Molecular dyads comprising metalloporphyrin and alkynylplatinum(II) polypyridine terminal groups for use as a sensitizer in dye-sensitized solar cells.

A new class of molecular dyads comprising metalloporphyrin-linked alkynylplatinum(II) polypyridine complexes with carboxylic acids as anchoring groups has been designed and synthesized. These complexes can sensitize nanocrystalline TiO2 in dye-sensitized solar cell (DSSC) studies. The photophysical, electrochemical, and luminescence properties of the complexes were studied and their excited-state properties were investigated by nanosecond transient absorption spectroscopy, with the charge-separated [Por(.-)-{(C≡C)Pt(tBu3 tpy)}(.+)] state observed upon excitation. Excited-state redox potentials were determined; the electrochemical data supports the capability of the complexes to inject an electron into the conduction band of TiO2 . The complexes sensitize nanocrystalline TiO2 and exhibited photovoltaic properties, as characterized by current-voltage measurements under illumination of air mass 1.5 G sunlight (100 mWcm(-2)). A DSSC based on one of the complexes showed a short-circuit photocurrent of 10.1 mAcm(-2), an open-circuit voltage of 0.64 V, and a fill factor of 0.52, giving an overall power conversion efficiency of 3.4 %.