Bipolar host materials for high-efficiency blue phosphorescent and delayed-fluorescence OLEDs

Li, Wei; Li, Jiuyan; Liu, Di; Wang, Fang; Zhang, Shufen

doi:10.1039/c5tc02997j

Cited by 68 publications

(50 citation statements)

References 32 publications

(31 reference statements)

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“…The structures of their reference compounds PyDCz and PySCz, and synthetic routes for all compounds are shown in Scheme S1 in the Supporting Information. These compounds were prepared at 71–80% yields by Suzuki cross‐coupling reaction between carbazole‐contained boronic acids and brominated n‐type units following the synthetic procedure in Scheme S1 (Supporting Information). The synthetic details and characterization of these compounds are provided in the Supporting Information.…”

Section: Resultsmentioning

confidence: 99%

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Molecular Engineering of Host Materials for High‐Performance Phosphorescent OLEDs: Zig‐Zag Conformation with 3D Gridding Packing Mode Facilitating Charge Balance and Quench Suppression

Wang

Liu

et al. 2018

Adv Funct Materials

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A group of bipyridine/carbazole hybrid compounds, namely m-BPyDCz, p-BPyDCz, m-BPySCz, and p-BPySCz, are designed and developed as host materials for phosphorescent organic light-emitting diodes (PhOLEDs). By tuning the p/n molar ratio and para-/meta-substitution style, scorpion-, Y-, Z-, and L-shape molecular conformations are generated. In virtue of intermolecular hydrogen bonds and π-π interaction, these compounds form different molecular packing patterns in their single crystals. Particularly the Z-shaped m-BPySCz achieves 3D gridding packing with regular and ordered carbazole and pyridine columns as carrier hoping channels and larger intermolecular distance, which not only guarantees charge balance but also suppresses exciton quenching. Consequently the m-BPySCz hosted sky-blue and green PhOLEDs exhibit high external quantum efficiencies of 27.3% and 28.0% and low efficiency roll-offs of 8.1% (at brightness of 1000 cd m −2 for blue) and 14.3% (at 10000 cd m −2 for green), all superior to other analogs and many reported host materials. The excellent performance of m-BPySCz versus its lowest molecular weight and lowest amorphous stability manifests that the molecular packing style of host material dominates to determine the overall performance of PhOLEDs and the 3D gridding packing mode of zig-zag conformation may be one ideal strategy to eliminate efficiency roll-off in PhOLEDs.

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Section: Resultsmentioning

confidence: 99%

“…Their hole and electron mobilities were measured by the space charge limited current technique . The ohmic contact single‐carrier devices were designed and fabricated with the structure of ITO/MoO 3 (7 nm)/host (100 nm)/Al (200 nm) for hole‐only devices and ITO/host (100 nm)/LiF (1 nm)/Al (200 nm) for electron‐only devices, respectively.…”

Section: Resultsmentioning

confidence: 99%

Molecular Engineering of Host Materials for High‐Performance Phosphorescent OLEDs: Zig‐Zag Conformation with 3D Gridding Packing Mode Facilitating Charge Balance and Quench Suppression

Wang

Liu

et al. 2018

Adv Funct Materials

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“…Blue delayed fluorescent emitters harvest singlet emission by a reverse intersystem crossing process (TADF) or triplet‐triplet fusion (TTF) process . In conventional fluorescent emitters, triplet excitons are lost by non‐radiative transition, but can be converted into singlet excitons by small singlet‐triplet energy gap driven up‐conversion (TADF) or triplet‐triplet collision induced reverse intersystem crossing.…”

Section: Basic Emission Mechanism Of Blue Fluorescence Phosphorescenmentioning

confidence: 99%

Recent Progress in High‐Efficiency Blue‐Light‐Emitting Materials for Organic Light‐Emitting Diodes

Byun

Kim

et al. 2017

Adv Funct Materials

502

263

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Organic light-emitting diodes (OLEDs) are increasingly used in displays replacing traditional flat panel displays; e.g., liquid crystal displays. Especially, the paradigm shifts in displays from rigid to flexible types accelerated the market change from liquid crystal displays to OLEDs. However, some critical issues must be resolved for expansion of OLED use, of which blue device performance is one of the most important. Therefore, recent OLED material development has focused on the design, synthesis and application of highefficiency and long-life blue emitters. Well-known blue fluorescent emitters have been modified to improve their efficiency and lifetime, and blue phosphorescent emitters are being investigated to overcome the lifetime issue. Recently, thermally activated delayed fluorescent emitters have received attention due to the potential of high-efficiency and long-living emitters. Therefore, it is timely to review the recent progress and future prospects of high-efficiency blue emitters. In this feature article, we summarize recent developments in blue fluorescent, phosphorescent and thermally activated delayed fluorescent emitters, and suggest key issues for each emitter and future development strategies.

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“…The fluorescence spectrum at 77 K exhibits the well-defined vibronic peaks, which is reported in other host materials. 17 Therefore, E T was estimated from the highestenergy of the phosphorescence spectrum as 3.01 eV. All spectra data are summary in Table 1.…”

Section: Introductionmentioning

confidence: 99%

1,2,4-Triazole derivatives as host materials for blue and green phosphorescent organic light-emitting devices

Sun

Wang

et al. 2016

Tetrahedron

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Bipolar host materials for high-efficiency blue phosphorescent and delayed-fluorescence OLEDs

Cited by 68 publications

References 32 publications

Molecular Engineering of Host Materials for High‐Performance Phosphorescent OLEDs: Zig‐Zag Conformation with 3D Gridding Packing Mode Facilitating Charge Balance and Quench Suppression

Molecular Engineering of Host Materials for High‐Performance Phosphorescent OLEDs: Zig‐Zag Conformation with 3D Gridding Packing Mode Facilitating Charge Balance and Quench Suppression

Recent Progress in High‐Efficiency Blue‐Light‐Emitting Materials for Organic Light‐Emitting Diodes

1,2,4-Triazole derivatives as host materials for blue and green phosphorescent organic light-emitting devices

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