Preparation of pyridinium iodide-grafted nano-silica and its application to nano-gel systems for dye sensitized solar cells

Abstract

Dye sensitized solar cells (DSSCs) have emerged as promising candidates for replacing silicon-based photovoltaics in the renewable energy field as it has advantages such as low-cost and simple preparation procedures. However, conventional DSSCs have shown a critical limitation for practical use because of durability problems arising from the liquid solvent used in devices. Therefore, it is still necessary to develop a technology that is stable in the long term. This study demonstrates a system of nano-gel silica electrolyte with pyridinium iodide grafts (PISi) and its application to DSSCs. The PISi has been synthesized by a two-step process starting from nano-silica, 2-(4-pyridylethyl)triethoxysilane, and iodoalkane. The prepared PISi was analyzed using thermogravimetric analysis and scanning electron microscopy. The performance of DSSCs with the PISi electrolyte was optimized by changing the iodoalkane chain length, electrolyte solvent, and iodide concentration in the electrolyte. We have compared the performance of DSSCs employing two different electrolytes: a typical liquid electrolyte cell and the PISi electrolyte. Power conversion efficiency of DSSCs with the liquid electrolyte was retained around half of the initial value after 100h. In contrast, PISi electrolyte-based devices have shown a consistent efficiency. From this result, we conclude that the PISi electrolyte helped to improve the long-term stability in DSSCs.