as water filtration or tissue engineering, the latter of which may involve the use of natural or synthetic materials. Common laboratory scale electrospinning setups can be built inexpensively with merely a syringe pump, a high voltage supply, and an aluminum foil target. These systems, however, are limited to flat target surface geometries that span several centimeters. While a scaffold can be cut or folded to conform to a bone or other biological surface, spinning directly onto a surface with significant peaks and troughs results in poor fiber uniformity. Furthermore, if an alteration of fiber properties is preferred, the high voltage setup limits user access and customization of parameters during the spinning period. Finally, control of the electric field is compromised by the proximity of grounded electrical components. As its first aim, this project develops a robotic control system to enable custom coatings of arbitrary surfaces. By augmenting the traditional electrospinning system with a three-dimensional robotic control system, electric field focusing fibers, and additional aerodynamic forces terms 'electroblowing', the device can be produced across targets with strong topographic anisotropy. The second aim continues to enhance these attributes with biocompatible soy based scaffolds. Craniofacial implants are often complex in geometry, and conformal bandages are particularly hard to produce in these areas. Soy based scaffolds will be produced for 3D-printed replicas of these situations. Finally, the methods developed across this aim enables the development and use of a handheld electrospinning system that combines a coaxial high velocity air flow with the high voltage spinning element to reduce effects of operator error. The final goal of the thesis is to test whether fiber control successfully reduces effects of fiber anisotropy in vitro and to use the enhanced fiber control mechanisms to produce scaffolds with significant anisotropy, depositing aligned fibers at a target point to eventually enable generation of scaffolds with programmable variable spatial alignment similar to tendon. When completed, the systems described will enable custom production of coatings or scaffolds for functionality as scaffolding on medically relevant surfaces. Specifically, this means first, that scaffolds can be used with confidence to improve fixation even of non-cylindrical implants and enhance local tissue integration, and second, that implants can be customized with areas of 'guidance' fibers or local drug depots to either promote regeneration and population by surrounding tissue or mimic natural anisotropic cues necessary for mechanical or biological functionality.

Synthesis and characterization of polypyrrole and its application for solar cell

NASA Astrophysics Data System (ADS)

Almuntaser, Faisal M. A.; Majumder, Sutripto; Baviskar, Prashant K.; Sali, Jaydeep V.; Sankapal, B. R.

2017-08-01

In this report, the fabrication of a solar cell device with the structures FTO/PPy/PTh/ZnO/Al was performed using wet chemical synthesis methods in open environment. The cost-effective methods like CBD, SILAR, and spin coating have been used for the synthesis. The effect of thickness of PPy active layer on the device performance is investigated. Features such as structural, morphological, and chemical bonding of the layers have been investigated using X-ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy and are discussed herein. Effects of PPy thickness on current-voltage characteristics have been studied under dark and illumination at 1 Sun (100 mW/cm2, AM 1.5 G) condition to study the solar cell performance.

CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Novel Route to Fabrication of Metal-Sandwiched Nanoscale Tapered Structures

NASA Astrophysics Data System (ADS)

Zhang, Yang; Yu, Da-Peng

2009-08-01

Tapered dielectric structures in metal have exhibited extraordinary performance in both surface plasmon polariton (SPP) waveguiding and SPP focusing. This is crucial to plasmonic research and industrial plasmonic device integration. We present a method that facilitates easy fabrication of smooth-surfaced sub-micron tapered structures in large scale simply with electron beam lithography (EBL). When a PMMA layer is spin-coated on previously-EBL-defined PMMA structures, steep edges can be transformed into a declining slope to form tapered PMMA structures, scaled from 10 nm to 1000 nm. Despite the simplicity of our method, patterns with PMMA surface smoothness can be well-positioned and replicated in large numbers, which therefore gives scientists easy access to research on the properties of tapered structures.

Effect of Fe incorporation on the optical behavior of ZnO thin films prepared by sol-gel derived spin coating techniques

NASA Astrophysics Data System (ADS)

Rakkesh, R. Ajay; Malathi, R.; Balakumar, S.

2013-02-01

In this work, Fe doped Zinc Oxide (ZnO) thin films were fabricated on the glass substrate by sol-gel derived spin coating technique. X-ray Diffraction studies revealed that the obtained pure and Fe doped ZnO thin films were in the wurtzite and spinel phase respectively. The three well defined Raman lines at 432, 543 and 1091 cm-1 also confirmed the lattice structure of the ZnO thin film has wurtzite symmetry. While doping Fe atoms in the ZnO, there was a significant change in the phase from wurtzite to spinel structure; owing to Fe (III) ions being incorporated into the lattice through substitution of Zn (II) ions. Room temperature PL spectra showed that the role of defect mediated red emissions at 612 nm was due to radial recombination of a photogenerated hole with an electron that belongs to the Fe atoms, which were discussed in detail.

Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of ultrathin block copolymer films.

PubMed

Huang, Changchun; Wen, Gangyao; Li, Jingdan; Wu, Tao; Wang, Lina; Xue, Feifei; Li, Hongfei; Shi, Tongfei

2016-09-15

Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of spin-coated polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films (<20nm thick) were mainly investigated by atomic force microscopy. Surface chemical analysis of the ultrathin films annealed for different times were performed using X-ray photoelectron spectroscopy and contact angle measurement. With the annealing of acetone vapor, dewetting of the films with different thicknesses occur via the spinodal dewetting and the nucleation and growth mechanisms, respectively. The PS-b-PMMA films rupture into droplets which first coalesce into large ones to reduce the surface free energy. Then the large droplets rupture into small ones to increase the contact area between PMMA blocks and acetone molecules resulting from ultimate migration of PMMA blocks to droplet surface, which is a novel dewetting process observed in spin-coated films for the first time. Copyright © 2016 Elsevier Inc. All rights reserved.

Drying temperature effects on electrical and optical properties of poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) thin film

NASA Astrophysics Data System (ADS)

Azhar, N. E. A.; Affendi, I. H. H.; Shafura, A. K.; Shariffudin, S. S.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2016-07-01

Temperature effects on electrical and optical properties of a representative semiconducting polymer, poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV), has recently attracted much attention. The MEH-PPV thin films were deposited at different drying temperature (anneal temperature) using spin-coating technique. The spin coating technique was used to produce uniform film onto large area. The MEH-PPV was dissolved in toluene solution to exhibits different optical and electrical properties. The absorption coefficient and bandgap was measured using UV-Visible-NIR (UV-VIS-NIR). The bandgap of MEH-PPV was effect by the thickness of thin films. For electrical properties, two-point probe was used to characterize the current-voltage measurement. The current-voltage measurement shows that the MEH-PPV thin films become more conductive at high temperature. This study will provide better performance and suitable for optoelectronic device especially OLEDs applications.

Drying temperature effects on electrical and optical properties of poly[2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azhar, N. E. A., E-mail: najwaezira@yahoo.com; Affendi, I. H. H., E-mail: irmahidayanti.halim@gmail.com; Shafura, A. K., E-mail: shafura@ymail.com

Temperature effects on electrical and optical properties of a representative semiconducting polymer, poly[2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV), has recently attracted much attention. The MEH-PPV thin films were deposited at different drying temperature (anneal temperature) using spin-coating technique. The spin coating technique was used to produce uniform film onto large area. The MEH-PPV was dissolved in toluene solution to exhibits different optical and electrical properties. The absorption coefficient and bandgap was measured using UV-Visible-NIR (UV-VIS-NIR). The bandgap of MEH-PPV was effect by the thickness of thin films. For electrical properties, two-point probe was used to characterize the current-voltage measurement. The current-voltage measurement showsmore » that the MEH-PPV thin films become more conductive at high temperature. This study will provide better performance and suitable for optoelectronic device especially OLEDs applications.« less

Fabrication of ZnO Thin Films by Sol-Gel Spin Coating and Their UV and White-Light Emission Properties

NASA Astrophysics Data System (ADS)

Kumar, Mirgender; Dubey, Sarvesh; Rajendar, Vanga; Park, Si-Hyun

2017-10-01

ZnO thin films have been fabricated by the sol-gel spin-coating technique and annealed under different conditions, and their ultraviolet (UV) and white-light emission properties investigated. Different ambient conditions including oxygen, nitrogen, zinc-rich nitrogen, and vacuum were used to tune the main properties of the ZnO thin films. The resistivity varied from the conductive to semi-insulating regime, and the luminescence emission from fairly intense UV to polychromatic. The emission intensity was also found to be a function of the annealing conditions. Possible routes to compensate the loss of emission characteristics are discussed. X-ray photoelectron spectroscopy (XPS) analysis was carried out to detect the chemical states of the zinc/oxygen species. The changes in the electrical and emission properties are explained based on annihilation/formation of inherent donor/acceptor-type defects. Such ZnO thin films could have potential applications in solid-state lighting.

Vapour-Deposited Cesium Lead Iodide Perovskites: Microsecond Charge Carrier Lifetimes and Enhanced Photovoltaic Performance

PubMed Central

2017-01-01

Metal halide perovskites such as methylammonium lead iodide (MAPbI3) are highly promising materials for photovoltaics. However, the relationship between the organic nature of the cation and the optoelectronic quality remains debated. In this work, we investigate the optoelectronic properties of fully inorganic vapour-deposited and spin-coated black-phase CsPbI3 thin films. Using the time-resolved microwave conductivity technique, we measure charge carrier mobilities up to 25 cm2/(V s) and impressively long charge carrier lifetimes exceeding 10 μs for vapour-deposited CsPbI3, while the carrier lifetime reaches less than 0.2 μs in the spin-coated samples. Finally, we show that these improved lifetimes result in enhanced device performance with power conversion efficiencies close to 9%. Altogether, these results suggest that the charge carrier mobility and recombination lifetime are mainly dictated by the inorganic framework rather than the organic nature of the cation. PMID:28852710

Sol-gel spin coated well adhered MoO3 thin films as an alternative counter electrode for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Mutta, Geeta R.; Popuri, Srinivasa R.; Wilson, John I. B.; Bennett, Nick S.

2016-11-01

In this work, we aim to develop a viable, inexpensive and non-toxic material for counter electrodes in dye sensitized solar cells (DSSCs). We employed an ultra-simple synthesis process to deposit MoO3 thin films at low temperature by sol-gel spin coating technique. These MoO3 films showed good transparency. It is predicted that there will be 150 times reduction of precursors cost by realizing MoO3 thin films as a counter electrode in DSSCs compared to commercial Pt. We achieved a device efficiency of about 20 times higher than that of the previous reported values. In summary we develop a simple low cost preparation of MoO3 films with an easily scaled up process along with good device efficiency. This work encourages the development of novel and relatively new materials and paves the way for massive reduction of industrial costs which is a prime step for commercialization of DSSCs.

Large magnetoresistance in Fe3O4/molecule nanoparticles

NASA Astrophysics Data System (ADS)

Wang, S.; Yue, F. J.; Lin, L.; Shi, Y. J.; Wu, D.

2010-08-01

In this work, we successfully fabricate Fe3O4 nanoparticles self-assembled with molecules to explore a new approach of studying the molecular spintronics. Fourier transform infrared spectroscopy measurements indicate that one monolayer molecules chemically bonds to the Fe3O4 nanoparticles and the physically absorbed molecules do not exist in the samples. The magnetoresistance (MR) of molecule fully coated ~10 nm size nanoparticles is up to 7.3% at room temperature and 17.5% at 115 K under a field of 5.8 kOe. And the MR ratio is more than two times larger than that of pure Fe3O4 nanoparticles. This enhanced MR is likely arising from weak spin scattering while carriers transport through the molecules. Moreover, a very large low field magnetoresistance is also observed with ~500nm ferromagnetic Fe3O4 nanoparticles coated with acetic acid molecules. Those features open a door for the development of future spin-based molecular electronics.

Electrical and optical properties of p-type codoped ZnO thin films prepared by spin coating technique

NASA Astrophysics Data System (ADS)

Pathak, Trilok Kumar; Kumar, Vinod; Swart, H. C.; Purohit, L. P.

2016-03-01

Undoped, doped and codoped ZnO thin films were synthesized on glass substrates using a spin coating technique. Zinc acetate dihydrate, ammonium acetate and aluminum nitrate were used as precursor for zinc, nitrogen and aluminum, respectively. X-ray diffraction shows that the thin films have a hexagonal wurtzite structure for the undoped, doped and co-doped ZnO. The transmittance of the films was above 80% and the band gap of the film varied from 3.20 eV to 3.24 eV for undoped and doped ZnO. An energy band diagram to describe the photoluminescence from the thin films was also constructed. This diagram includes the various defect levels and possible quasi-Fermi levels. A minimum resistivity of 0.0834 Ω-cm was obtained for the N and Al codoped ZnO thin films with p-type carrier conductivity. These ZnO films can be used as a window layer in solar cells and in UV lasers.

Hybrid microfabrication of nanofiber-based sheets and rods for tissue engineering applications.

PubMed

Park, Suk-Hee; Kim, Min Sung; Lee, Dasom; Choi, Yong Whan; Kim, Deok-Ho; Suh, Kahp-Yang

2013-12-01

Electrospun nanofibers have been developed into a variety of forms for tissue engineering scaffolds to regulate the cellular functions guided by nanotopographical cues. Here, we have successfully fabricated nanofiber-based scaffold complexes of rod and sheet type by combining the three microfabrication techniques of electrospinning, spin coating, and polymer melt deposition. It was demonstrated that this hybrid fabrication could produce uniaxially aligned nanofiber scaffolds supported by a thin film, allowing for a mechanically enforced substrate for cell culture as well as facile scaffold manipulation. The results of cell analysis indicated that nanofibers on spin-coated films could provide contact guidance effects on cells and retain them even after manipulation. As an application of the cell-laden nanofiber film, we built a rod-type structure by rolling up the film around a mechanically supporting core microfiber, which was incorporated by polymer melt deposition. A biocompatible and biodegradable polymer, polycaprolactone, was used throughout the processes and thus could be used as a directly implantable substitute in tissue regeneration.

Power and Thermal Technologies for Air and Space - Scientific Research Program. Delivery Order 0020: Advanced Conductors and Thermal Science

DTIC Science & Technology

2014-03-01

4.31. Thermal conductivity of CNT/Carbon foam substrate 4.4.3.3 Post-growth Nickel Coating Plating CNTs/carbon foam samples with nickel provides a...will be necessary to conduct large scale synthesis of textured Ca-Co-O on the amorphous- buffered n-type oxide substrate using sol-gel spin- coating and... Conductors and Thermal Science Evan L. Thomas, Qiuhong N. Zhang, Helen Shen, Serhiy N. Leontsev, John P. Murphy, Jack L. Burke, Lyle Brunke, and

Nanostructured hydroxyapatite/poly(lactic-co-glycolic acid) composite coating for controlling magnesium degradation in simulated body fluid.

