A review: Research progress in doped organic long-persistent luminescence materials based on small fused ring/heterocycle molecules

Organic long-persistent luminescence (LPL) materials have received widespread attention due to their unique advantages. An increasing number of researchers are using host-guest doping strategies to develop pure organic LPL systems. Small fused ring/heterocycle molecules are frequently being selected as guest molecules due to their long triplet lifetime and heteroatoms, which can enhance the spin-orbit coupling (SOC) and promote the intersystem crossing (ISC). Furthermore, these molecules can form various intermolecular interactions with the host matrix, thereby effectively stabilizing and protecting the generated triplet excitons, reducing nonradiative transitions, and ultimately leading to persistent room-temperature phosphorescence (RTP) phenomena. This review aims to explore the structure of guest molecules and delves into two fundamental aspects: fused ring guest molecules and fused heterocyclic guest molecules, and illustrate the influence of some typical guest molecules of fused ring/heterocycle on the doping system. In addition, the application progress of these doped materials in related fields is also discussed.