20 research outputs found

    Silicon solar cells for space use: Present performance and trends

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    A technology assessment of present performance levels and current fabrication methods and designs is presented

    Development of high efficiency (14 percent) solar cell array module

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    Most effort was concentrated on development of procedures to provide large area (3 in. diameter) high efficiency (16.5 percent AM1, 28 C) P+NN+ solar cells. Intensive tests with 3 in. slices gave consistently lower efficiency (13.5 percent). The problems were identified as incomplete formation of and optimum back surface field (BSF), and interaction of the BSF process and the shallow P+ junction. The problem was shown not to be caused by reduced quality of silicon near the edges of the larger slices

    Development of High Efficiency (14%) Solar Cell Array Module

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    High efficiency solar cells required for the low cost modules was developed. The production tooling for the manufacture of the cells and modules was designed. The tooling consisted of: (1) back contact soldering machine; (2) vacuum pickup; (3) antireflective coating tooling; and (4) test fixture

    Synthesis of copper-silver doped hydroxyapatite via ultrasonic coupled sol-gel techniques: structural and antibacterial studies

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    Fabrication of hydroxyapatite (HA) via doping with metal ions to enhance its antibacterial properties has attracted much interest. The present study aims to synthesize copper-silver doped hydroxyapatite particles (Cu-Ag doped HA) with an improved antibacterial activity through a sol-gel technique coupled with ultrasonic irradiation. The doping materials consist of Cu2+ and Ag+ ions with precursor molar ratios of 0.0, 0.25, 0.50, 0.75 and 1.0. The physicochemical properties of Ca9.0Cu1.0-xAgx(PO4)6(OH)2 samples were investigated using X-ray diffraction, Fourier-transform infrared spectroscopy (FT-IR), and transmission electron microscopy coupled with energy dispersive X-ray analysis (TEM-EDS). Characterization studies revealed that Cu2+ and Ag+ ions were incorporated into a hexagonal framework of HA. The main functional groups were identified as hydroxyl (OH−) and phosphate (PO43−) moieties. Their morphologies were rod-shaped with various diameters and particle size distributions, depending on the molar ratio of Cu2+ to Ag+. Antibacterial activity was evaluated using an agar well diffusion method against Staphylococcus epidermis, S. aureus, Bacillus subtilis, B. cereus, and Pseudomonas aeruginosa. It was found that Cu-Ag doped HA is an effective antibacterial agent. Ca9.0Cu0.5Ag0.5(PO4)6(OH)2 showed the best antibacterial performance against all bacterial strains with inhibition zones ranging from 13 to 17 mm, indicating its suitability as an antibacterial material in biomedical applications
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