CdS thin film: Synthesis and characterization

CdS thin films have been deposited by dip technique using succinic acid as a complexing agent. The structural characterizations of films have been studied by X-ray diffraction. X-ray diffraction pattern prove crystallinity of the deposited films that crystallize in the cubic phase of CdS. The films show high absorption and band gap value which were found to be 2.58 eV. The specific conductivity of the film was found to be in the order of 10^?7 (Ω cm)^?1.     

Photosensitization of TiO2 nanoparticulate thin film electrodes by CdS nanoparticles

Surface photovoltage spectra (SPS) measurements of TiO₂ show that a large surface state density is present on the TiO₂ nanoparticles and these surface states can be efficiently decreased by sensitization using CdS nanoparticles as well as by suitable heat treatment. The photoelectrochemical behavior of the bare TiO₂ thin film indicates that the mechanism of photoelectron transport is controlled by the trapping/detrapping properties of surface states within the thin films. The slow photocurrent response upon the illumination can be explained by the trap saturation effect. For a TiO₂ nanoparticulate thin film sensitized using CdS nanoparticles, the slow photocurrent response disappears and the steady-state photocurrent increases drastically, which suggests that photosensitization can decrease the effect of surface states on photocurrent response. Electronic Publication     

Pattern formation in draining thin film suspensions

We demonstrate the emergence of complexity from remarkably simple and ubiquitous systems: draining thin-film suspensions exhibiting a striking transition between two classes of self-organizing patterns. Vertical channels form when attractive forces lead to transient gelation, while horizontal bands result from granular mixtures. We propose an explanation whereby the generic physical mechanisms require only the existence of viscous and excluded-volume couplings among the particles, solvent, and substrate. System-specific, small inhomogeneities trigger large-scale pattern formation, through collective dynamics, where jamming plays a crucial role. Our results shed light on emergent complexity in bio- and geophysical processes and have implications for coatings and food industries.     

多硫电解质对CdS薄膜电池光电性能影响研究

在CdS薄膜的光电化学电池中,多硫电解质起着促进电子传递,减少电子空穴复合几率,从而提高电池光电转换效率的作用;但多硫电解质又会阻碍CdS薄膜对光的吸收。本文通过对CdS纳米管薄膜电池在含硫量不同的电解质中光电性能的考察,证明了0.5 mol/L Na2S、0.5 mol/L NaOH和0.5 mol/L S的液态电解质成分组合为本实验中制得的CdS纳米管薄膜光电化学电池的最佳电解质。     

CdS薄膜及其光电化学电池阳离子识别特性的研究

半导体材料CdS薄膜具有优良的光电特性,一直受到人们的关注,广泛用于许多无机薄膜太阳电池的n型窗口层[1,2]。用CdS薄膜组装的光电化学电池也一度引起人们的极大兴趣。二十世纪七十年代以来,半导体光电化学在光能-电能转换、光能-化学能转换和太阳能的光电化学利用方面得到了蓬     

Organic thin film formation using asymmetric surface-active viologens

In the present study, asymmetric surface-active viologens were applied successfully for the thin film formation of organic pigments using the immersion plating technique. The influences of the hydrophobicity of the surfactants and the pH of the plating solution on the film formation were investigated. In addition, the interfacial chemistry and electrochemistry of the surfactants were studied, and the mechanism of the film formation has been proposed and discussed.     

Ethanol-assisted graphene oxide-based thin film formation at pentane-water interface

Graphene oxide (GO) can be viewed as an amphiphilic soft material, which form thin films at organic solvent-water interfaces. However, organic solvent evaporation provides little driving force, which results in slow GO transfer in aqueous phase, thus dawdling GO film formation processes for various potential applications. We present an ethanol-assisted self-assembly method for the quick formation of GO or GO-based composite thin films with tunable composition, transmittance, and surface resistivity at pentane-water interface. The thickness of pure GO and reduced GO (rGO) films ranging from ~1 nm to more than 10 nm can be controlled by the concentration of GO in bulk solution. The transmittance of rGO films can be tuned from 72% to 97% at 550 nm while the surface resistivity changes from 8.3 to 464.6 kΩ sq(-1). Ethanol is essential for achieving quick formation of GO thin films. When ethanol is injected into GO aqueous dispersion, it serves as a nonsolvent, compromising the stability of GO and providing driving force to allow GO sheets aggregate at the water-pentane interface. On the other hand, neither the evaporation of pentane nor the mixing between ethanol and water provides sufficient driving forces to allow noteworthy amount of GO sheets to migrate from the bulk aqueous phase to the interface. This method can also be extended to prepare GO-based composites thin films with tunable composition, such as GO/single walled carbon nanotube (SWCNT) composite thin films investigated in this work. Reduced GO/SWCNT composite films show much lower surface resistivity compared to pure rGO thin films. This ethanol-assisted self-assembly method opens opportunities to design and fabricate new functional GO-based hybrid materials for various potential applications.     

