Fragment based analysis of charge transfer excitons: insights into the structure-property relationship

Interfacial charge-transfer (CT) excitons mediate the charge separation in organic solar cells. We explored interfaces comprising fullerene acceptors and dual-band donor polymers. We varied size, relative positions and orientations of the donor and acceptor domains. The CT excitons were characterized according to size, localization, intensity, and energy. The edge-on orientation favors dissociation following relaxation to cold CT excitons. Dissociation of hot excitons is favored by the face-on orientation.