Halos show the path to perfection: peripheral iodo-substituents improve the efficiencies of bis(diimine)copper(i) dyes in DSCs

Abstract

DSCs containing simple copper(i) dyes with peripheral halo (X) ligands give global efficiencies >3% for X = I; a new strategy for stepwise surface dye assembly is demonstrated.

The beneficial effects of trifluoromethyl-substituents on the photoconversion efficiency of copper(i) dyes in dye-sensitized solar cells

“…8 17 and for the iodosubstituted dye previously reported. 21 However, it is clear from the stabilization of the HOMO and LUMO which accompanies the introduction of the CF 3 groups is key to the enhanced dye performance, and/or that electron recombination processes are hindered. We are currently undertaking an electrochemical impedance spectroscopic investigation of a range of copper(I) sensitizers in order to gain insight into relationships between 6,6 0 -substituted 2,2 0 -bipyridine ancillary ligands and trends in DSC performances.…”

“…21 The results of ground state DFT calculations indicate that the incorporation of peripheral iodo-substituents in the dye may result in improved electron transfer from the reduced electrolyte over the halo-substituted aryl ring to the sensitizer.…”

‘Surfaces-as-ligands, surfaces-as-complexes’ strategies for copper(I) dye-sensitized solar cells

“…In order to optimize atom efficiency and to facilitate the screening of libraries of surface-bound dyes, we have developed methods of stepwise assembly of surface-bound bis(diimine) copper(I) dyes. In a further extention of the 'complexes-asligands' methodology introduced by the Bologna group for the systematic and regiospecific synthesis of homo-and heterometallic complexes [19,20], we have developed a powerful 'surfaces-as-ligands, surfaces-as-complexes' strategy for the preparation of DSSCs and other interfacial heterojunction devices [21,22,23,24,25,26,27,28]. In this approach, a nanoparticulate TiO 2 surface is treated with an anchoring ligand (L anchor ) which possesses two orthogonal functionalities: one is the anchoring group which interacts with the semiconductor (metal oxide in our case) surface and the other is one that can bind a metal centre.…”

Heteroleptic copper(i) sensitizers with one versus two hole-transporting units in functionalized 2,9-dimethyl-1,10-phenanthroline ancillary ligands

“…The potential of copper(I) dyes was rst recognized by Sauvage and coworkers, 11 and in 2014, PCEs exceeding 3% (relative to z7.5% for reference dye N719) were achieved. 12,13 Homoleptic copper(I) complexes have also been used as redox mediators combined with ruthenium(II) sensitizers in DSCs. 14 The simplest copper(I) sensitizers are homoleptic complexes of type [Cu(L anchor ) 2 ] + in which L anchor is typically a diimine ligand bearing a carboxylic or phosphonic acid substituent to anchor the dye to the semiconductor surface.…”