SILAR Deposition Research Articles

In-doped ZnO films deposited by modified SILAR method for enhanced ethanol gas sensor application

The rapid and skillful detection of toxic gases is a crucial requirement for the advancement of gas sensors. In this study, we fabricated undoped and In-doped (1 %, 3 %, and 5 % by weight) ZnO films using a two-step modified SILAR deposition technique. The ethanol gas sensing properties of both undoped and In-doped ZnO films were examined across a range of operating temperatures (from room temperature, 27 °C–200 °C) and concentrations (1 ppm–50 ppm). Of all the films, those doped with 5 % Indium exhibited the most stable, reproducible, and highest response, achieving 86.27 % at 50 ppm ethanol at an operating temperature of 100 °C. Compared to the undoped ZnO films, all Indium-doped ZnO films demonstrated significantly shorter response times (17 s) and recovery times (19 s). The response of all the deposited films to various gases such as acetone, methanol, toluene, xylene, and formaldehyde was lower than their response to ethanol. The mechanism behind the enhanced sensing characteristics of the Indium-doped ZnO films is explored. Additionally, the impact of humidity on sensor performance was investigated. This study reveals that 5 % In-doped ZnO films hold great potential as materials for ethanol gas sensing applications.

SILAR deposition and characterization of ZnO films for numerical investigation as electron transport layer in solar cells

The SILAR method of thin film deposition has attracted the scientific community over the years due to its easiness, low cost, availability of room temperature deposition, and more over due to the variation in properties of thin films available by varying deposition parameters.This work is carried out in a way to comprehensively compare two ZnO thin film samples prepared from precursor media with Zinc Acetate (S1) and Zinc Chloride(S2) salts deposited by SILAR method in Perovskite Solar cell applications. The XRD, FTIR, Raman, FESEM, and UV-Visible analysis were carried out for identifying the structural, morphological, and optical quality of these samples. The role of these samples as Electron Transport Layer (ETL) in Perovskite Solar cell were identified using General purpose PhotoVoltaic Device model (GPVDM) simulation software which is well adapted for studying Solar cell architecture. It provided the output Solar cell parameters like Jsc, Voc, FF, PCE, etc and by varying the active layer and Hole Transport Layer (HTL) thicknesses, the optimized efficiency of devices with samples S1 and S2 were obtained as 21.88% and 21.96%.The results showed that SILAR-synthesized ZnO thin films could be potential candidates for ETL applications in Perovskite Solar cells.

The construction of TiO2 NTs/Ag3PO4–AgBr by SILAR deposition as promising photocatalysts for hydrogen production and pollutant treatment

The construction of ternary TiO2 NTs/Ag3PO4–AgBr photocatalysts was carried out by the SILAR deposition of Ag3PO4 and AgBr on TiO2 nanotube arrays (TiO2 NTs) for enhancing the photocatalytic application in H2 evolution and dyeing wastewater remediation. The adjustment of Ag3PO4/AgBr deposition cycles was used to optimize the optical absorption and photocatalytic property. The TiO2 NTs/Ag3PO4–AgBr (5) prepared with 5 cycle deposition of Ag3PO4 and AgBr exhibited the optimal photoelectric activity and photocatalytic performances. The photocatalytic rate constants for the degradation of MO, RhB and MB dyes achieved 1.35 × 10−2, 3.30 × 10−2 and 4.47 × 10−2 min−1, respectively, and the visible light-driven photocatalytic H2 evolution rate achieves 46.87 μmol cm−2 h−1. •O2− radicals exhibited the key influence on the organic dye degradation, and the as-prepared photocatalysts showed exceedingly high photocatalytic activity and stability. Furthermore, the photocatalytic mechanism was proposed based on the ESR result.

