Do Counter Electrodes on Metal Substrates Work with Cobalt Complex Based Electrolyte in Dye Sensitized Solar Cells?

Miettunen, Kati; Saukkonen, Tapio; Li, Xiaoe; Law, Chun Hung Roberts; Sheng, Yeo Kee; Halme, Janne; Tiihonen, Armi; Barnes, Piers R. F.; Ghaddar, Tarek H.; Asghar, Muhammad Imran; Lund, Peter; O’Regan, Brian C.

doi:10.1149/2.074302jes

Cited by 33 publications

(55 citation statements)

References 22 publications

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“…[34][35][36] The two blue curves in Fig. 9 are otherwise identical but have a different initial concentration of iodine because the commercial electrolyte used in 34,35,36,24 Fig. 9 it is clear that the cells containing purified MPN are not less stable than the cells of Asghar et al -actually, the slopes are remarkably similar before the 85 UV 1Sun h point.…”

Section: (Ncs)(h 2 O)] [Rul 2 (Ncs)(mpn)] [Rul 2 (Ncs)(nmbi)] [Rulmentioning

confidence: 91%

The Effect of Electrolyte Purification on the Performance and Long-Term Stability of Dye-Sensitized Solar Cells

Tiihonen

Miettunen

Rendon

et al. 2015

J. Electrochem. Soc.

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In this study the effect of the purification of electrolyte material on the performance and long-term stability of dye-sensitized solar cells is investigated. The combined effect of purifying all the electrolyte materials has been examined, as has the effect of purifying each compound to identify those compounds worth purifying and to eliminate unnecessary production steps on an industrial scale. Statistical methods were employed to draw statistically significant conclusions from the experimental results. No effect on the initial cell performance is found in this study. The purity of the electrolyte solvent (here methoxypropionitrile) is shown to have a remarkable effect on the cell lifetime: it could even double when the cell is properly purified. It is shown that exposing the cell to even relatively small amounts of UV light resulted in cell degradation through electrolyte bleaching during a 1000 hour aging test. Here the impurities in the electrolyte solvent lead to an almost doubled rate of electrolyte bleaching under UV light. Dye-sensitized solar cells (DSSC) have the potential to become a low-cost alternative to silicon solar cells in the future. They can be made out of sustainable materials, they have a wide application area, and they are on the threshold of large-scale production.1 They are also efficient: an 11.9% efficiency record for DSSCs has been achieved.2 At the moment one of the main challenges is the cell stability. DSSC stability for approximately 20 years in outdoor conditions is an essential prerequisite for the introduction of DSSCs into the wide commercial market, e.g., in the form of building-integrated panels. The structure of DSSCs is quite complicated and unfortunately the components tend to age when the DSSC is exposed long-term to light, humidity, and extreme temperatures. 3,1,4,5,6,7,8 Material purification has been proposed to increase the stability of the cells.9-12 The use of highly pure materials is also regarded as an essential step in the preparation of most efficient cells. 13,10,14 The reported data do not, however, include direct comparisons of purified and unpurified materials, which would be essential for assessing the importance of material purification in cell fabrication. From the industrial point of view, material purification increases the production costs of the cells. Thus the necessity of material purification should be studied carefully, 1,15 just like any step that increases the complexity of the production. The objective of this study is to investigate if cell efficiency and stability increase as a result of the purification of the electrolyte material. The effect of the purification of all the electrolyte materials has been studied and the effect of each compound has been statistically compared and analyzed. The research continues in, 16 where the effect of dye purification on cell efficiency and lifetime is studied.It is still quite common in the field to utilize only a few tests, mainly IV curve measurements in aging studies, or to test the cells only at the...

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Section: (Ncs)(h 2 O)] [Rul 2 (Ncs)(mpn)] [Rul 2 (Ncs)(nmbi)] [Rulmentioning

confidence: 91%

The Effect of Electrolyte Purification on the Performance and Long-Term Stability of Dye-Sensitized Solar Cells

Tiihonen

Miettunen

Rendon

et al. 2015

J. Electrochem. Soc.

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“…10,12 Here the focus is not if cobalt based cells are stable or not, but does the cobalt electrolyte corrode ferritic steel or not. Previous study has shown that even cobalt complex electrolyte can corrode some metals such as copper and zinc.…”

