High-efficiency blue phosphorescent organic light-emitting diodes using a carbazole and carboline-based host material

Kim, Sun Jae; Kim, Young Jae; Son, Young Hoon; Hur, Jung A.; Um, Hyun Ah; Shin, Jicheol; Lee, Tae Wan; Cho, Min Ju; Kim, Jung Keun; Joo, Sung-Kwan; Yang, Joong Hwan; Chae, Gee Sung; Choi, Kihang; Kwon, Jang Hyuk; Choi, Dong Hoon

doi:10.1039/c3cc42569j

Cited by 52 publications

(39 citation statements)

References 27 publications

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“…The crude product was purified by silica-gel column chromatography using n-hexane/MC as an eluent to give 84% yield (1.58 g). 1 13 …”

Section: Synthesismentioning

confidence: 97%

“…The MC portion was concentrated and the crude product purified by silica-gel column chromatography using an eluent of n-hexane/MC, to give 81% yield (1.45 g). 13 …”

Section: Synthesismentioning

confidence: 97%

“…To design potential host molecules for high-performance blue PhOLEDs, we varied the position of two carbazole units and one carboline unit, and compared the new materials' performances to that of previously reported pBCb2Cz-containing PhOLED [13]. pP2CZCB and mP2CZCB displayed E T values of 2.92 eV and 2.93 eV, respectively, which are high enough to allow for energy transfer to FIrpic, the blue dopant.…”

Section: Introductionmentioning

confidence: 98%

“…Among the fused heterocycles available for use as effective bipolar hosts [10][11][12][13], carbazole and carboline moieties are particularly favorable, owing to their flexible attachments to specific aromatic core units. Although carboline is similar to carbazole in structure, it has a higher electron affinity because of its electron-deficient pyridine subunit.…”

Section: Introductionmentioning

confidence: 99%

“…In our previous work, we demonstrated a set of bipolar host materials bearing carbazole and carboline moieties [13]. It was found that the 9-(4-(9H-pyrido [2,3-b]indol-9-yl)phenyl)-9H-3,9 0 -bicarbazole (pBCb2Cz) host material showed a promising E T (2.93 eV) for use in blue PhOLEDs, and that a FIrpic-based device exhibited a high EQE of over 20%.…”

Section: Introductionmentioning

confidence: 99%

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Molecular design of large-bandgap host materials and their application to blue phosphorescent organic light-emitting diodes

Kang¹,

Hong²,

Kim³

et al. 2015

Organic Electronics

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“…The crude product was purified by silica-gel column chromatography using n-hexane/MC as an eluent to give 84% yield (1.58 g). 1 13 …”

Section: Synthesismentioning

confidence: 97%

“…The MC portion was concentrated and the crude product purified by silica-gel column chromatography using an eluent of n-hexane/MC, to give 81% yield (1.45 g). 13 …”

Section: Synthesismentioning

confidence: 97%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Molecular design of large-bandgap host materials and their application to blue phosphorescent organic light-emitting diodes

Kang¹,

Hong²,

Kim³

et al. 2015

Organic Electronics

Self Cite

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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

282

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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Orthogonal Molecular Structure for Better Host Material in Blue Phosphorescence and Larger OLED White Lighting Panel

Liu

Dong

Jiang

et al. 2014

Adv Funct Materials

150

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1wileyonlinelibrary.com power effi ciency (PE) >50 lm W −1 and low effi ciency roll-off at 5000 cd m −2 are still rare. [ 5 ] Considering the pursuit of various blue emitters is still ongoing, [ 6 ] it is also necessary to develop new host materials to test different kinds of emitting phosphors. Furthermore, another main application for blue hosts is for the high-effi ciency white light emission; their performances on large-size lighting panels are fascinating but still a blank in recent literature reports. [ 6 ] Therefore, constant efforts should be devoted to developing good host materials that can achieve high efficiency and fl at effi ciency roll-off simultaneously in blue/white PHOLEDs.The compounds with spiro-core are good candidates in constructing bipolar materials for the inherent orthogonal structure of two molecular halves. In addition, this approach can also effi ciently suppress intermolecular interaction by their adamant backbone, resulting in better solubility and cause entanglement in the amorphous state, then hinder recrystallization. [ 7 ] The development of spiro host material, however, is relatively slower as compared with other series of host materials. In 2005, the fi rst example of spiro host materials named SSS based on 9,9′-spirobifl uorene core is reported, which obtained EQE of ≈10% for red phosphorescence. [ 8 ] In 2008, the fi rst spiro bipolar molecule D2ACN integrated with electron-rich diphenylamine and electron-defi cient nitrile is prepared, but the EQE is just slightly improved to 10.8% with PE of 13 lm W −1 as red host material. [ 9 ] To date, there are just several attempts on blue hosts based on spiro-structure and the device performances are moderate. [ 10 ] Recently, we reported a blue host material SSTF based on new STF core, which could achieved a PE of 41.5 lm W −1 and an EQE of 18.7%. [ 11 ] In the STF molecular structure, a triphenylamine moiety is placed in vertical confi guration to fl uorene. This confi guration endows good hole-transporting ability to STF and makes it unnecessary to introduce any other arylamine groups on spiro backbone that always reduces the triplet energy (such as D2ACN). On the other hand, the fl uorene moiety can be further modifi ed by appending electron-deficient groups to enhance bipolar property. Herein, we design and prepare a new spiro host material POSTF by appending phosphine oxide group on the fl uorene moiety. It demonstrates very high EQE and extremely low effi ciency roll-offs for sky-blue (small size) and white (large size) phosphorescent devices. Orthogonal Molecular Structure for Better Host Material in Blue Phosphorescence and Larger OLED White Lighting PanelLei Ding , Shou-Cheng Dong , Zuo-Quan Jiang , * Hua Chen , and Liang-Sheng Liao * High-effi ciency blue phosphorescence devices with external quantum effi ciencies above 25% are developed using a new bipolar host material, diphenyl(10-phenyl-10 H -spiro[acridine-9,9′-fl uoren]-2′-yl)phosphine oxide (POSTF), which is constructed in orthogonal molecular structure with a ...

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High-efficiency blue phosphorescent organic light-emitting diodes using a carbazole and carboline-based host material

Cited by 52 publications

References 27 publications

Molecular design of large-bandgap host materials and their application to blue phosphorescent organic light-emitting diodes

Molecular design of large-bandgap host materials and their application to blue phosphorescent organic light-emitting diodes

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

Orthogonal Molecular Structure for Better Host Material in Blue Phosphorescence and Larger OLED White Lighting Panel

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