CuS Thin Films Research Articles

Enhanced tribological performance of CuS thin film on Si substrate: the case of APS-PAA buffer layer

Purpose – The purpose of this paper was to demonstrate the influence of a 3-aminopropyl-triethoxysilane–polyacrylic acid (amino propyl silane (APS)-PAA) buffer layer on the tribological performance of copper sulfide (CuS) thin film on silicon (Si) substrate. Design/methodology/approach – The APS-PAA buffer layer was first deposited on Si substrate by a self-assembling method. Then, the deposited film was coated by a CuS film by a successive ionic layer absorption and reaction (SILAR) method. The structures and morphologies of the prepared films were characterized by X-ray diffraction and atomic force microscopy. The results showed that the prepared CuS film with a PAA-APS double layer had a good crystallinity and surface morphology. The tribological performance of the prepared film was analyzed on UMT-2 tribometer and scanning electric microscope. Findings – With use of an APS-PAA buffer layer, the CuS thin films became compact, smooth and uniform. The tribological performance of the CuS film was greatly enhanced by using an APS-PAA buffer layer. Originality/value – The paper is the first to demonstrate that the CuS film exhibited enhanced structure, morphology and tribological characteristics by using an APS-PAA buffer layer.

Influence of Thickness on the Photosensing Properties of Chemically Synthesized Copper Sulfide Thin Films

We report here the influence of thickness on the photosensing properties of copper sulfide (CuS) thin films. The CuS films were deposited onto glass substrate by using a simple and cost effective chemical bath deposition method. The changes in film thickness as a function of time were monitored. The films were characterized using X-ray diffraction technique (XRD), field emission scanning electron microscopy (FE-SEM), optical measurement techniques and electrical measurement. X-ray diffraction results indicate that all the CuS thin films have an orthorhombic (covellite) structure with preferential orientation along (113) direction. The intensity of the diffraction peaks increases as thickness of the film increases. Uniform deposition having nanocrystalline granular morphology distributed over the entire glass substrate was observed through FE-SEM studies. The crystalline and surface properties of the CuS thin films improved with increase in the film thickness. Transmittance (except for 210 nm thick CuS film) together with band gap values was found to decrease with increase in thickness. I-V measurements under dark and illumination condition show that the CuS thin films give a good photoresponse.

Nanostructured Multilayer Composite Films of Manganese Dioxide/Nickel/Copper Sulfide Deposited on Polyethylene Terephthalate Supporting Substrate

Nanostructured multilayer manganese dioxide/nickel/copper sulfide (MnO2/Ni/CuS) composite films were successfully deposited onto supporting polyethylene terephthalate (PET) substrate through the sequential deposition of CuS, Ni, and MnO2 thin films by chemical bath deposition, electrodeposition, and horizontal submersion deposition techniques, respectively. Deposition of each thin‐film layer was optimized by varying deposition parameters and conditions associated with specific deposition technique. Both CuS and Ni thin films were optimized for their electrical conductivity whereas MnO2 thin film was optimized for its microstructure and charge capacity. The electrochemical properties of nanostructured multilayer MnO2/Ni/CuS composite films were evaluated by cyclic voltammetry as electrode materials of an electrochemical capacitor prototype in a dual‐planar device configuration. Cyclic voltammogram in mild Na2SO4 aqueous electrolyte exhibited a featureless and almost rectangular shape which was indicative of the ideal capacitive behavior and high cycling reversibility of the electrochemical capacitor prototype. Nanostructured multilayer MnO2/Ni/CuS composite films on supporting polyethylene terephthalate (PET) substrate could potentially be utilized as electrode materials for the fabrication of high performance electrochemical capacitors.

Growth of nanocrystalline CuS thin films at room temperature by a facile chemical deposition method

Good quality nanocrystalline CuS thin films in terms of structure, optical absorbance, and light emission were successfully deposited by a very facile chemical method at low temperature using tri-sodium citrate as a non-toxic complexing agent.