PubMed

Johnson, Ian; Akari, Khalid; Liu, Huinan

2013-09-20

Biodegradable magnesium (Mg) and its alloys have many attractive properties (e.g. comparable mechanical properties to cortical bone) for orthopedic implant applications, but they degrade too rapidly in the human body to meet clinical requirements. Nanostructured hydroxyapatite (nHA)/poly(lactic-co-glycolic acid) (PLGA) composite coatings provide synergistic properties for controlling degradation of Mg-based substrates and improving bone-implant integration. In this study, nHA/PLGA composites were spin coated onto Mg-based substrates and the results showed that the nHA/PLGA coatings retained nano-scale features with nHA dispersed in PLGA matrix. In comparison with non-coated Mg, the nHA/PLGA composite coated Mg increased the corrosion potential and decreased the corrosion current in revised simulated body fluid (rSBF). After 24 h of immersion in rSBF, increased calcium phosphate (CaP) deposition and formation of Mg-substituted CaP rosettes were observed on the surface of the nHA/PLGA coated Mg, indicating greater bioactivity. In contrast, no significant CaP was deposited on the PLGA coated Mg. Since both PLGA coating and nHA/PLGA coating showed some degree of delamination from Mg-based substrates during extended immersion in rSBF, the coating processing and properties should be further optimized in order to take full advantage of biodegradable Mg and nHA/PLGA nanocomposites for orthopedic applications.

Nanostructured hydroxyapatite/poly(lactic-co-glycolic acid) composite coating for controlling magnesium degradation in simulated body fluid

NASA Astrophysics Data System (ADS)

Johnson, Ian; Akari, Khalid; Liu, Huinan

2013-09-01

Biodegradable magnesium (Mg) and its alloys have many attractive properties (e.g. comparable mechanical properties to cortical bone) for orthopedic implant applications, but they degrade too rapidly in the human body to meet clinical requirements. Nanostructured hydroxyapatite (nHA)/poly(lactic-co-glycolic acid) (PLGA) composite coatings provide synergistic properties for controlling degradation of Mg-based substrates and improving bone-implant integration. In this study, nHA/PLGA composites were spin coated onto Mg-based substrates and the results showed that the nHA/PLGA coatings retained nano-scale features with nHA dispersed in PLGA matrix. In comparison with non-coated Mg, the nHA/PLGA composite coated Mg increased the corrosion potential and decreased the corrosion current in revised simulated body fluid (rSBF). After 24 h of immersion in rSBF, increased calcium phosphate (CaP) deposition and formation of Mg-substituted CaP rosettes were observed on the surface of the nHA/PLGA coated Mg, indicating greater bioactivity. In contrast, no significant CaP was deposited on the PLGA coated Mg. Since both PLGA coating and nHA/PLGA coating showed some degree of delamination from Mg-based substrates during extended immersion in rSBF, the coating processing and properties should be further optimized in order to take full advantage of biodegradable Mg and nHA/PLGA nanocomposites for orthopedic applications.

Biocorrosion of TiO2 nanoparticle coating of Ti-6Al-4V in DMEM under specific in vitro conditions

NASA Astrophysics Data System (ADS)

Höhn, Sarah; Virtanen, Sannakaisa

2015-02-01

A TiO2 nanoparticle coating was prepared on a biomedical Ti-6Al-4V alloy using "spin-coating" technique with a colloidal suspension of TiO2 nanopowders with the aim to optimize the surface morphology (e.g., roughness) for improved biocompatibility. The influence of a TiO2 nanoparticle (NP) coating on the corrosion behavior, metal ion release, and biomimetic apatite formation was studied in DMEM, at 37.5 °C with a continuous supply of 5% CO2. Electrochemical impedance spectroscopy measurements indicate a formation of a new layer on the surface of the NP-coated sample upon 28 days immersion in DMEM. Scanning electron microscopy (SEM) and X-ray spectroscopy confirm that the surface of the NP-coated Ti-6Al-4V shows a complete coverage by a Ca-phosphate layer in contrast to the non-coated Ti-6Al-4V alloy. Hence, the TiO2-NP coating strongly enhances biomimetic apatite formation on the alloy surface. In addition, the TiO2-NP coating can efficiently reduce Al-release from the alloy, for which the bare Ti-6Al-4V alloy is significant for at least 28 days of immersion in DMEM.

Innovative micro-textured hydroxyapatite and poly(l-lactic)-acid polymer composite film as a flexible, corrosion resistant, biocompatible, and bioactive coating for Mg implants.

PubMed

Kim, Sae-Mi; Kang, Min-Ho; Kim, Hyoun-Ee; Lim, Ho-Kyung; Byun, Soo-Hwan; Lee, Jong-Ho; Lee, Sung-Mi

2017-12-01

The utility of a novel ceramic/polymer-composite coating with a micro-textured microstructure that would significantly enhance the functions of biodegradable Mg implants is demonstrated here. To accomplish this, bioactive hydroxyapatite (HA) micro-dots can be created by immersing a Mg implant with a micro-patterned photoresist surface in an aqueous solution containing calcium and phosphate ions. The HA micro-dots can then be surrounded by a flexible poly(l-lactic)-acid (PLLA) polymer using spin coating to form a HA/PLLA micro-textured coating layer. The HA/PLLA micro-textured coating layer showed an excellent corrosion resistance when it was immersed in a simulated body fluid (SBF) solution and good biocompatibility, which was assessed by in vitro cell tests. In addition, the HA/PLLA micro-textured coating layer had high deformation ability, where no apparent changes in the coating layer were observed even after a 5% elongation, which would be unobtainable using HA and PLLA coating layers; furthermore, this allowed the mechanically-strained Mg implant with the HA/PLLA micro-textured coating layer to preserve its excellent corrosion resistance and biocompatibility in vitro. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultra-Porous Nanoparticle Networks: A Biomimetic Coating Morphology for Enhanced Cellular Response and Infiltration

PubMed Central

Nasiri, Noushin; Ceramidas, Anthony; Mukherjee, Shayanti; Panneerselvan, Anitha; Nisbet, David R.; Tricoli, Antonio

2016-01-01

Orthopedic treatments are amongst the most common cause of surgery and are responsible for a large share of global healthcare expenditures. Engineering materials that can hasten bone integration will improve the quality of life of millions of patients per year and reduce associated medical costs. Here, we present a novel hierarchical biomimetic coating that mimics the inorganic constituent of mammalian bones with the aim of improving osseointegration of metallic implants. We exploit the thermally-driven self-organization of metastable core-shell nanoparticles during their aerosol self-assembly to rapidly fabricate robust, ultra-porous nanoparticle networks (UNN) of crystalline hydroxyapatite (HAp). Comparative analysis of the response of osteoblast cells to the ultra-porous nanostructured HAp surfaces and to the spin coated HAp surfaces revealed superior osseointegrative properties of the UNN coatings with significant cell and filopodia infiltration. This flexible synthesis approach for the engineering of UNN HAp coatings on titanium implants provides a platform technology to study the bone-implant interface for improved osseointegration and osteoconduction. PMID:27076035

Raman and nuclear magnetic resonance investigation of alkali metal vapor interaction with alkene-based anti-relaxation coating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tretiak, O. Yu., E-mail: otretiak@genphys.ru; Balabas, M. V.; Blanchard, J. W.

2016-03-07

The use of anti-relaxation coatings in alkali vapor cells yields substantial performance improvements compared to a bare glass surface by reducing the probability of spin relaxation in wall collisions by several orders of magnitude. Some of the most effective anti-relaxation coating materials are alpha-olefins, which (as in the case of more traditional paraffin coatings) must undergo a curing period after cell manufacturing in order to achieve the desired behavior. Until now, however, it has been unclear what physicochemical processes occur during cell curing, and how they may affect relevant cell properties. We present the results of nondestructive Raman-spectroscopy and magnetic-resonancemore » investigations of the influence of alkali metal vapor (Cs or K) on an alpha-olefin, 1-nonadecene coating the inner surface of a glass cell. It was found that during the curing process, the alkali metal catalyzes migration of the carbon-carbon double bond, yielding a mixture of cis- and trans-2-nonadecene.« less

Study of Asorption Kinetics of Surfactants onto Polyethersulfone Membrane Surface Using QCM-D

USDA-ARS?s Scientific Manuscript database

The adsorption kinetics of surfactants onto the crystal surface spin-coated with a thin layer of a model membrane material, polyethersulfone was monitored through measurements of frequency and dissipation shifts simultaneously using a quartz crystal microbalance with dissipation (QCM-D) device. In ...

Effects of sintering temperature on the pyrochlore phase in PZT nanotubes and their transformation to the perovskite phase by coating with PbO multilayers.

PubMed

Han, Jin Kyu; Choi, Yong Chan; Jeon, Do Hyen; Lee, Min Ku; Bu, Sang Don

2014-11-01

We report the phase evolution of Pb(Zr0.52Ti0.48)O3 nanotubes (PZT-NTs), from the pyrochlore to perovskite phase, with an outer diameter of about 420 nm and a wall thickness of about 10 nm. The PZT-NTs were fabricated in pores of porous anodic alumina membrane (PAM) using a spin coating of PZT sol-gel solution and subsequent annealing at 500-700 degrees C in oxygen gas. The pyrochlore phase was found to be formed at 500 degrees C, and also found not to be transformed into the perovskite phase, even though annealing was performed at higher temperatures to 700 degrees C. Elementary distribution analysis of PZT-NTs embedded in PAM reveal that Pb diffusion from nanotubes into pore walls of PAM is one of the main reasons. By employing firstly an additional PbO coating on the pyrochlore nanotubes and then subsequent annealing at 700 degrees C, we have successfully achieved an almost pure perovskite phase in nanotubes. These results suggest that PbO acts as a Pb-compensation agent in the Pb- deficient PZT-NTs. Moreover, our method can be used in the synthesis of all metal-oxide materials, including volatile elements.

Effect of TiO{sub 2} thickness on nanocomposited aligned ZnO nanorod/TiO{sub 2} for dye-sensitized solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saurdi, I., E-mail: saurdy788@gmail.com; Ishak, A.; UiTM Sarawak Kampus Kota Samarahan Jalan Meranek, Sarawak

2016-07-06

The TiO{sub 2} films were deposited on glass substrate at different thicknesses with different deposition frequencies (1, 2, 3 and 4 times) using spin coating technique and their structural properties were investigated. Subsequently, the nanocomposited aligned ZnO nanorods and TiO{sub 2} were formed by deposited the TiO{sub 2} on top of aligned ZnO Nanorod on ITO-coated glass at different thicknesses using the same method of TiO{sub 2} deposited on glass substrate. The nanocomposited aligned ZnO nanorod/TiO{sub 2} were coated with different thicknesses of 900µm, 1815µm, 2710µm, 3620µm and ZnO without TiO{sub 2}. The dye-sensitized solar cells were fabricated from themore » nanocomposited aligned ZnO nanorod/TiO{sub 2} with thickness of 900µm, 1815µm, 2710µm and 3620µm and ZnO without TiO{sub 2} and their photovoltaic properties of the DSSCs were investigated. From the solar simulator measurement the solar energy conversion efficiency (η) of 2.543% under AM 1.5 was obtained for the ZnO nanorod/TiO{sub 2} photoanode-2710µm Dye-Sensitized solar cell.« less

[The effect of methyl-containing supplements during pregnancy on the phenotypic modification of offspring hair color in rats].

PubMed

Prasolova, L A; Trut, L N; Os'kina, I N; Gulevich, R G; Pliusnina, I Z; Vsevolodov, E B; Latypov, I F

2006-01-01

The effect of methyl supplements to the diet of pregnant homozygous (AAHH) female rats with agouti coat color mated with homozygous (aahh) males on the phenotypic modification of the coat color of their heterozygous offspring (AaHh) has been studied. Comparative morphological analysis of the main parameters of hair that determine coat color, including the total length of hairs of different types and the length of the upper black (eumelanin) and light (pheomelanin) parts of awn hairs has been performed. The pattern of pigment granule distribution among hair layers has been analyzed. The melanin content of the hair has been determined using electron spin resonance (ESR). Although all offspring have a typical agouti coat color (alternating black and light portions of hair), 39% of them have a darker coat color than control and other experimental rats have. The main differences between the offspring with darkened and standard coat colors are accounted for by the ratio between the eumelanin and pheomelanin portions of awn hairs. In darkened offspring, this ratio is significantly higher than in control rats. The possible mechanisms of the phenotypic modification of agouti coat color in experimental animals are discussed.

Ethane-Bridged Bisporphyrin Conformational Changes As an Effective Analytical Tool for Nonenzymatic Detection of Urea in the Physiological Range.

PubMed

Buccolieri, Alessandro; Hasan, Mohammed; Bettini, Simona; Bonfrate, Valentina; Salvatore, Luca; Santino, Angelo; Borovkov, Victor; Giancane, Gabriele

2018-06-05

Conformational switching induced in ethane-bridged bisporphyrins was used as a sensitive transduction method for revealing the presence of urea dissolved in water via nonenzymatic approach. Bisporphyrins were deposited on solid quartz slides by means of the spin-coating method. Molecular conformations of Zn and Ni monometalated bis-porphyrins were influenced by water solvated urea molecules and their fluorescence emission was modulated by the urea concentration. Absorption, fluorescence and Raman spectroscopies allowed the identification of supramolecular processes, which are responsible for host-guest interaction between the active layers and urea molecules. A high selectivity of the sensing mechanism was highlighted upon testing the spectroscopic responses of bis-porphyrin films to citrulline and glutamine used as interfering agents. Additionally, potential applicability was demonstrated by quantifying the urea concentration in real physiological samples proposing this new approach as a valuable alternative analytical procedure to the traditionally used enzymatic methods.

Spectroscopic ellipsometry data inversion using constrained splines and application to characterization of ZnO with various morphologies

NASA Astrophysics Data System (ADS)

Gilliot, Mickaël; Hadjadj, Aomar; Stchakovsky, Michel

2017-11-01

An original method of ellipsometric data inversion is proposed based on the use of constrained splines. The imaginary part of the dielectric function is represented by a series of splines, constructed with particular constraints on slopes at the node boundaries to avoid well-know oscillations of natural splines. The nodes are used as fit parameters. The real part is calculated using Kramers-Kronig relations. The inversion can be performed in successive inversion steps with increasing resolution. This method is used to characterize thin zinc oxide layers obtained by a sol-gel and spin-coating process, with a particular recipe yielding very thin layers presenting nano-porosity. Such layers have particular optical properties correlated with thickness, morphological and structural properties. The use of the constrained spline method is particularly efficient for such materials which may not be easily represented by standard dielectric function models.

