Influence of Coating a TiO₂ Electrode with DN-F05 and DN-F05-Ag on the Photovoltaic Performance of DSSC Solar Cells

Round 1

Reviewer 1 Report (New Reviewer)

In this paper the author mainly focused on working electrodes that used dye DN-F05 and the Ag ion in hybrid dye DN-F05 as a sensitizer and the Ag into the dye DN-F05 and the highest efficiency magnitude is 5.33% in DSSCs. The author claims that the addition of Ag will increase electron transport as evidenced by the increased efficiency (5.33%).  

The novelty of the discussion is missing. A detailed comparison is needed, and the current state of the paper is not enough for publication. I did not have a good impression of this paper. The author didn't explain/provide a detailed discussion. Many sentences have not been clearly explained.  But the topic is interesting for the referee Therefore, I recommend publication only after major revisions.

If the author is interested in revising this paper, clarify the following questions.

 1) The abstract in this article is not so exciting; the author needs to rewrite the abstract and needs to include the motivation and necessity of this research.

2) I think that the introduction is not sufficient. So, the author needs to discuss/include more background on previous results and why the author used “Ag” for these studies.

3) Page NO.1, Line 41-42: the author needs to include what type of TiO₂ is used.

4) Page No.2, lines 47-48: the author has written “high efficiency---. I think that the author needs to include the efficiency of D35 dyes in different papers.

5) The author needs to include the appropriate working principal figure in the introduction for better understanding.

6) Why the author has chosen DN-F05 dye mainly, needs to include valid explanation in this paper.

7) Page 2: Has the author measured the thickness of TiO2 on FTO? Need to include in the manuscript.

8) Which electrolyte used for this study, needs to include the composition of the electrolyte?

9) In the result and discussion, the author needs to include a comparison of the present work with the previous work. And needs to explain the importance of the present work. 

10) I think that the author needs to include IPCE spectra, Impedance spectra for better understanding. These analyses give more conclusions of this work. So, a detailed investigation is needed.  

11) The author has measured the amount of dye absorbed on TiO2 film, Please include it in this manuscript.

12) In the discussion, the author needs to include a comparison of work (effects, advantages, importance of molecular design, disadvantages). And needs to explain the importance of the present work. 

13) Language of the manuscript should be checked in detail. It is far from academic writing language. Get help from professionals or natives if necessary.

14) Page NO:2, Line 46-55 (total para): references 21 and 22 cited papers have shown that the DN-F05 efficiency is ~6.8-7%. But the author’s results have not improved. So, what is the major importance of these studies? Need to include detailed discussion.

 

15) All figures in this manuscript are not good/in appearance. It is one of the drawbacks of this manuscript presentation. The author should change all the figure presentations and show them clearly.

The language of the manuscript should be checked in detail. It is far from academic writing language. Get help from professionals or natives if necessary.

Author Response

Dear Reviewer 1,

Here I attached the document of revision

Thank you

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

Comments to the authors

The manuscript entitled “The influence of dye DN-F05 and DN-F05-Ag as a thin film TiO2 immersion toward increasing of photocatalyst activity and crystal size” has been submitted by the author. However, there are still major concerns that need to be addressed before publication. Therefore, I recommend this work could be published after the major revision.

1. The introduction should be elaborated with stat of art.
2. The study focuses on DSSC, a field that was once at the forefront of solar cell research approximately 15 - 20 years ago. Since then, perovskite-based solar cells have emerged as a dominant force in the field. However, the manuscript does not acknowledge this recent advancement, although it is crucial to consider these developments when furthering the field of DSSC.

3. The manuscript lacks a comprehensive justification for the utilization of silver (Ag) and fails to elucidate the authors' motivation for selecting this material. The role of Ag is also inadequately explained. Furthermore, the manuscript overall lacks substantial discussion and elaboration throughout its entirety.
4. Throughout the manuscript, there is a notable lack of in-depth discussion and analysis. The authors should provide a more detailed interpretation of the experimental results and relate them to previous studies. Additionally, they should discuss the limitations and potential sources of error, as well as propose potential strategies for future improvements or optimizations. Enhancing the discussion section will enrich the scientific contribution of the study.

5. Is there any effect of surface plasmon resonance (SPR) to dye sensitized solar cell efficiency due to Ag?
6. The author should provide the TEM analysis.
7. Fig. 5 the SEM magnification is not clear. Authors should provide neat and clear figures with labels.
8. Revised the conclusion part and write their most highlighted point in this paper.
9. English should be checked through the whole manuscript because there are many spelling and grammatical errors in the paper.

