Recent advances in temperature and metastable-state effects on organic long-lived emission

Organic long-lived emission has evolved from classical room-temperature phosphorescence to a diverse range of systems, including persistent luminescence, thermally activated delayed emission, and thermoluminescence. Despite rapid progress, the field remains fragmented, with different studies emphasizing spin multiplicity, emission persistence, or specific material systems. Recent advances have increasingly highlighted the central role of temperature and metastable-state energetics in determining both the nature and persistence of emission. Across different material platforms, long-lived luminescence can be understood as a process in which excitation energy is stored in metastable states and subsequently released through temperature-dependent pathways. In this review, we discuss how temperature regulates the formation, stability, and release of these states and how this perspective connects seemingly distinct mechanisms, including triplet emission, trap-mediated recombination, and thermally and chemically triggered processes. By focusing on energy storage and controlled release under thermal and coupled stimuli, this work provides a coherent picture of long-lived emission and outlines key factors governing its behavior across a wide range of organic systems.