Preparation of anatase TiO2 thin film by low temperature annealing as an electron transport layer in inverted polymer solar cells

NASA Astrophysics Data System (ADS)

Noh, Hongche; Oh, Seong-Geun; Im, Seung Soon

2015-04-01

To prepare the anatase TiO2 thin films on ITO glass, amorphous TiO2 colloidal solution was synthesized through the simple sol-gel method by using titanium (IV) isopropoxide as a precursor. This amorphous TiO2 colloidal solution was spread on ITO glass by spin-coating, then treated at 450 °C to obtain anatase TiO2 film (for device A). For other TiO2 films, amorphous TiO2 colloidal solution was treated through solvothermal process at 180 °C to obtain anatase TiO2 colloidal solution. This anatase TiO2 colloidal solution was spread on ITO glass by spin coating, and then annealed at 200 °C (for device B) and 130 °C (for device C), respectively. The average particle size of amorphous TiO2 colloidal solution was about 1.0 nm and that of anatase TiO2 colloidal solution was 10 nm. The thickness of TiO2 films was about 15 nm for all cases. When inverted polymer solar cells were fabricated by using these TiO2 films as an electron transport layer, the device C showed the highest PCE (2.6%) due to the lack of defect, uniformness and high light absorbance of TiO2 films. The result of this study can be applied for the preparation of inverted polymer solar cell using TiO2 films as a buffer layer at low temperature on plastic substrate by roll-to roll process.

Biomolecule detection using wheatstone bridge giant magnetoresistance (GMR) sensors based on CoFeB spin-valve thin film

NASA Astrophysics Data System (ADS)

Elda Swastika, P.; Antarnusa, G.; Suharyadi, E.; Kato, T.; Iwata, S.

2018-04-01

A potential wheatstone bridge giant magnetoresistance (GMR) biosensor have been successfully developed for biomolecule detection. [IrMn(10 nm)/CoFe(3 nm)/Cu(2.2 nm)/CoFeB(10 nm)] spin-valve structure has been chosen as the magnetic sensing surface, showing a magnetoresistance (MR) of 6% fabricated by DC magnetron sputtering method. The Fe3O4 magnetic nanoparticles used as biomolecular labels (nanotags) was synthesized by co-precipitation method, exhibiting soft magnetic behavior with saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) is 77.2 emu/g, 7.8 emu/g and 51 Oe, respectively. The X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images showed that Fe3O4 was well crystallized and grew in their inverse spinel structure, highly uniform morphology with an average grain size was about 20 nm. Fe3O4 was coated with polyethylene-glycol (PEG)-4000 for surface functionalization. Detection of biomolecule such as formalin, gelatin from bovine-skin and porcine-skin were dispersed in ethanol at room temperature. Induction would cause a shift in output voltage with a minimum delta output voltage (ΔV) 4.937 mV (10%) for formalin detection, 2.268 mV (7%) for bovine-skin gelatin and 2.943 mV (7%) for porcine-skin gelatin detection. The ΔV of the wheatstone bridge in real-time measurement decrease by increase in biomolecules concentration. The change of ΔV with various concentration of biomolecule indicates that the spin-valve thin film with wheatstone-bridge circuit is potential as a biosensor.

Optical limiting in gelatin stabilized Cu-PVP nanocomposite colloidal suspension

NASA Astrophysics Data System (ADS)

Tamgadge, Y. S.; Gedam, P. P.; Thakare, N. B.; Talwatkar, S. S.; Sunatkari, A. L.; Muley, G. G.

2018-05-01

This article illustrates investigations on optical limiting properties of Cu-PVP nanocomposite colloidal suspension. Gelatin stabilized Cu nanoparticles have been synthesized using chemical reduction method and thin films in PVP matrix have been obtained using spin coating technique. Thin films have been characterized by X-ray diffraction (XRD), Ultraviolet-visible (UV-vis) spectroscopy, etc. for structural and linear optical studies. Optical limiting properties of Colloidal Cu-PVP nanocomposites have been investigated at 808 nm diode CW laser. Minimum optical limiting threshold was found for GCu3-PVP nanocomposites sample. The strong optical limiting is thermal in origin as CW laser is used and effects are attributed to thermal lensing effect.

Preparation and atomic force microscopy of CTAB stabilized polythiophene nanoparticles thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graak, Pinki; Devi, Ranjna; Kumar, Dinesh

2016-05-06

Polythiophene nanoparticles were synthesized by iron catalyzed oxidative polymerization method. Polythiophene formation was detected by UV-Visible spectroscopy with λmax 375nm. Thin films of CTAB stabilized polythiophene nanoparticles was deposited on n-type silicon wafer by spin coating technique at 3000rpm in three cycles. Thickness of the thin films was computed as 300-350nm by ellipsometry. Atomic force micrscopyrevealws the particle size of polymeric nanoparticles in the range of 30nm to 100nm. Roughness of thinfilm was also analyzed from the atomic force microscopy data by Picoimage software. The observed RMS value lies in the range of 6 nm to 12 nm.

Organosilicon derivatives of BTBT for monolayer organic field effect transistors

NASA Astrophysics Data System (ADS)

Agina, Elena V.; Polinskaya, Marina S.; Trul, Askold A.; Chekusova, Viktoria P.; Sizov, Alexey S.; Borshchev, Oleg V.; Ponomarenko, Sergey A.

2017-08-01

Synthesis of novel organosilicon derivatives of [1]benzothieno[3,2-b][1]-benzothiophene (BTBT) linked though flexible aliphatic spacers to a disiloxane anchor group is reported. They were successfully used in monolayer OFETs with the charge carrier mobilities up to 0.02 cm2 /Vs, threshold voltage close to 0 V and On/Off ratio up to 10,000. Influence of the chemical structure of the molecules synthesized on the morphology, molecular 2D ordering in the monolayers and their semiconducting properties is considered. The effect of different methods of the ultrathin semiconducting layer preparation, such as Langmuir-Blodgett, Langmuir-Schaefer, spin coating or doctor blade, on the OFET performance is discussed.

Effect of halogenation on the nonlinear optical properties of porthyrin and substituted porphyrins

NASA Technical Reports Server (NTRS)

Cardelino, Beatriz H.; Moore, Craig E.; Benloss, Angela; Thompson, Albert N., Jr.; Richards, Rosalie A.; Roney, Celeste A.; Sanghadasa, Mohan

1998-01-01

The effect that fluorine and chlorine substitution has on the nonlinear optical properties of porphyrin, tetramethylporphyrin and tetraphenylporphyrin has been theoretically studied. The calculations of nonlinear optical properties have been obtained by performing finite-field calculations on structures determined by semiempirical methods. In addition, tetra(p-chlorophenyl)porphyrin and tetra(p-bromophenyl)porphyrin were synthesized by the condensation of pyrrol and the appropriate aldehyde. Thin films of polymethylmethacrylate were obtained containing these materials, by spin coating onto glass substrates. The films were characterized by third-harmonic generation. It was determined that the experimental conditions enhance the third-order polarizability of the tetraphenylporphyrins by a factor of about 1.6.

Manufacturing techniques for gyroscopes in gravity probe B

NASA Technical Reports Server (NTRS)

Rasquin, J. R.

1976-01-01

The design of the fused silica gyroscope configuration is presented. The first gyroscope was made for erection and spin tests only and does not contain the angle readout loops necessary for a functioning experimental gyroscope. The rotor ball described is not coated with the ultimate material, niobium, but instead with a sandwich of titanium, cooper, and titanium for spin-up test purposes. Background, historical information, manufacturing procedures, and sketches for this gyroscope are included to provide a better understanding of the device and the techniques and special tools required to manufacture a fused silica gyroscope to the required specifications.

Gd-functionalised Au nanoparticles as targeted contrast agents in MRI: relaxivity enhancement by polyelectrolyte coating.

PubMed

Warsi, Muhammad Farooq; Adams, Ralph W; Duckett, Simon B; Chechik, Victor

2010-01-21

Monolayer-protected, Gd(3+)-functionalised gold nanoparticles with enhanced spin-lattice relaxivity (r(1)) were prepared; adsorption of polyelectrolytes on these materials further increased r(1) and ligand exchange with a biotin-derivatised disulfide led to a prototype avidin-targeted contrast agent.

Passivation of pigment particles for thermal control coatings

NASA Technical Reports Server (NTRS)

Sancier, K. M.; Morrison, S. R.; Farley, E. P.

1975-01-01

The preparation of a matrix of 48 samples consisting of pigments and pigmented paints is described. The results obtained from testing these samples by electron spin resonance and by in situ spectral reflectance measurements in space simulation tests are presented. Conclusions and recommendations for further research are given.

Lattice model for self-assembly with application to the formation of cytoskeletal-like structures

NASA Astrophysics Data System (ADS)

Stewman, Shannon F.; Dinner, Aaron R.

2007-07-01

We introduce a stochastic approach for self-assembly in systems far from equilibrium. The building blocks are represented by a lattice of discrete variables (Potts-like spins), and physically meaningful mechanisms are obtained by restricting transitions through spatially local rules based on experimental data. We use the method to study nucleation of filopodia-like bundles in a system consisting of purified actin, fascin, actin-related protein 2/3 , and beads coated with Wiskott-Aldrich syndrome protein. Consistent with previous speculation based on static experimental images, we find that bundles derive from Λ -precursor-like patterns of spins on the lattice. The ratcheting of the actin network relative to the surface that represents beads plays an important role in determining the number and orientation of bundles due to the fact that branching is the primary means for generating barbed ends pointed in directions that allow rapid filament growth. By enabling the de novo formation of coexisting morphologies without the computational cost of explicit representation of proteins, the approach introduced complements earlier models of cytoskeletal behavior in vitro and in vivo.

Sub-nanometer Atomic Layer Deposition for Spintronics in Magnetic Tunnel Junctions Based on Graphene Spin-Filtering Membranes

PubMed Central

2014-01-01

We report on the successful integration of low-cost, conformal, and versatile atomic layer deposited (ALD) dielectric in Ni–Al2O3–Co magnetic tunnel junctions (MTJs) where the Ni is coated with a spin-filtering graphene membrane. The ALD tunnel barriers, as thin as 0.6 nm, are grown layer-by-layer in a simple, low-vacuum, ozone-based process, which yields high-quality electron-transport barriers as revealed by tunneling characterization. Even under these relaxed conditions, including air exposure of the interfaces, a significant tunnel magnetoresistance is measured highlighting the robustness of the process. The spin-filtering effect of graphene is enhanced, leading to an almost fully inversed spin polarization for the Ni electrode of −42%. This unlocks the potential of ALD for spintronics with conformal, layer-by-layer control of tunnel barriers in magnetic tunnel junctions toward low-cost fabrication and down-scaling of tunnel resistances. PMID:24988469

Magnetization switching in ferromagnets by adsorbed chiral molecules without current or external magnetic field.

PubMed

Ben Dor, Oren; Yochelis, Shira; Radko, Anna; Vankayala, Kiran; Capua, Eyal; Capua, Amir; Yang, See-Hun; Baczewski, Lech Tomasz; Parkin, Stuart Stephen Papworth; Naaman, Ron; Paltiel, Yossi

2017-02-23

Ferromagnets are commonly magnetized by either external magnetic fields or spin polarized currents. The manipulation of magnetization by spin-current occurs through the spin-transfer-torque effect, which is applied, for example, in modern magnetoresistive random access memory. However, the current density required for the spin-transfer torque is of the order of 1 × 10 6  A·cm -2 , or about 1 × 10 25 electrons s -1 cm -2 . This relatively high current density significantly affects the devices' structure and performance. Here we demonstrate magnetization switching of ferromagnetic thin layers that is induced solely by adsorption of chiral molecules. In this case, about 10 13 electrons per cm 2 are sufficient to induce magnetization reversal. The direction of the magnetization depends on the handedness of the adsorbed chiral molecules. Local magnetization switching is achieved by adsorbing a chiral self-assembled molecular monolayer on a gold-coated ferromagnetic layer with perpendicular magnetic anisotropy. These results present a simple low-power magnetization mechanism when operating at ambient conditions.

Magnetization switching in ferromagnets by adsorbed chiral molecules without current or external magnetic field

PubMed Central

Ben Dor, Oren; Yochelis, Shira; Radko, Anna; Vankayala, Kiran; Capua, Eyal; Capua, Amir; Yang, See-Hun; Baczewski, Lech Tomasz; Parkin, Stuart Stephen Papworth; Naaman, Ron; Paltiel, Yossi

2017-01-01

Ferromagnets are commonly magnetized by either external magnetic fields or spin polarized currents. The manipulation of magnetization by spin-current occurs through the spin-transfer-torque effect, which is applied, for example, in modern magnetoresistive random access memory. However, the current density required for the spin-transfer torque is of the order of 1 × 106 A·cm−2, or about 1 × 1025 electrons s−1 cm−2. This relatively high current density significantly affects the devices' structure and performance. Here we demonstrate magnetization switching of ferromagnetic thin layers that is induced solely by adsorption of chiral molecules. In this case, about 1013 electrons per cm2 are sufficient to induce magnetization reversal. The direction of the magnetization depends on the handedness of the adsorbed chiral molecules. Local magnetization switching is achieved by adsorbing a chiral self-assembled molecular monolayer on a gold-coated ferromagnetic layer with perpendicular magnetic anisotropy. These results present a simple low-power magnetization mechanism when operating at ambient conditions. PMID:28230054

Determination of average refractive index of spin coated DCG films for HOE fabrication

NASA Technical Reports Server (NTRS)

Kim, T. J.; Campbell, Eugene W.; Kostuk, Raymond K.

1993-01-01

The refractive index of holographic emulsions is an important parameter needed for designing holographic optical elements (HOE's). Theoretical calculations of the accuracy required for the refractive index and thickness of emulsions needed to meet predetermined Bragg angle conditions are presented. A modified interferometric method is used to find average refractive index of the unexposed and the developed dichromated gelatin holographic films. Slanted transmission HOE's are designed considering the index and thickness variations, and used to verify the index measurement results. The Brewster angle method is used to measure surface index of the unexposed and the developed films. The differences between average index and surface index are discussed. Theoretical calculation of the effects of index variation on diffraction efficiency, and experimental results for index modulation variation caused by process changes are also presented.

Humidity Sensing Properties of Paper Substrates and Their Passivation with ZnO Nanoparticles for Sensor Applications

PubMed Central

Niarchos, Georgios; Dubourg, Georges; Afroudakis, Georgios; Georgopoulos, Markos; Tsouti, Vasiliki; Makarona, Eleni; Crnojevic-Bengin, Vesna; Tsamis, Christos

2017-01-01

In this paper, we investigated the effect of humidity on paper substrates and propose a simple and low-cost method for their passivation using ZnO nanoparticles. To this end, we built paper-based microdevices based on an interdigitated electrode (IDE) configuration by means of a mask-less laser patterning method on simple commercial printing papers. Initial resistive measurements indicate that a paper substrate with a porous surface can be used as a cost-effective, sensitive and disposable humidity sensor in the 20% to 70% relative humidity (RH) range. Successive spin-coated layers of ZnO nanoparticles then, control the effect of humidity. Using this approach, the sensors become passive to relative humidity changes, paving the way to the development of ZnO-based gas sensors on paper substrates insensitive to humidity. PMID:28273847

Some studies on TiO2 films deposited by sol-gel technique

NASA Astrophysics Data System (ADS)

Narasimha Rao, K.; Vishwas, M.; Kumar Sharma, Sudhir; Arjuna Gowda, K. V.