Facile chemical bath deposition of CuS nano peas like structure as a high efficient counter electrode for quantum-dot sensitized solar cells

In this paper, highly efficient nano peas like structure CuS film has been successfully employed in quantum dot sensitized solar cells (QDSSCs) for its highest catalytic activity at minimal cost. The CuS thin film electrode was deposited on fluorine-doped tin oxide (FTO) substrate by chemical bath deposition technique using urea at low deposition temperatures. This electrode elevated the short circuit current and fill factor in comparison to the frequently used Pt electrode. Moreover, electrochemical measurement data disclosed higher electrocatalytic activity toward polysulfide reduction. The CuS film exhibited an average particle size of 180–270nm and film thickness of 825nm. It also revealed superior Jsc (13.87mA/cm2) and conversion efficiency of 4.01% which is remarkably higher than that of the Pt-based cell (1.07%). In addition, stability test conducted for both CuS and Pt-based cells for about 900min at working conditions affirmed that the long-term stability of the CuS film decreased by 16.66% (4.02–3.35%), while that of the Pt based cell got elevated by 24.29% until 700min, and consequently diminished by 8.27% from 700 to 900min.

Influence of Cu vacancy on knit coir mat structured CuS as counter electrode for quantum dot sensitized solar cells.

Knit-coir-mat-like structured CuS thin films prepared by chemical bath deposition with different time duration were used as counter electrode in qunatum dot sensitized solar cells. The film deposited at 4 h exhibited better electrochemical and photovoltaic performance with JSC, VOC, and FF values of 14.584 mA cm(-2), 0.566 V, and 54.57% and efficiency of 4.53%. From the UV-vis absorption spectra, it is observed that CuS thin film exhibits free carrier intraband absorption in the longer wavelengh region. The enhanced performance of CuS counter electrodes is due to Cu vacancies with increased S composition, and the quasi-Fermi energy level in semiconductors with respect to electrolyte redox potential is one of the causes that affects the electrocatalytic activity of counter electrodes.

Conversion of CuS thin films to structured nanosheet CuyS (1 < y ≦ 2) by vacuum annealing

In this study, large‐area and uniform thickness novel nano‐sheet structured CuS thin films on ITO glass have been prepared by the one‐step electrodeposition method from a dimethyl sulfoxide solution. Thin films of completely preserved nano‐sheet like morphology of CuyS (y = 1.75, 1.8, 1.95, and 2.0) are grown by vacuum annealing CuS thin films at 500 °C for different lengths of time. The 500 °C sample heated for 10 hours was nearly converted to single phase of Cu2S with y ∼ 2. The optical direct band gaps of nano‐sheet CuyS thin films annealed at 500 °C of 2, 6, and 10 hours in vacuum were found to be 1.94, 1.68, and 1.44 eV, respectively.

CuS nano flakes and nano platelets as counter electrode for quantum dots sensitized solar cells

A facile chemical bath deposited (CBD) CuS nanoflakes and nano platelets are used as an effective counter electrode (CE) for quantum dot sensitized solar cells (QDSSC) and the effect of seed layer assistance has been discussed. The CuS thin films used as CE exhibit intraband transitions in the longer wavelength region with direct band gap and the surface exhibits unique morphology depending upon the seed layer. The photovoltaic performance of TiO2/CdS/CdSe/ZnS cascade QDSSC with CuS as CE prepared at 60°C shows increased electrocatalytic activity in polysulfide electrolyte with higher short- circuit current density, open circuit voltage, fill factor and a conversion efficiency of 4.02%.

Nanostructured Multilayer Manganese Dioxide/Nickel/Copper Sulfite (MnO2/Ni/CuS) Composite Films for Electrochemical Applications

Nanostructured multilayer manganese dioxide/nickel/copper sulfite (MnO2/Ni/CuS) composite films were successfully deposited on supporting polyethylene terephathalate (PET) substrate through the sequential deposition of CuS, Ni and MnO2 thin films by chemical bath deposition, electrodeposition, and horizontal submersion deposition techniques, respectively. Deposition of each thin-film layer was optimized through varying deposition parameters and conditions associated with specific deposition technique. Both CuS and Ni thin films were optimized for their electrical conductivity whereas MnO2 thin film was optimized for its microstructure and charge capacity. The electrochemical properties of nanostructured multilayer MnO2/Ni/CuS composite films were evaluated by cyclic voltammetry as electrode materials of electrochemical capacitor prototype in a dual planar device configuration. Cyclic voltammograms in mild Na2SO4 aqueous electrolyte exhibited a featureless and almost rectangular shape which was indicative of ideal capacitive behavior and high cycling reversibility for prolonged cycling up to 1,500 cycles. Nanostructured multilayer MnO2/Ni/CuS composite films on supporting polyethylene terephathalate (PET) substrate could potentially be utilized as electrode materials for the fabrication of high performance electrochemical capacitors.

