Co-reporter:Sujin Jeong, Se Hyun Kim, Dong Young Kim, Changmin Kim, Ho Won Lee, Song Eun Lee, Young Kwan Kim, Seung Soo Yoon
Thin Solid Films 2017 Volume 636(Volume 636) pp:
Publication Date(Web):31 August 2017
DOI:10.1016/j.tsf.2017.05.011
•We synthesized blue materials based on dibenzochrysenes.•Dibenzochrysenes showed the highly efficient blue electroluminescent performances.•Dibenzochrysenes have great potential for blue emitters in OLEDs.Three blue materials based on diphenylamino dibenzo[g,p]chrysene were designed and synthesized via Buchwald-Hartwig amination. To characterize their electroluminescent properties, multilayered organic light emitting diodes (OLEDs) were fabricated with the following device structure: indium tin oxide (ITO) (180 nm)/4,4′,4″-tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA) (40 nm)/N,N′-diphenyl-N,N′-(1-napthyl)-(1,1′-phenyl)-4,4′-diamine (NPB) (10 nm)/2-methyl-9,10-di(naphthalen-3-yl)anthracene (mADN): 3 or 7% blue dopants (20 nm)/tris-(8-hydroxyquinoline)aluminum (Alq3) (30 nm)/lithium quinolate (Liq) (2 nm)/Al (100 nm). All the devices showed blue emission with high electroluminescent efficiencies. Particularly, a device using 2-methyl-9,10-di(naphthalen-3-yl)anthracene as the host material and 3,6-di[4′-(1-di(tert-butyl))phenyl]-11,14-bis(diphenylamino) dibenzo[g,p]chrysene (2) as the dopant material at 3% doping exhibited highly efficient blue emission with an external quantum efficiency of 4.72% at 20 mA/cm2.
Co-reporter:Jwajin Kim, Kum Hee Lee, Young Seok Kim, Hyun Woo Lee, Ho Won Lee, Young Kwan Kim, Seung Soo Yoon
Journal of Luminescence 2016 Volume 171() pp:58-62
Publication Date(Web):March 2016
DOI:10.1016/j.jlumin.2015.10.056
We demonstrated triphenylsilane-substituted arenes (1–4) as host materials for green phosphorescent organic light-emitting diodes. Particularly, a device using 9,9-dimethyl-2-(triphenylsilyl)-7-[4-(triphenylsilyl)phenyl]-9H-fluorene (compound 4) as the host material with the green phosphorescence dopant bis[2-(1,1′,2′,1′′-terphen-3-yl)pyridinato-C,N]iridium(III)(acetylacetonate) showed the efficient green emission with an external quantum efficiency of 4.64%, a power efficiency of 7.2 lm/W and luminous efficiency of 16.6 cd/A at 20 mA/cm2, respectively, with the Commission International de L’Eclairage chromaticity coordinates of (0.33, 0.59) at 8.0 V.
Co-reporter:Young Seok Kim;Su Jin Jeong;Hyun Woo Lee;Jwajin Kim;Song Eun Lee;Young Kwan Kim
Luminescence 2016 Volume 31( Issue 4) pp:1031-1036
Publication Date(Web):
DOI:10.1002/bio.3070
Abstract
In this study, we have synthesized phenyl-substituted triphenylene derivatives, using the Diels–Alder reaction and the Buchwald–Hartwig reaction. To investigate electroluminescence properties of these materials, multilayer organic light-emitting diode (OLED) devices were fabricated with a structure of indium–tin–oxide (ITO) (180 nm)/4,4′-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (NPB) (50 nm)/blue-emitting materials (1–3) (30 nm)/bathophenanthroline (Bphen) (35 nm)/lithium quinolate (Liq) (2 nm)/Al (100 nm). A device using N2,N2,N11,N11,5,6,7-heptaphenyltriphenylene-2,11-diamine (2) exhibited efficient blue emission with luminous, power, and external quantum efficiencies of 0.92 cd/A, 0.67 lm/W, and 1.17% at 20 mA/cm2, respectively. The Commission International de L'Éclairage coordinates of this device were (x = 0.15, y = 0.09) at 6.0 V. Copyright © 2015 John Wiley & Sons, Ltd.
