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Identifier

000397579

Title

Βιομιμητικά υπερμοριακά συστήματα, σύνθεση και χαρακτηρισμός τους, για μετατροπή της ηλιακής ενέργειας

Alternative Title

Biomimetic supramolecular systems, synthesis and characterization, for solar energy conversion

Author

Ζερβάκη, Γαλάτεια Εμμ

Thesis advisor

Κουτσολέλος, Αθανάσιος

Reviewer

Αγγαρίδης, Παναγιώτης
Μήλιος, Κωνσταντίνος
Μητράκη, Άννα
Ταγματάρχης, Νικόλαος
Τρικαλίτης, Παντελεήμων
Χανιωτάκης, Νικόλαος

Abstract

Chlorophylls in plants are the antennae that nature uses not only for light harvesting, but for electron transfer processes during photosynthetic procedure, as well. Scientific community, inspired by natural photosynthesis, takes advantage of the properties of dyes, in order to design artificial systems for the conversion of solar energy into electricity or other forms of energy. The continuous improvement of the design and the efficiency of those artificial photoconversion systems requires the understanding of the fundamentals of these processes. Porphyrins are an important building block for developing artificial photoconversion systems, since they are already utilized from the natural photosynthetic center: the simplest mimicking unit of that center could be a porphyrin-derivative where an electron donor and an electron acceptor moiety are covalently linked or self-assembled via weak interactions. Porphyrins constitute the best choice as photosensitizers, because of their properties, for organic photovoltaics, especially in dye-sensitized solar cells (DSSCs) or in hybrid solar cells. It’s not a coincidence the fact that, two decades after the discovery of DSSCs, a porphyrin based sensitizer has exhibited one of the highest efficiencies (~ 13%) that have been reported so far. In this thesis, the synthesis of novel porphyrin based sensitizers, dyads and triads, are presented, for photovoltaic applications. The research consists of three parts. In the first one, the synthesis of a porphyrin dyad is reported, where porphyrin moieties are linked together through an esteric bond. The dyad, also, bears a carboxylic acid group as an anchor onto carbon nanohorns, providing a novel hybrid material. Its photophysical and photoelectrochemical properties are investigated. The second part includes the syntheses and DSSC measurements of novel porphyrin dyads, where the building blocks are connected to each other through a triazine moiety. These dyads consist of zinc-metallated porphyrin derivatives, or both zinc-metallated and free-base porphyrin moieties, containing one or two carboxylic acid groups for anchoring onto the surface of the semiconductor of DSSC. Finally, in order to include one more chromophore in the structure of the sensitizer, the syntheses of novel porphyrin triads dominate in the third part of the project: for the two of them the third chromophore is porphyrin, and the last one is, actually, a porphyrin – Bodipy complex, that exhibits the best efficiency (6.20%) among the presented compounds. In each triad, the chromophores are linked together through a triazine moiety, and also, bear one or two carboxyl units as anchoring groups. All these novel compounds exhibited in this project are fully characterized and their photoelectrochemical properties are investigated, after their photovoltaic application.

Language

Greek

Subject

Bodipy

Carbon nanohorn

DSSC

Dye

Hybrid material

Porphyrin

Porphyrin dyads

Porphyrin triads

Sensitizer