Surface smoothness and conductivity control of vapor-phase polymerized poly(3,4-ethylenedioxythiophene) thin coating for flexible optoelectronic applications

• Published in: Thin solid films 2008-07, Vol.516 (18), p.6020-6027
• Main Authors: Truong, Thuy Le, Kim, Dong-Ouk, Lee, Youngkwan, Lee, Tae-Woo, Park, Jong Jin, Pu, Lyongsun, Nam, Jae-Do
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electrical properties of specific thin films; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Fe(III)-tosylate polyethyleneterphthalate; Organic polymers; Physicochemistry of polymers; Physics; Poly(3,4-ethylenedioxythiophene); Properties and characterization; Surface conductivity and carrier phenomena; Vapor-phase polymerization
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2007.10.114

The surface morphology of poly(3,4-ethylenedioxythiophene) (PEDOT) was investigated in the vapor-phase polymerization of the thiophene monomer on a flexible polyethyleneterphthalate (PET) substrate film. The PET surface was modified with ethylene diamine maintaining the surface roughness within 2 nm to create amine and amide groups for the enhanced hydrophilic interaction with Fe(III)-tosylate (Fe(OTs) 3) and for the desirable hydrogen bonding with thiophene monomer as well as PEDOT. Polymerization rate was reduced by incorporating pyridine as a reaction retardant to control the surface roughness and conductivity of PEDOT thin films. The optimal conditions of pyridine and glycerol were found at a pyridine/Fe(OTs) 3 molar ratio of 0.5 and a glycerol concentration of 4–5 wt.%, respectively, providing the conductivity up to 500 S/cm and the surface roughness < 2 nm.