Co-reporter:Xu Zheng, Kum Hee Lee, Hongguang Liu, So-Young Park, Seung Soo Yoon, Jin Yong Lee, Yang-Gyun Kim
Sensors and Actuators B: Chemical 2016 Volume 222() pp:28-34
Publication Date(Web):January 2016
DOI:10.1016/j.snb.2015.08.053
A new bis(pyridine-2-ylmethyl)amine derivative (1) was synthesized as a colorimetric and fluorescent chemosensor for metal ions. Experimental results indicate that 1 displays significant colorimetric and fluorescent changes upon binding of Cu2+. Since 1 has a high water solubility as well as good cell-permeability, it successfully applied to detect the presence of Cu2+ ion in HepG2 cells in culture medium. Thus, 1 can be used as a potential Cu2+ chemosensor in aqueous solution and mammalian cells. Further, the fluorescence behavior of 1 upon Cu2+ binding was well explained by our quantum calculation based on electronic structure.
Co-reporter:Ji Young Song, Soo Na Park, Seok Jae Lee, Young Kwan Kim, Seung Soo Yoon
Dyes and Pigments 2015 Volume 114() pp:40-46
Publication Date(Web):March 2015
DOI:10.1016/j.dyepig.2014.11.003
•Anthracene-fluorene derivatives with triphenylsilane groups were synthesized.•Four different emitting cores are used to study the effect of structural variations on the electroluminescence performance of OLED devices.•The introduction of triphenylsilane moieties into the anthracene-fluorene emitting cores provides non-coplanar structure, which effectively inhibits molecular aggregation and excimer formation in the solid state.This paper reports the synthesis and electroluminescence properties of new blue-emitting materials based on anthracene-fluorene derivatives with triphenylsilane groups for organic light-emitting diodes. To study the electroluminescence properties, OLEDs were fabricated in the following sequence: ITO/4,4-Bis(N-(1-naphthyl)-N-phenylamino)biphenyl (50 nm)/newly designed blue materials (30 nm)/4,4-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (30 nm)/8-Hydroxyquinolinolato-lithium (2 nm)/Al (100 nm). All devices exhibited blue electroluminescence. In particular, the device using 10-(9,9-dimethyl-2-(triphenylsilyl)-9H-fluoren-7-yl)-9-(4-(triphenylsilyl)phenyl) anthracene as the emitting material exhibited the deepest blue-emission with CIE coordinates of (x = 0.15, y = 0.09). Also, the device using (9,9-dimethyl-2-(10-(10-phenylanthracen-9-yl)anthracen-9-yl)-9H-fluoren-7-yl)triphenylsilane exhibited high luminous, power and quantum efficiencies of 2.53 cd/A, 1.94 lm/W and 1.72% at 20 mA/cm2, respectively.
Co-reporter:Hyun Woo Lee, Jwajin Kim, Young Seok Kim, Song Eun Lee, Young Kwan Kim, Seung Soo Yoon
Dyes and Pigments 2015 Volume 123() pp:363-369
Publication Date(Web):December 2015
DOI:10.1016/j.dyepig.2015.08.004
•We synthesized blue emitters based on bispiro-type anthracene derivatives.•These materials showed the efficient deep-blue electroluminece.•Bispiro-type emitters have great potential for blue emitters in OLEDs.Three bispiro-type molecules, 2-(10-phenylanthracen-9-yl)-bispiro(9,10-dihydro-anthracene-9,7′-7′H-fluorene-10,7″-7″H-fluorene) (1), 10-([naphthalen-2-yl]anthracen-9-yl)-bispiro(9,10-dihydro-anthracene-9,7′-7′H-fluorene-10,7″-7″H-fluorene) (2), and 10-([naphthalen-1-yl]anthracen-9-yl)-bispiro(9,10-dihydro-anthracene-9,7′-7′H-fluorene-10,7″-7″H-fluorene) (3), were synthesized by Pt-catalyzed Suzuki coupling reactions. To explore electroluminescence properties of these materials, devices were fabricated with the following structures: Indium-tin-oxide (180 nm)/4,4′-Bis(N-(1-naphthyl)-N-phenylamino)biphenyl (60 nm)/blue emitting materials (30 nm)/Bathophenanthroline (30 nm)/Lithium quinolate (2 nm)/Al (100 nm). Among devices, device using 2-(10-phenylanthracen-9-yl)-bispiro(9,10-dihydro-anthracene-9,7′-7′H-fluorene-10,7″-7″H-fluorene) showed the efficient blue emission with a luminous efficiency of 1.57 cd/A, a power efficiency of 1.83 lm/W and an external quantum efficiency of 1.83% at 20 mA/cm2, respectively. The CIE coordinates of this device were (0.16, 0.10).
