Interface light-absorbing sensitizer

Figure 1. A photoelectrochemlcal cell with a polymer/electrolyte interface containing a light absorbing sensitizer (S) embedded in the polymer. Light absorption may enable a redox reaction of (R) dissolved in the electrolyte. When a semiconductor is the substrate, it is also often the sensitizer. (WE and CE denote working and counter electrodes).

Such junctions mainly are of inorganic character, however, the dye present at the junction s interface still plays the central role in the initial formation of the charge separated state. The sensitizer takes on the role of both the light absorber and acts as the link between the two inorganic materials. The choice of inorganic wide band gap semiconductors applicable in such junctions is small, and only few... 

Solar cells, or photovoltaic devices, have been studied for many years [3], Most of the current work is focused on dye-sensitized nanocrystalline solar cells. These provide a technical and economically viable alternative to present-day photovoltaic devices. In contrast to conventional systems, in which the semiconductor assumes both the task of light absorption and charge carrier transport, the two functions are separated in dye-sensitized nanocrystalline solar cells [54] (cf. OPCs). Light is absorbed by the dye sensitizer, which is anchored to the surface of a wide-band-gap semiconductor. Charge separation takes place at the interface via photoinduced electron injection from the dye into the conduction band of the... 

This deformation can be followed by UV-vis spectroscopy directly at the air/water interface. Upon compression of the monolayer, the absorbance changes not very much around the point where the first increase in surface pressure is recorded (see Figure 6.17), This is caused by the disappearance of the voids between the domains. Above the kink in the isotherm, howevei the K-n band (-323 nm) decreases while the band at 248 nm increases. This increase is due to the increase in chromophore concentration upon compression of the monolayer. The decrease of the 7t-ic band is caused by a preferential orientation of the chromophorra perpendicular to the surface. Chromophores oriented perpendicularly are not detected because the transition dipole of the n-n band is parallel to the probing light. The band at 248 nm, however is not sensitive to the orientation of the chromophore, because the transition dipole moment has a component perpendicular to the long axis of the molecule (see Figure 6.17). 

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