scholarly journals Balancing charge-transfer strength and triplet states for deep-blue thermally activated delayed fluorescence with an unconventional electron rich dibenzothiophene acceptor

2019 ◽  
Vol 7 (42) ◽  
pp. 13224-13234 ◽  
Author(s):  
Rongjuan Huang ◽  
Nadzeya A. Kukhta ◽  
Jonathan S. Ward ◽  
Andrew Danos ◽  
Andrei S. Batsanov ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Molecular Design ◽  
Delayed Fluorescence ◽  
Triplet States ◽  
Thermally Activated Delayed Fluorescence ◽  
Emission Properties ◽  
Thermally Activated ◽  
Deep Blue ◽  
Blue Emitters

Manipulation of the emission properties of deep-blue emitters exhibiting thermally activated delayed fluorescence (TADF) through molecular design is reported.

Through-Space Charge Transfer Dendrimers Employing Oxygen-Bridged Triarylboron Acceptors for Efficient Deep-Blue Electroluminescence

2021 ◽  
Author(s):  
Baoyun Du ◽  
Xingdong Wang ◽  
Fan Chen ◽  
Qingqing Yang ◽  
Shiyang Shao ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Space Charge ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
State Of The Art ◽  
Delayed Fluorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Deep Blue

Though-space charge transfer dendrimers consisting of dendritic triacridan donors and oxygen-bridged triarylboron acceptors are demonstrated to exhibit deep-blue thermally activated delayed fluorescence with state-of-the-art external quantum efficiency of 14.6% for...

scholarly journals Extremely condensing triplet states of DPEPO-type hosts through constitutional isomerization for high-efficiency deep-blue thermally activated delayed fluorescence diodes

2016 ◽  
Vol 7 (4) ◽  
pp. 2870-2882 ◽  
Author(s):  
Jing Zhang ◽  
Dongxue Ding ◽  
Ying Wei ◽  
Hui Xu
Keyword(s):  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
High Efficiency ◽  
State Of The Art ◽  
Delayed Fluorescence ◽  
Triplet States ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Deep Blue ◽  
Art Performance

An asymmetric constitutional isomer of the thermally activated delayed fluorescence (TADF) host DPEPO, named 24′DPEPO, endowed deep-blue TADF diodes with state-of-the-art performance, including external quantum efficiency beyond 20%.

scholarly journals Molecular Design Realizing Very Fast Reverse Intersystem Crossing in Purely Organic Emitter

2019 ◽  
Author(s):  
yoshimasa wada ◽  
Hiromichi Nakagawa ◽  
Soma Matsumoto ◽  
Yasuaki Wakisaka ◽  
Hironori Kaji
Keyword(s):  
Energy Gap ◽  
Molecular Design ◽  
Delayed Fluorescence ◽  
Intersystem Crossing ◽  
Triplet States ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Donor And Acceptor ◽  
Spin Inversion

Reverse intersystem crossing (RISC), originally considered forbidden in purely organic materials, has been recently enabled by minimizing the energy gap between the lowest singlet excited state (S<sub>1</sub>) and lowest triplet state (T<sub>1</sub>) in thermally activated delayed fluorescence (TADF) systems. However, direct spin-inversion between S<sub>1</sub> and T<sub>1</sub> is still inefficient when both states are of the same charge transfer (CT) nature (i.e. <sup>1</sup>CT and <sup>3</sup>CT, respectively). Intervention of locally excited triplet states (<sup>3</sup>LE) between <sup>1</sup>CT and <sup>3</sup>CT is expected to trigger fast spin-flip. Here, we report on the systematic-design of the ideal TADF molecules with near-degenerate <sup>1</sup>CT, <sup>3</sup>CT and <sup>3</sup>LE states by controlling the through-space distance between the donor and acceptor segments in a molecule with tilted intersegment angles. The new system realizes very fast RISC with a rate constant (<i>k</i><sub>RISC</sub>) of 1.2×10<sup>7</sup> s<sup>−1</sup>. The large <i>k</i><sub>RISC</sub> of the emitter resulted in great device performance in the applications to blue TADF assisted fluorescence organic light-emitting diodes (OLEDs) as well as TADF-emitter OLEDs.<br>

Design of Thermally Activated Delayed Fluorescence Emitters for Organic Solid-State Microlasers