Improving loading of CdS/CdSe co-sensitized quantum dots to enhance the performance of solar cells by voltage-assisted SILAR deposition

Improving loading of CdS/CdSe co-sensitized quantum dots to enhance the performance of solar cells by voltage-assisted SILAR deposition

Photocatalytic degradation of model pollutants using ZnO/Ag3PO4 heterostructure thin films under visible and solar irradiation

ZnO/Ag3PO4 heterostructure-based thin films were prepared by hydrothermal and SILAR deposition processes. The prepared samples were characterized for their morphology, structure, and optical properties using SEM, XRD, EDS, UV–Vis spectroscopy, and PL spectroscopy. Ag3PO4 modifies the light absorption characteristics significantly, with a considerable absorbance in the visible region found for ZnO. Under visible light and sunlight irradiation, Ag3PO4–ZnO nanorod-based heterostructure displayed substantially more substantial photocatalytic activity toward MB degradation, as well as superior recyclability and stability than pure ZnO nanorods. The Ag3PO4–ZnO nanorod combination with a 5 times dip of Ag3PO4 had the excellent photodegradation efficiency of MB (86%) compared to pure ZnO nanorods (60%) under visible irradiation.

Tuning PL emission energy and bandgap with Ni dopant of MgO thin films

In this study, for the first time, the effect of Nickel (Ni) additive on Magnesium oxide (MgO) thin films produced by using successive ionic layer adsorption and reaction technique (SILAR) was investigated. Absorption, photoluminescence (PL), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) measurements were executed to examine how the optical, structural and morphological properties of the samples were affected by the addition of Ni. In the absorption analysis, it was noted that the band gaps of the MgO samples decreased from 4 eV to 3.5 eV with the increase of Ni dopant concentrations. Also, the transmittance values of MgO nanostructures decreases with the increase of Ni contribution, and in the same way, the reflection measurements show that the reflection of MgO decreases with the increase of Ni doping. PL measurements revealed that the fabricated structures radiate around 410 nm and 730 nm. According to XRD measurements, besides the cubic structure of the samples, NiO formations were detected inside the MgO thin film samples due to the increase in Ni dopant. XPS measurements have proven the presence of Ni doping in MgO. SEM measurements showed that all samples exhibited nanowall structure. All these results demonstrate that Ni doping on MgO thin films can be achieved by using SILAR deposition technique.

SILAR deposition of bismuth vanadate photoanodes for photoelectrochemical water splitting

Bismuth vanadate coatings are fabricated via a sequential solution-based method and used as photoanodes for water oxidation achieving exceptional performances.

Voltage-assisted SILAR deposition of CdSe quantum dots to construct a high performance of ZnS/CdSe/ZnS quantum dot-sensitized solar cells

The charge recombination on the interfaces of TiO2/quantum dots (QDs)/electrolyte is a key factor limiting the efficiency of quantum dot-sensitized solar cells (QDSSCs). Construction of double-layer barrier structure of ZnS/QDs/ZnS is a vital strategy to suppress the interfacial charge recombination. However, a large lattice mismatch (12%) at CdSe/ZnS interfaces causes CdSe to grow slowly on TiO2/ZnS mesoporous film, weakening the interaction between QDs and mesoporous film, which reducing the efficiency of CdSe QDSSCs with double ZnS barrier layers. Applying a voltage of 2 V in successive ionic layer adsorption reaction (VASILAR) to create an electric field, which assists Cd2+ and SeSO32− ions rapidly diffuse into the TiO2/ZnS mesoporous film to react forming CdSe QDs at room temperature. Optimizing the number of CdSe QDs deposition layers and combine with ZnS double-layer barrier structure, a best PCE of 4.34% for ZnS/CdSe/ZnS QDSSCs is achieved. This study gives a fast and simple approach to inhibit interfacial charge recombination to construct high performance CdSe QDSSCs.

