Dip-coating Deposition Technique Research Articles

Advancement of stannite Cu2CoSnS4 thin films deposited by sol gel dip-coating route

In this research effort, we synthesized copper-cobalt-tin-sulphur Cu2CoSnS4 (CCoTS) absorbers by sol–gel process associated with the dip-coating deposition technique on the ordinary glass substrates. We synthesized the impact of annealing temperature without utilization sulfurization on the structural, compositional, morphological, optical and electrical characteristics of layers annealed at 280 °C, 300 °C, 320 °C and 340 °C. CCoTS absorbers have been controlled by different control techniques included x-ray diffraction (XRD), Raman spectroscopic, Energy dispersive x-ray spectroscopy (EDS), Scanning electron microscopy (SEM), UV–vis spectroscopy and four-point probe technique (FPP). XRD patterns exhibited a polycrystalline structure with peaks agreeing to the (112), (204) and (312) directions and matching well with those of the pure stannite phase of CCoTS. The size of crystallites was found in the variety of 8.23–11.27 nm. Raman spectroscopic presented a peak at 332 cm−1 which is the signature of the pure stannite phase of CCoTS. EDS analysis measurements presented a close stoichiometric CCoTS thin films composition. SEM micrographs demonstrated an enhancement in films density and uniformity with annealing temperature rises. It was found that the band gap decreased from 1.72 to 1.5 eV with rising of annealing temperature. The sheet resistance was observed between 27.83 and 56.23 Ω sq−1. These properties are quite interesting and can make the dip-coater CCoTS films as suitable novel absorbers for photovoltaic devices.

Transparent boron-doped zinc oxide films for antibacterial and magnetic applications

B-doped ZnO thin films have been synthesized by a sol–gel dip-coating deposition technique. Deposition conditions were optimized to achieve highly ordered thin films. XRD patterns confirm that B ions are inserted into the ZnO; lattice and the crystallite size decrease from 25.83 to 20.94 nm as the amount of B increases to optimal value (9 at.wt%). Synthesized B-doped ZnO thin films have ordered hexagonal wurtzite structures and granular morphology with high specific surface area. Optical transmittance spectra display transparency in the visible region. The band gap of the films decreases from 3.89 to 3.04 eV with the increase in B concentration. Band gap lowering is due to increase of defect level with the increase in B dopant percentage. The origin of the ferromagnetism is explained in terms of oxygen vacancies and Zn interstitials. Dielectric constant increases while DC conductivity and AC conductivity decrease with the increase in B doping. Antibacterial activity increases with the increase in B doping percentage but lower than undoped ZnO due to large crystallite size of B-doped ZnO nanostructures.

Comparison between glass and glass-ceramic silica-hafnia matrices on the down-conversion efficiency of Tb3+/Yb3+ rare earth ions

In this paper, the investigation of energy transfer efficiency in Tb3+-Yb3+ co-doped SiO2-HfO2 glass and glass-ceramic waveguides is presented. Cooperative energy transfer between these two ions allows to cut one UV or 488 nm photon in two 980 nm photons and could have important applications in improving the performance of photovoltaic solar cells. Thin films with different molar concentrations of rare earths, up to a total concentration of 21%, were prepared by a sol-gel route, using dip-coating deposition technique on SiO2 substrates. The ratio between Yb3+ and Tb3+ ions in all the prepared thin films is constant and equal to 4. The energy transfer between Tb3+ and Yb3+ ions in glass and glass-ceramic waveguides shows the higher efficiency for glass-ceramic with a maximum quantum transfer efficiency of about 190% for the sample containing 19% of rare earths.

Biopolymers from Composted Biowaste as Stabilizers for the Synthesis of Spherical and Homogeneously Sized Silver Nanoparticles for Textile Applications on Natural Fibers.