Co-reporter:Jwajin Kim, Se Hyun Kim, Ho Won Lee, Song Eun Lee, Young Kwan Kim and Seung Soo Yoon
New Journal of Chemistry 2015 vol. 39(Issue 7) pp:5548-5552
Publication Date(Web):13 May 2015
DOI:10.1039/C5NJ00929D
Two host materials based on the carbazole/pyridine end-capping group were designed and synthesized to produce green phosphorescent organic light-emitting diodes. One of the host materials, 9-[9,9-diethyl-2-(6-methylpyridin-2-yl)-9H-fluoren-7-yl]-9H-carbazole (2), exhibited excellent properties for use in efficient green phosphorescent organic light-emitting diodes. A device using compound 2 as the host material with the green phosphorescence dopant bis[2-(1,1′,2′,1′′-terphen-3-yl)pyridinato-C,N]iridium(III)(acetylacetonate) had an external quantum efficiency of 10.7%, a power efficiency of 17.27 lm W−1 and a luminance efficiency of 39.72 cd A−1 at 20 mA cm−2, with CIE chromaticity coordinates of (0.34, 0.62) at 8.0 V.
Co-reporter:Hyun Woo Lee, Hye Jeong Kim, Young Seok Kim, Jwajin Kim, Song Eun Lee, Ho Won Lee, Young Kwan Kim, Seung Soo Yoon
Journal of Luminescence 2015 Volume 165() pp:99-104
Publication Date(Web):September 2015
DOI:10.1016/j.jlumin.2015.04.029
•We synthesized fluorescent materials based on phenylanthracene derivatives.•Electroluminescence properties of these materials depend on the molecular structures.•These blue and white materials have great potential for application in OLEDs.This study reports the emitting materials based on phenylanthracene-substituted naphthalene derivatives to achieve efficient electroluminescent properties for OLED applications. An OLED device using 4,4′-bis(10-phenylanthracen-9-yl)-1,1′-binaphthalene exhibited the blue emission with the CIE coordinates of (0.19, 0.16) and efficient electroluminescent properties with the luminance, power and external quantum efficiency of 1.70 cd/A, 0.79 lm/W and 1.26% at 20 mA/cm2, respectively. Also, the other device using 1,4-bis(10-phenylanthracene-9-yl)naphthalene exhibited white emission with the CIE coordinates of (0.34, 0.43) at 7V, respectively. This device exhibits the luminance, power and external quantum efficiency of 2.22 cd/A, 1.13 lm/W and 0.86% at 20 mA/cm2, respectively.
Co-reporter:Soo Na Park, Hyun Woo Lee, Young Seok Kim, Jwajin Kim, Song Eun Lee, Ho Won Lee, Young Kwan Kim, Seung Soo Yoon
Synthetic Metals 2015 Volume 206() pp:124-130
Publication Date(Web):August 2015
DOI:10.1016/j.synthmet.2015.05.020
•We synthesized fluoranthene and triphenylene derivatives.•The EL efficiencies of materials depend on the degree of self-aggregation.•These materials have great potential for applications as blue emitter in OLEDs.In this study, we have designed and synthesized blue emitters based on fluoranthene and triphenylene via Diels–Alder reaction. To investigate EL properties, multilayered OLEDs were fabricated by using these materials as emitting materials. The device structure was ITO / NPB / (50 nm) / Blue emitting materials (30 nm) / Bphen (30 nm) / Liq (2 nm) / Al. In particular, a device showed blue EL properties with luminous, power, and external quantum efficiencies of 2.34 cd/A, 1.18 lm/W, 1.36% at 20 mA/cm2, and the CIE coordinates of (0.17, 0.23) at 6 V, respectively. The balanced charge injection properties of devices as well as the nonplanar structures of the emitting materials have the profound effects on the EL efficiencies.
