Pith. sign in

REVIEW 4 major objections 5 minor 43 references

Wafer-scale Synthesis of Mithrene and its Application in 2D Heterostructure UV Photodetectors

T0 review · 4 major / 5 minor · reviewed 2026-08-06 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗ Review JSON

Pith's one-line read Water vapor plus propylamine enables wafer-scale mithrene growth and photodetectors beyond 100 A/W.

desk verdict A credible small-area synthesis advance with a wafer-scale headline that currently rests on ellipsometry alone; worth reviewing seriously, but the scale-up claim and mechanism need work. read the letter →

arxiv 2506.22535 v1 pith:2AJZKG6O submitted 2025-06-27 cond-mat.mtrl-sci physics.app-ph

Maryam Mohammadi , Stefanie L. Stoll , Analía F. Herrero , Sana Khan , Federico Fabrizi , Christian Gollwitzer , Zhenxing Wang , Surendra B. Anantharaman
show 1 more author
Max C. Lemme
This is my paper · ORCID
classification cond-mat.mtrl-sciphysics.app-ph
keywords mithrenesilverphenylselenide2Dmetal-organicchalcogenideswafer-scalesynthesisUVphotodetectorsgraphenephototransistorssolid-vaporconversionphotogating
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

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

The reading

The paper claims that adding a controlled water-vapor tarnishing step and propylamine to the solid–vapor conversion of silver into silver phenylselenide (AgSePh, called mithrene) solves the two obstacles that have kept this 2D semiconductor from applications: tiny, randomly oriented crystals and small-area growth. With both additives, the authors report crystals larger than $1\,\mu\mathrm{m}$ on 100 mm wafers, with the $(001)$ face lying parallel to the substrate, and they integrate the films on graphene field-effect transistors to make blue-light photodetectors with responsivity beyond $100\ \mathrm{A/W}$ at 450 nm. The work matters because mithrene grows at 100°C, is lead-free and air-stable, and could therefore bring UV-blue detection into silicon chip back-end processing where high-temperature epitaxy is not allowed. The authors propose that the water layer corrodes the silver and that propylamine forms silver–amine complexes that slow the reaction, giving the crystals time to grow flat and oriented.

What carries the argument

The load-bearing object is the modified thermally assisted conversion (TAC) process, where a pre-tarnishing water-vapor pulse (15 s at 50°C) deposits a thin layer of water on the silver film that acts as an electrochemical electrolyte and starts to corrode the silver. In the sealed reaction vial at 100°C, the silver film sits with diphenyl diselenide powder, DMSO vapor, and 200–800 µL of propylamine, which the authors propose coordinates $\mathrm{Ag}^+$ ions and lowers their reactivity, thereby slowing the conversion of silver into AgSePh. That slower transformation is what the authors argue gives the flat, $>1\,\mu\mathrm{m}$, $(001)$-oriented crystals observed in SEM, XRD, and GIWAXS. In the photodetector geometry, the graphene field-effect transistor acts as the transport layer: photogenerated holes move into graphene while electrons remain trapped in mithrene, and the trapped charge acts as a secondary gate that multiplies the photocurrent.

What would settle it

A decisive control would be to replace propylamine with an equal volume of a non-coordinating volatile liquid of similar vapor pressure, such as hexane; if XRD and GIWAXS still show crystals above $1\,\mu\mathrm{m}$ with $(001)$ orientation, the paper's coordinating-ligand mechanism is not needed.

Watch

Extended reading notes

Core claim

The central claim is that a thermally assisted conversion route—pre-tarnishing a sputtered silver film with a 15-second water-vapor pulse, then reacting it with diphenyl diselenide and DMSO at 100°C in the presence of 200–800 µL of propylamine—produces mithrene films with crystal sizes exceeding $1\,\mu\mathrm{m}$ and a strong (002) Bragg series in XRD and GIWAXS, indicating face-on $(001)$ orientation. The same recipe transfers to a 100 mm wafer with uniform thickness (100–140 nm) and uniform optical constants. When mithrene crystals are grown on top of graphene transistors, the devices show transfer-curve shifts under 450 nm illumination that the authors attribute to hole injection and a photogating mechanism, yielding responsivities exceeding $100\ \mathrm{A/W}$ at low illumination powers with rise and fall times below 50 and 150 ms. The authors take this as evidence that mithrene is a viable air-stable photoactive layer for UV-blue detection.

