The key role of acceptor moieties on the structural and the electronic properties of thermally activated delayed fluorescence emitters in excited states: A computational study

2020 ◽  
Vol 78 ◽  
pp. 105595 ◽  
Author(s):  
Sunwoo Kang ◽  
Sang Ho Jeon ◽  
Young Mi Cho ◽  
Yong Jo Kim ◽  
Taekyung Kim ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Excited States ◽  
Computational Study ◽  
Delayed Fluorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated

scholarly journals Revisiting the Role of Charge Transfer and Local Excitations in Thermally Activated Delayed Fluorescence

2022 ◽  
Author(s):  
Leonardo Evaristo de Sousa ◽  
Piotr de Silva
Keyword(s):  
Charge Transfer ◽  
Excited States ◽  
Delayed Fluorescence ◽  
Equilibrium Geometry ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Model Hamiltonian ◽  
The Difference ◽  
Triplet Excitons

Thermally activated delayed fluorescence (TADF) is a phenomenon that relies on the upconversion of triplet excitons to singlet excitons by means of reverse intersystem crossing (rISC). It has been shown both experimentally and theoretically that the TADF mechanism depends on the interplay between charge transfer and local excitations. However, the difference between the diabatic and adiabatic character of the involved excited states is rarely discussed in the literature. Here, we develop a diabatization procedure to implement a 4-state model Hamiltonian to a set of TADF molecules. We provide physical interpretation for the Hamiltonian elements and show their dependence on the electronic state of the equilibrium geometry. We also demonstrate how vibrations affect TADF efficiency by modifying the diabatic decomposition of the molecule. Finally, we provide a simple model that connects the diabatic Hamiltonian to the electronic properties relevant to TADF and show how such relationship translates into different optimization strategies for rISC, fluorescence and overall TADF performance.

scholarly journals The Role of Local Triplet Excited States and D-A Relative Orientation in Thermally Activated Delayed Fluorescence: Photophysics and Devices

2016 ◽  
Vol 3 (12) ◽  
pp. 1600080 ◽  
Author(s):  
Fernando B. Dias ◽  
Jose Santos ◽  
David R. Graves ◽  
Przemyslaw Data ◽  
Roberto S. Nobuyasu ◽  
...  
Keyword(s):  
Excited States ◽  
Delayed Fluorescence ◽  
Relative Orientation ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Triplet Excited States

Solvent Dependence of Structural Dynamics and Spin-flip Processes in 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (ortho-3CzBN)

2020 ◽  
Author(s):  
Masaki Saigo ◽  
Kiyoshi Miyata ◽  
Hajime Nakanotani ◽  
Chihaya Adachi ◽  
Ken Onda
Keyword(s):  
Dft Calculations ◽  
Excited States ◽  
Structural Changes ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Solvent Dependence ◽  
Acetonitrile Solutions

We have investigated the solvent-dependence of structural changes along with intersystem crossing of a thermally activated delayed fluorescence (TADF) molecule, 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (o-3CzBN), in toluene, tetrahydrofuran, and acetonitrile solutions using time-resolved infrared (TR-IR) spectroscopy and DFT calculations. We found that the geometries of the S1 and T1 states are very similar in all solvents though the photophysical properties mostly depend on the solvent. In addition, the time-dependent DFT calculations based on these geometries suggested that the thermally activated delayed fluorescence process of o-3CzBN is governed more by the higher-lying excited states than by the structural changes in the excited states.<br>

The Role of Electron–Hole Separation in Thermally Activated Delayed Fluorescence in Donor–Acceptor Blends

2015 ◽  
Vol 119 (45) ◽  
pp. 25591-25597 ◽  
Author(s):  
Eric Hontz ◽  
Wendi Chang ◽  
Daniel N. Congreve ◽  
Vladimir Bulović ◽  
Marc A. Baldo ◽  
...  
Keyword(s):  
Delayed Fluorescence ◽  
Electron Hole ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Donor Acceptor

scholarly journals Exploiting trifluoromethyl substituents for tuning orbital character of singlet and triplet states to increase the rate of thermally activated delayed fluorescence

2020 ◽  
Vol 4 (12) ◽  
pp. 3602-3615 ◽  
Author(s):  
Jonathan S. Ward ◽  
Andrew Danos ◽  
Patrycja Stachelek ◽  
Mark A. Fox ◽  
Andrei S. Batsanov ◽  
...  
Keyword(s):  
Excited States ◽  
Organic Molecules ◽  
Delayed Fluorescence ◽  
Triplet States ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Conjugated Organic Molecules ◽  
Singlet And Triplet States ◽  
Triplet Excited States ◽  
Orbital Character

This work shows that trifluoromethyl (CF3) substituents can be used to increase the rate of thermally activated delayed fluorescence (TADF) in conjugated organic molecules by tuning the excitonic character of the singlet and triplet excited states.

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