@article{WeissenseelGottschollBoennighausenetal.2021,
  author    = {Weissenseel, Sebastian and Gottscholl, Andreas and B{\"o}nnighausen, Rebecca and Dyakonov, Vladimir and Sperlich, Andreas},
  title     = {Long-lived spin-polarized intermolecular exciplex states in thermally activated delayed fluorescence-based organic light-emitting diodes},
  series = {Science Advances},
  volume    = {7},
  journal   = {Science Advances},
  number    = {47},
  doi       = {10.1126/sciadv.abj9961},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265508},
  year      = {2021},
  abstract  = {Spin-spin interactions in organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) are pivotal because radiative recombination is largely determined by triplet-to-singlet conversion, also called reverse intersystem crossing (RISC). To explore the underlying process, we apply a spin-resonance spectral hole-burning technique to probe electroluminescence. We find that the triplet exciplex states in OLEDs are highly spin-polarized and show that these states can be decoupled from the heterogeneous nuclear environment as a source of spin dephasing and can even be coherently manipulated on a spin-spin relaxation time scale T-2* of 30 ns. Crucially, we obtain the characteristic triplet exciplex spin-lattice relaxation time T-1 in the range of 50 mu s, which far exceeds the RISC time. We conclude that slow spin relaxation rather than RISC is an efficiency-limiting step for intermolecular donor:acceptor systems. Finding TADF emitters with faster spin relaxation will benefit this type of TADF OLEDs.},
  language  = {en}
}