The Effect of Ionization Potential and Film Morphology on Exciplex Formation and Charge Generation in Blends of Polyfluorene Polymers and Silole Derivatives

Long-lived emission from an exciplex state is observed in a series of blend films of polyfluorene-triarylamine copolymers with silole derivatives. The energy of the exciplex emission is found to con-elate with the energy offset between the frontier orbitals of donor and acceptor, whereas the yield of the exciplex is more strongly influenced by blend film morphology. Charge separation occurs in these films, and the external quantum efficiency of photovoltaic devices is found to depend upon both the energetics and the morphology of the blend film.