{"id":"6da029a9-53fd-4d45-a16d-efba6ee15483","arxiv_id":"2608.13053","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":7.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":0,"one_line_summary":"Substrate rotation during glancing-angle deposition encodes crystallographic torsion in PbI2, producing chiroptical responses (gabs up to 0.6) that transfer to halide perovskites with circularly polarized luminescence glum up to 0.23.","lead":"Rotating the substrate during glancing-angle deposition twists the crystal orientation inside lead iodide nanostructures as they grow, producing strong circular dichroism. The same growth-written chirality survives conversion into several halide perovskites, which emit circularly polarized light with dissymmetry factors up to 0.23.","discovery_kind":"new_method","skeptic_critique":{"model":"deepseek-v4-flash","headline":"XRD pole figures are volume-averaged and cannot distinguish continuous growth-induced crystallographic twist from a static mosaic of azimuthally rotated domains; since SEM shows twisted ribbons, the chiral morphology remains a viable origin of the measured CD.","rationale":"The reader's weakest_assumption identifies exactly the point that matters most: the measured circular dichroism could come from the twisted ribbon morphology rather than from crystallographic torsion, because the XRD pole figures are time- and volume-averaged and cannot distinguish a progressive twist from a static azimuthal mosaic. This is a genuine load-bearing gap in the argument. I agree with the reader that the appropriate verdict remains CONDITIONAL: the paper reports a striking, reproducible chiroptical effect with good handedness control, and the front-back averaging plus the handedness inversion are real supporting evidence. However, the central claim—that growth-controlled crystallographic torsion, not chiral morphology, is the origin—is not uniquely established by the data presented. The proposed depth-resolved diffraction test would settle this directly. I do not see a basis to reject the paper outright, because the effect itself appears real; but the mechanistic attribution should be verified before the claim is accepted at face value.","tokens_in":20077,"tokens_out":3410,"duration_ms":41310,"concrete_test":"FIB-lift-out a cross-section of the VP=6.7 µm L-PbI2 sample and map crystal orientation with nanobeam electron diffraction (or synchrotron micro-XRD with a sub-micron beam) at successive depths from substrate to film top. If the in-plane crystallographic azimuth rotates monotonically by roughly 135° over the 2.5 µm thickness, following the imposed substrate rotation, continuous torsion is confirmed; if domains have random static azimuths, the pole-figure broadening is a mosaic and the central claim fails.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The manuscript's central claim is that the chiroptical response originates from growth-controlled crystallographic torsion rather than from the twisted ribbon morphology. The key evidence is in the section 'Growth-controlled crystallographic torsion' (Fig. 2): as VP decreases, the (0003) pole-figure maxima broaden into a ring-like distribution at ψPF≈75°, and the ODF φ1 distribution broadens. But these are volume-averaged measurements. A continuous torsion during growth and a static mosaic of azimuthally disordered domains with different in-plane orientations both produce exactly this kind of azimuthal broadening, and the two are not separated by any reported measurement. The SEM (Fig. 1b) shows twisted ribbons, so the chiral morphology is present independently of any crystallographic twist. The front-back averaging in Methods removes second-order LDLB artifacts, but it does not remove scattering or form CD from a chiral shape. Supplementary S5 rules out only circular Bragg reflection, which requires many full turns; it does not address broadband form birefringence or differential scattering from the twisted ribbons. The VP~0 control (8 nm pitch, θchirop~0.3°) is not a morphology control because the ribbon geometry is not preserved at that rotation speed. Without depth-resolved orientation evidence, the claim that crystallographic torsion—rather than twisted morphology—is the origin of the giant CD is underdetermined.