Are Alkynyl Spacers in Ancillary Ligands in Heteroleptic Bis(diimine)copper(I) Dyes Beneficial for Dye Performance in Dye-Sensitized Solar Cells?
The syntheses of 4,4′-bis(4-dimethylaminophenyl)-6,6′-dimethyl-2,2′-bipyridine (<b>1</b>), 4,4′-bis(4-dimethylaminophenylethynyl)-6,6′-dimethyl-2,2′-bipyridine (<b>2</b>), 4,4′-bis(4-diphenylaminophenyl)-6,6′-dimethyl-2,2′-bipyridine (<b>3</b>), and 4,4′-bis(4-dip...
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| Format: | Article |
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MDPI AG
2020-03-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/25/7/1528 |
| _version_ | 1797626572288557056 |
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| author | Guglielmo Risi Mariia Becker Catherine E. Housecroft Edwin C. Constable |
| author_facet | Guglielmo Risi Mariia Becker Catherine E. Housecroft Edwin C. Constable |
| author_sort | Guglielmo Risi |
| collection | DOAJ |
| description | The syntheses of 4,4′-bis(4-dimethylaminophenyl)-6,6′-dimethyl-2,2′-bipyridine (<b>1</b>), 4,4′-bis(4-dimethylaminophenylethynyl)-6,6′-dimethyl-2,2′-bipyridine (<b>2</b>), 4,4′-bis(4-diphenylaminophenyl)-6,6′-dimethyl-2,2′-bipyridine (<b>3</b>), and 4,4′-bis(4-diphenylaminophenylethynyl)-6,6′-dimethyl-2,2′-bipyridine (<b>4</b>) are reported along with the preparations and characterisations of their homoleptic copper(I) complexes [CuL<sub>2</sub>][PF<sub>6</sub>] (L = <b>1</b>–<b>4</b>). The solution absorption spectra of the complexes exhibit ligand-centred absorptions in addition to absorptions in the visible region assigned to a combination of intra-ligand and metal-to-ligand charge-transfer. Heteroleptic [Cu(<b>5</b>)(L<sub>ancillary</sub>)]<sup>+</sup> dyes in which <b>5</b> is the anchoring ligand ((6,6′-dimethyl-[2,2′-bipyridine]-4,4′-diyl)bis(4,1-phenylene))bis(phosphonic acid) and L<sub>ancillary</sub> = <b>1</b>–<b>4</b> have been assembled on fluorine-doped tin oxide (FTO)-TiO<sub>2</sub> electrodes in dye-sensitized solar cells (DSCs). Performance parameters and external quantum efficiency (EQE) spectra of the DSCs (four fully-masked cells for each dye) reveal that the best performing dyes are [Cu(<b>5</b>)(<b>1</b>)]<sup>+</sup> and [Cu(<b>5</b>)(<b>3</b>)]<sup>+</sup>. The alkynyl spacers are not beneficial, leading to a decrease in the short-circuit current density (<i>J</i><sub>SC</sub>), confirmed by lower values of EQE<sub>max</sub>. Addition of a co-absorbent (<i>n</i>-decylphosphonic acid) to [Cu(<b>5</b>)(<b>1</b>)]<sup>+</sup> lead to no significant enhancement of performance for DSCs sensitized with [Cu(<b>5</b>)(<b>1</b>)]<sup>+</sup>. Electrochemical impedance spectroscopy (EIS) has been used to investigate the interfaces in DSCs; the analysis shows that more favourable electron injection into TiO<sub>2</sub> is observed for sensitizers without the alkynyl spacer and confirms higher <i>J</i><sub>SC</sub> values for [Cu(<b>5</b>)(<b>1</b>)]<sup>+</sup>. |
| first_indexed | 2024-03-11T10:12:20Z |
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| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-11T10:12:20Z |
| publishDate | 2020-03-01 |
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| series | Molecules |
| spelling | doaj.art-ec9eae15bae64aa8859184008fb6e06b2023-11-16T14:28:31ZengMDPI AGMolecules1420-30492020-03-01257152810.3390/molecules25071528Are Alkynyl Spacers in Ancillary Ligands in Heteroleptic Bis(diimine)copper(I) Dyes Beneficial for Dye Performance in Dye-Sensitized Solar Cells?Guglielmo Risi0Mariia Becker1Catherine E. Housecroft2Edwin C. Constable3Department of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, CH-4058 Basel, SwitzerlandDepartment of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, CH-4058 Basel, SwitzerlandDepartment