Overcoming efficiency and manufacturing challenges in fully-textured perovskite/silicon tandem solar cells

Oussama Er-raji^1,2, Oliver Fischer^1,2, Christoph Messmer^1,2, Mohamed Mahmoud^1,2, Vladyslav Hnapovskyi³, Sofiia Kosar³, Rakesh Pradhan³, Bhushan. P. Kore^1,2, Johanna Modes^1,2, Martin Bivour^1,2, Jonas Schön^1,2, Florian Schindler¹, Stefaan De Wolf³, Martin Hermle¹, Martin C. Schubert¹, Stephan Riepe¹, Ulrike Hatt¹, Patricia S. C. Schulze¹, Juliane Borchert^1,2, Stefan W. Glunz^1,2

¹Fraunhofer Institute for Solar Energy Systems ISE, Germany

²University of Freiburg, Department of Sustainable Systems Engineering (INATECH),Germany

³King Abdullah University for Science and Technology (KAUST), KSA

E-mail: oussama.er-raji@ise-extern.fraunhofer.de

Abstract

Two-terminal (2T) fully-textured perovskite/silicon tandem solar cells represent a promising route toward highly efficient photovoltaic technology with low levelized cost of electricity. By conformally depositing the <1 µm-thick perovskite top cell onto an industry-standard textured silicon cell with micrometer-sized pyramids (>1 μm), the existing silicon manufacturing infrastructure at TW scale and its production technologies can continue to be used, and the power capacity can theoretically be increased by up to 50% through tandem technology. In this contribution, we address the key challenges associated with the realization of fully-textured perovskite/silicon tandem solar cells, including conformal perovskite absorber deposition on complex surface morphologies via 2-step hybrid evaporation/wet-chemistry and sequential evaporation methods, and the formation of high-quality interfaces throughout the device stack. These developments are guided by advanced characterization techniques capable of identifying loss mechanisms within the individual sub-cells, together with opto-electrical simulations that accurately describe device operation and performance limitations. Finally, we demonstrate scalable deposition approaches for the various layers of the perovskite sub-cell and transition the bottom-cell design from SHJ to TOPCon. This is implemented in the Pero-Si-SCALE platform at Fraunhofer ISE, providing a pathway toward the industrial implementation of high-efficiency fully-textured perovskite/silicon tandem solar cells.

Keywords: Perovskite; Silicon; Tandem solar cells

Biography:

Dr. Oussama Er-raji is a researcher at Fraunhofer ISE and the Albert-Ludwigs-Universit
ät Freiburg, specializing in the development of perovskite/silicon tandem solar cells. He earned his Bachelor’s degree in Mechanical engineering from Université de Bordeaux and his Master’s degree in Energy and Environmental Science from École Polytechnique in France. He then completed his Ph.D. at the Albert-Ludwigs-Universität Freiburg in Germany, during which he conducted his research at Fraunhofer ISE. Dr. Er-raji played a key role in reaching the record-certified power conversion efficiency of 31.6% for fully-textured perovskite/silicon tandem solar cells in 2024. He has authored and co-authored over 30 peer-reviewed publications in leading journals such as Joule, Science, and Nature Energy, contributing to the field of high-efficiency perovskite/silicon solar cell technologies. In addition to his research, he serves as a guest lecturer at the Albert-Ludwigs-Universität Freiburg.