The 12 wt% Pt-deposited carbon nanotube electrode gives 10% higher voltages than 29 wt% Pt-deposited carbon black and reduces the Pt usage by 60% in polymer electrolyte fuel cells with hydrogen and oxygen.

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The microscopic mechanisms behind the very high mobility in rubrene single-crystal transistors achieved by interface treatments with self-assembled monolayers (SAMs) have been clarified by using field-induced electron spin resonance (FI-ESR). Clearly observed FI-ESR signals exhibit extremely narrow linewidths owing to the very high carrier mobility. The precise angular dependence of FI-ESR g values shows that crystallinity in the semiconductor channel is unchanged by the SAM treatments. The trapping time of charge carriers at the interface directly evaluated from the ESR linewidth greatly decreases from ∼700 to ∼60 ps concomitant with the remarkable improvement in mobility because of the SAM treatments.

In this paper, we synthesized a new type of poly(N-phenyl-2,7-carbazole)s with alkoxy groups or a diphenylamino group at o-, m-, or p-position of the N-phenyl group using the Ni(0)-catalyzed Yamamoto polymerization in high yields. The series of structural isomers were synthesized in order to optimize the interand intramolecular interactions. The electron-rich triethylene oxide groups or the triphenylamino groups were introduced to tune the HOMO energy levels. These polymers were characterized by 1 H NMR, 13 C NMR, IR, elemental analysis, GPC, TGA, UV-vis, fluorescence spectroscopy, and electrochemical analysis. All the polymers had enough high molecular weights to show a good solubility in common organic solvents and a good processability for making thin films. Deiodination of the terminal residual iodide of the polymers enhanced the fluorescent quantum yields in CHCl 3 (φ f (sol) ) 0.8). In the form of thin films, all the polymers displayed the fluorescence charts with emission bands around 430, 455, and 475 nm. Among the polymers, PmDPAC, PmpEHOC, PoDPAC, PopEHOC remarkably fluoresced blue (φ f (film) > 0.2). The strong fluorescence band around 430 nm for PmpEHOC and PoDPAC suggested a poor visibility, and 475 nm for PopEHOC resulted in an impure blue color emission, while the strong emission band around 455 nm for PmDPAC was appropriate for pure blue emission. Furthermore, the series of PDPAC polymers possessed higher HOMO energy levels than the other carbazole homopolymers.

Highly luminescent π-conjugated polymeric microspheres were fabricated through self-assembly of energy-donating and energy-accepting polymers and their blends. To avoid macroscopic phase separation, the nucleation time and growth rate of each polymer in the solution were properly adjusted. Photoluminescence (PL) studies showed that efficient donor-to-acceptor energy transfer takes place inside the microspheres, revealing that two polymers are well-blended in the microspheres. Focused laser irradiation of a single microsphere excites whispering gallery modes (WGMs), where PL generated inside the sphere is confined and resonates. The wavelengths of the PL lines are finely tuned by changing the blending ratio, accompanying the systematic yellow-to-red color change. Furthermore, when several microspheres are coupled linearly, the confined PL propagates the microspheres through the contact point, and a cascade-like process converts the PL color while maintaining the WGM characteristics. The self-assembly strategy for the formation of polymeric nano- to microstructures with highly miscible polymer blends will be advantageous for optoelectronic and photonic device applications.