2008-08-01

TiO2 films are extensively used in various applications including optical multi-layers, sensors, photo catalysis, environmental purification, and solar cells etc. These are prepared by both vacuum and non-vacuum methods. In this paper, we present the results on TiO2 thin films prepared by a sol-gel spin coating process in non-aqueous solvent. Titanium isopropoxide is used as TiO2 precursor. The films were annealed at different temperatures up to 3000 C for 5 hours in air. The influence of the various deposition parameters like spinning speed, spinning time and annealing temperature on the thickness of the TiO2 films has been studied. The variation of film thickness with time in ambient atmosphere was also studied. The optical, structural and morphological characteristics were investigated by optical transmittance-reflectance measurements, X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The refractive index and extinction coefficient of the films were determined by envelope technique and spectroscopic ellipsometry. TiO2 films exhibited high transparency (92%) in the visible region with a refractive index of 2.04 at 650 nm. The extinction coefficient was found to be negligibly small. The X-ray diffraction analysis showed that the TiO2 film deposited on glass substrate changes from amorphous to crystalline (anatase) phase with annealing temperature above 2500 C. SEM results show that the deposited films are uniform and crack free.

Growth of CH3NH3PbI3 Perovskite on Stainless Steel Substrate Layered by ZnO Nanoparticles Using One-Step Spin Coating Route

NASA Astrophysics Data System (ADS)

Fuad, A.; Fibriyanti, A. A.; Mufti, N.; Taufiq, A.; Maryam, S.; Hidayat, N.

2018-04-01

In this work, we report the preparation of CH3NH3PbI3 perovskite using one-step spin coating route for solar cell application. CH3NH3I• PbI2•DMF•DMSO complexes were coated on stainless steel as a subtrate layered by ZnO nanoparticles as an electron transport layer. To obtain samples with a special performance, we annealed the samples at a temperature of 100, 120, and 140°C for 10 minutes. The samples were then characterized by means of XRD, SEM/EDX, and Spectroscopic Ellipsometry. The analysis of XRD data presented that the CH3NH3PbI3 perovskites were successfully prepared and crystallized in tetragonal structure confirming from crystalline planes (110) and (220). Meanwhile, the particle size of the samples prepared at a temperature of 100, 120, and 140°C presented 42.96, 54.73, and 55.19 nm, respectively with coincide with the SEM images. The results indicated that the increase in temperature during synthesis influenced the particle growth. Furthermore, the characterization using Spectroscopic Ellipsometry exhibited that the CH3NH3PbI3 successfully layered on the substrate sizing nano metric scale that open high opportunity to be applied to solar cells with high performance.

Development of a highly transparent superamphiphobic plastic sheet by nanoparticle and chemical coating.

PubMed

Wong, Ten It; Wang, Hao; Wang, Fuke; Sin, Sau Leng; Quan, Cheng Gen; Wang, Shi Jie; Zhou, Xiaodong

2016-04-01

A highly transparent superamphiphobic plastic sheet was developed. The plastic sheet polymethyl methacrylate (PMMA) was spin-coated on a glass substrate. Synthesized silica nanoparticles were sprayed on PMMA, followed by fluorosilane drop-coating. The results of contact angle measurements show that the developed PMMA sheet has superamphiphobic properties with high advancing contact angles for water (154°), toluene (139°), and silicone oil (132.9°). The amphiphobicity of the plastic sheet can be tuned by the surface coverage of the silica nanoparticles distributed on the PMMA surface. The surface coverage of the nanoparticles on our PMMA sheet is about 20%, and it agrees with our contact angle calculations for the sheet with and without nanoparticles. Copyright © 2016 Elsevier Inc. All rights reserved.

Improved BC method of Compomat G4 for expression of BCs twice from whole blood in top and top bags.

PubMed

Deng, Xiao-Yan; Wu, Xiao-Man; Zhao, Yang; Luo, Hong; Jia, Hong-Yun; Wang, Zhong-Ying; He, Bo; Wang, Chuan-Xi

2011-05-01

The aim of this paper was to evaluate an improved buffy coat (BC) method of Compomat G4 for automated expression of BCs twice from whole blood (WB) in top and top (T&T) bags. WB was separated using hard spin centrifugation (2,988g, 10 min) into layers of blood components by specific gravity, and different components were subsequently expressed into satellite bags in the T&T system using the manual BC method, the conventional BC method of G4, and our improved BC method of G4. In the improved BC method, an accessorial device we have named a 'gravity press' was designed and installed on the top flat of G4 to produce gravitational pressure on the plasma bag so as to exclude air and some of plasma to the upper compartment of the slide after BCs were expressed for the first time. The residual BCs in the upper compartment were expressed a second time by extending the upper press once more. All of the pooled BCs were centrifuged by soft spin (402g, 10 min) and upper platelet-rich supernatant was manually expressed into a platelet container by the plasma extractor. In vitro studies of blood components and pooled platelet concentrates (PCs) revealed no significant differences in BC blood components and platelet recovery of pooled platelets (61 ± 9 vs. 60 ± 7%, n = 12, p > 0.05) between the improved BC method and the conventional BC method; all components met our specifications for blood products. We suggest that the new BC method for use of T&T bags may improve the collection of BCs.

Microfabrication of plastic-PDMS microfluidic devices using polyimide release layer and selective adhesive bonding

DOE PAGES

Wang, Shuyu; Yu, Shifeng; Lu, Ming; ...

2017-03-15

In this study, we present an improved method to bond poly(dimethylsiloxane) (PDMS) with polyimide (PI) to develop flexible substrate microfluidic devices. The PI film was separately fabricated on a silicon wafer by spin coating followed by thermal treatment to avoid surface unevenness of the flexible substrate. In this way, we could also integrate flexible substrate into standard micro-electromechanical systems (MEMS) fabrication. Meanwhile, the adhesive epoxy was selectively transferred to the PDMS microfluidic device by a stamp-and-stick method to avoid epoxy clogging the microfluidic channels. To spread out the epoxy evenly on the transferring substrate, we used superhydrophilic vanadium oxide filmmore » coated glass as the transferring substrate. After the bonding process, the flexible substrate could easily be peeled off from the rigid substrate. Contact angle measurement was used to characterize the hydrophicity of the vanadium oxide film. X-ray photoelectron spectroscopy analysis was conducted to study the surface of the epoxy. We further evaluated the bonding quality by peeling tests, which showed a maximum bonding strength of 100 kPa. By injecting with black ink, the plastic microfluidic device was confirmed to be well bonded with no leakage for a day under 1 atm. Finally, this proposed versatile method could bond the microfluidic device and plastic substrate together and be applied in the fabrication of some biosensors and lab-on-a-chip systems.« less

Rapid prototyping of microfluidic systems using a PDMS/polymer tape composite.

PubMed

Kim, Jungkyu; Surapaneni, Rajesh; Gale, Bruce K

2009-05-07

Rapid prototyping of microfluidic systems using a combination of double-sided tape and PDMS (polydimethylsiloxane) is introduced. PDMS is typically difficult to bond using adhesive tapes due to its hydrophobic nature and low surface energy. For this reason, PDMS is not compatible with the xurography method, which uses a knife plotter and various adhesive coated polymer tapes. To solve these problems, a PDMS/tape composite was developed and demonstrated in microfluidic applications. The PDMS/tape composite was created by spinning it to make a thin layer of PDMS over double-sided tape. Then the PDMS/tape composite was patterned to create channels using xurography, and bonded to a PDMS slab. After removing the backing paper from the tape, a complete microfluidic system could be created by placing the construct onto nearly any substrate; including glass, plastic or metal-coated glass/silicon substrates. The bond strength was shown to be sufficient for the pressures that occur in typical microfluidic channels used for chemical or biological analysis. This method was demonstrated in three applications: standard microfluidic channels and reactors, a microfluidic system with an integrated membrane, and an electrochemical biosensor. The PDMS/tape composite rapid prototyping technique provides a fast and cost effective fabrication method and can provide easy integration of microfluidic channels with sensors and other components without the need for a cleanroom facility.

Microfabrication of plastic-PDMS microfluidic devices using polyimide release layer and selective adhesive bonding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Shuyu; Yu, Shifeng; Lu, Ming

In this study, we present an improved method to bond poly(dimethylsiloxane) (PDMS) with polyimide (PI) to develop flexible substrate microfluidic devices. The PI film was separately fabricated on a silicon wafer by spin coating followed by thermal treatment to avoid surface unevenness of the flexible substrate. In this way, we could also integrate flexible substrate into standard micro-electromechanical systems (MEMS) fabrication. Meanwhile, the adhesive epoxy was selectively transferred to the PDMS microfluidic device by a stamp-and-stick method to avoid epoxy clogging the microfluidic channels. To spread out the epoxy evenly on the transferring substrate, we used superhydrophilic vanadium oxide filmmore » coated glass as the transferring substrate. After the bonding process, the flexible substrate could easily be peeled off from the rigid substrate. Contact angle measurement was used to characterize the hydrophicity of the vanadium oxide film. X-ray photoelectron spectroscopy analysis was conducted to study the surface of the epoxy. We further evaluated the bonding quality by peeling tests, which showed a maximum bonding strength of 100 kPa. By injecting with black ink, the plastic microfluidic device was confirmed to be well bonded with no leakage for a day under 1 atm. Finally, this proposed versatile method could bond the microfluidic device and plastic substrate together and be applied in the fabrication of some biosensors and lab-on-a-chip systems.« less

Metal-oxide assisted surface treatment of polyimide gate insulators for high-performance organic thin-film transistors.

PubMed

Kim, Sohee; Ha, Taewook; Yoo, Sungmi; Ka, Jae-Won; Kim, Jinsoo; Won, Jong Chan; Choi, Dong Hoon; Jang, Kwang-Suk; Kim, Yun Ho

2017-06-14

We developed a facile method for treating polyimide-based organic gate insulator (OGI) surfaces with self-assembled monolayers (SAMs) by introducing metal-oxide interlayers, called the metal-oxide assisted SAM treatment (MAST). To create sites for surface modification with SAM materials on polyimide-based OGI (KPI) surfaces, the metal-oxide interlayer, here amorphous alumina (α-Al 2 O 3 ), was deposited on the KPI gate insulator using spin-coating via a rapid sol-gel reaction, providing an excellent template for the formation of a high-quality SAM with phosphonic acid anchor groups. The SAM of octadecylphosphonic acid (ODPA) was successfully treated by spin-coating onto the α-Al 2 O 3 -deposited KPI film. After the surface treatment by ODPA/α-Al 2 O 3 , the surface energy of the KPI thin film was remarkably decreased and the molecular compatibility of the film with an organic semiconductor (OSC), 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-C 10 ), was increased. Ph-BTBT-C 10 molecules were uniformly deposited on the treated gate insulator surface and grown with high crystallinity, as confirmed by atomic force microscopy (AFM) and X-ray diffraction (XRD) analysis. The mobility of Ph-BTBT-C 10 thin-film transistors (TFTs) was approximately doubled, from 0.56 ± 0.05 cm 2 V -1 s -1 to 1.26 ± 0.06 cm 2 V -1 s -1 , after the surface treatment. The surface treatment of α-Al 2 O 3 and ODPA significantly decreased the threshold voltage from -21.2 V to -8.3 V by reducing the trap sites in the OGI and improving the interfacial properties with the OSC. We suggest that the MAST method for OGIs can be applied to various OGI materials lacking reactive sites using SAMs. It may provide a new platform for the surface treatment of OGIs, similar to that of conventional SiO 2 gate insulators.

Efficient semitransparent perovskite solar cells for 23.0%-efficiency perovskite/silicon four-terminal tandem cells

DOE PAGES

Chen, Bo; Bai, Yang; Yu, Zhengshan; ...

2016-07-19

Here, we have investigated semi-transparent perovskite solar cells and infrared enhanced silicon heterojunction cells for high-efficiency tandem devices. A semi-transparent metal electrode with good electrical conductivity and optical transparency has been fabricated by thermal evaporation of 7 nm of Au onto a 1-nm-thick Cu seed layer. For this electrode to reach its full potential, MAPbI3 thin films were formed by a modified one-step spin-coating method, resulting in a smooth layer that allowed the subsequent metal thin film to remain continuous. The fabricated semi-transparent perovskite solar cells demonstrated 16.5% efficiency under one-sun illumination, and were coupled with infrared-enhanced silicon heterojunction cellsmore » tuned specifically for perovskite/Si tandem devices. A double-layer antireflection coating at the front side and MgF2 reflector at rear side of the silicon heterojunction cells reduced parasitic absorption of near-infrared light, leading to 6.5% efficiency after filtering with a perovskite device and 23.0% summed efficiency for the perovskite/Si tandem device.« less

Solution-processed nanocrystalline PbS on paper substrate with pencil traced electrodes as visible photodetector

NASA Astrophysics Data System (ADS)

Vankhade, Dhaval; Chaudhuri, Tapas K.

2018-04-01

Paper-based PbS photodetector sensitive in the visible spectrum is reported. Nanocrystalline PbS-on-paper devices are fabricated by a spin coating method on white paper (300 GSM) from a methanolic precursor solution. Photodetector cells of gap 0.2 cm and length 0.5 cm are prepared by drawing contacts by monolithic cretacolor 8B pencil. X-ray diffractometer confirmed the deposition of nanocrystalline PbS films with 14 nm crystallites. The SEM illustrated the uniform coating of nanocrystalline PbS thin films on cellulose fibres of papers having an average thickness of fibres are 10 µm. The linear J-V characteristics in dark and under illumination of light using graphite trace on nanocrystalline PbS-on-paper shows good ohmic contact. The resistivity of pencil trace is 30 Ω.cm. Spectral response measurements of photodetector reveal the excellent sensitivity from 400 to 700 nm with a peak at 550 nm. The best responsivity anddetectivity are 0.7 A/W and 1.4 × 1012 Jones respectively. These paper-based low-cost photodetectors devices have fast photoresponse and recovery without baseline deviation.

Nanotextured thin films for detection of chemicals by surface enhanced Raman scattering

NASA Astrophysics Data System (ADS)

Korivi, Naga; Jiang, Li; Ahmed, Syed; Nujhat, Nabila; Idrees, Mohanad; Rangari, Vijaya

2017-11-01

We report on the development of large area, nanostructured films that function as substrates for surface enhanced Raman scattering (SERS) detection of chemicals. The films are made of polyethylene terephthalate layers partially embedded with multi-walled carbon nanotubes and coated with a thin layer of gold. The films are fabricated by a facile method involving spin-coating, acid dip, and magnetron sputtering. The films perform effectively as SERS substrates when used in the detection of dye pollutants such as Congo red dye, with an enhancement factor of 1.1  ×  106 and a detection limit of 10-7 M which is the lowest reported for CR detection by freestanding SERS film substrates. The films have a long shelf life, and cost US0.20 per cm2 of active area, far less than commercially available SERS substrates. This is the first such work on the use of a polymer layer modified with carbon nanotubes to create a nano-scale texture and arbitrary ‘hot-spots’, contributing to the SERS effect.