The use of bio-based substances (BBS) obtained from composted biowaste as stabilizers for the production of silver nanoparticles (AgNPs) in substitution to citrate is investigated herein, evaluating the functionalization of natural fibers for textile antibacterial applications. The results obtained evidenced that BBS can substitute citrate as reducing/stabilizing agent in the synthesis, inducing a geometrical control (in shape and size) of the AgNPs. Two different substrates were selected (wool and cotton) and two dip-coating deposition techniques investigated. The release of AgNPs from the supports in water was evaluated under two different experimental conditions: 1) soaking (static conditions) for 7 and 15 days, simulating the contact with sweat, and 2) centrifugation (dynamic conditions), simulating a washing machine treatment. A wide physicochemical characterization was carried out to evaluate the effects of BBS on the morphology and stability of AgNPs suspensions as well as the functionalization effectiveness.

Effect of trivalent rare-element doping on structural and optical properties of SnO2 thin films deposited by dip coating deposition technique

Erbium doped tin oxide thin films (SnO2:Er) were prepared by the sol–gel method using dip coating technique. X-ray diffraction patterns showed a decrease of crystallinity in the films with increase in erbium doping concentration (0–5 mol%). Scanning electron microscopy analysis revealed an inhibition of grain growth with increase in erbium doping concentration. The film surfaces were uniform with crack free appearance. X-ray photoelectron spectroscopy revealed the presence of erbium, oxygen, tin oxide in the SnO2:Er films. The resistivity of the SnO2:Er films decreased and then increased with the increase in erbium doping concentration. The optical properties of the films have been studied from transmission spectra. An average transmittance of 80 % in ultraviolet–visible region was observed for all the films. Optical band gap energy (Egap) of SnO2:Er films were observed to increase with the increase in doping concentration. Photoluminescence spectra of the films exhibited an increase in the emission intensity for (0–3 mol%) and decreased for 5 mol% erbium doping film. Such SnO2:Er films with wide band gap and luminescence efficiency are applicable in blue and ultraviolet optical devices, such as light-emitting diodes and laser diodes.

Cadmium Telluride (CdTe) Thin Film for Photovoltaic Applications

Cadmium telluride (CdTe) thin films are prepared by the dip-coating deposition technique under atmospheric pressure at different temperature. The optical band gap obtained within the range 1.63-1.60 eV. Crystallite sizes are obtained from XRD that are dependent on composition (Cd/Te) and baking temperatures. Raman spectra confirms the presence of transverse (TO) and longitudinal (LO) optical phonons in the CdTe structure. Films are good photoconductive in nature and could be used in photovoltaic applications. Index Terms—CdTe, optical band-gap, photoconductivity. I. I NTRODUCTION The interest on the different properties of photonic CdTe material is of considerable, due to its practical importance in technological applications such as, integrated optics, optoelectronics, solar energy conversion, gamma ray detection, and x-ray imaging. CdTe is of low cost thin film photovoltaic cells because of its direct band gap and have high absorption coefficient. CdTe could be doped with both n- and p- type materials using a large number of of preparation methods / techniques such as vacuum deposition (1), electro-deposition (2), (3), molecular beam epitaxial (4), metal-organic chemical vapour deposition (5), (6), close-space sublimation (7), (8) and screen printing (9), (10). It is necessary to have a detailed understanding of the basic properties of the materials for the fabricating the photovoltaic applications. In this present work we focuses on the basic and fundamental properties like optical, structural and photoconductive response of CdTe thin films grown by the dip-coating for the photovoltaic applications.

Electrophoretically-Assisted Deposition of Mesoporphyrin IX on Nanoparticulate TiO2 Films for Constructing Efficient Dye-Sensitized Solar Cells

The successful fabrication of efficient dye-sensitized solar cells containing electrophoretically-deposited mesoporphyrin IX in semiconductor films based on sintered TiO2 nanoparticles is presented in this work. For comparison purposes, photocells utilizing mesoporphyrin IX-sensitized TiO2 electrodes were also constructed following the traditional dip-coating deposition technique. Electrochemical responses obtained from these modified surfaces revealed that the electrophoretic methodology generated perpendicularly-arranged porphyrin layers on the sintered oxide nanoparticles, while the dip-coating deposition technique resulted in parallel layers of porphyrin. It was demonstrated that the photovoltaic performance of cells containing electrophoretically-dyed TiO2 films was three times higher than that of devices having photoelectrodes constructed according to the dip-coating protocol. To better understand this behavior, both types of solar cells were further investigated by means of photoelectrochemical impedance spectroscopy.

