Eco-friendly perovskite/CZTSSe tandem cell exceeding 28% efficiency through current matching and bandgap optimization: a numerical investigationA. Maoucha, F. Djeffal, H. Ferhati and F. AbdelMalekEur. Phys. J. Plus, 138 7 (2023) 620DOI: https://doi.org/10.1140/epjp/s13360-023-04268-8