Thermally activated delayed fluorescence blue dopants and hosts: from the design strategy to organic light-emitting diode applications

Godumala, Mallesham; Choi, Suna; Cho, Min Ju; Choi, Dong Hoon

doi:10.1039/c6tc04377a

Cited by 168 publications

(103 citation statements)

References 62 publications

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“…Since then, a lot of TADF molecules with spiro centers have been reported with different EWGs such as anthracenone, diazafluorene, terpyridine‐substituted spirofluorene, etc. These materials can even act as hosts for phosphorescent emitters, and form exciplexes with other materials to realize white OLEDs . The rigidity and thermal stability make them suitable candidates for TADF‐OLEDs.…”

Section: Basic Design Strategies Of Three Tadf Molecular Systemsmentioning

confidence: 99%

“…The TADF materials can even be employed as sensitizers to provide an alternative exciton utilization solution and boost the efficiency of secondary dopants . TADF materials can also be introduced as hosts for fluorescent, phosphorescent, and even TADF emitters, providing an efficient and diverse pathway of achieving highly‐efficient OLEDs, and in some cases, much more simplified white organic light emitting diodes (WOLEDs) fabrication …”

Section: Introductionmentioning

confidence: 99%

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Thermally Activated Delayed Fluorescence Materials: Towards Realization of High Efficiency through Strategic Small Molecular Design

Liang

Zheng

2019

Chemistry A European J

173

123

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Thermally activated delayed fluorescence (TADF) is one of the most intriguing and promising discoveries towards realization of highly‐efficient organic light emitting diodes (OLED) utilizing small molecules as emitters. It has the capability of manifesting all excitons generated during the electroluminescent processes, consequently achieving 100 % of internal quantum efficiency. Since the report of the first efficient OLED based on a TADF small molecule in 2012 by Adachi et al., the quest for optimal TADF materials for OLED application has never stopped. Various TADF molecules bearing different design concepts and strategies have been designed and produced, with the aim to boost the overall performances of corresponding OLEDs. In this minireview, the general principles of TADF molecular design based on three basic categories of TADF species: twisted intramolecular charge transfer (TICT), through‐space charge transfer (TSCT) and multi‐resonance induced TADF (MR‐TADF) are discussed in detail. Several key aspects with respect to each category, as well as some effective methods to enhance the efficiency of TADF materials and corresponding OLEDs from the molecular engineering perspectives, are summarized and discussed to exhibit a general landscape of TADF molecular design to a wide variety of scientific researchers within this particular disciplinary area.

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Section: Basic Design Strategies Of Three Tadf Molecular Systemsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermally Activated Delayed Fluorescence Materials: Towards Realization of High Efficiency through Strategic Small Molecular Design

Liang

Zheng

2019

Chemistry A European J

173

123

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“…The most important requirement for potential TADF materials is a small energy gap (Δ E ST ) between their lowest singlet (S 1 ) and triplet (T 1 ) excited states . Generally, small Δ E ST can be achieved through design of donor–acceptor (D‐A) systems with twisted geometry to attain spatial separation between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), and also to minimize the exchange integrals between these orbitals . Accordingly, D‐A molecular systems with a marked intramolecular charge transfer (ICT) are typical TADF material candidates .…”

Section: Introductionmentioning

confidence: 99%

“…The cyano group is a strongly electron‐withdrawing moiety and is useful for the design of highly polar D‐A type TADF materials with a reduced singlet‐triplet energy gap . Using cyano group linked to suitable electron‐donating system is a universal and convenient strategy to develop high‐performance TADF emitters …”

Section: Introductionmentioning

confidence: 99%

Aggregation‐Enhanced Emission and Thermally Activated Delayed Fluorescence of Derivatives of 9‐Phenyl‐9H‐Carbazole: Effects of Methoxy and tert‐Butyl Substituents

Grybauskaite-Kaminskiene

Volyniuk

Mimaitė

et al. 2018

Chemistry A European J

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Derivatives of 9-phenyl-9H-carbazole were synthesized as efficient emitters exhibiting both thermally activated delayed fluorescence and aggregation-induced emission enhancement. Effects of methoxy and tert-butyl substituents at the different positions of carbazolyl groups on the properties of the emitters were studied. Depending on the substitutions, photoluminescence quantum yields (PLQY) of non-doped solid films of the compounds ranged from 17 % to 53 % which were much higher than those observed for the solutions in low-polarity solvent toluene. Compounds substituted at C-3 and C-6 positions of carbazole moiety by methoxy- and tert-butyl- groups showed the highest solid-state PLQY. Ionization potentials of the studied derivatives in solid-state were found to be in the short range of 5.75-5.89 eV. Well-balanced hole and electron mobilities were detected for tert-butyl-substituted compound. They exceeded 10 cm (V×s) at electric fields higher than 3×10 V cm . Two compounds with the highest solid-state PLQYs showed higher efficiencies in non-doped organic light-emitting diodes than in the doped devices. Maximum external quantum efficiency of 7.2 % and brightness of 15000 cd m were observed for the best device.

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“…[11][12][13] Recently, thermally activated delayed fluorescence (TADF) emitters based on pure organic compounds have been considered as an alternate technology to phosphorescent counterparts to realize an IQE of 100%. [14][15][16][17][18][19][20][21][22][23][24][25] Until recently, several TADF OLEDs have achieved a high EQE of over 30% at maximum. [26][27][28][29][30][31][32] The efficiency of the TADF-based OLEDs is expected to exceed that of OLEDs based on phosphorescent emitters due to the unlimited molecular design of pyrimidine derivative-based TADF emitters.…”

Section: Introductionmentioning

confidence: 99%

Recent progress of pyrimidine derivatives for high-performance organic light-emitting devices

2018

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Abstract. Pyrimidine is an electron-deficient azaaromatic compound containing two nitrogen atoms at 1, 3-positions that plays a key role as an organic semiconductor or semiconducting material. Because of the high electron-accepting property induced by C═N double bonds and due to its coordination ability, pyrimidine has been incorporated as a building block in phosphorescent emitters, fluorescent emitters, bipolar host materials, and electron transporting materials in organic light-emitting devices (OLEDs). Recently, pyrimidine-based thermally activated delayed fluorescent emitters combined with various electron donors have been developed, and their device performances were far better than those based on conventional fluorescent emitters. In this review, recent progress of pyrimidine-based OLED materials is presented and accompanied by a historical overview, current status, key issues, and outlook for the next generation of high-performance OLED materials.

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Thermally activated delayed fluorescence blue dopants and hosts: from the design strategy to organic light-emitting diode applications

Abstract: Thermally activated delayed fluorescence materials exhibited outstanding external quantum efficiencies in OLEDs along with good CIE color coordinates and improved device stabilities. Hence these are most promising for commercialization of OLEDs.

Cited by 168 publications

References 62 publications

Thermally Activated Delayed Fluorescence Materials: Towards Realization of High Efficiency through Strategic Small Molecular Design

Thermally Activated Delayed Fluorescence Materials: Towards Realization of High Efficiency through Strategic Small Molecular Design

Aggregation‐Enhanced Emission and Thermally Activated Delayed Fluorescence of Derivatives of 9‐Phenyl‐9H‐Carbazole: Effects of Methoxy and tert‐Butyl Substituents

Recent progress of pyrimidine derivatives for high-performance organic light-emitting devices

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