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arxiv: 2605.08312 · v1 · submitted 2026-05-08 · ❄️ cond-mat.mtrl-sci

Recognition: no theorem link

Photovoltaic Possibility of Cu2SiSe3 and Cu2SnS3 Ternary Chalcogenides- Single Junction to Tandem Architecture

Saptarshi Mandal , Surbhi Ramawat , Sumit Kukreti , Ambesh Dixit
Authors on Pith no claims yet

Pith reviewed 2026-05-12 01:09 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci
keywords photovoltaicstandem solar cellsternary chalcogenidesCu2SiSe3Cu2SnS3drift-diffusion simulationsolar cell efficiency
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The pith

Simulations of a Cu2SiSe3-Cu2SnS3 tandem solar cell reach 24.1 percent efficiency, exceeding single-junction results.

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

The paper evaluates Cu2SiSe3 and Cu2SnS3 ternary chalcogenides as light absorbers in photovoltaic devices using drift-diffusion simulations. Single-junction cells optimized for thickness, carrier concentration, defect density, and interface alignment achieve 18.13 percent efficiency for Cu2SiSe3 and 15.59 percent for Cu2SnS3. A two-terminal tandem stack places the wider-gap Cu2SiSe3 on top to harvest visible light and the narrower-gap Cu2SnS3 below to capture infrared, producing combined metrics of 1.24 V open-circuit voltage, 24.6 mA cm^{-2} short-circuit current density, 79.2 percent fill factor, and 24.1 percent efficiency. A reader would care because these simpler ternary compounds could reduce material complexity compared with quaternary absorbers while the tandem design improves overall energy conversion without requiring additional junctions.

Core claim

The central claim is that drift-diffusion modeling of a two-terminal tandem solar cell with Cu2SiSe3 (band gap 1.44 eV) as the top absorber and Cu2SnS3 (band gap 0.91 eV) as the bottom absorber yields an open-circuit voltage of 1.24 V, short-circuit current density of 24.6 mA cm^{-2}, fill factor of 79.2 percent, and power conversion efficiency of 24.1 percent. These values surpass the optimized single-junction performances of 18.13 percent for Cu2SiSe3 and 15.59 percent for Cu2SnS3, confirming the viability of this absorber pair for high-efficiency tandem photovoltaics.

What carries the argument

Drift-diffusion modeling that varies absorber thickness, intrinsic carrier concentration, defect density, and energy band alignment at buffer and junction interfaces to predict device metrics for the two ternary chalcogenide absorbers.

If this is right

  • An optimized single-junction Cu2SiSe3 device reaches 18.13 percent efficiency with 38 mA cm^{-2} short-circuit current density and 0.64 V open-circuit voltage.
  • An optimized single-junction Cu2SnS3 device reaches 15.59 percent efficiency with 48.8 mA cm^{-2} short-circuit current density and 0.42 V open-circuit voltage.
  • Choice of buffer layer further modulates device parameters and opens routes for additional gains.
  • The tandem configuration demonstrates that these absorbers can be combined for broader spectrum capture and higher overall efficiency than either single junction alone.

Where Pith is reading between the lines

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

  • If the low defect densities assumed in the model prove achievable during fabrication, these materials could support lower-cost tandem cells than current multi-junction approaches that rely on more complex compounds.
  • The complementary band gaps of 1.44 eV and 0.91 eV suggest this pair could serve as a template for other thin-film tandem designs seeking similar spectral splitting.
  • Interface recombination or non-ideal band alignments not fully captured in the simulation would need experimental quantification before scaling.

Load-bearing premise

The material parameters for band gaps, carrier concentrations, defect densities, and interface alignments used in the model accurately describe real fabricated devices and introduce no additional losses.

What would settle it

Fabricating a physical Cu2SiSe3 top cell and Cu2SnS3 bottom cell tandem device and measuring its efficiency well below 24.1 percent would falsify the simulated performance claim.

