Exciton/Charge-Transfer Electronic Couplings in Organic Semiconductors.

Charge transfer (CT) states and excitons are important in energy conversion processes that occur in organic light emitting devices (OLEDS) and organic solar cells. An ab initio density functional theory (DFT) method for obtaining CT-exciton electronic couplings between CT states and excitons is presented. This method is applied to two organic heterodimers to obtain their CT-exciton coupling and adiabatic energy surfaces near their CT-exciton diabatic surface crossings. The results show that the new method provides a new window into the role of CT states in exciton-exciton transitions within organic semiconductors.