1 research outputs found
Fate of Photoexcited Molecular Antennae - Intermolecular Energy Transfer versus Photodegradation Assessed by Quantum Dynamics
The
present computational study aims to unravel the competitive
photoinduced intermolecular energy transfer and electron transfer
phenomena in a light-harvesting antenna with potential applications
in dye-sensitized solar cells and photocatalysis. A series of three
thiazole dyes with hierarchically overlapping emission and absorption
spectra, embedded in a methacrylate-based polymer backbone, is employed
to absorb light over the entire visible region. Intermolecular energy
transfer in such antenna proceeds via energy transfer from dye-to-dye
and eventually to a photosensitizer. Initially, the ground and excited
state properties of the three push–pull-chromophores (e.g.,
with respect to their absorption and emission spectra as well as their
equilibrium structures) are thoroughly evaluated using state-of-the-art
multiconfigurational methods and computationally less demanding DFT
and TDDFT simulations. Subsequently, the potential energy landscape
for the three dyads, formed by the π-stacked dyes as occurring
in the polymer environment, is investigated along linear-interpolated
internal coordinates to elucidate the photoinduced dynamics associated
with intermolecular energy and electron transfer processes. While
energy transfer among the dyes is highly desired in such antenna,
electron transfer, or rather a light-induced redox chemistry, leading
to the degradation of the chromophores, is disadvantageous. We performed
quantum dynamical wavepacket calculations to investigate the excited
state dynamics following initial light-excitation. Our calculations
reveal for the two dyads with adjusted optical properties exclusively
efficient intermolecular energy transfer within 200 fs, while in the
case of the third dyad intermolecular electron transfer dynamics can
be observed. Thus, this computational study reveals that statistical
copolymerization of the individual dyes is disadvantageous with respect
to the energy transfer efficiency as well as regarding the photostability
of such antenna