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arxiv: 2605.22453 · v1 · pith:ITQYQXGCnew · submitted 2026-05-21 · ❄️ cond-mat.mtrl-sci

Harnessing Linear and Nonlinear Optical Responses in Ferroelectric LaMoN₃ for Enhanced Photovoltaic Efficiency

Surajit Adhikari , Sanika S. Padelkar , Jacek J. Jasieniak , Alexandr N. Simonov , Aftab Alam This is my paper

Pith reviewed 2026-05-22 04:27 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci
keywords LaMoN3nitride perovskiteferroelectricshift currentphotovoltaic efficiencypressure tuningexciton bindingoptical response
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The pith

Pressure applied to LaMoN3 narrows its bandgap and boosts photovoltaic metrics by enhancing shift currents up to a peak near 15 GPa.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper examines the effects of hydrostatic pressure on the electronic, excitonic, and optical properties of the ferroelectric nitride perovskite LaMoN3. Calculations show the material stays dynamically stable to 40 GPa while its indirect gap shrinks from 2.17 eV to 1.45 eV, improving light absorption. The spectroscopic limited maximum efficiency rises and exciton binding falls with pressure, both helpful for solar cells. Bulk photovoltaic performance follows the nonlinear shift-current density and reaches a maximum around 15 GPa before dropping at higher pressures. A reader would care because the results identify concrete pressure windows where this new material could convert sunlight more effectively through combined linear and nonlinear mechanisms.

Core claim

LaMoN3 remains dynamically stable and retains its single-phase polar structure up to 40 GPa. Its indirect bandgap decreases steadily with pressure. Many-body calculations find that pressure raises the spectroscopic limited maximum efficiency while lowering exciton binding energy. The bulk photovoltaic efficiency tracks the shift-current density J_SC, peaking near 15 GPa and then declining as the nonlinear response weakens. The work therefore proposes multi-junction devices that stack layers optimized separately for linear and nonlinear photocurrents.

What carries the argument

The nonlinear shift current density J_SC generated by the material's polar symmetry, which produces a bulk photovoltaic effect whose magnitude varies with pressure.

If this is right

  • Moderate pressure improves both absorption and exciton dissociation in LaMoN3, favoring photovoltaic use.
  • The bulk photovoltaic efficiency reaches its highest value near 15 GPa before declining at higher compression.
  • Stacking absorber layers tuned for different pressure regimes could combine linear and nonlinear photocurrents in one device.
  • The material's continued stability to 40 GPa keeps these pressure-tuned phases experimentally accessible.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same pressure-tuning logic could be tested on other predicted nitride perovskites to locate additional photovoltaic candidates.
  • Thin-film strain engineering might reproduce the 15 GPa optimum at ambient pressure for practical devices.
  • If the calculated trend is confirmed, device modeling should include separate linear and nonlinear current contributions when designing nitride-perovskite solar cells.

Load-bearing premise

First-principles methods reliably predict how pressure changes the bandgap, exciton binding, and shift-current response without large errors from functional choice or neglected effects.

What would settle it

Direct measurement of shift-current density or photovoltaic efficiency in compressed LaMoN3 samples, checking whether a clear maximum occurs near 15 GPa.

Figures

Figures reproduced from arXiv: 2605.22453 by Aftab Alam, Alexandr N. Simonov, Jacek J. Jasieniak, Sanika S. Padelkar, Surajit Adhikari.

Figure 1
Figure 1. Figure 1: (a) Crystal structure, (b) phonon dispersion at 0 GPa, and (c) chemical phase [PITH_FULL_IMAGE:figures/full_fig_p008_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Electronic structure of LaMoN3 under various pressures: (a-c) Orbital-projected density of states (PDOS) simulated using PBE functional at 0 GPa, 20 GPa, and 40 GPa pressure. The inset in each of the panel demonstrates the isosurface plots of band decomposed partial charge density at HOMO and LUMO. Here, the pink and silver spheres represent Mo and N atoms, respectively, (d-f) Orbital-projected band struct… view at source ↗
Figure 3
Figure 3. Figure 3: (a) Real and (b) imaginary part of the electronic dielectric function ( [PITH_FULL_IMAGE:figures/full_fig_p020_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Nonlinear optical properties of LaMoN3 at various pressures: (a-c) Shift current conductivity (σ SC ijk) spectra at 0 GPa, 20 GPa, and 40 GPa, respectively. Only independent set of tensor components contributing to nonlinear optical current for R3c symmetry are shown here. Pressure dependence of (d) shift current density (JSC,z) with and without refractive index (n) correction (e) shift current photovoltai… view at source ↗
read the original abstract

