Study of Annealing Temperature Effect on the Photovoltaic Performance of BiOI-Based Materials
Round 1
Reviewer 1 Report
Authors have addressed my comments so that the acceptance is recommended.
Author Response
We thank you very much for this suggestion. The manuscript has been checked with the grammar check for revising the grammar, punctuation, and misspelling. Furthermore, the checking of sentence and syntax has been attempted to make the manuscript to be more clear and concise.
Reviewer 2 Report
The authors have not addressed the following previous comments:
4. For the analysis in Figure 5B, the authors should clarify how many devices were measured for each temperature
-> Unless I missed it, the authors still don't state in the manuscript how many devices were measured for each temperature. I also didn't see many/any details about how the cells were fabricated.
5. Authors state: “The less (001) plane of Bi7O9I3 in the XRD pattern (Fig. 1) compared to those annealed BiOI at 100oC might cause the better ability in light absorption.” The reduction in the (001) peak is not obvious in Figure 1. The authors could provide the integrated peak intensity ratio (001):(110) for the two temperatures to support this statement.
-> The authors continue to state that the (001) XRD peak intensity is reduced for the 300C sample, but the only intensity ratio they provide indicates that the (001) peak intensity actually increases: "We have calculated the intensity ratio of (001):(110) facet and the evaluated ratio for both annealed sample at 100 and 300 oC were nearly similar, which were 6.1 and 6.3, respectively". Are the referring to the fact that the (001) peak at 300C has a lower count number in the XRD data? If so, this suggests a fundamental misunderstanding of XRD measurements. The peak counts is arbitrary - what matters is the relative intensity of the various peaks (either peak values or integrated).
6. Grammatical corrections are required throughout to improve the quality of the manuscript.
Author Response
Dear Reviewer 2,
We thank you very much for the critical comments and valuable suggestions to our manuscript. We appreciate reviewer for spending time to read our paper and giving the valuable comments. We believe that the comments from reviewer help us to improve our revised paper that we are resubmitting for review process. Here we added some information as our feedback in the green highlighted sentence. Once again, we thank you very much for this help.
Yours sincerely,
Anissa A. Putri, S. Kato, N. Kishi and T. Soga
For the analysis in Figure 5B, the authors should clarify how many devices were measured for each temperature
-> Unless I missed it, the authors still don't state in the manuscript how many devices were measured for each temperature. I also didn't see many/any details about how the cells were fabricated.
We thank you very much for pointing this out. As we mentioned before, we prepared 2 devices for our solar cell measurement. However, in the displayed data, we only showed the best result. During the measurement on both devices, we obtained the same trend in their Jsc and Voc values but we did not make the average value since it would make the lower value of calculated Jsc and Voc. The confidence of showing the best measured data only was supported by our composite cell of annealed BiOI and TiO2. We have made the same device structure by addition of TiO2 and the same trend was revealed by the maximum performance of BiOI 300 oC. We tried to add the information in the subsection 3.4 and changed the figure with additional information of 2 devices.
Authors state: “The less (001) plane of Bi7O9I3 in the XRD pattern (Fig. 1) compared to those annealed BiOI at 100oC might cause the better ability in light absorption.” The reduction in the (001) peak is not obvious in Figure 1. The authors could provide the integrated peak intensity ratio (001):(110) for the two temperatures to support this statement.-> The authors continue to state that the (001) XRD peak intensity is reduced for the 300C sample, but the only intensity ratio they provide indicates that the (001) peak intensity actually increases: "We have calculated the intensity ratio of (001):(110) facet and the evaluated ratio for both annealed sample at 100 and 300 oC were nearly similar, which were 6.1 and 6.3, respectively". Are the referring to the fact that the (001) peak at 300C has a lower count number in the XRD data? If so, this suggests a fundamental misunderstanding of XRD measurements. The peak counts is arbitrary - what matters is the relative intensity of the various peaks (either peak values or integrated).
We thank you very much for this comment. We got a lesson and we have learned the important thing by this comment. As we noticed that the peak intensity reflect the number of crystal in the sample, we used the factual intensity to discuss and calculate the integrated intensity as we refer to the previous work from other researchers [1]. However, after reading the comment from reviewer and reading again for the XRD analysis method, we have realized that y-axis in the diffractogram cannot give the absolute scaling and it is not possible to do quantification by direct comparison of the intensity value as there are many factors can affect the peak intensity.
