Showing papers on "Chemical bath deposition published in 2018"

Low-Temperature Nb-Doped SnO2 Electron-Selective Contact Yields over 20% Efficiency in Planar Perovskite Solar Cells

Abstract: Low-temperature planar organic–inorganic lead halide perovskite solar cells have been at the center of attraction as power conversion efficiencies go beyond 20%. Here, we investigate Nb doping of SnO2 deposited by a low-cost, scalable chemical bath deposition (CBD) method. We study the effects of doping on compositional, structural, morphological, and device performance when these layers are employed as electron-selective layers (ESLs) in planar-structured PSCs. We use doping concentrations of 0, 1, 5, and 10 mol % Nb to Sn in solution. The ESLs were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, and ultraviolet–visible spectroscopy. ESLs with an optimum 5 mol % Nb doping yielded, on average, an improvement of all the device photovoltaic parameters with a champion power conversion efficiency of 20.5% (20.1% stabilized).

Mixed Sulfur and Iodide-Based Lead-Free Perovskite Solar Cells

Abstract: The use of divalent chalcogenides and monovalent halides as anions in a perovskite structure allows the introduction of 3+ and 4+ charged cations in the place of the 2+ metal cations. Herein we report for the first time on the fabrication of solar cells exploiting methylammonium antimony sulfur diiodide (MASbSI2) perovskite structures, as light harvesters. The MASbSI2 was prepared by annealing under mild temperature conditions, via a sequential reaction between antimony trisulfide (Sb2S3), which is deposited by the chemical bath deposition (CBD) method, antimony triiodide (SbI3), and methylammonium iodide (MAI) onto a mesoporous TiO2 electrode, and then annealed at 150 °C in an argon atmosphere. The solar cells fabricated using MASbSI2 exhibited power conversion efficiencies (PCE) of 3.08%, under the standard illumination conditions of 100 mW/cm2.

Improved Hydrogen Evolution Reaction Performance using MoS2–WS2 Heterostructures by Physicochemical Process

Abstract: This report describes the synthesis of a layered molybdenum disulfide (MoS2)–tungsten disulfide (WS2) heterostructure onto fluorine doped tin oxide covered glass substrates using a combination of chemical bath deposition and RF sputtering techniques. FESEM images revealed that the MoS2–WS2 heterostructure surface consisted of a cauliflower structured array of grains with spherical structures. The vertically aligned atomic layers were explored by transmission electron microscopy images for MoS2–WS2 heterostructure. Hydrogen evolution reaction (HER) kinetics show overpotentials of 151 and 175 mV @ 10 mA/cm2 with Tafel slope values of 90 and 117 mV/decade for pristine MoS2 and WS2 electrocatalysts, respectively. Improved electrocatalytic activity for HER was established with overpotential 129 mV @ 10 mA/cm2 and Tafel slope 72 mV/decade for the MoS2–WS2 heterostructure. The MoS2–WS2 heterostructure electrocatalyst showed robust continuous HER performance over 20 h in an acidic solution. This improved electroc...

Fabrication, characterization and photoelectrochemical activity of tungsten-copper co-sensitized TiO 2 nanotube composite photoanodes

Abstract: Tungsten-copper co-sensitized TiO2 nanotube films on titanium substrate, used as photoanodes in photoelectrochemical (PEC) water splitting to produce hydrogen, have been synthesized via anodization and chemical bath deposition (CBD) methods. Field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) were used to study the morphology and elemental composition of the synthetic samples. UV-Vis diffuse reflection spectroscopy (UV-Vis DRS) was sued to investigate the optical features of the samples. The impact of copper and tungsten ratio on the photocatalytic behavior of co-sensitized TiO2 nanotube photoelectrodes in PEC water splitting has been investigated. High photocatalytic activity has been exhibited by the co-sensitized TiO2 nanotube samples due to the synergistic effects of the copper and tungsten. Sample T4 had the highest photoelectrochemical activity compared with other samples. In addition, this sample exhibited outstanding photochemical stability even after four runs in the photocatalytic test. A simple method for the synthesis of high performance co-sensitized TiO2 nanotube photocatalysts for application in solar energy conversion has thus been proposed in this work. The advantages of these new photoanodes for practical applications are low cost, ease of synthesis, high activity in visible light and excellent stability.