Superhydrophilicity and photocatalytic property of nanocrystalline titania sol–gel films

Nanocrystalline titania thin films were prepared by deposition and annealing of titania sol–gel precursor materials, both non-hydrated solutions and hydrosols. The sol–gels were immobilized on glass substrates applying doctor blade and dip-coating deposition techniques. The nanoparticle size, determined by the full-width at half-maximum of the X-ray diffraction peaks as well as by shifting and broadening of the Raman modes, strongly depends on the precursor solution. Significant differences were also confirmed on the surface characteristics, roughness and complexity of the films by atomic force microscopy. The films present high activity towards photodecomposition of methyl orange azo-dye together with enhanced photo-induced superhydrophilicity under illumination with ultraviolet light. Judicious choice of the precursor material and efficient control of the deposition parameters may lead to the optimization of their photocatalytic and/or superhydrophilic properties.

Electrochromic and Ex Situ IR and Raman Spectroelectrochemical Studies of LixInVO4 Films Charged/Discharged in the 0 < x < 1 Domain

films were prepared using the sol-gel route from V-oxoisopropoxide and In-nitrate precursors. Films were made by dip coating deposition technique which allows the preparation of films with a thickness up to 230 nm by a single dipping cycle. The structure of crystalline films obtained at 500°C was investigated using Raman and IR spectroscopies, which were combined with X-ray diffraction. The crystalline films consist of a monoclinic phase with an admixed orthorhombic phase. Electrochemical investigations revealed that the charge capacity of the crystalline films (500°C) is about −40 mC significantly exceeding the ion storage capacity of amorphous films prepared at 300°C (−20 mC In situ UV-visible spectrolectrochemical studies of amorphous and crystalline films showed that the coloration of the films is cathodic with a change in a photopic transmittance from 0.034 to 0.149, respectively. Crystalline films exhibit higher coloring than amorphous films; this is related to their higher coloration efficiency The main focus is given to IR and Raman spectroelectrochemical studies of crystalline films (500°C) galvanostatically charged in the domain Vibrational spectra revealed that the monoclinic phase remains unchanged in the domain and transforms to the amorphous phase when charged in the domain. Vibrational band changes observed in Raman and IR spectra of charged and discharged films are assessed and correlated with the spectral features of and films studied previously. © 2001 The Electrochemical Society. All rights reserved.

Structural and spectroelectrochemical investigations of tetragonal CeVO 4 and Ce/V-oxide sol-gel derived ion-storage films

Thin films of CeVO 4 prepared via the sol-gel route, with a tetragonal (I4 1/amd) crystalline structure, show good ion-storage properties. The sol-gel route combined with the dip-coating deposition technique allowed thin solid films and powders with a specific Ce/V molar ratio (Ce/V=2:1, 1:1 (CeVO 4), 1:2) to be made. The structure of films and powders prepared at 400°C, and at different times of heat-treatment, was determined using X-ray diffractometry (XRD). It is shown that films containing more ceria than vanadia (Ce/V>1) are nanocrystalline with a CeO 2 grain size up to 100 Å, but a tetragonal CeVO 4 (Wakefieldite) phase is formed when the Ce/V molar ratio is 1:1. By using cyclic voltammetry it was possible to observe the Ce 4+/Ce 3+ and V 5+/V 4+ redox changes occurring in the films, while in-situ UV-VIS spectroelectrochemical measurements confirmed the sole presence of V 5+/V 4+ redox changes in tetragonal CeVO 4 films. The small (∼0.1–0.5 cm 2/C) coloration efficiency of CeVO 4 films suggests their utilization as counter electrodes in electrochromic (EC) devices. Comparison of the IR transmission spectra of as-deposited CeVO 4 with CeVO 4 films charged to x≅0.9 revealed that besides A 2u and E u modes – attributed to the VO 4 3− stretching vibrations predicted by factor group analysis, the Raman active E g and B 2g modes appear in IR spectra. This suggests that inserted Li + ions occupy the accessible sites within the structure resulting in the loss of inversion symmetry and the consequent disappearance of the distinction between g and u modes. Charging to x≅2.3 causes instability of the film structure.