Electroplex as a New Concept of Universal Host for Improved Efficiency and Lifetime in Red, Yellow, Green, and Blue Phosphorescent Organic Light‐Emitting Diodes

Song, Wook; Lee, Jun Yeob; Cho, Yongjoo; Yu, Hyeonghwa; Aziz, Hany; Lee, Kang Mun

doi:10.1002/advs.201700608

Cited by 53 publications

(16 citation statements)

References 36 publications

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“…According to the previous results reported in literatures [22,28,40], the newly formed peaks in EL spectra were possibly related to phosphorous emission, exciplex emission, or/and electroplex emission. As the shoulder peak could not be observed in the PL spectrum of the solid film, it should not be caused by phosphorous emission [40].…”

Section: Energy Levels and Theoreticsupporting

confidence: 69%

“…This procedure produces the CT configuration, accompanied with the electroplex emission [42]. In Song et al's case [28], the LUMO gap between 3,3-di(9H-carbazol-9-yl)biphenyl (mCBP) and 2,8-bis(4,6-diphenyl-1,3,5-triazin-2-yl)dibenzo[b,d]furan (DBFTrz) was around 0.5 eV. However, here, for 3Ph-Cz-CN and TPBi, the electron at the LUMO of TPBi could directly cross recombine with the holes at the HOMO of 3Ph-Cz-CN even though the LUMO gap was just 0.3 eV.…”

Section: Energy Levels and Theoreticmentioning

confidence: 98%

“…But different from exciplex, the newly formed peaks in EL spectra caused by the electroplex emission could not be observed in the PL spectra of the blend films of donor and acceptor molecules. Generally, the newly formed redshifted broad bands were employed to realize white emission [27,28], and there were no efforts of using electroplex or exciplex to enhance the device performance while controlling the red-shifted bands. In recent years, our group has focused on the research of blue OLEDs with the emphasis on the design of blue and deep-blue AIEgens (Chart S1) [29][30][31]; accordingly, we wondered that if we choose a deep-blue emitter with the properly controllable red-shifted bands, the overall blue emission OLED with high performance should be possible by utilizing the formation of electroplex or exciplex (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

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Utilizing Electroplex Emission to Achieve External Quantum Efficiency up to 18.1% in Nondoped Blue OLED

Zhan

Gong

et al. 2020

Research

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For the first time, electroplex emission is utilized to enhance the performance of nondoped blue organic light-emitting diodes (OLEDs). By decorating the twisted blue-emitting platform and adjusting the electronic structure, three molecules of 3Cz-Ph-CN, 3Cz-mPh-CN, and 3Ph-Cz-CN with a donor-acceptor structure are synthesized and investigated. When external voltage is applied, electroplex emission, which contributes to the emission performance of OLED, can be realized at the interface between the emitting layer and the electron-transporting layer. Accordingly, high external quantum efficiency of 18.1% can be achieved, while the emission wavelength of the device can be controlled in the blue region. Our results provide the possibility to enhance the performance of OLED through electroplex emission, in addition to the generally investigated thermally activated delayed fluorescence (TADF). Excitedly, when 3Ph-Cz-CN is used as host material in orange-emitting phosphorous OLEDs (PO-01 as the dopant), unprecedented high external quantum efficiency of 27.4% can also be achieved.

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Section: Energy Levels and Theoreticsupporting

confidence: 69%

Section: Energy Levels and Theoreticmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Utilizing Electroplex Emission to Achieve External Quantum Efficiency up to 18.1% in Nondoped Blue OLED

Zhan

Gong

et al. 2020

Research

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“…This will minimize the degradation of the devices by avoiding the decomposition of host materials in the emitting layer, extending the lifetime of the OLEDs. Moreover, the upconversion process occurring in the TADF‐type exciplex host will reduce the excited state lifetime of triplet excitons in the host compared to that occurring in a non‐TADF type host; this is helpful to improve the lifetime of the devices …”

Section: Lifetime Improvement Of Oleds By Tadf Hostsmentioning

confidence: 99%

Recent Progress of the Lifetime of Organic Light‐Emitting Diodes Based on Thermally Activated Delayed Fluorescent Material

et al. 2019

Self Cite

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that satisfy the physical parameters of the OLEDs, and this could be assisted by the use of organic materials. Therefore, organic materials have played a key role in extending the lifetime of OLEDs. In particular, host materials and emitters in the emitting layer have been the major contributors to the improved lifetime of OLEDs, although charge transport materials such as hole and electron transport materials, exciton blocking materials, and carrier injection layers have also supported their extended lifetime. The advance in the lifetime of PhOLEDs has been dominantly assisted by the host materials, while that of TADF OLEDs has been mostly assisted by the emitters. Particularly, among several different types of host materials, the TADF-type hosts were the most effective hosts for long lifetime in the PhOLEDs. Therefore, TADF materials have played a decisive role in the development of highly efficient and long lifetime OLEDs.This progress report discusses the contribution of TADF materials toward the lifetime improvement of PhOLEDs as hosts and TADF OLEDs as emitters. The material design and device performances of the TADF materials are mainly examined based on recent studies that include the long lifetime PhOLEDs and TADF OLEDs assisted by TADF materials. The material designs of the intermolecular-type TADF hosts, the intramolecular-type TADF hosts, and the intramolecular-type TADF emitters for both high efficiency and long lifetime are widely covered in this report. Moreover, future possibilities of the TADF materials as hosts and emitters for long lifetime OLEDs are also proposed. The application of the TADF materials is summarized in Figure 1. Recently, the external quantum efficiency and lifetime of organic light-emitting diodes (OLEDs) have been dramatically upgraded due to development of organic materials and device structure. In particular, an intramolecular or intermolecular complex based on thermally activated delayed fluorescent (TADF) materials has greatly contributed to improving OLED device performance. Although high external quantum efficiency has been the main objective of the development of TADF materials as hosts and emitters, recent interest has been directed towards the lifetime of TADFmaterial-based OLEDs. For the past several years, remarkable advances in the lifetime of phosphorescent and TADF OLEDs have been made using TADF materials as hosts or emitters in the emitting layer. Therefore, since TADF materials are useful as both hosts and emitters for a long lifetime, this work discusses the recent progress made in developing TADF materials for long-lifetime OLEDs.

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“…Previous studies have found that device lifetime can be enhanced by maximizing the RZ width . In conventional mixed‐ and graded‐EML devices, electron‐ and hole‐transporting hosts are mixed to achieve high charge balance and a wide RZ . The absolute position of the RZ is also important, as proximity to a transport layer interface can exacerbate degradation, or influence exciton confinement and charge balance .…”

Section: Introductionmentioning

confidence: 99%

Improved stability in organic light‐emitting devices by mixing ambipolar and wide energy gap hosts

et al. 2019

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Electroplex as a New Concept of Universal Host for Improved Efficiency and Lifetime in Red, Yellow, Green, and Blue Phosphorescent Organic Light‐Emitting Diodes

Cited by 53 publications

References 36 publications

Utilizing Electroplex Emission to Achieve External Quantum Efficiency up to 18.1% in Nondoped Blue OLED

Utilizing Electroplex Emission to Achieve External Quantum Efficiency up to 18.1% in Nondoped Blue OLED

Recent Progress of the Lifetime of Organic Light‐Emitting Diodes Based on Thermally Activated Delayed Fluorescent Material

Improved stability in organic light‐emitting devices by mixing ambipolar and wide energy gap hosts

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