Nitride perovskites are an emerging class of materials predicted to exhibit diverse functional properties, yet remain underexplored due to synthesis challenges of oxygen-free nitrides. Recently, LaMoN$_3$ has been reported as an oxygen-free nitride perovskite with polar symmetry, exhibiting excellent dynamic stability and ferroelectric properties under moderate pressure. However, its phase stability, linear and non-linear optical response, excitonic and polaronic behavior, and efficiency under high pressure remain unexplored. Applying pressure enables systematic tuning of the electronic structure properties, thereby facilitating the identification of phases optimized for either linear or nonlinear optical responses. Therefore, in this work, we systematically investigate these properties of LaMoN$_3$ up to 40 GPa using first-principles methods, including density functional theory, density functional perturbation theory, many-body perturbation theory (namely G$_0$W$_0$ and BSE), and tight binding approximation model. Our study shows that LaMoN$_3$ remains dynamically stable and retains its single-phase structure up to 40 GPa. The compound exhibits an indirect bandgap that decreases from 2.17 eV (0 GPa) to 1.45 eV (40 GPa) at the G$_0$W$_0$@PBE level. Using the BSE, we find that pressure enhances the SLME while lowering the exciton binding energy, both favorable for photovoltaic applications. The bulk photovoltaic efficiency trend with pressure mimics the behavior of the shift current density J$_SC$ , peaking near 15 GPa before declining at higher pressures due to a diminished nonlinear shift current response. These results highlight pressure-tuned regimes to enhance photovoltaic performance. We thereby propose multi-junction device, combining absorber layers optimized for linear and nonlinear optical currents, together boosting solar energy conversion through complementary mechanisms.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 3 minor

Summary. The manuscript claims to systematically investigate the pressure effects on the structural stability, electronic bandgap, linear and nonlinear optical responses, excitonic properties, and photovoltaic efficiency of the nitride perovskite LaMoN3 using DFT, DFPT, G0W0@PBE, and BSE methods up to 40 GPa. Key findings include retained dynamic stability, bandgap reduction from 2.17 eV to 1.45 eV, pressure-enhanced SLME with lowered exciton binding energy, and a peak in bulk PV efficiency near 15 GPa mimicking the shift current density J_SC trend, leading to a proposal for multi-junction devices combining linear and nonlinear mechanisms.

Significance. Should the numerical trends prove reliable upon further validation, the results would contribute meaningfully to the emerging field of oxygen-free nitride perovskites for optoelectronic applications. The identification of pressure as a tuning knob for optimizing both linear absorption (via SLME) and nonlinear shift currents is novel and could guide experimental efforts in high-pressure synthesis or device design. The multi-junction concept is a forward-looking suggestion. The use of many-body perturbation theory for excitons and shift currents adds technical depth, though the absence of functional benchmarks limits the strength of the quantitative claims.

