Highly Charge Transport Thermally Activated Delayed Fluorescence Host Materials Based on Benzimidazole-Acridine Derivatives

2020 ◽  
Vol 20 (8) ◽  
pp. 5070-5074
Author(s):  
Ja Min Lee ◽  
Sae Won Lee ◽  
Young Sik Kim
Keyword(s):  
Dft Calculations ◽  
Charge Transport ◽  
Density Functional ◽  
Delayed Fluorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Host Molecules ◽  
Acridine Derivatives ◽  
Host Materials ◽  
Td Dft

We designed novel thermally activated delayed fluorescence (TADF) host molecules for blue electrophosphorescence by combining the electron acceptor benzimidazole (BI) unit and the electron donor acridine derivatives into a single molecular unit based on density functional theory (DFT). We obtained the energies of the first singlet (S1) and the first triplet (T1) excited states of the TADF materials by performing DFT and time-dependent DFT (TD-DFT) calculations to the ground state using dependence on charge transfer amounts for the optimal Hartree-Fock percentage in the exchange-correlation of TD-DFT. Using DFT and TD-DFT calculations, the large separation between the HOMO and LUMO caused a small difference in energy (ΔEST) between the S1 and T1 states. The host molecules retained high triplet energy and showed great potential for use in blue phosphorescent organic light-emitting diodes. The results showed that these molecules are promising TADF host materials because they have a low barrier to hole and electron injection, balanced charge transport for both holes and electrons, and a small ΔEST.

Noble Dibenzothiophene-Based Bipolar Hosts for Blue Organic Light-Emitting Diodes Using Thermally Activated Delayed Fluorescence

2020 ◽  
Vol 20 (11) ◽  
pp. 7191-7195
Author(s):  
JaMin Lee ◽  
Sae Won Lee ◽  
Young Sik Kim
Keyword(s):  
Dft Calculations ◽  
Light Emitting Diodes ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light ◽  
Host Materials ◽  
Td Dft

Novel thermally activated delayed fluorescence (TADF) host materials for blue electrophosphores-cence were designed by combining the electron acceptor dibenzothiophene (DBT) unit and the electron donor acridine derivatives into a single molecular unit by density functional theory (DFT). Depending on the optimal charge transfer, DFT and time-dependent DFT (TD-DFT) calculations for the ground state were performed to obtain the energy of the singlet (S1) and triplet (T1) excited states of the TADF material for Hartree-Fock percentage of TD-DFT. The sufficiently large separation between the HOMO and LUMO resulted in a small difference in energy (ΔEST) between the S1 and T1 states using DFT and TD-DFT calculations. The host molecules retained high triplet energy and showed great potential for use in blue organic light-emitting diodes (OLED). The results showed that these molecules are a good TADF host materials because they have a low barrier to hole and electron injection with a balanced charge transporting property for both holes and electrons, and a small ΔEST.

Finding the optimal exchange–correlation functional to describe the excited state properties of push–pull organic dyes designed for thermally activated delayed fluorescence

2020 ◽  
Vol 22 (28) ◽  
pp. 16387-16399 ◽  
Author(s):  
Tom Cardeynaels ◽  
Simon Paredis ◽  
Jasper Deckers ◽  
Sonny Brebels ◽  
Dirk Vanderzande ◽  
...  
Keyword(s):  
Excited State ◽  
Dft Calculations ◽  
Organic Dyes ◽  
Delayed Fluorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Exchange Correlation ◽  
Thermally Activated ◽  
Td Dft ◽  
Donor Acceptor

In view of designing organic dyes for TADF, TD-DFT calculations are performed on 10 prototypical donor-acceptor compounds and are benchmarked against riCC2 calculations, demonstrating that modified range-separated hybrids perform best.

Designing Noble Benzimidazole-Based Bipolar Hosts for Blue Organic Light-Emitting Diodes Using Thermally Activated Delayed Fluorescence Materials

2020 ◽  
Vol 20 (11) ◽  
pp. 7196-7200
Author(s):  
Ja Min Lee ◽  
Sae Won Lee ◽  
Young Sik Kim
Keyword(s):  
Dft Calculations ◽  
Molecular Orbital ◽  
Light Emitting Diodes ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light ◽  
Td Dft

