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

High Aspect Ratio Fine Gridline for Front Side Metallization of Industrial Silicon Solar Cells by Direct Printing

Silicon solar cell efficiencies of 17.1%, 16.4%, 14.8%, and 14.9% have been achieved on FZ, Cz, multicrystalline (mc-Si), and dendritic web (DW) silicon, respectively, using simplified, cost-effective rapid thermal processing (RTP). These represent the highest reported efficiencies for solar cells processed with simultaneous front and back diffusion with no conventional high-temperature furnace steps. Appropriate diffusion temperature coupled with the added in-situ anneal resulted in suitable minority-carrier lifetime and diffusion profiles for high-efficiency cells. The cooling rate associated with the in-situ anneal can improve the lifetime and lower the reverse saturation current density (J/sub o/), however, this effect is material and base resistivity specific. PECVD antireflection (AR) coatings provided low reflectance and efficient front surface and bulk defect passivation. Conventional cells fabricated on FZ silicon by furnace diffusions and oxidations gave an efficiency of 18.8% due to greater short wavelength response and lower J/sub o/.

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Rapid thermal processing of high-efficiency silicon solar cells with controlled in-situ annealing

Optimization of front metal contact firing scheme to achieve high fill factors on screen printed silicon solar cells

Comparison of light-induced degradation and regeneration in P-type monocrystalline full aluminum back surface field and passivated emitter rear cells

This paper summarizes our progress in fabricating record-high efficiency ribbon Si solar cells with screen-printed and photolithography defined contacts. We have developed and optimized rapid thermal processing enhanced SiN/sub x/-induced hydrogenation to achieve record-high efficiency screen-printed EFG (15.9%) and String Ribbon (15.6%) cells and a high-efficiency string ribbon cell (17.8%) with photolithography defined contacts. A low-frequency SiN/sub x/ film and a two-step RTP firing process were critical in achieving high-efficiency screen-printed cells. Step 1 provides SiN/sub x/ induced hydrogenation and forms an aluminum doped back surface field. Step 2 is designed for Ag grid firing and includes rapid cooling to retain hydrogen introduced in Step 1.

Ajeet Rohatgi

Papers

High Aspect Ratio Fine Gridline for Front Side Metallization of Industrial Silicon Solar Cells by Direct Printing

Rapid thermal processing of high-efficiency silicon solar cells with controlled in-situ annealing

Optimization of front metal contact firing scheme to achieve high fill factors on screen printed silicon solar cells

Comparison of light-induced degradation and regeneration in P-type monocrystalline full aluminum back surface field and passivated emitter rear cells

Implementation of rapid thermal processing to achieve greater than 15% efficient screen-printed ribbon silicon solar cells