Electrode versus space-charge-limited conduction in organic light-emitting diodes

A criterion is established to distinguish electrode limited charge injection from a metal into a random organic dielectric from space charge limited current flow. The crucial material parameters are the charge carrier mobility and the zero field injection barrier. It rests upon parametrizing the injection current as a function of electric field, temperature, and injection barrier by mutual adjustment of the electron current injected across a Mg:Ag\Alq(3) electrode on the one hand and Monte Carlo simulation of the injection yield for a hopping system on the other hand. (C) 1999 American Institute of Physics. [S0003-6951(99)00340-X].