Host and Dopant Materials for Idealized Deep‐Red Organic Electrophosphorescence Devices

Fan, Chun-Hsiang; Sun, Peipei; Su, Tsu‐Hui; Cheng, Chien‐Hong

doi:10.1002/adma.201100610

Cited by 195 publications

(108 citation statements)

References 33 publications

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“…Using Ir(III) complexes as emitters, blue, green, and orange OLEDs with external quantum efficiencies (EQEs) over 30% have been reported 8, 9, 10, 11, 12. However, even based on elaborately designed bipolar host materials and sophisticated device structures, only several most efficient vacuum‐deposited red OLEDs using Ir(III) complexes as emitters show EQEs around 26% 11, 13, 14, 15, 16. As for the solution‐processed red OLEDs based on Ir(III) complexes, the highest EQEs are less than 22% 17, 18, 19.…”

Section: Introductionmentioning

confidence: 99%

Diarylboron‐Based Asymmetric Red‐Emitting Ir(III) Complex for Solution‐Processed Phosphorescent Organic Light‐Emitting Diode with External Quantum Efficiency above 28%

et al. 2018

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Organic light‐emitting diodes (OLEDs) are one of the most promising technologies for future displays and lighting. Compared with the blue and green OLEDs that have achieved very high efficiencies by using phosphorescent Ir(III) complexes, the red OLEDs still show relatively low efficiencies because of the lack of high‐performance red‐emitting Ir(III) complexes. Here, three highly efficient asymmetric red‐emitting Ir(III) complexes with two different cyclometalating ligands made by incorporating only one electron‐deficient triarylboron group into the nitrogen heterocyclic ring are reported. These complexes show enhanced photoluminescence quantum yields up to 0.96 and improved electron transporting capacity. In addition, the asymmetric structure can help to improve the solubility of Ir(III) complexes, which is crucial for fabricating OLEDs using the solution method. The photoluminescent and oxidation–reduction properties of these Ir(III) complexes are investigated both experimentally and theoretically. Most importantly, a solution‐processed red OLED achieves extremely high external quantum efficiency, current efficiency, and power efficiency with values of 28.5%, 54.4 cd A−1, and 50.1 lm W−1, respectively, with very low efficiency roll‐off. Additionally, the related device has a significantly extended operating lifetime compared with the reference device. These results demonstrate that the asymmetric diarylboron‐based Ir(III) complexes have great potential for fabricating high‐performance red OLEDs.

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Section: Introductionmentioning

confidence: 99%

Diarylboron‐Based Asymmetric Red‐Emitting Ir(III) Complex for Solution‐Processed Phosphorescent Organic Light‐Emitting Diode with External Quantum Efficiency above 28%

et al. 2018

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“…The EQE of the Ir(mphmq) 2 tmd device was higher than that of the devices containing Ir(MDQ) 2 acac, Ir(mphq) 2 acac or fac-Ir(phq) 3 . Specifically, the Ir(mphmq) 2 tmd device showed a very high EQE of 35.6% at a luminance of 350 cd m À 2 , which is 1.5 times higher than the highest efficiency reported to date for red OLEDs and even higher than that of green OLEDs [1][2][3]19,28,29 . The efficiency roll-off was also very small, as the EQE was 35.1% at 1,000 cd m À 2 and 30.0% at 10,000 cd m À 2 .…”

Section: Materials Formentioning

confidence: 91%

Phosphorescent dye-based supramolecules for high-efficiency organic light-emitting diodes

et al. 2014

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Organic light-emitting diodes (OLEDs) are among the most promising organic semiconductor devices. The recently reported external quantum efficiencies (EQEs) of 29-30% for green and blue phosphorescent OLEDs are considered to be near the limit for isotropically oriented iridium complexes. The preferred orientation of transition dipole moments has not been thoroughly considered for phosphorescent OLEDs because of the lack of an apparent driving force for a molecular arrangement in all but a few cases, even though horizontally oriented transition dipoles can result in efficiencies of over 30%. Here we use quantum chemical calculations to show that the preferred orientation of the transition dipole moments of heteroleptic iridium complexes (HICs) in OLEDs originates from the preferred direction of the HIC triplet transition dipole moments and the strong supramolecular arrangement within the co-host environment. We also demonstrate an unprecedentedly high EQE of 35.6% when using HICs with phosphorescent transition dipole moments oriented in the horizontal direction.

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“…Furthermore, red phosphors commonly suffer from much worse triplet-involved quenching effects due to their high polarities, narrow energy gaps, and longer lifetimes, which led to a higher demand for polarized host materials [56]. To a certain extent, it is a benefit that red phosphorescent host materials possess highly polarized and small conjugated systems [57,58]. According to the results of the DFT simulation (Table 2), the FMOs of SFX-DbPy and SFX-TbPy are more separate than the FMO of SFX-bPy.…”

Section: Compoundmentioning

confidence: 99%

Quinolyl functionalized spiro[fluorene-9,9′-xanthene] host materials with bipolar characteristics for green and red phosphorescent organic light-emitting diodes

Ren

Zhong

Sun

et al. 2016

Organic Electronics

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a b s t r a c tSpiro[fluorene-9,9 0 -xanthene] (SFX) bipolar hosts bearing one, two and three quinolyl substituents, namely SFX-bPy, SFX-DbPy and SFX-TbPy, were designed and synthesized for phosphorescent organic light emitting diodes (PhOLEDs). The successive substitution of quinoline at 2 0 , 2 and 7 0 positions of SFX results in reduced LUMO energy levels while leaving the HOMO energy levels nearly intact. The impact of quinoline substitution in these SFX-based hosts on PhOLED performance was investigated in detail through green and red model devices. For the green emitting devices, the device based on SFX-bPy host showed better performance (23.6 cd A À1 , 23.4 lm W À1 , 6.3%) due to high triplet energy level (T 1 ) and balanced carriers-transporting ability. In contrast, for the red PhOLED devices, the device hosted by SFXDbPy displayed higher performance (15.8 cd A À1 , 16.0 lm W À1 , 9.1%), attributable to the well matched T 1 and separated frontier molecular orbitals. This work thus sheds light on the rational design of SFX-based bipolar hosts for more efficient PhOLEDs.

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Host and Dopant Materials for Idealized Deep‐Red Organic Electrophosphorescence Devices

Cited by 195 publications

References 33 publications

Diarylboron‐Based Asymmetric Red‐Emitting Ir(III) Complex for Solution‐Processed Phosphorescent Organic Light‐Emitting Diode with External Quantum Efficiency above 28%

Diarylboron‐Based Asymmetric Red‐Emitting Ir(III) Complex for Solution‐Processed Phosphorescent Organic Light‐Emitting Diode with External Quantum Efficiency above 28%

Phosphorescent dye-based supramolecules for high-efficiency organic light-emitting diodes

Quinolyl functionalized spiro[fluorene-9,9′-xanthene] host materials with bipolar characteristics for green and red phosphorescent organic light-emitting diodes

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