The manuscript entitled “The influence of dye DN-F05 and DN-F05-Ag as a thin film TiO2 immersion toward increasing of photocatalyst activity and crystal size” has been submitted by the author. However, there are still major concerns that need to be addressed before publication. Therefore, I recommend this work could be published after the major revision.

Author Response

Dear Reviewer 2,

Here I attached the document of revision

Thank you

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

Please see the attached file.

Comments for author File: Comments.pdf

Please see the attached file.

Author Response

Dear Reviewer 3,

Here I attached the document of revision

Thank you

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (New Reviewer)

Thank you to the author for addressing all the raised comments from reviewers. The authors have carried out the modifications and the corrections to the queries raised and indeed have provided more information in the revised version. Therefore, I recommend this manuscript for publication in Applied Sciences as it is without further modifications.

 Minor editing of the English language required

Author Response

Dear Reviewer 1,

Here We attach the revised document

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

Authors modified the paper according to my comments. Now the paper should be accepted

Authors modified the paper according to my comments. Now the paper should be accepted

Author Response

Dear reviewer 2, 

Thank you for comment 

Reviewer 3 Report (New Reviewer)

Figure 1. DSSC Schematic diagram illustrating.

This is the figure caption for Fig. 1, it is not even a complete sentence. As such it does not make any sense.  Please explain what the figure is about and rewrite the figure captions.

   I am happy with the scientific contents but the language requires very serious editing. The editorial office may take the responsibility in editing the English then it may be published.

I do not not need to see it again.

 

   I am happy with the scientific contents but the language requires very serious editing. The editorial office may take the responsibility in editing the English then it may be published.

I do not not need to see it again.

 

Author Response

Dear Reviewer 3, 

Here I attach the revised document

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The manuscript presents a comparative study on the effects of Ag added in DN-F05 on band gap and photovoltaic performance.  It can’t meet the high criteria of Materials in current format. Major revision is suggested.

1. There is no introduction or discussion on Fig. 1a in the manuscript.
2. Please make the “Figure” and “Fig” consistent in the manuscript.
3. The figure size of Figure 1(a) and (b) is different. Please adjust the size.
4. For the XRD result, the relative peak density of TiO₂ and FTO is slight different between the TiO₂:DN-F05 and TiO₂:DN-F05:Ag, such as the 2Theta at around 46 and 52 degree. How does the author explain this difference?
5. In the SEM part, the author showed the TiO₂ morphology and mentioned that “there are uneven spherical lumps”, but the SEM image in Figure 5(a) is quite hard to see details.
6. In the XRD part, the author mentions “The appearance of these peaks indicates that the presence of Ag is stable on the crystal surface without disturbing the crystal structure of TiO₂”, but in the SEM part, the author wrote “It can be seen that is a significant structural change due to the addition of Ag solution.” Those two parts are quite confusing. Could the author revise it?
7. What’s the film thickness of three samples? Could the author add details for the band gap calculation?
8. For the photovoltaic performance, did the author compare the result with other reported results of TiO₂ anatase phase?

Author Response

Author's Reply to the Review Report (Reviewer 1)

Comments and Suggestions for Authors

The manuscript presents a comparative study on the effects of Ag added in DN-F05 on band gap and photovoltaic performance.  It can’t meet the high criteria of Materials in current format. Major revision is suggested.

1. There is no introduction or discussion on Fig. 1a in the manuscript.

Answer: We've fixed it, the explanation for Fig.1a is in the introduction and We've marked it with a blue line (line 49).

which commonly called dye D35 (Fig.1a) with …………………….

1. Please make the “Figure” and “Fig” consistent in the manuscript.

Answer: We've replaced it consistently with Fig.

1. The figure size of Figure 1(a) and (b) is different. Please adjust the size.

Answer: We already fix it

1. For the XRD result, the relative peak density of TiO₂ and FTO is slight different between the TiO₂:DN-F05 and TiO₂:DN-F05:Ag, such as the 2Theta at around 46 and 52 degree. How does the author explain this difference?

Answer: Actually there is almost no difference for the peak, it's just that because TiO2:DN-F05:Ag has a very large Ag concentration, this causes the TiO2 peak to be less clear, this is because the TiO2 layer is covered by an Ag layer. This event is also associated with different changes in FESEM (Fig.5c) results when there is a concentration of Ag and before it is present.

