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.

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.

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.

Electrochemical copolymerization of aniline and aniline-2,5-disulfonic acid (ADSA) was carried out in HCI solutions. The presence of ADSA inhibited significantly the growth of polyaniline (PAn), although the voltammetry of the copolymer was still similar to that of conventional PAn. As the ADSA concentration increased, the deposition rate of the copolymer decreased rapidly and finally no solid film was deposited on the electrode surface. When the ADSA concentration was lower than-5 mM, the depression effect of ADSA on the growth rate of the copolymer is mainly due to its stronger adsorption at the electrode surface. For higher ADSA concentrations, the inhibiting effect of ADSA was dominated by its termination effects, which led to more soluble oligomers and in turn resulted in lower deposition efficiency. Electrolysis of ADSA solution might result in a water-soluble fully sulfonated PAn. aniline, aniline-2,S-disulfonic acid, copolymerization, polyaniline, water-soluble

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.