Self-assembled monolayers (SAMs) of two tripod-shaped p-conjugated thiols and a disulfide have been grafted onto Au(111)/mica substrates. These SAMs exhibit oxidation and reduction peaks in the cyclic voltammograms arising from the electrochemical responses of the conjugated oligothiophene parts in the molecules. Organic light-emitting devices have been fabricated by using the SAM-coated Au electrode as the anode. In comparison with the device consisting of Au/TPD/Alq3/Mg-Ag, the electroluminescence performance of the device using the SAM grafted Au electrode is much improved for the SAM of the tripod-shaped thiols and worsened for the SAM of the disulfide. The different influences of the SAMs on the performances are explained by considering structures of the molecules and the SAMs, and the energy level alignment at the related interfaces in the devices.

Electropolymerization of aniline in perchloric acid solutions was investigated with presence of para-phenylenediamine (PPDA). Experimental results showed that the presence of PPDA promoted markedly the growth of the polymer. The catalytic effect of PPDA on the polymerization of aniline included its contributions to both the autocatalysis and the external catalysis. Addition of PPDA with an appropriate concentration resulted a polymer with high polymerization degree and higher conductivity, which were closely related to the contribution of PPDA to the autocatalysis in the polymerization of aniline. Memory effects in and else properties of the catalytically electrosynthesized polyaniline were also studied,

Electrochemistry of poly[(tetraethyldisilanylene)quinque(2,5-thienylene)] (DSST) has been investigated in acetonitrile with cyclic voltammetry, potentiostatic oxidation and spectroelectrochemical measurements. In multicycle voltammograms of a DS5T film there are a pair of redox peaks attributable to anion-doping and dedoping. During potential cycling or electrolyzing at certain positive potentials, the polymer is subject to decomposition to some extent. An irreversible oxidation subpeak for the decomposition of the polymer is observed in the first-cycle voltammogram with low scan rates. Spectroelectrochemical measurements demonstrate that the slow decomposition process tends to be inhibited by further oxidation of its decomposed product, followed by redepositing of a solid film onto the DS5T film. The further oxidation of the decomposed product also leads to some unexpected observations in the spectroelectrochemistry of DS5T. Moreover, if the forward potential scanning is returned at more positive potentials, two pairs of oxidation/reduction peaks occur in the cyclic voltammogram of DS5T and the polymer film becomes much more unstable at the potential of the second oxidation peak.

Self-assembled monolayers of a tripod-shaped conjugatedthiol grafted onto Au(111) substrates are found to show electrochemically reversible oxidation and reduction and to improve electroluminescence performances of organic lightemitting diodes.

Electrochemical oxidation of thin films of s-p-conjugated thienylene-silanylene copolymers, with poly[(hexamethyltrisilanylene) quinque(2,5-thienylene)] (TS5T) as a representative, is investigated in acetonitrile solutions containing different electrolytes. It is found from fluorescence spectroelectrochemical, electrochemical quartz crystal microbalance and FT-IR measurements that Si-Si-Si s-bonding is weakened by electrochemical anion doping in p-conjugated segments of the polymer, resulting in promotion of cleavage of the s-bonding in BF4 and PF6 solutions. Such a doping-enhanced cleavage of the Si-Si-Si bonding is relatively negligible in a ClO4 solution, suggesting some specific interaction between the Si atoms in the polymer chain and the F atoms in BF4 and PF6 anions. In a F solution, on the other hand, the polymer film undergoes electrochemical fluorination and:or chemical dissolution.