Improved long-term durability of a parallel-type dye-sensitized solar cell module using a platinum metal grid fabricated by direct current magnetron sputtering with heat treatment

A parallel-type grid module is used widely in the dye-sensitized solar cells (DSSCs). In most parallel-grid DSSC modules, silver (Ag) is used as the grid metal owing to its high conductivity. On the other hand, Ag is disadvantageous to the durability of the module because it readily undergoes corrosion from the iodide electrolyte that causes electrolyte degradation. In this study, a Ag grid in a parallel DSSC module is replaced by a platinum (Pt) grid to improve the stability of the parallel DSSC module. The Pt grid is fabricated by direct current magnetron sputtering with substrate heat treatment. Although the sheet resistance of the Pt grid is slightly higher than that of the Ag grid, the Pt grid is effective as a grid structure, reducing the internal series resistance in the DSSC. Furthermore, the durability of the Pt grid module is improved, maintaining 4.1% air mass (AM) 1.5 efficiency after 1700 h, because no electrolyte degradation or corrosion of the grid structure occurs.