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>

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>

scholarly journals Characterization of Excited States in a Multiple-Resonance-Type Thermally Activated Delayed Fluorescence Molecule Using Time-resolved Infrared Spectroscopy

2021 ◽  
Author(s):  
Yuushi Shimoda ◽  
Masaki Saigo ◽  
Tomohiro Ryu ◽  
Takumi Ehara ◽  
Kiyoshi Miyata ◽  
...  
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Potential Surfaces ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Multiple Resonance ◽  
Time Resolved Infrared Spectroscopy

We have investigated the correlation between the photophysical properties and the excited-state detailed characteristics in a multiple-resonance-type thermally activated delayed fluorescence (TADF) molecule, DABNA-1, using time-resolved infrared vibrational spectroscopy. In comparison of the distinctive vibrational spectra in the fingerprint region, 1000 - 1700 cm<sup>-1</sup>, to the simulated spectra by density functional theory calculations, we found the best calculation condition. On the basis of the calculations, we determined the excited-state geometries and molecular orbitals of the lowest excited singlet (S<sub>1</sub>) and triplet (T<sub>1</sub>) states as well as the ground state (S<sub>0</sub>). We revealed that the similarity of the potential surfaces between T<sub>1</sub> and S<sub>0</sub> suppresses the nonradiative decay and causes the high fluorescence quantum yield via TADF process.

scholarly journals Characterization of Excited States in a Multiple-Resonance-Type Thermally Activated Delayed Fluorescence Molecule Using Time-resolved Infrared Spectroscopy

2021 ◽  
Author(s):  
Yuushi Shimoda ◽  
Masaki Saigo ◽  
Tomohiro Ryu ◽  
Takumi Ehara ◽  
Kiyoshi Miyata ◽  
...  
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Potential Surfaces ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Multiple Resonance ◽  
Time Resolved Infrared Spectroscopy

We have investigated the correlation between the photophysical properties and the excited-state detailed characteristics in a multiple-resonance-type thermally activated delayed fluorescence (TADF) molecule, DABNA-1, using time-resolved infrared vibrational spectroscopy. In comparison of the distinctive vibrational spectra in the fingerprint region, 1000 - 1700 cm<sup>-1</sup>, to the simulated spectra by density functional theory calculations, we found the best calculation condition. On the basis of the calculations, we determined the excited-state geometries and molecular orbitals of the lowest excited singlet (S<sub>1</sub>) and triplet (T<sub>1</sub>) states as well as the ground state (S<sub>0</sub>). We revealed that the similarity of the potential surfaces between T<sub>1</sub> and S<sub>0</sub> suppresses the nonradiative decay and causes the high fluorescence quantum yield via TADF process.

scholarly journals Thermally activated delayed fluorescence vs. room temperature phosphorescence by conformation control of organic single molecules

2019 ◽  
Vol 7 (22) ◽  
pp. 6616-6621 ◽  
Author(s):  
Przemyslaw Data ◽  
Masato Okazaki ◽  
Satoshi Minakata ◽  
Youhei Takeda
Keyword(s):  
Room Temperature ◽  
Single Molecules ◽  
Delayed Fluorescence ◽  
Room Temperature Phosphorescence ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Molecular Conformations ◽  
Thermally Activated ◽  
Luminescent Compound

The time-resolved photophysical analysis of a multi-color-changing mechanochromic luminescent compound has been disclosed, which reveals distinct different emission paths to boost TADF and RTP of the emitter depending on its molecular conformations.

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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