A vibronic exciton model is developed to account for the spectral signatures of HJ-aggregates of oligomers and polymers containing donor-acceptor-donor (DAD) repeat units. In (DAD) π-stacks, J-aggregate-promoting intrachain interactions compete with H-aggregate-promoting interchain interactions. The latter includes Coulombic coupling, which arises from "side-by-side" fragment transition dipole moments as well as intermolecular charge transfer (ICT), which is enhanced in geometries with substantial overlap between donors on one chain and acceptors on a neighboring chain.
View Article and Find Full Text PDFA vibronic exciton model is introduced to describe the excited state band structure and associated absorption spectra of low bandgap donor-acceptor conjugated polymers. The Hamiltonian is represented in a diabatic basis consisting of Frenkel-like donor and acceptor fragment excitations as well as charge-transfer (CT) excitations between neighboring fragments. States are coupled to each other through electron and hole transfer as well as Coulombically, through interacting fragment transition dipole moments.
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