Film-Forming Properties of Fullerene Derivatives in Electrospray Deposition Method

Kazumasa Takeshi, Kenji Takagi, Takeshi Fukuda, Teiji Chihara, Yusuke Tajima

Department of Functional Materials Science, Graduate School of Science and Engineering, Saitama University, Saitama, Japan.

DOI: 10.4236/jsemat.2013.31A012                

Abstract

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 (D_max) in the voltage range 4 to 6 kV. It was clear that D_max 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.

Keywords

Electrospray Deposition Method; Fullerene Derivative; Thin Film, Scanning Electron Microscope; Imbricated Structure; Atomic Force Microscope; Root-Mean-Square Roughness

Conflicts of Interest

The authors declare no conflicts of interest.

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