Photoexcitation dynamics in C60-doped PPV under bias illumination

We have studied photoexcitation dynamics in pristine and C60-doped PPV films under bias illumination by photoinduced absorption (PA), optically-detected magnetic resonance (ODMR), and electromodulated PA (EPA). Intrachain polaron pair species are the dominant excitations under these conditions. The polaron pairs on the polymer chains are identified in ODMR by the existence of an anisotropic spin- exchange interaction; their characteristics absorption spectrum is blueshifted with respect to that of isolated polarons by approximately 0.4 eV. We also identified the PPV+/C60 complexes by EPA spectroscopy.