Effects of Bulky Substituents of Push–Pull Porphyrins on Photovoltaic Properties of Dye-Sensitized Solar Cells

Abstract

To evaluate the effects of substituent bulkiness around a porphyrin core on the photovoltaic properties of porphyrin-sensitized solar cells, long alkoxy groups were introduced at the meso-phenyl group (ZnPBAT-o-C8) and the anchoring group (ZnPBAT-o-C8Cn, n = 4, 8) of an asymmetrically substituted push-pull porphyrin with double electron-donating diarylamino groups and a single electron-withdrawing carboxyphenylethynyl anchoring group. The spectroscopic and electrochemical properties of ZnPBAT-o-C8 and ZnPBAT-o-C8Cn were found to be superior to those of a push-pull porphyrin reference (YD2-o-C8), demonstrating their excellent light-harvesting and redox properties for dye-sensitized solar cells. A power conversion efficiency (η) of the ZnPBAT-o-C8-sensitized solar cell (η = 9.1%) is higher than that of the YD2-o-C8-sensitized solar cell (η = 8.6%) using iodine-based electrolyte due to the enhanced light-harvesting ability of ZnPBAT-o-C8. In contrast, the solar cells based on ZnPBAT-o-C8Cn, possessing the additional alkoxy chains in the anchoring group, revealed the lower η values of 7.3% (n = 4) and 7.0% (n = 8). Although ZnPBAT-o-C8Cn exhibited higher resistance at the TiO2-dye-electrolyte interface by virtue of the extra alkoxy chains, the reduced amount of the porphyrins on TiO2 by excessive addition of coadsorbent chenodeoxycholic acid (CDCA) for mitigating the aggregation on TiO2 resulted in the low η values. Meanwhile, the ZnPBAT-o-C8-sensitized solar cell showed the lower η value of 8.1% than the YD2-o-C8-sensitized solar cell (η = 9.8%) using cobalt-based electrolyte. The smaller η value of the ZnPBAT-o-C8-sensitized solar cell may be attributed to the insufficient blocking effect of the bulky substituents of ZnPBAT-o-C8 under the cobalt-based electrolyte conditions. Overall, the alkoxy chain length and substitution position around the porphyrin core are important factors to affect the cell performance.

ABC–ABC‐Type Directly meso–meso Linked Porphyrin Dimers

“…The TiO 2 electrodes and the sealed cells for photovoltaic measurements were prepared according to the literature. [12,21] An anocrystalline TiO 2 layer of 2 mm( d = 30 nm, PST30NR-D, GreatCell Solar) was coated on af luorine-doped tin oxide (FTO)-coated glass plate by as creen-printing method. Then, the submicrocrystalline TiO 2 layer of 4 mm( d = 400 nm, CCIC:PST400C, JGC-C&C) was formed on the top of the FTO.…”

Solar Cells Sensitized with Porphyrin Dyes Containing Oligo(Ethylene Glycol) Units: A High Efficiency Beyond 12 %

“…Among these dyes, porphyrins have the advantages of having structures that are easy to modify and outstanding light‐harvesting ability . Therefore, many donor–π–acceptor (D–π–A)‐type zinc porphyrins with outstanding efficiencies have been synthesized . Although many of the highly efficient DSSCs have been fabricated based on a Co 3+ /Co 2+ electrolyte, it is still desirable to develop efficient DSSCs based on the traditional I − /I 3 − electrolyte because of the simple cell fabrication procedure .…”

Theoretical Studies on the Structure, Optoelectronic and Photosensitizer Applications of NKX Class of Coumarin Dye Molecules

“…In this study, we are using NKX 2587 which is a donor‐π acceptor (D‐π‐A) system. The D‐π‐A systems have been widely studied for their sensitizing properties . These belong to a highly advantageous class of sensitizing systems due to their high molar extinction coefficients, low cost and diversity.…”