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Long-lived spin-polarized intermolecular exciplex states in thermally activated delayed fluorescence-based organic light-emitting diodes
Please always quote using this URN: urn:nbn:de:bvb:20-opus-265508
- 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 nuclearSpin-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.…
Author: | Sebastian WeissenseelORCiD, Andreas GottschollORCiD, Rebecca Bönnighausen, Vladimir DyakonovORCiD, Andreas SperlichORCiD |
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URN: | urn:nbn:de:bvb:20-opus-265508 |
Document Type: | Journal article |
Faculties: | Fakultät für Physik und Astronomie / Physikalisches Institut |
Language: | English |
Parent Title (English): | Science Advances |
Year of Completion: | 2021 |
Volume: | 7 |
Issue: | 47 |
Article Number: | eabj9961 |
Source: | Science Advances (2021) 7:48, eabj9961. https://doi.org/10.1126/sciadv.abj9961 |
DOI: | https://doi.org/10.1126/sciadv.abj9961 |
Dewey Decimal Classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
Tag: | absorption; charge separation; detected magnetic-resonance; emission; hole; phosphorescence; polaron delocalization; population oscillations; singlet; tryptophan |
Release Date: | 2022/04/29 |
Collections: | Open-Access-Publikationsfonds / Förderzeitraum 2021 |
Licence (German): | CC BY-NC: Creative-Commons-Lizenz: Namensnennung, Nicht kommerziell 4.0 International |