Thickness dependences of the structural optical, and electrical properties of Cu2 Se thin films grown by using DC magnetron sputtering

The thickness dependences of the structural, optical, and electrical properties of p-type Cu2Se films have been investigated in the thickness range of 200–600 nm. X-ray diffraction analysis confirmed that a stoichiometric Cu2Se phase with a cubic structure was formed. From the Hall effect measurements, the electrical resistivity of the Cu2Se film showed a low resistivity of 4.21 × 10−5 Ω·cm. The optical band gap energy estimated from the optical transmittance measurements varied in the range from 2.01 to 2.41 eV at room temperature Moreover, the surface roughness of the film increased with increasing film thickness.

Optical and Structural Study of CuSe and CuSe/In Thin Films

The preparation of (Cu,Se)(In,N) thin films by r.f magnetron sputtering technique opens an interesting research area with potential application in solar cells. In this work, we presented a systematic study of growth and characterization of CuSe thin films and layers of CuSe/In deposited on glass substrates by varying the power r.f source and substrate temperature. The effects of experimental parameters on morphology and the optical properties of the films were investigated by XRD, UV-Visible and SEM. The results show that the samples are polycrystalline with a hexagonal structure for the CuSe films, and tetragonal structure for the CuSe/In layers. SEM images took on the surface of the films, showed a change in their morphology, evidencing a strong dependence of the experimental parameters. From UV-Visible measurements determine the bandgap and the optical behaviour of the films.

Structural and Electrical Properties of Copper Sulfide (CuS) Thin Films doped with Mercury and Nickel impurities

Chemical bath deposited copper sulfide (CuS) thin films were doped with varying concentrations of mercury (Hg) and nickel (Ni) impurities (0.01-0.03M) on glass substrates at room temperature of 27 o C. X-ray diffraction (XRD) and four-point probe techniques were used to analyze the structural and electrical properties as well as the thickness of the doped CuS thin films. The XRD results reveal that the films have mono-crystallite structure with broadening of the diffraction peak by both impurities. Values of the Bragg's angle obtained were 2ϴ = 29.28 o for the diffraction peak of Ni impurities and 2ϴ = 27.86 o for the diffraction peak of Hg impurities as compared to un-doped CuS thin films whose diffraction peak occurred at 2ϴ = 23.71 o . The electrical resistivity of the films dropped from about 2000 Ω-cm for the un-doped CuS thin film to zero value for 0.01M of Ni impurities and then reversed from negative value back to zero for Ni impurities of equal to or greater than 0.02M concentration. For Hg impurities, the electrical resistivity first rose to 6,600 Ω-cm for 0.01M impurity, then dropped symmetrically back to 2000 Ω-cm for 0.02M impurity and gradually decreased with higher concentrations of Hg impurities. Corresponding variations in electrical conductivity, dielectric constants and film thickness with impurity concentrations are also reported in this paper.

Effect of heat-treatment on the structural and optical properties of Cu2S thin films deposited by CBD method

