Interface modification on TiO2 electrode using dendrimers in dye-sensitized solar cells

The interface modification of dye-sensitized solar cells (DSSCs) in order to remove I-3(-) on the TiO2 electrodes is important for improving their performance. The suppression of the back electron transfer by a modified interface improves the open-circuit voltage. In this study, we demonstrated that the suppression mechanism using phenylazomethine dendrimers with a triarylamine core (TPA-DPAs) and two other dendrimers, which are a carbazole dendrimer containing a cyclic phenylazomethine of the third generation (CPA-Cz G3) and a half-dendritic phenylazomethine of the fifth generation (Half-DPA G5). Removing I-3(-) and producing I- on the TiO2 electrode by complexation is critical for the suppression of the back electron transfer and promoting the regeneration of the dye in dendrimers having an inner space. Additionally, the presence of various metal compounds in the dendrimers decreased the resistance of the DSSCs, improving fill factor and energy conversion efficiency. We studied that the dendrimer property is changed by the quantitative metal complexation. The fill factor and energy conversion efficiency of the DSSCs are maximized with 0.5 equiv. of SnCl2 in the TPA-DPAs.