Self-doped polyanilines were electrochemically synthesized in aqueous acid solutions through the copolymerization of aniline (An) and aniline-2,5-disulfonic acid (ADSA) and the polymerization of ADSA alone. The voltammetry of the copolymers shows characteristics similar to those of conventional polyaniline (PAn), and the copolymers exhibit higher electrochemical activity at values of pH higher than about 4. The presence of ADSA inhibits significantly the growth of PAn. When the relative concentration of ADSA approaches unity, no solid film is able to deposit on the electrode surface. However, the polymerization of ADSA results in the formation of water-soluble poly-ADSA. Electric conductivities of poly-ADSA and poly-An-ADSA are in the magnitude of 10-1-10-2 and 10-0-101Scm-1, respectively, lower than that of conventional PAn, 10°-101S cm-1. The conductivity of poly-ADSA is found to show little pH dependence up to at least 9.

Electrochemical doping and in-situ UV-vis-NIR spectroelectrochemical properties of solid films of some s-p conjugated polymers consisting of alternating oligothienylene units and silylene units have been investigated in acetonitrile, while chemical doping of these polymers has been conducted in dichloroethane. The cyclic voltammograms of the films of these polymers show two couples of redox peaks in the potential range of 0-1.2 V. The doping-level measurements and the in-situ spectroelectrochemical measurements suggest that the repeat unit of the polymer chain is oxidized to the radical cation in the first-step oxidation, and to the dication in the second-step oxidation. In addition, the in-situ UV-vis-NIR measurements provide clear-cut evidence for the transitions from the radical cation to their p-dimers via a coupling reaction. The changes in the absorption spectra of the polymer films at different potentials are interpreted by considering the dimerization reaction of the radical cations to the p-dimers.

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.

Effects of metallophthalocyanines (MPcs) are systematically investigated on electroluminescence (EL) characteristics of ITOy MPcyTPDyAlq3yMg-Ag devices. A linear relationship is found between driving voltages of the devices and energies of the highest occupied molecular orbital (HOMO) level of MPcs, showing that the driving voltage of the device is substantially determined by the energy barrier for hole injection at the ITOyMPc interface. When an MPc having a higher HOMO level, such as CuPc or ZnPc, is selected as a hole transport material, the driving voltage of the device at a luminance of 100 cd my2 significantly reaches as low as 5.5 V compared with 7.8 V for the device without an MPc layer. The insertion of MPc layer leads to increasing of the EL output, but does not affect the EL efficiency of 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,