Two new polyimides (ODA‐PI and HDA‐PI) having 1,4‐phenylenediethynylene unit and octyloxy groups were synthesized. Judging from inherent viscosities of their precursor PAAs (1.42 and 1.62 dL · g?1), the two PIs were very high in molecular weight. Casting and thermal imidization of PAAs results polyimides with good‐quality films. They were stable up to 364 °C and showed no crystallites. UV‐vis and PL spectra in NMP solutions of both PIs showed maxima at 442 and 501 nm, respectively, while PL spectra in ≈10 µm thick films exhibited a maximum at 540 nm. CV indicates that two PIs were electrochemically active in redox region. The devices with construction of ITO/PEDOT/PIs/BAlq3/LiF/Al exhibited turn‐on voltages of 6.5 V in ODA‐PI and 7.5 V in HDA‐PI and emitted a bright bluish‐green light. ODA‐PI and HDA‐PI showed maximum luminescence of 256 and 316 cd · cm?2, respectively, at the same voltage of 12 V.
Electrochemical treatment of porous silicon (PS) in ethanol solution of Er(NO3)3 was investigated to obtain material suitable for optoelectronic application. The voltammograms of n+-type and p-type PS vs. an Ag/AgCl reference electrode were examined and compared with these of a Pt electrode. The basic cathode reactions were marked out the voltammograms: (i) the formation and the adsorption of atomic hydrogen; (ii) the formation of molecular hydrogen; (iii) the electrolysis of water and ethanol. No zones relating to on electrochemical transitions of Er ions were revealed on the voltammograms. Nevertheless, with the cathode polarization, the formation of an Er-containing deposit was observed at the surface of the cathode. The IR and SIMS analysis were used to study the composition of the deposits. The scheme of the electrochemical and chemical reactions at the cathode is discussed. 相似文献
Aqueous silicon dispersions are used to produce pyrotechnic time delay compositions. The propensity of silicon to react with water and to produce hazardous hydrogen gas must be suppressed. To this end, the effect of air heat treatment temperature on the rate of corrosion of silicon was investigated. It was found that four hour heat treatments at temperatures below 350 °C provided significant passivation. This is attributed to the removal of the hydroxyl groups present on the SiO2 surface scale layer. It was found that thickening the silica layer, by heat treatment at higher temperatures, causes a further reduction in the amount of hydrogen released. However, differential thermal analysis (DTA) studies showed that excessive silicon surface oxidation increased the ignition temperature and reduced the heat release of a near‐stoichiometric silicon‐lead chromate pyrotechnic composition. 相似文献