NIR Electrofluorochromic Properties of Aza-Boron-dipyrromethene Dyes.

The photophysical properties of near-infrared (NIR) emissive aza-boron-dipyrromethene (aza-BDP) dyes incorporating nitrofluorene and alkoxy decorations were intensively investigated. Their highly reversible one-electron reduction process showed characteristic electrofluorochromic (EF) properties in the NIR range, depending on the substituents. The nitrofluorene ethynyl-substituted (Type I) dyes showed smaller EF effects than the alkoxy-containing (Type II) dyes because of the difference in their intrinsic fluorescence contrast between the neutral and reduced states (radical anion).

Switchable silver mirrors with long memory effects.

An electrochemically stable and bistable switchable mirror was achieved for the first time by introducing (1) a thiol-modified indium tin oxide (ITO) electrode for the stabilization of the metallic film and (2) ionic liquids as an anion-blocking layer, to achieve a long memory effect. The growth of the metallic film was denser and faster at the thiol-modified ITO electrode than at a bare ITO electrode. The electrochemical stability of the metallic film on the thiol-modified ITO was enhanced, maintaining the metallic state without rupture.

Electrofluorescence switching of tetrazine-modified TiO2 nanoparticles.

Highly fluorescent tetrazine-modified TiO2 nanoparticles were prepared by the reaction of triethoxysilane-appended chloroalkoxy tetrazine (ESTZ) with TiO2 nanoparticles through a condensation reaction between the surface hydroxyl groups of an electrode and the silane anchor group of ESTZ. The prepared electrodes were used as robust fluorescent layers for electrochemical fluorescence switching (electrofluorochromism) applications in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as a charge balancing mediator. The stable charge balancing mediator, TEMPO, in the electrolyte was found to be essential to reduce the intrinsic electron transport resistance of TiO2 in order to achieve reversible electrofluorescence switching.

Highly ordered poly(thiophene)s prepared in mesoporous silica nanoparticles.

Nanostructured PEDOT was synthesized using mesoporous silica as a nano-template. The polymerization of thiophene monomers was performed with an oxidant and mesoporous silica nanoparticles. The silica particles took essential role in absorbing monomers and oxidant molecules, and growth of polymers inside their pores.

Electrochemical fluorescence switching from a patternable poly(1,3,4-oxadiazole) thin film.

A highly soluble poly(1,3,4-oxadiazole) (POD) substituted with long alkyl chains was examined for electrochemical fluorescence switching. The high solubility of the polymers enabled a simple fabrication of an electrochemical cell, which showed reversible fluorescence switching between dark (n-doping) and bright (neutral) states with a maximum on/off ratio of 2.5 and a cyclability longer than 1000 cycles.

Electrochromic thin films from a redox active diarylethene by electrochemical polymerization.

A diarylethene substituted with 3,4-(propane-1,3-diyldioxy)thiophene (ProDOT) was synthesized to induce electrochemical deposition of diarylethenes. The ProDOT substituted diarylethene (BTFPP) showed reversible photochromism from colorless to purple upon exposure to a UV light and bleached to colorless by a visibly light. The oxidation potential of the new ProDOT substituted diarylethene was lower than that of the unsubstituted diarylethenes due to the electroactive ProDOT unit.