Imaging the Ultrafast Photoelectron Transfer Process in Alizarin-TiO2

In this work, we adopt a quantum mechanical approach based on time-dependent density functional theory (TDDFT) to study the optical and electronic properties of alizarin supported on TiO2 nano-crystallites, as a prototypical dye-sensitized solar cell. To ensure proper alignment of the donor (alizari...

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Bibliographic Details
Published in:Molecules (Basel, Switzerland) Switzerland), 2015-07, Vol.20 (8), p.13830-13853
Main Authors: Gomez, Tatiana, Hermann, Gunter, Zarate, Ximena, Pérez-Torres, Jhon Fredy, Tremblay, Jean Christophe
Format: Article
Language:English
Subjects:
Adsorption
Alternative energy sources
Anthraquinones - chemistry
dye-sensitized solar cell
Dyes
electronic flux density
Electrons
Imaging, Three-Dimensional
Investigations
Metal oxides
Models, Molecular
Molecular Conformation
Nanoparticles
optical spectra
Photochemical Processes
Solar energy
Spectrum Analysis
Thermodynamics
Titanium
Titanium - chemistry
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Summary:In this work, we adopt a quantum mechanical approach based on time-dependent density functional theory (TDDFT) to study the optical and electronic properties of alizarin supported on TiO2 nano-crystallites, as a prototypical dye-sensitized solar cell. To ensure proper alignment of the donor (alizarin) and acceptor (TiO2 nano-crystallite) levels, static optical excitation spectra are simulated using time-dependent density functional theory in response. The ultrafast photoelectron transfer from the dye to the cluster is simulated using an explicitly time-dependent, one-electron TDDFT ansatz. The model considers the δ-pulse excitation of a single active electron localized in the dye to the complete set of energetically accessible, delocalized molecular orbitals of the dye/nano-crystallite complex. A set of quantum mechanical tools derived from the transition electronic flux density is introduced to visualize and analyze the process in real time. The evolution of the created wave packet subject to absorbing boundary conditions at the borders of the cluster reveal that, while the electrons of the aromatic rings of alizarin are heavily involved in an ultrafast charge redistribution between the carbonyl groups of the dye molecule, they do not contribute positively to the electron injection and, overall, they delay the process.
ISSN:1420-3049
1420-3049
DOI:10.3390/molecules200813830