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Amorphous silicon
About: Amorphous silicon is a research topic. Over the lifetime, 26777 publications have been published within this topic receiving 423234 citations.
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TL;DR: By combining this state-of-the-art photoanode with an earth-abundant cobalt phosphate water-oxidation catalyst and a double- or single-junction amorphous Si solar cell in a tandem configuration, stable short-circuit water-splitting photocurrents of ~4 and 3 mA cm(-2) are achieved under 1 sun illumination.
Abstract: The photoactivity of metal oxide electrodes for water splitting is often limited by poor charge separation. Abdi et al. improve the solar-to-hydrogen efficiency in a hybrid device that comprises a gradient-doped bismuth vanadate photoanode and a double-junction amorphous silicon tandem solar cell.
1,126 citations
TL;DR: In this paper, a method was described in which crystalline silicon can be used as a practical anode material for lithium-ion batteries, and a cycling method was demonstrated in which the silicon is first partially converted to amorphous silicon, in situ, during conditioning cycles.
Abstract: A method is described in which crystalline silicon can be used as a practical anode material for lithium-ion batteries. Commercial lithium-ion cells are typically charged at a constant current to a fixed voltage and then are held by the charger at constant voltage until the current decreases to a certain value (also known as constant current/constant voltage or CCCV charging). It is first shown that CCCV charging can be used to reversibly cycle crystalline silicon and limit its capacity. A cycling method is then demonstrated in which crystalline silicon is first partially converted to amorphous silicon, in situ, during conditioning cycles. After the conditioning cycles the silicon can be cycled normally, using CCCV cycling limits, with good coulombic efficiency and little overlithiation during the first cycle.
1,049 citations
TL;DR: In this paper, the optical reflectance of the silicon nanowire solar cells is reduced by one to two orders of magnitude compared to planar cells, and a promising current density of ∼1.6mA∕cm2 for 1.8cm2 cells was obtained, with a broad external quantum efficiency of ∼12% at 690nm.
Abstract: Silicon nanowire-based solar cells on metal foil are described. The key benefits of such devices are discussed, followed by optical reflectance, current-voltage, and external quantum efficiency data for a cell design employing a thin amorphous silicon layer deposited on the nanowire array to form the p-n junction. A promising current density of ∼1.6mA∕cm2 for 1.8cm2 cells was obtained, and a broad external quantum efficiency was measured with a maximum value of ∼12% at 690nm. The optical reflectance of the silicon nanowire solar cells is reduced by one to two orders of magnitude compared to planar cells.
997 citations
TL;DR: In this article, an in situ X-ray diffraction study of the reaction of lithium with a-Si has been performed, and the results confirm that a new crystalline Li 15 Si 4 phase is formed below 30 mV as Li/Li + as first reported by Obrovac and Christensen in an article published in Electrochemical and Solid-State Letters.
Abstract: Silicon is a very promising candidate to replace graphite as the anode in Li-ion batteries because of its very high theoretical capacity. It has not yet made its way into commercial cells because of severe problems with the charge and discharge cycling of the material. It seems that amorphous silicon and amorphous silicon-containing alloys exhibit much improved cycling performance. Therefore, it is desirable to fully understand the reaction of Li with a-Si. To this end, an in situ X-ray diffraction study of the reaction of lithium with a-Si has been performed. The results confirm that a new crystalline Li 15 Si 4 phase is formed below 30 mV as Li/Li + as first reported by Obrovac and Christensen in an article published in Electrochemical and Solid-State Letters. However, the crystalline phase only forms for films of a-Si above a critical thickness of about 2 μm.
991 citations
PARC1
TL;DR: In this article, the authors investigated the influence of the Staebler-Wronski effect on undoped hydrogenated amorphous silicon with electron spin resonance and photoconductivity measurements.
Abstract: We study the magnitude of metastable light-induced changes in undoped hydrogenated amorphous silicon (the Staebler-Wronski effect) with electron-spin-resonance and photoconductivity measurements. The influence of the following parameters is investigated in a systematic way: sample thickness, impurity content, illumination time, light intensity, photon energy, and illumination and annealing temperatures. The experimental results can be explained quantitatively by a model based on the nonradiative recombination of photoexcited carriers as the defect-creating step. In the framework of this model, the Staebler-Wronski effect is an intrinsic, self-limiting bulk process, characterized by a strongly sublinear dependence on the total light exposure of a sample. The experimental results suggest that the metastable changes are caused by recombination-induced breaking of weak Si--Si bonds, rather than by trapping of excess carriers in already existing defects. Hydrogen could be involved in the microscopic mechanism as a stabilizing element. The main metastable defect created by prolonged illumination is the silicon dangling bond. An analysis of the annealing behavior shows that a broad distribution of metastable dangling bonds exists, characterized by a variation of the energy barrier separating the metastable state from the stable ground state between 0.9 and 1.3 eV.
990 citations