We have calculated the integration of peak area in the diffraction pattern of our sample. We obtained the slight difference in the ratio of I(001)/I(110) between the annealed BiOI at 100 and 300 oC, whereas the ratio of those planes at sample 300 oC was lower than at 100 oC. It means that the ratio of (001) at sample 100 oC was more than in 300 oC. The annealed sample at 100 oC and 300 oC had the integrated I(001)/I(110) ratio around 8.5 and 7.6, respectively. This result could suggest that the treatment at 300 oC reduced the (001) plane although it was a small changing and the dominant plane both in sample 100 oC and 300 oC is still (001) plane. By the reducing in (001) plane may result in the smaller crystal and material in an annealed sample at 300 oC (Bi7O9I3) and it seem to have a slightly higher of surface area. However, as it may be difficult to give evidence about the crystal contribution on our device precisely, we consider for changing this discussion and we propose a discussion based on the size of material and the broadening of FWHM peaks as the reason why sample at 300 oC had the best performance abd it is suitable for electrochemical device. This has been added to the subsection 3.4.
[1] L. Zhang, C.G. Niu, G.X. Xie, X.J. Wen, X.G. Zhang, G.M. Zeng, ACS Sustain. Chem. Eng. 5 (2017) 4619–4629.
Grammatical corrections are required throughout to improve the quality of the manuscript.
We thank you very much for this suggestion. The manuscript has been checked with the grammar checker for revising the grammar, punctuation, and misspelling. Furthermore, the checking of sentence and syntax has been attempted to make the manuscript to be more clear and concise.
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 authors doctor blade BiOI films and then anneal them at different temperatures to form different oxygen-rich/iodine-poor variants. They characterize the structural, morphological, and optical properties of these different films and test them as anodes in solar cells. As the annealing simultaneously induces variation in the composition and morphology of the films, it is difficult to relate the variation in photovoltaic performance to either the composition or morphology. Nonetheless, this work will serve as a useful reference for those developing solar cells based on BiOI. It could be published once a few points are addressed: 1.The authors speculate that the sample annealed at 300C is Bi7O9I3, due to a slight shift in the position of 3 of the XRD peaks. However this shift is very slight and I don’t believe there is any direct evidence (e.g. XPS) provided to confirm this change in composition, so the authors should be careful in referring to this sample as Bi7O9I3. 2.Authors state that “the measured layer thickness of BiOI nanosheets was to be around 37.5 nm and 25 nm for annealed BiOI at 100 and 300oC”. It is not clear how these thicknesses were determined. 3.Class of solar simulator used should be specified, e.g. AAA. 4.For the analysis in Figure 5B, the authors should clarify how many devices were measured for each temperature. 5.Authors state: “The less (001) plane of Bi7O9I3 in the XRD pattern (Fig. 1) compared to those annealed BiOI at 100oC might cause the better ability in light absorption.” The reduction in the (001) peak is not obvious in Figure 1. The authors could provide the integrated peak intensity ratio (001):(110) for the two temperatures to support this statement. 6.Grammatical corrections are required throughout to improve the quality of the manuscript.
Author Response
Please see the attached file.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript reports the effects of annealing temperature on the photovoltaic properties of BiOI-based solar cells. The key issue of article is very poor efficiency [0.069%] and novelty [Refs. 12, 13, 15]. The discussion is insufficient except for the crucial issues. There are several comments here:
1. Device structure and band structure are required.
2. FF is low. The sheet resistances of BiOI films are required.
3. IPCE is required.
4. Series and shunt resistances of cells are required.
Therefore, I can not recommend it to publish.
Author Response
Please see the attached file.
Author Response File: Author Response.docx
Reviewer 3 Report
This work discussed the effect of annealing temperature on the photovoltaic properties of BiO based solar cells. Two comments are suggested to discuss further in the revised manuscript.
1. For photovoltaic test, in addition to the change of crystal orientation, there are also some other effects, such as thickness shrinkage, increase of surface area that resulted in the better performance when comparing the anneal temperatures of 300 and 100 degree C. Did author consider to fix the thickness of BiO film and test the I-V curves of solar cells under various anneal temperatures? In addition, BET measurements are required to investigate the thickness change. 2. Authors should discuss the reason for the optimal Voc at 300 anneal temperature.
Author Response
Please see the attched file.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The power conversion efficiency in this work is almost no efficiency. The best case is only 0.069% of efficiency and photocurrent of ~70 uA, such that no ICPE data. For a DSSC-type solar cell, it is not worth to publish. >1% efficiency of BiOI-based DSSC has reported.