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript reports a glancing-angle-deposition (GLAD) process for PbI2 in which the substrate is rotated azimuthally during growth, producing twisted ribbon-like nanostructures with strong chiroptical responses: ellipticities up to 19°, absorption dissymmetry factors gabs-chirop approaching 0.6, and, after vapour-phase conversion to several halide perovskites, circularly polarized luminescence with glum values up to ±0.23. The central claim is that the chiroptical response originates from growth-controlled crystallographic torsion, i.e., progressive rotation of the in-plane crystallographic orientation during growth while the c-axis tilt is preserved, rather than from molecular chirality, helical morphology, or photonic architecture. Evidence includes XRD pole figures and reconstructed ODFs, handedness reversal by reversing substrate rotation, front-back averaging to remove linear-dichroism/linear-birefringence (LDLB) contributions, and comparison with non-rotating (VP=∞) and rapidly rotating (VP~0) control samples.","tokens_in":20322,"tokens_out":4455,"duration_ms":52290,"significance":"If the proposed mechanism is correct, this would be a genuinely new route to chiral halide perovskites, avoiding chiral molecular building blocks and external chiral photonic structures, and it would open a growth-based design axis for spin-optoelectronic and circularly polarized light applications. The paper has notable strengths: the handedness inversion is an independent and convincing check; the gabs estimate is explicitly conservative (Supplementary Fig. S11); the front-back averaging protocol addresses the well-known LDLB artifact; and the Supplementary Information provides unusually detailed motor, software, and hardware information for replication. However, the central attribution of the chiroptical response to crystallographic torsion is not uniquely established by the reported data, and the alternative explanation based on the twisted ribbon morphology is not fully excluded.","major_comments":[{"comment":"The pole-figure and ODF measurements are volume-averaged and cannot distinguish a continuous twist of crystallographic orientation during growth from a static mosaic of azimuthally misoriented domains. The broadening of the (0003) maxima into a ring at ψPF≈75° and the broadening of the φ1 distribution are equally consistent with either interpretation. The text states that this 'provides direct evidence of growth-controlled crystallographic torsion,' but the data shown do not support a unique conclusion. Please add depth-resolved or otherwise orientation-selective evidence, e.g., cross-sectional TEM/4D-STEM nanodiffraction, synchrotron micro-beam scanning through the film thickness, or quantitative fitting of the ODF with a torsion model, to demonstrate that the in-plane orientation rotates progressively with growth time.","section":"Growth-controlled crystallographic torsion (Fig. 2b-g)"},{"comment":"Figure 1b shows twisted ribbon-like nanostructures, so a chiral shape is present independently of any crystallographic twist. The front-back averaging described in Methods removes the second-order LDLB term, but it does not remove differential scattering or form chirality arising from the chiral morphology. Supplementary S5 explicitly rules out only the circular Bragg phenomenon, which requires multiple full turns and a well-defined helicoidal axis; it does not address broadband form birefringence, Mie-type scattering, or other shape-related chiroptical mechanisms. Therefore the load-bearing premise that crystallographic torsion, rather than the twisted ribbon morphology, is the origin of the measured CD is underdetermined. Please provide a control that preserves the ribbon morphology while removing the crystallographic torsion, or quantitative electromagnetic modelling of the measured ribbon geometry with and without crystallographic anisotropy.","section":"Growth-encoded chirality in PbI2 nanostructures as perovskite precursors; Supplementary S5"},{"comment":"The VP~0 rapid-rotation control is not a morphology-matched control. The main text itself notes that high-speed rotation modifies the structural organization, and Supplementary Fig. S3 shows markedly different absorbance profiles with additional features near 550 and 650 nm for VP~0. Consequently, the weak chiroptical response of VP~0 (θchirop~0.3°) cannot be used to isolate the role of crystallographic torsion, because both the crystallography and the ribbon geometry differ from the samples with intermediate VP. Please report SEM images of the VP~0 film and, if possible, design a control in which the morphology is unchanged while the in-plane crystallographic rotation is suppressed, or otherwise model the expected chiroptical signal from the morphology alone.","section":"Growth-encoded chirality in PbI2 nanostructures as perovskite precursors (VP~0 control, Fig. 1e and Supplementary Fig."