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A study of dye anchoring points in half-squarylium dyes for dye-sensitized solar cells

A study of dye anchoring points in half-squarylium dyes for dye-sensitized solar cells
A study of dye anchoring points in half-squarylium dyes for dye-sensitized solar cells
This paper reports the synthesis of a series of new half-squaraine dyes (Hf-SQ) based around a common chromophoric unit consisting of linked indoline and squaric acid moieties. Carboxylate groups have been incorporated onto this core structure at four different points to study the influence of the anchoring group position on dye-sensitized solar cell (DSC) device performance. Dyes have been linked to TiO2 directly through the squaric acid moiety, through a modified squaric acid unit where a vinyl dicyano group has replaced one carbonyl, via an alkyl carboxylate attached to the indole N or through a carboxylate attached to the 4 position of a benzyl indole. Contact angle measurements have been studied to investigate the hydrophobic/hydrophilic properties of the dyes and the results have been compared to N719 and Z907. Full characterization data of all the dyes and synthetic intermediates are reported including single-crystal X-ray structural analysis for dye precursors; the indole (2a) and the half-squarylium esters (3a) and (6b), as well as the dyes (4c), (8) and (12). Dye colours range from yellow to red/brown in solution (lambda(max) range from 430 to 476 nm) with 3 ranging from 38 000 to 133 100 M-1 cm(-1). The performance of the dyes in DSCs shows the highest efficiency yet reported for a Hf-SQ dye (eta = 5.0%) for 1 cm(2) devices with a spectral response ranging from 400 to 700 nm depending on the dye substituents. Co-sensitization of half-squarylium dye (7b) with squaraine dye (SQ2) resulted in a broader spectral response and an improved device efficiency (eta = 6.1%). Density functional theory (DFT) calculations and cyclic voltammetry have been used to study the influence of linker position on dye HOMO-LUMO levels and the data has been correlated with I-V and EQE data.
2050-7488
4055-4066
Connell, Arthur
14db3268-a050-49a5-bb3d-a77103ab596c
Holliman, Peter J.
6a747393-e1fa-485f-aa9e-b71c7cd31e56
Davies, Matthew L.
fd7f51fb-47be-4fe1-9359-5a7d1271b3fc
Gwenin, Christopher D.
453803ef-0231-459c-a8df-88a05f16fb05
Weiss, Sophie
29270bcc-ba76-41c7-8c05-7e164cbdb061
Pitak, Mateusz B.
eeb6a00f-2291-4376-830f-d30dfd607ed1
Horton, Peter N.
154c8930-bfc3-495b-ad4a-8a278d5da3a5
Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Cooke, Graeme
65cf9a42-0b3a-4b1e-9a36-4d928e9ce17c
Connell, Arthur
14db3268-a050-49a5-bb3d-a77103ab596c
Holliman, Peter J.
6a747393-e1fa-485f-aa9e-b71c7cd31e56
Davies, Matthew L.
fd7f51fb-47be-4fe1-9359-5a7d1271b3fc
Gwenin, Christopher D.
453803ef-0231-459c-a8df-88a05f16fb05
Weiss, Sophie
29270bcc-ba76-41c7-8c05-7e164cbdb061
Pitak, Mateusz B.
eeb6a00f-2291-4376-830f-d30dfd607ed1
Horton, Peter N.
154c8930-bfc3-495b-ad4a-8a278d5da3a5
Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Cooke, Graeme
65cf9a42-0b3a-4b1e-9a36-4d928e9ce17c

Connell, Arthur, Holliman, Peter J., Davies, Matthew L., Gwenin, Christopher D., Weiss, Sophie, Pitak, Mateusz B., Horton, Peter N., Coles, Simon J. and Cooke, Graeme (2014) A study of dye anchoring points in half-squarylium dyes for dye-sensitized solar cells. Journal of Materials Chemistry A, 2 (11), 4055-4066. (doi:10.1039/C3TA15278B).

Record type: Article

Abstract

This paper reports the synthesis of a series of new half-squaraine dyes (Hf-SQ) based around a common chromophoric unit consisting of linked indoline and squaric acid moieties. Carboxylate groups have been incorporated onto this core structure at four different points to study the influence of the anchoring group position on dye-sensitized solar cell (DSC) device performance. Dyes have been linked to TiO2 directly through the squaric acid moiety, through a modified squaric acid unit where a vinyl dicyano group has replaced one carbonyl, via an alkyl carboxylate attached to the indole N or through a carboxylate attached to the 4 position of a benzyl indole. Contact angle measurements have been studied to investigate the hydrophobic/hydrophilic properties of the dyes and the results have been compared to N719 and Z907. Full characterization data of all the dyes and synthetic intermediates are reported including single-crystal X-ray structural analysis for dye precursors; the indole (2a) and the half-squarylium esters (3a) and (6b), as well as the dyes (4c), (8) and (12). Dye colours range from yellow to red/brown in solution (lambda(max) range from 430 to 476 nm) with 3 ranging from 38 000 to 133 100 M-1 cm(-1). The performance of the dyes in DSCs shows the highest efficiency yet reported for a Hf-SQ dye (eta = 5.0%) for 1 cm(2) devices with a spectral response ranging from 400 to 700 nm depending on the dye substituents. Co-sensitization of half-squarylium dye (7b) with squaraine dye (SQ2) resulted in a broader spectral response and an improved device efficiency (eta = 6.1%). Density functional theory (DFT) calculations and cyclic voltammetry have been used to study the influence of linker position on dye HOMO-LUMO levels and the data has been correlated with I-V and EQE data.

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Published date: 29 January 2014
Organisations: Organic Chemistry: Synthesis, Catalysis and Flow, Chemistry, Faculty of Natural and Environmental Sciences

Identifiers

Local EPrints ID: 369224
URI: http://eprints.soton.ac.uk/id/eprint/369224
ISSN: 2050-7488
PURE UUID: 32178110-dcef-4395-9d00-82eb20e1ad2f
ORCID for Mateusz B. Pitak: ORCID iD orcid.org/0000-0002-3680-7100
ORCID for Peter N. Horton: ORCID iD orcid.org/0000-0001-8886-2016
ORCID for Simon J. Coles: ORCID iD orcid.org/0000-0001-8414-9272

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Date deposited: 30 Sep 2014 11:27
Last modified: 18 Feb 2021 16:54

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