10.1021/ja0489285.s002
Ignacio Franco
Ignacio
Franco
Sergei Tretiak
Sergei
Tretiak
Electron-Vibrational Dynamics of Photoexcited Polyfluorenes
American Chemical Society
2004
molecules forms
vibronic degrees
photophysical properties
torsional distortions
motions couple
display applications
absorption
Photoexcited Polyfluorenes
emission properties
fluorescence frequencies
spectroscopic observables
dynamic
material
Delocalized excitations
photoexcited states
freedom
photoluminescence band shapes show
2004-09-29 00:00:00
Figure
https://acs.figshare.com/articles/figure/Electron_Vibrational_Dynamics_of_Photoexcited_Polyfluorenes/3323644
The highly polarizable π-electron system of conjugated molecules forms the basis for their unique
electronic and photophysical properties, which play an important role in numerous biological phenomena
and make them important materials for technological applications. We present a theoretical investigation
of the dynamics and relaxation of photoexcited states in conjugated polyfluorenes, which are promising
materials for display applications. Our analysis shows that both fast (∼20 fs) and slow (∼1 ps) nuclear
motions couple to the electronic degrees of freedom during the excited-state dynamics. Delocalized
excitations dominate the absorption, whereas emission comes from localized (self-trapped) excitons. This
localization is attributed to an inherent nonlinear coupling among vibronic degrees of freedom which leads
to lattice and torsional distortions and results in specific signatures in spectroscopic observables. Computed
vertical absorption and fluorescence frequencies as well as photoluminescence band shapes show good
agreement with experiment. Finally, we demonstrate that dimerization such as spiro-linking does not affect
the emission properties of molecules because the excitation becomes confined on a single chain of the
composite molecule.