Thin films of three types of fullerene
derivatives were prepared through the electrospray deposition (ESD) method. The
optimized conditions for the fabrication of the thin films were investigated
for different types of fullerene derivatives: [6,6]-phenyl-C61-butyric
acid methyl ester, [6,6]-phenyl-C71-butyric acid methyl ester, and
indene-C60-monoadduct. The spray diameter during the ESD process was
observed as a function of the supply rate achieved by changing the applied
voltage. In all cases, the spray diameter increased with increasing applied
voltage, reaching the maximum diameter (Dmax)
in the voltage range 4 to 6 kV. It was clear that Dmax was influenced by the dipole moments of the
fullerene derivatives (as calculated by density functional theory methods).
Scanning electron microscopy observation of the fabricated thin films showed that imbricated structures were formed through the stacking
of the fullerene-derivative sheets. Atomic force microscopy images revealed
that the density of the imbricated structure was dependent on the spray diameter
during the ESD process, and the root-mean-square roughness of the film surface
decreased with increasing applied voltage. These findings suggest that the ESD
method will be effective for the preparation of fullerene-derivative thin films
for the production of organic devices.
Cite this paper
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