Regioselective Bay-Functionalization of Perylenes Toward Tailor-Made Synthesis of Acceptor Materials for Organic Photovoltaics.

The development of an efficient synthetic protocol for multiply bay-functionalized perylenes and application of these products to photovoltaics are reported. Tetrabenzyl 1-(4-tert-butylphenoxy)perylene-3,4,9,10-tetracarboxylate underwent a regioselective bromination at the 7-position followed by a further bromination at the 12-position to provide a 7,12-dibromide in high 84% yield. This compound was transformed into a tetrasubstituted C2h -symmetric dibromide by a controlled monoetherification and a final bromination. The synthetic versatility of the new brominated precursors was demonstrated by their application to cross-coupling reactions, cyanation, and derivatization to the corresponding perylene diimide (PDI). Owing to the high solubility and the raised LUMO level, the obtained tetrasubstituted PDI showed significant advantages as an acceptor material for photovoltaic applications, exhibiting a remarkably high open-circuit voltage (VOC ) reaching 1.00 V. The observed high VOC could be understood by reduction of energy offset for charge separation and non-radiative recombination loss.