Phthalimide-based “D–N–A” emitters with thermally activated delayed fluorescence and isomer-dependent room-temperature phosphorescence properties

Abstract

Phthalimide-based “D–N–A” emitters o-AI-Cz, m-AI-Cz and p-AI-Cz showed TADF and RTP properties due to their small ΔE_ST in both film and crystalline states. In particular, o-AI-Cz exhibited an ultralong RTP with a lifetime of 602 ms in air and remarkable afterglow, which could allow it to be used as a security ink for application in anti-counterfeiting materials. Moreover, o-AI-Cz showed intense intramolecular interaction between the donor and the acceptor subunits, while p-AI-Cz could form regular hexagonal pores with a diameter of 13.171 Å in the solid state, which might result in their different RTP properties.