Semiconducting Cu2S thin films were successfully deposited on glass substrate under three different conditions such as as-deposited, post heat-treated and pre heated precursor solution by chemical bath deposition technique. Structural and optical properties of the films were characterized by X-ray diffraction (XRD), scanning electron microscope, energy dispersive X-ray (EDX) analysis and UV–Visible spectrophotometer. The XRD spectra showed the amorphous nature of thin films with hexagonal structure. The d value and micro strain increased and the average crystallite size decreased from 1.9 to 1.4 and 1.3 nm respectively when the as-deposited film was subjected to post heat-treatment and the precursor solution temperature was elevated. The presence of more nucleation centers and fast reaction rate decreased the average crystallite size in films grown with pre heated precursor solution. The noticed blue shift in energy gap and the shift of XRD peak position towards the lower 2θ side by heat-treatment could be considered as a sign of the quantum confined effect due to the formation of the nano-sized Cu2S crystals on the surface. The transmittance of heat-treated Cu2S films in the visible region matched the phototropic vision of human eye (~600 nm) which makes them suitable for solar control coatings on architectural windows and automobiles in the regions with warm climates. Low transmittance behaviour of pre heated Cu2S films could be used for anti dazzling coatings for car windscreens and driving mirrors to reduce the dazzling effects of light at night. EDX spectra showed the chemical purity of the films. The observed broad absorption and blue shift in band gap of the heat-treated films were due to quantum confinement effect. Fourier transform infrared studies were also carried out and the results are presented.

Characterization of CuS nanocrystalline thin films synthesized by chemical bath deposition and dip coating techniques

CuS thin films were synthesized by chemical bath deposition and dip coating techniques at ambient temperature. The energy dispersive analysis of X-rays of the thin films confirmed that both the as synthesized thin films are stoichiometric. The X-ray diffraction of the chemical bath deposited and dip coating deposited thin films showed that the films possess hexagonal structure having lattice parameters, a=b=3.79Ǻ and c=16.34Ǻ. The crystallite sizes determined from the X-ray diffraction data using Scherrer's formula for the chemical bath deposition and dip coating deposition thin films came out to be nearly 11nm and 13nm, respectively. The optical microscopy of the as deposited thin films surfaces showed that the substrates are well covered in both the deposited films. The scanning electron microscopy of the thin films clearly showed that in chemical bath deposited thin films the grain size varies from few μm to nm, while in dip coating deposited films the grain size ranges in nm. The optical bandgap determined from the optical absorbance spectrum analysis showed, chemical bath deposited thin films possess direct bandgap of 2.2eV and indirect bandgap of 1.8eV. In the case of dip coating deposited thin films, the direct bandgap is 2.5eV and indirect bandgap is 1.9eV. The d.c. electrical resistivity variation with temperature for both the deposited films showed that the resistivity decreases with temperature thus confirming the semiconducting nature. The thermoelectric power variations with temperature and the room temperature Hall Effect study of both the synthesized CuS thin films showed them to be of p-type conductivity. The obtained results are discussed in details.

Preparation and Study the Structural and Optical Properties of CuS nano film

Thin films of CuS were prepared by Successive Ionic Layer And Reaction (SILAR) method from solution of CuCl2 and Na2S at two different molarities (0.03 M and 0.06 M) on glass substrates at room temperature. The structural and optical properties of CuS films were determined using X-ray diffraction (XRD) and UV-VIS spectrophotometer respectively. The films are polycrystalline, very adherent to the substrate and well crystallized according to the centered cubic structure with preferential orientation along (103) . It was found that the energy gap of CuS varies from 2.4eV to 2.8eV for thickness of 0.55µm and 0.82µm respectively (i.e depending on the deposition conditions).

Preparation and Characterization of Nanocrystalline CuS Thin Films for Dye-Sensitized Solar cells

A dye-sensitized nanocrystalline copper sulphide (CuS) solar cell is developed using crystal violet (CV) as a photosensitizer. Nanocrystalline CuS thin film is deposited on indium tin oxide- (ITO-) coated glass substrate by chemical bath deposition (CBD) technique. These thin films are characterized for their structural, optical and electrical properties using X-ray diffractometer (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Optical absorbance measurements from UV-visible spectrometer at normal incidence of light in the wavelength range of 320–1100 nm and current-voltage (I-V) measurements were also made. The deposited CuS thin film on ITO-coated glass substrate may be used as a photo electrode in the fabrication of dye-sensitized solar cell (DSSC). The carbon soot collected on the substrate is used as a counter electrode. The counter electrode coupled with a dye-sensitized CuS thin film along with a redox electrolyte mixture is used to develop a complete photovoltaic cell. The fill factor and efficiency were evaluated for the developed DSSC.

