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Communications Materials (2026)
We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.
Among emerging thin-film solar cells, kesterite Cu2ZnSn(S,Se)4 (CZTSSe) absorbers offer several advantages: they are based on earth-abundant, non-toxic elements and combine high stability, tunable bandgap (Eg), and flexibility, key features for integrated photovoltaic (PV) applications. Selenium-rich CZTSSe (Eg of 1.1 eV) is an ideal bottom-cell candidate for flexible tandem devices with perovskites, thereby maximising efficiency. However, CZTSSe/perovskite tandems are still underexplored. Here, we report an effective solution–based route for producing high-efficiency CZTSSe bottom cells on both rigid Mo-coated soda-lime-glass and flexible Mo-foil substrates. To optimise absorber morphology and grain size, Na-doping and Ag-alloying were performed. Then, 4-Terminal (4T) tandem devices combining kesterite- and perovskite-based subcells were designed. Solution-processed Cs0.17FA0.83Pb(I0.90Br0.10)3 perovskites (Eg of 1.63 eV) ensured optimal bandgap matching and broadened light harvesting, yielding efficiencies exceeding 22% and 20% for rigid and flexible 4T tandem devices, respectively. This proof-of-concept solution-processed tandem approach represents a promising step toward developing cost-effective and sustainable PV technologies, with promising results for future solar energy applications.
The article is based on work from COST Action Research and International Networking project ‘Emerging Inorganic Chalcogenides for PVs (RENEW-PV)’, CA21148, supported by COST (European Cooperation in Science and Technology). E.S. is grateful to the ICREA Academia program.
The authors thank Eni S.p.A. for funding C.G.’s PhD scholarship. The authors thank the research project ‘nuovi Concetti, mAteriali e tecnologie per l’iNtegrazione del fotoVoltAico negli edifici in uno scenario di generazione diffuSa’ [CANVAS], funded by the Italian Ministry of the Environment and the Energy Security, through the Research Fund for the Italian Electrical System (type-A call, published on G.U.R.I. n. 192 on 18-08-2022). This work was also supported by the ‘MUSA—Multilayered Urban Sustainability Action’ project, funded by the European Union, via NextGenerationEU, under the National Recovery and Resilience Plan (NRRP) mission 4 component 2 investment line 1.5: strengthening of research structures and creation of R&D ‘innovation ecosystems’, set up of ‘territorial leaders in R&D’. This project received funding from the European Union’s H2020 ERC-Consolidator programme under grant agreement number no. 866018 (SENSATE), and by the Science and Innovation Ministry of Spain projects number PID2023-148976OB-C41 (CURIO-CITY) and PCI2023-145971-2 (ACT-FAST, CET-Partnership 2023 program). Y.G. thanks the European Union’s Horizon research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 10115148 (LEK-PV). The authors from UPC belong to the Micro and Nanotechnologies for Solar Energy Group (MNTSolar) Consolidated Research Group of the ‘Generalitat de Catalunya’ (2021 SGR 01286). This work is also part of the Maria de Maeztu Units of Excellence Programme CEX2023-001300-M/funded by MICIU/AEI /10.13039/501100011033. J.B. acknowledges the support of the Project ‘Network 4 Energy Sustainable Transition─NEST’, Spoke 1, Project code PE0000021, funded under the National Recovery and Resilience Plan (NRRP), mission 4, component 2, investment 1.3—call for tender No. 1561 of 11.10.2022 of Ministero dell’Università e della Ricerca (MUR); funded by the European Union─NextGenerationEU. L.A.C. acknowledge the European Union’s Framework Programme for Research and Innovation Horizon Europe (2021-2027) under the Marie Skłodowska-Curie Grant Agreement No. 101068387 ‘EFESO’.
Solar Energy Research Center (MIB-SOLAR), Department of Materials Science, University of Milano-Bicocca, Milan, Italy
Carla Gobbo, Vanira Trifiletti, Giorgio Tseberlidis, Chiara Boldrini & Simona Binetti
New Energies, Renewable Energies and Materials Science Research Center, ENI S.p.A., Novara, Italy
Carla Gobbo, Paolo Biagini & Riccardo Po
CNR-ISSMC Istituto di Scienza Tecnologia e Sostenibilità per lo Sviluppo dei Materiali Ceramici, Faenza, Italy
Giorgio Tseberlidis
Photovoltaic Group, Electronic Engineering Department, Polytechnic University of Catalonia (UPC), Barcelona, Spain
Yuancai Gong, Alex Jimenez-Arguijo & Edgardo Saucedo
Barcelona Centre for Multiscale Science & Engineering, Universitat Politècnica de Catalunya (UPC), Barcelona, Spain
Yuancai Gong, Alex Jimenez-Arguijo & Edgardo Saucedo
Area di Ricerca di Tor Vergata, Istituto di Struttura della Materia, CNR, Rome, Italy
Jessica Barichello, Paolo Mariani & Aldo Di Carlo
CHOSE – Centre for Hybrid and Organic Solar Energy, Department of Electronic Engineering, University of Rome “Tor Vergata”, Roma, Italy
Luigi Angelo Castriotta, Yassine Raoui, Fabio Matteocci & Aldo Di Carlo
IPVF, Institut Photovoltaïque d’Ile-de-France (IPVF), Palaiseau, France
Yassine Raoui
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Correspondence to Carla Gobbo or Edgardo Saucedo.
The authors declare no competing interests.
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Supporting Information for Demonstration of Overcoming 20% Efficiency in Kesterite/Perovskite Tandem Solar Cells on Rigid and Flexible Substrates
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Gobbo, C., Trifiletti, V., Tseberlidis, G. et al. Demonstration of overcoming 20% efficiency in kesterite/perovskite tandem solar cells on rigid and flexible substrates. Commun Mater (2026). https://doi.org/10.1038/s43246-026-01213-x
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DOI: https://doi.org/10.1038/s43246-026-01213-x
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Communications Materials (Commun Mater)
ISSN 2662-4443 (online)
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