Functionalizable and electrically conductive thin films formed by oxidative chemical vapor deposition (oCVD) from mixtures of 3-thiopheneethanol (3TE) and ethylene dioxythiophene (EDOT)

Mixtures of 3-thiopheneethanol (3TE) and 3,4-ethylenedioxythiophene (EDOT) were used as the reactants for oxidative chemical vapor deposition (oCVD). Monomer (3TE : EDOT) feed ratios of (3 : 1), (3 : 2), (3 : 3), (2 : 3), and (1 : 3) were employed to obtain conductive polymer thin films with varying densities of hydroxyl pendant groups. The incorporation of both 3TE and EDOT units into the deposited films was confirmed by a combination of high resolution mass spectrometry, UV-visible-Near Infrared (UV-vis-NIR), and Fourier transform infrared (FTIR) spectroscopy, yielding conductive and -OH functionalized thin films. Theoretical analysis of the initial formation of dimers was studied by using density functional theory (DFT). The calculation predicts that the reaction of 3TE and EDOT is kinetically favored over the combination of two 3TE monomers. The pi-pi* transition observed at 425 nm in the UV-vis-NIR spectra of the 3TE polymerized film red shifts with increasing EDOT incorporation. This transition is observed at 523 nm in the film prepared using (1 : 3) a monomer feed ratio.