Resonance Raman Study of New Pyrrole‐Anchoring Dyes for NiO‐Sensitized Solar Cells

Abstract

Three dyes for p-type dye-sensitised solar cells containing a novel doubly anchored pyrrole donor group were synthesised and their solar cell performances were evaluated. Dye 1 was comprised of a phenyl-thiophene linker and a maleonitrile acceptor, which has been established as an effective motif in other push-pull dyes. Two boron dipyrromethane analogues, dyes 2 and 3, were made with different linker groups to compare their effect on the behaviour of these dyes adsorbed onto nickel oxide (dye|NiO) under illumination. The photoexcited states of dye|NiO were probed using resonance Raman spectroscopy and compared to dyes anchored using the conventional 4-aminobenzoic acid moiety (P1 and 4). All three components, the anchor, the linker and the acceptor group were found to alter both the electronic structure following excitation and the overall solar cell performance. The bodipy acceptor gave a better performance than the maleonitrile acceptor when the pyrrole anchor was used, which is the opposite of the triphenylamine push-pull dyes. The linker group was found to have a large influence on the short-circuit current and efficiency of the p-type cells constructed.

A Comparative Investigation of the Role of the Anchoring Group on Perylene Monoimide Dyes in NiO‐Based Dye‐Sensitized Solar Cells

“…This could be explained by a broadening of the peak at 650 nm, owing to a change in environment. A similar broadening was reported previously . It could, however, also originate from dye aggregates on the surface, for which the anion spectra are different from those for the monomers.…”

“…As imilar broadening was reported previously. [24] It could, however, also originate from dye aggregates on the surface,f or which the anion spectra are different from those for the monomers. The other dyes show very similar TA spectra (not shown) and kinetic traces (Figure 12).…”

“…which is aw eaker Lewis acid than Ti IV in TiO 2 .F or fast hole injection into the NiO valence band, the HOMO of the dye must mix with the valence band, which implies that the anchoring group orbitalsm ust give as ignificantc ontribution to the HOMO.T his is the opposites ituation for TiO 2 sensitizers, which must be composed of electron-deficient anchoring groupso n which the LUMO should be delocalized. [16] We have investigated the replacement of carboxylic acid by catechol, [17] carbodithioic acid, [17] phosphonic acid, [17] acetyla cetone( acac), [18] alkoxysilane [19] and other teams have investigated pyridine, [20][21][22] di(carboxylic acid)pyrrole, [23,24] hydroxamic acid, [25] and di(carboxylic acid)triazole [26] as alternative anchoring groups for NiO photocathodes.O wing to the scarcity of systematic studies on NiO anchoring groups, we have been interested to investigate the properties of as eries of dyes that differ only by the nature of the anchoring group ( Figure 1).…”

“…This is the opposite situation for TiO 2 sensitizers, which must be composed of electron‐deficient anchoring groups on which the LUMO should be delocalized . We have investigated the replacement of carboxylic acid by catechol, carbodithioic acid, phosphonic acid, acetyl acetone (acac), alkoxysilane and other teams have investigated pyridine, di(carboxylic acid)pyrrole, hydroxamic acid, and di(carboxylic acid)triazole as alternative anchoring groups for NiO photocathodes. Owing to the scarcity of systematic studies on NiO anchoring groups, we have been interested to investigate the properties of a series of dyes that differ only by the nature of the anchoring group (Figure ).…”

Dye-sensitized solar cells strike back

“…665,666 Typically, carboxylic acid anchoring groups are used; however, until recently, there has been little research into whether or not this is the best choice. 687 Alternative anchoring groups have been proposed, including pyridine, 571,626,650,667,668 di(carboxylic acid)pyrrole, 669,670 hydroxamic acid, 671 di(carboxylic acid)triazole, 638 catechol, 622 carbodithioic acid, 622 methyl phosphonic acid, 622 acetylacetone (acac), 668,672 alkoxysilane, 188 coumarin, 673 aniline, 668 phosphonic acid, 668 hydroxyqinoline, 668 and dipicolinic acid. 668 Phosphonic acid is one of the strongest binding groups and is resistant to both acid and base, but can present some synthetic challenges.…”