3.5. Photoinjection in TiO2-Dye Complex
As the light shines on the surface of dye, the electron from the HOMO of
dye are excite to its LUMO after which the electron is moved to the
conduction band of semiconductor TiO2 [80]. This
transfer of electron could be of two types: direct photoinjection and
indirect photoinjection. The indirect transfer involves transition
HOMO-dye to LUMO-dye toCB-TiO2 whereas the direct
transfer comprises of transition HOMO-dye to CB-TiO2.
These two processes are sketched in figure 7.