Annealing Effect on One Step Electrodeposited CuSbSe₂ Thin Films

Round 1

Reviewer 1 Report

Authors have reported the annealing effect on the electrodeposited CuSbSe3 thin films. The work needs to be improved and could be considered for publication after a major revision. Reviewer has the following comments and suggestions to be addressed.

1. Line 97-99, accumulation time, objective with spot size and penetration depth should be provided.
2. What was the thickness of the as deposited film? And how it behaves with the annealing temperature?
3. Authors should provide an average grain size histogram in order to better understand the surface morphology?
4. No elemental map of oxygen until 250 C. Any specific reason.
5. The atomic % of oxygen first increases and then decreases at 350C and again increase. Explain the reason behind such a progress. It may be coming out of FTO substrate.
6. As the initial as deposited samples shows the presence of Sb2O3, it means the sample is already oxidised with the presence of oxygen from the chemical solution. While at 350 C, there is still some oxygen content available, where is it coming from, as in the conclusion it has been mentioned that films annealed at 350 C are more feasible.
7. However, at 300 C, there is formation of polycrystalline film starts. What is the physical-chemical mechanism occurring?
8. What is the reason behind the decrease- increase- decrease size of crystals upto 350 C? Please explain it, otherwise the sentence from line 125-134, are just a simple observation of SEM images. No scientific information being added.
9. Line 150-151, layer is transparent for 500 C, while in the optical transmission shows most transmission of 30% for film annealed at 450 C. Specify the reason?
10. XRD of the as deposited film is not presented. Specify the reason.
11. Line 169, if there is a presence of Sb2O3 in the prepared film, presence of Sb2O3 degrade the performance of the solar cell and restrict the use of this type of materials from application point of view. Please specify in detail as well as in the integrate this in the revised manuscript.
12. Raman spectrum of the as deposited film is missing, as it could be the starting point in order to understand the annealing behaviour of the film. Please include the as deposited Raman spectrum in the Figure 5. As in this type of system when annealed starts showing Sb2O3 phase at about 200 C. Cite [ Phys. Chem. C 2021, 125, 36, 19858–19865].
13. The employed laser power was 30mW with 532nm laser, however it has been recently reported at about 2.5mW with 633nm laser, this type of system starts causes anharmonic effects in solids, evidenced by a broadening and a peak red shift of the Raman bands, and simultaneously, under high-power or prolonged laser irradiation, structural transitions and crystalline changes may occur due to long-range ordering, as well as local or macroscopic ordering, cite [ Phys. Chem. C 2021, 125, 36, 19858–19865]. So the Raman measurements with such a high laser power could not be from the pristine thin film.
14. Line 234, Raman should be in capital letter.
15. Authors should add few sentences on the crystal orientation and its potential impact on the performance on the solar cells, as no information is presented while it has been stated in abstract and conclusion. Can refer to the following article [Solar Energy Materials & Solar Cells (2019), 197].

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper presents an interesting method to electrodeposit CuSbSe₂ thin films in a single step. The influence of annealing temperature on the structural, morphological, compositional and optical characteristics of CuSbSe₂ thin films are detailed studied. The results show the growth of single-phase CuSbSe₂ thin films is feasible at a temperature of 350 °C. This paper is well structured, but it cannot be accepted in its present version due to some key information is lacking and some contents need to be further explained. 

1. Why do the big agglomerates form at 450℃ but not form at 500℃?
2. Why does the Cu/Sb ratio decrease when the temperature increase from 450℃ to 500℃?
3. Is there any results that can support the conclusion of “the formation of Sb₂O₃ secondary phases could be avoided by…” in lines 281-283?
4. The description in line 106 is unclear. What is the object of “competitive absorption”?
5. Which result supports the conclusion of “The deposition potential of -0.40 V/SCE ...” in lines 118-120?
6. The authors should check the grammar mistakes, such as “many less Sb₂O₃ crystals” in line 133.

Author Response

Dear Editor and Reviewers, 

Thank you for giving us the opportunity to submit a revised draft of the manuscript “Annealing effect on one step electrodeposited CuSbSe₂ thin films” for publication in the Journal of MDPI Coatings. We appreciate the time and effort that you and the reviewers dedicated to providing feedback on our manuscript and are grateful for the insightful comments on and valuable improvements to our paper. Each point has been considered carefully and the manuscript has been revised accordingly. The following are detailed response to each of the comments.

Reviewer #2:

Thank you for the valuable comments.

Point 1: Why do the big agglomerates form at 450℃ but not form at 500℃?

Response 1: Thank you for pointing this out. Certainly, the growth process of CuSbSe₂ deposit under annealing temperature effect is very curious, in particular the shrinkage of the layer at 450°C and its diffusion at 500°C. However, Guo et al [23] (in the manuscript) explain that as the annealing temperature of CuSbSe₂ approaches melting (480°C), the grain size gradually increases and the small particles cluster together to form large blocky particles. [line 172-177].