of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, CH-4058 Basel, SwitzerlandDepartment of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, CH-4058 Basel, SwitzerlandThe syntheses of 4,4′-bis(4-dimethylaminophenyl)-6,6′-dimethyl-2,2′-bipyridine (<b>1</b>), 4,4′-bis(4-dimethylaminophenylethynyl)-6,6′-dimethyl-2,2′-bipyridine (<b>2</b>), 4,4′-bis(4-diphenylaminophenyl)-6,6′-dimethyl-2,2′-bipyridine (<b>3</b>), and 4,4′-bis(4-diphenylaminophenylethynyl)-6,6′-dimethyl-2,2′-bipyridine (<b>4</b>) are reported along with the preparations and characterisations of their homoleptic copper(I) complexes [CuL<sub>2</sub>][PF<sub>6</sub>] (L = <b>1</b>–<b>4</b>). The solution absorption spectra of the complexes exhibit ligand-centred absorptions in addition to absorptions in the visible region assigned to a combination of intra-ligand and metal-to-ligand charge-transfer. Heteroleptic [Cu(<b>5</b>)(L<sub>ancillary</sub>)]<sup>+</sup> dyes in which <b>5</b> is the anchoring ligand ((6,6′-dimethyl-[2,2′-bipyridine]-4,4′-diyl)bis(4,1-phenylene))bis(phosphonic acid) and L<sub>ancillary</sub> = <b>1</b>–<b>4</b> have been assembled on fluorine-doped tin oxide (FTO)-TiO<sub>2</sub> electrodes in dye-sensitized solar cells (DSCs). Performance parameters and external quantum efficiency (EQE) spectra of the DSCs (four fully-masked cells for each dye) reveal that the best performing dyes are [Cu(<b>5</b>)(<b>1</b>)]<sup>+</sup> and [Cu(<b>5</b>)(<b>3</b>)]<sup>+</sup>. The alkynyl spacers are not beneficial, leading to a decrease in the short-circuit current density (<i>J</i><sub>SC</sub>), confirmed by lower values of EQE<sub>max</sub>. Addition of a co-absorbent (<i>n</i>-decylphosphonic acid) to [Cu(<b>5</b>)(<b>1</b>)]<sup>+</sup> lead to no significant enhancement of performance for DSCs sensitized with [Cu(<b>5</b>)(<b>1</b>)]<sup>+</sup>. Electrochemical impedance spectroscopy (EIS) has been used to investigate the interfaces in DSCs; the analysis shows that more favourable electron injection into TiO<sub>2</sub> is observed for sensitizers without the alkynyl spacer and confirms higher <i>J</i><sub>SC</sub> values for [Cu(<b>5</b>)(<b>1</b>)]<sup>+</sup>.https://www.mdpi.com/1420-3049/25/7/1528copperdye-sensitized solar cell2,2′-bipyridinealkynyl groupphosphonic acid anchor |
| spellingShingle | Guglielmo Risi Mariia Becker Catherine E. Housecroft Edwin C. Constable Are Alkynyl Spacers in Ancillary Ligands in Heteroleptic Bis(diimine)copper(I) Dyes Beneficial for Dye Performance in Dye-Sensitized Solar Cells? Molecules copper dye-sensitized solar cell 2,2′-bipyridine alkynyl group phosphonic acid anchor |
| title | Are Alkynyl Spacers in Ancillary Ligands in Heteroleptic Bis(diimine)copper(I) Dyes Beneficial for Dye Performance in Dye-Sensitized Solar Cells? |
| title_full | Are Alkynyl Spacers in Ancillary Ligands in Heteroleptic Bis(diimine)copper(I) Dyes Beneficial for Dye Performance in Dye-Sensitized Solar Cells? |
| title_fullStr | Are Alkynyl Spacers in Ancillary Ligands in Heteroleptic Bis(diimine)copper(I) Dyes Beneficial for Dye Performance in Dye-Sensitized Solar Cells? |
| title_full_unstemmed | Are Alkynyl Spacers in Ancillary Ligands in Heteroleptic Bis(diimine)copper(I) Dyes Beneficial for Dye Performance in Dye-Sensitized Solar Cells? |
| title_short | Are Alkynyl Spacers in Ancillary Ligands in Heteroleptic Bis(diimine)copper(I) Dyes Beneficial for Dye Performance in Dye-Sensitized Solar Cells? |
| title_sort | are alkynyl spacers in ancillary ligands in heteroleptic bis diimine copper i dyes beneficial for dye performance in dye sensitized solar cells |
| topic | copper dye-sensitized solar cell 2,2′-bipyridine alkynyl group phosphonic acid anchor |
| url | https://www.mdpi.com/1420-3049/25/7/1528 |
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