Photo-induced charge separation process in (PCBM-C 120O)/(M3EH-PPV) blend solid film studied by means of X and K-bands ESR at 77 and 120 K

The new fullerene dimer adduct PCBM-C 120O was studied as an electron acceptor by light-induced ESR (LESR) when blended with the electron donor-conjugated polymer M3EH-PPV in a thin solid film. ESR parameters for the PCBM-C 120O anion radical and the M3EH-PPV polaron (triaxial g x, y, z factors) were determined by X- and K-band ESR techniques at temperatures of 77 and 120 K. It was found that isotropic g 0 of PCBM-C 120O anion radical ESR spectra obtained in this blend under illumination is close to g-factors of electrochemically reduced (C 120-O) − and does not coincide with the analogous parameter of (C 120-O) 2− (reported in literature). Spin relaxation parameters ( T 1 and T 2) of the PCBM-C 120O anion radical and M3EH-PPV positive polaron are similar to T 1, T 2 for light-induced ion radicals in the P3HT/PCBM blend.