Silicon‐ and Germanium‐Functionalized Perylene Diimides: Synthesis, Optoelectronic Properties, and Their Application as Non‐fullerene Acceptors in Organic Solar Cells

Abstract

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 synthesis 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 semi‐metals 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 non‐substituted 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.

Direct synthesis of gold(iii)-annulated perylene diimides via multiple C–H aurations

“…, S, Se, N, Si, Ge, P, etc .). 2–5 The fluorescence spectra of these PDI complexes revealed well-resolved vibronic structures and small Stokes shifts (approximately 11 nm). Unlike most aromatic compounds that have a transition metal directly attached to them, the cycloaurated PDI complexes displayed high fluorescence intensity.…”

“…1a). To date, chalcogen-, 2 silicon-, 3 germanium-, 3 b nitrogen-, 4 and phosphorus-annulated PDI derivatives 5 have been synthesized via palladium-catalyzed coupling reactions starting from 1,6,7,12-tetrachloro-substituted PDIs, 6 all of which display distinct characteristics such as optical and redox properties, self-assembly behavior, and charge transporting capabilities. Transition metal-annulated PDI derivatives, however, remain scarce.…”