scholarly journals Enhancing Thermally Activated Delayed Fluorescence by Fine-Tuning the Dendron Donor Strength

2022 ◽  
Author(s):  
Eimantas Duda ◽  
David Hall ◽  
Sergey Bagnich ◽  
Cameron L. Carpenter-Warren ◽  
Rishabh Saxena ◽  
...  
Keyword(s):  
Delayed Fluorescence ◽  
Fine Tuning ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated

scholarly journals Using the Mechanical Bond to Tune the Performance of a Thermally Activated Delayed Fluorescence Emitter

2021 ◽  
Author(s):  
P Rajamalli ◽  
Federica Rizzi ◽  
Wenbo Li ◽  
Michael Jinks ◽  
Abhishek Gupta ◽  
...  
Keyword(s):  
Weak Interactions ◽  
Photophysical Properties ◽  
Energy Difference ◽  
Delayed Fluorescence ◽  
Fine Tuning ◽  
Triplet States ◽  
Thermally Activated Delayed Fluorescence ◽  
X Ray Crystallography ◽  
Thermally Activated ◽  
Mechanical Bond

We report the characterization of rotaxanes based on a carbazole–benzophenone thermally activated delayed fluorescence luminophore. We find that the mechanical bond leads to an improvement in key photophysical properties of the emitter, notably an increase in photoluminescence quantum yield and a decrease in the energy difference between singlet and triplet states, as well as fine tuning of the emission wavelength, a feat that is difficult to achieve when using covalently bound substituents. Computational simulations, supported by X-ray crystallography, suggest that this tuning of properties occurs due to weak interactions between the axle and the macrocycle that are enforced by the mechanical bond. This work highlights the benefits of using the mechanical bond to refine existing luminophores, providing a new avenue for emitter optimization that can ultimately increase the performance of these molecules.

Thermally activated delayed fluorescence emitters with a m,m-di-tert-butyl-carbazolyl benzoylpyridine core achieving extremely high blue electroluminescence efficiencies

2017 ◽  
Vol 5 (11) ◽  
pp. 2919-2926 ◽  
Author(s):  
Pachaiyappan Rajamalli ◽  
Vasudevan Thangaraji ◽  
Natarajan Senthilkumar ◽  
Chen-Cheng Ren-Wu ◽  
Hao-Wu Lin ◽  
...  
Keyword(s):  
High Performance ◽  
Delayed Fluorescence ◽  
Fine Tuning ◽  
Thermally Activated Delayed Fluorescence ◽  
Tert Butyl ◽  
Thermally Activated

High performance blue OLEDs with maximum EQEs over 28% are achieved from TADF emitters by fine tuning the acceptor unit.

scholarly journals Enhancing thermally activated delayed fluorescence by fine-tuning the dendron donor strength

2021 ◽  
Author(s):  
Anna Köhler ◽  
Eimantas Duda ◽  
David Hall ◽  
Sergey Bagnich ◽  
Cameron L. Carpenter-Warren ◽  
...  
Keyword(s):  
Delayed Fluorescence ◽  
Fine Tuning ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated

scholarly journals Using the Mechanical Bond to Tune the Performance of a Thermally Activated Delayed Fluorescence Emitter

2021 ◽  
Author(s):  
P Rajamalli ◽  
Federica Rizzi ◽  
Wenbo Li ◽  
Michael Jinks ◽  
Abhishek Gupta ◽  
...  
Keyword(s):  
Weak Interactions ◽  
Photophysical Properties ◽  
Energy Difference ◽  
Delayed Fluorescence ◽  
Fine Tuning ◽  
Triplet States ◽  
Thermally Activated Delayed Fluorescence ◽  
X Ray Crystallography ◽  
Thermally Activated ◽  
Mechanical Bond

We report the characterization of rotaxanes based on a carbazole–benzophenone thermally activated delayed fluorescence luminophore. We find that the mechanical bond leads to an improvement in key photophysical properties of the emitter, notably an increase in photoluminescence quantum yield and a decrease in the energy difference between singlet and triplet states, as well as fine tuning of the emission wavelength, a feat that is difficult to achieve when using covalently bound substituents. Computational simulations, supported by X-ray crystallography, suggest that this tuning of properties occurs due to weak interactions between the axle and the macrocycle that are enforced by the mechanical bond. This work highlights the benefits of using the mechanical bond to refine existing luminophores, providing a new avenue for emitter optimization that can ultimately increase the performance of these molecules.

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>

New hole transport styrene polymers bearing highly π-extended conjugated side-chain moieties for high-performance solution-processable thermally activated delayed fluorescence OLEDs

2021 ◽  
Vol 12 (11) ◽  
pp. 1692-1699
Author(s):  
Ji Hye Lee ◽  
Jinhyo Hwang ◽  
Chai Won Kim ◽  
Amit Kumar Harit ◽  
Han Young Woo ◽  
...  
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Delayed Fluorescence ◽  
Hole Transport ◽  
Side Chain ◽  
Solution Processed ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Turn On ◽  
Solution Processable

New polystyrene-based polymers with high π-extended hole transport pendants were synthesized to obtain a low turn-on voltage and high efficiency in solution-processed green TADF-OLEDs.

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