Co-reporter:Seul Bee Lee, Soo Na Park, Chanwoo Kim, Hyun Woo Lee, Ho Won Lee, Young Kwan Kim, Seung Soo Yoon
Synthetic Metals 2015 Volume 203() pp:174-179
Publication Date(Web):May 2015
DOI:10.1016/j.synthmet.2015.02.037
•Anthracene derivatives end-capped with the various carbazole groups were synthesized.•Four materials are used to study the effect of structural variations on OLED devices.•The EL of these materials as dopants depend on the effective energy transfer from host material.Four novel molecules, 9-(9,10-diphenylanthracen-3-yl)-9H-carbazole (1), 7-(9,10-diphenylanthracen-3-yl)-7H-benzo[c]carbazole (2), 7-(9,10-diphenylanthracen-3-yl)-7H-benzo[e]pyrido[3,2-b]indole (3), 7-(9,10-diphenyl-2-(7H-benzo[e]pyrido[3,2-b]indol-7-yl)anthracen-6-yl)-7H-benzo[e]pyrido[3,2-b]indole (4), based on 9,10-diphenylanthracene with carbazole derivatives, were designed and synthesized via Buchwald–Hartwig cross-coupling reactions. Multilayer OLED devices were fabricated with the following device structure: ITO/2-TNATA (60 nm)/NPB (20 nm)/α,β-ADN:blue dopant materials (10%, 30 nm)/DNAB (30 nm)/Liq:Al. Among those, the device using 1 exhibited the efficient blue emission with a luminous efficiency of 4.56 cd/A, power efficiency of 1.95 lm/W, an external quantum efficiency of 3.42%, and CIE x,y coordinates of (0.15, 0.17) at 20 mA/cm2, respectively.
Co-reporter:Young Seok Kim, Jhin-yeong Yoon, Hyun Woo Lee, Jwajin Kim, Ho Won Lee, Song Eun Lee, Young Kwan Kim, Seung Soo Yoon
Optical Materials 2015 Volume 46() pp:247-253
Publication Date(Web):August 2015
DOI:10.1016/j.optmat.2015.04.027
•We synthesized blue emitters based on bis(10-phenylanthracen-9-yl)heterocycle.•The EL performances of these materials rely on the reduced molecular interaction.•These materials have good latent ability for applications in blue fluorescent OLEDs.We synthesized a series of bis(10-phenylanthracen-9-yl) derivatives containing various heterocyclic moieties such as 9-ethylcarbazole, dibenzofuran and dibenzothiophene (1–3) by Suzuki cross-coupling reactions. To explore electroluminescent properties of these materials, multilayered devices were fabricated with configuration of indium–tin–oxide (ITO) (180 nm)/4,4′-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (NPB) (50 nm)/Emitters 1–3 (30 nm)/Tris(8-hydroxyquinolinato) aluminium (Alq3) (15 nm)/lithium quinolate (Liq) (2.0 nm)/Al (100 nm). In particular, a device using 2,8-bis(10-phenylanthracen-9-yl)dibenzo[b,d]furan (2), as an emitter, exhibited efficient blue emission with maximum luminance, luminous, power and external quantum efficiency of 620 cd/m2, 2.05 cd/A, 1.05 lm/W, 1.43% at 20 mA/cm2, and CIE coordinates of (x = 0.18, y = 0.17) at 8 V, respectively.
Co-reporter:Hyun Woo Lee, Hye Jeong Kim, Young Seok Kim, Jwajin Kim, Song Eun Lee, Ho Won Lee, Young Kwan Kim, Seung Soo Yoon
Displays 2015 Volume 39() pp:1-5
Publication Date(Web):October 2015
DOI:10.1016/j.displa.2015.05.003
•We synthesized blue fluorescent materials based on anthracene–fluorene hybrid.•These materials have the good potentials for efficient blue OLEDs as the emitters.•A white OLED using one of these materials as blue emitter was demonstrated.Two phenylanthracene-substituted fluorene derivatives, 10-(9,9′-dimethyl-2-(10-phenylanthracen-9-yl)-9H-fluoren-7-yl)-phenylanthracene (1) and 2′,7′-di-(10-phenylanthracen-9-yl)-9,9′-spirobi[9H-fluorene] (2) have been designed, synthesized, and characterized. A device using compound 1 as an emitting material exhibited luminous efficiency, power efficiency, external quantum efficiency and CIE coordinates of 3.37 cd/A, 1.50 lm/W, 1.87% at 20 mA/cm2 and (0.18, 0.25) at 7 V, respectively. Furthermore, by exploiting this efficient blue fluorescent material as a blue emitting material with the combination of red phosphorescent bis(2-phenylquinoline)acetylacetonate [(pq)2Ir(acac)], an efficient white OLED (WOLED) with a external quantum efficiency of 1.70%, luminous efficiency of 1.38 cd/A, power efficiency of 0.94 lm/W at 20 mA/cm2 and the color coordinates of (0.33, 0.36) at 14 V is demonstrated.
Co-reporter:Ji Young Song, Seul Bee Lee, Seok Jae Lee, Young Kwan Kim, Seung Soo Yoon
Thin Solid Films 2015 Volume 577() pp:42-48
Publication Date(Web):27 February 2015
DOI:10.1016/j.tsf.2015.01.050
•We synthesized 9-(2-naphthyl)anthracene derivatives with a triphenylsilane unit.•We study the conjugation-length effect on the electroluminescence properties.•The bulky triphenylsilane-anthracene derivatives show resistance to self-aggregation.A series of 9-(2-naphthyl)anthracene derivatives with a triphenylsilane unit, which prevented molecular aggregation and self-quenching effect, was designed and synthesized. By using various bridges between the 9-(2-naphthyl)anthracene group and the triphenylsilane unit, five deep-blue emitters were obtained and applied as non-doped emitting materials in organic light-emitting diodes (OLEDs) with a device structure of indium–tin-oxide (ITO) (180 nm)/4,4-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (NPB) (50 nm)/emitting materials (30 nm)/4,7-diphenyl-1,10-phenanthroline (Bphen) (30 nm)/lithium quinolate (Liq) (2 nm)/Aluminium (100 nm). All devices showed blue emissions and their electroluminescence efficiencies are sensitive to the structural changes of the emitting materials. In particular, a device using 9-(2-naphthalenyl)-10-[6-(triphenylsilyl)-2-naphthalenyl]-anthracene (4) exhibited high luminous, power and quantum efficiencies of 2.28 cd/A, 1.42 lm/W and 2.40% at 20 mA/cm2, respectively, and this device showed the deep blue emission with the CIE coordinates of (0.16, 0.10) at 6.0 V.
Co-reporter:Ji Young Song, Seok Jae Lee, Young Kwan Kim, Seung Soo Yoon
Materials Research Bulletin 2014 58() pp: 145-148
Publication Date(Web):
DOI:10.1016/j.materresbull.2014.03.021
Co-reporter:Jhin-yeong Yoon, Eun Jae Na, Soo Na Park, Seok Jae Lee, Young Kwan Kim, Seung Soo Yoon
Materials Research Bulletin 2014 58() pp: 149-152
Publication Date(Web):
DOI:10.1016/j.materresbull.2014.03.019
Co-reporter:Seok Jae Lee;Ja Ryong Koo;Ho Won Lee;Song Eun Lee
Electronic Materials Letters 2014 Volume 10( Issue 6) pp:1127-1131
Publication Date(Web):2014 November
DOI:10.1007/s13391-014-4132-4
Co-reporter:Heung Soo Jang;Kum Hee Lee;Seok Jae Lee;Young Kwan Kim
Electronic Materials Letters 2013 Volume 9( Issue 6) pp:759-761
Publication Date(Web):2013 November
DOI:10.1007/s13391-013-6007-5
A red fluorescent compound, 4-(dicyanomethylene)-2-(1-pentylbicyclo[2,2,2]oct-4-yl)-6-(1-adamantyl-1,7,7-trimethyljulolidyl-9-enyl)-4H-pyran containing bulky adamantyl and 1-pentylbicyclo[2,2,2]octyl groups on a DCM backbone, was synthesized and characterized. In a red device using this material as a dopant, a luminous and power efficiency of 3.21 cd/A and 1.68 lm/W was achieved, respectively, at 20 mA/cm2 with the CIE coordinates of (x = 0.60, y = 0.39) at 7.0 V.
Co-reporter:Ja Ryong Koo, Seok Jae Lee, Gun Woo Hyung, Bo Young Kim, Dong Hyung Lee, Woo Young Kim, Kum Hee Lee, Seung Soo Yoon, Young Kwan Kim
Thin Solid Films 2013 Volume 544() pp:234-237
Publication Date(Web):1 October 2013
DOI:10.1016/j.tsf.2013.03.113
•Highly efficient phosphorescent white organic light-emitting diode (WOLED)•Single emitting layer consists of synthesized deep blue host and orange emitter•The WOLED with high EL efficiencies due to efficient triplet exciton confinementThe authors have demonstrated a highly efficient and stable phosphorescent white organic light-emitting diode (WOLED), which has been achieved by doping only one orange phosphorescent emitter, Bis(5-benzoyl-2-(4-fluorophenyl)pyridinato-C,N)iridium(III) acetylacetonate into an appropriate deep blue phosphorescent host, 4,4'-bis(4-(triphenylsilyl)phenyl)-1,1'-binaphthyl as an emitting layer (EML). The WOLED has been achieved by effective confinement of triplet excitons to emit a warm white color. The optimized WOLED, with a simple structure as a hole transporting layer-EML-electron transporting layer, showed a maximum luminous efficiency of 22.38 cd/A, a maximum power efficiency of 12.01 lm/W, a maximum external quantum efficiency of 7.32%, and CIEx,y coordinates of (0.38,0.42) at 500 cd/m2, respectively.
Co-reporter:Kum Hee Lee, Seul Ong Kim, Jae Nam You, Sunwoo Kang, Jin Yong Lee, Kyoung Soo Yook, Soon Ok Jeon, Jun Yeob Lee and Seung Soo Yoon
Journal of Materials Chemistry A 2012 vol. 22(Issue 11) pp:5145-5154
Publication Date(Web):03 Feb 2012
DOI:10.1039/C2JM14869B
A series of tert-butylated spirofluorene derivatives incorporating a diphenylaminoaryl-vinyl group was synthesized via the Horner–Wadsworth–Emmons olefination and a Suzuki cross-coupling reaction. To examine the electroluminescent properties of these materials, multilayered OLEDs were fabricated into the following device structure: ITO/DNTPD/NPB/MADN:blue dopant materials 1–14/Alq3/Liq/Al. All devices showed efficient blue emission. In particular, one device exhibited highly efficient sky blue emission with a maximum luminance of 25100 cd m−2 at 8.5 V, as well as luminous, power and external quantum efficiencies of 9.5 cd A−1, 5.1 lm W−1 and 6.7% at 20 mA cm−2, respectively. The peak wavelength of electroluminescence was 458 and 484 nm with CIEx,y coordinates of (0.14, 0.21) at 8.0 V. In addition, a deep blue device with CIEx,y coordinates of (0.15, 0.15) at 8.0 V showed a luminous efficiency and external quantum efficiency of 3.8 cd A−1 and 3.3% at 20 mA cm−2, respectively.
Co-reporter:Kum Hee Lee;Seul Ong Kim;Sunwoo Kang;Jin Yong Lee;Kyoung Soo Yook;Jun Yeob Lee
European Journal of Organic Chemistry 2012 Volume 2012( Issue 14) pp:2748-2755
Publication Date(Web):
DOI:10.1002/ejoc.201200117
Abstract
Blue fluorescent compounds based on indenofluorene derivatives incorporating the (diphenylamino)arylvinyl group and di-tert-butylphenyl blocking units have been synthesized by Suzuki coupling and the Horner–Wadsworth–Emmons reaction. Their electroluminescence in multilayered OLEDs was examined; the devices have the structures ITO/DNTPD/NPB/MADN:blue dopant/Alq3/LiF/Al. A device with 7 % 2-(3,5-di-tert-butylphenyl)-8-(9,9-diethyl-2-(diphenylamino)fluoren-7-ylethenyl)-6,6,12,12-tetraethylindeno[1,2-b]fluorene (3) as blue dopant showed a luminous efficiency of 12.2 cd A–1, a power efficiency of 6.08 lm W–1, and an external quantum efficiency of 7.84 % at 20 mA cm–1 with CIE (Commission Internationale d'Énclairage) (x, y) coordinates of (0.148, 0.241) at 8.5 V. A deep-blue OLED with CIE (x, y) coordinates of (0.153, 0.128) doped with 2-(3,5-di-tert-butylphenyl)-8-[9-(3,5-di-tert-butylphenyl)carbazol-3-ylethenyl]-6,6,12,12-tetraethylindeno[1,2-b]fluorene (4) exhibited a luminous efficiency of 3.25 cd A–1, a power efficiency of 1.74 lm W–1, and an external quantum efficiency of 2.93 % at 20 mA cm–1.
