Photovoltaic Properties and Long-Term Durability of Porphyrin-Sensitized Solar Cells with Silicon-Based Anchoring Groups

[Image: see text] Anchoring groups for dye-sensitized solar cells (DSSCs) play a decisive role in high-power conversion efficiency (η) and long-term cell durability. To date, a carboxylic acid is the most widely used anchoring group for DSSCs. However, the carboxylic acid tends to dissociate from a TiO(2) surface during the cell operation as well as in the presence of water. Considering that the dye dissociation from TiO(2) leads to a decrease in the cell performance, stable anchoring groups are highly desirable to achieve long-term durability of DSSCs toward their practical application. In this study, we designed and synthesized a series of porphyrin dyes with the triethoxysilyl anchoring groups, ZnPSi1, ZnPSi2, and ZnPSi3, to evaluate the effects of the silicon-based anchoring group on cell durability and photovoltaic properties. The DSSCs based on ZnPSi1, ZnPSi2, and ZnPSi3 exhibited moderate η-values of 2.2, 4.7, and 2.3%, respectively. It is noteworthy that the η-value of the DSSC based on ZnPSi2 (4.7%) is the highest among DSSCs based on porphyrin dyes with silicon-based anchoring groups. The moderate η-values are mainly attributed to the low charge collection efficiency originating from the low surface coverage and plausible tilted geometry of the dyes on TiO(2). More importantly, we demonstrated that the DSSC based on ZnPSi2 revealed higher long-term cell durability under illumination than that based on reference porphyrin YD2-o-C8 having a conventional carboxylic acid anchoring group.