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Lookup NU author(s): Shawana Ahmad, Dr Julien EngORCiD, Professor Thomas Penfold
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Multi-resonant Thermally Activated Delayed Fluorescent (MR-TADF) materials have received significant research interest owing to their potential use as emitters in high-performance Organic Light Emitting Diodes (OLEDs). Despite their advantages, including narrow emission spectra leading to high colour purity, several challenges remain in optimising the performance of these materials. One key issue is the typically long delayed fluorescence lifetime which arises from a large gap and weak coupling between the lowest lying singlet and triplet states. To develop high-performing materials, in silicodesign is an important step and consequently it is crucial to develop and deploy computational methods that accurately model their excited state properties. Previous studies have highlighted the importance of double excitations, which are not accounted for within the framework of Linear Response Time-Dependent Density Functional Theory (LR-TDDFT), contributing to the poor performance of this method for these materials. Consequently, in this work, we employ Mixed-Reference Spin-Flip Time-Dependent Density Functional Theory (MRSF-TDDFT) to calculate the properties of MR-TADF materials. Our findings indicate that this approach accurately predicts the excited state properties including the crucial E, the energy difference between the lowest singlet (S) and triplet (T) excited states. We further use this method to explore the excited state properties of systems designed to enhance the coupling between singlet and triplet states by increasing the density of states and enhancing spin–orbit coupling through metal perturbation. The results in this work sets the foundation for computationally efficient in silico development high-performing MR-TADF materials within the framework of MRSF-TDDFT.
Author(s): Ahmad S, Eng J, Penfold TJ
Publication type: Article
Publication status: Published
Journal: Organic Electronics
Year: 2024
Volume: 135
Print publication date: 01/12/2024
Online publication date: 12/09/2024
Acceptance date: 10/09/2024
Date deposited: 14/09/2024
ISSN (print): 1566-1199
ISSN (electronic): 1878-5530
Publisher: Elsevier BV
URL: https://doi.org/10.1016/j.orgel.2024.107138
DOI: 10.1016/j.orgel.2024.107138
Data Access Statement: Data will be made available on request.
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