Optically detected magnetic resonance (ODMR) and light-induced ESR (LESR) of fullerene-doped a-conjugated polymers

Summary form only given. The X-band LESR and ODMR of C/sub 60-/ and C/sub 70-/ doped derivatives of poly(p-phenylenevinylenes) (PPVs), poly(p-phenyleneacetylenes) (PPAs), and poly(3-alkylthiophenes) (P3ATs) are described and discussed. As in the undoped polymers, the ODMR of the 0.1 - 10 mol.% doped films consists of a narrow (/spl tilde12 G wide) photoluminescence (PL)-enhancing polaron resonance at g = 2.0031, and broad full field- and half-field-triplet exciton powder patterns. The polaron resonance is symmetric in the doped PPVs and PPAs and asymmetric in the P3ATs, as it is in the undoped films. The intensity of the narrow polaron resonance, which is very weak in the undoped PPV, sharply increases upon light (0.1 mol.%) C/sub 60/ or C/sub 70/ doping, but decreases upon heavier doping. In undoped PPA the narrow resonance is as intense as it is in the lightly doped films. UV irradiation of C/sub 60-/ doped PPV strikingly induces a narrow PL-quenching resonance. The results are discussed in relation to the nature of the doping- and photo-generated polarons and triplet excitons, which are believed to be stabilized at either native or Fullerene-induced defect sites, and the effects of photopolymerization on these excitations. It is thus suggested that the disorder in PPA is considerably greater than in PPV, and electrons and holes in the former rapidly decay into trapped polarons.