No abstract

An electrochemically stable and bistable switchable mirror is achieved for the first time by introducing a thiol-modified ITO electrode to stabilize the metallic film and ionic liquids as an anion-blocking layer, to achieve a long memory effect.

International audienceA polymethine dye was used as a fluorophore and an electroactive modulator in order to achieve reversible electrochemical fluorescence switching in the near infrared (NIR) region. An NIR emissive polymethine dye, 3H-indolium, 2-[2-[2-chloro-3-[2-[1,3-dihydro-3,3-dimethyl-1-(phenylmethyl)-2H-indol-2-ylidene]ethylidene]-5-(1,1-dimethylethyl)-1-cyclohexen-1-yl]ethenyl]-3,3-dimethyl-1-(phenylmethyl)-bromide (PM1), displayed high absorption and emission in the NIR region. In addition, it showed a relatively reversible electrochemical reaction between −0.5 and 1.1 V vs. Ag wire. In contrast, a keto group (C[double bond, length as m-dash]O) bridged polymethine analogue, 2,6-bis[2-(1,3-dihydro-1-hexyl-3,3-dimethyl-2H-indol-2-ylidene)ethylidene]-4-(1,1-dimethylethyl)cyclohexanone (PM2), showed an irreversible electrochemical reaction, possibly due to the keto group interrupting the full conjugation of the entire molecule in PM2. The reversible redox reaction of PM1 allowed electrochemical fluorescence switching in the NIR region for the first time. The NIR fluorescence switching was visually observable through a visible light cut-off filter with a cyclability of over 100

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. Photochemical cleavage of the oxadiazole in POD allowed photo-patterning of the POD film upon exposure to UV source. The patterned POD films displayed patterned image reversibly under a step potential of +1.8/-1.8 V.

A polymer switch was explored utilizing the redox reaction of iodide ions with highly fluorescent s-triazine (ST)-bridged p-phenylene vinylene (PPV) polymers. The fluorescent polymers were synthesized through the Wittig polycondensation to yield ST-bridged PPV polymers. Utilizing different quenching properties of the polymer with iodine derivatives, the fluorescence of the polymers was modulated electrochemically in a two-electrode device consisting of the fluorescent polymer-doped gel layer containing an iodide and iodine couple and a solid polymer electrolyte layer. The cell showed reversible multistate fluorescence switching in the working potential range of +2V.