}],"minor_comments":[{"comment":"The notation 'VP~0' is used both for 'maximum rotation speed' and for 'VP=8 nm'; please define this once in the Methods and use it consistently in the main text and figures.","section":"Methods; throughout"},{"comment":"The comparison between averaged and measured unpolarized absorbance is useful, but the discrepancy at long wavelengths raises the question of whether the same averaging choice affects the CPL glum calibration. Please state explicitly whether an analogous systematic check was performed for the photoluminescence measurements.","section":"Methods; Supplementary Fig. S11"},{"comment":"The Bragg-wavelength estimate assumes a pitch of 6.7 μm, but the accumulated twist over the 2.5 μm film thickness is only about 135°. Please state this assumption explicitly in the text so that the reader can follow the reasoning without referring to the Methods.","section":"Supplementary S5"},{"comment":"The figure caption reports error bars for glum but does not define the number of independent samples or the number of measurement repetitions per sample. Please clarify this in the caption or in the Methods.","section":"Figure 3l"}],"recommendation":"major_revision","confidential_remarks":"The paper is interesting and within the scope of the journal. The central mechanism is plausible but not yet established; the required additional measurements (depth-resolved crystallography and morphology controls) are feasible and should be requested. I recommend major revision rather than rejection, since the issue is underdetermination of a load-bearing claim, not an irreparable error."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Colleague,\n\nThe paper reports something genuinely new: a GLAD process with controlled substrate rotation that produces PbI2 nanostructures with giant chiroptical activity (ellipticity ~19°, gabs ~0.6), and that this activity transfers to several halide perovskite compositions with CPL glum up to 0.23. The handedness reversal with rotation direction and the front-back averaging for LDLB are done carefully. The VP dependence shows a clear optimum, and the control samples (no rotation, very fast rotation) show negligible CD. This is a solid experimental package.\n\nThe soft spot is the interpretation. The central claim is that chirality comes from growth-controlled crystallographic torsion—the crystal lattice itself progressively rotating during growth. The evidence is the broadening of XRD pole figures and ODF azimuthal distributions with decreasing VP. But these are volume-averaged measurements. They cannot distinguish a continuous torsion from a static mosaic of domains with different in-plane orientations. The SEM shows twisted ribbon-like nanostructures, so the chiral morphology is present. The front-back averaging corrects second-order LDLB artifacts but does not remove scattering or form CD from a chiral shape. The supplementary S5 rules out circular Bragg reflection, but that is a specific photonic mechanism; it does not rule out broadband form effects from the twisted ribbons. The VP~0 control is not a morphology control because the ribbon geometry is not preserved at that rotation speed. So the manuscript does not actually establish that crystallographic torsion—rather than the twisted morphology—is the origin of the observed CD.\n\nThis is a real gap, not a nitpick. The paper's novelty claim hinges on this distinction. Without depth-resolved orientation data (e.g., cross-sectional TEM or micro-diffraction showing continuous lattice rotation), the mechanism remains underdetermined. A control that decouples morphology from crystallographic twist would be ideal, though hard to imagine.\n\nThat said, the effect itself is likely real, and the paper is worth serious referee time. The authors are honest about LDLB contributions and make conservative gabs estimates. I would send it to review, with the mechanism as the main requested revision.\n\nWho's it for: anyone working on chiral perovskites, GLAD, or circularly polarized photonics. I wouldn't cite it in my own work until the mechanism is pinned down, but I'd follow the response.