1. In the SEM part, the author showed the TiO₂ morphology and mentioned that “there are uneven spherical lumps”, but the SEM image in Figure 5(a) is quite hard to see details.

Answer: We have fixed it by providing an image of the TiO2 surface at a magnification of 30,000X, from the image it can be seen clearly that there are lumps.

1. In the XRD part, the author mentions “The appearance of these peaks indicates that the presence of Ag is stable on the crystal surface without disturbing the crystal structure of TiO₂”, but in the SEM part, the author wrote “It can be seen that is a significant structural change due to the addition of Ag solution.” Those two parts are quite confusing. Could the author revise it?

Answer: In this sentence “The appearance of these peaks indicates that the presence of Ag is stable on the crystal surface without disturbing the crystal structure of TiO₂”, The author just wants to explain that the peak detected is a stable peak, even though there is only one peak. This is because the other Ag peaks decrease in intensity due to aggregation.

1. What’s the film thickness of three samples? Could the author add details for the band gap calculation?

Answer:

1. FTO:TiO₂ = ~300 nm
2. FTO:TiO₂:DN-F05 = it is possible not to get too thick, because the dye absorbs into the pores of the TiO₂.
3. FTO:TiO₂:DN-F05:Ag = for this sample the author did not measure the thickness of the sample after the addition of Ag.

 

1. For the photovoltaic performance, did the author compare the result with other reported results of TiO₂ anatase phase?

Answer: Yes, We did. We used some previous research that related with dye DN-F05.

1. Ellis H, Eriksson S K, Feldt S M, Gabrielsson E, Lohse P W, Lindblad R, Sun L, Rensmo H, Boschloo G and Hagfeldt A 2013 Linker unit modification of triphenylamine-based organic dyes for efficient cobalt mediated dye-sensitized solar cells Phys. Chem. C 117 21029–36
2. Supriyanto, A., Saputri, D. G., Ahmad, M. K. B., Ramelan, A. H., & Ramadhani, F. (2021). Significant efficiency improvement of TiO2: LEG4-Ag layer dye sensitized solar cells by incorporating small concentration of Ag. Optik, 231, 166429.
3. Gabrielsson E, Ellis H, Feldt S, Tian H, Boschloo G, Hagfeldt A and Sun L 2013 Convergent/divergent synthesis of a linker-varied series of dyes for dye-sensitized solar cells based on the D35 donor Energy Mater. 3 1647–56

Author Response File: Author Response.docx

Reviewer 2 Report

In this manuscript, the authors used DN-F05 and DN-F05-Ag to enhance the photocatalyst activity of TiO₂ films prepared by a spin coating method. Several techniques are used to characterize these samples such as XRD, SEM, J-V characteristics. However, some results analysis needs to be further improved. Some comments are as follows.

 

1. Line 137, the phase/structure of silver … instead of shape. Face centered cubic instead of Face Center Cubic, fcc instead of FCC.
2. Line 142-143, there are multiple diffraction peaks belonging to anatase shown in figure 4a for the sample “pure TiO2”. I am not sure why the authors claimed that only one clearly visible anatase peak?
3. Line 144, what is the layer in the reference, what is the thickness of TiO2 layer on the glass substrate?
4. Line 145, the two “new peaks” are not indicated by the XRD pdf card of FTO as shown in figure 4a. How do the authors believe that they are from FTO instead of other potential TiO2 phases?
5. Line 158, no peak at 37.810 is clearly seen as indicated by the purple line in figure 4b. Moreover, there are so many peaks that overlap between ~37 to ~ 39 degrees. How can the authors make sure a peak belongs to Ag, not others? Additionally, a phase could not be identified just by a single diffraction peak. Thus, I do not think the XRD pattern shown in figure 4b can demonstrate the existence of Ag metal in the sample TiO2:DN-F05:Ag.
6. Why does the intensity of the main diffraction peak of the sample with DN-F05 and DN-F05:Ag decrease significantly compared to the pure:TiO2, especially for the sample TiO2:DN-F05:Ag?
7. Line 161 to 163, what is the temperature when you put the TiO2 spin-coated film into the DN-F05:Ag solutions? Is there any post-annealing for the sample TiO2:DN-F05:Ag? How to understand the Ag interstitial in TiO2 crystals?
8. Line 164, what is the meaning of “in Figure 4b looks thicker”? Do you mean the thickness of the sample is thicker than pure TiO2? You should make it clear. Why a thicker sample leads to the removal of some diffraction peaks of anatase TiO2 and FTO (line 165).
9. In table 1, Why the diffraction angles used to estimate the crystallite sizes of these three samples are different? What are the criteria to choose these angels to estimate the crystallite size? Are these crystallite sizes all for TiO2?
10. Line 183, why Ag can damage the TiO2 layer and increase the grain size of the TiO2 layer? More details, references, or evidence are needed.
11. Line 193, I do not think readers can see uneven spherical lumps in figure 5a. Authors can label or highlight the so-called “spherical lumps” in the figure.
12. Line 194-195, what are the small balls attached to the FTO layer? FTO is the substrate, right? Also, I could not see the “small balls” and do not understand why they can demonstrate the existence of a TiO2 layer on FTO.
13. Line 198-199, in Figures 5b and 5c, how to tell the significant structural changes due to the addition of Ag? The grain size of these three samples is all smaller than 100 nm but the resolution of the FESEM images is not good enough to tell the structural damages.
14. 8 and Table 3, need to add the curve of the pure TiO2 sample as an experimental control.
15. Line 270, crystal size is a typo.
16. What is the concentration effect of DN-F05 and Ag on the photocatalyst activity?