Point 2: Why does the Cu/Sb ratio decrease when the temperature increase from 450℃ to 500℃?

Response 2: from 400 to 500 °C, the Cu/Sb ratio was found to increase up to 3.86, suggesting that a part of the Sb might have been lost due to Sb₂Se₃ sublimation [line 181-182].

Point 3: Is there any results that can support the conclusion of “the formation of Sb2O3 secondary phases could be avoided by…” in lines 281-283?

Response 3: In the supporting information, we have added images (Figure S3) showing how chemical etching removes Sb2O3. Nevertheless, the removal of the Sb2O3 octahedra left holes, which cause a shunt effect. However, projects are underway to address this issue

Point 4: The description in line 106 is unclear. What is the object of “competitive absorption”?

Response 4: Thank you for pointing this out. In fact there is a typing error, it is "competitive adsorption". The adsorption process is considered to be a potential-dependent first step in the metal-ions reduction mechanism. The voltammogram of the Cu-Sb-Se solution (Figure 2) shows that the copper reduction peaks are hardly noticeable. This could be explained by the fact that there is a competition with the precursors of other species present in the solution to reach the adsorption sites on the substrate. This explanation corresponds to the references [14] [line 125-126]

Point 5: Which result supports the conclusion of “The deposition potential of -0.40 V/SCE ...” in lines 118-120?

Response 5: We have already done work to define the most suitable potential for CASe deposition, reference [16]. References [14] and [15] also support this result.

Point 6: The authors should check the grammar mistakes, such as “many less Sb2O3 crystals” in line 133

Response 6: Thank you for pointing this out. The “many less Sb2O3 crystals” has been corrected on line 159.

Author Response File: Author Response.pdf

Reviewer 3 Report

Remarks review: of manuscript entitled “ Annealing effect on one step electrodeposited CuSbSe2 thin films". The results is an excellent in this study, but It needs more work and revisions as listed in the following points:

1-Abstract and conclusion needs revision and must be included some numbers of the optimum results at best conditions.

2-Introduction: it’s very short needs expansion and explain the objective of this work in the last paragraph of the introduction.

3- All equations need references excepted chemical equations that beyond to the practical results of the authors .

4- In general all figures are need revision and clarification.

a- Fig.3,. SEM /EDS Morphological images need revision of the magnification bar not clear , also ,all images must have the same magnification for the purpose of comparison under different conditions. In addition to the pictures of EDS, they are very poor and unclear elements.

b-Fig4 :XRD patterns of the CuSbSe2 thin films  must be fixed the orientations(indexed planes ) on each peaks and more discussed it .

5-The language of the article has to be slightly revised. 

Author Response

Dear Editor and Reviewers, 

Thank you for giving us the opportunity to submit a revised draft of the manuscript “Annealing effect on one step electrodeposited CuSbSe₂ thin films” for publication in the Journal of MDPI Coatings. We appreciate the time and effort that you and the reviewers dedicated to providing feedback on our manuscript and are grateful for the insightful comments on and valuable improvements to our paper. Each point has been considered carefully and the manuscript has been revised accordingly. The following are detailed responses to each of the comments.

Reviewer #3:

Thank you for the  valuable comments.

Point 1: Abstract and conclusion need revision and must be included some numbers of the optimum results at best conditions.

Response 1: The manuscript has been carefully revised by the authors

Point 2: Introduction: it’s very short needs expansion and explains the objective of this work in the last paragraph of the introduction.

Response 2: As suggested by reviewer 3, a paragraph was added at the beginning of the introduction to explain the motivations [line 30-34] and a final one to explain the purpose [line 72-82].

Point 3: All equations need references excepted chemical equations that are beyond the practical results of the authors.

Response 3: We have already mentioned the references of the equations in the paragraphs preceding each equation.

Point 4: In general all figures need revision and clarification.

a- Fig.3,. SEM /EDS Morphological images need revision of the magnification bar not clear, also, all images must have the same magnification for the purpose of comparison under different conditions. In addition to the pictures of EDS, they are very poor and have unclear elements.

b-Fig4 : XRD patterns of the CuSbSe2 thin films must be fixed the orientations(indexed planes ) on each peak and more discussed it.

Response 4: all figures have been redone for better accuracy. Peak indexes have also been added and discussed in the manuscript.

Point 5: The language of the article has to be slightly revised.

Response 5: Thank you for your suggestion. The manuscript has been carefully revised and improved by the authors.

We sincerely hope the present manuscript with the above revisions and replies can be acceptable for publication in your journal.

Sincerely yours,  

Khadija Abouabassi

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Authors have significantly revised the manuscript and it seems to be suitable for publication. All comments are addressed with reasonable response.

Reviewer 3 Report

Thanks to the authors  , all the required modifications have been made.

regards