scholarly journals Constructing Narrowband Thermally Activated Delayed Fluorescence Materials with Emission Maxima Beyond 560 nm Based on Frontier Molecular Orbital Engineering

2021 ◽  
Author(s):  
Xinliang Cai ◽  
Yincai Xu ◽  
Qingyang Wang ◽  
Chenglong Li ◽  
Yue Wang
Keyword(s):  
Molecular Orbital ◽  
Wavelength Region ◽  
Coupling Reaction ◽  
Spatial Separation ◽  
Delayed Fluorescence ◽  
Frontier Molecular Orbital ◽  
Esterification Reaction ◽  
Thermally Activated Delayed Fluorescence ◽  
Suzuki Coupling Reaction ◽  
Thermally Activated

<p>The development of purely organic materials with narrowband emission in long wavelength region beyond 560 nm still remains a great challenge. Herein, we present a modification approach of multiple resonance (MR) skeleton with electron donor based on frontier molecular orbital engineering (FMOE), resulting in significant red-shift emission of target molecules. Subsequently, the parent MR skeleton is functionalized by boron esterification reaction and changed into a universal building block, namely, the key intermediate BN-Bpin, for molecular structure optimizations. BN-Bpin has been employed to construct a series of highly efficient thermally activated delayed fluorescence (TADF) materials with high color purity through one-step Suzuki coupling reaction. The target molecule perfectly integrates the inherent advantages of MR skeleton and spatial separation typical donor–acceptor (D–A) structure. The results demonstrate that the ingenious modulation of the acceptor is an effective approach to achieve bathochromic emission and narrowband emission simultaneously.</p>

scholarly journals Constructing Narrowband Thermally Activated Delayed Fluorescence Materials with Emission Maxima Beyond 560 nm Based on Frontier Molecular Orbital Engineering

2021 ◽  
Author(s):  
Xinliang Cai ◽  
Yincai Xu ◽  
Qingyang Wang ◽  
Chenglong Li ◽  
Yue Wang
Keyword(s):  
Molecular Orbital ◽  
Wavelength Region ◽  
Coupling Reaction ◽  
Spatial Separation ◽  
Delayed Fluorescence ◽  
Frontier Molecular Orbital ◽  
Esterification Reaction ◽  
Thermally Activated Delayed Fluorescence ◽  
Suzuki Coupling Reaction ◽  
Thermally Activated

<p>The development of purely organic materials with narrowband emission in long wavelength region beyond 560 nm still remains a great challenge. Herein, we present a modification approach of multiple resonance (MR) skeleton with electron donor based on frontier molecular orbital engineering (FMOE), resulting in significant red-shift emission of target molecules. Subsequently, the parent MR skeleton is functionalized by boron esterification reaction and changed into a universal building block, namely, the key intermediate BN-Bpin, for molecular structure optimizations. BN-Bpin has been employed to construct a series of highly efficient thermally activated delayed fluorescence (TADF) materials with high color purity through one-step Suzuki coupling reaction. The target molecule perfectly integrates the inherent advantages of MR skeleton and spatial separation typical donor–acceptor (D–A) structure. The results demonstrate that the ingenious modulation of the acceptor is an effective approach to achieve bathochromic emission and narrowband emission simultaneously.</p>

Lowest unoccupied molecular orbital managing function of CN-substituted dibenzofuran in high triplet energy hosts for blue thermally-activated delayed fluorescent organic light-emitting diodes

2021 ◽  
Author(s):  
Sung Yong Byun ◽  
Kyung Hyung Lee ◽  
Jun Yeob Lee
Keyword(s):  
Molecular Orbital ◽  
Light Emitting Diodes ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Triplet Energy ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light ◽  
Lowest Unoccupied Molecular Orbital

The effect of lowest unoccupied molecular orbital (LUMO) management of high triplet energy electron transport type hosts on the device performance of blue thermally-activated delayed fluorescence (TADF) organic light-emitting diodes...

scholarly journals Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

2018 ◽  
Vol 14 ◽  
pp. 282-308 ◽  
Author(s):  
Thanh-Tuân Bui ◽  
Fabrice Goubard ◽  
Malika Ibrahim-Ouali ◽  
Didier Gigmes ◽  
Frédéric Dumur
Keyword(s):  
Molecular Orbital ◽  
Light Emitting Diodes ◽  
Molecular Design ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light ◽  
Recent Advances

The design of highly emissive and stable blue emitters for organic light emitting diodes (OLEDs) is still a challenge, justifying the intense research activity of the scientific community in this field. Recently, a great deal of interest has been devoted to the elaboration of emitters exhibiting a thermally activated delayed fluorescence (TADF). By a specific molecular design consisting into a minimal overlap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) due to a spatial separation of the electron-donating and the electron-releasing parts, luminescent materials exhibiting small S1–T1 energy splitting could be obtained, enabling to thermally upconvert the electrons from the triplet to the singlet excited states by reverse intersystem crossing (RISC). By harvesting both singlet and triplet excitons for light emission, OLEDs competing and sometimes overcoming the performance of phosphorescence-based OLEDs could be fabricated, justifying the interest for this new family of materials massively popularized by Chihaya Adachi since 2012. In this review, we proposed to focus on the recent advances in the molecular design of blue TADF emitters for OLEDs during the last few years.

scholarly journals Red Thermally Activated Delayed Fluorescence in Dibenzopyridoquinoxaline-Based Nanoaggregates

