Papers by Keyword: SILAR Method

Abstract: This study reports on the amperometric sensing properties of FeO/Fe₂O₃ thin films for the detection of Allura Red (AR) and Direct Blue 15 (DB15) Azo dyes. The FeO/Fe₂O₃ thin films were produced using the Sequential Ionic Layer Adsorption and Reaction (SILAR) method and Na⁺-doping. The morphological and structural properties of the nanocomposites produced at pH of 10.5 showed good properties for the detection of azo dyes. The linear curve fit equations for AR and DB15 droplet applications onto Na⁺-doped FeO nanocomposite thin film samples were found to be y = -0.0002x + 0.0043 (R² = 0.9143) and y = -7E-05x + 0.0005 (R² = 0.9809), respectively. The findings reveal that adding Na⁺ doping to FeO/Fe₂O₃ thin films can effectively increase the detection response for the target azo dyes and enhance the sensitivity of the sensing system. The results suggest that the SILAR method can be used to produce low-cost and reusable FeO/Fe₂O₃ thin film devices, which can be promising candidates for the detection of toxic azo dyes in liquid samples.

Abstract: Heterostructured semiconductors are considered one of the most significant candidates for photoelectrochemical cells (PECs) water splitting because of their visible photovoltaic features. Hence, this study displayed the synthesis of Ag₂S NPs/ZnO nanorods arrays (NRAs) as a function of annealing temperature in the range between 100 °C and 500 °C. The heterostructured photoanode was fabricated through two- simple steps synthesis; the first one was hydrothermal method (HT) and the second one successive ionic layer adsorption and reaction (SILAR) method. Structural morphology characteristics, chemical conformation and properties of synthesized nanostructure were studied via different characterization techniques such as field emission scanning electron microscopy (FE-SEM), X-ray diffraction spectroscopy (XRD), HR-TEM and EDX, correspondingly. The XRD results showed that the hexagonal phase of ZnO NRAs combined successfully with monoclinicAg₂S nanoparticles. The optical properties throughout absorbance spectra disclosed that with increasing the annealing temperature, the absorbance edges shifted toward extended wavelength indicating considerable enhancement in the optical properties upon the heat -treatment. Additionally, Ag₂S nanoparticles/ZnO NRAs was employed as a working photoanode in photoelectrochemical cell consists of three-electrodes configuration. The result showed an important improvement in the performance of photoelectrochemical cell. It was observed that Ag₂S/ZnO NRAs upon annealing at 400 °C showed an impressive photocurrent density, photoconversion efficiency of 2.73 mA/cm² and 2.33%, respectively by achieving ~8 times higher compared to ZnO NRAs (0.337 mA/cm²). Such this enhancement was attributed to the morphological structure improvement, crystallinity and optical properties enhancement of the heterostructured photoanode after the conducting annealing process.

Abstract: This work deals with the deposited cadmium sulfide (CdS) quantum dots thin films on transparent conductive fluorine-doped tin oxide (FTO) substrates prepared by successive ionic layer adsorption and reaction technique (SILAR). QD deposition based on SILAR is easy, cheap and effective method which improves the surface quality and performance of QD-based devices. The effect of the number of cycles of SILAR on the morphology and size of the quantum dots has been investigated. SILAR technique was adopted for the deposition of CdS on anatase TiO₂ and the three main factors contributing to the performance of QDs processed by SILAR, namely the number of cycles used, the concentration of the precursor solution, and the reaction dipping time, are discussed. The structural, morphological and optical properties were studied using X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), Raman spectra analysis and UV-Vis NIR analysis, respectively. The particle size of CdS was calculated from XRD pattern using Debye Scherrer’s equation and the calculated particle size was 4.5-9.5 nm. Using CdSQDs, quantum dot sensitized solar cells (QDSSC) were fabricated on FTO substrates as being a transparent conductive oxide. Optical absorption property proved that the band gap energy value was about 2.44 eV. The result delivered from J-V curve revealed that the overall energy conversion efficiency increased with increasing the deposition cycles giving the best efficiency of 2.73 % at 7 cycles.

