Dye sensitized solar cells: TiO2 sensitization with a bodipy-porphyrin antenna system.

A zinc porphyrin derivative (2) and zinc porphyrin-bodipy dyad (3) have been prepared and applied to dye-sensitized solar cells (DSSCs). On the basis of absorption and fluorescence excitation spectra, dyad 3 efficiently transfers energy from the bodipy to zinc porphyrin constituent. The 3-sensitized solar cell demonstrates higher solar spectral coverage, based on incident photon to current efficiency (IPCE) spectra, and an improved power conversion efficiency (eta = 1.55%) compared to that of the 2-sensitized cell (eta = 0.84%). The better performance of the 3-sensitized cell is attributed largely to the gain in spectral absorbance provided by the bodipy constituent of 3. Also evident, however, are secondary effects reflecting (a) fill-factor improvement and (b) a slight gain in porphyrin red-edge absorbance due to bodipy-conjugate formation.