Giant domain formation in Langmuir–Blodgett films based on Alkylammonium–Au(dmit)2 salt

The crossed polarized-light microscopy has revealed that the as-deposited LB film of the 2C14–Au(dmit)2 salt consists of giant domains of several hundred microns, which have a uni-axial molecular arrangement. By the electrochemical oxidation, the giant domains disappear and smaller domains of 5–10 μm appear. According to the atomic force microscopy (AFM) observation, the as-deposited film consists of domains of several microns but it appears that the observed domains are fragments formed by cracks generated in much larger domains, as seen by the shapes. It is hypothesized that there exist giant domains at the air/water interface but cracks are made during the transfer process. Thus, the uni-axial molecular arrangement is kept over the macroscopic range. Considering the random potentials set up by grain boundaries and/or defects, fabrication of the crack-free LB film is considered to be indispensable for realizing metallic properties down to much lower temperatures and global superconductivity.