3 research outputs found
A Synthetic Approach of New Trans-Substituted Hydroxylporphyrins
The synthesis of new trans A2B2-substituted porphyrins bearing oxygenic substituent (methoxy, acetoxy, hydroxy) at the periphery of the ring are
described. All of the synthesized products were characterized by 1H-N.M.R., 13C-N.M.R., and H.R.M.S. Electrochemical studies revealed two one-electron oxidations and two reductions. In addition, the X-ray structure of one methoxy-derivative was determined
“Spider”-Shaped Porphyrins with Conjugated Pyridyl Anchoring Groups as Efficient Sensitizers for Dye-Sensitized Solar Cells
Two novel “spider-shaped”
porphyrins, <i>meso</i>-tetraaryl-substituted <b>1PV-Por</b> and zinc-metalated <b>1PV-Zn-Por</b>, bearing four oligo(<i>p</i>-phenylenevinylene)
(oPPV) pyridyl groups with long dodecyloxy chains on the phenyl groups,
have been synthesized. The presence of four pyridyl groups in both
porphyrins, which allow them to act as anchoring groups upon coordination
to various Lewis acid sites, the conjugated oPPV bridges, which offer
the possibility of electronic communication between the porphyrin
core and the pyridyl groups, and the dodecyloxy groups, which offer
the advantage of high solubility in a variety of organic solvents
of different polarities and could prevent porphyrin aggregation, renders
porphyrins <b>1PV-Por</b> and <b>1PV-Zn-Por</b> very promising
sensitizers for dye-sensitized solar cells (DSSCs). Photophysical
measurements, together with electrochemistry experiments and density
functional theory calculations, suggest that both porphyrins have
frontier molecular orbital energy levels that favor electron injection
and dye regeneration in DSSCs. Solar cells sensitized by <b>1PV-Por</b> and <b>1PV-Zn-Por</b> were fabricated, and it was found that
they show power conversion efficiencies (PCEs) of 3.28 and 5.12%,
respectively. Photovoltaic measurements (<i>J</i>–<i>V</i> curves) together with incident photon-to-electron conversion
efficiency spectra of the two cells reveal that the higher PCE value
of the DSSC based on <b>1PV-Zn-Por</b> is ascribed to higher
short-circuit current (<i>J</i><sub>sc</sub>), open-circuit
voltage (<i>V</i><sub>oc</sub>), and dye loading values.
Emission spectra and electrochemistry experiments suggest a greater
driving force for injection of the photogenerated electrons into the
TiO<sub>2</sub> conduction band for <b>1PV-Zn-Por</b> rather
than its free-base analogue. Furthermore, electrochemical impedance
spectroscopy measurements prove that the utilization of <b>1PV-Zn-Por</b> as a sensitizer offers a high charge recombination resistance and,
therefore, leads to a longer electron lifetime