2021 ◽  
Author(s):  
Subhadeep Das ◽  
Subhankar Kundu ◽  
Bahadur Sk ◽  
Madhurima Sarkar ◽  
Abhijit Patra
Keyword(s):  
Stokes Shift ◽  
Wavelength Region ◽  
Delayed Fluorescence ◽  
High Rate ◽  
Homogeneous Distribution ◽  
Aqueous Environment ◽  
Fluorescent Nanoparticles ◽  
Water Mixture ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated

All-organic thermally activated delayed fluorescence (TADF) materials have emerged as potential candidates for optoelectronic devices and biomedical applications. However, the development of organic TADF probes with strong emission in the longer wavelength region (> 600 nm) remains a challenge. Strong π-conjugated rigid acceptor cores substituted with multiple donor units can be a viable design strategy to obtain red TADF probes. Herein, 3,6 di-t-butyl carbazole substituted to dibenzopyridoquinoxaline acceptor core resulted in T-shaped donor-acceptor-donor compound, PQACz-T, exhibiting red thermally activated delayed fluorescence in polymer embedded thin films. Further, PQACz-T self-assembled to molecular nanoaggregates of diverse size and shape in THF-water mixture showing bright red emission along with delayed fluorescence even in an aqueous environment. The self-assembly and the excited-state properties of PQACz-T were compared with the nonalkylated analogue, PQCz-T. The delayed fluorescence in nanoaggregates was attributed to the high rate of reverse intersystem crossing. Moreover, an aqueous dispersion of the smaller-sized, homogeneous distribution of fluorescent nanoparticles was fabricated upon encapsulating PQACz-T in a triblock copolymer, F-127. Cytocompatible polymer encapsulated PQACz-T nanoparticles with large Stokes shift, excellent photostability were demonstrated for the specific imaging of lipid droplets in HeLa cells.

Theoretical Study on Benzazole Derivatives for Use in Blue Thermally Activated Delayed Fluorescence Emitters

2015 ◽  
Vol 15 (10) ◽  
pp. 7819-7822 ◽  
Author(s):  
Dong Yuel Kwon ◽  
Geon Hyeong Lee ◽  
Young Sik Kim
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Light Emitting Diode ◽  
Energy Difference ◽  
Delayed Fluorescence ◽  
Functional Theory ◽  
Thermally Activated Delayed Fluorescence ◽  
Organic Light Emitting Diode ◽  
Thermally Activated

Four novel thermally activated delayed fluorescence (TADF) materials with 9,10-dihydro-9,9- dimethylacridine (DMAC) and phenylindolo(2,3-a)carbazole (PIC) as electron donors and benzazole derivatives (BO, and BT) as electron acceptors (DMAC-BO, DMAC-BT, PIC-BO, and PIC-BT) were designed and theoretically investigated for use as a blue organic light emitting diode (OLED) emitter. Using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations, we calculated the electron distribution of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), and the energy of the lowest singlet (S1) and the lowest triplet (T1) excited states. All the dyes had a small spatial overlap between the HOMO and LUMO because of the relatively large dihedral angle between the phenyl ring and the acceptor moiety. In terms of the energy difference (ΔEST) between the S1 state and the T1 state, DMAC-BO and DMAC-BT showed the small ΔEST (0.18 eV and 0.21 eV, respectively). However, PIC-BO and PIC-BT showed the large ΔEST (0.62 eV and 0.61 eV, respectively). Among the TADF materials, we showed that DMAC-BO would have the best TADF properties in terms of small ΔEST and blue OLED emitters

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.

scholarly journals Attaching Strong Auxiliary Acceptor onto B-N-Containing Multiple Resonance Framework and Achieving Highly Efficient Electroluminescence with Ultrahigh Color Purity

2021 ◽  
Author(s):  
Chenglong Li ◽  
Yue Wang ◽  
Yincai Xu ◽  
Zhiqaing Li ◽  
Jiaxuan Wang ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Bathochromic Shift ◽  
Wavelength Region ◽  
Coupling Reaction ◽  
Green Emission ◽  
Delayed Fluorescence ◽  
Color Purity ◽  
Suzuki Coupling Reaction ◽  
Multiple Resonance ◽  
Low Efficiency

<p>The development and enrichment of organic materials with narrowband emission in longer wavelength region beyond 515 nm still remains a great challenge. Herein, a series of unique narrowband green thermally activated delayed fluorescence (TADF) emitters has been constructed based on a synthetic strategy by localized attachment of acceptor onto B-N-containing multiple resonance (MR) framework. The precise modulation of acceptor is an ingenious approach for achieving bathochromic shift and narrowband emission, simultaneously. Furthermore, an important synthetic methodology has been proposed to functionalize MR skeleton and generate a universal building block, which can be utilized to construct multifarious TADF materials with ultrahigh color purity through a simple one-step Suzuki coupling reaction. The DtCzB-TPTRZ-based organic light-emitting diode (OLED) exhibits pure green emission with Commission Internationale de L’Eclairage (CIE) coordinates of (0.23, 0.68), and achieves remarkable maximum external quantum efficiency (EQE) of 30.6% with low efficiency roll-off.</p>

The effect of frontier orbital distribution of the core structure on the photophysics and device performances of thermally activated delayed fluorescence emitters

2019 ◽  
Vol 7 (25) ◽  
pp. 7760-7767 ◽  
Author(s):  
Mina Jung ◽  
Kyung Hyung Lee ◽  
Wan Pyo Hong ◽  
Jun Yeob Lee
Keyword(s):  
Molecular Orbital ◽  
Delayed Fluorescence ◽  
Core Structure ◽  
Frontier Orbital ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
The Core ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

The effect of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) distribution of the core structure on the thermally activated delayed fluorescence (TADF) behavior of the TADF emitters was investigated.

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