Comprehensive investigation of self-assembled monolayer formation on ferromagnetic thin film surfaces

We report a simple, universal method for forming high surface coverage SAMs on ferromagnetic thin (< or =100 nm) films of Ni, Co, and Fe. Unlike previous reports, our technique is broadly applicable to different types of SAMs and surface types. Our data constitutes the first comprehensive examination of SAM formation on three different ferromagnetic surface types using two different surface-binding chemistries (thiol and isocyanide) under three different preparation conditions: (1) SAM formation on electroreduced films using a newly developed electroreduction approach, (2) SAM formation on freshly evaporated surfaces in the glovebox, and (3) SAM formation on films exposed to atmospheric conditions beforehand. The extent of SAM formation for all three conditions was probed by cyclic voltammetry for surfaces functionalized with either (11-thiolundecyl)ferrocene (Fc-(CH2) 11-SH) or (11-isocyanoundecyl)ferrocene (Fc-(CH2) 11-NC). SAM formation was also probed for straight-chain molecules, hexadecanethiol and hexadecaneisocyanide, with contact angle measurements, X-ray photoelectron spectroscopy, and reflection-absorption infrared spectroscopy (RAIRS). The results show that high surface coverage SAMs with low surface-oxide content can be achieved for thin, evaporated Ni and Co films using our electroreduction process with thiols. The extent of SAM formation on electroreduced films is comparable to what has been observed for SAMs/Au and to what we observe for SAMs/Ni, Co, and Fe samples prepared in the glovebox.     

Wave formation by heating in thin metal film on an elastomer

Wave formation by heating rather than the usual cooling in a thin metal film on an elastomer is presented. A simple model is used to relate the wavelength of the waves thus formed to the heating temperature. An indirect method of estimating Young's modulus at elevated temperatures emerges from the analysis. The waves formed by heating can be made to appear or not to appear by the selection of the temperature to which the sample is heated. A relationship is given for the critical temperature that determines the appearance or nonappearance of the waves. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1122–1128, 2001     

Dynamics of terrace formation in a nanostructured thin block copolymer film

We have used dynamic self-consistent field (DSCF) theory to investigate the structural evolution of an ABA block copolymer thin film placed between a solid substrate and a free surface. In line with the few existing theoretical studies for pure homopolymers and mixtures, the free interface is introduced by a void component. In our calculations, the free surface experiences surface roughening and eventually the formation of terraces, as in the experiments. The kinetic pathway of the microstructures was compared to findings of an existing detailed experimental study (Knoll, A.; Lyakhova, K. S.; Horvat, A.; Krausch, G.; Sevink, G. J. A.; Zvelindovsky, A. V.; Magerle, R. Nat. Mater. 2004, 3, 886) and was found to be equivalent in detail. This corroborates our assumption in this earlier work that the pathway due to changing film thickness is similar to a pathway due to changing surface energetics. Moreover, our calculations show for the first time that microstructural transitions are a driving force of polymer/air interface curving and the formation of terraces.     

Ordered droplet formation by thin polymer film dewetting on a stripe-patterned substrate

The dewetting process of thin polystyrene (PS) film on flat and stripe-patterned substrates is presented. Different dewetting processes were observed when the thin PS films annealed at above the glass transition temperature on these different kinds of substrates. The final dewetting on the flat substrate led to formation of polygonal liquid droplets, while on the stripe-patterned substrate, the droplets were observed to align at the centers of the stripes. A possible explanation for the dewetting process on the stripe-patterned substrate is proposed.     

Laser-induced thin film formation from a gaseous mixture of trimethylsilylacetylene and methyl acrylate

Under irradiation with N₂ laser light, gaseous trimethylsilylacetylene (TMeSiA) and a gaseous mixture of TMeSiA and methyl acrylate (MA) produced thin films on an incident optical quartz window of an irradiation vessel. The product yield decreased with increasing partial pressure of TMeSiA. From the analysis of FT-IR spectra and X-ray photoelectron spectra of the deposited films, it was shown that Si---C bond of TMeSiA was cleaved by a two-photon absorption of N₂ laser light to produce trimethylsilyl radical and the silanes, R(CH₃)Si=CH₂ (R: H₃C---, CHC---). Trimethylsilyl radical reacted with MA at C=C and C=O bonds to produce Si---C and Si---O bonds in the film deposited from the gaseous mixture. The silanes were polymerized in each other to produce a thin film from pure TMeSiA vapor. Under irradiation with a medium pressure mercury lamp, a gaseous mixture of TMeSiA and MA produced aerosol particles in addition to the film. Polymeric species of TMeSiA was more involved in the aerosol particles rather than in the film, suggesting that collisionally induced chemical reaction takes place efficiently between excited MA and TMeSiA molecules.     

