Ambipolar D–A type bifunctional materials with hybridized local and charge-transfer excited state for high performance electroluminescence with EQE of 7.20% and CIEy ∼ 0.06

Liu, Bin; Yu, Ziwei; He, Dan; Zhu, Ze‐Lin; Zheng, Ji; Yu, Yadong; Xie, Wenfa; Tong, Qing‐Xiao; Lee, Chun‐Sing

doi:10.1039/c7tc01133d

Cited by 114 publications

(69 citation statements)

References 66 publications

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“…Besides, compound 1 and 2 were synthesized as reported. [24][25][26] One-step Suzuki cross-coupling reaction was used to synthesize the target products ICz-PPI and 2ICz-PPI. The crude product was purified by silica column chroma-tography and characterized with 1 H NMR spectroscopy, mass spectrometry and elemental analysis (see the Supporting Information).…”

Section: Synthesis Methodsmentioning

confidence: 99%

Versatile Host Materials for Highly‐Efficient Green, Red Phosphorescent and White Organic Light‐Emitting Diodes

et al. 2019

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To build up efficient host materials, two novel organic small molecules ICz‐PPI and 2ICz‐PPI were designed and synthesized, in which phenanthro[9,10‐d]imidazole (PI) is proposed as a potential luminophore with high stability, while the indolo[3,2,1‐jk]carbazole (ICz) has a high triplet energy and excellent thermal stability. Both exhibited weak intramolecular charge transfer, high decomposition temperature (Td) and high quantum yield. ICz‐PPI and 2ICz‐PPI can act as the emitting layer in non‐doped organic light‐emitting diodes (OLEDs), which achieved an external quantum efficiency (EQE) of 2.47 and 1.94 % with CIE coordinates of (0.153, 0.121) and (0.161, 0.102), respectively. In addition, the high triplet energy allows them to be used as hosts for phosphorescent OLEDs (PhOLEDs). Accordingly, high performance for green (62.5 cd A−1, 70.9 lm W−1, 17.8 %) and red (25.7 cd A−1, 26.9 lm W−1, 19.4 %) had been achieved from the ICz‐PPI‐based PhOLED. Particularly, the ICz‐PPI‐based red PhOLED showed surprisingly low roll‐off and maintained an EQE of 14.9 % at 10 000 cd m−2. Furthermore, an ICz‐PPI‐based white OLED (WOLED) exhibited warm white light (CIEx,y=(0.427, 0.468)) and high efficiencies with a CEmax of 31.8cd A−1, PEmax of 37.0lm W−1 and EQEmax of 14.4 %.

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Section: Synthesis Methodsmentioning

confidence: 99%

Versatile Host Materials for Highly‐Efficient Green, Red Phosphorescent and White Organic Light‐Emitting Diodes

et al. 2019

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“…To understand why tenfold increase in maximum brightness was observed for the device, based on compound 3f containing methoxy group in comparison to that of device based on non‐substituted emitter 3a (Figure c), we plotted brightness vs. current density for the fabricated devices (Figure S10). These dependences were well linearly fitted with the slope of 1 for all the devices at low brightness demonstrating that their electroluminescence resulted from singlet exciton recombination . In case of device f , the liner dependence of brightness vs. current density was observed at high current density (Figure R1).…”

Section: Synthesis and Characterizationmentioning

confidence: 66%

Rational Synthesis of Tetrahydrodibenzophenanthridine and Phenanthroimidazole as Efficient Blue Emitters and their Applications

et al. 2020

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Ten luminophores based on tetrahydrodibenzophenanthridine (THDP) and phenanthroimidazole (PI) were designed, synthesized and characterized for their thermal, electrochemical, electro‐optical, charge‐transporting characteristics and electroluminescent properties. The blue luminophores exhibited high photoluminescence quantum yields of 66–93 % in toluene solutions and of 5–59 % in solid films. The highest values were observed for the derivative of THDP and PI containing methoxy group. The compounds showed close values of ionization potentials (5.74–6.11 eV) and electron affinities (2.71–3.06 eV). The selected compounds were tested in electroluminescent devices for the preparation of non‐doped light‐emitting layers. The best device fabricated using derivative of THDP and PI with methoxy groups showed blue electroluminescence with brightness of 10000 cd/m2 at high applied voltages. We performed DFT calculations and observed lowest singlet–triplet gap (ΔEST) values of 0.33 and 0.03 eV, oscillator strength (f) values of 0.034 and 0.008 for CN and NO2 derivatives. Interestingly, we also observed that compounds 3g and 3i showed HOMO and LUMO levels with similar energy gap (Eg) of 3.60 eV and deeper HOMO values of –5.30, –5.33 eV and LUMO values of –1.94, –2.77 eV.

