The dye, which is typically a metallorganic Rucomplex, is excited by absorption of a photon.
Organic dyes like some indole derivatives,show the most rapid progress in the last few years and the efficiency today is almost the same as for Ru-complexes.
Other important dyes are porphyrin derivatives. This research is inspired by the porphyrin derivative chlorophyll, which absorbs light and transfers its energy to neighboring proteins in green leafs.
You can find the ifferent dyes are introduced in more detail at the end of this chapter.