Issue 7, 2016

Combining phosphonic acid-functionalized anchoring ligands with asymmetric ancillary ligands in bis(diimine)copper(i) dyes for dye-sensitized solar cells

Abstract

A ‘surfaces-as-ligands’ strategy is used to assemble heteroleptic copper(I) dyes [Cu(Lanchor)(Lancillary)]+ on FTO/TiO2 electrodes for dye-sensitized solar cells (DSCs). The anchoring domain, Lanchor, is either ((6,6′-diphenyl-[2,2′-bipyridine]-4,4′-diyl)bis(4,1-phenylene))bis(phosphonic acid) (1) or ((6,6′-dimethyl-[2,2′-bipyridine]-4,4′-diyl)bis(4,1-phenylene))bis(phosphonic acid) (2). Asymmetric ancillary ligands with a 2,2′-bipyridine metal-binding domain are used to counter the sterically-demanding 6,6′-diphenyl-substitution pattern in anchor 1; Lancillary = 6-methyl-4-phenyl-2,2′-bipyridine (3), 6-methyl-4-(4-bromophenyl)-2,2′-bipyridine (4), 6-methyl-4-(4-methoxyphenyl)-2,2′-bipyridine (5) or 6-methyl-4-(3,4,5-trimethoxyphenyl)-2,2′-bipyridine (6). Solid-state absorption spectra of adsorbed [Cu(1)(Lancillary)]+ and [Cu(2)(Lancillary)]+, and external quantum efficiency (EQE) spectra of DSCs containing these dyes confirm that incorporation of 6,6′-diphenyl-substituted 1 leads to a broadened spectral response at lower energies compared to dyes with anchor 2; dye-loading is higher for [Cu(2)(Lancillary)]+ than for [Cu(1)(Lancillary)]+, and EQEmax is >41% for [Cu(2)(Lancillary)]+ compared to <12% for [Cu(1)(Lancillary)]+. Enhanced values of the short-circuit current density (JSC) are observed on going from anchor 1 to 2, independent of Lancillary. For the series of [Cu(2)(Lancillary)]+ dyes, photoconversion efficiencies (confirmed using four DSCs per dye) vary with Lancillary in the order 35 > 6 > 4 on the day of DSC assembly, and 5 > 36 > 4 after a week. The best performing DSCs achieve efficiencies of ∼37% relative to N719 set at 100%.

Graphical abstract: Combining phosphonic acid-functionalized anchoring ligands with asymmetric ancillary ligands in bis(diimine)copper(i) dyes for dye-sensitized solar cells

Supplementary files

Article information

Article type
Paper
Submitted
30 nov 2015
Accepted
23 dec 2015
First published
12 jan 2016
This article is Open Access
Creative Commons BY license

RSC Adv., 2016,6, 5205-5213

Author version available

Combining phosphonic acid-functionalized anchoring ligands with asymmetric ancillary ligands in bis(diimine)copper(I) dyes for dye-sensitized solar cells

A. Büttner, S. Y. Brauchli, R. Vogt, E. C. Constable and C. E. Housecroft, RSC Adv., 2016, 6, 5205 DOI: 10.1039/C5RA25447G

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements