Organic Semiconductor Devices Fabricated with Recycled Tetra Pak®-Based Electrodes and para-Quinone Methides
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have come up with an interesting idea, which is to turn the recycled Tetra Pak into an anode to fabricate flexible semiconductor devices. Moreover, they also prepared a series of p-QM compounds, to which the p-QM5 film has the potential to be used as a transparent anode in electronic devices. Proper characterizations have been conducted.
1. there are some grammar problems that need to be fixed.
Line 23, “indicate the semiconductor behavior of the p-QMs compounds.” should be “indicating the semiconductor behavior of the p-QMs compounds.”
Line 37, “functional material” should be in the plural.
2. The description and the recycling of Tetra Pak have taken up more than 1/3 of the introduction; this part should be more brief and accurately related to this work.
3. Normally, LDPE can withstand temperatures of 90 °C for a short time. However, the authors treated the Tetra Pak at 90 °C for one hour, which might affect the wettability of the substrate. It may produce greenhouse gases under this condition.
4. Apart from testing the IR spectra of the deposited p-QMs thin films, the status and 1H NMR of the p-QMs left in the crucible (at least one of them) should be added, which would contain more detailed information of the p-QMs upon thermal heating.
5. In Line 195, the authors have deposited p-QMs films, but the substrates were not mentioned throughout the paragraph, which should be also clarified in the legend of Figure 4.
Author Response
Comments and Suggestions for Authors
The authors have come up with an interesting idea, which is to turn the recycled Tetra Pak into an anode to fabricate flexible semiconductor devices. Moreover, they also prepared a series of p-QM compounds, to which the p-QM5 film has the potential to be used as a transparent anode in electronic devices. Proper characterizations have been conducted.
- there are some grammar problems that need to be fixed.
Line 23, “indicate the semiconductor behavior of the p-QMs compounds.” should be “indicating the semiconductor behavior of the p-QMs compounds.”
ANSWER. The manuscript was carefully reviewed and modification was made
Line 37, “functional material” should be in the plural.
ANSWER. The manuscript was carefully reviewed and modification was made
- The description and the recycling of Tetra Pak have taken up more than 1/3 of the introduction; this part should be more brief and accurately related to this work.
ANSWER. Thanks for the observation, the Introduction was revised and reduced, considering only the topics related to this work.
- Normally, LDPE can withstand temperatures of 90 °C for a short time. However, the authors treated the Tetra Pak at 90 °C for one hour, which might affect the wettability of the substrate. It may produce greenhouse gases under this condition.
ANSWER. Thanks for the interesting observation. Although the decomposition of LDPE can indeed produce greenhouse gases, these gases are obtained at temperatures higher than those used in this work (greater than 370°C) and are related to the degradation of the polymer. The Methodology section was complemented with this information, and also with the corresponding bibliographic references.
- Apart from testing the IR spectra of the deposited p-QMs thin films, the status and 1H NMR of the p-QMs left in the crucible (at least one of them) should be added, which would contain more detailed information of the p-QMs upon thermal heating.
ANSWER. p-QMs are very stable at high temperatures; such is the case that they are synthesized at temperatures higher than 170 °C. Infrared and NMR spectra are added to compare the bands of the initial compound with those of the thin films.
- In Line 195, the authors have deposited p-QMs films, but the substrates were not mentioned throughout the paragraph, which should be also clarified in the legend of Figure 4.
ANSWER. Information on the substrates was included. Please note that the line number has changed to 224 and the Figure is number 5.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsIn this manuscript, the authors synthesized 6 small molecules, investigated their chemical properties, and optoelectronic transport with FTO and Tetra Pak as the electrodes. Some minor revisions need the authors to address before the manuscript is considered for publication.
1. Have the 6 molecules all been reported in the literature? If one of them is new, please provide their NMR data.
2. Scheme 1, for 1a, R=H, is this incorrect? The reaction condition is under reflux and toluene’s boiling point is 110deg, but the reaction was stirred at 170 °C? Is this too high?
3. What’s the ethyl acetate/n-hexane ratio range for the purification?
4. Table 1, what’s the meaning of thickness? A large thickness can be obtained when a long deposition time is applied. Why, for example, do compounds 5 and 6 have similar deposition rates but result in a big thickness difference?
5. Also, from the chemical structure, Can you explain why 3 has the lowest deposition rate and 2 has the highest in Table 1?
6. Figure 9, Does p-QM4 show a greater dark current than light condition? This is abnormal to other compounds. Same for p-QM1 in Figure 10. Can you explain?
Comments on the Quality of English LanguageScientific writing in English needs to be improved.
Author Response
Comments and Suggestions for Authors
In this manuscript, the authors synthesized 6 small molecules, investigated their chemical properties, and optoelectronic transport with FTO and Tetra Pak as the electrodes. Some minor revisions need the authors to address before the manuscript is considered for publication.
- Have the 6 molecules all been reported in the literature? If one of them is new, please provide their NMR data.