We designed a novel thermally activated delayed fluorescence (TADF) host molecules for blue elec-trophosphorescence by combining the electron acceptor benzimidazole (BI) unit and the electron donor acridine derivatives into a single molecular unit based on density functional theory (DFT). We obtained the energies of the first singlet (S1) and the first triplet (T1) excited states of the TADF materials by performing DFT and time-dependent DFT (TD-DFT) calculations on the ground state using dependence on charge transfer amounts for the optimal Hartree–Fock percentage in the exchange-correlation of TD-DFT. The DFT and TD-DFT calculations showed that the large separation between the highest occupied molecular orbital and the lowest unoccupied molecular orbital caused a small difference in energy (ΔEST) between the S1 and T1 states. The host molecules retained a high triplet energy and demonstrated a great potential for use in blue phosphorescent organic light-emitting diodes. The results showed that these molecules are promising host materials for TADF OLEDs because they have a low barrier to hole and electron injection, a balanced charge transport for both holes and electrons, and a small ΔEST.

Polarity- and molecular orbital-engineered host materials for stable and efficient blue thermally activated delayed fluorescence

2020 ◽  
Author(s):  
Soo-Ghang Ihn ◽  
Daun Jeong ◽  
Eunsuk Kwon ◽  
Sangmo Kim ◽  
Yeon Sook Chung ◽  
...  
Keyword(s):  
Fold Increase ◽  
Molecular Geometry ◽  
Delayed Fluorescence ◽  
Full Potential ◽  
Charge Balance ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Host Molecules ◽  
Host Materials ◽  
Excited State Dipole Moment

Abstract To utilize thermally activated delayed fluorescence (TADF) technology for future displays, it is necessary to develop host materials that can harness the full potential of blue TADF emitters. We suggest an elaborative approach for designing host molecules for blue TADF devices with simultaneously improved efficiency and stability. We significantly enhanced the delayed fluorescence quantum yield by engineering the molecular geometry, polarity, and excited-state dipole moment of host molecules based on 3′,5-di(9H-carbazol-9-yl)-[1,1′-biphenyl]-3-carbonitrile. The engineerd hosts stabilized the charge-transfer excited states of TADF emitters, suppressed exciton quenching, and improved the charge balance in the emitting layer. Moreover, because the hosts are phosphine-oxide bond-free molecules, they are photochemically and electrochemically stable compared to bis[2-(diphenylphosphino)phenyl] ether oxide, the most popular high-polarity host. The devices employing the hosts exhibited a two-fold increase in external quantum efficiency and a 37-fold increase in operation lifetime compared to control devices with the same TADF emitter.

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 Solution-Processed OLEDs Based on Thermally Activated Delayed Fluorescence Copper(I) Complexes with Intraligand Charge-Transfer Excited State

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1125
Author(s):  
Teng Teng ◽  
Jinfan Xiong ◽  
Gang Cheng ◽  
Changjiang Zhou ◽  
Xialei Lv ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Density Functional ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Functional Theory ◽  
Solution Processed ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Wide Range

A new series of tetrahedral heteroleptic copper(I) complexes exhibiting efficient thermally-activated delayed fluorescence (TADF) in green to orange electromagnetic spectral regions has been developed by using D-A type N^N ligand and P^P ligands. Their structures, electrochemical, photophysical, and electroluminescence properties have been characterized. The complexes exhibit high photoluminescence quantum yields (PLQYs) of up to 0.71 at room temperature in doped film and the lifetimes are in a wide range of 4.3–24.1 μs. Density functional theory (DFT) calculations on the complexes reveal the lowest-lying intraligand charge-transfer excited states that are localized on the N^N ligands. Solution-processed organic light emitting diodes (OLEDs) based on one of the new emitters show a maximum external quantum efficiency (EQE) of 7.96%.

Potential thermally activated delayed fluorescence properties of a series of 2,3-dicyanopyrazine based compounds

2018 ◽  
Vol 3 (7) ◽  
Author(s):  
Ayşegül Gümüş ◽  
Selçuk Gümüş
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Delayed Fluorescence ◽  
Basis Sets ◽  
Functional Theory ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Structural And Electronic Properties ◽  
Donor Acceptor ◽  
Almost All

Abstract 2,3-Dicyanopyrazine based acceptor was combined with a series of well studied donors to obtain donor-acceptor type potential thermally activated delayed fluorescence emitters. Their structural and electronic properties were computed theoretically at the level of density functional theory and time dependent density functional theory with the application of two different hybrid functionals and various basis sets. Almost all of the designed structures were computed to have the potential of being TADF compounds since they possess very narrow singlet-triplet gaps. Indeed, acridine-pyrazine (9) derivative was calculated to be the best candidate for the purpose among them.

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