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 TiO2 surface during the cell operation as well as in the presence of water. Considering that the dye dissociation from TiO2 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 originatingfrom the low surface coverage and plausible tilted geometry of thedyes on TiO2. More importantly, we demonstrated that theDSSC based on >ZnPSi2 revealed higher long-term cell durabilityunder illumination than that based on reference porphyrin >YD2>-o>-C8 having a conventionalcarboxylic acid anchoring group.
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