Organic Long‐Persistent Luminescence from a Thermally Activated Delayed Fluorescence Electron Donor‐Acceptor Binary System

Abstract

Organic long‐persistent luminescence (OLPL) based on long‐lived charge‐separated (CS) states shows considerable emission persistence time owing to the ability to store absorbed photon energy. Herein, a novel electron donor‐acceptor (D–A) binary system consisting of electron donor 4,4,4‐tris[3methylphenyl(phenyl)amino]triphenylamine and electron acceptor tris‐[3‐(3‐pyridyl)mesityl]borane is designed and investigated for outstanding OLPL performance. It is found that the proposed binary system exhibits effective OLPL emission that lasted for more than 100 s after 1 min of ultraviolet light irradiation at room temperature (292 K). Moreover, this electron D–A binary system also exhibits thermally activated delayed fluorescence emission prior to OLPL emission. Both emission types are found to be temperature‐sensitive, which are believed to result from the occurrence of reverse intersystem crossing and the formation of a CS state, respectively. The findings enrich the electron D–A system OLPL materials and clarify the rich excited‐state transitions during OLPL emission of electron D–A systems.