Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

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Dye-Sensitized Solar Cells

Excitonic solar cells1—including organic, hybrid organic–inorganic and dye-sensitized cells (DSCs)—are promising devices for inexpensive, large-scale solar energy conversion. The DSC is currently the most efficient2 and stable3 excitonic photocell. Central to this device is a thick nanoparticle film that provides a large surface area for the adsorption of light-harvesting molecules. However, nanoparticle DSCs rely on trap-limited diffusion for electron transport, a slow mechanism that can limit device efficiency, especially at longer wavelengths. Here we introduce a version of the dye-sensitized cell in which the traditional nanoparticle film is replaced by a dense array of oriented, crystalline ZnO nanowires. The nanowire anode is synthesized by mild aqueous chemistry and features a surface area up to one-fifth as large as a nanoparticle cell. The direct electrical pathways provided by the nanowires ensure the rapid collection of carriers generated throughout the device, and a full Sun efficiency of 1.5% is demonstrated, limited primarily by the surface area of the nanowire array.

/pdf/nanowire-dye-sensitized-solar-cells-2cw2kqhfoz.pdf

Nanowire dye-sensitized solar cells

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

Transparent conductors as solar energy materials: A panoramic review

http://nathan.instras.com/documentDB/paper-12.pdf

Applications of functionalized transition metal complexes in photonic and optoelectronic devices

Photoelectrochemical properties of nanostructured ZnO thin film electrodes have been investigated in the UV and visible regions. For films consisting of 15 nm large undoped crystallites a maximum monochromatic current conversion efficiency of 58% was obtained in the visible using a ruthenium-based dye as a sensitizer. The overall solar energy conversion efficiency for this film was 2%. In comparison, sensitized films consisting of 150 nm large Al-doped crystallites yield a monochromatic current conversion efficiency of 31% and an overall solar energy conversion efficiency of 0.5%. The study also shows that nanostructured ZnO may give high efficiencies in the UV region, approaching unity for the Al-doped films.

High Light-to-Energy Conversion Efficiencies for Solar Cells Based on Nanostructured ZnO Electrodes

A chemical precipitation method has been used for the synthesis of ZnO nanoparticles with controlled morphology. The precursor powders were prepared using several precipitation reagents and using ammonium carbamate as a precipitating reagent led to unusual rod-shape morphology. The precursor was decomposed by heating in air resulting in the formation of spherical or rod-like shapes of zinc oxide. A flow injection synthesis technique has been developed to synthesize nanophase particles of zinc oxide. The precursor and decomposed products were analyzed using IR, SEM, XRD and TGA techniques. The average size of the particles of ZnO obtained using the flow injection technique was approximately 20 nm while the crystallite size as measured from the X-ray pattern was 10–15 nm.

Synthesis of zinc oxide nanoparticles with controlled morphology

Synthesis of superconducting Pb/Sb doped BiSrCaCuO compounds via oxalate coprecipatation

A controlled coprecipitation technique has been used to synthesize precursors of superconducting BiPbSrCaCuO ceramics. The oxalate precursors were nano-sized powders with high homogeneity, low crystallinity, and well-defined stoichiometry. These precursors have been used to fabricate superconducting tapes by the powder-in-tube technique, which involves the use of Ag sheaths. The nano-sized homogeneous powders require considerably reduced tape-processing (sintering) times for Bi-2223 formation, and provide 'clean' intergrain boundaries within the sintered tapes. As a result, high critical transport current density, Jc, can be obtained even in multiphase composites that do not necessarily exhibit a high degree of texture. To gain further insight into the role of microstructural details at each step of the tape fabrication, extensive X-ray diffraction analyses and scanning electron microscopy measurements have been made. The influence of homogeneity and grain size distribution on the superconducting properties of the Ag-clad tapes is discussed. We have reproducibly achieved, within 60 h of the thermal processing, Jc values as high as 4.4*104 A cm-2 at 77 K in zero applied magnetic field.

Nanophase precursors for high-Jc Ag-clad superconducting BiPbSrCaCuO tapes

Single phase YBa2Cu4O8 films were obtained by Nd:YAG pulsed laser deposition and subsequent annealing. STM / SEM characterization reveal that these films consist of strongly c-oriented nano-sized grains. The observed rather low critical current [ J c (5 K , H = 0) ≃ 1 s 10 3 A/cm 2 ] make these films promising for fast response low field sensor applications.

Lingna Wang

Papers

High Light-to-Energy Conversion Efficiencies for Solar Cells Based on Nanostructured ZnO Electrodes

Synthesis of zinc oxide nanoparticles with controlled morphology

Synthesis of superconducting Pb/Sb doped BiSrCaCuO compounds via oxalate coprecipatation

Nanophase precursors for high-Jc Ag-clad superconducting BiPbSrCaCuO tapes

Nanocrystalline YBa2Cu4O8 c-oriented films prepared by Nd:YAG laser deposition