A highly cross-linked polyviologen hydrogel, poly(tripyridiniomesitylene) (PTPM), has been designed as an anode-active material. It displays a reversible two-electron redox capability at -0.4 and -0.8 V vs Ag/AgCl in an aqueous electrolyte. The PTPM layer coated on a current collector by electropolymerization via a 4-cyanopyridinium electro-coupling reaction demonstrates a rapid charging-discharging reaction with a redox capacity comparable to that obtainable using the formula weight-based theoretical density, because of the combination of the redox-active viologen moieties built into the hydrogel. A test cell that has been fabricated using the developed PTPM anode, a poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl acrylamide) (PTAm)-based cathode, and an aqueous electrolyte exhibits a discharging voltage of 1.1 and 1.5 V, and has proven its ability to be recharged more than 2000 times.

Photochromic solid materials based on the cationic polymer poly­(decylviologen) are reported. The solids were obtained by freeze-drying colloidal suspensions of nanocomplexes obtained by mixing aqueous solutions of the polycation with different solutions of polyanions such as poly­(sodium 4-styrenesulfonate) or sodium alginate, at a cationic/anionic polymeric charge ratio of 0.7. The photochromic responses of the solid materials fabricated with alginate as complementary charged polyelectrolyte of the cationic polyviologen are faster than those of the solid materials fabricated with poly­(sodium 4-styrenesulfonate), achieving coloration kinetics in the order of minutes, and discoloration kinetics in the order of hours for the former. Aromatic–aromatic interactions between the latter polyanion and the polyviologen may stabilize the dicationic form of the viologen derivative, increasing the necessary energy to undergo photoreduction, thus decreasing the reduction kinetics.

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An indoline dye-coupled polyviologen was designed as a possible photoanode material for organic photovoltaic cells. A new donor–acceptor (D–A) coupled molecule (CVD131) was immobilized on a current collector by the reductive electropolymerization of its two cyanopyridinium moieties. The formed polyviologen could efficiently accept an excited electron from the indoline dye moiety.