Semi-Transparent Perovskite/Organic Tandem Solar Modules for Window-Integrated BIPV

Jessica Barichello^a, Micheal Wagner^b, Eswaran Jayaraman^c, Karen Forberich^b, Fabio Matteocci^d, Morten Madsen^c, Christoph J. Brabec^b, Aldo Di Carlo^a^,^b

^aCNR-ISM, Institute of Structure of Matter, Consiglio Nazionale delle Ricerche, Rome, Italy.

^bForschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (HI ERN), Dept. of High Throughput Methods in Photovoltaics, Erlangen, Germany.

^cSDU Centre for Advanced Photovoltaics and Thin-film Energy Devices (CAPE), Mads Clausen Institute (MCI), Sønderborg 6400, Denmark 2SDU Climate Cluster (SCC), Campusvej 55, 5230 Odense, Denmark

^dCHOSE—Centre for Hybrid and Organic Solar Energy, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy

Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV26)

Uppsala, Sweden, 2026 May 18th - 20th

Organizers: Gerrit Boschloo, Ellen Moons, Feng Gao and Anders Hagfeldt

Oral, Jessica Barichello, presentation 085
Publication date: 11th March 2026

Third-generation photovoltaic technologies, such as organic and perovskite solar cells, are attracting strong interest thanks to their tunable absorption, competitive efficiencies, and low-temperature, cost-effective fabrication. These advantages make them particularly promising for building-integrated photovoltaics (BIPV), where aesthetics and transparency are as important as energy generation. In this work, we present the development of a semi-transparent tandem photovoltaic module designed for window integration, combining a perovskite top cell with an organic bottom cell. The main challenge addressed is the optimization of optical and electrical coupling between the two sub-cells to maximize power conversion efficiency while preserving high transparency in the visible region. To improve light harvesting in the near-infrared range without compromising visible transmittance, a light management approach was implemented by integrating a near-infrared distributed Bragg reflector (DBR) on the organic bottom cell. Optical simulations were used to guide the design and integration strategy, resulting in a significant increase in the tandem current density. The tandem architecture was scaled to a 5 × 5 cm² device by connecting six organic cells in series for the bottom module and three perovskite cells in series for the top module, achieving excellent voltage matching with a mismatch below 1%. The resulting semi-transparent tandem solar module delivered a maximum power conversion efficiency exceeding 12%, with an average visible transmittance of 30%. In addition, it showed a light utilization efficiency (LUE) of 3.65 and a color rendering index (CRI) of 77, confirming its suitability for window-integrated applications. Finally, the transparent tandem modules were successfully integrated into a standard window, demonstrating a functional BIPV prototype.

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