No abstract

Asymmetric zinc phthalocyanines with alkyl chain substituents formed highly efficient light-harvesting layers on a TiO2 surface. Dye-sensitized solar cells using PcS20 exhibited a record efficiency of 6.4% under one-sun irradiation.

A series of zinc-phthalocyanine sensitizers (PcS16-18) with different adsorption sites have been designed and synthesized in order to investigate the dependence of adsorption-site structures on the solar-cell performances in zinc-phthalocyanine based dye-sensitized solar cells. The change of adsorption site affected the electron injection efficiency from the photoexcited dye into the nanocrystalline TiO2 semiconductor, as monitored by picosecond time-resolved fluorescence spectroscopy. The zinc-phthalocyanine sensitizer PcS18, possessing one carboxylic acid directly attached to the ZnPc ring and six 2,6-diisopropylphenoxy units, showed a record power conversion efficiency value of 5.9 % when used as a light-harvesting dye on a TiO2 electrode under one simulated solar condition.

An achiral disk-shaped molecule (2) having one imidazole unit was found to be assembled into long and twisted nanoscopic fibers having 10 - 100 nm width as shown by transmission electron microscopy (TEM) and atomic force microscope (AFM). Compound 2 leads to spontaneous chiral symmetry breaking through the steric effect of imidazole units during the formation of one-dimensional stacks. The imidazole in 2 acts as a molecular adaptor to form hydrogen bonds and accumulate metal ions. The supramolecular connection of 2 with benzene-1,3,5-tricarboxylic acid through the hydrogen bonds exhibited a thermotropic liquid crystalline properties. Silver nanoparticles were deposited onto the self-assembled nanofibers by the photoreduction of silver ions.

Farbstoffe und ihre Empfindlichkeiten: Die Cosensibilisierung der TiO2‐Elektrode mit PcS15 und dem Farbstoff D131 ergibt einen drastisch erhöhten Photostrom für das gesamte sichtbare Spektrum. Somit steht ein einfacher Weg für die Entwicklung von Farbstoffsolarzellen offen.