Delayed fluorescence

{
  "id": "MLC-T-CHM-002965",
  "term": "Delayed fluorescence",
  "field": "Chemistry",
  "definition": "Luminescence from the first excited singlet state with a lifetime far longer than that of prompt fluorescence, because the singlet is repopulated from a triplet state. In E-type, thermally activated delayed fluorescence, reverse intersystem crossing from the triplet occurs when the singlet-triplet gap is small, so emission strengthens as temperature rises. In P-type, two triplets annihilate to give one excited singlet, as first seen with pyrene.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "annihilation",
    "biphotonic process",
    "delayed luminescence",
    "fluorescence",
    "lifetime",
    "phosphorescence",
    "radiationless transition",
    "radical ion",
    "singlet state",
    "triplet state"
  ],
  "references": [
    "PAC, 1984, 56, 231. 'Nomenclature, symbols, units and their usage in spectrochemical analysis-Part VI: molecular luminescence spectroscopy' on page 233 (https://doi.org/10.1351/pac198456020231)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/delayed-fluorescence/"
}