Large enhancement of hole injection in pentacene by modification of gold with conjugated self-assembled monolayers

摘要

Planar diodes with gold electrodes and a pentacene semiconductor layer were made and electrically characterized. The gold electrodes were modified with self-assembled mono-layers of biphenylthiol and biphenylthiol substituted with a terminal fluorine atom (fluor-obiphenylthiol). Atomic force microscopy of the pentacene layer reveals large morphological similarities when the film is grown on gold modified with either of the two kinds of self-assembled monolayer. This is at variance with the significant increase of the current observed when the gold electrodes are treated with fluorobiphelylthiol, with a bulk mobility rising up to 1 cm~2/V s, while the treatment with biphelylthiol leads to a substantial decrease of the current. These results are interpreted in terms of adjustment of the injection barrier height as a result of the interface dipole induced by the self-assembled monolayer.