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Cho HH, Congrave DG, Gillett AJ, Montanaro S, Francis HE, Riesgo-Gonzalez V, Ye J, Chowdury R, Zeng W, Etherington MK, Royakkers J, Millington O, Bond AD, Plasser F, Frost JM, Grey CP, Rao A, Friend RH, Greenham NC, Bronstein H. Suppression of Dexter transfer by covalent encapsulation for efficient matrix-free narrowband deep blue hyperfluorescent OLEDs. Nat Mater 2024; 23:519-526. [PMID: 38480865 PMCID: PMC10990937 DOI: 10.1038/s41563-024-01812-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 01/18/2024] [Indexed: 03/21/2024]
Abstract
Hyperfluorescence shows great promise for the next generation of commercially feasible blue organic light-emitting diodes, for which eliminating the Dexter transfer to terminal emitter triplet states is key to efficiency and stability. Current devices rely on high-gap matrices to prevent Dexter transfer, which unfortunately leads to overly complex devices from a fabrication standpoint. Here we introduce a molecular design where ultranarrowband blue emitters are covalently encapsulated by insulating alkylene straps. Organic light-emitting diodes with simple emissive layers consisting of pristine thermally activated delayed fluorescence hosts doped with encapsulated terminal emitters exhibit negligible external quantum efficiency drops compared with non-doped devices, enabling a maximum external quantum efficiency of 21.5%. To explain the high efficiency in the absence of high-gap matrices, we turn to transient absorption spectroscopy. It is directly observed that Dexter transfer from a pristine thermally activated delayed fluorescence sensitizer host can be substantially reduced by an encapsulated terminal emitter, opening the door to highly efficient 'matrix-free' blue hyperfluorescence.
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Affiliation(s)
- Hwan-Hee Cho
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | - Daniel G Congrave
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK.
| | | | - Stephanie Montanaro
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Haydn E Francis
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
- The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot, UK
| | - Víctor Riesgo-Gonzalez
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
- The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot, UK
| | - Junzhi Ye
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | | | - Weixuan Zeng
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Marc K Etherington
- Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Ellison Place, Newcastle upon Tyne, UK
| | - Jeroen Royakkers
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Oliver Millington
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Andrew D Bond
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Felix Plasser
- Department of Chemistry, Loughborough University, Loughborough, UK
| | | | - Clare P Grey
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
- The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot, UK
| | - Akshay Rao
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | | | - Neil C Greenham
- Cavendish Laboratory, University of Cambridge, Cambridge, UK.
| | - Hugo Bronstein
- Cavendish Laboratory, University of Cambridge, Cambridge, UK.
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK.
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