ANSWER. The 6 molecules have been previously described in the literature (references 27-29), therefore only the proton NMR spectra are provided to compare the hydrogen shifts and integrations of the compounds, to corroborate their identity.
- Scheme 1, for 1a, R=H, is this incorrect? The reaction condition is under reflux and toluene’s boiling point is 110deg, but the reaction was stirred at 170 °C? Is this too high?
ANSWER. Thanks for the comment. Scheme 1 was corrected, because R = Ph. The reaction conditions are because between the toluene and H2O resulting from the formation of the p-QMs, an azeotrope is formed which is difficult to shift at Dean-Stark reflux conditions, at a temperature of 170 °C the Le Chatelier equilibrium is shifted towards the formation of the desired product.
- What’s the ethyl acetate/n-hexane ratio range for the purification?
ANSWER. The p-QMs were purified by column chromatography, using n-hexane/ethyl acetate eluent in a polarity gradient 99:1.
- Table 1, what’s the meaning of thickness? A large thickness can be obtained when a long deposition time is applied. Why, for example, do compounds 5 and 6 have similar deposition rates but result in a big thickness difference?
ANSWER. Indeed, high thickness can be achieved by applying a long deposition time. The thicknesses were reviewed and corrected in the Results Analysis section, and the discussion on the causes of these differences was also supplemented.
- Also, from the chemical structure, Can you explain why 3 has the lowest deposition rate and 2 has the highest in Table 1?
ANSWER. The deposition rate data for the films were reviewed and corrected, and the discussion and analysis of the results on the relationship between the deposition rate, thickness and chemical structure of the deposited compounds was expanded.
- Figure 9, Does p-QM4 show a greater dark current than light condition? This is abnormal to other compounds. Same for p-QM1 in Figure 10. Can you explain?
ANSWER. The explanation was included in the manuscript: the film of the p-QM1 compound behaves as an electrical insulator and the film with the p-QM4 compound, although it does present semiconductor characteristics, as it is part of a device it does not present photosensitive behavior.
Comments on the Quality of English Language
Scientific writing in English needs to be improved.
ANSWER. The manuscript has been carefully revised and the scientific writing in English has been corrected and improved.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors
1. The paper is too long and at points quite wordy and somewhat repetitive. I think the length can be reduced significantly
2. I am uncomfortable with the Tauc analysis as it currently stands, being generally uncomfortable with such approaches in general. Should we expect these materials to be direct or indirect? One usually knows this ahead of time, which allows for a more meaningful discussion. Why are multiple values reported for some of the samples? I don’t think this is correct and the specific linear fit used to deduce the single gap should be included.
3. AFM would probably be more revealing than SEM
4. What is the nature of the ‘devices’? These are basically resistors, so what would they be used for? Sheet resistance is thus the obvious parameter on which to focus, but this analysis is missing from the paper. It also needs to be acknowledged that the reason Tetra Pak works at all as an electrode is because the graphene coating. I don't believe that bare TP is conductive, but the authours can correct me here if I am wrong
Author Response
Comments and Suggestions for Authors
- The paper is too long and at points quite wordy and somewhat repetitive. I think the length can be reduced significantly
ANSWER. The manuscript was carefully revised and its length was decreased. The above was mainly due to a considerable reduction in the Introduction and a restructuring of the manuscript that included bringing together all the SEM results.
- I am uncomfortable with the Tauc analysis as it currently stands, being generally uncomfortable with such approaches in general. Should we expect these materials to be direct or indirect? One usually knows this ahead of time, which allows for a more meaningful discussion. Why are multiple values reported for some of the samples? I don’t think this is correct and the specific linear fit used to deduce the single gap should be included.
ANSWER. The manuscript was restructured because, indeed, from the XDR study it is known that if the films are predominantly amorphous as is the case of p-QM films, the electronic transitions are of an indirect type. Therefore, the XDR results were changed at the beginning of the discussion of the results. Additionally, to obtain the optical band gap, the Tauc analysis was replaced with a direct analysis of the absorption coefficient α, obtained from the Transmittance measurements. This is in accordance with the theory proposed by Barden et al., widely used in the calculation of the optical band gap of organic semiconductor films.
Bardenn, J.; Slatt, F.J.; Hall, L.J. Photoconductivity Conference, Wiley, New York, 1956, p. 146.
- AFM would probably be more revealing than SEM
ANSWER. AFM analysis was included.
- What is the nature of the ‘devices’? These are basically resistors, so what would they be used for? Sheet resistance is thus the obvious parameter on which to focus, but this analysis is missing from the paper. It also needs to be acknowledged that the reason Tetra Pak works at all as an electrode is because the graphene coating. I don't believe that bare TP is conductive, but the authours can correct me here if I am wrong
ANSWER. Thank you for your comments. The devices were only intended to study and compare the electrical behavior of films of para-Quinone Methides compounds. This information was expanded in the document and the information regarding the presence of graphitic carbon was also included.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe paper is acceptable in the current version.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe paper has addressed my concerns.
Comments on the Quality of English LanguageThe English has improved.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe revision is extensive and I agree with the new analysis. I have no issues with publication