Electrical and optical properties of sol-gel derived La modified PbTiO 3 thin films

NASA Astrophysics Data System (ADS)

Chopra, Sonalee; Sharma, Seema; Goel, T. C.; Mendiratta, R. G.

2004-09-01

Lanthanum modified lead titanate (Pb 1- xLa xTi 1- x/4 O 3) PLT x ( x=0.08 i.e. PLT8) sol-gel derived thin films have been prepared on indium tin oxide (ITO) coated glass and quartz substrates using lead acetate trihydrate, lanthanum acetate hydrate and titanium isopropoxide as precursors along with 2-methoxyethanol as solvent and acetic acid as catalyst by spin coating method. The microstructure and surface morphology of the films annealed at 650 °C have been studied by X-ray diffraction technique and atomic force microscope (AFM). XRD has shown a single phase with tetragonal structure and AFM images have confirmed a smooth and crack-free surface with low surface roughness. The dependence of leakage current on applied voltage show ohmic behavior at low field region with a space charge conduction mechanism at high fields. The wavelength dispersion curve of thin films obtained from the transmission spectrum of thin films show that the films have high optical transparency in the visible region.

Efficient semitransparent perovskite solar cells for 23.0%-efficiency perovskite/silicon four-terminal tandem cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Bo; Bai, Yang; Yu, Zhengshan

Here, we have investigated semi-transparent perovskite solar cells and infrared enhanced silicon heterojunction cells for high-efficiency tandem devices. A semi-transparent metal electrode with good electrical conductivity and optical transparency has been fabricated by thermal evaporation of 7 nm of Au onto a 1-nm-thick Cu seed layer. For this electrode to reach its full potential, MAPbI3 thin films were formed by a modified one-step spin-coating method, resulting in a smooth layer that allowed the subsequent metal thin film to remain continuous. The fabricated semi-transparent perovskite solar cells demonstrated 16.5% efficiency under one-sun illumination, and were coupled with infrared-enhanced silicon heterojunction cellsmore » tuned specifically for perovskite/Si tandem devices. A double-layer antireflection coating at the front side and MgF2 reflector at rear side of the silicon heterojunction cells reduced parasitic absorption of near-infrared light, leading to 6.5% efficiency after filtering with a perovskite device and 23.0% summed efficiency for the perovskite/Si tandem device.« less

Characteristics of dye Rhoeo spathacea in dye sensitizer solar cell (DSSC)

NASA Astrophysics Data System (ADS)

Sumardiasih, Sri; Obina, Wilfrida M.; Cari; Supriyanto, Agus; Septiawan, Trio Y.; Khairuddin

2017-01-01

Dye-sensitized solar cell (DSSC) is a device that converts solar energy into electrical energy. The magnitude of the efficiency of DSSC is mainly based on the amount of dye absorbed by the surface of TiO2. In this work, used natural dye extracted from leaves Rhoeo spathacea. The dye partially used to immerse of TiO2 as working electrodes, and the rest are directly mixed TiO2 paste to obtain dye titanium dioxide.The paste TiO2 and dye titanium dioxide coated onto the fluorine-doped tin oxide (FTO) glass plate by spin coating method. The absorbance spectra of the dye, dye titanium dioxide and TiO2 were obtained by UV-Vis spectroscopy. The conductivity of the dye, dye titanium dioxide, and TiO2 was measured by two point probe El-Kahfi 100. The DSSC based on dye titanium dioxide that stirring for 5 hours the highest efficiency of 0,0520 % whereas those based on TiO2 immersed for 36 hours showed achieved 0,0501 % obtained from I-V characterization.

Vertically-tapered optical waveguide and optical spot transformer formed therefrom

DOEpatents

Bakke, Thor; Sullivan, Charles T.

2004-07-27

An optical waveguide is disclosed in which a section of the waveguide core is vertically tapered during formation by spin coating by controlling the width of an underlying mesa structure. The optical waveguide can be formed from spin-coatable materials such as polymers, sol-gels and spin-on glasses. The vertically-tapered waveguide section can be used to provide a vertical expansion of an optical mode of light within the optical waveguide. A laterally-tapered section can be added adjacent to the vertically-tapered section to provide for a lateral expansion of the optical mode, thereby forming an optical spot-size transformer for efficient coupling of light between the optical waveguide and a single-mode optical fiber. Such a spot-size transformer can also be added to a III-V semiconductor device by post processing.

Applications of remanent supermirror polarizers

NASA Astrophysics Data System (ADS)

Böni, P.; Clemens, D.; Kumar, M. Senthil; Pappas, C.

1999-06-01

Recent developments in sputtering techniques allow the fabrication of multilayers with a high degree of perfection over large areas. We show, that using reactive sputtering, it is possible to adjust the index of refraction for neutrons, ni, of the individual layers. This property is particularly important for polarizing mirrors, where nnm for the non-magnetic layers can be matched to nm of the magnetic layers such that neutrons for one spin-eigenstate are not reflected by the coating, whereas the reflectivity is high for the other spin-eigenstate. In addition, by using anisotropic sputtering conditions it is possible to orient the easy axis of magnetization within the plane of the mirrors in any particular direction resulting in a simultaneous appearance of a pronounced remanence and coercivity. Remanent polarizers can be used as broad band spin selectors at continuous and in particular at pulsed neutron sources thus eliminating the need of spin flippers, whose performance depends on the wavelength of the neutrons and is often strongly influenced by stray magnetic fields from the sample environment. The possibility to operate remanent supermirrors in arbitrary small fields leads to attractive applications of polarizing devices in low field environments such as they occur in neutron-spin-echo or in spin selective neutron guides. We present applications, where several tasks like polarizing, focusing and spin selection are performed in one single device thus reducing the problem of phase space matching between different neutron optical components.

Fabrication of Semi-quasi Solid DSSC using Spiro Material as Hole Transport Material

NASA Astrophysics Data System (ADS)

Safriani, L.; Primawati, W. P.; Mulyana, C.; Susilawati, T.; Aprilia, A.

2017-05-01

Dye Sensitized Solar Cells (DSSC) has been emerging a promising development in recent years. DSSC is a low-cost solar cell belonging to the third generation of solar cells. However, the conversion efficiency of DSSC is still far behind compared to silicon based solar cells. To produce long stability of DSSC, the used of solid state electrolyte is recommended instead of liquid electrolyte, though solid state DSSC also has problem relating to a lack of pore-filling hole transport material into mesoporous TiO2. In this work an attempt to improve performance of DSSC has been done by adding hole transport material into mesoporous TiO2 layer and optimizing fabrication method. In the first part of the work, we used low Tg material spiro-TAD and spiro-TPD as hole transport material with mosalyte and hybrid polymer as gel electrolyte to obtain a semi-quasi solid DSSC. In the second part, we modified fabrication method by annealing process before spin-coated spiro material into dye-coated TiO2 substrate. Current-voltage measurement of semi-quasi solid DSSC was performed using halogen lamp. We found that the used of spiro-TPD as hole transport give the best power conversion efficiency η = 2.03% of semi-quasi solid DSSC.

Effect of reduction time on third order optical nonlinearity of reduced graphene oxide

NASA Astrophysics Data System (ADS)

Sreeja, V. G.; Vinitha, G.; Reshmi, R.; Anila, E. I.; Jayaraj, M. K.

2017-04-01

We report the influence of reduction time on structural, linear and nonlinear optical properties of reduced graphene oxide (rGO) thin films synthesized by spin coating method. We observed that the structural, linear and nonlinear optical properties can be tuned with reduction time in GO is due to the increased structural ordering because of the restoration of sp2 carbon atoms with the time of reduction. The nonlinear absorption studies by open aperture Z-scan technique exhibited a saturable absorption. The nonlinear refraction studies showed the self de focusing nature of rGO by closed aperture Z scan technique. The nonlinear absorption coefficient and saturation intensity varies with the time for reduction of GO which is attributed to the depletion of valence band and the conduction band filling effect. Our results emphasize duration for reduction of GO dependent optical nonlinearity of rGO thin films to a great extent and explore its applications Q switched mode locking laser systems for generating ultra short laser pulses and in optical sensors. The rGO coated films were characterized by X-Ray diffraction method (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-Vis absorption spectroscopy (UV-Vis), Photoluminescence (PL) and Scanning electron microscope (SEM) measurements.

Scaled up Fabrication of High-Throughout SWNT Nanoelectronics and Nanosensor Devices

DTIC Science & Technology

2007-04-20

copolymer, polystyrene-block-ferrocenylethylmethylsilane (PS-b- PFEMS ) as the polymer-based catalyst for optimized SWNT growth. Spin coating a dilute...solution of 1 wt % PS-b- PFEMS in toluene provides uniform ~ 100nm thick films of the catalyst. In order to get well-separated individual SWNT or SWNT rope

Gas Sensor Test Chip

NASA Technical Reports Server (NTRS)

Buehler, M.; Ryan, M.

1995-01-01

A new test chip is being developed to characterize conducting polymers used in gas sensors. The chip, a seven-layer cofired alumina substrate with gold electrodes, contains 11 comb and U- bend test structures. These structures are designed to measure the sheet resistance, conduction anisotropy, and peripheral conduction of spin-coated films that are not subsequently patterned.

Influence of Ga doping ratio on the saturable absorption mechanism in Ga doped ZnO thin solid films processed by sol-gel spin coating technique

NASA Astrophysics Data System (ADS)

Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.; Byrappa, K.

2017-03-01

In the present study, the nonlinear optical properties of sol-gel spin coated gallium doped zinc oxide (GZO) thin solid films are explored with nanosecond laser pulses using the z-scan technique. The higher doping ratios of Ga result in a large redshift of the energy gap (0.38 eV) due to the existence of enhanced grain boundary defects in GZO films. A positive nonlinear absorption coefficient is observed in undoped 1 at.wt.% GZO and 2 at.wt.% GZO films, and a negative nonlinear absorption coefficient in 3 at.wt.% GZO film. Fewer defects in undoped 1% GZO and 2% GZO films resulted in reverse saturable absorption (RSA), whereas a saturable absorption (SA) mechanism is observed in 3% GZO films and is attributed to the enhanced defect concentration in the band structure of GZO. However, all the films showed a self-defocusing mechanism, derived by a closed aperture z-scan technique. The present work sheds light on the defect mechanism involved in the observed nonlinear properties of GZO films.

Simple color tuning of phosphorescent dendrimer light emitting diodes

NASA Astrophysics Data System (ADS)

Namdas, Ebinazar B.; Anthopoulos, Thomas D.; Samuel, Ifor D. W.; Frampton, Michael J.; Lo, Shih-Chun; Burn, Paul L.

2005-04-01

A simple way of tuning the emission color in solution processed phosphorescent organic light emitting diodes is demonstrated. For each color a single emissive spin-coated layer consisting of a blend of three materials, a fac-tris(2-phenylpyridyl)iridium (III) cored dendrimer (Ir-G1) as the green emitter, a heteroleptic [bis(2-phenylpyridyl)-2-(2'-benzo[4,5-α]thienyl)pyridyl]iridium (III) cored dendrimer [Ir(ppy)2btp] as the red emitter, and 4,4'-bis(N-carbazolyl) biphenyl (CBP) as the host was employed. By adjusting the relative amount of green and red dendrimers in the blends, the color of the light emission was tuned from green to red. High efficiency two layer devices were achieved by evaporating a layer of electron transporting 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene (TPBI) on top of the spin-coated emissive layer. A brightness of 100cd/m2 was achieved at drive voltages in the range 5.3-7.3 V. The peak external efficiencies at this brightness ranged from 31cd/A(18lm/W) to 7cd/A(4lm/W).

Ferromagnetism in spin-coated cobalt-doped TiO2 thin films and the role of crystalline phases

NASA Astrophysics Data System (ADS)

Salazar Cuaila, J. L.; Alayo, W.; Avellaneda, César O.

2017-11-01

Two sets of Cobalt-doped (1-10% at) TiO2 thin films, for different molar concentrations of the Ti precursor (0.3 and 0.5 mol/L), have been deposited onto Si substrates by combining the Sol Gel process and the Spin Coating technique. The structure of the samples was studied by X-ray reflectivity (XRR) and X-ray diffraction (XRD) and their magnetic properties were analyzed by magnetization measurements as a function of the applied magnetic field. The XRR results provided the thickness and interfacial roughness of the films, while XRD patterns revealed the crystalline phases and lattice parameters. Room temperature ferromagnetic behaviour was observed for some of the atomic Co concentrations by the magnetization measurements. This behaviour has been correlated to the crystalline phases, which were found to be modified by both the molar ratio of Ti precursor and the concentration of the Co dopant. A suppression of ferromagnetism is observed for some atomic Co fractions and it was attributed to the presence of secondary crystalline phases.

Impact on electronic structure of donor/acceptor blend in organic photovoltaics by decontamination of molybdenum-oxide surface

NASA Astrophysics Data System (ADS)

Ito, Yuta; Akaike, Kouki; Fukuda, Takeshi; Sato, Daisuke; Fuse, Takuya; Iwahashi, Takashi; Ouchi, Yukio; Kanai, Kaname

2018-05-01

Molybdenum oxide (MoOx) is widely used as the hole-transport layer in bulk-heterojunction organic photovoltaics (BHJ-OPVs). During the fabrication of solution-processed BHJ-OPVs on vacuum-deposited MoOx film, the film must be exposed to N2 atmosphere in a glove box, where the donor/acceptor blends are spin-coated from a mixed solution. Employing photoelectron spectroscopy, we reveal that the exposure of the MoOx film to such atmosphere contaminates the MoOx surface. Annealing the contaminated MoOx film at 160 °C for 5 min, prior to spin-coating the blend film, can partially remove the carbon and oxygen adsorbed on the MoOx surface during the exposure of MoOx. However, the contamination layer on the MoOx surface does not affect the energy-level alignment at the interface between MoOx and the donor/acceptor blend. Hence, significant improvement in the performance of BHJ-OPVs by mildly annealing the MoOx layer, which was previously reported, can be explained by the reduction of undesired contamination.

Effects of acid catalyst type on structural, morphological, and optoelectrical properties of spin-coated TiO2 thin film

NASA Astrophysics Data System (ADS)

Golobostanfard, Mohammad Reza; Abdizadeh, Hossein

2013-03-01

The effects of different acid catalysts of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, acetic acid, and citric acid on structural, morphological, and optoelectrical properties of nanocrystalline spin-coated TiO2 thin films synthesized via alkoxide sol-gel route were investigated. It was found that only the sols with HNO3 and HCl are suitable for film preparation. The X-ray diffractometry and Raman analysis showed that crystalline phases could be controlled by the type of acid catalyst. Although the H2SO4 sol shows good stability, it causes extremely different morphology to form due to its different sol nature and high contact angle. Fourier transformed infrared spectra confirmed the presence of acid anion species in all samples even after calcination. Furthermore, it was inferred from UV-visable absorption spectra that although the band gap and thickness of the films are independent of acid catalyst type, the refractive index and porosity of the films are strongly affected by the type of acids.

