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Dye-sensitized solar cells with hole-stabilizing surfaces: “inorganic” versus “organic” strategies

Hostettler, N. and Wright, I. A. and Bozic-Weber, B. and Constable, E. C. and Housecroft, C. E.. (2015) Dye-sensitized solar cells with hole-stabilizing surfaces: “inorganic” versus “organic” strategies. RSC advances, 5. pp. 37906-37915.

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Official URL: http://edoc.unibas.ch/dok/A6381783

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Abstract

Two 2,2′:6′,2′′-terpyridine ligands (9 and 10) incorporating second-generation diphenylamino-dendrons have been synthesized and characterized; one ligand contains chromophoric benzothiadiazole domains. Using the ‘surface-as-ligand, surface-as-complex’ strategy, zinc(II)-containing sensitizers [Zn(Lanchor)(Lancillary)]2+ with carboxylic or phosphonic acid anchors (1 and 2, respectively) have been assembled and tested in n-type DSCs. The solid-state absorption spectra of dye-functionalized electrodes show a broad spectral response for all the dyes with enhanced intensity for those containing the benzothiadiazole units. However, the [Zn(Lanchor)(Lancillary)]2+ dyes perform poorly, exhibiting very low values of the short-circuit current density (JSC) and open-circuit voltage (VOC). The external quantum efficiency (EQE) spectra confirm that electron injection occurs, but EQEmax is ≤3%. Non-optimal positioning of the thiadiazole domain in the dye probably contributes to the poor performances. Screening of DSCs containing FTO/TiO2 photoanodes without adsorbed dye shows that they generate small short-circuit current densities and open-circuit voltages which contribute significantly to parameters reported for badly performing dyes. An organic dye 11, structurally similar to 10 and containing a 2-cyanoacrylic acid anchor, is also reported. This exhibits a broad and intense spectral response between 300 and 600 nm, and shows efficient electron injection over a broad wavelength range. DSCs containing 11 are stable over a 17 day period and show global efficiencies of 3.93–4.57% (ca. 70% with respect to N719 set at 100%). Ground state DFT calculations reveal that the HOMO in each of [Zn(1)(9)]2+, [Zn(2)(9)]2+, [Zn(1)(10)]2+, [Zn(2)(10)]2+ and 11 is localized on the peripheral diphenylamino units, allowing for hole-transfer to the reduced electrolyte. In 11, a major contribution from the 2-cyanoacrylic acid anchoring group appears in the LUMO manifold; however, while the LUMO in each zinc(II) dye is localized on anchoring ligand 1 or 2, it is concentrated close to the metal centre which may contribute to poor electron injection.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Constable)
05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Housecroft)
UniBasel Contributors:Housecroft, Catherine Elizabeth and Constable, Edwin Charles and Wright, Iain and Hostettler, Niklaus and Bozic Weber, Biljana
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:Royal Society of Chemistry
ISSN:2046-2069
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Identification Number:
Last Modified:31 Dec 2015 10:57
Deposited On:05 Jun 2015 08:53

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