Electric field-induced photoluminescence quenching in molecularly doped polymer light-emitting diodes

We present an experimental investigation of the spectral, field and concentration dependence as well as the ultrafast transient behavior of electric field-induced photoluminescence quenching in tris(stilbene)amine (TSA) doped into polycarbonate (PC) and different polystyrene (PS) derivatives. The results are interpreted in terms of field-assisted dissociation of neutral excitations with a binding energy of E(b) approximate to 0.4 eV. Comparison with corresponding experimental data obtained previously on the conjugated polymer poly(phenyl-p-phenylene vinylene) (PPPV) supports the notion that PPPV can be treated as an ensemble 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.