Ultrafast Non-Forster Intramolecular Donor Acceptor Excitation Energy Transfer Articles uri icon

authors

publication date

  • April 2017

start page

  • 1688

end page

  • 1694

issue

  • 7

volume

  • 8

International Standard Serial Number (ISSN)

  • 1948-7185

abstract

  • Ultrafast intramolecular electronic energy transfer in a conjugated donor-acceptor system is simulated using nonadiabatic excited-state molecular dynamics. After initial site-selective photoexcitation of the donor, transition density localization is monitored throughout the S-2 -> S-1 internal conversion process, revealing an efficient unidirectional donor acceptor energy-transfer process. Detailed analysis of the excited state trajectories uncovers several salient features of the energy-transfer dynamics. While a weak temperature dependence is observed during the entire electronic energy relaxation, an ultrafast initially temperature-independent process allows the molecular system to approach the S-2-S-1 potential energy crossing seam within the first ten femtoseconds. Efficient energy transfer occurs in the absence of spectral overlap between the donor and acceptor units and is assisted by a transient delocalization phenomenon of the excited-state wave function acquiring Frenkel-exciton character at the moment of quantum transition.

keywords

  • phenylene ethynylene dendrimer; molecular-dynamics; temperature-dependence; organic semiconductors; electronic coherence; conjugated molecules; excitonic couplings; transfer pathways; building-blocks; excited-states