Search

We conducted a chronoamperometric study to observe the electrochemical behaviors of the nucleation mechanism of electrodeposited Cu(In,Al)Se 2 films. A change from instantaneous nucleation to progressive nucleation was observed by increasing the copper concentration. SEM and EDS analyses demonstrated that the surface morphologies and chemical compositions of precursor and post-annealed Cu(In,Al)Se 2 films were influenced by the nucleation mechanism. They exhibited that Cu(In,Al)Se 2 films had roughly cauliflower-like and triangular structures with Cu-poor composition at the instantaneous nucleation mechanism, whereas smooth and round structures with Cu-rich composition at the progressive nucleation mechanism. Additionally, the quality, growth orientation, composition phase, and optical energy band gap of Cu(In,Al)Se 2 films were examined using X-ray diffraction (XRD) patterns, Raman spectra, and ( αhν ) 2 vs. hν plots (UV–vis). Thereafter, the performances of rudimentary Cu(In,Al)Se 2 solar cells fabricated at various copper concentrations were discussed, the conversion efficiency of electrodeposited Cu(In,Al)Se 2 solar cells were unpublished in previous literatures. Our studies demonstrated that the performances of Cu(In,Al)Se 2 solar cells were significantly related to the surface morphology and composition of Cu(In,Al)Se 2 absorber layer. The highest conversion efficiency of Cu(In,Al)Se 2 solar cells fabricated at a 2-mM copper concentration was 1.96% with open-circuit voltage, short-circuit current, fill factor, R sh and R s values of 0.189 V, 29.21 mA/cm 2 , 35.4%, 125 Ω and 2.82 Ω, respectively. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the cyclic voltammetric studies were used to realize the element's reduction potential and chemical reaction mechanism for presuming the formation routes of quaternary Cu(In,Al)Se2 crystals. Thereafter, the prior adjustment of deposited potential from −0.6V to −1.0V can be identified a suitable potential as co-electrodeposition. The material characteristics of Cu(In,Al)Se2 films are dominated by the percentage of aluminum content. Thus, the influence of aluminum and indium concentrations in solutions on the percentage composition, surface morphology, structural and crystal properties, and optical energy band gap of Cu(In,Al)Se2 films were investigated. Energy dispersive X-ray spectroscopy (EDS) indicated that the ratio of Al to (Al+In) in Cu(In,Al)Se2 films varied from 0.21 to 0.42 when adjusting aluminum and indium concentrations in solutions. Scanning electron microscopy (SEM) shows that the surface morphology changed from round-like structures into cauliflower-like structures and became rough when the aluminum concentration increased and indium concentration decreased in solutions. X-ray diffraction (XRD) patterns revealed three preferred growth orientations along the (112), (204/220), and (116/312) planes for all species. The (αhυ)2 versus hυ plots (UV–Visible) shows that the optical energy band gap of the Cu(In,Al)Se2 films can be successfully controlled from 1.17eV to 1.48eV by adjusting the aluminum and indium concentrations. Furthermore, the shift of the (112) peak in the XRD patterns and variation of optical band gap are evidence that the incorporation of aluminum atoms into the crystallitic CuInSe2 forms Cu(In,Al)Se2 crystals. [Copyright &y& Elsevier]

Abstract: The study addresses the optical properties and morphologies of Al-doped ZnO (AZO) films textured by the chemical wet-etching method using three different acid solutions: HCl, HNO3, and H3PO4. An initial AZO film was sputtered on a glass substrate by rf magnetron sputtering. The film surface was then textured by wet-etching using diluted HCl, HNO3, or H3PO4. The average transmittance of all the post-treated ZnO:Al films remains around 75–80% as measured by a UV–vis analyzer. A haze ratio calculation shows that the light scattering properties can be significantly controlled by varying the etchant species, acid concentration, and etching time. Further, the HNO3 etchant gives the highest haze ratio of 43.0% at a wavelength of 550nm. Compared with solar cells deposited on non-textured ZnO:Al films, a significant enhancement in the short-circuit current density of 17.8% for the a-Si solar cells with textured ZnO:Al films was achieved. [Copyright &y& Elsevier]

Abstract Cloud computing and services have greatly changed the way how people develop and use software, and also raised a lot of new research issues. In this paper, we investigate two such important issues, service deployment and service request scheduling, for composite cloud services in dynamic cloud environments. We present load-aware service deployment approaches for dynamic workload and a service request scheduling method based on task ranking mechanisms. The proposed approaches can effectively improve the execution performance of composite cloud services in dynamic cloud environments. A series of simulation experiments have been conducted to evaluate the proposed approaches. The experimental results show that our approaches outperform previous methods significantly in terms of average service response time. [ABSTRACT FROM AUTHOR]