Ultrafast bridge planarization in donor-π-acceptor copolymers drives intramolecular charge transfer.

ABSTRACT: Donor-π-acceptor conjugated polymers form the material basis for high power conversion efficiencies in organic solar cells. Large dipole moment change upon photoexcitation via intramolecular charge transfer in donor-π-acceptor backbone is conjectured to facilitate efficient charge-carrier generation. However, the primary structural changes that drive ultrafast charge transfer step have remained elusive thereby limiting a rational structure-function correlation for such copolymers. Here we use structure-sensitive femtosecond stimulated Raman spectroscopy to demonstrate that π-bridge torsion forms the primary reaction coordinate for intramolecular charge transfer in donor-π-acceptor copolymers. Resonance-selective Raman snapshots of exciton relaxation reveal rich vibrational dynamics of the

SUBMITTER: Roy P 

PROVIDER: S-EPMC5700982 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature