jp9b00494_si_001.pdf (1.18 MB)
Computational Modeling of Exciton Localization in Self-Assembled Perylene Helices: Effects of Thermal Motion and Aggregate Size
journal contribution
posted on 2019-02-25, 00:00 authored by Alekos Segalina, Xavier Assfeld, Antonio Monari, Mariachiara PastoreThe effects of aggregation
on the excited-state properties in a
solution of perylene diimide self-assembled helix-like structures
of different sizes are investigated by means of first-principles density
functional theory (DFT), time-dependent DFT (TD-DFT), and classical
molecular dynamics (MD) simulations. Excited-state analysis based
on the one-particle transition density matrices is then used to study
the exciton nature and its delocalization as a function of the thermal
motion and aggregate size. Overall, the results point to a rather
small delocalization of the Frenkel excitonic state even in large
aggregates also related to a concerted motion of blocks of four monomers
along the MD trajectories. Although dynamic effects do not remarkably
affect the calculated position and shape of the absorption spectrum,
they cause the appearance of several low-energy states of charge-transfer
character and hence of weak intensity (dark states) that might be
populated along the ultrafast exciton relaxation process potentially
influencing the charge-separation processes in PDI-sensitized photoactive
heterointerfaces.
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charge-transfer characterone-particle transition density matricesSelf-Assembled Perylene Helicesultrafast exciton relaxation processdelocalizationExciton Localizationabsorption spectrumThermal MotionFrenkel excitonic stateExcited-state analysisresults pointComputational Modelingexcited-state propertiesDFTlow-energy statesperylene diimide self-assembled helix-like structuresfirst-principles densityAggregate Sizeexciton naturecharge-separation processesMD trajectoriesPDI-sensitized photoactive heterointerfacesTD-DFT
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