Cyanobacterial Pigments as Natural Photosensitizers for Dye-Sensitized Solar Cells
and María Fernanda Cerdá 1,*Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn the manuscript, the authors evaluated the properties of the 11 pigments from three filamentous freshwater cyanobacterial strains were evaluated as suitable natural compounds to be applied in dye-sensitized solar cells. I think it could be considered to be published in Photochem after the following major revisions are made.
1. How were the extracts of PCCC_E5 in the lipidic pigments obtained? There seemed to be something information in the parts of Materials and Methods.
2. The composition and content of the pigments from three cyanobacterial strains should be determined. Is there any difference at all? Whether the content of the pigments on the power conversion efficiency? The quantitative analysis of the pigments is recommended to be characterized by HPLC or LC-MS.
3. With an efficiency of 0.127 %, the authors’ results are higher 14 than those previously reported using similar structured compounds from natural sources as algae and cyanobacteria, among others. What could cause this?
4. Why were the three cyanobacterial strains were acclimated in subsequent light intensity increments? How did the light intensity affect the cyanobacterial strains? The growth curve and the activity should be determined.
5. Cyclic voltammetric profiles for D3267 and E5 should be supplemented in Figure 2.
6. In Figure 4, Nyquist plots should be measured for the more efficient cells sensitized with the dyes from D3267.
7. Normalized visible absorption and emission spectra for the pigments from D3267 and E5 should be added.
Comments on the Quality of English LanguageMinor editing of English language required.
Author Response
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Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsDear Authors,
This paper focuses on the characterization and application of naturally derived dyes as light absorbers in DSSC cells. I fully understand the research direction regarding the use of natural extracted dyes. However, I have my doubts about the validity of publishing research results if solar cell efficiencies are so low. In addition, I have some questions and comments on the manuscript:
1. What solvent was used to prepare the photoanodes? This information should be added in section 2.3.
2. The scale in Figure 1b starts at about 350 nm even though the spectrum is recorded at 400 nm, why?
3. It is also worthwhile, in my opinion, to present absorption spectra in the UV-Vis range for photoanodes with anchored molecules of the studied dyes.
4. Also, isn't it worth thinking about modifying solar cells to improve performance to indicate that it is possible for PCE values to be higher? The results obtained are very low, I am mainly concerned with Jsc and PCE, is there then a point in sourcing such compounds?
5. It is also worth quoting the photovoltaic performance of cells prepared under identical conditions containing a commercial dye, e.g. N719, which often acts as a reference in the literature.
6. Have there been studies of the surface of photoanodes with anchored dyes? Have changes in morphology been observed after the dye adsorption process?
7. It would also be useful to show the current-voltage curves for dark current so that the photovoltaic effect that occurs can be confirmed.
Comments on the Quality of English Language
Minor editing of English language required.
Author Response
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Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript is ready for publication. I have not only been highly impressed with how the authors had addressed all of my points but also how they dealtwith the other reviewers' points.
Author Response
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Reviewer 2 Report
Comments and Suggestions for AuthorsDear Authors,
Thank you for preparing answers to my questions and comments, I think the work is suitable for presentation, below are some comments that do not affect the evaluation of the article.
1. With reference to question 1 of the previous review, I was concerned with exactly what the dyes were dissolved in when immersed in their FTO/TiO2 solutions. As I understand it these were solutions in EtOH.
2. With reference to question 4, I obviously agree with the authors that it is important to study natural dyes with a view to using them as light absorbers in DSSCs, but I wonder whether it is possible, and to what extent, to improve the performance of such a device by, for example, using blocking layers, possibly coadsorbents if there is aggregation, scattering layers, etc. It seems to me that it would be worthwhile to try to develop this topic in future studies.
3. It may be worthwhile to collaborate with centres that have, for example, AFM microscopes, as I know from experience that even determining roughness gives interesting results.
Author Response
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