Κυρίτσης Παναγιώτης, Αναπληρωτής Καθηγητής, Τμήμα Χημείας, ΕΚΠΑ
The aim of this work was the synthesis, characterization and investigation of Cu(I) complexes as photosensitizers for Dye Sensitized Solar Cells (DSSCs), Grätzel type. The synthesized complexes were heteroleptic, in order to take ad-vantage of the desired effects exerted by both types of ligands when coordinated to Cu(I). The ligands employed were chelating imidodiphosphinato anions of the general type [(XPR2)(YPR2)N], X, Y = O, S, Se; R, R = Ph, iPr, coordinating to Cu(I) by their chalcogen X and Y atoms, (X,Y). More specifically, the following ligands were used: [(SPPh2)N(SPPh2)] (L2), [(SPPh2)N(OPPh2)] (L3) and [(SePiPr2)N(SePiPr2)] (L4). Coordination of the soft Lewis acid Cu(I) by these soft ligands containing S or Se donor atoms, makes the complexes more stable towards undesired oxidation. The second type of ligands were diimines (N,N), such as the methyl ester of 2,2'-pyridyl-carboxykinoline (L5), 4,4'-di(furan-2-yl)-6,6'-dimethyl-2,2'-bipyridine (L6) and 6,6'-dimethyl-2,2'-bipyridine-4,4'-dicarboxylic acid (L7), which are coordinated to Cu(I) by their N atoms and bear the TiO2-anchoring groups. The heteroleptic complexes resulting from this com-bination of ligands were neutral, of the general type [Cu(I)(N,N)(X,Y)]. The char-acterization of the above complexes was carried out by various spectroscopic techniques, such as IR, 1H/31P-NMR, and UV-vis. The molecular structure of the [Cu(L2)(L5)] and [Cu(L2)(L6)] complexes was determined by single crystal X-ray crystallography. The [Cu(L2)(L6)] complex was also characterized by emission spectroscopy (fluorensce) and cyclic voltammetry. Last, a preliminary investiga-tion of [Cu(L2)(L6)] as a photosensitizer in a DSSC, showed similar reactivity with that of the corresponding homoleptic [Cu(L6)2]PF6 literature complex.
copper, imidodiphosphinato ligands, diimine ligands, photosensitizers