Molecular design of distorted push–pull porphyrins for dye-sensitized solar cells

Abstract

A series of distorted push-pull meso-substituted porphyrin analogues with different acceptor groups and additional electron-donating substituents are investigated as organic sensitizers for application in dye-sensitized solar cells (DSSCs) using density functional theory (DFT) and time-dependent DFT approach. The donor was modified by interchanging methyl group with methoxy and extending the p-conjugation. The acceptor group was assessed based on cyanoacrylic (A analogues) or methylenemalonic (B analogues) acid groups. Benchmark calculations using YD1 as reference indicated that the best method to depict the excitation energies was with TDxB97X-D exchange-correlation (xc) functional while the computational protocol for computing redox potentials was found to be with the M06-2X xc functional based on vertical DSCF method. The absorption spectra of all the porphyrin analogues were red-shifted and produced higher oscillator strengths, especially at the Q-bands as compared to the reference molecule. Among the analogues, A2-OMe and B2-OMe are good candidates for sensitizers in DSSCs due to its larger hyperpolarizabilities, better light-harvesting efficiencies, proper matching of the ground-state oxidation potentials with respect to the I À =I À 3 redox couple, and higher dipole moment of the adsorbed analogues. This study further enhances the role of theoretical calculations in the molecular design of sensitizers for DSSCs in an effort to produce a highly efficient dye.

meso-Aryl-substituted free-base porphyrins: formation, structure and photostability of diprotonated species

“…G(d) basis set by Pople et al [53]. The hybrid meta exchange correlation functional M06-2X was chosen since it is recommended for calculations dedicated to non-covalent interactions, and proved very effective in prediction of electronic and geometric structures of porphyrins [54,55]. Geometry optimization and vibrational analysis of the porphine adduct including two molecules of TFA (and/or acetic acid, HAc, as reference) was carried out in the gas phase without symmetry constraints.…”

“…DFT computations performed using the B3LYP and M06-2X functionals provided similar structural results, although energy of the porphyrin-TFA interaction was found about 10 % lower in the first case. However, the results reported in Table 5 refer only to the M06-2X functional, which has been particularly recommended in porphyrin structural calculations [54,55].…”

Computational Investigation of Acene-Modified Zinc-Porphyrin Based Sensitizers for Dye-Sensitized Solar Cells

“…This strongly indicates that the functional choice is highly system-specific, as suggested by De Angelis and others. 14, [88][89][90] In summary, the accuracy of the estimated parameters (i.e., GSOP and ESOP) is 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 It is not easy to find a single LAC structure that shows the most desirable values of LHE, inject G ∆ and CB ∆ . The balance of these parameters might be essential for achieving high performance.…”

Interaction of YD2 and TiO2 in dye-sensitized solar cells (DSSCs): a density functional theory study

“…ground state of the dye (E dye ) and the vertical transition energy (λ max ): E dye* =E dye − λ max . E dye can be approximated to two levels: first, by applying Koopman's theorem using the absolute value of the HOMO energy [65]; second, using the energy of the orbital that generates the transition associated with the band. The calculated E dye* and ΔG inject values for the Q, T, and B bands for DY2 in the gas and solvent phases are listed in Table 7.…”