Density functional theory (DFT) and timedependent
DFT (TD-DFT) methodologies have been
applied in an attempt to improve the performance of
the dye YD2-o-C8 which is characterized by
11.9–12.7 % efficiencies. We aimed at narrowing
the band gap of YD2-o-C8 to extend the light
harvesting region to near IR. This was done through
replacing the porphyrin macrocycle by the tetraazaporphyrin
(porphyrazin) macrocycle, so that the
performances of the suggested cells could be
improved with Ti38O76, (TiO2)60, SiC, ZrO2, and
GaP semiconductor electrodes. The effects of modifying
the central macrocycle on cell performance are
confirmed in terms of FMOs, energy gaps, electrode
(VB and CB) edges, density of states (DOS), MEPs,
dipole moments, IP, EA, reorganization energies, UV–
Vis absorption, ULHE, Uinjection, and life times of the
excited states. Replacing porphyrin macrocycle by
porphyrazin macrocycle resulted in charge separated
states, unidirectional charge transfer, narrower band
gaps, increase of DOS nearby Fermi levels, asymmetric
polarization, delocalization of the negative charges
near the anchoring groups, efficient electron injection,
suppressing macrocycle aggregation, active dye
regeneration, longer life times of the excited states,
and inhibited dye recombination. Co-sensitizers are
suggested for near IR sensitization to improve the
photo-to-current conversion efficiency. Size ranges:
for dyes (0.1–1 nm), and for pore diameters of a dye
sensitized mesoporous film of TiO2 (2–50 nm). |
