Change search
ReferencesLink to record
Permanent link

Direct link
Cation-Dependent Photostability of Co(II/III)-Mediated Dye-Sensitized Solar Cells
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.ORCID iD: 0000-0001-5115-4593
Show others and affiliations
2015 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 44, 24704-24713 p.Article in journal (Refereed) PublishedText
Abstract [en]

The electrolyte composition has a significant effect on the performance and stability of cobalt-based, dye-sensitized solar cells (DSSCs). The stability of DSSCs incorporating Co(II/III) tris(bipyridine) redox mediator has been investigated over 1000 h under full solar irradiation (with UV cutoff) at a temperature of 60 °C, the main focus being on monitoring the photovoltaic performance of the device and analyzing the internal charge-transfer dynamics in the presence of different cation coadditives (preferably added as tetracyanoborate salts). A clear cation-dependence is shown, not only of the early light-induced performance but also of the long-term photostability of the photovoltage of the device. These light-induced changes, which are attributed to the promotion of electron injection and less electron recombination loss, by transient spectral and electrochemical studies at the TiO2/dye/electrolyte interface, indicate that the main cation effects involve the TiO2 surface electric field and energy-state distribution. By examining the stability of adsorbed and solvated dye during aging, it has been found that the dye photodegradation is probably responsible for the decline in the photovoltage and that this is extremely dependent on the nature of the cation coadditives in the electrolyte. It is therefore suggested that optimization of the electrolyte cation composition is essential for improving the stability of cobalt-based DSSCs.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2015. Vol. 119, no 44, 24704-24713 p.
National Category
Physical Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-181971DOI: 10.1021/acs.jpcc.5b06310ISI: 000364435200003ScopusID: 2-s2.0-84946547956OAI: oai:DiVA.org:kth-181971DiVA: diva2:902926
Funder
Swedish Research CouncilSwedish Energy Agency
Note

QC 20160212

Available from: 2016-02-12 Created: 2016-02-11 Last updated: 2016-05-17Bibliographically approved
In thesis
1. Electrolyte-Based Dynamics: Fundamental Studies for Stable Liquid Dye-Sensitized Solar Cells
Open this publication in new window or tab >>Electrolyte-Based Dynamics: Fundamental Studies for Stable Liquid Dye-Sensitized Solar Cells
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The long-term outdoor durability of dye-sensitized solar cells (DSSCs) is still a challenging issue for the large-scale commercial application of this promising photovoltaic technique. In order to study the degradation mechanism of DSSCs, ageing tests under selected accelerating conditions were carried out. The electrolyte is a crucial component of the device. The interactions between the electrolyte and other device components were unraveled during the ageing test, and this is the focus of this thesis. The dynamics and the underlying effects of these interactions on the DSSC performance were studied.

Co(bpy)32+/3+-mediated solar cells sensitized by triphenylamine-based organic dyes are systems of main interest. The changes with respect to the configuration of both labile Co(bpy)32+ and apparently inert Co(bpy)33+ redox complexes under different ageing conditions have been characterized, emphasizing the ligand exchange problem due to the addition of Lewis-base-type electrolyte additives and the unavoidable presence of oxygen. Both beneficial and adverse effects on the DSSC performance have been separately discussed in the short-term and long-term ageing tests. The stability of dye molecules adsorbed on the TiO2 surface and dissolved in the electrolyte has been studied by monitoring the spectral change of the dye, revealing the crucial effect of cation-based additives and the cation-dependent stability of the device photovoltage. The dye/TiO2 interfacial electron transfer kinetics were compared for the bithiophene-linked dyes before and after ageing in the presence of Lewis base additives; the observed change being related to the light-promoted and Lewis-base-assisted performance enhancement. The effect of electrolyte co-additives on passivating the counter electrode was also observed. The final chapter shows the effect of electrolyte composition on the electrolyte diffusion limitation from the perspectives of cation additive options, cation concentration and solvent additives respectively. Based on a comprehensive analysis, suggestions have been made regarding lithium-ion-free and polymer-in-salt strategies, and also regarding cobalt complex degradation and the crucial role of Lewis base additives. The fundamental studies contribute to the understanding of DSSC chemistry and provide a guideline towards achieving efficient and stable DSSCs.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2016. 171 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2016:27
Keyword
Dye-sensitized solar cells, Stability, Electrolyte, Cobalt redox couples, Additives
National Category
Physical Chemistry
Research subject
Chemistry
Identifiers
urn:nbn:se:kth:diva-187025 (URN)978-91-7729-013-1 (ISBN)
Public defence
2016-06-15, Sal K2, Teknikringen 28, KTH, Stockholm, 13:00 (English)
Opponent
Supervisors
Funder
Swedish Energy AgencySwedish Research Council
Note

QC 20160517

Available from: 2016-05-17 Created: 2016-05-16 Last updated: 2016-05-17Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Gao, JiajiaKloo, Lars
By organisation
Applied Physical Chemistry
In the same journal
The Journal of Physical Chemistry C
Physical Chemistry

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 34 hits
ReferencesLink to record
Permanent link

Direct link