S. Barth et al., Current injection from a metal to a disordered hopping system. III. Comparison between experiment and Monte Carlo simulation, PHYS REV B, 60(12), 1999, pp. 8791-8797
We have performed electric-field and temperature-dependent electron injecti
on studies in an aluminum/tris(8-hydroxy-quinolinolato) aluminum/magnesium:
silver single-layer organic light-emitting diode. Analysis of the observed
injection currents in terms of the classic Fowler-Nordheim (FN) tunneling o
r Richardson-Schottky (RS) thermionic emission proved to be inadequate. Whe
reas, the FN-type behavior at high-electric fields must be considered accid
ental, the injection currents qualitatively resemble those of the RS concep
t. However, quantitative differences are observed concerning the RS coeffic
ient, the prefactor current, and the temperature dependence. On the other h
and, the experimental data are in excellent agreement with a recently prese
nted Monte Carlo simulation [U. Wolf et al., Phys. Rev. B 59, 7507 (1999)]
of carrier injection from a metal to an organic dielectric with random hopp
ing sites.