The impact of the Fermi-Dirac distribution on charge injection at metal/organic interfaces.
The Fermi level has historically been assumed to be the only energy-level from which carriers are injected at metal/semiconductor interfaces. In traditional semiconductor device physics, this approximation is reasonable as the thermal distribution of delocalized states in the semiconductor tends to dominate device characteristics. However, in the case of organic semiconductors the weak intermolecular interactions results in highly localized electronic states, such that the thermal distribution of carriers in the metal may also influence device characteristics. In this work we demonstrate that the Fermi-Dirac distribution of carriers in the metal has a much more significant impact on charge injection at metal/organic interfaces than has previously been assumed. An injection model which includes the effect of the Fermi-Dirac electron distribution was proposed. This model has been tested against experimental data and was found to provide a better physical description of charge injection. This finding indicates that the thermal distribution of electronic states in the metal should, in general, be considered in the study of metal/organic interfaces.
Wang
Z B
ZB
Department of Materials Science and Engineering, University of Toronto, 184 College St., Toronto, Ontario M5S 3E4, Canada. zhibin.wang@utoronto.ca
Helander
M G
MG
Greiner
M T
MT
Lu
Z H
ZH