\n\nRecommendation: accept for peer review, and tell the authors to address the morphology-versus-torsion question head-on.","headline":"Real effect, strong handedness controls, but the central mechanism claim—crystallographic torsion—is not actually separated from twisted ribbon morphology; the paper deserves review but the authors will need depth-resolved texture evidence.","tokens_in":20880,"tokens_out":2520,"would_cite":false,"duration_ms":26754,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"The paper claims that chirality can be written into halide perovskites during crystal growth by rotating the substrate during glancing-angle deposition, producing crystallographic torsion with absorption dissymmetry up to 0.6 and…","keywords":["chiral halide perovskites","glancing angle deposition","circular dichroism","circularly polarized luminescence","growth-encoded chirality","crystallographic torsion","lead iodide nanostructures","vertical pitch"],"falsifier":"Map the local crystal orientation inside a single 6.7-micrometre-pitch ribbon along its growth direction using nanobeam or 4D-STEM diffraction: if the orientation does not rotate continuously with height but instead jumps among discrete azimuths consistent with a static mosaic of domains, the torsion interpretation would be falsified.","tokens_in":19918,"feed_emoji":"🌀","tokens_out":11403,"duration_ms":106381,"temperature":0.7,"pith_summary":"This paper sets out to establish that chirality can emerge as a growth-programmed property of a crystal rather than being imported from chiral molecules or photonic scaffolds. The authors combine glancing-angle deposition with controlled substrate rotation to grow PbI2 nanostructures whose crystal lattice twists progressively during growth, then convert those templates into several halide perovskites and find that the twist and its optical handedness survive. If correct, this provides a new, composition-independent route to chiral semiconductors, with handedness, torsion rate, and spectral position all controlled by deposition parameters. A sympathetic reader would care because chiral perovskites are sought for circularly polarized light sources and spin-selective electronics, and this route avoids the fragility and limited dissymmetry of molecular-chirality strategies.","feed_headline":"Rotation during growth imprints chirality on halide perovskites","feed_subtitle":"Twist direction sets handedness; absorption dissymmetry reaches 0.6 and circular emission 0.23","key_machinery":"The central object is growth-controlled crystallographic torsion: during glancing-angle deposition, substrate rotation preserves the PbI2 c-axis tilt while progressively rotating its in-plane azimuth, yielding a twisted crystalline texture rather than a helical morphology. The tuneable control parameter is the vertical pitch, defined as the film thickness deposited during one complete substrate rotation; smaller pitches mean more twist per unit height. The other load-bearing tool is front-back averaging, in which circular-dichroism spectra are recorded with the film facing the beam and then flipped 180 degrees; averaging cancels the dominant linear-dichroism and linear-birefringence artifact and isolates the genuine chiroptical component.","core_discovery":"The central discovery is growth-controlled crystallographic torsion as an origin of chirality in halide perovskites. During glancing-angle deposition at a fixed zenithal angle of 85 degrees, continuous substrate rotation progressively rotates the in-plane crystallographic orientation of PbI2 while preserving the c-axis tilt near 75 degrees, creating a twisted texture. The degree of torsion is set by the vertical pitch, the thickness deposited per full 360-degree rotation: the chiroptical response grows as the pitch decreases, peaks at 6.7 micrometers, and then weakens and reverses at smaller pitches. The strongest PbI2 samples show a chiroptical ellipticity of about 19 degrees and an absorption dissymmetry factor near 0.6, with handedness selected by the rotation direction. Vapour-phase conversion transfers the twist into MAPbI3, FAPbI3, CsPbI3, MAPbI2Br, and FAPbI2Br, giving circularly polarized luminescence with dissymmetry factors up to 0.23.","pith_inferences":["If crystallographic torsion is the active mechanism, the same substrate-rotation recipe should imprint chirality in other textured vapour-deposited semiconductors; repeating the experiment with a non-perovskite layered material such as SnS2 or BiI3 would be a direct transfer test the paper does not perform.","Because handedness is set by a mechanical rotation direction rather than by molecular synthesis, the method may extend naturally to large-area or roll-to-roll deposition, although the paper does not address scalability.","Absorption dissymmetry near 0.6 suggests the films could act as compact circular