Low-Symmetrical Zinc(II) Benzonaphthoporphyrazine Sensitizers for Light-Harvesting in Near-IR Region of Dye-Sensitized Solar Cells

Two ring-expanded naphthalocyanine-based sensitizers <b>NcS1</b> and <b>NcS2</b> have been designed and synthesized to harvest near-IR light energy in dye-sensitized solar cells. Low-symmetrical “push-pull” structures of <b>NcS1</b> and <b>NcS2</b> enable the red-shift of absorption spectrum as well as the defined Q-band splitting. The zinc benzonaphthoporphyrazine sensitizer <b>NcS1</b> possessing one carboxylic acid and six 2,6-diisopropylphenoxy units showed a PCE value of 3.2% when used as a light-harvesting dye on a TiO₂ electrode under one sun condition. The <b>NcS1</b> cell showed a broad photoresponse at wavelengths from 600 to 850 nm

Aggregation Control of Robust Water-Soluble Zinc(II) Phthalocyanine-Based Photosensitizers

A water-soluble zinc phthalocyanine (ZnPc) complex with four negatively charged electron-withdrawing sulfonic acid substituents at the nonperipheral positions (<b>α-ZnTSPc</b>) is found to have a high singlet oxygen (¹O₂) quantum yield and exhibits high photostability. The formation of aggregates is hindered and the highest occupied molecular orbital is significantly stabilized, making <b>α-ZnTSPc</b> potentially suitable for its use as a photosensitizer for photodynamic therapy and photoimmunotherapy. Atomic force microscopy (AFM) reveals that mixtures of the negatively charged <b>α-ZnTSPc</b> complex with a similar positively charged ZnPc were found to result in the self-assembly of one-dimensional accordion-like fibers. Supramolecular fibers can be formed in aqueous solutions through intermolecular electrostatic and donor–acceptor interactions between the two water-soluble ZnPcs