Power Generation in Slope-Type Thin-Film Thermoelectric Generators by the Simple Contact of a Heat Source
Round 1
Reviewer 1 Report
This manuscript mentioned that slope-type thermoelectric generators fabricated by electrodeposition and transfer to the flexible substrates. The knowledge of this research is partially helpful for researchers in a field of thermoelectric materials. However, the purpose mentioned in the manuscript is too general to explain that of this research. In addition, the design concept of the generator is not clear. It is necessary to clarify the importance of this research. The manuscript needs major revision for publication.
1. What is the design concept of these generators? For example, the length and the width of slopes must affect the generated temperature, namely, the voltage and the power of the generators must be depended on the length and the width of the slopes, not only the angles. The authors should mention how to determine the shape of the generators.
2. Why the flexibility is important in the thermoelectric generators? Actually, the flexibility of these generators was not mentioned in the manuscript. The authors should mention the importance of flexibility in thermoelectric generators, and the generation properties after bending the generators.
If the flexibility is important in the generators, the generation properties such as a cyclic bending test should be mentioned in the manuscript.
3. Thickness of the thermoelectric thin films are not mentioned. In addition, the transferring process is not clear.
Author Response
Please refer to the attached file for the response.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Authors report here power generation in slope-type flexible thin-film thermoelectric generators and the effect of slope angle on the output power. This study is acceptable for publication, however, authors should discuss other studies on TEG of similar geometries. Authors also should cite some recent publications on flexible thin films: ACS Appl. Mater. Interfaces 9, 25308, (2017); ACS Appl. Energy Mater.,1, 2261 (2018).
Author Response
Please refer to the attached file for the response.
Author Response File: Author Response.docx
Reviewer 3 Report
The article about slope-type flexible TE generators is acceptable for publication but I do not think it represents a technical or scientific advancement. The authors use geometry to manipulate DeltaT. Clearly, having the TE generator orthogonal to the heat source would be best, but with thin films that is not always possible. Why having it in an angle is more plausible -- this is not explained.
Once the DeltaT is established, Voc follows the expected linear trend vs DeltaT, and Pmax is just Voc^2/constant, not an additional physical parameter.
My main concern is actually with the determination of the conductivity (sigma). The film thickness is characterized as "approximately 1 um" (line 86-87). Since one must know the thickness of the film with a good accuracy in order to calculate sigma, the value of sigma is questionable. I would assume that patterned electrodeposition does not give a uniform thickness film, and that film porosity may be a concern. Please provide accurate value of the film thickness and variations in the thickness upon measuring in different sites.
Other suggestions:
In various places in the manuscript 300K is mentioned in a way that confuses the reader.
Line 68 - 300K is not a figure of merit.
Line 79 - "electrode area" is this the plate area or the combined area or mesh and plate?
Line 81 - change to "-0.01V vs. [name of reference]" (SHE? Ag/AgCl standard electrode?)
line 88 - change "increase" to "improve"
line 97 300K is not a Seebeck coefficient value.
Figure 1 left, the arrows are confusing. The "N-type" P-type" labels on the top and in the middle do not match.
Figure 1right, the top photograph "frames with different angles" does not display the angled sides.
line 143: what does "prepared frames with different slope angles" mean? Fig. 1right can be improved to show this.
line 147 - what does "assembled" mean?
line 154 - describe the metal electrode; a film or a wire, what material?
line 159-161: I would not consider 120ohm a "relatively low value". It is 1/6th of the device resistance. This sentence is an opinion. Can be removed.
line 202-203: "This shows... increased" quadratic dependence is due to the definition of Pmax. Fig 6b essentially repeats the data shown in Fig 5b.
Author Response
Please refer to the attached file for the response.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
This manuscript mentioned that slope-type thermoelectric generators fabricated by electrodeposition and transfer to the flexible substrates. The revised manuscript is sufficient interest for publication.
Author Response
We appreciate your valuable suggestion.
Reviewer 2 Report
Authors revised the manuscript according to the reviewer's comment. This study is acceptable for publication in the present form.
Author Response
We appreciate your valuable suggestion.
Reviewer 3 Report
The authors responded to all the concerns* of the referee and improved their manuscript, with better figures and more accurate statements.
* The authors did not satisfactory address the problem with the electrical conductivity data - the data relies on precise control and knowledge of film thickness (and porosity). But the authors can only estimate the thickness. As an alternative solution, I would suggest to change the entries in 2nd column of Table 1 from "sigma (S/cm)" to "sheet resistance (ohm/square)", since the instrument used for the research provides the sheet resistance data accurately. Then change the title of the 3rd column of Table 1 from "P.F." to "estimated P.F."
Author Response
We appreciate your valuable suggestion. In Table 1, we change from “sigma” to "sheet resistance ", and then change "P.F." to "estimated P.F." In addition, related sentences in the manuscript painted in yellow were also changed.
