scholarly journals “Rate-limited effect” of reverse intersystem crossing process: the key for tuning thermally activated delayed fluorescence lifetime and efficiency roll-off of organic light emitting diodes

2016 ◽  
Vol 7 (7) ◽  
pp. 4264-4275 ◽  
Author(s):  
Xinyi Cai ◽  
Xianglong Li ◽  
Gaozhan Xie ◽  
Zuozheng He ◽  
Kuo Gao ◽  
...  
Keyword(s):  
Rate Constant ◽  
Fluorescence Lifetime ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Intersystem Crossing ◽  
Limited Effect ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light

The rate constant of reverse intersystem crossing was found to be the “rate-limited step” in thermally activated delayed fluorescence lifetime governing.

scholarly journals Thioxanthone-based thermally activated delayed fluorescence emitters showing fast reverse intersystem crossing for efficient organic light-emitting diodes with small efficiency roll-off

2021 ◽  
Author(s):  
Yongxia Ren ◽  
Yoshimasa Wada ◽  
Katsuaki Suzuki ◽  
Yu Kusakabe ◽  
Jan Geldsetzer ◽  
...  
Keyword(s):  
Rate Constant ◽  
Light Emitting Diodes ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Intersystem Crossing ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light ◽  
Large Rate Constant

Abstract Thermally activated delayed fluorescence-based organic light-emitting diodes (TADF OLEDs) usually suffer from severe efficiency roll-off at high brightness which is considered to originate from slow reverse intersystem crossing (RISC) and resulting long-lived triplet excitons. The development of TADF molecules with very fast RISC is an effective approach to overcome this issue. Here, we report two TADF molecules (MCz-TXO, DMCz-TXO) having thioxanthone as an acceptor unit to introduce heavy atom effect. Theoretical calculations predict that both molecules will achieve close energy level matching of the charge-transfer and locally excited triplet states (3CT and 3LE, respectively), together with a small energy gap between 3CT and the lowest excited singlet state. The newly designed molecule, MCz-TXO, showed an extremely large rate constant of RISC (kRISC) of 6.4×107 s− 1, one of the largest kRISC values among all reported pure organic TADF emitters. Moreover, DMCz-TXO showed not only a large kRISC but also a large rate constant of radiative decay both exceeding 107 s− 1, offering a sub-microsecond-scale delayed lifetime (~ 0.8 µs). These thioxanthone-based emitters exhibited great device performances with suppressed efficiency roll-offs at high luminance when applied to OLEDs.

Over 20% external quantum efficiency in red thermally activated delayed fluorescence organic light-emitting diodes using a reverse intersystem crossing activating host

2018 ◽  
Vol 6 (20) ◽  
pp. 5363-5368 ◽  
Author(s):  
Ji Han Kim ◽  
Dong Ryun Lee ◽  
Si Hyun Han ◽  
Jun Yeob Lee
Keyword(s):  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Intersystem Crossing ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light

Highly efficient red thermally activated delayed fluorescence organic light-emitting diodes were developed using a reverse intersystem crossing activating host derived from phenylcarbazole and pyridofuropyridine.

Electrostatic potential dispersing pyrimidine-5-carbonitrile acceptor for high efficiency and long lifetime thermally activated delayed fluorescence organic light-emitting diodes

2019 ◽  
Vol 7 (40) ◽  
pp. 12695-12703 ◽  
Author(s):  
Ji Seon Jang ◽  
Ha Lim Lee ◽  
Kyung Hyung Lee ◽  
Jun Yeob Lee
Keyword(s):  
Electrostatic Potential ◽  
High Efficiency ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light ◽  
Long Lifetime ◽  
Acceptor Moiety

Pyrimidine-5-carbonitrile was developed as an electrostatic potential managing and strong acceptor moiety of thermally activated delayed fluorescent (TADF) emitters for high efficiency and long lifetime in devices.

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...

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