read the original abstract

Cu based ternary chalcogenides are gathering attention for sustainable energy applications due to their reduced complexity compared to quaternary alternatives. We used drift diffusion modeling to evaluate the feasibility of photovoltaics employing ternary chalcogenide absorbers based on Cu2SiSe3 and Cu2SnS3. The device metrics are evaluated by analyzing absorber layer thickness intrinsic carrier concentration defect density and energy band alignment at interfacial junctions. The optimized single junction Cu2SiSe3 based device configuration achieves a power conversion efficiency of 18.13 percent exhibiting a short circuit current density of 38 mA cm^-2 and an open circuit voltage of 0.64 V. The Cu2SnS3 based device achieves an efficiency of 15.59 percent with a short circuit current density of 48.8 mA cm^-2 and an open circuit voltage of 0.42 V. We examined the impact of the buffer layer on device parameters uncovering further avenues for performance improvement. Additionally we simulated a two terminal tandem solar cell using Cu2SiSe3 Eg 1.44 eV in the upper cell to capture photons from the visible spectrum and Cu2SnS3 Eg 0.91 eV in the lower cell to absorb from the infrared spectrum. The simulated tandem architecture, featuring a VOC of 1.24 V a JSC of 24.6 mA cm^-2 a fill factor (FF) of 79.2 percent and an efficiency of 24.1 percent markedly surpassed conventional single junction devices demonstrating the viability of Cu2SiSe3-Cu2SnS3 absorber-based tandem solar cells for next generation high-efficiency solar technologies.

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

3 major / 3 minor

Summary. The paper employs drift-diffusion simulations to investigate the photovoltaic potential of Cu2SiSe3 (Eg=1.44 eV) and Cu2SnS3 (Eg=0.91 eV) ternary chalcogenides. It reports optimized single-junction efficiencies of 18.13% for Cu2SiSe3 and 15.59% for Cu2SnS3, and a tandem efficiency of 24.1% with Voc = 1.24 V, Jsc = 24.6 mA cm^{-2}, and FF = 79.2%. The work analyzes the effects of absorber thickness, carrier concentration, defect density, and interface band alignments, concluding that the tandem architecture demonstrates viability for high-efficiency solar cells.

Significance. If the assumed material parameters prove realizable in experiment, this study would indicate that these simpler ternary chalcogenides can achieve competitive tandem efficiencies, potentially offering advantages in synthesis complexity over quaternary materials like CZTS. The demonstration of tandem surpassing single-junction performance provides a theoretical basis for further exploration. However, the purely computational nature without experimental validation or parameter sensitivity analysis limits the strength of the viability claim.

major comments (3)
  1. [Abstract] The tandem performance metrics (VOC of 1.24 V, JSC of 24.6 mA cm^{-2}, FF of 79.2%, efficiency of 24.1%) are obtained by optimizing multiple free parameters including absorber layer thickness, intrinsic carrier concentration, defect density, and energy band alignment. This optimization approach, without accompanying sensitivity analysis or experimental anchoring, makes the central claim of viability dependent on the specific choice of these parameters rather than on independently verified material properties.
  2. [Device Simulation and Results] The manuscript does not provide a comparison of the input parameters (such as defect densities and carrier concentrations) with experimental values reported in the literature for Cu2SiSe3 and Cu2SnS3 or related compounds. Without this, it is unclear whether the low defect densities required for the reported efficiencies are attainable in real devices.
  3. [Tandem Architecture] The assumption that the interface band alignments and buffer layer impacts can be engineered to the optimized values without additional recombination losses or fabrication challenges is not supported by any discussion of realistic interface states or processing constraints for these materials.
minor comments (3)
  1. [Abstract] Grammatical and formatting issues: missing spaces or commas around 'percent' (e.g., '18.13 percent exhibiting'), inconsistent capitalization, and run-on sentences in the description of the tandem results.
  2. [Abstract] The abstract mentions examining the impact of the buffer layer but the summary does not include specific quantitative findings from that analysis.
  3. [References] Ensure all cited works on ternary chalcogenides include recent experimental reports on defect densities and band gaps to support the model inputs.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We are grateful to the referee for the detailed and insightful comments, which have helped us improve the clarity and robustness of our manuscript. We address each major comment below and indicate the revisions we will make.

read point-by-point responses

  1. Referee: [Abstract] The tandem performance metrics (VOC of 1.24 V, JSC of 24.6 mA cm^{-2}, FF of 79.2%, efficiency of 24.1%) are obtained by optimizing multiple free parameters including absorber layer thickness, intrinsic carrier concentration, defect density, and energy band alignment. This optimization approach, without accompanying sensitivity analysis or experimental anchoring, makes the central claim of viability dependent on the specific choice of these parameters rather than on independently verified material properties.

    Authors: We agree that the reported tandem efficiency relies on optimized parameters in our drift-diffusion simulations. To strengthen the manuscript, we will perform and include a sensitivity analysis for the key parameters (thickness, carrier concentration, defect density, and band alignment) to demonstrate the robustness of the 24.1% efficiency claim. For experimental anchoring, we will add a dedicated subsection comparing our assumed values to literature data on Cu2SiSe3 and Cu2SnS3, noting where experimental values are scarce and highlighting the need for future experimental work. This addresses the dependence on specific parameters by showing the range of viable conditions. revision: partial

  2. Referee: [Device Simulation and Results] The manuscript does not provide a comparison of the input parameters (such as defect densities and carrier concentrations) with experimental values reported in the literature for Cu2SiSe3 and Cu2SnS3 or related compounds. Without this, it is unclear whether the low defect densities required for the reported efficiencies are attainable in real devices.

