Electro modulated photo induced absorption of C60 doped MEH-PPV

We have studied the field induced absorption (FIA) spectra of C60 doped and undoped MEH-PPV films in the spectral range, hωp, of 0.2 to 4 eV, with and without CW illumination with photon energy above the optical gap Eg. For hωpp > Eg we measured the electroabsorption (EA) spectrum of the doped material with and without illumination and compared it with that of the undoped material. For hωp< Eg the dominant effect is the field induced modulation of the lifetime of the C60:PPV charge transfer complexes. This novel technique reveals three absorption bands at 0.4, 1.18 and 1.65 eV, which we assigned to bound pairs of C60−:PPV+ complexes.