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Updated: Sep 6, 2025
07:44
Production and Characterization of Vacuum Deposited Organic Light Emitting Diodes
Published on: November 16, 2018
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Intersystem and Reverse-Intersystem Crossings in Organic Light-Emitting Diodes
Jai Singh1, U Shakeel1, David Ompong1
1College of Engineering, IT and Environment and Energy Resources Institute, Charles Darwin University, Darwin 0909, Northern Territory, Australia.
The Journal of Physical Chemistry Letters
|June 29, 2022
Summary
Thermally activated delayed fluorescence (TADF) rates depend on factors beyond atomic number, explaining its efficiency in metal-free organic light-emitting diodes. This work clarifies TADF mechanisms in these devices.
Area of Science:
- Organic electronics
- Photophysics
- Quantum chemistry
Background:
- Thermally activated delayed fluorescence (TADF) is crucial for efficient organic light-emitting diodes (OLEDs).
- Understanding the precise mechanisms governing TADF, particularly in metal-free systems, remains an active area of research.
Purpose of the Study:
- To derive and analyze the rates of reverse intersystem crossing (RISC) and TADF.
- To elucidate the factors influencing TADF efficiency, especially in metal-free organic solids.
Main Methods:
- Employed first-order perturbation theory.
- Utilized the exciton-spin-orbit-photon-molecular-vibration-interaction (ESOPMVI) operator to model RISC and TADF rates.
Main Results:
- The pre-exponential factor for TADF is not constant, depending on atomic number, exchange energy, and triplet excitonic Bohr radius.
- RISC rates are significantly enhanced (4-6 orders of magnitude) compared to intersystem crossing, diminishing the direct dependence on atomic number.
- TADF can be highly efficient in metal-free organic solids.
Conclusions:
- Provides a refined understanding of TADF mechanisms in metal-free organic light-emitting diodes.
- The derived theoretical framework supports recent experimental findings on efficient TADF in metal-free materials.
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