Designing Charge Carrier and Exciton Dynamics for Efficient Organic Long-Persistent Luminescence

Organic long-persistent luminescence (OLPL) relies on the generation and storage of charges that later recombine to produce delayed emission. Efficient OLPL, therefore, requires simultaneous control of charge separation, long-lived charge retention, and emissive charge recombination, which makes rational material design difficult. Here, we analyze the individual steps of the OLPL mechanism to understand how each process contributes to persistent emission and how they can be combined to achieve a highly performing OLPL. We show that tuning the molecular orbitals of constituent molecules controls charge generation, charge retention, and the energy of the intermolecular charge-transfer (CT) excited states, whereas the alignment of intermolecular CT and locally excited (LE) states determines whether recombination produces weak CT or bright LE emission. Based on this understanding, we combined CT-mediated charge generation with trapassisted charge retention and achieved bright LPL through LE–CT hybridization. Here, we provide a practical route for identifying and optimizing materials suitable for efficient, air-stable, and color-tunable OLPL.