Load-bearing premise

The argument rests on the assumption that propylamine works by forming silver–amine complexes that slow the conversion reaction, rather than by simply changing the gas pressure, dilution, or transport of diphenyl diselenide in the sealed reaction vial, and the paper gives no direct spectroscopic evidence of such complexes or a control with an inert additive.

Editorial extensions

If this is right

  • The growth recipe transfers directly to 100 mm wafers, so mithrene can be made at the wafer scale with uniform thickness and optical constants, a prerequisite for foundry trials.
  • Because the conversion happens at 100°C, the process is compatible with back-end-of-line integration on silicon chips, potentially replacing higher-temperature epitaxial UV photodetectors.
  • The $(001)$-oriented films show anisotropic refractive indices and extinction coefficients, implying polarization-sensitive absorption that could be used in orientation-dependent photodetection.
  • Responsivity already exceeds $100\ \mathrm{A/W}$ and shows no saturation down to the lowest tested power, so even higher sensitivity is expected at still lower illumination intensities.
  • The amine additive acts as a strain and surface-defect regulator without changing the mithrene phase, giving a dial (200–800 µL) for tuning crystal quality and film smoothness.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • If the amine's role is kinetic rather than coordinative, the same wafer-scale result might be achieved with a cheaper non-coordinating additive; the paper's own data cannot distinguish these because no inert-liquid control is reported.
  • The photogating responsivity trend suggests the real maximum responsivity is higher than $100\ \mathrm{A/W}$; measuring at sub-watt-per-square-meter powers would test whether the devices continue to improve.
  • The same tarnishing-plus-amine recipe may extend to other metal-organic chalcogenides such as copper(I) or gold(I) phenylchalcogenides, where amine coordination chemistry is also known.
  • The measured extraordinary refractive indices (about 0.71) are unusually low; if single-crystal films can be oriented further, mithrene could serve as a polarization-selective coating or waveguide cladding.
Share X Bluesky LinkedIn Reddit HN

Signed reviews

No signed human review yet.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

4 major / 5 minor

Summary. The manuscript reports a thermally assisted conversion (TAC) method for synthesizing silver phenylselenide (mithrene, AgSePh) thin films. The key procedural innovations are an H2O vapor-pulse pre-tarnishing step before the solid–vapor reaction with diphenyl diselenide, and the addition of propylamine (PrNH2) as a purported coordinating ligand. The authors claim that this approach yields mithrene crystals exceeding 1 μm, a (001) preferred orientation, and scalability to 100 mm wafers. They further integrate the mithrene films on graphene field-effect transistors and report photoresponsivities exceeding 100 A/W at 450 nm via a photogating mechanism. The small-area synthesis is characterized by XRD, SEM, AFM, GIWAXS, photoluminescence, and spectroscopic ellipsometry; the 100 mm wafer is characterized only by automated ellipsometry mapping.

Significance. If the wafer-scale synthesis claim were fully substantiated, this would be a notable advance for two-dimensional metal-organic chalcogenides, potentially enabling low-temperature, back-end-of-line-compatible UV-blue photodetectors. The small-area characterization (XRD, SEM, GIWAXS) appears internally consistent and credibly demonstrates larger, oriented crystals for the H2O/PrNH2 route. However, the central wafer-scale claim currently rests on indirect optical characterization rather than phase- or orientation-sensitive measurements, and the proposed silver-amine complexation mechanism is not directly verified. The photodetector demonstration is promising but lacks a bare-graphene control. The significance would be strengthened substantially by additional wafer-level structural data and control experiments.

