Inside Back Cover: Fast and Tunable Phosphorescence from Organic Ionic Crystals (Angew. Chem. Int. Ed. 36/2023)

Harvesting organic phosphorescence is essential for many fields in energy and materials sciences related to light generation. In their Research Article (e202305108), Andreas Steffen, Andrey Belyaev, Pi-Tai Chou, Igor O. Koshevoy et al. show that the anion–π interactions in crystalline diphosphonium iodides induce unusually fast room temperature triplet emission, which is associated with the external heavy atom effect and anion–π charge-transfer character of the excited states. This makes ionic luminophores a new design strategy beyond transition metals and organic delayed fluorophores.