Polymer electrolytes for dye-sensitized solar cells prepared by photopolymerization of PEG-based oligomers

We report on the preparation and characterization of novel polymer electrolyte membranes for quasi-solid dye-sensitized solar cells. New methacrylic–acrylic gel-polymer electrolytes were prepared by photo-polymerization of mono/di-functional monomers. The crosslinked films were self standing, transparent and flexible. They were swelled by an iodine–iodide solution, obtaining a stable gel, where the polymeric network acts as a cage to retain the liquid, preventing its evaporation. Such a system combines the cohesive property of a solid with the high ionic conductivity of a liquid. The evaluation of the structural and physical-chemical characteristics of the polymer, combined with the electrical characterization of the membranes by means of the electrochemical impedance spectroscopy, allowed us to investigate the structure/property relationship of the material. The electric characterizations of the solar harvester based on the gel-polymer electrolyte showed a maximum photovoltaic conversion efficiency of 4.41%. Moreover, a significant improvement in the durability of the device was demonstrated with respect to the liquid electrolyte-based counterpart.