major comments (2)
  1. [Methods] The G0W0 calculations are performed on PBE wavefunctions without reported benchmarks against more accurate starting points such as hybrid functionals or with spin-orbit coupling. Given that the central claim of a 15 GPa peak in photovoltaic efficiency depends on the precise pressure evolution of the quasiparticle gap and shift-current matrix elements, this omission is load-bearing and requires addressing to substantiate the reported maximum.
  2. [Results (nonlinear optical response)] No convergence tests or sensitivity analysis are presented for the k-point sampling, plane-wave cutoff, or number of unoccupied bands in the BSE and shift-current calculations as a function of pressure. This undermines confidence in the exact location of the J_SC peak at 15 GPa and the subsequent decline at higher pressures.
minor comments (3)
  1. [Abstract] The mention of a 'tight binding approximation model' is not detailed in the abstract or main text; its specific contribution to the optical or efficiency calculations should be clarified or removed if not central.
  2. [Throughout] Several instances of unclear notation for the shift current density J_SC and SLME definitions; ensure consistent use of symbols and provide explicit formulas in the methods section.
  3. [Figures] The plots of efficiency vs pressure would be improved by including data points with estimated uncertainties or by showing results from multiple k-meshes to demonstrate convergence.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the detailed and constructive feedback on our manuscript. We address the major comments point by point below and propose revisions where appropriate to strengthen the presentation of our results.

read point-by-point responses

  1. Referee: [Methods] The G0W0 calculations are performed on PBE wavefunctions without reported benchmarks against more accurate starting points such as hybrid functionals or with spin-orbit coupling. Given that the central claim of a 15 GPa peak in photovoltaic efficiency depends on the precise pressure evolution of the quasiparticle gap and shift-current matrix elements, this omission is load-bearing and requires addressing to substantiate the reported maximum.

    Authors: We acknowledge the referee's concern regarding the choice of starting point for G0W0 calculations. Although PBE is commonly used and our focus is on pressure-induced trends rather than absolute values, we agree that additional benchmarks would bolster the claims. In the revised manuscript, we will include G0W0 calculations using HSE06 as the starting point for key pressures to confirm the bandgap reduction and the position of the photovoltaic efficiency peak. For spin-orbit coupling, preliminary checks indicate negligible effects on the relevant electronic states in LaMoN3; we will add this discussion to the methods section. These additions will help substantiate the reported maximum at 15 GPa. revision: yes

  2. Referee: [Results (nonlinear optical response)] No convergence tests or sensitivity analysis are presented for the k-point sampling, plane-wave cutoff, or number of unoccupied bands in the BSE and shift-current calculations as a function of pressure. This undermines confidence in the exact location of the J_SC peak at 15 GPa and the subsequent decline at higher pressures.

    Authors: We appreciate this comment on the need for explicit convergence details. Our calculations utilized converged parameters based on prior studies and internal tests, but we did not present pressure-dependent sensitivity analyses in the manuscript. To resolve this, we will add a new subsection or supplementary material detailing convergence tests for k-point density, plane-wave cutoff, and number of bands at multiple pressure points (e.g., 0 GPa, 15 GPa, and 40 GPa). These tests confirm that the J_SC peak position is robust and not an artifact of insufficient sampling. This revision will increase confidence in the nonlinear optical response trends. revision: yes

Circularity Check

0 steps flagged

No significant circularity in derivation chain

full rationale

The paper's central results follow from direct first-principles calculations: PBE-relaxed structures, G0W0@PBE quasiparticle gaps, BSE optical spectra, and explicit evaluation of SLME and shift-current density J_SC as functions of pressure. These quantities are outputs computed from the dielectric response and matrix elements; they are not fitted parameters defined in terms of the target photovoltaic efficiency, nor do they rely on self-citation chains or ansatzes imported from prior author work. The pressure trends (SLME increase, exciton binding decrease, J_SC peak near 15 GPa) emerge from the computed spectra without reduction to the input assumptions by construction. The derivation is therefore self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claim rests on standard approximations of density-functional and many-body perturbation theory applied to a recently reported material; no new free parameters or invented entities are introduced.

axioms (2)
  • domain assumption Standard DFT and many-body perturbation theory approximations (PBE, G0W0@PBE, BSE) accurately capture pressure-induced changes in electronic structure and optical response of LaMoN3.
    Invoked throughout the description of the computational workflow in the abstract.
  • domain assumption LaMoN3 remains dynamically stable and retains single-phase polar structure up to 40 GPa.
    Stated as a direct result of the calculations and used as the basis for all subsequent optical analysis.

pith-pipeline@v0.9.0 · 5897 in / 1589 out tokens · 102073 ms · 2026-05-22T04:27:55.107952+00:00 · methodology

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Reference graph

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