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

Abstract

Following former studies, the donor-acceptor combinations of -NH(2)-substituted porphyrin donor and the acceptors C, D, E, F, H and G, those of -OH-, -CH(3)- 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 -NH(2)-, -OH- and -CH(3)-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 -NH(2)-substituted porphyrins as donors combined with the acceptor G are the best systems.

Elementary Photoelectronic Processes at a Porphyrin Dye/Single‐Walled TiO2 Nanotube Hetero‐interface in Dye‐Sensitized Solar Cells: A First‐Principles Study

“…The adsorbed ZnPVB clearly shows considerable overlap with STNT states over a wide range of energies in both the VB and the CB, indicating strong electronic coupling between the two species at the interface, in good agreement with the above geometrical analysis. [29] These unoccupied adsorbate states clearly arise from a number of molecular orbitals with the LUMO character of isolated ZnPVB, originating from the energy level split of the single LUMO of ZnPVB upon its adsorption on the STNT. Of note are the introduced hybrid states in the band gap of the STNT, which are completely attributable to the adsorbed dye molecule.…”

“…In fact, before injection into the CB, the ground-state electron was first promoted to an excited state, which was confirmed by the adsorbate states in the CB of the STNT (see arrows in Figure 5). [29] These unoccupied adsorbate states clearly arise from a number of molecular orbitals with the LUMO character of isolated ZnPVB, originating from the energy level split of the single LUMO of ZnPVB upon its adsorption on the STNT. To distinguish those of the free dye molecule, the HOMO and split LUMOs of the adsorbed dye molecule are denoted as HOMOA C H T U N G T R E N N U N G (ads) and LUMOA C H T U N G T R E N N U N G (ads).…”

“…[19,20,46] The anatase TiO 2 (101) surface has been demonstrated to favorably adsorb dye molecules and to accept photoinduced electrons from excited dye molecules, and therefore, constituted the slab used to construct the STNT photoanode model. [29,32] Sandwich STNTA C H T U N G T R E N N U N G (m,0) was obtained by rolling up the (101) slab along the [101] direction.…”

Using phenoxazine and phenothiazine as electron donors for second-order nonlinear optical chromophore: Enhanced electro-optic activity

“…By contrast, the DE (CV) value of chromophore L2 is 1.52 eV. The narrower energy gap indicated easier charge transfer [29,43]. It can be concluded that the LUMO energy of chromophore L1 is 0.016 eV lager than chromophore L2 (À3.701 eV vs.À3.685 eV), while the HOMO energy of L1 is 0.104 eV larger than that of L2 (À5.104 eV vs. À5.208 eV).…”

“…The frontier molecular orbitals are often used to obtain information about the optical and electrical properties of molecules [43]. Fig.…”