Injection and strong current channeling in organic disordered media

We consider charge injection from a metal into amorphous organic molecular media with correlated disorder. It is shown that correlations, known to be essential for understanding the field dependence of the carrier mobility, also strongly influence the injection current distribution. In particular, we find that the injection hot spots are intrinsic for metal/organic interfaces, even for perfectly flat surfaces. The current density variations reach several orders of magnitude for realistic material parameters. The injection hot spots further induce current channels in the bulk of the material that extend a hundred nanometers beyond the injection surface. For electronic devices based on thin amorphous organic films, as are the organic light-emitting diodes, this current channeling is expected to have a serious impact on device characteristic and performance.