 

 

 

 

 

 

 

 

Author Response

Comments and Suggestions for Authors 2

In this manuscript, the authors used DN-F05 and DN-F05-Ag to enhance the photocatalyst activity of TiO₂ films prepared by a spin coating method. Several techniques are used to characterize these samples such as XRD, SEM, J-V characteristics. However, some results analysis needs to be further improved. Some comments are as follows.

 

1. Line 137, the phase/structure of silver … instead of shape. Face centered cubic instead of Face Center Cubic, fcc instead of FCC.

Answer: We've replaced it and mark by blue line.

2. Line 142-143, there are multiple diffraction peaks belonging to anatase shown in figure 4a for the sample “pure TiO2”. I am not sure why the authors claimed that only one clearly visible anatase peak?

Answer: It is true that in the pure "TiO2" sample there are many clear peaks, but when explaining the sentence, the author only focuses on the 37,805 nm point, where there are 3 peaks that should be detected but which shows clarity only at an angle of 37,805 nm.

3. Line 144, what is the layer in the reference, what is the thickness of TiO2 layer on the glass substrate?

Answer: “what is the layer in the reference” means reference by “JCPDS no. 21-1272” in Fig.4a are marked in blue (anatase standard). While the thickness of TiO2 layer is ~300 nm.

(We have added this reason to the paper marked by blue line)

4. Line 145, the two “new peaks” are not indicated by the XRD pdf card of FTO as shown in figure 4a. How do the authors believe that they are from FTO instead of other potential TiO2 phases?

Answer: The author believes that the appearance of these 2 peaks is FTO glass detected during testing, because the first sample is FTO glass coated with TiO₂ only, because TiO₂ has been detected perfectly, it is possible that the two new peaks are FTO glass.

5. Line 158, no peak at 37.810 is clearly seen as indicated by the purple line in figure 4b. Moreover, there are so many peaks that overlap between ~37 to ~ 39 degrees. How can the authors make sure a peak belongs to Ag, not others? Additionally, a phase could not be identified just by a single diffraction peak. Thus, I do not think the XRD pattern shown in figure 4b can demonstrate the existence of Ag metal in the sample TiO2:DN-F05:Ag.

Answer: Firstly, The clear peak appears at 37.810^◦ (111) that indicated as the peak of Ag based on JCPDS database no. 04-0783.

Secondly, the appearance of these peaks indicates that the presence of Ag is overlapping, thereby removing some of the peaks of TiO₂ anatase and FTO, this allows for aggregation of the mixed dye solution and Ag. So that’s why the authors believe that peak appear at 37.810^◦ is Ag.

6. Why does the intensity of the main diffraction peak of the sample with DN-F05 and DN-F05:Ag decrease significantly compared to the pure:TiO2, especially for the sample TiO2:DN-F05:Ag?

Answer: From Fig. 4a. it can be seen that the dye DN-F05 was not detected, this was because the dye DN-F05 was amorphous. The presence of DN-F05 dye helps the excitation of electrons, this can be proven from Fig. 4a, where TiO₂-DN-F05 has a higher intensity than pure TiO₂.

