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Excitons under strain: light absorption and emission in strained hexagonal boron nitride

by Pierre Lechifflart, Fulvio Paleari, Claudio Attaccalite

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Submission summary

Authors (as registered SciPost users): Claudio Attaccalite
Submission information
Preprint Link:  (pdf)
Date accepted: 2022-04-04
Date submitted: 2022-03-14 11:46
Submitted by: Attaccalite, Claudio
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
  • Condensed Matter Physics - Computational
Approaches: Theoretical, Computational


Hexagonal boron nitride is an indirect band gap material with a strong luminescence in the ultraviolet. This luminescence originates from bound excitons recombination assisted by different phonon modes. The coupling between excitons and phonons is so strong that the resulting light emission is as efficient as the one of direct band gap materials. In this manuscript we investigate how uniaxial strain modifies the electronic and optical properties of this material, and in particular how it affects the exciton-phonon coupling. Using a formulation of this coupling based on finite-difference displacements, recently developed by some of us, we investigate how phonon-assisted transitions change under strain. Our results open the way to the study of phonon-assisted luminescence in strained materials from first principles. Our findings are important both for experiments that directly probe \hbn under strain or for those in which it is used as substrate for other 2D material with a lattice mismatch.

Author comments upon resubmission

Dear Editor,

we thank you for sending us the Referees' comments on the manuscript:

“Excitons under strain: light absorption and emission in strained hexagonal boron nitride”

Following the editor’s suggestion we would like to submit a new version of the present manuscript to
SciPost Physics.
The third referee recommended the publication of the manuscript in the present form in SciPost Physics,
while the first one asked "some adjustments and complementary information".
In the present new version of the manuscript we added all required information and computational
details requested by the first referee.
The second referee recommends the publication in SciPost Core because in his/her opinion
our results constitute a "lack of a breakthrough in the theory" and do not reproduce the experimental data.
We disagree with both these statements.
We think that the comparison with experiment cannot be a criterion to discredit this work,
because in the past several experimental results on PL in BN-bases systems have turned out to be incorrect.
Furthermore, in the experiments there are effects not taken into account
by the present approach such as sample curvature and surface effects that neither we
nor the experimentalists know how to evaluate for the moment.
Regarding the "lack of a breakthrough in the theory" we would like to point out
that although there are many works in the literature on the effect of strain on the electronic structure,
to our knowledge this is the first work that investigates how strain modifies the exciton-phonon coupling from first-principles.
In the new version of the manuscript we underlined this important point,
that we think makes our work worth publishing in SciPost Physics.

All changes are detailed in the answer attached to this letter.

Yours sincerely,
Pierre Lechifflart
Fulvio Paleari
Claudio Attaccalite

List of changes

1) we improved the abstract, now it explicitly mentions the new method for the luminescence calculation

2) add a reference to this new paper "Vibrational Properties in Highly Strained Hexagonal Boron Nitride Bubbles"
where for the first time, strains comparable with the one studied in our work have been realized

3) Added more computational detail on the optical absorption and
luminescence calculation

4) Corrected and improved discussion on bright and dark excitons

5) Added a new figure with the optical absorption under strain

6) Improved conclusions

Published as SciPost Phys. 12, 145 (2022)

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Anonymous on 2022-03-27  [id 2329]


The authors have replied to the three Reports on v2 and have submitted a new v3. (I am the author of Anonymous Report 3 on 2022-2-8).

The clarifications and a new Figure added to the manuscript (which address points made in Anonymous Report 1 on 2022-2-4 ) are helpful. My view that the paper should be accepted for publication in SciPost Physics is reinforced.

Anonymous Report 2 on 2022-2-7 recommended that the paper is not suitable for SciPost Physics and should be published in SciPost Physics Core instead, because of imperfect agreement with experiment. I support the paper's authors in disagreeing with this view: the distinctive *ab initio* combination of luminescence spectra, phonon dispersion and the effect of strain is already a technical *tour de force* which I am confident will be developed further in the future: in this way I believe it meets the criterion "*Open a new pathway in an existing or a new research direction, with clear potential for multipronged follow-up work*".