Exploring the optical properties of lead zinc sulfide photoanodes for optoelectronics

In this study, the optical properties of alloyed lead zinc sulfide quantum dots (Pb0.8Zn0.2S QDs) photoanodes have been explored for optoelectronic applications. The alloyed QDs photoanodes were prepared by SILAR technique for different deposition cycles (0–8 times). Transmission electron microscope (TEM) and energy dispersive X-ray spectrometer (EDS) were used to investigate the morphological and elemental measurements respectively. A UV–visible spectrophotometer was utilized to study the optical properties. The obtained energy band gap (Eg) values of the prepared photoanodes vary from 1.98 to 3.32 eV as the number of the deposition cycles is increased from 1 to 8 times. The best photovoltaic performance of the assembled QDs sensitized solar cells (QDSSCs) is achieved for the 6 times SILAR deposition cycles. This result is mainly attributed to the absorption enhancement and the harmony of the energetic alignment levels of the prepared QDSSC’s layers. The prepared alloyed photoanodes could be novel candidates in many optoelectronic applications.

EFFECT OF CYCLE COUNT IN SILAR DEPOSITION OF COUNTER ELECTRODE ON THE PERFORMANCE OF QUATERNARY QUANTUM DOT SENSITIZED SOLAR CELL

Cu-Ni-S alloyed films of different thicknesses were prepared by varying the number of cycles in SILAR deposition and were used for the application as Counter Electrode in QDSSCs. For device fabrication, titanium dioxide films were used as a photo-anode layer, Cu2ZnSnS4 quaternary quantum dots as a sensitizer, and polysulfide electrolyte was used as Redox mediator. The effect of number of SILAR cycles on the electrical and electrochemical parameters was studied with V-I characteristic curve and electrochemical impedance spectroscopy. The device incorporating counter electrode deposited by 10 SILAR cycles performed best among other devices because of its lowest impedance parameters.

Enhancement of photocatalytic and photoelectrochemical properties of TiO2 nanotubes sensitized by SILAR - Deposited PbS nanoparticles

The aim of this work is to improve the photocatalytic and photoelectrochemical properties of TiO2 nanotubes (TiO2-NTAs) by sensitizing them with PbS nanoparticles (NPs) prepared by the Successive Ionic Layer Adsorption and Reaction method (SILAR). The Microstructure, surface morphology, phase composition and optical properties of the prepared structure were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM and High-resolution mode HRTEM) and X-ray photoelectron spectroscopy (XPS). The TiO2 NTAs were loaded by PbS NPs, which contents increase by increasing the number of SILAR cycles. The PbS NPs, which have a size in the order of ∼20 nm, were found to be uniformly distributed in the TiO2 NTAs without damaging the tubular ordered structure. The photocatalytic activity of the PbS/TiO2 NTAs system, toward Amido Black (AB), showed significant enhancement compared to the bare untreated TiO2 NTs. At 30 SILAR deposition cycles the PbS-NPs/TiO2 NTAs structure is able to remove 75% of BA under simulated solar light, considerably higher than the 40% removal obtained with unloaded TiO2 NTAs. A significant improvement of the Photoelectrochemical (PEC) efficiency has been also demonstrated for the PbS-NPs/TiO2 NTAs hybrid system. This improvement is mainly related to visible-light harvesting and reduced recombination of photo-generated electron-hole pairs due to the synergistic effect of the heterojunction and to the well-organized morphology of the TiO2 NTAs.

Effect of Surface Modification on SILAR Deposited CdS Quantum Dot Sensitized Hydrothermally Synthesised Titania Nanostructure

In the present work titaniana noflakes-nanorods were prepared on a flexible titanium metal foil by modified hydrothermal method. The titania nanoflakes-nanorods were further sensitized with CdS quantum dots through SILAR deposition. The surface charge of the titania surfaces were tuned using triethanolamine (TEA) to obtain maximum loading of CdS particles on the surface. The samples were characterized by XRD, FE-SEM and EDX analysis, which confirms the enhanced deposition of CdS quantum dots on the titania surface by TEA modification. The visible light photocatalytic studies were done by methylene blue degradation study. The modification in the SILAR cycle using TEA improves the photocatlytic performance around 4 times than those without TEA. The OH.radical formed in the photocatalytic reaction followed by photoluminescence study.

