Transparent conductors—A status review

Energy harvesting generators are attractive as inexhaustible replacements for batteries in low-power wireless electronic devices and have received increasing research interest in recent years. Ambient motion is one of the main sources of energy for harvesting, and a wide range of motion-powered energy harvesters have been proposed or demonstrated, particularly at the microscale. This paper reviews the principles and state-of-art in motion-driven miniature energy harvesters and discusses trends, suitable applications, and possible future developments.

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Energy Harvesting From Human and Machine Motion for Wireless Electronic Devices

This Review focuses on recent developments in the use of ZnO nanostructures for dye-sensitized solar cell (DSC) applications. It is shown that carefully designed and fabricated nanostructured ZnO films are advantageous for use as a DSC photoelectrode as they offer larger surface areas than bulk film material, direct electron pathways, or effective light-scattering centers, and, when combined with TiO2, produce a core–shell structure that reduces the combination rate. The limitations of ZnO-based DSCs are also discussed and several possible methods are proposed so as to expand the knowledge of ZnO to TiO2, motivating further improvement in the power-conversion efficiency of DSCs.

https://depts.washington.edu/solgel/documents/pub_docs/journal_docs/2009/advanced_material2009.pdf

ZnO Nanostructures for Dye-Sensitized Solar Cells

http://nathan.instras.com/documentDB/paper-44.pdf

Surface photovoltage phenomena: theory, experiment, and applications

To convert the energy of sunlight into chemical energy, the leaf splits water via the photosynthetic process to produce molecular oxygen and hydrogen, which is in a form of separated protons and electrons. The primary steps of natural photosynthesis involve the absorption of sunlight and its conversion into spatially separated electron–hole pairs. The holes of this wireless current are captured by the oxygen evolving complex (OEC) of photosystem II (PSII) to oxidize water to oxygen. The electrons and protons produced as a byproduct of the OEC reaction are captured by ferrodoxin of photosystem I. With the aid of ferrodoxin–NADP+ reductase, they are used to produce hydrogen in the form of NADPH. For a synthetic material to realize the solar energy conversion function of the leaf, the light-absorbing material must capture a solar photon to generate a wireless current that is harnessed by catalysts, which drive the four electron/hole fuel-forming water-splitting reaction under benign conditions and under 1 su...

The artificial leaf

Phosphorus and aluminum gettering conditions were optimized to achieve high-frequency polycrystalline silicon cells. In order to take advantage of intense gettering without the harmful effects of the emitter dead layer, a deep phosphorus diffusion at 930 degrees C was performed, followed by a partial etch-back of the n/sup +/ region. The optimum aluminum treatment for these cells included 1.2- mu m-thick Al deposition followed by 850 degrees C, 35-min drive-in. Oxide passivation was found to be effective in cells made on these polysilicon wafers. A combination of optimum phosphorus and aluminum getting, oxide passivation, and double-layer antireflection coating resulted in record 17.7% efficient, 1-cm/sup 2/, cells under one sun illumination. Cell model calculations were performed ignoring the grain boundary effects, but using a measured effective lifetime in the cell. A good correlation was found between measured and calculated cell parameters of the 17.7% efficient polycrystalline silicon cell. Model calculations were extended to outline an approach toward achieving greater than 20% efficient cells. >

Fabrication and analysis of high-efficiency polycrystalline silicon solar cells

A boron diffusion process using boric acid as a low cost, nontoxic spin-on source is introduced. Using dilute solutions of boric acid, sheet resistances ranging from 20 to 200 Ω/□ were achieved, along with saturation current densities as low as 85 fA/cm 2 . These results indicate that boric acid is a suitable source for forming both p + emitters and back surface fields for high efficiency n- and p-type solar cells. The degradation of the minority carrier bulk lifetime, which is a common efficiency-limiting characteristic of low cost boron sources, was also minimized through the use of a high purity boric acid source. The ability to achieve low sheet resistances, high bulk lifetimes and low saturation current densities with boric acid were exploited to achieve a 19.7% efficient screen printed solar cell exhibiting a bulk lifetime >400 μs.

http://jes.ecsdl.org/content/157/6/H684.full.pdf

Boron Diffusion with Boric Acid for High Efficiency Silicon Solar Cells

Etude de la duree de vie des porteurs minoritaires dans du silicium libre de dislocation, dope avec du gallium. Influence de la concentration en impurete, ainsi que des differents parametres de croissance cristalline

Some Effects of Crystal Growth Parameters on Minority Carrier Lifetime in Float‐Zoned Silicon

Fundamental understanding and implementation of Al-enhanced PECVD SiNx hydrogenation in silicon ribbons

The interaction of hydrogen, injected into silicon using low‐energy ion bombardment, with slow (Ti and V) and fast (Cr and Au) diffusing impurities was investigated. It was found that this H ion bombardment of the Si surface was effective in reducing the electrically active concentration of only the fast diffusing impurities. The results are explained by damage enhanced diffusivity and surface gettering of the fast diffusing impurities.

Ajeet Rohatgi

Papers

Fabrication and analysis of high-efficiency polycrystalline silicon solar cells

Boron Diffusion with Boric Acid for High Efficiency Silicon Solar Cells

Some Effects of Crystal Growth Parameters on Minority Carrier Lifetime in Float‐Zoned Silicon

Fundamental understanding and implementation of Al-enhanced PECVD SiNx hydrogenation in silicon ribbons

Interaction of low‐energy implanted atomic H with slow and fast diffusing metallic impurities in Si