major comments (4)
  1. [Results and Discussion, wafer-scale growth (p. 8) and Figure S8] The 100 mm wafer claim is supported only by automated spectroscopic ellipsometry mapping of thickness and refractive indices at 632 nm (Figure S8). No XRD, GIWAXS, SEM, or Raman data are presented for the wafer itself. A match of the average refractive indices to a single-spot measurement from a known small-area film is not phase identification: Ag2O, mixed Ag/AgSePh, or unreacted selenium species could in principle produce similar optical constants. The phrasing 'demonstrating a uniform in-plane refractive index distribution' does not establish that the wafer is phase-pure, crystalline mithrene with the claimed (001) orientation. Please provide position-dependent XRD or Raman (or GIWAXS) maps on the 100 mm wafer to support the 'wafer-scale synthesis' headline.
  2. [Synthesis of AgSePh thin films by amine addition (around Fig. 3c and refs [29-32])] The mechanistic claim that PrNH2 forms silver-amine complexes that reduce Ag+ reactivity and slow the conversion reaction is not directly supported by any complexation or kinetic evidence. The variable-amount PrNH2 experiments (200–800 μL, Figure S5) show changes in orientation and strain, but they do not exclude alternative explanations such as altered vapor pressure, dilution of Ph2Se2/DMSO, or changed transport kinetics in the sealed vial. A control experiment with an inert liquid of similar volatility, or direct spectroscopic detection of a silver-amine intermediate, would be needed to validate the proposed mechanism. The empirical recipe may stand regardless of this mechanistic interpretation, but the conclusions should not assert the complexation mechanism as established.
  3. [Photodetectors (Fig. 6e-f)] The >100 A/W responsivity is attributed to photogating in the mithrene/graphene heterostructure, but no bare-graphene control device is presented. Graphene itself can exhibit a photoresponse, and without a control it is not possible to unambiguously assign the photocurrent to the mithrene layer. Additionally, the stated rise time (<50 ms) and fall time (<150 ms) are limited by the measurement setup's 50 ms resolution; the text should explicitly state that these are upper bounds rather than resolved response times.
  4. [Figure 4 and crystal-size claims] The claim that crystals 'exceeding 1 μm' are produced is not quantified: no size distribution, standard deviation, or number of crystals analyzed is provided, and the SEM images (Figures 4a-c) show a few representative fields of view. Similarly, the 'homogeneous in-plane orientation' conclusion from GIWAXS is qualitative; a quantitative orientation distribution (e.g., rocking curves, pole figures, or azimuthal intensity profiles) would strengthen the claim and enable reproducibility assessment.
minor comments (5)
  1. [Title and Abstract] The title and abstract refer to 'UV photodetectors,' but all device measurements are performed at 450 nm (blue). While mithrene does absorb in the UV-blue, the data shown are for blue light; please harmonize the terminology.
  2. [Methods, GIWAXS] The GIWAXS description states that '5 overlapping scattering images were acquired covering an angular range of 20°' and that acquisition times 'varied depending on the scattered angles and then normalized.' Please provide details on the normalization procedure so that the intensity comparisons in Figures 4d-f are reproducible.
  3. [Figure 2f and Figure 3c] XRD intensities are presented without error bars or replicate measurements. Given that the conclusions about crystallinity and strain rely on peak intensities and peak shifts, at least one replicate or a statement about run-to-run variability would be helpful.
  4. [Conclusions] The conclusion states that PrNH2 acts as a 'coordinating ligand' that 'reduced the reactivity of Ag+ ions.' In light of Major Comment 2, this wording should be softened to reflect that the mechanism is a hypothesis consistent with the data but not directly verified.
  5. [Note on terminology] The phrase 'wafer-scale' is used for 100 mm substrates. Please clarify whether this refers to full-wafer processing or to coupons cut from a wafer, and whether the 100 mm result was reproduced on more than one wafer.

