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Understanding and Designing Thermally Activated Delayed Fluorescence Emitters: Beyond the Energy Gap Approximation

Lookup NU author(s): Dr Julien EngORCiD, Professor Thomas Penfold



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


In this article recent progress in the development of molecules exhibiting Thermally Activated Delayed Fluorescence (TADF) is discussed with a particular focus upon their application as emitters in highly efficient organic light emitting diodes (OLEDs). The key aspects controlling the desirable functional properties, e. g. fast intersystem crossing, high radiative rate and unity quantum yield, are introduced with a particular focus upon the competition between the key requirements needed to achieve high performance OLEDs. The design rules required for organic and metal organic materials are discussed, and the correlation between them outlined. Recent progress towards understanding the influence of the interaction between a molecule and its environment are explained as is the role of the mechanism for excited state formation in OLEDs. Finally, all of these aspects are combined to discuss the ability to implement high level design rules for achieving higher quality materials for commercial applications. This article highlights the significant progress that has been made in recent years, but also outlines the significant challenges which persist to achieve a full understanding of the TADF mechanism and improve the stability and performance of these materials.

Publication metadata

Author(s): Eng J, Penfold TJ

Publication type: Article

Publication status: Published

Journal: The Chemical Record

Year: 2020

Volume: 20

Issue: 8

Pages: 831-856

Print publication date: 01/08/2020

Online publication date: 08/04/2020

Acceptance date: 01/04/2020

Date deposited: 08/04/2020

ISSN (print): 1527-8999

ISSN (electronic): 1528-0691

Publisher: Wiley


DOI: 10.1002/tcr.202000013


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