Abstract: Titanium dioxide (TiO₂) nanoparticles thin film has been successfully prepared by a simple hydrothermal process using Hydrochloric Acid (HCl) as chelating agent and Titanium (IV) Chloride (TiCl₄) as precursor. In this study, the nanostructured TiO₂ thin films were prepared at different hydrothermal reaction times of 2 hours, 5 hours, and 10 hours, and then Ag₂S Quantum Dots (QDs) were deposited on the surface of TiO₂ nanoparticles using 6 cycles of Successive Ionic Layer Adsorption and Reaction Deposition (SILAR) method. The surface morphology, crystalline structure and optical characterizations of the films were carried out using Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscope (AFM), X-ray Diffraction (XRD) and Ultra-Violet-Visible Near Infrared Spectrophotometer (UV-Vis). For electrical properties, four-point probe investigated the sheet resistance, resistivity, and conductivity of these thin films. TiO₂ nanorods were formed with diameter ranged from 33.78 nm to 42.58 nm and the length of TiO₂ layer increased as the reaction time increased, from 2.84 μm to 3.93 μm (without Ag₂S QDs) and 2.88 μm to 4.85 μm (with Ag₂S QDs). When the reaction time reaches 10 hours, nanoflowers can be seen on the surface of film. The XRD results showed that with longer reaction time, the value of full-width at half maximum (FWHM) of the TiO₂/ Ag₂S QDs thin films decreased from 0.335° to 0.263 while the crystallite size increased from 22.73 nm to 35.39 nm. UV-Vis analysis indicated that the optical band gap of these thin films decreased from 2.68 eV to 2.00 eV (direct) and 2.94 eV to 2.40 eV (indirect) with increased in reaction time. The electrical properties of the films showed that the resistivity varied between 7 x 10⁷ Ω.cm and 5.07 x 10⁷ Ω.cm when the reaction time changed from 2 hours to 10 hours. The conductivity of the TiO₂/ Ag₂S QDs thin films increased with the increase in hydrothermal reaction time and further increased with the incorporation of Ag₂S QDs. Besides, the TiO₂ films synthesized hydrothermally for 10 hours showed higher surface roughness as compared to other thin films. The obtained results showed that the TiO₂ / Ag₂S QDs thin films are applicable as a photoanode for Quantum Dots Sensitized Solar Cell (QDSSCs) applications.

Abstract: As a promising absorber layer, semiconducting Cu₂ZnSnS₄ (CZTS) can be applied to replace the organic dye in dye-sensitized solar cell for photovoltaic application because of its good stability, suitable band gap energy (~1.5eV) and large absorption coefficient (~10⁴ cm^-1). In this paper, successive ionic layer adsorption and reaction (SILAR) method was utilized to deposit CZTS nanoparticles on mesoporous titanium dioxide (TiO₂). This solar cell with carbon film coated FTO glass slide as the back electrode showed an open circuit voltage of 380 mV. Preliminary results obtained for solar cells fabricated with this material are promising.

Abstract: ZnO nanorods (NRs) have been synthesized by a chemical bath deposition (CBD) method on simple glass substrate that had been precoated by successive ionic layer absorption and reaction (SILAR) with a thin ZnO film. ZnO NR array was obtained by using zinc acetate and hexamethylenetetramine as aqueous solutions at optimized pH concentration and deposition time. X-ray diffraction (XRD) and SEM analysis were used to confirm the growth of ZnO nanorods. The pH and deposition time of the solution was found to influence the growth behavior of ZnO NRs. PL analysis also reflected the growth behavior of ZnO NRs.

Abstract: CuInS2 thin films were deposited on galss substrate by successive ionic layer absorption and reaction (SILAR) method at room temperature. CuCl2, InCl3, and Na2S were used as precursor materials. The thin films were obtained during the dipping of 20-40 cycles and after annealing in the N2 atmosphere at 500°C. The characterization of the film was carried out by X-ray diffraction, scanning electron microscopy, optical absorption spectrum and X-ray photoelectron spectra. Quantification of the XPS peaks shows that the molar ratio of Cu:In:S of the film is close to the stoichiometry of CuInS2. XRD result demonstrated that the formed compound is CuInS2 with chalcopyrites crystal structure. Direct band gap was found to be 1.5eV from optical absorption spectrum.