DFT/TD-DFT molecular design of porphyrin analogues for use in dye-sensitized solar cells
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Date
2008
Authors
Balanay, Mannix P.
Kim, Dong Hee
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Abstract
Density functional theory (DFT) and time-dependent DFT calculations have been employed to model Zn meso-tetraphenylporphyrin (ZnTPP) complexes having different b-substituents, in order to design an efficient sensitizer for dye-sensitized solar cells. To calculate the excited states of the porphyrin analogues, at least the TD-B3LYP/6-31G* level of theory is needed to replicate the experimental absorption spectra. Solvation results were found to be invariant with respect to the type of model used (PCM vs. C-PCM). Most of the electronic transitions based on Gouterman’s four-orbital model of ZnTPP-A and ZnTPP-B are p - p* transitions, so that cell efficiency can be enhanced by increasing the p-conjugation and electron-withdrawing capability of the bsubstituent.
This proposition was tested by inserting thiophene into the b-substituent of ZnTPP-A
to form a new analogue, ZnTPP-C. Compared with ZnTPP-A and ZnTPP-B, ZnTPP-C has a smaller band gap, which brings LUMO closer to the conduction band of TiO2, and a red-shifted absorption spectrum with higher extinction coefficients, especially in the Q-band position
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Keywords
dye-sensitized solar cells, Density functional theory, time-dependent DFT
Citation
Mannix P. Balanay, Dong Hee Kim; 2008; DFT/TD-DFT molecular design of porphyrin analogues for use in dye-sensitized solar cells; Physical Chemistry Chemical Physics; http://pubs.rsc.org/en/content/articlelanding/2008/cp/b806097e#!divAbstract