Conductive thin film formation onto radiation grafted polymeric surfaces using electroless plating technique

Surface modification of polypropylene films (PP) was carried out via radiation induced graft copolymerization of 4‐vinyl pyridine (4VP) and acrylamide (AAm) to enhance the adhesion ability of the PP surface for electroless deposition of copper. Factors affecting the grafting process such as suitable solvent, comonomer composition and concentration and irradiation dose were optimized. The grafted films produced were characterized by studying their Fourier‐transform infrared (FTIR) spectra and thermal stability. The grafted films were copper‐plated by electroless deposition using Pd as the catalyst to initiate the redox reaction. The influence of catalytic activation method parameters on the plating rate were studied. Scanning electron microscopy revealed a dense and void‐free copper deposited film. The adhesion of the deposited copper film to the modified PP films was determined by measuring the tensile strength of the copper plated films. The electrical characteristics of the copper plated films in comparison with grafted films were studied. The results showed the high adhesion of the deposited copper film to the grafted PP film as well as the high electrical conductivity. Copyright © 2008 John Wiley & Sons, Ltd.     

Photocatalytic formation of porous CdS/ZnO nanospheres and CdS nanotubes

It was found that ZnO nanocrystals have photocatalytic activity in the formation of CdS during the reduction of sulfur in the presence of cadmium acetate. It was shown that mesoporous spheres measuring 150–170 nm and consisting of CdS/ZnO particles measuring 5–8 nm are formed during the irradiation of ZnO particles measuring 5.5 nm. During the photodeposition of CdS by the action of light on nanorods produced by ultrasonic treatment of microcrystalline zinc oxide nanotubes of CdS 0.5–0.8 μm in length and 15–110 nm in internal diameter are formed. A mechanism, in which they appear at the ends of the ZnO nanorods and grow on the surface of the CdS/ZnO heterojunction, is proposed for the formation of the CdS nanotubes. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 4, pp. 215–219, July–August, 2007.     

Organic thin film pyrosensors

Recent developments in sensor technology show the suitability of thin pyroelectric films for the construction of pyroelectric sensor devices made from polymer materials. These materials are used for its advantageous thermal properties and also for its suitable frequency behaviour. Pyroelectrical measurements have been provided on thin films based upon poly(vinyl alcohol)s and poly(siloxane)s with azobenzene side chains. Relaxation behaviour and stability of poled pyroelectric polymers are discussed and related to the results of dipole relaxation measurements provided at our laboratories.     

The influence of DMSO on the formation and photoelectrochemical properties of CdS thin films by electrodeposition method

The homodispersed CdS nanoparticles were prepared on Sn-doped indium oxide substrates (ITO) to form smooth and uniform CdS thin films by electrodeposition method from a dimethyl sulfoxide (DMSO) solution containing cadmium chloride and sulfur. The structure and morphologies of samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. The results indicate that DMSO played an important role in formation of CdS nanofilms by affecting the nucleation and growth of the CdS nanoparticles. So, a DMSO-assisted growth process was proposed as a plausible mechanism for the formation of smooth and uniform CdS nanofilms. According to the photoelectrochemical test, the CdS thin film prepared in 30 % DMSO + 70 % H₂O system exhibited maximum photocurrent and open circuit potentials. This is because the deposited CdS nanoparticles had better dispersity on ITO, which facilitated the propagation and kinetic separation of photogenerated charges.     

Fe/Si multi-layer thin film anodes for lithium rechargeable thin film batteries

Fe/Si multi-layer thin films were prepared by alternate deposition using an electron-beam evaporation method. Electrochemical results through galvanostatic charge–discharge experiments are presented. It appears that the volumetric expansion of silicon during cycling can be effectively suppressed by forming a Fe layer between Si layers. The electrochemical characteristics of Fe/Si multi-layer film electrode can be controlled by the thickness, and number of stacked Si layers, and post-annealing.     

Molecular dynamics simulation of thin film formation by energetic cluster impact (ECI)

Langevin Molecular Dynamics Simulations have been performed in order to understand thin film formation by impact of energetic clusters. The impact of Mo₁₀₂₄ clusters on a Mo surface is simulated at kinetic energies between 1 and 10 eV per atom. The results are in qualitative agreement with the experiments. Due to the high temperature induced locally at the impact zone, the method can be used to form compact, smooth, and strongly adhering thin films on room temperature substrates.     

The role of scavengers in the CdS film corrosion

Journal of Solid State Electrochemistry - The cadmium sulfide (CdS) is one of the most applied chalcogenides to the water splitting (WS) on photoelectrochemical cells (PEC). The CdS bandgap is...