Projects per year
Abstract
Organic light-emitting diodes (OLEDs) are a revolutionary light-emitting display technology that has been successfully commercialized in mobile phones and TVs1,2. The injected charges form both singlet and triplet excitons, and for high efficiency it is important to enable triplets as well as singlets to emit light. Currently materials that harvest triplets by thermally activated delayed fluorescence (TADF) are a very active field of research as an alternative to phosphorescent emitters which usually employ heavy metal atoms3,4. Whilst excellent progress has been made, there is a severe decrease of efficiency as the drive current is increased, i.e. efficiency roll-off, in most TADF OLEDs. At present much of the literature suggests that efficiency roll-off should be reduced by minimising the energy difference between singlet and triplet excited states (EST) in order to maximise the rate of conversion of triplets to singlets via reverse intersystem crossing (kRISC) 5-20. We analyse the efficiency roll-off in a wide range of TADF OLEDs and find that neither of these parameters fully accounts for the reported efficiency roll-off. By considering the dynamic equilibrium between singlets and triplets in TADF materials, we propose a figure of merit (FOM) for materials design to reduce efficiency roll-off and discuss its correlation with reported data of TADF OLEDs. Our new FOM will guide the design and development of TADF materials that can reduce efficiency roll-off. It will help improve the efficiency of TADF OLEDs at realistic display operating conditions and expand the use of TADF materials to applications that require high brightness, such as lighting, augmented reality, and lasing.
Original language | English |
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Article number | 627 |
Pages (from-to) | 747–753 |
Number of pages | 14 |
Journal | Nature |
Volume | 627 |
Issue number | 8005 |
Early online date | 27 Mar 2024 |
DOIs | |
Publication status | Published - 28 Mar 2024 |
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Dive into the research topics of 'A figure of merit for efficiency roll-off in TADF-based organic LEDs'. Together they form a unique fingerprint.Projects
- 4 Finished
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EPSRC-JSPS Core-to-core Grant: EPSRC-JSPS Core-to-Core Grant Application
Samuel, I. D. W. (PI)
1/08/18 → 31/07/23
Project: Standard
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Chemistry EPSRC-JSPS: EPSRC-JSPS Core-to-Core Grant Application
Zysman-Colman, E. (PI)
1/08/18 → 31/01/24
Project: Standard
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TADF Emitters for OLEDs - Ifor Samuel: TADF Emitters for OLEDs
Samuel, I. D. W. (PI)
1/03/17 → 28/02/20
Project: Standard
Datasets
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A Figure of Merit for Thermally Activated Delayed Fluorescent Emitters for low Efficiency Roll-off in Organic Light-Emitting Diodes (dataset)
Diesing, S. (Creator), Zhang, L. (Creator), Zysman-Colman, E. (Creator) & Samuel, I. D. W. (Creator), University of St Andrews, 17 Apr 2024
DOI: 10.17630/d1439596-7eef-44ae-90cd-667b70588896
Dataset
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