Circularity Check

0 steps flagged · score 0.0 of 10

No circularity: central claims are empirical synthesis/fabrication results, not derived from fitted parameters or self-citation chains.

full rationale

The paper's central claims are empirical: it compares XRD, SEM, GIWAXS, PL, ellipsometry, and phototransistor measurements across different pre-tarnishing and ligand conditions. No 'prediction' is reduced to a fitted value: the spectroscopic ellipsometry B-spline/Gaussian model is a fit used to report n and k, and the resulting anisotropy is interpreted consistently with independently measured GIWAXS (Fig. 4d-f), not used as evidence for the synthesis claim. The only self-citations involving coauthors (refs [20], [24], [42]) support background statements (ultrastrong light-matter coupling, BEOL compatibility, responsivity formula) and are not load-bearing for the paper's main conclusions. The wafer-scale assertion rests on ellipsometric mapping (Fig. S8) without wafer-scale XRD/SEM/GIWAXS; that is an extrapolation or evidence gap, not a circular reduction. The proposed PrNH2 silver-amine mechanism is supported by external refs [29-32] and is not used to define the synthesis outcome. No derivation chain reduces to its own inputs, so the circularity score is 0.

Assumptions & free parameters 0 free parameters · 1 assumptions · 0 invented entities

The central synthesis claim is empirical; no fitted parameters or new entities are required. The only load-bearing assumptions are chemical mechanism hypotheses carried over from prior literature.

assumptions (1)
  • domain assumption The reaction mechanism assumes that H2O vapor creates a thin water layer that electrochemically corrodes silver, and that propylamine forms silver-amine complexes that modulate Ag+ reactivity and slow conversion.
    The paper invokes these mechanisms to explain the improved growth, citing refs [11,27,29-32], but does not directly verify them for this system.

how reviews work

0 comments
Cite this review

Pith. "Pith review of Wafer-scale Synthesis of Mithrene and its Application in 2D Heterostructure UV Photodetectors." pith.science (2026). https://pith.science/paper/2AJZKG6O

@misc{pith2026250622535,
  author       = {Pith},
  title        = {Pith review of: Wafer-scale Synthesis of Mithrene and its Application in 2D Heterostructure UV Photodetectors},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/2AJZKG6O}},
  note         = {Machine review of arXiv:2506.22535}
}
abstract

Silver phenylselenide (AgSePh), known as mithrene, is a two-dimensional (2D) organic-inorganic chalcogenide (MOC) semiconductor with a wide direct band gap, narrow blue emission and in-plane anisotropy. However, its application in next-generation optoelectronics is limited by crystal size and orientation, as well as challenges in large-area growth. Here, we introduce a controlled tarnishing step on the silver surface prior to the solid-vapor-phase chemical transformation into AgSePh thin films. Mithrene thin films were prepared through thermally assisted conversion (TAC) at 100{\deg}C, incorporating a pre-tarnishing water (H${_2}$O) vapor pulse and propylamine (PrNH${_2}$) as a coordinating ligand to modulate Ag${^+}$ ion reactivity and facilitate the conversion of Ph${_2}$Se${_2}$ into an active intermediate. The AgSePh thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and grazing incidence wide-angle X-ray scattering (GIWAXS). The pre-tarnishing process, combined with organic ligands, resulted in large crystals exceeding 1 ${\mu}$m and improved homogeneous in-plane orientation, while also enabling the selective, wafer-scale synthesis of mithrene on 100 mm wafers. Furthermore, the films were integrated on planar graphene field-effect phototransistors (GFETs) and demonstrated photoresponsivity beyond 100 A/W at 450 nm, highlighting mithrene's potential for blue light-detection applications.

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

43 extracted references · 43 canonical work pages

  1. [1]

    C. Liu, J. Guo, L. Yu, J. Li, M. Zhang, H. Li, Y. Shi, D. Dai, Light Sci Appl 2021, 10, 123

    work page 2021

  2. [2]

    Ouyang, R

    X. Ouyang, R. Su, D. W. H. Ng, G. Han, D. R. Pearson, M. C. McAlpine, Advanced Science 2022, 9, 2201275

    work page 2022

  3. [3]

    C. E. Clement, J. P. Singh, E. Birgersson, Y. Wang, Y. S. Khoo, IEEE J. Photovoltaics 2021, 11, 1285

    work page 2021

  4. [4]

    M. A. Islam, M. Hasanuzzaman, N. A. Rahim, IEEE J. Photovoltaics 2018, 8, 1259

    work page 2018

  5. [5]

    Razeghi, A

    M. Razeghi, A. Rogalski, Journal of Applied Physics 1996, 79, 7433

    work page 1996

  6. [6]