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“…The starting materials were obtained from suppliers and used without further purification. PPIBBr was synthesized as reported . The Suzuki cross‐coupling reaction was used to synthesize the target product PPI‐2BI .…”

Section: Resultsmentioning

confidence: 99%

“…[29] Actually,B Ii sc ommonly used as electron acceptor in D-A molecules owing to the fused benzene ring in BI that tends to decrease the proton affinity of the pyridine-liken itrogen by changing its electron density, [30][31] whereas,t he natural bipolar property of the PI group can both donate and receive electrons in push-pull systems. [22,25,32] These suggest that the PI group has stronger electron-donating properties than the BI group. Frontier molecular orbital analysis was used to further calculate the electronic properties of PPI-2BI at the B3LYP/6-31G(d,p) level.…”

Section: Theoretical Calculationsmentioning

confidence: 95%

“…Scheme 1s hows the synthetic routes to PPI-2BI.T he starting materials were obtainedf rom suppliers and used withoutf urther purification.P PIBBr was synthesized as reported. [22] The Suzuki cross-coupling reaction was used to synthesize the target product PPI-2BI.T he crude compound was purified by silica column chromatography andc haracterizedw ith NMR spectroscopy,m ass spectrometry,a nd elementala nalysis (see the Supporting Information).…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

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Ternary Acceptor–Donor–Acceptor Asymmetrical Phenanthroimidazole Molecule for Highly Efficient Near‐Ultraviolet Electroluminescence with External Quantum Efficiency (EQE) >4 %

Liu

Zhu

Zhao

et al. 2018

Chemistry A European J

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A new ternary acceptor (A)-donor (D)-acceptor (A) asymmetrically twisted deep-blue emitting molecule, PPI-2BI, was synthesized by attaching two electrophilic benzimidazole (BI) units to the C2 and N1 positions of a phenanthroimidazole (PI) donor unit. Profiting from the enhanced D-A electronic coupling, the electron injecting and transporting abilities of the new triangle-shaped A-D-A molecule are considerably improved and the molecule shows high photoluminescence (PL) and electroluminescence (EL) efficiencies. By using PPI-2BI as a non-doped emitting layer (EML), the resulting organic light-emitting device exhibits emission with color coordinates of (0.158, 0.124) and a maximum external quantum efficiency (EQE), current efficiency (CE), and power efficiency (PE) of 4.63 %, 4.98 cd A , and 4.82 lm W , respectively. Additionally, a simple bilayer device using PPI-2BI as both the EML and the electron-transporting layer (ETL) also shows an EQE of 3.81 % with little changes to the color purity. Remarkably, a PPI-2BI-based doped device emits efficient near-ultraviolet EL with color coordinates of (0.154, 0.047) and an EQE of 4.12 %, which is comparable to that of the best reported near-UV emitting devices.

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Ambipolar D–A type bifunctional materials with hybridized local and charge-transfer excited state for high performance electroluminescence with EQE of 7.20% and CIEy ∼ 0.06

Abstract: Achieving high-performance electroluminescence with EQE of 7.20% and CIEy ∼ 0.06 based on bipolar materials with intercrossed excited state characteristics.

Cited by 114 publications

References 66 publications

Versatile Host Materials for Highly‐Efficient Green, Red Phosphorescent and White Organic Light‐Emitting Diodes

Versatile Host Materials for Highly‐Efficient Green, Red Phosphorescent and White Organic Light‐Emitting Diodes

Rational Synthesis of Tetrahydrodibenzophenanthridine and Phenanthroimidazole as Efficient Blue Emitters and their Applications

Ternary Acceptor–Donor–Acceptor Asymmetrical Phenanthroimidazole Molecule for Highly Efficient Near‐Ultraviolet Electroluminescence with External Quantum Efficiency (EQE) >4 %

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