In situ photopolymerization for making DSSC quasi solid electrolytes and assembling the cell

A feasible option for photovoltaic technology is represented by dye-sensitized solar cells (DSSCs): they have low cost, easy fabrication and good performance. The relevant technological drawbacks, i.e. scarce long-term stability, electrolyte evaporation, and permeability to H2O/O2 are mainly due to the presence of a liquid electrolyte. Therefore it was proposed to replace it with (quasi)-solid polymer electrolytes prepared by free-radical photopolymerization. Once the membrane was cured, it was swelled with the I−/I3− electrolyte solution and then assembled with the electrodes (a TiO2 photoanode sensitized with a dye and a transparent photocathode). An accurate characterization of a set of UV-cured membranes highlighted the influence of the chemical structure of the networks and their crosslinking density on the photo-electrochemical performances of the cells. Pursuing this work, in situ photopolymerisation was attempted: the in-situ process is efficient, suitable for scaling-up, can enable the creation of an excellent electrode/electrolyte interface and the sealing of the device. To overcome two major problems, namely the inhibition of radical photocuring by the I−/I3− redox couple and the damaging of the dye under UV-light, a selenocianated-based electrolyte was synthesized on purpose and visible light was used for curing through the photocatode. The DSSC prototype fabricated in this way showed promising photoharvesting properties.