@article{BunzmannKrugmannWeissenseeletal.2021,
  author    = {Bunzmann, Nikolai and Krugmann, Benjamin and Weissenseel, Sebastian and Kudriashova, Liudmila and Ivaniuk, Khrystyna and Stakhira, Pavlo and Cherpak, Vladyslav and Chapran, Marian and Grybauskaite-Kaminskiene, Gintare and Grazulevicius, Juozas Vidas and Dyakonov, Vladimir and Sperlich, Andreas},
  title     = {Spin- and Voltage-Dependent Emission from Intra- and Intermolecular TADF OLEDs},
  series = {Advanced Electronic Materials},
  volume    = {7},
  journal   = {Advanced Electronic Materials},
  number    = {3},
  doi       = {10.1002/aelm.202000702},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-224434},
  year      = {2021},
  abstract  = {Organic light emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) utilize molecular systems with a small energy splitting between singlet and triplet states. This can either be realized in intramolecular charge transfer states of molecules with near-orthogonal donor and acceptor moieties or in intermolecular exciplex states formed between a suitable combination of individual donor and acceptor materials. Here, 4,4′-(9H,9′H-[3,3′-bicarbazole]-9,9′-diyl)bis(3-(trifluoromethyl) benzonitrile) (pCNBCzoCF\(_{3}\)) is investigated, which shows intramolecular TADF but can also form exciplex states in combination with 4,4′,4′′-tris[phenyl(m-tolyl)amino]triphenylamine (m-MTDATA). Orange emitting exciplex-based OLEDs additionally generate a sky-blue emission from the intramolecular emitter with an intensity that can be voltage-controlled. Electroluminescence detected magnetic resonance (ELDMR) is applied to study the thermally activated spin-dependent triplet to singlet up-conversion in operating devices. Thereby, intermediate excited states involved in OLED operation can be investigated and the corresponding activation energy for both, intra- and intermolecular based TADF can be derived. Furthermore, a lower estimate is given for the extent of the triplet wavefunction to be ≥ 1.2 nm. Photoluminescence detected magnetic resonance (PLDMR) reveals the population of molecular triplets in optically excited thin films. Overall, the findings allow to draw a comprehensive picture of the spin-dependent emission from intra- and intermolecular TADF OLEDs.},
  language  = {en}
}