Spin-coated thin films of different metal phthalocyanines and porphyrin-phthalocyanine blend for optochemical sensors of volatile organic compounds

NASA Astrophysics Data System (ADS)

Rella, Roberto; Capone, Simona; Siciliano, Pietro; Spadavecchia, J.; Ciccarella, G.

2004-06-01

Spin-coated layers of ZnPc and CuP have been used as chemically interacting materials for the detection of alcohols, amines, ketones, alkanes and pyridine for applications in food quality control. The UV-VIS variations obtained by the exposure of the sensing layers to the mentioned analytes in controlled atmosphere have been analyzed and compared with those deriving by a single thin film obtained by mixing the two metal complexes in an appropriate ratio. A multichannel monitoring of the main bands of the sensing layer due to the interaction with the analyte vapors became the basis to construct a set of independent sensors located on a single sensing element. The effects in the variation of the absorption bands of the blend system are compared with the variations in absorbance observed with the two sensing layers fabricated separately with each single compound. The interaction between the VOCs species and the heterogeneous sensing layer shows a different behavior in the responses respect to the results obtained with each single compound.

Fabrication of ZnO and doped ZnO waveguides deposited by Spin Coating

NASA Astrophysics Data System (ADS)

Mohan, Rosmin Elsa; R, Neha P.; T, Shalu; C, Darshana K.; Sreelatha, K. S.

2015-02-01

In this paper, the synthesis of ZnO and doped Zn1-xAgxO (where x=0.03) nanoparticles by co- precipitation is reported. The precursors used were Zinc Nitrate and Potassium hydroxide pellets. For doping, 3% AgNO3 in ZnNO3 was considered as a separate buffer solution. The prepared nanoparticles were subsequently spin coated onto silica glass substrates at a constant chuck rate of 3000 rpm. The substrate acts as the lower cladding of a waveguide structure. The upper cladding is assumed to be air in the present investigation. The nanostructures of the ZnO powders in the doped and undoped cases were studied using X-ray Diffraction patterns. There was a decrease in the grain size with doping which increase the tunability of the powders to be used as photoluminescent devices. The optical characteristics of the sample were also investigated using UV-Visible spectrophotometer at 200-900 nm wavelengths. The photoluminescence peaks also report a dramatic increase in intensity at the same wavelength for the doped case compared to the undoped one.

X-ray photoelectron spectroscopy characterization of composite TiO 2-poly(vinylidenefluoride) films synthesised for applications in pesticide photocatalytic degradation

NASA Astrophysics Data System (ADS)

Losito, I.; Amorisco, A.; Palmisano, F.; Zambonin, P. G.

2005-02-01

X-ray photoelectron spectroscopy (XPS) was adopted for the analytical characterization of composite titanium dioxide-poly(vinylidenefluoride) (TiO 2-PVDF) films developed for applications in the photocatalytic degradation of pollutants. The composites were deposited on glass substrates by casting or spin coating from TiO 2-PVDF suspensions in dimethylformamide (DMF). XPS data on the TiO 2-PVDF surface composition were used to optimize preparation conditions (composition of the TiO 2/PVDF suspension, deposition technique) in terms of titanium dioxide surface amount and film stability. The use of spin-coating deposition and the increase of TiO 2 amount in the DMF suspensions were found to improve the titanium surface content, although high TiO 2/PVDF ratios led to film instability. PVDF-TiO 2 films were also used in preliminary photocatalytic degradation tests on isoproturon, a phenylurea herbicide, under solar UV irradiation; the results were compared to direct photolysis to evaluate the catalytic efficiency of immobilized TiO 2 and the role played by the PVDF film during the degradation process.

Laser-induced periodic surface structures nanofabricated on poly(trimethylene terephthalate) spin-coated films.

PubMed

Martín-Fabiani, I; Rebollar, E; Pérez, S; Rueda, D R; García-Gutiérrez, M C; Szymczyk, A; Roslaniec, Z; Castillejo, M; Ezquerra, T A

2012-05-22

Here we present a precise morphological description of laser-induced periodic surface structures (LIPSS) nanofabricated on spin-coated poly(trimethylene terephthalate) (PTT) films by irradiation with 266 nm, 6 ns laser pulses and by using a broad range of fluences and number of pulses. By accomplishing real and reciprocal space measurements by means of atomic force microscopy and grazing incidence wide- and small-angle X-ray scattering respectively on LIPSS samples, the range of optimum structural order has been established. For a given fluence, an increase in the number of pulses tends to improve LIPSS in PTT. However, as the pulse doses increase above a certain limit, a distortion of the structures is observed and a droplet-like morphology appears. It is proposed that this effect could be related to a plausible decrease of the molecular weight of PTT due to laser-induced chain photo-oxidation by irradiation with a high number of pulses. A concurrent decrease in viscosity enables destabilization of LIPSS by the formation of droplets in a process similar to surface-limited dewetting.

Developing upconversion nanoparticle-based smart substrates for remote temperature sensing

NASA Astrophysics Data System (ADS)

Coker, Zachary; Marble, Kassie; Alkahtani, Masfer; Hemmer, Philip; Yakovlev, Vladislav V.

2018-02-01

Recent developments in understanding of nanomaterial behaviors and synthesis have led to their application across a wide range of commercial and scientific applications. Recent investigations span from applications in nanomedicine and the development of novel drug delivery systems to nanoelectronics and biosensors. In this study, we propose the application of a newly engineered temperature sensitive water-based bio-compatible core/shell up-conversion nanoparticle (UCNP) in the development of a smart substrate for remote temperature sensing. We developed this smart substrate by dispersing functionalized nanoparticles into a polymer solution and then spin-coating the solution onto one side of a microscope slide to form a thin film substrate layer of evenly dispersed nanoparticles. By using spin-coating to deposit the particle solution we both create a uniform surface for the substrate while simultaneously avoid undesired particle agglomeration. Through this investigation, we have determined the sensitivity and capabilities of this smart substrate and conclude that further development can lead to a greater range of applications for this type smart substrate and use in remote temperature sensing in conjunction with other microscopy and spectroscopy investigations.

Performance and durability tests of smart icephobic coatings to reduce ice adhesion

NASA Astrophysics Data System (ADS)

Janjua, Zaid A.; Turnbull, Barbara; Choy, Kwang-Leong; Pandis, Christos; Liu, Junpeng; Hou, Xianghui; Choi, Kwing-So

2017-06-01

The accretion of ice can cause damage in applications ranging from power lines and shipping decks, to wind turbines and rail infrastructure. In particular on aircraft, it can change aerodynamic characteristics, greatly affecting the flight safety. Commercial aircraft are therefore required to be equipped with de-icing devices, such as heating mats over the wings. The application of icephobic coatings near the leading edge of a wing can in theory reduce the high power requirements of heating mats, which melt ice that forms there. Such coatings are effective in preventing the accretion of runback ice, formed from airborne supercooled droplets, or the water that the heating mats generate as it is sheared back over the wing's upper surface. However, the durability and the practicality of applying them over a large wing surface have been prohibitive factors in deploying this technology so far. Here, we evaluated the ice adhesion strength of four non-conductive coatings and seven thermally conductive coatings by shearing ice samples from coated plates by spinning them in a centrifuge device. The durability of the coating performance was also assessed by repeating the tests, each time regrowing ice samples on the previously-used coatings. Contact angle parameters of each coating were tested for each test to determine influence on ice adhesion strength. The results indicate that contact angle hysteresis is a crucial parameter in determining icephobicity of a coating and hydrophobicity is not necessarily linked to icephobicity.

Novel sol-gel precursors for thin mesoporous eu(3+)-doped silica coatings as efficient luminescent materials.

PubMed

Feinle, Andrea; Lavoie-Cardinal, Flavie; Akbarzadeh, Johanna; Peterlik, Herwig; Adlung, Matthias; Wickleder, Claudia; Hüsing, Nicola

2012-10-09

Europium(III) ions containing mesoporous silica coatings have been prepared via a solvent evaporation-induced self-assembly (EISA) approach of different single-source precursors (SSPs) in the presence of Pluronic P123 as a structure-directing agent, using the spin-coating process. A deliberate tailoring of the chemical composition of the porous coatings with various Si:Eu ratios was achieved by processing mixtures of tetraethylorthosilicate (TEOS) and Eu(3+)-coordinated SSPs. Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) analyses demonstrate that the thin metal oxide-doped silica coatings consist of a porous network with a short-range order of the pore structure, even at high europium(III) loadings. Furthermore, luminescence properties were investigated at different temperatures and different degrees of Eu(3+) contents. The photoluminescence spectra clearly show characteristic emission peaks corresponding to the (5)D0 → (7)FJ (J = 0-5) transitions resulting in a red luminescence visible by the eyes, although the films have a very low thickness (150-200 nm).

Manganite perovskite ceramics, their precursors and methods for forming

DOEpatents

Payne, David Alan; Clothier, Brent Allen

2015-03-10

Disclosed are a variety of ceramics having the formula Ln.sub.1-xM.sub.xMnO.sub.3, where 0.Itoreq.x.Itoreq.1 and where Ln is La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu or Y; M is Ca, Sr, Ba, Cd, or Pb; manganite precursors for preparing the ceramics; a method for preparing the precursors; and a method for transforming the precursors into uniform, defect-free ceramics having magnetoresistance properties. The manganite precursors contain a sol and are derived from the metal alkoxides: Ln(OR).sub.3, M(OR).sub.2 and Mn(OR).sub.2, where R is C.sub.2 to C.sub.6 alkyl or C.sub.3 to C.sub.9 alkoxyalkyl, or C.sub.6 to C.sub.9 aryl. The preferred ceramics are films prepared by a spin coating method and are particularly suited for incorporation into a device such as an integrated circuit device.

Calculation method of spin accumulations and spin signals in nanostructures using spin resistors

NASA Astrophysics Data System (ADS)

Torres, Williams Savero; Marty, Alain; Laczkowski, Piotr; Jamet, Matthieu; Vila, Laurent; Attané, Jean-Philippe

2018-02-01

Determination of spin accumulations and spin currents is essential for a deep understanding of spin transport in nanostructures and further optimization of spintronic devices. So far, they are easily obtained using different approaches in nanostructures composed of few elements; however their calculation becomes complicated as the number of elements increases. Here, we propose a 1-D spin resistor approach to calculate analytically spin accumulations, spin currents and magneto-resistances in heterostructures. Our method, particularly applied to multi-terminal metallic nanostructures, provides a fast and systematic mean to determine such spin properties in structures where conventional methods remain complex.

Biocorrosion behavior of biodegradable nanocomposite fibers coated layer-by-layer on AM50 magnesium implant.

PubMed

Abdal-Hay, Abdalla; Hasan, Anwarul; Kim, Yu-Kyoung; Yu-Kyoung; Lee, Min-Ho; Hamdy, Abdel Salam; Khalil, Khalil Abdelrazek

2016-01-01

This article demonstrates the use of hybrid nanofibers to improve the biodegradation rate and biocompatibility of AM50 magnesium alloy. Biodegradable hybrid membrane fiber layers containing nano-hydroxyapatite (nHA) particles and poly(lactide)(PLA) nanofibers were coated layer-by-layer (LbL) on AM50 coupons using a facile single-step air jet spinning (AJS) approach. The corrosion performance of coated and uncoated coupon samples was investigated by means of electrochemical measurements. The results showed that the AJS 3D membrane fiber layers, particularly the hybrid membrane layers containing a small amount of nHA (3 wt.%), induce a higher biocorrosion resistance and effectively decrease the initial degradation rate compared with the neat AM50 coupon samples. The adhesion strength improved highly due to the presence of nHA particles in the AJS layer. Furthermore, the long biodegradation rates of AM50 alloy in Hank's balanced salt solution (HBSS) were significantly controlled by the AJS-coatings. The results showed a higher cytocompatibility for AJS-coatings compared to that for neat Mg alloys. The nanostructured nHA embedded hybrid PLA nanofiber coating can therefore be a suitable coating material for Mg alloy as a potential material for biodegradable metallic orthopedic implants. Copyright © 2015 Elsevier B.V. All rights reserved.

A superconducting gyroscope to test Einstein's general theory of relativity

NASA Technical Reports Server (NTRS)

Everitt, C. W. F.

1978-01-01

Schiff (1960) proposed a new test of general relativity based on measuring the precessions of the spin axes of gyroscopes in earth orbit. Since 1963 a Stanford research team has been developing an experiment to measure the two effects calculated by Schiff. The gyroscope consists of a uniform sphere of fused quartz 38 mm in diameter, coated with superconductor, electrically suspended and spinning at about 170 Hz in vacuum. The paper describes the proposed flight apparatus and the current state of development of the gyroscope, including techniques for manufacturing and measuring the gyro rotor and housing, generating ultralow magnetic fields, and mechanizing the readout.

Research progress of nano self - cleaning anti-fouling coatings

NASA Astrophysics Data System (ADS)

Liu, Y.; Zhao, Y. J.; Teng, J. L.; Wang, J. H.; Wu, L. S.; Zheng, Y. L.

2018-01-01

There are many methods of evaluating the performance of nano self-cleaning anti-fouling coatings, such as carbon blacking method, coating reflection coefficient method, glass microbead method, film method, contact angle and rolling angle method, organic degradation method, and the application of performance evaluation method in self-cleaning antifouling coating. For the more, the types of nano self-cleaning anti-fouling coatings based on aqueous media was described, such as photocatalytic self-cleaning coatings, silicone coatings, organic fluorine coatings, fluorosilicone coatings, fluorocarbon coatings, polysilazane self-cleaning coatings. The research and application of different kinds of nano self-cleaning antifouling coatings are anlysised, and the latest research results are summed.

Dynamin recruitment and membrane scission at the neck of a clathrin-coated pit.

PubMed

Cocucci, Emanuele; Gaudin, Raphaël; Kirchhausen, Tom

2014-11-05

Dynamin, the GTPase required for clathrin-mediated endocytosis, is recruited to clathrin-coated pits in two sequential phases. The first is associated with coated pit maturation; the second, with fission of the membrane neck of a coated pit. Using gene-edited cells that express dynamin2-EGFP instead of dynamin2 and live-cell TIRF imaging with single-molecule EGFP sensitivity and high temporal resolution, we detected the arrival of dynamin at coated pits and defined dynamin dimers as the preferred assembly unit. We also used live-cell spinning-disk confocal microscopy calibrated by single-molecule EGFP detection to determine the number of dynamins recruited to the coated pits. A large fraction of budding coated pits recruit between 26 and 40 dynamins (between 1 and 1.5 helical turns of a dynamin collar) during the recruitment phase associated with neck fission; 26 are enough for coated vesicle release in cells partially depleted of dynamin by RNA interference. We discuss how these results restrict models for the mechanism of dynamin-mediated membrane scission. © 2014 Cocucci et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Rapid enzyme regeneration results in the striking catalytic longevity of an engineered, single species, biocatalytic biofilm.

