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One of the major drawbacks in dye-sensitized solar cells (DSSC) is related to the use of a liquid electrolyte, which limits durability and stability. Part of this problem can be solved by replacing the liquid electrolyte by a polymer or gel electrolyte, although the open circuit potential (V OC) of the solar cells is affected. In this work, the role of the reduced graphene oxide (RGO) added to a gel electrolyte in order to improve the efficiency of DSSCs is discussed in detail. The gel polymer electrolyte is composed of poly­(ethylene oxide) (PEO), γ-butyrolactone (GBL), LiI, I2, and different concentrations of RGO. The best solar cell using 0.5 wt % of RGO delivered an efficiency of 5.07 ± 0.97%, with the highest values of I sc and V OC. RGO sheets are acting as a multipurpose component in the electrolyte. The recovery of the V OC values can be related to the removal of polyiodide species from the photoanode surface by interaction with the RGO sheets. The increase in the I sc is assigned to the enhancement in the diffusion of I3 – species and by the reduction of the electron transfer resistance in the counter electrode.

Parallel, portable dye-sensitized solar cell modules with 5 × 5 cm2 of area containing either a polymer gel electrolyte or a standard liquid electrolyte were assembled and characterized as a function of time. For modules sealed with the thermoplastic Surlyn, a rapid loss of performance was observed, due to an insufficient protection of the metallic current collectors (silver grids) of the module and, sometimes, also associated with electrolyte leakage. Similar results were obtained using a glass frit layer as the only material for protective overcoat of the silver grids. Thus, the combination of the Surlyn with a glass frit was investigated. The process based on the combination of two materials allowed achieving a more effective sealing, with enhanced process yield and sample reproducibility. The modules assembled by this method, filled with either a polymer gel electrolyte or liquid electrolyte, showed an enhanced stability. Concomitantly, the formulation of the polymer gel electrolyte was also addressed and had to be tuned to allow an easier filling of the modules.

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