Quantum dot sensitized solar cell (QDSSC) is considered to be a simple analogue of dye
sensitized solar cell (DSSC). The only apparent difference involves the replacement of the
organometallic or organic dyes with QD sensitizers such as CdS, CdSe, PbS, PbSe and InP.
Otherwise the basic cell mechanisms, including charge separation by the sensitizer, charge
transport in both the mesoporous electrode and the electrolyte, and the recombination paths
seem to be similar to those of DSSC. The replacement of dye sensitizers by QDs is motivated
by their absorption coefficient which is higher than most dyes, and the size confinement that
allows tailoring of their absorption spectrum. Moreover the use of QDs opens new
possibilities for third generation solar cell configurations such as multiple carrier generation
(MEG) and hot electron injection. However, in spite of their great potential, the conversion
efficiency of QDs sensitized solar cells has reached only ~6%, a low value compared with the
DSSC analogue. The rather low efficiencies of QDSSC were attributed mainly to the charge
separation and recombination processes at the TiO2/QD/electrolyte junctions