This submission focuses on preparation and characterization of (TEBA)2SbCl5-xBrx (x = 0, 1, 2, 3, 4, 5), where TEBA is benzyltriethylammonium chloride. This material system is shown to exhibit interesting photophysical properties, which could allow its use for X-ray imaging and detection. The topic and findings reported in this work are suitable for publication in Journal of Materials Chemistry C.

The reported results such as high photoluminescence quantum yields up to ~100%, high light yield of 15000 photons MeV-1, and a low detection limit of 50.1 nGyair s-1 are impressive. Therefore, I am happy to recommend publication of this work. However, I recommend a revision before this manuscript is accepted for publication. Specific comments are listed below:
1. The writing (language) of this manuscript needs revision. I will not list specific examples of this. Instead, I suggest the editorial team reads and make suggestions to the authors.
2. “CuI(py) scintillator with the highest PLQY achieved the best scintillation performance.” Please, provide specific numbers for this claim.
3. The authors should provide atomic coordinates and Cl/Br distribution on various sites for the compounds for which they have SXRD data. Is there any preferential distribution of halides on certain sites?
4. The authors attribute emissions to triplet STEs, does this agree with Kovalnko’s work in ACS Materials Lett (ACS Materials Lett. 2020, 2, 9, 1218–1232)? I.e., are the STE emissions same as 3P-1S emissions?

The authors have addressed my comments within their capabilities. The English/writing could be better but this is acceptable. The work can now be published.