Dual carrier-selective contact transition metal dichalcogenide solar cells
Creators
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1.
California Institute of Technology
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2.
University of Chicago
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3.
University of California, Los Angeles
Abstract
Transition metal dichalcogenide (TMD) solar cells are promising candidates for high-specific-power photovoltaics due to their strong light-matter interactions, such as their high absorption coefficients. The performance of many TMD solar devices is limited by recombination losses at the semiconductor and metal electrode interface. Recent studies with silicon and perovskite solar cells overcome this challenge by employing two carrier-selective contacts to improve carrier separation and collection. In this work, we design and demonstrate the first dual selective contact TMD solar cell with both electron and hole transport layers. Resembling inverted perovskite device architectures, this solar cell consists of a vertical-junction 10-nm-thick WS2 absorber layer, C60 electron-selective contact, and PTAA hole-selective contact. This photovoltaic device exhibits an AM1.5 G open-circuit voltage of 523 mV and a power conversion efficiency of 2.4%. We characterize the carrier dynamics in the dual selective contact solar cell, which include achieving balanced transport with symmetric carrier-selective contact conductance to achieve high fill factors. We demonstrate this by showing that S-shaped I–V curves can be eliminated through reducing the thickness of the low-conductance contact. From theoretical calculations, we find that the TMD carrier lifetime limits the open-circuit voltage of TMD solar cells. To move towards the voltage limit and achieve higher solar performance, we outline steps for improving the dual selective contact solar cell architecture.
Copyright and License
© The Author(s) 2026. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Acknowledgement
We gratefully acknowledge the critical support and infrastructure provided for this work by The Kavli Nanoscience Institute at Caltech. We acknowledge support from Professor George Rossman’s lab at Caltech. We acknowledge Dr. Ruzan Sokhoyan, Kristina Malinowski, Nimisha Ramprasad, Susana Torres-Londono, and Miles Johnson for discussions and technical support. This work was supported by the Caltech Space Solar Power Project (SSPP) and DOE “Photonics at Thermodynamic Limits” Energy Frontier Research Center under grant DE-SC0019140, which supported the sample fabrication, experimental measurements, data analysis, and simulations. C.M.W., R.W.T., and J.W. acknowledge support from the NSF Graduate Research Fellowship under Grant No. 1745301, 2139433, and 1144469. C.M.W. acknowledges fellowship support from the Resnick Sustainability Institute.
Data Availability
The data that supports this study is available from the corresponding author upon reasonable request.
Code Availability
The simulation codes used in this study are in the Sentaurus TCAD and Lumerical FDTD software. The code that supports this study is available from the corresponding author upon reasonable request.
Conflict of Interest
The authors declare no competing interests.
Supplemental Material
npj_SI_Revisions_v12-Updated_RTham (download PDF )
Contributions
C.M.W. and R.W.T. contributed equally. C.M.W. fabricated the solar cell devices and conducted experimental measurements, in addition to performing Sentaurus device simulations, data calculations, and figure development. R.W.T. performed equation derivations, Lumerical and Sentaurus device simulations, data calculations and interpretation, figure development, and experimental measurements. C.M.W. and R.W.T. wrote the manuscript with input from J.W., P.R.J., and H.A.A. P.R.J. assisted with selective contact fabrication and photoconductivity measurements. J.W. performed data interpretation and equation derivations. M.M. assisted with experiments on selective contact selection and fabrication. H.A.A. supervised the project. All authors contributed to the results discussion and interpretation, in addition to manuscript preparation.
Files
s41699-026-00684-3_reference.pdf
Additional details
Related works
- Describes
- https://rdcu.be/fcr6j (URL)
Funding
- California Institute of Technology
- Caltech Space Solar Power Project
- United States Department of Energy
- “Photonics at Thermodynamic Limits” Energy Frontier Research Center DE-SC0019140
- National Science Foundation
- Graduate Research Fellowship 1745301
- National Science Foundation
- Graduate Research Fellowship 2139433
- National Science Foundation
- Graduate Research Fellowship 1144469
- California Institute of Technology
- Resnick Sustainability Institute
Dates
- Accepted
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2026-02-25Accepted
Caltech Custom Metadata
- Caltech groups
- Division of Engineering and Applied Science (EAS) , Resnick Sustainability Institute , Kavli Nanoscience Institute
- Publication Status
- Published