    Z. Li, T. Yan, X. Fang, Nat Rev Mater 2023, 8, 587

    work page 2023

  7. [7]

    H. Chen, K. Liu, L. Hu, A. A. Al-Ghamdi, X. Fang, Materials Today 2015, 18, 493

    work page 2015

  8. [8]

    W. Fang, Q. Li, J. Li, Y. Li, Q. Zhang, R. Chen, M. Wang, F. Yun, T. Wang, Crystals 2023, 13, 915

    work page 2023

Show all 43 references
  1. [9]

    G. Wang, S. Luo, T. Di, Z. Fu, G. Xu, Angew Chem Int Ed 2022, 61, e202203151

    2022

  2. [10]

    Paritmongkol, T

    W. Paritmongkol, T. Sakurada, W. S. Lee, R. Wan, P. Müller, W. A. Tisdale, J. Am. Chem. Soc. 2021, 143, 20256

    2021

  3. [11]

    Trang, M

    B. Trang, M. Yeung, D. C. Popple, E. A. Schriber, M. A. Brady, T. R. Kuykendall, J. N. Hohman, J. Am. Chem. Soc. 2018, 140, 13892

    2018

  4. [12]

    W. S. Lee, Y. Cho, E. R. Powers, W. Paritmongkol, T. Sakurada, H. J. Kulik, W. A. Tisdale, ACS Nano 2022, 16, 20318

    2022

  5. [13]

    Paritmongkol, W

    W. Paritmongkol, W. S. Lee, W. Shcherbakov-Wu, S. K. Ha, T. Sakurada, S. J. Oh, W. A. Tisdale, ACS Nano 2022, 16, 2054

    2022

  6. [14]

    Y. L. Huang, Y. J. Zheng, Z. Song, D. Chi, A. T. S. Wee, S. Y. Quek, Chem. Soc. Rev. 2018, 47, 3241

    2018

  7. [15]

    K. S. Novoselov, A. Mishchenko, A. Carvalho, A. H. Castro Neto, Science 2016, 353, aac9439

    2016

  8. [16]

    Q. Hao, P. Li, J. Liu, J. Huang, W. Zhang, Journal of Materiomics 2023, 9, 527

    2023

  9. [17]

    Mueller, E

    T. Mueller, E. Malic, npj 2D Mater Appl 2018, 2, 29

    2018

  10. [18]

    Zhang, H

    F. Zhang, H. Lu, J. Tong, J. J. Berry, M. C. Beard, K. Zhu, Energy Environ. Sci. 2020, 13, 1154

    2020

  11. [19]

    S. K. Ha, C. M. Mauck, W. A. Tisdale, Chem. Mater. 2019, 31, 2486

    2019

  12. [20]

    S. B. Anantharaman, J. Lynch, M. Aleksich, C. E. Stevens, C. Munley, B. Choi, S. Shenoy, T. Darlington, A. Majumdar, P. J. Schuck, J. R. Hendrickson, J. N. Hohman, D. Jariwala, Nat. Photon. 2025, 19, 322

    2025

  13. [21]

    Maserati, M

    L. Maserati, M. Prato, S. Pecorario, B. Passarella, A. Perinot, A. A. Thomas, F. Melloni, D. Natali, M. Caironi, Nanoscale 2021, 13, 233

    2021

  14. [22]

    K. Yao, M. S. Collins, K. M. Nell, E. S. Barnard, N. J. Borys, T. Kuykendall, J. N. Hohman, P. J. Schuck, ACS Nano 2021, 15, 4085

    2021

  15. [23]

    A. H. Atabaki, S. Moazeni, F. Pavanello, H. Gevorgyan, J. Notaros, L. Alloatti, M. T. Wade, C. Sun, S. A. Kruger, H. Meng, K. Al Qubaisi, I. Wang, B. Zhang, A. Khilo, C. V. Baiocco, M. A. Popović, V. M. Stojanović, R. J. Ram, Nature 2018, 556, 349

    2018

  16. [24]

    Parhizkar, M

    S. Parhizkar, M. Prechtl, A. L. Giesecke, S. Suckow, S. Wahl, S. Lukas, O. Hartwig, N. Negm, A. Quellmalz, K. Gylfason, D. Schall, M. Wuttig, G. S. Duesberg, M. C. Lemme, ACS Photonics 2022, 9, 859