α-Fe2O3 Nanoparticles as a Byproduct from the Thin Film (SILAR) Deposition Process: A Study on the Product

α-Fe2O3 nanoparticles were synthesized from residual bath of SILAR deposition of Iron oxide thin films. The product was calcinated at 200, 400 and 600°C and characterized for its quality using XRD, FTIR, UV-Vis-DRS, PL, HRTEM and VSM. XRD results confirm the formation of α-Fe2O3. nanoparticles. Uniform spherical morphological particles formation was observed from HRTEM. Obtained particles exhibit spin canted-ferromagnetic behavior. All characterization results ensure the quality of α-Fe2O3 nanoparticles as a byproduct from the residual bath.

Properties of SILAR deposited magnetite (Fe3O4) thin films: effect of bath temperatures

Magnetite thin films were deposited by varying the temperature of the bath in the SILAR deposition process. Structural, morphological and optical properties of the deposited films were analyzed using X-ray diffraction, Raman spectroscopy, Field emission scanning electron microscopy, UV–Visible spectroscopy. With the increase in bath temperature of the deposition process, crystallite size decreases and dislocation density and microstrain increases. Raman spectra confirm the formation of magnetite phase for all the deposited films. FESEM images reveal the bath temperature’s influence on the surface morphology. Considerable variations in the optical properties were observed for the films and were discussed in detail.

CdS for TiO2-based heterostructures as photoactive anodes in the photoelectrochemical cells

CdS nanoparticles (0D) were deposited using the SILAR method on the surface of titanium foil (2D), TiO2 thin films (2D) and flower-like nanostructures (NF) of TiO2 (3D). Flower-like TiO2 was gown using chemical oxidation in a 30% H2O2 solution. SEM analysis was performed to evaluate the influence of the SILAR deposition parameters and roughness of the substrate on the alignment and size of CdS. The analysis of XRD and Raman data revealed a mixture of anatase and rutile in different ratios for NF and a mixture of cubic and hexagonal polymorph for CdS. UV–vis–NIR spectrophotometry showed fundamental absorption edges originating from both TiO2 (3.19–3.37 eV) and CdS (2.52–2.80 eV). The band gap energy of CdS was found to be blue-shifted. The values of photocurrent–voltage characteristics registered in a photoelectrochemical cell (PEC) were dependent by the parameters of SILAR deposition process. It was demonstrated that photoanodes based on TiO2/CdS heterostructures offer far better performance in PECs than those based on TiO2.

Synthesis and characterization of ZnO thin film by low cost modified SILAR technique

The ZnO thin film is prepared on Fluorine Tin Oxide (FTO) coated glass substrate by using SILAR deposition technique containing ZnSO₄.7H₂O and NaOH as precursor solution with 150 deeping cycles at 70 °C temperature. Nanocrystalline diamond like ZnO thin film is characterized by different characterization techniques such as X-ray diffraction (XRD), Fourier transform (FT) Raman spectrometer, Field Emission Scanning Electron Microscopy (FE-SEM) with Energy dispersive X-Ray Analysis (EDAX), optical absorption, surface wettability and photoelectrochemical cell performance measurement. The X-ray diffraction analysis shows that the ZnO thin film is polycrystalline in nature having hexagonal crystal structure. The FT-Raman scattering exhibits a sharp and strong mode at 383 cm⁻¹which confirms hexagonal ZnO nanostructure. The surface morphology study reveals that deposited ZnO film consists of nanocrystalline diamond like morphology all over the substrate. The synthesized thin film exhibited absorption wavelength around 309 nm. Optical study predicted the direct band gap and band gap energy of this film is found to be 3.66 eV. The photoelectrochemical cell (PEC) parameter measurement study shows that ZnO sample confirmed the highest values of, short circuit current (I_sc - 629 mAcm⁻²), open circuit voltage (V_oc - 878 mV), fill factor (FF - 0.48), and maximum efficiency (η - 0.89%), respectively.