PubMed

Tong, Xiaoxue; Barberi, Tania Triscari; Botting, Catherine H; Sharma, Sunil V; Simmons, Mark J H; Overton, Tim W; Goss, Rebecca J M

2016-10-21

Engineering of single-species biofilms for enzymatic generation of fine chemicals is attractive. We have recently demonstrated the utility of an engineered Escherichia coli biofilm as a platform for synthesis of 5-halotryptophan. E. coli PHL644, expressing a recombinant tryptophan synthase, was employed to generate a biofilm. Its rapid deposition, and instigation of biofilm formation, was enforced by employing a spin-down method. The biofilm presents a large three-dimensional surface area, excellent for biocatalysis. The catalytic longevity of the engineered biofilm is striking, and we had postulated that this was likely to largely result from protection conferred to recombinant enzymes by biofilm's extracellular matrix. SILAC (stable isotopic labelled amino acids in cell cultures), and in particular dynamic SILAC, in which pulses of different isotopically labelled amino acids are administered to cells over a time course, has been used to follow the fate of proteins. To explore within our spin coated biofilm, whether the recombinant enzyme's longevity might be in part due to its regeneration, we introduced pulses of isotopically labelled lysine and phenylalanine into medium overlaying the biofilm and followed their incorporation over the course of biofilm development. Through SILAC analysis, we reveal that constant and complete regeneration of recombinant enzymes occurs within spin coated biofilms. The striking catalytic longevity within the biofilm results from more than just simple protection of active enzyme by the biofilm and its associated extracellular matrix. The replenishment of recombinant enzyme is likely to contribute significantly to the catalytic longevity observed for the engineered biofilm system. Here we provide the first evidence of a recombinant enzyme's regeneration in an engineered biofilm. The recombinant enzyme was constantly replenished over time as evidenced by dynamic SILAC, which suggests that the engineered E. coli biofilms are highly metabolically active, having a not inconsiderable energetic demand. The constant renewal of recombinant enzyme highlights the attractive possibility of utilising this biofilm system as a dynamic platform into which enzymes of interest can be introduced in a "plug-and-play" fashion and potentially be controlled through promoter switching for production of a series of desired fine chemicals.

Self-Positioned Nanosized Mask for Transparent and Flexible Ferroelectric Polymer Nanodiodes Array.

PubMed

Hyun, Seung; Kwon, Owoong; Choi, Chungryong; Vincent Joseph, Kanniyambatti L; Kim, Yunseok; Kim, Jin Kon

2016-10-12

High density arrays of ferroelectric polymer nanodiodes have gained strong attention for next-generation transparent and flexible nonvolatile resistive memory. Here, we introduce a facile and innovative method to fabricate ferroelectric polymer nanodiode array on an ITO-coated poly(ethylene terephthalate) (PET) substrate by using block copolymer self-assembly and oxygen plasma etching. First, polystyrene-block-poly(2-vinylpyridine) copolymer (PS-b-P2VP) micelles were spin-coated on poly(vinylidene fluoride-ran-trifluoroethylene) copolymer (P(VDF-TrFE)) film/ITO-coated PET substrate. After the sample was immersed in a gold precursor (HAuCl 4 ) containing solution, which strongly coordinates with nitrogen group in P2VP, oxygen plasma etching was performed. During the plasma etching, coordinated gold precursors became gold nanoparticles (GNPs), which successfully acted as self-positioned etching mask to fabricate a high density array of P(VDF-TrFE)) nanoislands with GNP at the top. Each nanoisland shows clearly individual diode property, as confirmed by current-voltage (I-V) curve. Furthermore, due to the transparent and flexible nature of P(VDF-TrFE)) nanoisland as well as the substrate, the P(VDF-TrFE) nanodiode array was highly tranparent, and the diode property was maintained even after a large number of bendings (for instance, 1000 times). The array could be used as the next-generation tranparent and flexible nonvolatile memory device.

The effect of TiO2 thin film thickness on self-cleaning glass properties

NASA Astrophysics Data System (ADS)

Mufti, Nandang; Laila, Ifa K. R.; Hartatiek; Fuad, Abdulloh

2017-05-01

TiO2 is one of semiconductor materials which are widely used as photocatalyst in the form of a thin film. The TiO2 thin film is prepared by using the spin coating sol-gel method. The researcher prepared TiO2 thin film with 3 coating variations and X-Ray Diffraction characterization, UV-Vis Spectrophotometer, Electron Microscopy Scanning, and examined its hydrophilic and anti-fogging properties. The result of X-Ray Diffraction showed that the phase formed is the anatase on 101crystal field. The Electron Microscopy Scanning images showed that TiO2 thin films had a homogeneous surface with the particle sizes as big as 235 nm, 179 nm, and 137 nm. The thickness of each thin film was 2.06μm, 3.33μm, and 5.20μm. The characterization of UV-Vis Spectrophotometer showed that the greatest absorption to the wavelength of visible light was in the thin film’s thickness of 3 coatings with the band-gap determined by using 3.30 eV, 3.33 eV, and 3.33 eV Plot Tuoc. These results indicated that the rate of absorption would be increased by increasing the thickness of film. The increasing thickness of the thin film makes the film hydrophilic able to be used as an anti-fogging substance.

Influence of HF acid catalyst concentration on properties of aerogel low-k thin films

NASA Astrophysics Data System (ADS)

Gaikwad, A. S.; Gupta, S. A.; Mahajan, A. M.

2016-08-01

The effect of hydrofluoric acid (HF) catalyst concentration in coating solution on chemical, physical and structural properties of silica aerogel thin films was investigated. The aerogel films were synthesized by using a sol-gel spin coating method followed by aging in ethanol and CO2 supercritical drying. The refractive index (RI) is observed to be reduced from 1.32 to 1.13 and porosity percentage increased from 30.21% to 71.64% in accordance with increasing HF concentration. Deposition of silica aerogel was confirmed from Fourier transform infrared spectroscopy measurement. The nanoporous nature of deposited films was confirmed from field effect scanning electron microscopy and observed pore diameter is in the range of 3.33 to 6.69 nm. The nanoporous nature of the film was also validated from atomic force microscopy and root mean square roughness was observed to be increased from 2.31 nm to 3.2 nm with increasing acid catalyst concentration in the coating solution. The calculated dielectric constant from CV measurement of fabricated metal-insulator-semiconductor structure for the silica aerogel formed at 0.8 ml HF concentration is observed to be 1.73. These deposited nanoporous silica aerogel low-k films with lower k value and smaller pore size have application as interlayer dielectric materials to minimize the disadvantages of porous materials.

Characterization of polymer, DNA-based, and silk thin film resistivities and of DNA-based films prepared for enhanced electrical conductivity

NASA Astrophysics Data System (ADS)

Yaney, Perry P.; Ouchen, Fahima; Grote, James G.

2009-08-01

DC resistivity studies were carried out on biopolymer films of DNA-CTMA and silk fibroin, and on selected traditional polymer films, including PMMA and APC. Films of DNA-CTMA versus molecular weight and with conductive dopants PCBM, BAYTRON P and ammonium tetrachloroplatinate are reported. The films were spin coated on glass slides configured for measurements of volume dc resistance. The measurements used the alternating polarity method to record the applied voltage-dependent current independent of charging and background currents. The Arrhenius equation plus a constant was fitted to the conductivity versus temperature data of the polymers and the non-doped DNA-based biopolymers with activation energies ranging from 0.8 to 1.4 eV.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sankar, M. S. Ravi, E-mail: rameshg.phy@pondiuni.edu; Gangineni, Ramesh Babu, E-mail: rameshg.phy@pondiuni.edu

The present work reveals soft lithography strategy based on self assembly and replica molding for carrying out micro and nanofabrication. It provides a convenient, effective and very low cost method for the formation and manufacturing of micro and nano structures. Al-layer of compact disc (sony CD-R) used as a stamp with patterned relief structures to generate patterns and structures with pattern size of 100nm height, 1.7 μm wide. In literature, PDMS (Polydimethylsiloxane) solution is widely used to get negative copy of the Al-layer. In this work, we have used inexpensive white glue (Polyvinylacetate + water), 15gm (□5) and PVDF (Polyvinylidenemore » difluoride) spin coated films and successfully transferred the nano patterns of Al layer on to white glue and PVDF films.« less

Synthesis, characterization, and photocatalytic properties of nanocrystalline NZO thin films

NASA Astrophysics Data System (ADS)

Aryanto, D.; Hastuti, E.; Husniya, N.; Sudiro, T.; Nuryadin, B. W.

2018-03-01

Nanocrystalline Ni-doped ZnO (NZO) thin films were synthesized on glass substrate using sol-gel spin coating methods. The effect of annealing on the structural and optical properties of nanocrystalline thin film was studied using X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), UV-VIS spectrophotometry, and photoluminescence (PL). The results showed that the annealing temperature strongly influenced the physical properties of nanocrystalline NZO thin films. The photocatalytic properties of nanocrystalline NZO thin films were evaluated using an aqueous solution of Rhodamine-B. The photocatalytic activity of nanocrystalline NZO thin films increased with the increase of annealing temperature. The results indicated that the structure, morphology, and band gap energy of nanocrystalline NZO thin films played an important role in photocatalytic activity.

Indium tin oxide films prepared by atmospheric plasma annealing and their semiconductor-metal conductivity transition around room temperature

NASA Astrophysics Data System (ADS)

Li, Yali; Li, Chunyang; He, Deyan; Li, Junshuai

2009-05-01

We report the synthesis of indium tin oxide (ITO) films using the atmospheric plasma annealing (APA) technique combined with the spin-coating method. The ITO film with a low resistivity of ~4.6 × 10-4 Ω cm and a high visible light transmittance, above 85%, was achieved. Hall measurement indicates that compared with the optimized ITO films deposited by magnetron sputtering, the above-mentioned ITO film has a higher carrier concentration of ~1.21 × 1021 cm-3 and a lower mobility of ~11.4 cm2 V-1 s-1. More interestingly, these electrical characteristics result in the semiconductor-metal conductivity transition around room temperature for the ITO films prepared by APA.

Effect of solution concentration on MEH-PPV thin films

NASA Astrophysics Data System (ADS)

Affendi, I. H. H.; Sarah, M. S. P.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

MEH-PPV thin films were prepared with a mixture of THF (tetrahydrofuran) solution deposited by spin coating method. The surface topology of MEH-PPV thin film were characterize by atomic force microscopy (AFM) and optical properties of absorption spectra were characterized by using Ultraviolet-visible-near-infrared (UV-Vis-NIR). The MEH-PPV concentration variation affects the surface and optical properties of the thin film where 0.5 mg/ml MEH-PPV concentration have a good surface topology provided the same film also gives the highest absorption coefficient were then deposited to a TiO2 thin film forming composite layer. The composite layer then shows low current flow of short circuit current of Isc = -5.313E-7 A.

Structural and magnetic analysis of Cu, Co substituted NiFe{sub 2}O{sub 4} thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Hakikat; Bala, Kanchan; Negi, N. S.

2016-05-23

In the present work we prepared NiFe{sub 2}O{sub 4}, Ni{sub 0.95}Cu{sub 0.05}Fe{sub 2}O{sub 4} and Ni{sub 0.94}Cu{sub 0.05}Co{sub 0.01} Fe{sub 2}O{sub 4} thin films by metallo-organic decomposition method (MOD) using spin coating technique. The thin films were analyzed by X-ray diffractometer (XRD) and Atomic force microscope (AFM) for structural studies. The XRD patterns confirmed the ferrite phase of thin films. From AFM, we analyzed surface morphology, calculated grain size (GS) and root mean square roughness (RMSR). Room temperature magnetic properties were investigated by vibrating sample magnetometer (VSM).

Triblock copolymer micelles as templates for preparation of mesoporous niobia thin films

NASA Astrophysics Data System (ADS)

Georgiev, R.; Christova, D.; Todorova, L.; Georgieva, B.; Vasileva, M.; Novakov, Ch; Babeva, T.

2018-03-01

The micelle formation of commercially available Pluronic PE 6800 (PEO-PPO-PEO triblock copolymer) was studied by means of a dye solubilization method, and the solubility of 1,6-diphenyl-1,3,5-hexatriene in aqueous solutions of the copolymer with concentrations ranging from 0.05 to 20 % w/v was studied by recording the transmission and emission spectra of the solutions using UV-VIS and photoluminescence spectroscopy, respectively. Further, mesoporous Nb2O5 films using PE 6800 micelles templates were obtained through sol-gel using spin-coating; their morphology, structure and optical properties were studied by TEM, SAED and nonlinear fitting of reflectance measurements. The possible application of the films in optical sensing of vapors was demonstrated and discussed.

Nanofabrication on unconventional substrates using transferred hard masks

DOE PAGES

Li, Luozhou; Bayn, Igal; Lu, Ming; ...

2015-01-15

Here, a major challenge in nanofabrication is to pattern unconventional substrates that cannot be processed for a variety of reasons, such as incompatibility with spin coating, electron beam lithography, optical lithography, or wet chemical steps. Here, we present a versatile nanofabrication method based on re-usable silicon membrane hard masks, patterned using standard lithography and mature silicon processing technology. These masks, transferred precisely onto targeted regions, can be in the millimetre scale. They allow for fabrication on a wide range of substrates, including rough, soft, and non-conductive materials, enabling feature linewidths down to 10 nm. Plasma etching, lift-off, and ion implantationmore » are realized without the need for scanning electron/ion beam processing, UV exposure, or wet etching on target substrates.« less

Immobilization of bacterial S-layer proteins from Caulobacter crescentus on iron oxide-based nanocomposite: synthesis and spectroscopic characterization of zincite-coated Fe₂O₃ nanoparticles.

PubMed

Habibi, Neda

2014-05-05

Zinc oxide was coated on Fe2O3 nanoparticles using sol-gel spin-coating. Caulobacter crescentus have a crystalline surface layer (S-layer), which consist of one protein or glycoprotein species. The immobilization of bacterial S-layers obtained from C. crescentus on zincite-coated nanoparticles of iron oxide was investigated. The SDS PAGE results of S-layers isolated from C. crescentus showed the weight of 50 KDa. Nanoparticles of the Fe2O3 and zinc oxide were synthesized by a sol-gel technique. Fe2O3 nanoparticles with an average size of 50 nm were successfully prepared by the proper deposition of zinc oxide onto iron oxide nanoparticles surface annealed at 450 °C. The samples were characterized by field-emission scanning electron microscope (FESEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). Copyright © 2014 Elsevier B.V. All rights reserved.

