Recent development of organic light-emitting diode utilizing energy transfer from exciplex to phosphorescent emitter

Seo, Satoshi; Shitagaki, Satoko; Ohsawa, Nobuharu; Inoue, Hideko; Suzuki, Kazuyuki; Nowatari, Hiromi; Takahashi, Tatsuyoshi; Hamada, Takao; Watabe, Takeyoshi; Yamada, Yui; Mitsumori, Satomi

doi:10.1117/12.2236191

Cited by 4 publications

(1 citation statement)

References 40 publications

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“…There are only a few HTLs that fulfill all the requirements of: 1) commercially available, 2) wide energy‐gap, 3) long‐term stability, and 4) used in OLEDs in the scientific literatures. Among them, N 4, N 4′‐bis(dibenzo[b,d]thiophen‐4‐yl)‐ N 4, N 4′‐diphenylbiphenyl‐4,4′‐diamine ( DBTPB ), which is developed by Fukagawa and co‐workers,, is a commercially available, and has already realized promising operational stability of green phosphorescent OLEDs with high η ext at high brightness of 1000 cd m −2 . Additionally, DBTPB has DBT units, and enables simple comparison.…”

Section: Resultsmentioning

confidence: 99%

A Novel Sterically Bulky Hole Transporter to Remarkably Improve the Lifetime of Thermally Activated Delayed Fluorescent OLEDs at High Brightness

Kamata

Sasabe

Igarashi

et al. 2017

Chemistry A European J

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For the practical application of organic light emitting devices (OLEDs) based on thermally activated delayed fluorescence (TADF) for large area TV and solid state lighting, low power consumption as well as the operation lifetime at high brightness over 1000 cd m must be improved. Here, we have developed a novel hexaphenylbenzene-based sterically bulky hole-transport layer named 4DBTHPB with deep ionization potential of 5.8 eV and high triplet energy of 2.7 eV. By using 4DBTHPB, we can realize a highly efficient and stable TADF OLED exhibiting external quantum efficiency of 21.6 % and power efficiency of 54.3 lm W and operation lifetime at 50 % (LT ) of approximately 10 000 h at an initial luminance of 1000 cd m . These performances are comparable to those of the state-of-the-art green phosphorescent OLEDs reported in the scientific literatures.

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Section: Resultsmentioning

confidence: 99%

A Novel Sterically Bulky Hole Transporter to Remarkably Improve the Lifetime of Thermally Activated Delayed Fluorescent OLEDs at High Brightness

Kamata

Sasabe

Igarashi

et al. 2017

Chemistry A European J

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Origin and Control of Orientation of Phosphorescent and TADF Dyes for High‐Efficiency OLEDs

2018

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It has been known for decades that the emitting dipole orientation (EDO) of emitting dyes influences the outcoupling efficiency of organic light-emitting diodes (OLEDs). However, the EDO of dopants, especially phosphorescent dopants, has been studied less than that of neat films and polymer emitting layers (EMLs) due to the lack of an apparent driving force for aligning the dopants in amorphous host films. Recently, however, even globular-shaped Ir complexes have been reported to have a preferred orientation in doped films and OLEDs. External quantum efficiencies (EQEs) higher than 30% have also been demonstrated using phosphorescent and thermally activated delayed fluorescent dyes (TADF) doped in EMLs. Here, recent results on the EDO of phosphorescent and TADF dyes doped in host films, and highly efficient OLEDs using these dyes are reviewed. The origin and control of the orientation of phosphors are discussed, followed by a discussion of future strategies to achieve EQEs of over 60% without a light extraction layer, from the material point of view.

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A Series of Dibenzofuran‐Based n‐Type Exciplex Host Partners Realizing High‐Efficiency and Stable Deep‐Red Phosphorescent OLEDs

Igarashi

Sasabe

Nagai

et al. 2019

Chemistry A European J

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Deep‐red to near‐infrared (NIR) OLEDs, which yield emission peak wavelengths beyond λ=660 nm, are applicable as unique light sources in plant growth or health monitoring systems. Compared with other visible‐spectrum OLEDs, however, research in the field of deep‐red OLEDs is not as advanced. In this work, three new types of dibenzofuran‐based host materials are developed as n‐type exciplex host partners. Combining these with the deep‐red iridium complex bis(2,3‐diphenylquinoxaline)iridium(dipivaloylmethane) ([(DPQ)2Ir(dpm)]) and N,N′‐di(naphalene‐1‐yl)‐N,N′‐diphenylbenzidine (α‐NPD) as a p‐type exciplex host partner, a highly efficient deep‐red OLED can be realized with a maximum external quantum efficiency (ηext,max) of over 16 % with Comission Internationale de l′Éclairge (CIE) coordinates of (0.71, 0.28). In addition, the effect of the doping concentration and the p/n ratio of the exciplex host on the efficiency and the lifetime of the OLEDs are investigated. Consequently, the optimized device exhibits a ηext,max of over 15 % and a six‐time longer lifetime operating at high brightness of 100 cd m−2 compared with other state‐of‐the‐art deep‐red OLEDs.

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Recent development of organic light-emitting diode utilizing energy transfer from exciplex to phosphorescent emitter

Cited by 4 publications

References 40 publications

A Novel Sterically Bulky Hole Transporter to Remarkably Improve the Lifetime of Thermally Activated Delayed Fluorescent OLEDs at High Brightness

A Novel Sterically Bulky Hole Transporter to Remarkably Improve the Lifetime of Thermally Activated Delayed Fluorescent OLEDs at High Brightness

Origin and Control of Orientation of Phosphorescent and TADF Dyes for High‐Efficiency OLEDs

A Series of Dibenzofuran‐Based n‐Type Exciplex Host Partners Realizing High‐Efficiency and Stable Deep‐Red Phosphorescent OLEDs

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