Simple Bipolar Molecules Constructed from Biphenyl Moieties as Host Materials for Deep‐Blue Phosphorescent Organic Light‐Emitting Diodes

Fan, Cong; Zhao, Fangchao; Gan, Pei; Yang, Sifen; Liu, Tengxiao; Zhong, Cheng; Ma, Dongge; Qin, Jingui; Yang, Chuluo

doi:10.1002/chem.201103703

Cited by 63 publications

(20 citation statements)

References 53 publications

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“…Over the past two decades, a lot of efforts have been made to demonstrate blue phosphorescent OLEDs (PhOLEDs) with both high external quantum efficiency (EQE) and power efficiency (PE) by tuning the electrical balance, confining the excitons in the emitting layer (EML), and reducing the operating voltage of the devices. For example, a large number of host materials with higher triplet (T 1 ) level than that of a blue emitter have been synthesized for a blue EML, and the mixed host systems or dual EMLs have been utilized to achieve good charge balance and exciton confinement . New electron or hole transporting materials with high T 1 level adjacent to an EML have also been introduced to confine excitons in the EML .…”

Section: Introductionmentioning

confidence: 99%

An Exciplex Forming Host for Highly Efficient Blue Organic Light Emitting Diodes with Low Driving Voltage

Lee

Cheng

Yoo

et al. 2014

Adv Funct Materials

277

141

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361wileyonlinelibrary.com phosphorescent OLEDs (PhOLEDs) with both high external quantum effi ciency (EQE) and power effi ciency (PE) by tuning the electrical balance, confi ning the excitons in the emitting layer (EML), and reducing the operating voltage of the devices. For example, a large number of host materials with higher triplet (T 1 ) level than that of a blue emitter have been synthesized for a blue EML, and the mixed host systems or dual EMLs have been utilized to achieve good charge balance and exciton confi nement. [24][25][26][27][28][29] New electron or hole transporting materials with high T 1 level adjacent to an EML have also been introduced to confi ne excitons in the EML. [ 5,8,18,[30][31][32][33][34] Moreover, the electrical doping in the injection layers and synthesis of organic materials with high mobility and proper energy level were reported to reduce the operating voltage. [ 14,17,23,31,32,34 ] As a result, the highly effi cient blue PhOLED with a maximum EQE of 30% was reported, [ 22 ] but the device showed large effi ciency rolloff at high luminance and high driving voltage. There are still challenging issues to realize blue PhOLEDs with high EQE, PE, and low effi ciency roll-off at the same time.Use of an exciplex forming co-host is a promising approach to resolve the issues. The effi cient energy transfer from an exciplex forming co-host to phosphorescent dye resulted in high effi ciencies approaching the theoretical limits, low driving voltages, and low effi ciency roll-offs, simultaneously, with a simple structured device. [34][35][36][37][38][39][40] Green, orange and red PhOLEDs and a fl uorescent OLED with EQEs over 30% have been reported, [35][36][37][38][39][40][41][42] but these exciplex forming systems are not applicable to blue dopants because of the higher T 1 level of blue dopants than the T 1 level of exciplexes.The following is required for an exciplex forming co-host for effi cient phosphorescent OLEDs: 1) T 1 level of an exciplex has to be lower than those of the consisting molecules in order to confi ne the excitation energy in the exciplex state, not to be transferred to the consisting molecules, and 2) T 1 level of an exciplex has to be higher than that of a phosphorescent dopant to utilize the energy transfer from the exciplex to a blue dopant. However, seeking for an ideal exciplex system meeting the requirements for a blue dopant seemed to be a challenging issue. [43][44][45] The exciplex forming co-host with phosphorescent dopant system has potential to realize highly effi cient phosphorescent organic light emitting didoes (PhOLEDs). However, the exciplex forming co-host for blue phosphorescent OLEDs has been rarely introduced because of higher triplet level of the blue dopant than green and red dopants. In this work, a novel exciplex forming co-host with high triplet energy level is developed by mixing a phosphine oxide based electron transporting material, PO-T2T, and a hole transporting material, N , N ′-dicarbazolyl-3,5-benzene (mCP). Photo-physical analysi...

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Section: Introductionmentioning

confidence: 99%

An Exciplex Forming Host for Highly Efficient Blue Organic Light Emitting Diodes with Low Driving Voltage

Lee

Cheng

Yoo

et al. 2014

Adv Funct Materials

277

141

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“…Consequently, their lowest unoccupied molecular orbital (LUMO) levels determined from the reduction potentials were -2.81 eV for DCB and -3.56 eV for DCA, respectively [22]. On the other hand, their highest occupied molecular orbital (HOMO) levels, deduced from the LUMO and E g , were -6.97 and -6.33 eV for DCB and DCA [23]. Due to the larger aromatic π skeleton, DCA exhibits lower LUMO than DCB and could lead to its better electron conductivity.…”

Section: Resultsmentioning

confidence: 97%

Exploitation of redox-active 1,4-dicyanobenzene and 9,10-dicyanoanthracene as the organic electrode materials in rechargeable lithium battery

Deng

Pei

et al. 2017

Electrochemistry Communications

Self Cite

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A new redox-active family of aromatic dicyanides was developed as organic electrodes in rechargeable batteries. The detailed electronic properties of two primary representatives of 1,4-dicyanobenzene (DCB) and 9,10-dicyanoanthracene (DCA) were studied. It is discovered that, as compared with DCB, the large aromatic π conjugation in DCA leads to better electron conductivity and more stable reduced states of DCAand DCA 2-. The Li-ion batteries with DCA electrode are shown to have highly reversible operations.

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“…The UV/ Vis spectra of both PyOxd-mCz and PyOxd-pCz include three main absorption at the wavelength of 243 nm, 293 nm and 340 nm, corresponding to the transitions of phenyl, carbazolecentered n-p* transition and p-p* transitions of extended p conjunction between the carbazole unit and the central phenyl, respectively. 30 The 340 nm attribution can be veried by the fact that the absorption of 340 nm for PyOxd-pCz is stronger than that of PyOxd-mCz, because the former with less space hinder has longer conjunction line which leads to stronger extended pp* transition and absorption.…”

Section: Thermal Prorertiesmentioning

confidence: 99%

Oxadiazole derivatives as bipolar host materials for high-performance blue and green phosphorescent organic light-emitting diodes

Wang

Duan

et al. 2019

RSC Adv.

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Simple Bipolar Molecules Constructed from Biphenyl Moieties as Host Materials for Deep‐Blue Phosphorescent Organic Light‐Emitting Diodes

Cited by 63 publications

References 53 publications

An Exciplex Forming Host for Highly Efficient Blue Organic Light Emitting Diodes with Low Driving Voltage

An Exciplex Forming Host for Highly Efficient Blue Organic Light Emitting Diodes with Low Driving Voltage

Exploitation of redox-active 1,4-dicyanobenzene and 9,10-dicyanoanthracene as the organic electrode materials in rechargeable lithium battery

Oxadiazole derivatives as bipolar host materials for high-performance blue and green phosphorescent organic light-emitting diodes

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