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Enhancing Thermally Activated Delayed Fluorescence Through Structural And Energetic Flexibility: Theoretical Studies

Alhmoud, Dieaa H.

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TL04_1.pptx
5963.pdf

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https://hdl.handle.net/2142/116493

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Title
Enhancing Thermally Activated Delayed Fluorescence Through Structural And Energetic Flexibility: Theoretical Studies
Author(s)
Alhmoud, Dieaa H.
Contributor(s)
Lin, Zhou
Issue Date
2022-06-21
Keyword(s)
Theory and Computation
Abstract
\begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.20]{Abstract.eps} \end{wrapfigure} Thermally activated delayed fluorescence (TADF) is one of the most promising routes to enhance the luminescent efficiency of an organic light-emitting diode (OLED) device by converting a non-emissive triplet exciton (T$_1$) back to an emissive singlet configuration (S$_1$) through reverse intersystem crossing (RISC) before it fluoresces back to the ground state (S$_0$). However, the TADF rate is generally restricted if only the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are involved. This is due to the conflict between a fast RISC rate between S$_1$ and T$_1$ (which requires a small HOMO--LUMO overlap), and a large transition dipole moment ($\mu_\text{T}$) between S$_1$ and S$_0$ (which requires a large HOMO--LUMO overlap).\footnote{A. Endo et al., {\it Appl. Phys. Lett.} {\bf 2011}, 98, 083302.} In the present study, we proposed two solutions to enhance the overall fluorescent rate: an inclusion of higher-lying singlet and triplet states (S$_{n\ge2}$ and T$_{n\ge2}$) in ISC--RISC routes to avoid the trade-off, and a fluxional molecular conformation to sample a broad range of HOMO--LUMO overlap. We provided a proof-of-concept for our solutions based on computational modeling of sample di-tert-butyl carbazole derivatives with the pyrazine or dipyrazine substituents (DTCz-Pz or DTCz-Pz), using a combination of density functional theory (DFT) and molecular dynamics (MD). Our study will provide a computational and quantitative strategy for the design of new TADF emitters with maximum luminescent efficiency.
Publisher
International Symposium on Molecular Spectroscopy
Type of Resource
text
Genre of Resource
Conference Paper / Presentation
Language
eng
Handle URL
https://hdl.handle.net/2142/116493
DOI
https://doi.org/10.15278/isms.2022.TL04
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Copyright 2022 held by the authors

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Abstracts & Presentations - 2022 International Symposium on Molecular Spectroscopy PRIMARY