Structural, Morphological and Optical Properties of (Cu2S)100-x(SnS2)x Thin Films

The structural , optical and morphological properties of SnS2 , Cu2S thin films and their mixture prepared by spray pyrolysis technique , were studied. SnS2 , Cu2S thin films and their mixture were deposited on glass substrates at temperature of 334°C, 283°C and 300°C respectively. XRD studies showed that all the prepared films were polycrystalline in nature with a hexagonal structure and the preferential orientation for Cu2S thin film was along (002) plane , while the preferential orientation for SnS2 thin films was along (101) plane . The absorbance and transmittance spectra have been recorded in the wavelength (310-1100) nm in order to study the optical properties . It was found that the electronic transitions on fundamental absorption edge were direct allowed and the values of the optical energy gap for SnS2 andCu2S was equal to 2.2eV and 2.35eV respectively. Also it was found that the values of the optical energy gap for the mixture decreased with the increase in SnS2 in the mixture from (2.32-2.22) eV. The optical constants which include refractive index and extinction coefficient as a function of photon energy were also studied.

In situ fabricate Cu2S thin film with hierarchical petal-like nanostructures

In this paper, Cu2S thin film with hierarchical petal-like nanostructures has been successfully in situ synthesized via a solvothermal method using DMSO as reactant under appropriate reaction conditions. The crystalline phase, morphology and optical properties of the resulting products were characterized by X-ray diffraction, energy-dispersive X-ray spectrometry, scanning electron microscopy and UV–vis absorption spectroscopy, respectively. The band gap is estimated to be about 1.0eV by the results of UV–vis absorption spectroscopy of the Cu2S thin film with hierarchical nanostructures that consisted of nanoslices with the thickness of 15nm. The formation process of Cu2S and the possible mechanism of hierarchical nanostructures were also proposed. These findings are valuable since Cu2S thin film with hierarchical petal-like nanostructures are promising candidate as lithium ion battery and solar cell materials.

Morphological and optical characterization of thermally evaporated copper sulphide thin films

Thin films of Cu2S on opaque gold layers and quartz substrates at the temperature of 393 K were deposited by a thermal evaporation technique. The surface morphology of the Cu2S thin films at different thicknesses is investigated by AFM. It is seen that all the films are composed of highly coordinated spherical nano-sized particles well adhered to the substrate. The transmittance and reflectance spectra of Cu2S thin films on the quartz substrate were recorded by a UV–visible spectrophotometer. The results show that the thermally evaporated Cu2S thin films have the characteristic transmittance and reflectance suitable for optoelectronic applications. The stoichiometry and surface morphology of a grown Cu2S thin film were confirmed by energy-dispersive X-ray spectroscopy (EDAX) and scanning electron microscopy (SEM), respectively. The dependence of the refractive index and the extinction coefficient on the photon energy for both the surface film and the opaque gold layer have been determined by ellipsometry. From the spectral behaviour of the absorption coefficient at two distinct absorption regions, a dual-band scheme of optical absorption for a Cu2S thin film is described. The indirect and direct edges of Cu2S are found to be about at 0.91 eV and 2.68 eV, respectively.

SYNTHESIS OF COPPER SULPHIDE(CUS) THIN FILM BY CHEMICAL BATH DEPOSITION METHOD AND ITS CHARACTERIZATION

The CuS thin films were deposited on glass substrates using the chemical bath deposition technique at 65⁰C temperature from aqueous solutions of copper sulphate and thiourea in which tartaric acid solution were employed as the complexing agent. HRXRD studies reveal covellite CuS, having hexagonal primitive crystal structure. AFM studies shows morphology of CuS thin film as spherical particles, and spiky cones showing probability of nanorod formation of CuS. The grains are distributed homogeneously with a pattern consistent with polycrystalline film. Lower value of RMS value for CuS 8 sample of thin film (15.5907nm) shows that less light is scattered by an optical surface, and hence better the surface quality of thin film. Absorbance of thin film observed between 300-350 nm. The highest transmittance of the as-grown film in the entire wavelength of interest was recorded as 50%.