Semiconductors nanocrystalline metal oxide

Metal oxides represent an important class of materials with a variety of technological applications. In general, transition metal oxides are vital for a series of technologies, such as solar cells and Li ion batteries. Several reports in the literature describe the effects of size on the various properties of this class of materials. Nanocrystalline metal oxide semiconductors such as Ti02, Sn02 and ZnO, for example, display... 

One successful application of a solar cell using metal oxide as an electron acceptor is the dye-sensitized solar cell (DSSC). In DSSCs, organic or metal complex dyes are usually chemically adsorbed on the surface of a wide band gap metal oxide semiconductor nanocrystalline electrode by an anchor group(s) (for example the carboxyl group). Nanocrystalline electrodes are made by sintering nanoparticles, so that a large surface area is obtained on the porous... 

There are some advantages of IR probe transient absorption for investigating dye-sensitized metal oxide semiconductors. Since the absorption of injected electrons does not usually overlap other absorption bands of the dye molecule, it is easy to analyze the electron injection process. It is easy to compare electron injection processes in different kinds of dye molecule, because the reaction product is always the same, the conductive electron, unless one changes the metal oxide nanocrystalline film. Then not only the reaction rates but also the reaction yields can be compared by measuring the absorption intensities in the timescale just after the reactions are completed. This information is important especially when discussing the relation between the electron injection process and solar cell performance such as the photocurrent generation yield. It is hard to evaluate and compare electron injection yields for... 

Electrodes can be prepared with films of semiconductor particles. A straightforward approach involves suitable chemical treatment of a substrate metal, e.g., chemical or anodic oxidation of Ti to form a film of Ti02, which is made up of many small crystals, called grains. An alternative is to spread a film of semiconductor particles on an electrode surface. Films of nm-size semiconductor particles nanocrystalline films) have been of special interest. Such small particles (variously called quantum particles, Q-particles, or quantum dots), have properties that differ from those of larger (/xm) dimension (86, 87). 

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