Resonant hot charge-transfer excitations in fullerene-porphyrin complexes: a many-body Bethe-Salpeter study

摘要

We study within the many-body Green's function GW and Bethe-Salpeterapproaches the neutral singlet excitations of the zinctetraphenylporphyrin andC70 fullerene donor-acceptor complex. The lowest transition is acharge-transfer excitation between the donor and the acceptor with an energy inexcellent agreement with recent constrained density functional theorycalculations. Beyond the lowest charge-transfer state, of which the energy canbe determined with simple electrostatic models that we validate, theBethe-Salpeter approach provides the full excitation spectrum. We evidence theexistence of hot electron-hole states which are resonant in energy with thelowest donor intramolecular excitation and show an hybrid intramolecular andcharge-transfer character, favouring the transition towards charge separation.These findings support the recently proposed scenario for charge separation atdonor-acceptor interfaces through delocalized hot charge-transfer states.