Fabrication of efficient graphene-doped polymer/fullerene bilayer organic solar cells in air using spin coating followed by ultrasonic vibration post treatment

NASA Astrophysics Data System (ADS)

Zabihi, Fatemeh; Chen, Qianli; Xie, Yu; Eslamian, Morteza

2016-12-01

In this work, in an attempt to improve the performance and lifetime of organic solar cells, P3HT photon absorbing polymer was doped with graphene (G) nano-sheets, to make light harvesting G-P3HT composite thin film. The composite this film was then employed as the donor of a bilayer organic solar cell with the structure of glass/ITO/PEDOT:PSS/G-P3HT/C60/Al. The reference P3HT:PCBM bulk heterojunction solar cell was also fabricated for comparison. All solution-processed layers were made by spin coating in humid air (Shanghai, China); C60 and Al were deposited by thermal evaporation. An effective mechanical treatment approach developed by the authors, i.e. the application of forced ultrasonic vibration on the wet spun-on films, was used to improve the dispersion of graphene in G-P3HT composite films to obtain a uniform nanostructure. This mechanical method eliminates tedious and expensive chemical steps, currently performed to engineer the structure of organic solar cells. It is evidenced that the G-P3HT composite thin films, post treated by ultrasonic vibration at the optimum vibration duration, possess superior electrical conductivity, charge carrier mobility and density, uniform surface potential distribution, and lower surface roughness, compared to those of P3HT and G-P3HT thin films made without vibration. The results show significant improvement in the power conversion efficiency (PCE) of vibration-treated G-P3HT/C60 cell (PCE = 5.17%, the highest reported for this structure), substantiating the strong positive effect of using graphene and forced vibration for the fabrication of P3HT active layer in the bilayer cell structure.

Photochemical conversion of tin-oxo cage compounds studied using hard x-ray photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Zhang, Yu; Haitjema, Jarich; Liu, Xiaomeng; Johansson, Fredrik; Lindblad, Andreas; Castellanos, Sonia; Ottosson, Niklas; Brouwer, Albert M.

2017-03-01

Several metal-containing molecular inorganic materials are currently considered as photoresists for extreme ultraviolet lithography (EUVL). This is primarily due to their high EUV absorption cross section and small building block size, properties which potentially allow both high sensitivity and resolution as well as low line-edge roughness. The photochemical reaction mechanisms that allow these kinds of materials to function as photoresists, however, are still poorly understood. As a step in this direction, we here discuss photochemical reactions upon deep UV (DUV) irradiation of a model negative-tone EUV photoresist material, namely the well-defined molecular tin-oxo cage compound [(SnR)12O14(OH)6]X2 (R = organic group; X = anion) which is spin coated to thin layers of 20 nm. The core electronic structure (Sn 3d, O 1s and C 1s) of fresh and DUV exposed films were then investigated using synchrotron radiationbased hard X-ray photoelectron spectroscopy (HAXPES). This method provides information about the structure and chemical state of the respective atoms in the material. We performed a comparative HAXPES study of the composition of the tin-oxo cage compound [(SnR)12O14(OH)6](OH)2, either fresh directly after spin-coated vs. DUV-exposed materials under either ambient condition or under a dry N2 atmosphere. Different chemical oxidation states and concentrations of atoms and atom types in the fresh and exposed films were found. We further found that the chemistry resulting from exposure in air and N2 is strikingly different, clearly illustrating the influence of film-gas interactions on the (photo)chemical processes that eventually determine the photoresist. Finally, a mechanistic hypothesis for the basic DUV photoreactions in molecular tin-oxo cages is proposed.

Integrated optical-fiber capillary electrophoresis microchips with novel spin-on-glass surface modification.

PubMed

Lin, Che-Hsin; Lee, Gwo-Bin; Fu, Lung-Ming; Chen, Shu-Hui

2004-07-30

This paper presents a novel micro-capillary electrophoresis (CE) chip with embedded optical fibers for the on-line detection of DNA samples. The optical fibers are pre-etched and then inserted directly into fiber channels incorporated within low-cost soda-lime glass substrates. The embedded optical fibers are precisely aligned with the microfluidic channels such that the induced fluorescence signals from labeled bio-samples can be detected. This arrangement avoids the requirement for delicate optical alignment procedures and equipment. Surface modification of the CE channels is accomplished by means of a simple and reliable organic-based spin-on-glass (SOG) method. The zeta potential distribution and the corresponding electroosmotic mobility of the fluid are simulated numerically for the modified and non-modified channel surfaces, and then both sets of results are verified experimentally. The present results indicate that the value of the zeta potential for a surface with an SOG coating is 19.3 times smaller than that of an untreated surface. A phiX-174 DNA marker fluid is used to evaluate the injection and separation performance of the developed micro-CE device. Furthermore, the long-term stability of the SOG-coated surface is also investigated. The experimental data reveal that the microchip device is capable of providing highly efficient separations of bio-molecules, and that the SOG layer retains its low zeta potential characteristics for at least 45 days. The present results confirm the effectiveness of the proposed micro-CE chip in performing the on-line detection of DNA samples, and indicate that the SOG process represents a simple and reliable solution for the surface modification of glass-based microchannels.

Influence of an Interfacial Effect on the Laser Performance of a Rhodamine 6G/Cellulose Acetate Waveguide on a Vinylidene Fluoride Copolymer Layer.

PubMed

Tsutsumi, Naoto; Hirano, Yoshinori; Kinashi, Kenji; Sakai, Wataru

2018-06-12

The fluorescent properties of dyes and fluorophores in condensed matter significantly affect the laser performance of organic dye lasers and fluorescent polymer lasers. Concentration quenching of fluorescence is commonly observed in condensed matter. Several approaches have been presented to suppress such quenching, such as the use of a dendrimer and the use of effective energy transfer in a guest-host system. The enhanced fluorescence of rhodamine 6G (R6G) dye on a vinylidene fluoride polymer is an alternative method for enhancing laser performance because of the roughness of the P(VDF-TrFE) surface and the interaction between polar β-crystals of P(VDF-TrFE) and R6G dye. In this paper, a significant improvement in slope efficiency (SE) is demonstrated without a significant depression in the lasing threshold for distributed feedback (DFB) and distributed Bragg reflector (DBR) lasers fabricated using an R6G-dispersed cellulose acetate (CA) matrix spin-coated onto a copolymer of vinylidene fluoride and trifluoroethylene P(VDF-TrFE) thin film. SEs of 3.4 and 1.3% were measured for DBR and DFB laser devices with CA/R6G on a P(VDF-TrFE) thin film, respectively, whereas an SE of less than 1.0% was measured for both corresponding laser devices without a P(VDF-TrFE) thin film. From the aspect of simple fabrication procedures, repeatability in device fabrication and performance, stability of the device, time for device fabrication, the present approach is the most preferable way for industrial applications, requiring only the additional step of spin-coating of a P(VDF-TrFE) thin film.

Fabrication and characterization of shape memory polymers at small-scales

NASA Astrophysics Data System (ADS)

Wornyo, Edem

The objective of this research is to thoroughly investigate the shape memory effect in polymers, characterize, and optimize these polymers for applications in information storage systems. Previous research effort in this field concentrated on shape memory metals for biomedical applications such as stents. Minimal work has been done on shape memory polymers; and the available work on shape memory polymers has not characterized the behaviors of this category of polymers fully. Copolymer shape memory materials based on diethylene glycol dimethacrylate (DEGDMA) crosslinker, and tert butyl acrylate (tBA) monomer are designed. The design encompasses a careful control of the backbone chemistry of the materials. Characterization methods such as dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC); and novel nanoscale techniques such as atomic force microscopy (AFM), and nanoindentation are applied to this system of materials. Designed experiments are conducted on the materials to optimize spin coating conditions for thin films. Furthermore, the recovery, a key for the use of these polymeric materials for information storage, is examined in detail with respect to temperature. In sum, the overarching objectives of the proposed research are to: (i) Design shape memory polymers based on polyethylene glycol dimethacrylate (PEGDMA) and diethylene glycol dimethacrylate (DEGDMA) crosslinkers, 2-hydroxyethyl methacrylate (HEMA) and tert-butyl acrylate monomer (tBA). (ii) Utilize dynamic mechanical analysis (DMA) to comprehend the thermomechanical properties of shape memory polymers based on DEGDMA and tBA. (iii) Utilize nanoindentation and atomic force microscopy (AFM) to understand the nanoscale behavior of these SMPs, and explore the strain storage and recovery of the polymers from a deformed state. (iv) Study spin coating conditions on thin film quality with designed experiments. (iv) Apply neural networks and genetic algorithms to optimize these systems.

Relaxation rates of low-field gas-phase ^129Xe storage cells

NASA Astrophysics Data System (ADS)

Limes, Mark; Saam, Brian

2010-10-01

A study of longitudinal nuclear relaxation rates T1 of ^129Xe and Xe-N2 mixtures in a magnetic field of 3.8 mT is presented. In this regime, intrinsic spin relaxation is dominated by the intramolecular spin-rotation interaction due to persistent xenon dimers, a mechanism that can be quelled by introducing large amounts of N2 into the storage cell. Extrinsic spin relaxation is dominated by the wall-relaxation rate, which is the primary quantity of interest for the various low-field storage cells and coatings that we have tested. Previous group work has shown that extremely long gas-phase relaxation times T1 can be obtained, but only at large magnetic fields and low xenon densities. The current work is motivated by the practical benefits of retaining hyperpolarized ^129Xe for extended periods of time in a small magnetic field.

High-Resolution Spin-on-Patterning of Perovskite Thin Films for a Multiplexed Image Sensor Array.

PubMed

Lee, Woongchan; Lee, Jongha; Yun, Huiwon; Kim, Joonsoo; Park, Jinhong; Choi, Changsoon; Kim, Dong Chan; Seo, Hyunseon; Lee, Hakyong; Yu, Ji Woong; Lee, Won Bo; Kim, Dae-Hyeong

2017-10-01

Inorganic-organic hybrid perovskite thin films have attracted significant attention as an alternative to silicon in photon-absorbing devices mainly because of their superb optoelectronic properties. However, high-definition patterning of perovskite thin films, which is important for fabrication of the image sensor array, is hardly accomplished owing to their extreme instability in general photolithographic solvents. Here, a novel patterning process for perovskite thin films is described: the high-resolution spin-on-patterning (SoP) process. This fast and facile process is compatible with a variety of spin-coated perovskite materials and perovskite deposition techniques. The SoP process is successfully applied to develop a high-performance, ultrathin, and deformable perovskite-on-silicon multiplexed image sensor array, paving the road toward next-generation image sensor arrays. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Luminescence quenching of tris(2,2'-bipyridine)ruthenium(II) by 2,6-dimethylphenol and 4-bromo-2,6-dimethylphenol in sol-gel-processed silicate thin films.

PubMed

Altamirano, M; Senz, A; Gsponer, H E

2004-02-15

The luminescence properties of tris(1,2-bipyridine)ruthenium(II) (Ru(bpy)(3)(2+)), included in different organically modified silicate gel matrixes were investigated. Spin and dip-coated thin films were prepared from methyltrimethoxysilane (MTMOS) and methyltriethoxysilane (MTEOS). A blue shift in the emission spectrum of the MLCT excited state of Ru(bpy)(3)(2+) with respect to the aqueous solution was observed in all the films, practically independent of the reaction pH used to prepare the "sol," silane-derived precursor, and procedure used (dip-coating or spin-coating) to obtain the film. A bimodal distribution of probe sites in the films was obtained from modeling of the emission decays by a double exponential and from application of the exponential series method. The parameters of the decay components depended principally on the thermal treatment used in the processing of the films. The lifetimes decreased with the increase in the drying temperature of the films; at the same time, the emission spectra showed a red shift and the luminescence efficiency decreased. A luminescence quenching of the ruthenium complex in the films by 4-bromo-2,6-dimethylphenol and 2,6-dimethylphenol in aerated aqueous solution at pH 12 in contact with the film was also observed. The quenching plots obtained from luminescence intensities or luminescence intensity decay measurements showed a downward curvature. These plots could be fitted satisfactorily by a sum of two Stern-Volmer terms with quenching constants K(SV1) and K(SV2) associated with two different binding sites of the ruthenium complex. This result is indicative of the matrix microheterogeneity in the films and is fully consistent with the biexponential nature of the luminescence intensity decay profiles. The Stern-Volmer parameter values for both sites in the films suggest that only a low percentage of the probe is accessible to the quencher and its respective constant K(SV1) is lower than in water.

SiC/GaN Based Optically Triggered MESFET for High Power Efficiency and High Radiation Resistance Solid State Switch Application for Actuator System

DTIC Science & Technology

2016-06-23

somnath.chattopadhyay@csun.edu 1-818-677-7197 clean/etch. Excessively hard- baked photoresist can usually be dissolved in piranha etching solution. 48 hours of...coated onto the freshly cleaned and dried wafer at 3000RPM, then soft- baked at 180ºC for 120 seconds. This gives a PMGI layer of about 0.4µm. Then the...PR is spin coated onto the wafer at about 4000RPM and soft baked at 115ºC for 90seconds, resulting in a PR layer about 1.3µm thick. The wafer is

Formation of thin film like assembly of exfoliated C3N4 nanoflakes by solvent non-evaporative method using centrifuge

NASA Astrophysics Data System (ADS)

Tejasvi, Ravi; Basu, Suddhasatwa

2017-12-01

A simple method for depositing a thin film of nanomaterial on a substrate using centrifugation technique has been developed, whereby solvent evaporation is prevented and solvent reuse is possible. The centrifuge technique of deposition yields uniform, smooth thin film irrespective of substrate surface texture. The deposited TiO2/eC3N4 film studied, through field emission scanning electron microscope, atomic force microscope, and optical surface profilometer, shows variation in surface roughness on the basis of centrifugation speeds. Initially film coverage improves and surface roughness decreases with the increase in rpm of the centrifuge and the surface roughness slightly increases with further increase in rpm. The photoelectrochemical studies of TiO2/eC3N4 films suggest that the centrifuge technique forms better heterojunctions compared to that by spin coating technique leading to enhanced photoelectrochemical water splitting.

Modulating light propagation in ZnO-Cu₂O-inverse opal solar cells for enhanced photocurrents.

PubMed

Yantara, Natalia; Pham, Thi Thu Trang; Boix, Pablo P; Mathews, Nripan

2015-09-07

The advantages of employing an interconnected periodic ZnO morphology, i.e. an inverse opal structure, in electrodeposited ZnO/Cu2O devices are presented. The solar cells are fabricated using low cost solution based methods such as spin coating and electrodeposition. The impact of inverse opal geometry, mainly the diameter and thickness, is scrutinized. By employing 3 layers of an inverse opal structure with a 300 nm pore diameter, higher short circuit photocurrents (∼84% improvement) are observed; however the open circuit voltages decrease with increasing interfacial area. Optical simulation using a finite difference time domain method shows that the inverse opal structure modulates light propagation within the devices such that more photons are absorbed close to the ZnO/Cu2O junction. This increases the collection probability resulting in improved short circuit currents.