Papers by Keyword: Chemical Bath Deposition (CBD)

Abstract: In this paper, we mainly talk about two kinds of ZnO nanostructure materials which are rod and flower structure by hydrothermal growth as photoanode of quantum dot sensitized solar cells (QDSSCs). Using chemical bath deposition to assemble CdS quantum dots onto ZnO nanostructure materials, and after different CBD cycles we could get the cell parameters of different CBD cycles respectively in their I-V curves, from which we could see it is the flower structure that has the highest efficiency which is 0.346% after 9 CBD cycles and the short-circuit current is 2.88 mA/cm². Therefore, we could see that ZnO flower structure has a potential application in solar cell devices as the photoelectrode to gain higher photoelectric conversion efficiency (PCE).

Abstract: Thin film deposition of PbS is conveniently carried out by chemical reactions of lead acetate with thiourea at room temperature. Energy dispersive analysis of X-ray (EDAX), X-ray diffraction (XRD), selected area electron diffraction patterns (SAED), UV-Vis-NIR spectrophotometer, Scanning Electron Microscopy (SEM), Atomic force microscopy (AFM), Photoluminescence (PL) and Raman spectroscopy techniques are used for characterizing thin films. EDAX spectra shows that no impurity is present and XRD pattern indicates face centered cubic structure of PbS thin films. The average crystallite size obtained using XRD is about 15nm calculated using Scherrer’s formula and that determined from Hall-Williamson plot was found to be 18nm. SAED patterns indicate that the deposited PbS thin films are polycrystalline in nature. Blue shift due to quantum confinement was seen from the UV-Vis-NIR absorption spectra of thin film in comparison with bulk PbS. The Photoluminescence spectra obtained for thin film with different excitation sources shows sharp emission peaks at 395nm and its intensity of photoluminescence increases with increasing the excitation wavelength. Raman spectroscopy of deposited thin film was used to study the optical phonon modes at an excitation wavelength of 488nm using (Ar+) laser beam.

Abstract: SnS thin film has been deposited on glass substrate at room temperature using low cost, environmental friendly chemical bath deposition (CBD) technique. The structural parameters of the deposited film have been investigated through X- ray diffraction measurements. The deposited SnS film found almost crystalline with preferred orientations along (111) planes revealing an orthorhombic phase of herzenbergite SnS structure. The lattice parameters and dislocation density were determined. The average grain size estimated to be ~ 25 nm. The surface morphology of the film examined using scanning electron microscopy (SEM) show uniform granular and any crack or pinhole free deposition of the film. The chemical compositions of the film examined using energy dispersive analysis of x-rays (EDAX) confirmed stoichiometric deposition. The analysis of the optical absorption spectra of the deposited film in the wavelength range of 200-1200 nm indicate that direct allowed transitions are dominant in the film. The direct band gap of the film determined to be ~ 1.92 eV which is higher than those reported earlier for bulk or single crystal SnS, exhibiting quantum size effect at the observed grain size in the film. This value of band gap is promising for possible use of the deposited film as absorption layer in photovoltaic structures like solar cells. The thermoelectric power measurements indicate p-type electrical conductivity of the deposited films. A systematic study on room temperature chemical deposition and characterization of SnS thin films suitable for absorber layer in photovoltaic structures has been reported.

Abstract: A Lead sulfide (PbS) film synthesized by ultrasonic wave assisted chemical bath deposition (CBD) method. The as-deposited films were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) measurements. The photoelectrochemical (PEC) cell, with PbS/ITO/glass as a photo cathode and Na₂SO₄ (0.10 M) solution as an electrolyte, was constructed and investigated for PEC properties. The film shows a p-type conduction mechanism.

Abstract: Cd_1-xCo_xS (0 x 0.5) thin films have been deposited by liquid phase chemical bath deposition method on glass substrate from a complex liquid phase formed by equimolar volumes of cadmium sulphate, thiourea and cobalt sulphate. For deposition various preparative parameters, such as speed, temperature, pH, and time were optimized and found to be 70 ± 2 rpm, 56 ^°C, 11±0.2 and 80 min. respectively. The samples were thin, uniform and tightly adherent with colour changing from orange red to dark chocolate as x was varied from 0 to 0.5. The films were characterized to evaluate the surface morphology, composition and optical measurements. The surface morphologies of these films revealed random orientation of the crystallites of elongated rhomboids with sharp and clear edges having leaf like appearance. The grain size is found to be enhanced continuously from x = 0 to x = 0.1 with fine and more clear grain boundaries and decreased for higher x values. Energy Dispersive X-ray analysis suggests that the deposits are Cd rich. The optical studies were performed on these samples in the range of wavelengths between 500 nm to 1300 nm and yield a high absorption coefficient (α 10⁴-10⁵ cm^-1) with a direct type of transitions. The estimated band gap decreased from 2.42 eV to 1.94 eV as x was varied from 0 to 0.5.

