Characterization of self-assembled flexible multilayer electrode film by roll-to-roll process

In this paper, we report a self-assembled multilayer flexible electrode fabricated by a roll-to-roll sequential deposition process. We assembled the multilayer thin films consisting of weak polyelectrolyte poly(ethylenimine) (PEI) and conductive polymer polyaniline (PANi) on a polyethylene terephthalate) (PET) substrate via a roll-to-roll sequential deposition process. This fabricated multilayer electrode film showed stepwised growth with an agglomerated structure in accordance with the increase in the bilayer number of (PEI/PANi). The conductivity, morphologies, absorbance, and transmittance of electrode films were investigated using the four-terminal probes unit for current-voltage (I-V) characterization, atomic force microscopy (AFM), field-emission scanning electron microscopy (FE-SEM), and ultraviolet-visible (UV-vis) spectrometry. The prepared multilayer flexible electrode film with the coating sequence of (PEI/PANi)₃₀ showed high transmittance in a visible range and low surface roughness of ca. 9nm. The resistance of the multilayer electrode film was measured to be ca. 10kΩ. As the bilayer number of (PEI/PANi) increased from 10 to 30, the surface roughness and resistance of the multilayer electrode film decreased. These experimental results showed that the uniform and highly transparent conductive films were successively formed on a flexible PET substrate by a self-assembly roll-to-roll process.