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Donor-acceptor systems, group 14 elements, organic photovoltaics, organometallics, perylene diimides Keywords: donor-acceptor systems; group 14 elements; organic photovoltaics; organometallics; perylene diimides EN donor-acceptor systems group 14 elements organic photovoltaics organometallics perylene diimides 1 1 1 10/18/23 20231013 NES 231013 B Profiting from inorganic modifications b : The organic perylene structure was functionalized with inorganic silicon and germanium atoms. Cover Feature: Silicon- and Germanium-Functionalized Perylene Diimides: Synthesis, Optoelectronic Properties, and Their Application as Non-fullerene Acceptors in Organic Solar Cells (Chem. Eur. J. 57/2023). [Extracted from the article]

Organic solar cells have been continuously studied and developed through the last decades. A major step in their development was the introduction of fused-ring non-fullerene electron acceptors. Yet, beside their high efficiency, they suffer from complex synthesis and stability issues. Perylene-based non-fullerene acceptors, in contrast, can be prepared in only a few steps and display good photochemical and thermal stability. Herein, we introduce four monomeric perylene diimide acceptors obtained in a three-step synthesis. In these molecules, the semimetals silicon and germanium were added in the bay position, on one or both sides of the molecules, resulting in asymmetric and symmetric compounds with a red-shifted absorption compared to unsubstituted perylene diimide. Introducing two germanium atoms improved the crystallinity and charge carrier mobility in the blend with the conjugated polymer PM6. In addition, charge carrier separation is significantly influenced by the high crystallinity of this blend, as shown by transient absorption spectroscopy. As a result, the solar cells reached a power conversion efficiency of 5.38 %, which is one of the highest efficiencies of monomeric perylene diimide-based solar cells recorded to date., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)