Probing Donor鈥揂cceptor Interactions in meso-Substituted Zn(II) Porphyrins Using Resonance Raman Spectroscopy and Computational Chemistry

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• 作者：Holly van der Salm ; Samuel J. Lind ; Matthew J. Griffith ; Pawel Wagner ; Gordon G. Wallace ; David L. Officer ; Keith C. Gordon
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：October 1, 2015
• 年：2015
• 卷：119
• 期：39
• 页码：22379-22391
• 全文大小：609K
• ISSN：1932-7455

文摘

A series of Zn(II) porphyrins which have asymmetrically substituted meso groups have been studied with UV鈥搗is, resonance Raman, emission spectroscopies, and density functional theory (DFT) calculations. Dye-sensitized solar cells (DSSCs) of these materials have also been fabricated and their performance parameters measured. DFT calculations show perturbation of frontier molecular orbitals, and redox-active substituents cause greater perturbation than nonredox active substituents. All substituents cause a broadening of the B band, as is common for substituted porphyrins. TD-DFT calculations and resonance Raman spectroscopy suggest the donor and acceptor substituents play a small role in transitions of the B band. The meso donor substituent is electronically isolated and does not significantly perturb the molecular orbitals (MOs), while the meso cyanoacrylic acid TiO₂ binding group has a much larger effect on the e_g MO in particular. However, in the oxidized porphyrin species, the hole is located on the meso substituent, localizing it away from the semiconductor surface, which should reduce recombination and also improve performance. They show modest efficiency when incorporated into solar cells; however, the pattern of behavior is consistent with localization of charge at the meso unit.