Optimizing a Simple Natural Dye Production Method for Dye-Sensitized Solar Cells: Examples for Betalain (Bougainvillea and Beetroot Extracts) and Anthocyanin Dyes
Round 1
Reviewer 1 Report
The author describes a method for extraction of natural sensitizers for DSSCs. Different parameters have been analyzed and compared. The procedure, as well as the literature, have been sufficiently described and the material have been tested in DSSCs. The resulting efficiency obtained for the best system is something around 0.5%, claimed as one of the highest value obtained using natural sensitizers. Even with this result, I believe that the manuscript is not interesting by the point of view of the photovoltaic devices but it can still be interesting by the chemical point of view considering the exhaustive work done in the analysis of all the system. I suggest to change the target of the manuscript avoiding or minimizing the photovoltaic part (also the reference cell with N719 showed a very low efficiency, not sufficient to ensure a good comparison) and focusing on the chemical one.
Author Response
We would like to thank the referee's comments and suggestions, which have allowed us to improve the quality of our manuscript. We have corrected all the deficiencies mentioned by reviewer as detailed below.
- English language and style
In the revised version of the manuscript, writing tools have been used to improve English language, we have corrected grammar and spelling mistakes, and also the document has been proofread by an appropriate party prior to re-submission.
Detailed changes in the revised manuscript are highlighted by the “track changes” function in MS Word.
- “to change the target of the manuscript avoiding or minimizing the photovoltaic part”
We have made major changes in the revised version of the manuscript, mainly in the Featured Application, the Abstract, the Introduction and the Conclusions sections. The references have also been changed. The manuscript has been re-organized, focusing on the work conducted on the analysis of the system and minimizing the photo-voltaic part, mentioning the NDSSCs results just as an example of the use of the natural colorants studied (last subsection 3.3 previous to the conclusions).
We have not eliminated completely the photo-voltaic part because the manuscript was submitted to section: 'Materials, Dyes for Use in Photodynamic Therapy (PDT) and Dye Sensitized Solar Cells (DSSCs)' and also because our group has been working on DSSCs for several years so we decided to show some of our results as an example of the use of dyes in these devices.
- “the reference cell with N719 showed a very low efficiency”
As the aim of this work is the study of dyes, their application as DSSC's sensitizers is just an example of their multiple uses. To show it, we have fabricated solar cells following a simple and economical procedure, not optimized to give the highest efficiency, which would need more elaborate methods (for example ref. 40 in this manuscript). The N719 cell is also fabricated with this simple procedure, to compare with the NDSSCs. A short paragraph explaining this fact has been included (lines 503-505 in the revised manuscript).
When the aim is to optimize the whole to maximize the efficiency, other parameters are involved, from the surfactant used in paste preparation to film thickness, and so we can obtain higher cell efficiency (i.e. 8.9±0.9 % in Maldonado-Valdivia et al. work, reference 38 in this manuscript)
Reviewer 2 Report
This paper summarizes much of the published results on the use of natural dyes on dye-sensitized solar cells and add some of the authors results. They report on the different extraction methods, characterization of the dyes extract and application on DSSC. They propose a unified protocol to compare the results and enhance the dye potential. The results are honestly compared with the best synthetic dyes showing the advantages and limitation of the use of these natural dyes extracts including their lower efficiency and stability.
The work is very complete and can be very useful as a review on the use of these dyes rather than showing a great novelty. It is carefully written with minor English mistakes.
I recommend its publication without changes
Author Response
We want to thank referee's comments and suggestions, which have allowed us to improve the quality of our manuscript. We have corrected the deficiencies mentioned by reviewer as detailed below.
- English language and style
In the revised version of the manuscript, writing tools have been used to improve English language, we have corrected grammar and spelling mistakes, and also the document has been proofread by an appropriate party prior to re-submission. Detailed changes in the revised manuscript are highlighted by the “Track Changes” MS Word function.
Round 2
Reviewer 1 Report
I agree with the revisions.