Section: Stability Of Counter Electrode Made On Ferritic Steelmentioning

confidence: 99%

“…yellow redox couple 2,3,5,7,8 and/or results in a non-transparent corrosion product (typically very dark) that can be dispersed in the electrolyte or accumulated on the surfaces. 5,12 In the literature in the case of iodine electrolyte, the visual change of the electrolyte colour has actually been so clear that it has been used for tracking the progression of corrosion. 7 The cobalt electrolyte has a much more pale color compared to iodine electrolyte which makes the tracking of corrosion electrolyte color more difficult.…”

Section: Stability Of Counter Electrode Made On Ferritic Steelmentioning

confidence: 99%

“…11 In a previous study it was shown that cobalt complex electrolytes are not completely non-corrosive but instability was seen in the case of several metals including copper, zinc and aluminum. 12 In that study the cheapest metal that was as stable as TCO glass was stainless steel (StS) 304. 12 StS 304 is one of the cheapest nickel containing 4 stainless steels and it has been estimated to be 10-60 % cheaper than glass with TCO coating of fluorine doped tin oxide (FTO).…”

mentioning

confidence: 99%

“…12 In that study the cheapest metal that was as stable as TCO glass was stainless steel (StS) 304. 12 StS 304 is one of the cheapest nickel containing 4 stainless steels and it has been estimated to be 10-60 % cheaper than glass with TCO coating of fluorine doped tin oxide (FTO). 1,13 In this contribution we aim to further significant cost reductions by applying a cheap ferritic stainless steel.…”

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confidence: 99%

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Low Cost Ferritic Stainless Steel in Dye Sensitized Solar Cells with Cobalt Complex Electrolyte

Miettunen¹,

Jouttijärvi²,

Jiang³

et al. 2014

J. Electrochem. Soc.

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Cheap ferritic stainless steel is applied here as the counter electrode substrate in dye sensitized solar cells with cobalt complex electrolyte. A 5.0 % efficiency was reached with these type of cells which is more than 2.5 times higher compared to previously reported devices with metal counter electrode and cobalt complex electrolyte. The electrochemical impedance spectra analysis showed that the best cells with the ferritic steel counter electrode had as low charge transfer resistance (3.6 Ωcm 2 ) as the reference glass cells with the same electrolyte. While in previous studies many metals have corroded in the cobalt complex electrolyte, the stability analysis including scanning electron microscope imaging of the aged electrodes suggested that the ferritic stainless steel substrates did not corrode in the electrolyte. Hence ferritic stainless steel appears as a possible alternative counter electrode in dye solar cells with cobalt electrolyte in terms of cost, performance and stability.

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Insights into corrosion in dye solar cells

Miettunen

Etula

Saukkonen

et al. 2014

Progress in Photovoltaics

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The main issue in using low cost metals in dye solar cells is the corrosion caused by the liquid electrolyte. Contrary to typical applications of metals, the adverse effects of corrosion in dye solar cells are related to irreversible depletion of charge carriers from the electrolyte rather than consumption of the metal itself. It is calculated that the penetration rate due to corrosion should not exceed 10 -4 mpy (a couple of nanometers per year) to ensure device lifetime longer than one year. This is 10000 times slower rate than what is considered to be a general benchmark value for very low corrosion rate in the field of corrosion science, and has a major effect on how corrosion should be investigated in the case of dye solar cells. Different methods, their applicability and limitations to investigate corrosion in dye solar cells are evaluated here. The issue with most techniques is that they can detect metals that are clearly corroding, but they have significant limitations in proving a metal stable. Our investigation shows that the most reliable information on corrosion is obtained from complete dye solar cells that are exposed to working conditions. A combination of color analysis of the electrolyte to such measurement is proposed as a means to extrapolate future performance of the cells and estimate potential lifetimes of the dye solar cells in regards to corrosion.

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Do Counter Electrodes on Metal Substrates Work with Cobalt Complex Based Electrolyte in Dye Sensitized Solar Cells?

Cited by 33 publications

References 22 publications

The Effect of Electrolyte Purification on the Performance and Long-Term Stability of Dye-Sensitized Solar Cells

The Effect of Electrolyte Purification on the Performance and Long-Term Stability of Dye-Sensitized Solar Cells

Low Cost Ferritic Stainless Steel in Dye Sensitized Solar Cells with Cobalt Complex Electrolyte

Insights into corrosion in dye solar cells

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