Variations in Power Conversion Efficiency on n-Type Dye-Sensitized Solar Cells with Synthesized TiO₂ Nanoparticle: A Thickness Effect of Active Layer

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 

In this paper, the authors found the thickness effect of the TiO2 solar cells. The finding is interesting and the discussion is convincing. I would like to recommend publication after the following questions are solved.

1. The authors are supposed to double-check the format of the reference lists. i.e., [19] the journal name should be in abbreviated form. Also, the format of the issue and volume numbers should be consistent.
2. TiO2 has two phases, the rutile phase and the anatase phase. Figure 2 also reflects these two phases. Could the author also investigate which phase contributes more to the performance like larger electron densities?
3. In Table 1, Base cell P-25 is the commercial material, it still has comparable Jsc or FF performance with the 1-layer TiO2 material, did the author consider continuously adding layers (Like 5, 6, or 7 layers) to measure the performance difference? Maybe there is a limitation or upper bound that we cannot further enlarge the Jsc when adding the layer to the material.
4. Sometimes the authors use the Jsc but sometimes use the Joc (In equation (3) and (4)). If my understanding is correct, the Joc refers to the open circuit current while Jsc refers to the short circuit current. Usually, the Jsc is the standard metrice to measure the performance of solar cells. 

Comments on the Quality of English Language

language needs to be improved.

Author Response

Thank you very much for refereeing our paper and for giving us your kind corrections and suggestions as well as valuable comments. We have been accepted your fruitful comments, suggestions, and recommendations with all our heart and made our best to revise the manuscript (marked with red color for the corrected parts) with your advice. Thus, hereby, we prepared the point-by-point answers for you as followings.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript ‘Variations of power conversion efficiency in dye-sensitized solar cells with synthesized TiO2 nanoparticle: A thickness effect of active layer’ present a thorough study of the thickness of TiO2 semiconductor and its effect on photoconversion efficiency of N719-sensitized DSCs. Authors properly characterized self-manufactured TiO2 electrodes and described the observed influence on the DSCs performance. The study is logical and the experimental part was properly designed and supports conclusions.

I have several questions to the authors:

1.     What is different in this work from previous TiO2 thickness studies? There are several papers that address the influence of TiO2 thickness on DSC performance. Moreover, authors did not mention previously published results in the introduction at all.

2.     It would be good to add that the manuscript is about n-type DSCs

3.     Why TiO2 composition of rutile 80%, anatase 20% was taken as a reference? Typically, anatase is used as a dominant phase for DSCs applications.

4.     What was the type of solar simulator? Which lamp was used?

5.     How many DSC replicates did authors do for each J-V curve as well as EIS measurements?

6.     Why less recombination was observed with thicker layer?

7.     Since authors address electron diffusion time, Bode plot would help for visualization

Comments on the Quality of English Language

Some sentences are too long.

Author Response

Thank you very much for refereeing our paper and for giving us your kind corrections and suggestions as well as valuable comments. We have been accepted your fruitful comments, suggestions, and recommendations with all our heart and made our best to revise the manuscript (marked with red color for the corrected parts) with your advice. Thus, hereby, we prepared the point-by-point answers for you as followings.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This research, titled 'Variations of Power Conversion Efficiency in Dye-Sensitized Solar Cells with Synthesized TiO₂ Nanoparticles: The Effect of Active Layer Thickness,' was written by Sang-Hun Nam, Dong-Woo Ju, and Jin-Hyo Boo.

 

Here’s a revised version of your comments:

 

1.     The authors synthesized TiO₂ nanoparticles with a similar composition ratio and crystallinity as commercially available P25 TiO₂ (power?,  line 284) powder using a hydrothermal method. What is the originality of this work compared to other TiO₂ powders? Is there a new synthesis method involved? Are there unique physical properties or a monodispersed size that distinguish this TiO₂ powder?

2.     The TiO₂ powder consists of 80% rutile and 20% anatase. Is this composition ideal for dye-sensitized solar cells (DSSCs)?

3.     The DSSCs were fabricated with different TiO₂ layer thicknesses, such as 6, 12, and 17 µm. What about the effect of even greater thicknesses on performance?

4.     What is the thickness of the P-25 layer? Did you investigate the effect of thickness on DSSC performance using P-25?

5.     As the thickness increases, the efficiency also increases due to higher electron density. However, the fill factor (FF) does not increase. What could be the reason for this?

 

6.     Impedance spectroscopy was conducted, and resistance and capacitance values were determined from the equivalent circuit. What are the specific resistance and capacitance values obtained from these impedance measurements?

Comments on the Quality of English Language

line 284 

P-25 TiO2 power --> powder

Author Response

Thank you very much for refereeing our paper and for giving us your kind corrections and suggestions as well as valuable comments. We have been accepted your fruitful comments, suggestions, and recommendations with all our heart and made our best to revise the manuscript (marked with red color for the corrected parts) with your advice. Thus, hereby, we prepared the point-by-point answers for you as followings.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

1. In Figures 4, 5, 6, and 7, the “TEST-6 1, 2, and 3 layer” of DSSCs are characterized. The “TEST-6 4 layer” is not characterized. I believe the “TEST-6 4 and 5 layer” should be characterized in Figures 4, 5, 6, and 7.

 

2. “IPCE” is one of the best analytical methods for understanding Jsc. Therefore, “IPCE” and “integrated Jsc” data are needed.

Comments on the Quality of English Language

English language fine.

Author Response

Dear Reviewer 3,

Thank you very much for refereeing our paper and for giving us your kind suggestions as well as valuable comments. We have been accepted your fruitful comments and suggestions with all our heart and made our best to revise the manuscript (marked with red color for the corrected parts) with your advice. Thus, hereby, we prepared the point-by-point answers for you as followings.

Author Response File: Author Response.pdf