Low-voltage organic electroluminescence device with an ultrathin, hybrid structure

We have prepared organic light-emitting diodes with a narrow recombination zone confined by an organic double-heterojunction structure using both polymer and small molecules (a hybrid structure). In these light-emitting diodes, we used very thin small molecule layers, down to a total thickness of 40 nm, to achieve an exponential forward characteristic. These layers were evaporated on a highly conductive layer of PEDT:PSS for a high-yield process and for good charge injection at the anode. Although no doping processes were applied during device fabrication, either at the injecting electrodes or in the Alq(3) layer, the diodes attained high brightness at very low voltage, for instance, 10.000 cd/m(2) at voltage of 4.7 V. (C) 2003 American Institute of Physics.