%0 Journal Article %1 Weissenseel_2021 %A Weissenseel, Sebastian %A Gottscholl, Andreas %A Bönnighausen, Rebecca %A Dyakonov, Vladimir %A Sperlich, Andreas %D 2021 %I American Association for the Advancement of Science (AAAS) %J Sci. Adv. %K c %N 47 %P eabj9961 %R 10.1126/sciadv.abj9961 %T Long-lived spin-polarized intermolecular exciplex states in thermally activated delayed fluorescence-based organic light-emitting diodes %U https://doi.org/10.1126%2Fsciadv.abj9961 %V 7 %X 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 T2* of 30 ns. Crucially, we obtain the characteristic triplet exciplex spin-lattice relaxation time T1 in the range of 50 μs, 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.

@article{Weissenseel_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 T2* of 30 ns. Crucially, we obtain the characteristic triplet exciplex spin-lattice relaxation time T1 in the range of 50 μs, 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.}, added-at = {2022-02-09T12:18:15.000+0100}, author = {Weissenseel, Sebastian and Gottscholl, Andreas and Bönnighausen, Rebecca and Dyakonov, Vladimir and Sperlich, Andreas}, biburl = {https://www.bibsonomy.org/bibtex/2a2b51057df602e3cdbf001f9c949d910/ctqmat}, day = 17, description = {Long-lived spin-polarized intermolecular exciplex states in thermally activated delayed fluorescence-based organic light-emitting diodes}, doi = {10.1126/sciadv.abj9961}, interhash = {c67af6672652153a3fdad22e5b78458f}, intrahash = {a2b51057df602e3cdbf001f9c949d910}, journal = {Sci. Adv.}, keywords = {c}, month = {11}, number = 47, pages = { eabj9961}, publisher = {American Association for the Advancement of Science ({AAAS})}, timestamp = {2023-10-17T12:27:32.000+0200}, title = {Long-lived spin-polarized intermolecular exciplex states in thermally activated delayed fluorescence-based organic light-emitting diodes}, url = {https://doi.org/10.1126%2Fsciadv.abj9961}, volume = 7, year = 2021 }