ELECTRIC-FIELD-INDUCED PHOTOLUMINESCENCE QUENCHING IN MOLECULARLY DOPED POLYMER LIGHT-EMITTING-DIODES

We present an experimental investigation of the spectral, field and co ncentration dependence as well as the ultrafast transient behavior of electric field-induced photoluminescence quenching in tris(stilbene)am ine (TSA) doped into polycarbonate (PC) and different polystyrene (PS) derivatives. The results are interpreted in terms of field-assisted d issociation of neutral excitations with a binding energy of E(b) appro ximate to 0.4 eV. Comparison with corresponding experimental data obta ined previously on the conjugated polymer poly(phenyl-p-phenylene viny lene) (PPPV) supports the notion that PPPV can be treated as an ensemb le of subunits with 'molecular' electronic properties. In view of the striking similarity between the behavior found in TSA and PPPV a band type model for PPV type conjugated polymers seems inappropriate.