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.

Electroluminescence (EL) characteristics of the double-MPc-layered devices consisting of ITO/MPc1/MPc2/Alq3/Mg-Ag were investigated, where MPc1 and MPc2 represent two metallophthalocyanines and Alq3 stands for tris(8-quinolinolato)aluminum(III). A compatible double-MPc-layered structure led to a decreased hole-injection barrier at the ITO/MPc1 interface and an increased electronblocking ability of the MPc2 layer in the device. The EL efficiency of the device was improved further by using a 4,40-bis(m-tolyphenylamino) biphenyl (TPD) layer as an additional hole-transport layer due to its good electron-blocking ability. For the double-MPc-layered devices with a TPD layer, the EL performances were dependent primarily on the electronic structure of ITO/MPc1 interface rather than that of MPc1/ MPc2 or MPc2/TPD interface.

In aqueous acidic solutions, a higher peak current and a more positive peak potential for the first oxidation peak of polyaniline (PAN) compared with those obtained in a multicycle voltammogram was observed after holding at a sufficiently negative potential. This is referred to as a memory effect in PAN. An exception to this behavior was observed at low scan rate, when the peak potential in the first voltammogram can be less positive than that in the multicycle voltammogram. When the solvent was substituted by a mixture of water and some organic solvents, the first oxidation peak obtained in aqueous solution split into two subpeaks. The first subpeak, with a less positive peak potential, contributed strongly to the memory effect observed in PAN, but the second subpeak, with a more positive peak potential, was little influenced by holding in the reduced state. The exception mentioned above could be explained in terms of the existence of these two subpeaks if it could be shown that they were present for PAN in any solvent. These two subpeaks may reflect different structures in reduced PAN or be due to solvent effects on PAN intermediates during cycling.

Influences of an inserted hole-blocking bathocuproine (BC) layer were investigated on electroluminescence (EL) performances of organic light emitting devices with a configuration of ITO/BC/Alq3/Mg–Ag, where Alq3 is tris(8-quinolinolato)aluminum(III). Variations in the thickness of organic layers and bias voltages were found to alternate the emissive region from the BC layer to the Alq3 layer, resulting in shift of the emission wavelength in the EL spectra of the devices.

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.