As for the concentration of TiO₂:DN-F05:Ag (Fig.4b), some Ag peaks decrease in intensity and are not visible, this is because the concentration of Ag that is too large can replace atoms in the TiO₂ molecule (Ag contamination in the TiO₂ crystal lattice either through the interstitial ) resulting in atomic defects.

7. Line 161 to 163, what is the temperature when you put the TiO2 spin-coated film into the DN-F05:Ag solutions? Is there any post-annealing for the sample TiO₂:DN-F05:Ag? How to understand the Ag interstitial in TiO2 crystals?

Answer: When we do the coating, we use room temperature of 19^o C. After coated TiO₂ on FTO glass, the FTO glass is heated on a hot plate at 40^o C. After drying, the sample is post-annealed at 450^o C for 30 minutes.

8. Line 164, what is the meaning of “in Figure 4b looks thicker”? Do you mean the thickness of the sample is thicker than pure TiO2? You should make it clear. Why a thicker sample leads to the removal of some diffraction peaks of anatase TiO2 and FTO (line 165).

Answer: The sample is thicker than TiO₂:DN-F05:Ag. The reason why thicker sample leads to the removal of some diffraction peaks of anatase TiO2 and FTO is:

Several other Ag peaks are decreasing in intensity and are not visible, this is because too large Ag concentrations can replace atoms in TiO2 molecules (Ag contamination in the TiO2 crystal lattice either through interstitials) resulting in atomic defects. This incident is the main reason that the addition of too much Ag concentration will reduce the performance of DSSC.

We already added this reason to the paper marked by blue line.

9. In table 1, Why the diffraction angles used to estimate the crystallite sizes of these three samples are different? What are the criteria to choose these angels to estimate the crystallite size? Are these crystallite sizes all for TiO2?

Answer: Data collection on each sample is based on the greatest intensity value obtained. Due to the large number of data, we only take the 2 largest intensities, for crystal size calculations we use all data calculations.

10. Line 183, why Ag can damage the TiO2 layer and increase the grain size of the TiO2 layer? More details, references, or evidence are needed.

Answer: The addition of too large a concentration of Ag can damage the crystal structure. This is because too much Ag concentration will cover the top surface of the layer which then tries to enter the semiconductor pores and replaces the position of the TiO₂ molecule, resulting in atomic defects / atomic defects.

We already added this reason to the paper marked by blue line.

11. Line 193, I do not think readers can see uneven spherical lumps in figure 5a. Authors can label or highlight the so-called “spherical lumps” in the figure.

Answer: We already fix it, We added an FTO-coated by TiO₂ image at 30,000X magnification (Fig.5a) to make it easier for readers to understand the meaning of the word "lumps".

12. Line 194-195, what are the small balls attached to the FTO layer? FTO is the substrate, right? Also, I could not see the “small balls” and do not understand why they can demonstrate the existence of a TiO2 layer on FTO.

Answer: On line 194-195, We explained that the small ball is in the FTO which has TiO₂ on it, we have corrected our writing with a blue mark. In addition, we also added an FTO-coated by TiO₂ image at 30,000X magnification (Fig.5a).

13. Line 198-199, in Figures 5b and 5c, how to tell the significant structural changes due to the addition of Ag? The grain size of these three samples is all smaller than 100 nm but the resolution of the FESEM images is not good enough to tell the structural damages.

Answer: To see the presence of structural changes due to the addition of Ag, it can be seen from Fig. 5b and 5c. Before the addition of Ag (Fig. 5b) it can be seen that there are small balls around the nanorod-shaped structure, but after the addition of Ag (Fig. 5c) it can be seen that the small balls are deformed into a rough surface. It is possible that the addition of large Ag causes atomic defects and aggregation.

14. 8 and Table 3, need to add the curve of the pure TiO2 sample as an experimental control.

Answer: We did not test for pure TiO2, because we wanted to see the performance of the dye during electron capture, so samples without dye were not tested for J-V.

15. Line 270, crystal size is a typo.

Answer: We already fix it.

16. What is the concentration effect of DN-F05 and Ag on the photocatalyst activity?

Answer: The addition of Ag into the DN-F05 dye will increase electron transport, thereby helping to increase energy harvesting. This proved that the conductivity of TiO2 increased with the addition of Ag, Therefore, the addition of Ag will increase the efficiency value.

(We have added this reason to the paper marked by blue line)

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Thank you for replying the comments. I recommend to publish the manuscript in current form.

Reviewer 2 Report

The authors addressed the comments. It is ok for publication.