2021 ◽  
Author(s):  
Hongbing Fu ◽  
Shuai Li ◽  
Xue Jin ◽  
Zhenyi Yu ◽  
Xiaoxiao Xiao ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Solid State ◽  
Energy Gap ◽  
Delayed Fluorescence ◽  
Triplet States ◽  
Small Energy ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Organic Solid ◽  
Singlet And Triplet States

Small energy gap between charge transfer (CT) singlet and triplet states enables thermally activated delayed fluorescence (TADF). Nevertheless, the small oscillator strength associated with CT states and their long exciton...

scholarly journals Efficient Deep-Blue Electroluminescence Employing Heptazine-Based Thermally Activated Delayed Fluorescence

Photonics ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 293
Author(s):  
Jie Li ◽  
Jincheng Zhang ◽  
Heqi Gong ◽  
Li Tao ◽  
Yanqing Wang ◽  
...  
Keyword(s):  
High Performance ◽  
Light Emitting Diode ◽  
Blue Emission ◽  
Delayed Fluorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Thermally Activated ◽  
Deep Blue ◽  
Blue Emitters

We report an efficient deep-blue organic light-emitting diode (OLED) based on a heptazine-based thermally activated delayed fluorescent (TADF) emitter, 2,5,8-tris(diphenylamine)-tri-s-triazine (HAP-3DPA). The deep-blue-emitting compound, HAP-3DPA, was designed and synthesized by combining the relatively rigid electron-accepting heptazine core with three electron-donating diphenylamine units. Due to the rigid molecular structure and intramolecular charge transfer characteristics, HAP-3DPA in solid state presented a high photoluminescence quantum yield of 67.0% and obvious TADF nature with a short delayed fluorescent lifetime of 1.1 μs. Most importantly, an OLED incorporating HAP-3DPA exhibited deep-blue emission with Commission Internationale de l’Eclairage (CIE) coordinates of (0.16, 0.13), a peak luminance of 10,523 cd/m−2, and a rather high external quantum efficiency of 12.5% without any light out-coupling enhancement. This finding not only reports an efficient deep-blue TADF molecule, but also presents a feasible pathway to construct high-performance deep-blue emitters and devices based on the heptazine skeleton.

scholarly journals Molecular Design Realizing Very Fast Reverse Intersystem Crossing in Purely Organic Emitter

2019 ◽  
Author(s):  
yoshimasa wada ◽  
Hiromichi Nakagawa ◽  
Soma Matsumoto ◽  
Yasuaki Wakisaka ◽  
Hironori Kaji
Keyword(s):  
Energy Gap ◽  
Molecular Design ◽  
Delayed Fluorescence ◽  
Intersystem Crossing ◽  
Triplet States ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Donor And Acceptor ◽  
Spin Inversion

Reverse intersystem crossing (RISC), originally considered forbidden in purely organic materials, has been recently enabled by minimizing the energy gap between the lowest singlet excited state (S<sub>1</sub>) and lowest triplet state (T<sub>1</sub>) in thermally activated delayed fluorescence (TADF) systems. However, direct spin-inversion between S<sub>1</sub> and T<sub>1</sub> is still inefficient when both states are of the same charge transfer (CT) nature (i.e. <sup>1</sup>CT and <sup>3</sup>CT, respectively). Intervention of locally excited triplet states (<sup>3</sup>LE) between <sup>1</sup>CT and <sup>3</sup>CT is expected to trigger fast spin-flip. Here, we report on the systematic-design of the ideal TADF molecules with near-degenerate <sup>1</sup>CT, <sup>3</sup>CT and <sup>3</sup>LE states by controlling the through-space distance between the donor and acceptor segments in a molecule with tilted intersegment angles. The new system realizes very fast RISC with a rate constant (<i>k</i><sub>RISC</sub>) of 1.2×10<sup>7</sup> s<sup>−1</sup>. The large <i>k</i><sub>RISC</sub> of the emitter resulted in great device performance in the applications to blue TADF assisted fluorescence organic light-emitting diodes (OLEDs) as well as TADF-emitter OLEDs.<br>

A study on the effect of a pyridine secondary acceptor on the emission properties of thermally activated delayed fluorescence emitters

2020 ◽  
Vol 8 (22) ◽  
pp. 7485-7491
Author(s):  
Sung Joon Yoon ◽  
Ho Jung Lee ◽  
Kyung Hyung Lee ◽  
Jun Yeob Lee
Keyword(s):  
Molecular Design ◽  
Delayed Fluorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Emission Properties ◽  
Thermally Activated

A new molecular design of thermally activated delayed fluorescence (TADF) emitters having a pyridine derived secondary acceptor was developed.

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