polarization filters, but the paper reports dissymmetry values rather than device figures such as extinction ratio or transmission bandwidth."],"forward_implications":["Reversing the substrate rotation direction flips the handedness of the chiroptical response, yielding nearly mirror-symmetric spectra with opposite signs.","The vertical pitch provides a continuous tuning knob: the chiroptical response grows as pitch decreases, peaks at 6.7 micrometres, then shrinks and reverses sign at 1.7 micrometres.","The chirality programmed into PbI2 survives vapour-phase conversion into five halide perovskite compositions, so bandgap and composition can be varied without losing the optical activity.","The strongest response cannot be explained by circular Bragg reflection, because the 6.7-micrometre-pitch film is only 2.5 micrometres thick and would place any Bragg resonance in the mid-infrared.","The approach achieves strong chiroptical responses without chiral molecular ligands, enantiomorphic space groups, or external photonic architectures."],"supporting_citations":[{"why":"Supplies the baseline highly textured PbI2 nanowall growth and the vapour-phase conversion route that this work extends with substrate rotation.","marker":"[31]"},{"why":"Provides the texture-analysis method used to reconstruct orientation distribution functions from the measured pole figures.","marker":"[41]"},{"why":"Provides the pole-figure inversion algorithm used to compute the orientation distribution functions.","marker":"[42]"},{"why":"Establishes the front-back averaging procedure used here to separate the chiroptical signal from linear-dichroism and linear-birefringence artifacts.","marker":"[36]"},{"why":"Documents how anisotropic linear effects contaminate circular-dichroism measurements and supports the correction applied in this work.","marker":"[37]"},{"why":"Demonstrates the chiroptic-versus-LDLB distinction in chiral 2D perovskites and underpins the averaging-based extraction of the true chiroptical component.","marker":"[25]"},{"why":"Describes helical GLAD nanostructures whose chirality is geometric, serving as the contrast case for the crystallographic-torsion mechanism claimed here.","marker":"[29]"},{"why":"Reports enantiomorphic lattice helicity in a 0D tin bromide with a pitch near 7.7 nanometres and an absorption dissymmetry factor near 3.5 × 10^-2, a benchmark for the rapid-rotation limit of this growth method.","marker":"[13]"},{"why":"Reports a 2D layered perovskite with a helicoidal pitch near 4 nanometres and an absorption dissymmetry factor near 3 × 10^-4, providing the comparison baseline for symmetry-locked helical lattices.","marker":"[40]"}],"fun_headline_variants":["Crystal growth twist imprints chirality on perovskites","Substrate rotation twists perovskites into chiral materials","Growth-controlled torsion yields giant chiral response in perovskites","Rotating crystal growth hands chirality to halide perovskites","Twisted growth: new source of chirality in perovskites"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The load-bearing premise is that the chiroptical signal originates from crystallographic torsion within the crystals, rather than from the twisted ribbon-shaped morphology visible in electron microscopy or from residual linear anisotropy that front-back averaging does not fully remove.","fun_headline_variants_meta":{"raw":{"variants":["Crystal growth twist imprints chirality on perovskites","Substrate rotation twists perovskites into chiral materials","Growth-controlled torsion yields giant chiral response in perovskites","Rotating crystal growth hands chirality to halide perovskites","Twisted growth: new source of chirality in perovskites"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000372,"raw_usage":{"total_tokens":1996,"prompt_tokens":962,"completion_tokens":1034,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":578,"completion_tokens_details":{"reasoning_tokens":954}},"tokens_in":578,"tokens_out":1034,"duration_ms":8777,"temperature":1.0,"reasoning_tokens":954,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-15T17:46:12.318229+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Map the local crystal orientation inside a single 6.7-micrometre-pitch ribbon along its growth direction using nanobeam or 4D-STEM diffraction: if the orientation does not rotate continuously with height but instead jumps among discrete azimuths consistent with a static mosaic of domains, the torsion interpretation would be falsified.","supporting_citations":[],"review_version":1}