    Authors: We acknowledge this omission. In the revised manuscript, we will include a new table or paragraph in the Device Simulation section that compares our input parameters—such as defect densities, carrier concentrations, and mobilities—with experimental reports from the literature for Cu2SiSe3, Cu2SnS3, and related ternary chalcogenides like Cu2ZnSnS4. This will provide context on the attainability and identify areas where further material optimization is needed. revision: yes

  3. Referee: [Tandem Architecture] The assumption that the interface band alignments and buffer layer impacts can be engineered to the optimized values without additional recombination losses or fabrication challenges is not supported by any discussion of realistic interface states or processing constraints for these materials.

    Authors: We recognize the need for a more balanced discussion of practical challenges. We will revise the Tandem Architecture section to include a discussion of potential interface issues, such as the formation of interface states, band offsets in real devices, and processing constraints like the compatibility of deposition techniques for the buffer layers and absorbers. We will cite relevant literature on interface engineering in similar chalcogenide systems to support the feasibility while acknowledging that experimental realization may introduce additional losses not captured in the ideal simulation. revision: yes

Circularity Check

0 steps flagged

No circularity: simulation outputs are direct model results under stated assumptions

full rationale

The paper performs drift-diffusion numerical simulations (standard for PV device modeling) and reports computed metrics after parameter optimization. The efficiencies, voltages, and currents are explicit outputs of the chosen inputs (thickness, carrier concentration, defect density, band alignment) rather than any claimed first-principles derivation that reduces to itself. No self-citations, self-definitional steps, or fitted-input-called-prediction patterns appear; the work is a conditional feasibility study whose limitations are acknowledged by the modeling approach itself.

Axiom & Free-Parameter Ledger

4 free parameters · 2 axioms · 0 invented entities

The central claims rest on a standard semiconductor transport model whose outputs are tuned via several adjustable inputs whose values are not independently measured in the work.

free parameters (4)
  • absorber layer thickness
    Varied to optimize device metrics for both single-junction and tandem configurations
  • intrinsic carrier concentration
    Analyzed as a variable affecting open-circuit voltage and efficiency
  • defect density
    Tuned to evaluate impact on performance and identify optimal values
  • interface band alignment parameters
    Adjusted at buffer-absorber junctions to improve simulated fill factor and current
axioms (2)
  • standard math Drift-diffusion equations accurately describe steady-state carrier transport and recombination in these thin-film devices
    Core of the modeling approach used to generate all reported J-V curves and efficiencies
  • domain assumption Literature-reported band gaps (1.44 eV for Cu2SiSe3, 0.91 eV for Cu2SnS3) and other baseline properties hold for the simulated layers
    Directly invoked to set the optical and electronic starting points for the tandem and single-junction runs

pith-pipeline@v0.9.0 · 5633 in / 1463 out tokens · 55352 ms · 2026-05-12T01:09:51.825267+00:00 · methodology

discussion (0)

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Reference graph

Works this paper leans on

3 extracted references · 3 canonical work pages

  1. [1]

    Band Anisotropy and Quartic Anharmonicity Cooperate to Drive p - Type Thermoelectricity in the Ternary Diamondlike Semiconductor Cu2SiSe3

    (1) Kukreti, S.; Ramawat, S.; Dixit, A. Band Anisotropy and Quartic Anharmonicity Cooperate to Drive p - Type Thermoelectricity in the Ternary Diamondlike Semiconductor Cu2SiSe3. Phys Rev B 2024,

    work page 2024

  2. [2]

    (2) Mathur, A

    https://doi.org/10.1103/PhysRevB.110.245202. (2) Mathur, A. S.; Upadhyay, S.; Singh, P . P .; Sharma, B.; Arora, P .; Rajput, V. K.; Kumar, P .; Singh, D.; Singh, B. P . Role of Defect Density in Absorber Layer of Ternary Chalcogenide Cu2SnS3 Solar Cell. Opt Mater (Amst) 2021, 119, 111314. https://doi.org/10.1016/j.optmat.2021.111314. (3) Kukreti, S.; Gup...

    work page doi:10.1103/physrevb.110.245202 2021

  3. [3]

    https://doi.org/10.1016/j.solener.2021.07.071

    work page doi:10.1016/j.solener.2021.07.071 2021