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

Abstract

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...

Analysis of dye degradation products and assessment of the dye purity in dye-sensitized solar cells

“…The dye was successfully extracted and analyzed from aged solar cells (see cell preparation in the Experimental section) containing Z907 and N719 . The LC/MS results were similar to those obtained from the parent dye analysis with identifiable peaks from the dyes and their degradation products for both Z907 (data not shown) and N719 (reported elsewhere) . Several of the previously reported degradation products, most notably [RuL 2 (NCS)(3‐MPN)] and [RuL 2 (NCS)(NMBI)], were observed.…”

“…The intact cells that were utilized for optimization of the dye extraction method only were prepared and aged according to a method described in the literature . The cells were prepared with two different dye solutions consisting of either 0.3 mM Z907 or 0.3 mM N719 in acetonitrile and tert ‐butanol (1:1).…”

Air Processed Inkjet Infiltrated Carbon Based Printed Perovskite Solar Cells with High Stability and Reproducibility

“…The yellow color could result from lead iodide forming to the edge areas of the cell. Hence we also investigated any possible change in the active area under the carbon with our established camera imaging technique (which we have demonstrated in earlier reports for monitoring the degradation in DSSCs) as the changes were so minor that it was difficult to analyze them by the eye (Figure c,d). The aged cells were found lighter than the fresh ones, i.e., the cell materials had transformed also at the interior of the cell during the aging even though it was not apparent by the eye or by the changes in the efficiency of the cells (Figure S4, Supporting Information).…”

Long term stability of air processed inkjet infiltrated carbon-based printed perovskite solar cells under intense ultra-violet light soaking

“…21 These promising stability results encouraged us to investigate further the stability of these air processed inkjet inltrated CPSCs under a new stress i.e. ultra-violet (UV) light which has been identied as one of the key issues for the long term stability of other types of PV systems such as dye-sensitized solar cells (DSSCs), 22,23 and has raised concerns also in the eld of perovskite solar cells. 8,24,25 Hence one batch of inkjet inltrated CPSCs (similar to the cells fabricated in ref.…”