Triplet Harvesting with 100% Efficiency by Way of Thermally Activated Delayed Fluorescence in Charge Transfer OLED Emitters

Organic light-emitting diodes (OLEDs) have their performance limited by the number of emissive singlet states created upon charge recombination (25%). Recently, a novel strategy has been proposed, based on thermally activated up-conversion of triplet to singlet states, yielding delayed fluorescence (TADF), which greatly enhances electroluminescence. The energy barrier for this reverse intersystem crossing mechanism is proportional to the exchange energy (ΔEST ) between the singlet and triplet states; therefore, materials with intramolecular charge transfer (ICT) states, where it is known that the exchange energy is small, are perfect candidates. However, here it is shown that triplet states can be harvested…

• RS
  Royal Society
• EA
  Engineering and Physical Sciences Research Council

  Awards: EP/I006656/1, EP/K016164/1