Photoelectrochemical performance of ZnCdSe-sensitized WO3 thin films

Due to its wide gap, WO3 mostly absorbs only the ultraviolet radiation, resulting into lower charge collection and thus necessitating the coupling (doping or sensitization) of WO3 with low band gap materials so as to achieve the photoexcitation and charge separation. This study reports the sensitization of WO3 films with ternary quantum dots (ZnCdSe) using SILAR technique for the first time. The porous WO3 layer was spray deposited using ammonium metatungstate as precursor. The structural, surface morphological and optical properties of the sensitized WO3 thin films were studied. Photoelectrochemical (PEC) studies of the sensitized films showed superior performance to that of unmodified WO3 films. Photocurrent density of 8.53mA/cm2 (at 0V vs Ag/AgCl) was observed for film sensitized with 9 cycles of SILAR deposition annealed at 400°C under nitrogen atmosphere, which is a 120-fold and 14-fold increase in photocurrent density when compared to unsensitized WO3 film and WO3/TiO2 film, respectively. Sensitization with ternary quantum dots as ZnCdSe thus offers two advantages: (i) the lower band gap of ZnCdSe allows it to absorb more energy and in turn produce more charge carriers and (ii) the conduction band of ZnCdSe, which lies above the conduction band of TiO2, results in a better charge transfer from sensitizer to the substrate material.

Effect of the Nature of Cadmium Salts on the Effectiveness of CdS SILAR Deposition and Its Consequences on the Performance of Sensitized Solar Cells

Nanocrystalline titania films deposited on FTO transparent electrodes were sensitized by CdS nanoparticles synthesized in situ by the SILAR method. Three precursor solutions were employed for adsorption of Cd2+ ions: nitrate, sulfate, and acetate. The CdS load and the size of CdS nanoparticles varied a lot from one precursor to the other. The highest load and the largest nanoparticles were obtained in the case of cadmium acetate, the smallest in the case of nitrate, while sulfate gave intermediate values. Ultraviolet photoelectron spectroscopy was employed to measure the ionization potential (and valence band potential) for pure titania and for sensitized titania in the three cases. The obtained values were 7.4 eV for pure titania and 6.7, 6.6, and 5.7 eV for CdS-sensitized titania made by using cadmium nitrate, sulfate, and acetate precursors, respectively. The corresponding band gap values ranged between 2.5 and 2.3 eV. The thus characterized photoanodes were employed to make Quantum Dot Sensitized Sola...

Influence of deposition parameters on the structural and optical properties of CdS thin films obtained by micro-controlled SILAR deposition

Polycrystalline CdS films were obtained by a micro-controlled SILAR deposition technique, using aqueous solutions of cadmium acetate and thiourea as precursors. The structural and optical properties of the films were found to be influenced by various deposition parameters such as number of immersion cycles, concentration of the precursors and temperature of the solutions. Contrary to the observations made by some researchers, we found that the thickness of the films increased continuously with number of immersion cycles and also with concentration of the precursor solutions. We also found that the films covered the substrates uniformly, without any voids, unlike the films obtained by others. Effect of deposition parameters on thickness, substrate coverage, grain size, chemical composition, optical band gap and other properties of the films is discussed in detail.

Sensitization of TiO2nanotube array photoelectrodes with MnxCdySe

The photoanode obtained by the deposition of MnxCdySe nanocrystals onto TiO2 nanotube arrays using a successive ionic layer adsorption and reaction technique realized a significant improvement in the charge transport and current generation compared with a pristine TiO2 nanotube based anode. The concentration of manganese was determined to be 10% of the concentration of cadmium, and thus x = 0.1y. The widening of absorption spectra and the magnitude of photocurrent density were found to be significantly affected with a variation in the number of SILAR cycles and the annealing temperature. A stable photocurrent density of ∼8 mA cm−2 under AM 1.5 illumination (1 sun) was achieved for MnxCdySe nanocrystals-embedded TiO2 nanotube arrays heterostructure based photoelectrodes prepared through 9 cycles of SILAR deposition, followed by annealing at 400 °C under a nitrogen atmosphere. The results obtained suggest the versatility of the MnxCdySe-sensitized TiO2 nanotube matrix as an efficient electrode for photovoltaic applications.