Theoretical Screening of −NH2-, −OH-, −CH3-, −F-, and −SH-Substituted Porphyrins As Sensitizer Candidates for Dye-Sensitized Solar Cells

Following former studies, the donor−acceptor combinations of −NH2-substituted porphyrin donor and the acceptors C, D, E, F, H and G, those of −OH-, −CH3- and -Ph-substituted porphyrins as well as porphine donors and the acceptors E, G, and H, and those of −F- and −SH-substituted porphyrin donors and the acceptor G as novel sensitizer candidates have been designed and calculated at the density functional B3LYP level. The result shows that −NH2-, −OH- and −CH3-substituted porphyrins as donors combined with the acceptor G are very promising to provide good performances as sensitizers because of their smaller HOMO−LUMO gaps, much red-shifted absorption bands, and good frontier molecular orbital spatial distributions. They are all promising to challenge the current photon-to-current conversion efficiency record 7.1% of porphyrin-sensitized solar cells in which the −NH2-substituted porphyrins as donors combined with the acceptor G are the best systems.