A high light scattering morphology on glass used as a substrate for thin film solar cells was fabricated using spherical silica particles and spin-on-glass. After deposition of Al-doped ZnO thin films, a hemispherical morphology appeared at the surface, and a high haze value of 77% ( = 900 nm) was obtained when the cover ratio of the silica particle was 44%. The quantum efficiency of microcrystalline thin film Si solar cells was improved at wavelengths over 700 nm due to the textured morphology formed by the silica particles and spin-on-glass. Keywords: transparent conductive oxide, light scattering, silica particle, spin-on-glass, solar cell Thin film Si solar cells based on hydrogenated amorphous Si and hydrogenated microcrystalline Si have been considered to have a reduced manufacturing cost compared with crystal type Si solar cells due to their reduced use of Si materials. However, the conversion efficiency of thin film Si solar cells is much lower than that of crystal Si solar cells owing to their lower photo absorption in the near infrared region which can be attributed to their indirect-transition type absorption and thin Si layer thickness. In order to increase in the conversion efficiency of thin film Si solar cells, improvement in the optical path length in the near infrared region is necessary. In order to confine the light and thereby increase the optical path length within the solar cells, a textured morphology has been formed on a transparent conductive oxide (TCO) substrate.13) Such a textured morphology induces scattering and the confinement of the incident light within the solar cells. Consequently, the optical path length and total amount of optical absorption in the thin film Si solar cell are increased significantly. Many types of textured morphologies prepared by various methods have been proposed, 48) the light scattering characteristics of which are determined by their textured width and height.
9)Hongsingthong et al. reported that a cauliflower-like textured TCO substrate with different sized texturing formed on textured glass etched by a reactive ion etching method achieved high light scattering characteristics in the visible and near infrared region.10) The formation of such a textured morphology on a glass surface is considered to be an effective method for improvement of the optical confinement properties of the solar cells. However, different-sized textured TCOs have not yet been commercialized due to the difficulties in their large-scale fabrication at sufficiently low cost. Plasma-etching techniques have been widely used as a candidate methodology for the formation of a textured morphology on a glass surface. However the production cost is too high for commercialization due to the high cost of the required vacuum equipment. Therefore, an alternative methodology yielding a low cost texturing process which could be applied to large scale substrates is required. In this study, we demonstrate the fabrication of a textured TCO substrate with high light scattering characteristics with a ...
SUMMARY:About seventy strains of strict anaerobes (Peptococcus, Peptostreptococcus, Bacteroides, Sphaerophorus, Fusobacterium, anaerobic Corynebacterium and Eubacterium) were found to grow relatively well on Phenylethyl Alcohol (PEA) agar containing 5 % pepsin-digested cattle blood. However, half of strains of Veillonella and two-thirds of strains of Clostridium showed no or poor growth.Mixed cultures of aerobes and anaerobes were inoculated onto PEA agar to find how effective this medium was in selective isolation of anaerobes. A few clinical cases in which PEA agar was used are presented.The data presented in this paper confirmed and extended the results shown in a brief report of Dowell, Hill and Altemeier (1964) in which only a small number of anaerobes were examined.Their recommendation that PEA agar should be used routinely for isolation of anaerobes in clinical materials was approved. Some precautions in handling and the limitations of this medium are discussed.
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