Preparation and gas-sensing performances of ZnO/CuO rough nanotubular arrays for low-working temperature H2S detection

Abstract: Nanotubular arrays composed of ZnO and CuO were prepared by ultrasonic spray pyrolysis (USP) and chemical bath deposition (CBD), consisting of internal hexagonal ZnO and external monoclinic CuO shell. Inside-out Ostwald ripening is proposed to explain the formation mechanism of the ZnO/CuO nanotubular arrays. The sensors based on ZnO/CuO nanostructure were fabricated and investigated the H 2 S-sensing properties. The results indicated that the sensor fabricated by ZnO/CuO nanotubes showed enhanced gas sensing properties compared to sensors based on pure ZnO nanorods and ZnO/CuO nanorods. These tube-like architectures could facilitate the diffusion and adsorption of the gas molecules, which could provide plenty of active sites between H 2 S gases and adsorbed oxygen. Therefore, an enhanced gas response, the relatively lower working temperature and shorter response time process could be achieved using ZnO/CuO tube-like architecture.

Solution-Processed Cu2S Photocathodes for Photoelectrochemical Water Splitting

Abstract: Cu2S has been regarded as a promising solar energy conversion material because of its favorable visible light absorption and earth abundance. Here, we present an indirect preparation method via a solution-processed ion exchange reaction to synthesize stoichiometric Cu2S films with high photoactivity. In addition, we developed a chemical bath deposition method to fabricate CdS buffer layers on Cu2S by adding a reducing agent in the precursor solution, avoiding oxidation of Cu2S. After being coated with the TiO2 protection layer and the RuOx hydrogen evolution catalyst, the Cu2S photoelectrode delivers a photocurrent density of 7.0 mA cm–2 at −0.3 V vs RHE and an onset potential of 0.48 V vs RHE under AM 1.5G simulated sunlight illumination for solar driven water reduction. To our knowledge, this is the first time that Cu2S has been used for solar hydrogen evolution with encouraging performance, which will stimulate further studies on Cu-based photocathodes.

Efficient Solar Cells Based on Light-Harvesting Antimony Sulfoiodide

Abstract: Although antimony sulfoiodide (SbSI) exhibits very interesting properties including high photoconductivity, ferroelectricity, and piezoelectricity, it is not applied to solar cells. Meanwhile, SbSI is predominantly prepared as a powder using a high-temperature, high-pressure system. Herein, the fabrication of solar cells utilizing SbSI as light harvesters is reported for the first time to the best of knowledge. SbSI is prepared by solution processing, followed by annealing under mild temperature conditions by a reaction between antimony trisulfide, which is deposited by chemical bath deposition on a mesoporous TiO2 electrode and antimony triiodide, under air at a low temperature (90 °C) without any external pressure. The solar cells fabricated using SbSI exhibit a power conversion efficiency of 3.05% under standard illumination conditions of 100 mW cm−2.

Nanostructure CdS/ZnO heterojunction configuration for photocatalytic degradation of Methylene blue

Abstract: In the present manuscript, thin films of Zinc Oxide (ZnO) have been deposited on a FTO substrate using a simple successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) method. Cadmium Sulphide (CdS) nanoparticles are sensitized over ZnO thin films using SILAR method. The synthesized nanostructured CdS/ZnO heterojunction thin films was characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), UV–Vis spectroscopy and Raman spectroscopy techniques. The band gap of CdS nanoparticles over ZnO nanostructure was found to be about 3.20 eV. The photocatalytic activities of the deposited CdS/ZnO thin films were evaluated by the degradation of methylene blue (MB) in an aqueous solution under sun light irradiation.

Deposition of Zinc Oxide on Different Polymer Textiles and Their Antibacterial Properties.

Abstract: A surface modification of polyamide 6 (PA), polyethylene terephthalate (PET) and polypropylene (PP) textiles was performed using zinc oxide to obtain antibacterial layer. ZnO microrods were synthesized on ZnO nanoparticles (NPs) as a nucleus centers by chemical bath deposition (CBD) process. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) indicated that wurzite ZnO microrods were obtained on every sample. Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM) and Liquid Absorption Capacity (LAC) analysis indicate that the amount and structure of antibacterial layer is dependent on roughness and wettability of textile surface. The rougher and more hydrophilic is the material, the more ZnO were deposited. All studied textiles show significant bactericidal activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). A possible mechanism and difference in sensitivity between Gram-negative and Gram-positive bacteria to ZnO is discussed. Considering that antibacterial activity of ZnO is caused by Reactive Oxygen Species (ROS) generation, an influence of surface to volume ratio and crystalline parameters is also discussed.

