The Effect of Cation Incorporation on the Elastic and Vibrational Properties of Mixed Lead Chloride Perovskite Single Crystals

Round 1

Reviewer 1 Report

The research entitled ‘Effect of Cation Incorporation on the Elastic and Vibrational Properties of Mixed Lead Chloride Perovskite Single Crystals’ discussed the valuable insights into the structural, vibrational, and elastic properties of MA_xFA_1-xPbCl₃ supported by various experimental characterizations.

Once concern is the authors mentioned in the introduction part that “In contrast, FAPbCl₃ is noteworthy among the FAPbX₃ compounds for its somewhat unexplored potential, having only undergone a few density functional theory (DFT) studies thus far [28–30], with no reported experimental studies to date.”

In fact, we found that there are several experimental research works on FAPbCl₃ have already been published in this direction. Some of them are listed below. Hence, I strongly suggest to rewrite this section accordingly. Furthermore, the author can include the following References related to this topic. 

https://doi.org/10.1021/acs.jpcc.2c00968, https://doi.org/10.1039/C9TA01160A, https://doi.org/10.1002/aelm.201600329, https://doi.org/10.1039/D0TC03559A.

The authors have written and represented the research paper in an organized and standard way. Therefore, I am suggesting to accept this research work for publications.

the quality of English Can be improved for better readability.  

Author Response

We appreciate the reviewers’ critical reading and valuable opinions on our manuscript. Comments raised by the two reviewers were considered and reflected in the revised manuscript as follows.

<Response to Reviewer 1>

1. Once concern is the authors mentioned in the introduction part that “In contrast, FAPbCl₃ is noteworthy among the FAPbX₃ compounds for its somewhat unexplored potential, having only undergone a few density functional theory (DFT) studies thus far [28–30], with no reported experimental studies to date.”

• Thank you very much for your valuable comments and it is our mistake not to include all relevant and important references. We have included all the references experimental research works on FAPbCl₃ and modified the introduction part, “In contrast, FAPbCl₃ is a distinctive compound among the FAPbX₃ compounds due to its high stability, which has proven critical in the development of highly sensitive ammonia gas sensors [28], and polymer solar cells with anode interfacial layers (AIL) that have achieved power conversion efficiency (PCE) of 8.75% [29]. Moreover, the ambipolar transport properties of FAPbCl₃ also play a significant role in the fields of UV detection and optoelectronics [29,30]. Differential scanning calorimetry (DSC) and Quasi-Elastic Neutron Scattering (QENS) experiments indicate that it undergoes phase transition from cubic to tetragonal at 271 K, and from tetragonal to orthorhombic at 258 K [31,32]. Furthermore, only a few density functional theory (DFT) studies thus far [33–35], have focused on their electronic, optical, and elastic properties. However, no research studies have yet integrated mixed A site cation composition for lead chloride. Therefore, our aim is to fill this research gap by analyzing the mixed MA_xFA_1-xPbCl₃”

Reviewer 2 Report

The paper of Junaid et al. reports new data on the crystal chemical relationship between structural features and elastic and vibrational properties of mixed halide single crystals with the general formula MAxFA1-xPbCl3. 

In principle, the paper is worth publishing, however I would like to recommend the author to provide the refinement of crystal structures of studied compounds as well as the DFT data on the optimisation of the structures. I would have to mention that for hybrid perovskites the shift between the "perovskite" layers is controlled by the orientation of molecular guests [e.g. 10.1021/acs.chemmater.1c00382;  10.1021/acs.chemmater.0c03935]. I think it would be nice to show the accurate structural data to prove the structural features. 

The English is rather good.

Author Response

<Response to Reviewer 2>

1. In principle, the paper is worth publishing, however I would like to recommend the author to provide the refinement of crystal structures of studied compounds as well as the DFT data on the optimisation of the structures. I would have to mention that for hybrid perovskites the shift between the "perovskite" layers is controlled by the orientation of molecular guests [e.g. 10.1021/acs.chemmater.1c00382; 10.1021/acs.chemmater.0c03935]. I think it would be nice to show the accurate structural data to prove the structural features.

• Thank you very much for your valuable comments. Our main concern in this study was to extract the exact information of the lattice constant and the density for obtaining elastic constants, which have not been obtained before. Thus the data in Fig. 3 was enough for our research purpose. Even though we admit that structural refinement and DFT approach are of paramount importance for better understanding of this system, they are beyond the scope of this paper, and we hope to pursuit those approaches in our forthcoming research.