Abstract: This report describes the preparation of gas sensors based on SnO₂ semiconductor nanostructure thin films synthesized using chemical bath deposition (CBD) technique. As the rapid demand of the gas sensors based on the semiconductor materials, there have been significant efforts to improve the performance of the semiconductors sensors. SnO₂, which has good electrical and mechanical properties, is one of the potential materials to be developed. In the present study, the SnO₂, prepared using CBD technique with stannous cloride as precursors, has nanopattern that give much SO₂ particles to access into the semiconductor surface. The resulting nanostructure SnO₂ thin films have been confirmed by X Ray Diffractions (XRD), Energy Dispersive Spectroscopy (EDS) and Scanning Electronic Micrsocopy (SEM). The as fabricated SnO₂ thin films sensors were then characterized as SO₂ gas sensors in various concentrations for several different operating temperatures. The sensors have good sensitivity as low as 30 ppm of SO₂ gas at the optimum temperature of 200⁰ C.

Abstract: In the present work, ZnO nanorods array were successfully grown on ITO substrate via chemical bath deposition method (CBD). The seeding solution was prepared at low temperature (0°C) using zinc nitrate tetrahydrate and hexamethylenetetramine. The as-deposited ZnO nanorods were hexagonal wurtzite structure growing vertically on the substrate. Various reaction times from 3 to 5 hours were applied upon the CBD process at 90°C. The results showed that the duration of reaction time has affected the nanorods array properties. With the increase of reaction time from 3 to 5 hours has increased the diameter and crystallite size of nanorods from 325 to 583 nm, and from 22.68 to 34.28 nm. As a result, the band gap energy, E_g of ZnO nanorods decreased from 3.63 to 3.13 eV.

Abstract: Zinc oxide (ZnO) is an inorganic semiconductor material which has been widely studied due to its various potential applications. Over the past decades, one-dimensional (1-D) nanostructures such as nanowires and nanorods have stimulated significant scientific interests because of their unique properties in comparison to bulk materials. For the application of dye sensitized solar cell (DSSC), 1-D ZnO nanostructures are more desired than the spherical nanoparticles since the former provides ballistic effect leading to faster electron transfer which in turn can increase the device performance. Motivated by this consideration, in the current study ZnO nanorods were deposited on ITO glass substrate via chemical bath deposition (CBD) process where the seeding solution was prepared at 0°C. In order to increase their crystallinity and optical properties, the as-deposited ZnO nanorods were subjected to post-hydrothermal treatment at 150°C for 3, 6 and 9 hours. The scanning electron microscope (SEM) analysis revealed that the ZnO nanorods were successfully grown as vertically-aligned hexagonal structure, while the X-ray diffraction (XRD) study showed that the intensity of (002) crystal plane is the highest peak for all nanorod samples. The optical study by UV-Vis spectroscopy showed that the absorption edge of the as-deposited sample was slightly red-shifted to visible region after post-hydrothermal treatment. The ZnO nanorods sample derived from post-hydrothermal treatment for 6 hours provided the optimum nanostructural characteristics with an average diameter of 228 nm, crystallite size of 27.97 nm and the band gap energy, E_g, of 3.12 eV.

Abstract: ZnO nanorod arrays were successfully prepared by chemical bath deposition (CBD) and hydrothermal method (HTM), respectively. The photovoltaic performance of ZnO nanoarrays as photoelectrodes in dye-sensitized solar cells (DSCs) was investigated. Experimental results show that ZnO seed crystals prepared by a sol-gol process have c axis orientation and consist of nanoparticles within the range of 50~100nm. The same particle size and orientation is well preserved in ZnO nanoarrays grown on the seed crystal layers. The photovoltaic performance of DSCs based on ZnO nanoarrays as the photoelectrodes is poor, due to the weaker adsorption bond force between ZnO and dye, and lower dye adsorption quantity. By contrast, the DSCs composed of ZnO arrays prepared by hydrothermal method have optimal performance, the corresponding short circuit photocurrent density (J_sc), open circuit voltage (V_oc), fill factor (FF) and photoelectric conversion efficiency (η) are 4.89 mA/cm², 0.650V, 0.39 and 1.25 %, respectively.

Abstract: Using chemical bath deposition (CBD) deposited CdS thin films for two times and prepared CdS films contained different thickness Dy-doping layer by connecting using the vacuum electron beam evaporation method, then studied the structure, surface morphology, optical and electrical properties of the films. The results show that no-doped CdS films are the cubic structure and preferentially oriented in the (111) directions. Its conductive type is N type. After Dy doping the CdS thin films are mixed structure by cubic and hexagonal phase, the conductive type is still N type, the uniformity and compactness of the films are improved. At the same time, the proportion of Cd and S atoms in Dy-doping films are more close to the stoichiometric ratio. Dy-doping can also reduce the resistivity of the films, result in an increase of carrier concentration and improve the transmittance in the visible region.