dioxide (TiO2) based dye-sensitized solar cells (DSSCs) provide a
promising alternative to high cost silicon-based solar cells. Though TiO2 is
inexpensive, the production of this type of cell can be costly since expensive
materials are typically employed. Our research group is exploring the use of
first row transition metal-based chromophores in order to achieve
cost/efficiency ratios in DSSCs necessary for them to compete with fossil
fuels. My research involves the design and synthesis of iron(II)-based
chromophores for use as sensitizers in DSSCs.
series of iron(II) polypyridyl complexes have been designed to gain a better
understanding of the ultrafast dynamics of prospective chromophores in DSSCs. To
be an effective sensitizer the lifetime of a metal to ligand charge transfer
(MLCT) excited state of the chromophore must be sufficiently long lived for
injection into the semiconductor to occur. However, iron(II) polypyridyl
complexes intrinsically have short lived MLCT states due to ultrafast
deactivation to lower lying ligand field states.
have designed and prepared new terpyridyl ligands, in which steric hindrance
has been introduced to impose strain along a torsional coordinate in the
iron(II) adducts for the analysis of a proposed relaxation pathway of the
charge-transfer excited state. The synthesis of another set of iron(II)
polypyridyl complexes is currently underway. This series involves more flexible
polypyridyl ligands with which a more octahedral structure around an iron(II)
center may be achieved. The fundamental understanding that we hope to gain from
the analysis of these complexes is pertinent toward the development of iron(II)
based sensitizers in DSSCs.