First Pseudohalogen
Polymer Electrolyte for Dye-Sensitized
Solar Cells Promising for <i>In Situ</i> Photopolymerization
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Abstract
The incorporation of selenocianated-based
redox couple in a polymer
electrolyte for dye-sensitized solar cells is reported for the first
time. The pseudohalogen redox mediator was integrated in two kinds
of acrylic/methacrylic membranes prepared by photocopolymerization
of multifunctional monomers. Before activation, the obtained membranes
were transparent, self-standing and flexible, and the physicochemical
characterizations of the films showed the formation of highly crosslinked
architectures. Membranes were activated by swelling in an optimized
solution containing the SeCN<sup>–</sup>/(SeCN)<sub>2</sub> redox mediator with 4-<i>tert</i>-butylpyridine in acetonitrile,
and the electrochemical behavior of the electrolytes revealed fast
charge transfer kinetics. The photovoltaic performances of quasi-solid
dye-sensitized solar cells were evaluated and compared with the results
of the liquid counterpart, showing promising photoharvesting properties.
No diminution in photoconversion efficiencies was evidenced in the
comparison between solid and liquid cells, demonstrating an optimal
kinetics of the redox species in the polymer cage, associated with
a noteworthy increase in device durability, as demonstrated by aging
tests. In addition, the <i>in situ</i> photopolymerization
in the presence of the redox mediator is presented with outstanding
results: this process, hardly feasible for the traditional I<sup>–</sup>/I<sub>3</sub><sup>–</sup> couple (inhibitor of radical polymerization
processes), enables at the same time the creation of an excellent
electrode/electrolyte interface and the sealing of the device