Lower hole-injection barrier between pentacene and a 1-hexadecanethiol-modified gold substrate with a lowered work function
2007; Elsevier BV; Volume: 9; Issue: 1 Linguagem: Inglês
10.1016/j.orgel.2007.07.006
ISSN1878-5530
AutoresKipyo Hong, Jong Won Lee, Sang Yoon Yang, Kwonwoo Shin, Hayoung Jeon, Se Hyun Kim, Chanwoo Yang, Chan Eon Park,
Tópico(s)Semiconductor materials and devices
ResumoWe used ultraviolet photoemission spectroscopy (UPS) to study the hole injection barrier at the interface between pentacene and a gold surface treated with 1-hexadecanethiol (HDT). Through these UPS in-situ experiments, we found that the energy barrier between HDT-modified gold and pentacene was 0.74 eV. This energy barrier was 0.11 eV smaller than that between bare gold and pentacene, despite the work function of HDT-modified gold being 1.08 eV lower than that of bare gold. This result does not follow the typical trend, whereby decreasing the work function of a metal increases the energy barrier. The observed behavior can be explained by two factors. First, the bare gold substrate exhibited a large interface dipole, whereas the HDT-modified gold did not. And second, pentacene on the HDT-modified gold substrate had a lower ionization energy than pentacene on bare gold. This finding can be explained in terms of the polarization energy related to the more crystalline structure of pentacene on the HDT-modified gold substrate, which was established by X-ray diffraction analysis. For comparison, we also measured the injection barrier between the amorphous organic semiconductor, N,N′-diphenyl-N,N′bis(1-naphthyl-1,1′-biphenyl-4,4′-diamine (α-NPD)), and HDT-modified gold.
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