Modern History of Organic Conductors: An Overview

Round 1

Reviewer 1 Report

This review article by T. Naito summarizes the historical information, topics and novel knowledges unveiled in the research area of organic conductors. Considering the large area and large number of researchers, the purpose of the review seems to be a quite difficult task, but the author succeeded to overview the area rather compactly. At first, the author review history during the period over 70 years in section 1 as an introduction. Subsequently, the paper reports the recent progresses within 20-25 years by focusing on several subjects such as Mott physics, proton dynamics, light control feature, single component conductors, Dirac system appears in the bulk crystals, and chiral conductors. Finally, it gives a brief future scope of the research area of the organic conductors. This review has cited 958 papers which have given contribution for the development and expansion of organic conductors area. As the authors commented, the research topics introduced in the article are limited and some other topics such as the Fermiology of low dimensional systems, quantum spin liquids, charge orderings and glasses, and neutral ionic systems, fullerenes, and organic FETs etc. exist. However, it needs nearly identical volume and citation numbers are necessary to cover them and author’s decision to exclude them seems reasonable. The reviewer consider that the paper is quite informative for the researchers in the area to survey previous researchers and instructive for other people and students who wants to know about organic conductors. Therefore, as the first article of the large volume of special issue (more than 18 papers at present) of “Organic conductor”, this review article is no doubt worthy of publication. The reviewer personally enjoyed in reading the manuscript. The followings are some minor comments for the author. It is better to be revised before publication.

1. The manuscript seems to be incomplete in the final part. The information of supplementary materials, authors contributions, funding, Data availability statement, acknowledgements, conflicts of interest should be written correctly. The default sentences of the regular format are remaining in this portion.
2. The author wrote in 1.2.1, L.154-L.156 that “Thus, it is beneficial that these conductors appeared in the order of 1D, 2D, and then 3D organic conductors instead of the other way around.” This meaning is not so clear. Does this message demonstrate only for the history of physical discussion on DCNQI system only or more general for organic conductors? Also, is this flow from 1D to 3D accidental or inevitable steps for the material development for stabilize conducting materials?
3. In the section 1.3, L. 280, the author describe that “These properties lead to unique phenomena, such as fluctuation [627–647], hidden states [40,648], and field-induced cascade transitions [38,494].” However, the fluctuation and hidden state are not a phenomenon. Maybe, to show the some phenomena induced by fluctuation and hidden order parameters seems better for the readers.
4. In the section 2.1, L. 340, there is a description of “Since there are a great number of reviews and books detailing such studies, we will not go into detail here.” Please insert references for this statement. Probably refs. [1-19] are the references to be cited here also (see L.47).
5. In the section 3. “concluding remarks”, the author is adopting a subtitle “Towards a new age”. From this subtitle, readers expect future subjects and future scope and future situations of the area. However, it seems that the description related to the “new age” is very short and it is commented by only one phrase. If it is possible for the author, some extra statements (several lines seems all right) on this point. It seems better to include author’s message at the end of this large volume review.
6. The inconvenient font sizes in references should be corrected. The references Nos. 76,78,80,81,82, and 613 are written by smaller fonts in the reference list. Also please confirm the citations of L.276. If the description of [226, 239, 686, 695] is correct, there is no references corresponding to #655, and #656 in the text. The appearance turn of the citations in the text is not correct order.

Author Response

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Reviewer 2 Report

The manuscript features a review article on molecular conductors. It begins with a historical overview that is focused on a few selected families of materials and related research issues. The second part reviews more contemporary trends in research, including Mott insulators, photoconductors, single-component conductors, Dirac electron systems and chiral conductors. The article is well-organized and nicely written. Also, the Author provides almost a thousand of useful references. I recommend the manuscript for publication in Crystals after minor revision related to the reference numbering described below.

The last reference cited in Line 273 is the Ref. 654. Then in Line 276 Refs. 686 and  695 appear all of a sudden, but the Author gets back to the Ref. 657 in Line 291. The Refs. 655 and 656 seem to be missing but they are not, they appear both in Line 342

Author Response

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Reviewer 3 Report

This manuscript presents a personal view of the evolution of the molecular conductors field emphasizing developments of the two last decades. It is a considerable effort for which the author should be congratulated.  I would like to point some aspects or missing references that could provide a more balanced presentation and improve this extensive work:


1) The field of molecular conductors at the beginning of this century was extensively reviewed in a special issue of Chemical Reviews on Molecular Conductors (Chemical Reviews 2004, 104, 4887-5781). This volume should be cited at the end of the first paragraph of the introduction.


2) As stated in the introduction the citations of this manuscript were presented “,,,, to provide objective descriptions of the evolution of the various research topics in the field…..” One is thus very surprised to see that in the section on single molecule conductors (section 2.4), the first paper on the HOMO-LUMO role in molecular conductors which clearly reported the main ideas of this field is not mentioned. Such reference is: "On the Band Electronic Structure of X [M(dmit)2]2 (X = TTF, (CH3)4 N, M = Ni,Pd) Molecular Conductors and Superconductors" E. CANADELL, I. E. I. RACHIDI, S. RAVY, J. P.  POUGET , L. BROSSARD and J. P. LEGROS  J. Phys-Paris 50, 2967-2981 (1989). DOI: 10.1052/jphys:0198900500190296700.

3) References 396 and 398 are the same.


4) Some interesting recent references on chiral conductors (section 2.6) could be added: (a) Short, J., Blundell, T. B. et al Chemical Communications 2020, 56, 9497-9500, (b) Mroweh , N. Adv. Mater. 2020, 32, 2002811.


5) In my opinion one of the important developments of the last decade has been the recognition of the very important role of the anions in the physics of molecular conductors.  Of course this aspect was discussed in the case of the anion ordering in Bechgaard salts but the recognition of the strong influence of anions in the physics of the 2D materials should be at least mentioned in a review of these characteristics. If the author does not have space or time to develop this aspect, he could refer to a recent and detailed review ("Donor-Anion Interactions in Quarter-Filled Low-Dimensional Organic Conductors” J.P. Pouget, P. Alemany and E. Canadell Materials Horizons 5, 590 – 640 (2018) DOI: 10.1039/c8mh00423d.) were many examples are considered.

6) In my opinion, a weak point of the present manuscript is that the notorious progress in theoretical aspects of the molecular conductors in relationship with experiments are not even briefly summarized; some of these relationships can be found in:

a- « Bond and charge ordering in low dimensional organic conductors » J.P. POUGET Physica B 407 (2012) pp1762-1770. DOI: 10.1016/j.physb.2012.01.025
b-“Interplay between electronic and structural degrees of freedom in quarter- filled low dimension conductors” J.P. POUGET Physica B 460, 45 (2015) DOI: 10.1016/j.physb. 2014.11.037) 

Author Response

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