Homoleptic and Heteroleptic Copper Complexes as Redox Couples in Dye‐Sensitized Solar Cells

Abstract

To gather a comprehensive understanding of copper complexes as redox couples in dye-sensitized solar cells (DSSCs), a series of copper complexes were synthesized and thoroughly characterized. Characterization was undertaken using an arsenal of spectroscopic techniques, including steady-state spectroscopy, electrochemical and spectroelectrochemical assays, currentvoltage measurements, electrochemical impedance spectroscopy (EIS), and transient absorption spectroscopy (TAS).Starting from a homoleptic copper complex featuring two bathocuproine ligands and replacing one of them by either another N-or a P-coordinating ligand, a clear relationship between ligand size, on one hand, and charge transport, recombination as well as effective regeneration of the sensitizer, on the other hand, was established. With this information in hand, the future targeted synthesis of copper complexes to achieve maximum device performance may be achieved.

Recent Advances on Copper Complexes as Visible Light Photoinitiators and (Photo) Redox Initiators of Polymerization

“…Prior to the polymerization tests, examination of the photochemical stability of the different complexes in solution revealed Cu-2 to be sensitive to the solvent polarity. Thus, irradiation at 405 nm of an acetonitrile solution of Cu-2 revealed the appearance of a new band in the UV-visible absorption spectrum, assigned to the formation of Cu(L2).BF4, consistent with the results previously reported in the literature [77,78]. Indeed, ligand displacement is sometimes observed for sterically hindered complexes upon photoexcitation, during the structural rearrangement from the initial octahedral geometry to the square planar geometry.…”

Cu(ii/i) redox couples: potential alternatives to traditional electrolytes for dye-sensitized solar cells

“…Lennert et al designed and synthesized a series of phenanthroline-based homoleptic and heteroleptic Cu(II/I) redox shuttles, which were tested in a DSSC using the D35 organic dye. 95 Initially, from a homoleptic copper complex containing bathocuproine ligands, [Cu(bcp) 2 ]OTf (bcp = 2,9dimethyl-4,7-diphenyl-1,10-phenanthroine) and [[Cu(bcp) 2 ]], one of them was substituted by another N-or P-coordinating ligand. They are [Cu(bcp)(tmp)]OTf, [Cu(bcp)(dppm)]OTf (dppm = (diphenylphosphino)methane), [Cu(bcp)(dppx)]OTf (dppx = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) and [Cu(dmp) 2 ]OTf.…”

Thermally activated delayed fluorescence in luminescent cationic copper(i) complexes

“…Cu, Co, Zn and Cr) have come into the limelight as viable alternatives to Pt, Ir and Ru complexes. 20,21 In particular, Cu(I) complexes show suitable photophysical and photochemical properties for various applications such as light-emitting devices, 16,19,22 dyesensitized solar cells, 23,24 water splitting, 25,26 photoredox catalysis, [27][28][29] polymerization, 30,31 among others.…”