Solution-Processed Transparent Self-Powered p-CuS-ZnS/n-ZnO UV Photodiode

Abstract: Transparent diodes formed by a heterojunction between p-type CuS–ZnS and n-type ZnO thin films were fabricated by sequential chemical bath deposition and sol-gel spin coating. The diodes are transparent in the visible (≈70% at 550 nm) and exhibit a good rectifying characteristics, with If/Ir ratios of up to 800 at ±1 V, higher than most of the reported solution-processed diodes measured at a similar bias. More importantly, when operated as a self-powered (zero bias) UV photodetector, they show stable and fast (<1 s) photoresponse with a maximum responsivity of 12 mA W−1 at 300 nm. Both the response time and responsivity of the p-CuZnS/n-ZnO UV photodiode are comparable or superior to similar solution-processed devices reported in the literature.

Linear and Nonlinear Optics of CBD Grown Nanocrystalline F Doped CdS Thin Films for Optoelectronic Applications: An Effect of Thickness

Abstract: Fluorine (F) doped (i.e. 1 wt.%) cadmium sulfide (CdS) thin films with different thicknesses were fabricated on fluorine doped tin oxide coated glass substrates by chemical bath deposition methods. For doping of F, 1 wt.% ammonium fluoride was added into the solution. A significant influence of thicknesses on physical properties of F doped CdS thin films was observed. The thin films were investigated by various characterization techniques such as x-ray diffraction (XRD), UV–Vis–NIR, FT-Raman spectroscopy and scanning electron microscope. XRD analysis showed that the films are preferentially grown along (111) plane. The crystallites’ size changed with increases the film’s thickness. Films showed high transmittance in visible region. Raman spectra showed shift in first and second longitudinal phonon vibration (1LO and 2LO) with the change in thickness of the films. This shows that changing thickness leads to changes in the physical properties of films. The values of the band gaps were estimated as 2.60 eV, 2.75 eV, 2.80 eV for films of thickness 100 nm, 150 nm and 200 nm, respectively. Hence, the band gap of films increases with an increase in thickness. Refractive index, linear optical susceptibility, nonlinear optical susceptibility and nonlinear refractive index were also estimated. The higher values of nonlinear optical parameters shows good scope in nonlinear optical applications.

Cobalt sulfide thin films for electrocatalytic oxygen evolution reaction and supercapacitor applications.

Abstract: Nanocrystalline cobalt sulfide thin film electrodes have been deposited on stainless steel substrate using binder-free chemical bath deposition (CBD) method and electrochemical study is performed in 1 M KOH electrolyte. Linear sweep voltammetry (LSV) curve shows that cobalt sulfide thin film electrode requires 300 mV overpotential (ƞ) to reach the current density of 10 mA cm−2. Also, it exhibits Tafel slope of 57 mV decade−1 with stable catalytic activity over 14 h. Along with good electrocatalytic oxygen evolution performance, in supercapacitive study it shows specific capacitance of 252.39 F g−1 at a scan rate of 5 mV s−1. The stability test indicates that cobalt sulfide electrode is stable for 1000 cyclic voltammetry (CV) cycles.

Effect of Time on a Hierarchical Corn Skeleton-Like Composite of CoO@ZnO as Capacitive Electrode Material for High Specific Performance Supercapacitors

Abstract: CoO–ZnO-based composites have attracted considerable attention for the development of energy storage devices because of their multifunctional characterization and ease of integration with existing components. This paper reports the synthesis of CoO@ZnO (CZ) nanostructures on Ni foam by the chemical bath deposition (CBD) method for facile and eco-friendly supercapacitor applications. The formation of a CoO@ZnO electrode functioned with cobalt, zinc, nickel and oxygen groups was confirmed by X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), low and high-resolution scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis. The as-synthesized hierarchical nanocorn skeleton-like structure of a CoO@ZnO-3h (CZ3h) electrode delivered a higher specific capacitance (Cs) of 1136 F/g at 3 A/g with outstanding cycling performance, showing 98.3% capacitance retention over 3000 cycles in an aqueous 2 M KOH electrolyte solution. This retention was significantly better than that of other prepared electrodes, such as CoO, ZnO, CoO@ZnO-1h (CZ1h), and CoO@ZnO-7h (CZ7h) (274 F/g, 383 F/g, 240 F/g and 537 F/g). This outstanding performance was attributed to the excellent surface morphology of CZ3h, which is responsible for the rapid electron/ion transfer between the electrolyte and the electrode surface area. The enhanced features of the CZ3h electrode highlight potential applications in high performance supercapacitors, solar cells, photocatalysis, and electrocatalysis.