    2022

  17. [25]

    Maserati, S

    L. Maserati, S. Pecorario, M. Prato, M. Caironi, J. Phys. Chem. C 2020, 124, 22845

    2020

  18. [26]

    Tudela, J

    D. Tudela, J. Chem. Educ. 2008, 85, 863

    2008

  19. [27]

    T. E. Graedel, J. Electrochem. Soc. 1992, 139, 1963

    1992

  20. [28]

    Zhang, A

    K. Zhang, A. Vincze, E. Metwalli, J. Zhang, C. Liu, W. Meng, B. Zhang, J. Tian, T. Heumueller, Z. Xie, J. Luo, A. Osvet, T. Unruh, L. Lüer, N. Li, C. J. Brabec, Adv Funct Materials 2023, 33, 2303455

    2023

  21. [29]

    Schmidbaur, A

    H. Schmidbaur, A. Schier, Angew Chem Int Ed 2015, 54, 746

    2015

  22. [30]

    Nasilowski, B

    M. Nasilowski, B. Mahler, E. Lhuillier, S. Ithurria, B. Dubertret, Chem. Rev. 2016, 116, 10934

    2016

  23. [31]

    Y. Wang, Y. Zhou, Y. Zhang, W. E. Buhro, Inorg. Chem. 2015, 54, 1165

    2015

  24. [32]

    Y.-H. Liu, F. Wang, Y. Wang, P. C. Gibbons, W. E. Buhro, J. Am. Chem. Soc. 2011, 133, 17005

    2011

  25. [33]

    E. A. Schriber, D. C. Popple, M. Yeung, M. A. Brady, S. A. Corlett, J. N. Hohman, ACS Appl. Nano Mater. 2018, 1, 3498

    2018

  26. [34]

    Schwierz, Nature Nanotech 2010, 5, 487

    F. Schwierz, Nature Nanotech 2010, 5, 487

    2010

  27. [35]

    Konstantatos, M

    G. Konstantatos, M. Badioli, L. Gaudreau, J. Osmond, M. Bernechea, F. P. G. De Arquer, F. Gatti, F. H. L. Koppens, Nature Nanotech 2012, 7, 363

    2012

  28. [36]

    F. H. L. Koppens, T. Mueller, Ph. Avouris, A. C. Ferrari, M. S. Vitiello, M. Polini, Nature Nanotech 2014, 9, 780. 16

    2014

  29. [37]

    Konstantatos, I

    G. Konstantatos, I. Howard, A. Fischer, S. Hoogland, J. Clifford, E. Klem, L. Levina, E. H. Sargent, Nature 2006, 442, 180

    2006

  30. [38]

    Lopez-Sanchez, D

    O. Lopez-Sanchez, D. Lembke, M. Kayci, A. Radenovic, A. Kis, Nature Nanotech 2013, 8, 497

    2013

  31. [39]

    H. Fang, W. Hu, Advanced Science 2017, 4, 1700323

    2017

  32. [40]

    Krumrey, G

    M. Krumrey, G. Ulm, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 2001, 467–468, 1175

    2001

  33. [41]

    Skroblin, A

    D. Skroblin, A. Schavkan, M. Pflüger, N. Pilet, B. Lüthi, M. Krumrey, Review of Scientific Instruments 2020, 91, 023102

    2020

  34. [42]

    D. S. Schneider, A. Grundmann, A. Bablich, V. Passi, S. Kataria, H. Kalisch, M. Heuken, A. Vescan, D. Neumaier, M. C. Lemme, ACS Photonics 2020, 7, 1388. 17 SUPPORTING INFORMATION Wafer-scale Synthesis of Mithrene and its Application in 2D Heterostructure UV Photodetectors Mar...

    2020

  35. [43]

    Nicolas, G

    R. Nicolas, G. Lévêque, P.-M. Adam, T. Maurer, Plasmonics 2018, 13, 1219

    2018

Pith tools

Reviewed August 6, 2026 · model on record in the stance chip above.