Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

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

The increasing energy demand in the near future will force us to seek environmentally clean alternative energy resources. The emergence of nanomaterials as the new building blocks to construct light energy harvesting assemblies has opened up new ways to utilize renewable energy sources. This article discusses three major ways to utilize nanostructures for the design of solar energy conversion devices:  (i) Mimicking photosynthesis with donor−acceptor molecular assemblies or clusters, (ii) semiconductor assisted photocatalysis to produce fuels such as hydrogen, and (iii) nanostructure semiconductor based solar cells. This account further highlights some of the recent developments in these areas and points out the factors that limit the efficiency optimization. Strategies to employ ordered assemblies of semiconductor and metal nanoparticles, inorganic-organic hybrid assemblies, and carbon nanostructures in the energy conversion schemes are also discussed. Directing the future research efforts toward utiliza...

Meeting the Clean Energy Demand: Nanostructure Architectures for Solar Energy Conversion

https://chemistry.beloit.edu/classes/nanotech/ZnO/mattoday10_05_40.pdf

ZnO - nanostructures, defects, and devices

A surface science perspective on TiO2 photocatalysis

Dye-sensitized photoelectrochem. solar cells constitute a promising candidate in the search for cost-effective and environment-friendly solar cells. The most extensively studied, and to date the most efficient systems are based on titanium dioxide. In this paper, the possibilities to use nanostructured ZnO electrodes in photoelectrochem. solar cells are investigated. Various exptl. techniques (e.g. IR, photoelectron, femtosecond and nanosecond laser spectroscopies, laser flash induced photocurrent transient measurements, two- and three-electrode photoelectrochem. measurements) show that the thermodn., kinetics and charge transport properties are comparable for ZnO and TiO2. The prepn. techniques of ZnO provide more possibilities of varying the particle size and shape compared to TiO2. However, the dye-sensitization process is more complex in case of ZnO and care needs to be taken to achieve an optimal performance of the solar cell.

Nanostructured ZnO electrodes for dye-sensitized solar cell applications

The dynamics of electron-transfer processes between bis(tetrabutylammonium) cis-bis(thiocyanato)bis(2,2'-bypiridine-4,4'-dicarboxylato)ruthenium(II) (called N719) and nanostructured ZnO films have ...

Electron injection and recombination in Ru(dcbpy)2(NCS)2 sensitized nanostructured ZnO

The anchoring of the ruthenium dye {(C4H9)4N}[Ru(Htcterpy)(NCS)3] (with tcterpy = 4,4‘,4‘ ‘-tricarboxy-2,2‘:6‘,2‘ ‘-terpyridine), the so-called black dye, onto nanocrystalline TiO2 films has been characterized by UV−vis and FT-IR spectroscopies FT-IR spectroscopy data suggest that dye molecules are bound to the surface by a bidentate binuclear coordination mode The interfacial electron-transfer (ET) dynamics has been investigated by femtosecond pump−probe transient absorption spectroscopy and nanosecond laser flash photolysis The electron-injection process from the dye excited state into the TiO2 conduction band is biexponential with a fast component (200 ± 50 fs) and a slow component (20 ps) These two components can be attributed to the electron injection from the initially formed and the relaxed dye excited states, respectively Nanosecond kinetic data suggest the existence of two distinguishable regimes (I and II) for the rates of reactions between injected electrons and oxidized dye molecules or o

Interfacial Electron-Transfer Dynamics in Ru(tcterpy)(NCS)3-Sensitized TiO2 Nanocrystalline Solar Cells

Ultrafast relaxation dynamics of charge carriers relaxation in ZnO nanocrystalline thin films

By using two-color femtosecond transient absorption spectroscopy, we have measured the electron injection rate for bis(tetrabutylammonium) cis di(thiocyanato) bis (2,2'-bypiridine-4,4' carboxylic acid)Ruthenium (II) dye (called N719) into SnO2 nanocrystalline thin films. The electron injection rate has been measured by monitoring the formation of the dye oxidized state and the arrival of electrons in the conduction band. Dynamics of electron injection are multiexponential (0.2, 4 and 130 ps) and are therefore slower than the N719-ZnO or N719-TiO2 systems. The photocurrent action spectrum of N719-SnO2 shows a quantum efficiency of 0.65 at 530 nm proving that efficient charge separation can take place despite of the relatively slow electron injection rate.

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Christophe Bauer

Papers

Nanostructured ZnO electrodes for dye-sensitized solar cell applications

Electron injection and recombination in Ru(dcbpy)2(NCS)2 sensitized nanostructured ZnO

Interfacial Electron-Transfer Dynamics in Ru(tcterpy)(NCS)3-Sensitized TiO2 Nanocrystalline Solar Cells

Ultrafast relaxation dynamics of charge carriers relaxation in ZnO nanocrystalline thin films

Ultrafast studies of electron injection in Ru dye sensitized SnO2 nanocrystalline thin film