Thermally activated triplet exciton release for highly efficient tri-mode organic afterglow.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32051404.
- Also identified by DOI 10.1038/s41467-020-14669-3 and PMC identifier 7016145.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Developing high-efficient afterglow from metal-free organic molecules remains a formidable challenge due to the intrinsically spin-forbidden phosphorescence emission nature of organic afterglow, and only a few examples exhibit afterglow efficiency over 10%. Here, we demonstrate that the organic afterglow can be enhanced dramatically by thermally activated processes to release the excitons on the stabilized triplet state (T<sub>1</sub><sup>*</sup>) to the lowest triplet state (T<sub>1</sub>) and to the singlet excited state (S<sub>1</sub>) for spin-allowed emission. Designed in a twisted donor-acceptor architecture with small singlet-triplet splitting energy and shallow exciton trapping depth, the thermally activated organic afterglow shows an efficiency up to 45%. This afterglow is an extraordinary tri-mode emission at room temperature from the radiative decays of S<sub>1</sub>, T<sub>1</sub>, and T<sub>1</sub><sup>*</sup>. With the highest afterglow efficiency reported so far, the tri-mode afterglow represents an important concept advance in designing high-efficient organic afterglow materials through facilitating thermally activated release of stabilized triplet excitons.