Ethylene-polypropylene copolymer as an effective sealing spacer for dye-sensitized solar cells

Long-term stability is a major issue preventing the practical application of dye-sensitized solar cells (DSSCs). The DSSC stability problem relates to the sealing methods, which usually employ thermoplastic sealants. In the present study, a series of metallocene-catalyzed ethylene-polypropylene copolymers (EPCs) were prepared for application in DSSCs as sealing spacers. Different silane coupling agents and ethylene contents were investigated in the preparation of the EPCs to enhance the transparency, thermal-creep resistance, and strength of the adhesion to the glass substrate. The EPC films melted at ∼80 °C and exhibited strong adhesion to glass after cooling, along with a high thermal-creep resistance. The films were transparent, insulating, water-resistant, and noncorrosive to the iodine-based electrolyte. The DSSCs sealed with optimized EPC films exhibited excellent stability during an aging time of 3 days, retaining ∼98% of their initial efficiency, and were comparable to Surlyn. Therefore, the use of the EPC instead of the Surlyn polymer could drive substantial research interest for the commercialization of stable DSSCs with a low cost.