Quasiparticle Excitations and Band Structures in Organized Donor-Acceptor Copolymers*

I will present our recent study of the quasiparticle excitations and band structures in organized donor-acceptor copolymers. We employ many-body perturbation theory, which accounts for the polarization effects among polymers, to calculate the quasiparticle energies in bulk polymers. Our computed results are in excellent agreements with the photoemission spectra data. We discover two types of states supporting band transport in bulk copolymers: the conjugated bands and impurity states. The non-local exchange interactions are found to enhance the band transport of hole along the polymer axis, but hinder the transport across the chain. The polarization interactions are found to stabilize charge carriers and hinder band transport. Further, we discover that depending on the molecular arrangement, bulk copolymers sustain electron and hole transport in two orthogonal directions; the holes are most efficiently transported along the polymer and the pi-pi stacking directions, while the electrons are transport along the edge-to-edge stacking direction.