Co-reporter:Kum Hee Lee, Hyun Ju Kang, Seok Jae Lee, Young Kwan Kim, Seung Soo Yoon
Synthetic Metals 2012 Volume 162(7–8) pp:715-721
Publication Date(Web):May 2012
DOI:10.1016/j.synthmet.2012.02.008
Red phosphorescent emitters for OLEDs were synthesized using Ir(III) complexes based on 5-benzoyl-2-phenylpyridine ligands with fluorine and methyl substitution. Their electroluminescence, when doped in the emitting layers of multilayer OLEDs, was sensitive to their structural features. In particular, a highly efficient orange-red OLED showed a maximum luminance of 18,740 cd/m2 at 11 V, with a luminous efficiency of 25.9 cd/A, power efficiency of 8.74 lm/W, external quantum efficiency of 9.25% at 20 mA/cm2, and CIEx,y coordinates of (0.53, 0.47) at 8.0 V, respectively. A red OLED with CIEx,y coordinates of (0.66, 0.34) at 8.0 V exhibited a luminous efficiency, power efficiency and external quantum efficiency of 5.98 cd/A, 2.06 lm/W and 5.77% at 20 mA/cm2, respectively.Graphical abstractHighlights► We develop Ir complexes with 5-benzoyl-2-phenylpyridine derivatives as ligands. ► We examine changes in fluorine and methyl groups in the phenyl moiety. ► These fluorine and methyl groups allow tuning of the band gap of Ir complexes, leading to improved color purity.
Co-reporter:Suhyun Oh, Kum Hee Lee, Young Kwan Kim, Seung Soo Yoon
Materials Research Bulletin 2012 47(10) pp: 2792-2795
Publication Date(Web):
DOI:10.1016/j.materresbull.2012.04.055
Co-reporter:Kum Hee Lee, Jeong Keun Park, Ji Hoon Seo, Se Won Park, Young Sik Kim, Young Kwan Kim and Seung Soo Yoon
Journal of Materials Chemistry A 2011 vol. 21(Issue 35) pp:13640-13648
Publication Date(Web):08 Aug 2011
DOI:10.1039/C1JM12097B
A series of anthracene derivatives with a triphenylsilane end-capping group, (9,9-dimethyl-2-(10-phenylanthracen-9-yl)-9H-fluoren-7-yl)triphenylsilane (PAFTPS), 9,10-bis(9,9-dimethyl-2-(triphenylsilyl)-9H-fluoren-7-yl)anthracene (BFPSA), (9,9-dimethyl-2-(9,10-diphenylanthracen-2-yl)-9H-fluoren-7-yl)triphenylsilane (DPA-2FTPS), and (9,10-eiphenylanthracen-2-yl)triphenylsilane (DPA-2TPS), have been designed, synthesized, and characterized. A device incorporating PAFTPS as the emissive layer exhibited a high external quantum efficiency of 2.02% at 20 mA cm−2 with color coordinates of (0.152, 0.072) as a non-doped blue emitter. At even higher efficiency, an external quantum efficiency up to 2.32% at 20 mA cm−2 with color coordinates of (0.155, 0.076) was obtained when doped with the blue fluorescent material, 3-(N-phenylcarbazol)vinyl-p-terphenyl (PCVtPh). Furthermore, an efficient white OLED with an external quantum efficiency, a luminous efficiency and color coordinates of 4.18%, 9.14 cd A−1 at 1000 cd m−2 and (0.43, 0.41) at 1000 cd m−2 was demonstrated by exploiting this highly efficient blue fluorescent material (PAFTPS) as a host in the blue emitting layer.
Co-reporter:Kum Hee Lee;Chang Seok Son;Jin Yong Lee;Sunwoo Kang;Kyoung Soo Yook;Soon Ok Jeon;Jun Yeob Lee
European Journal of Organic Chemistry 2011 Volume 2011( Issue 25) pp:4788-4798
Publication Date(Web):
DOI:10.1002/ejoc.201100472
Abstract
Highly efficient blue fluorescent materials with a 2-diphenylaminofluoren-7-ylstyrene emitting unit and various aromatic end-capping groups were synthesized and characterized. A 2-methyl-9,10-bis(2-naphthyl)anthracene host was doped with these blue materials as the blue dopants in the emitting layer of organic light-emitting diode (OLED) devices. All devices exhibited highly efficient blue electroluminescence with high external quantum efficiency (4.38–6.2 % at 20 mA cm–2). In particular, two deep blue OLEDs using 7-[3,5-bis(naphthalen-1-yl)styryl]-9,9-diethyl-2-N,N-diphenylamino-9H-fluorene (1f) and 7-{4-[1′-(2′,3′,4′,5′-tetraphenyl)phenyl]styryl}-9,9-diethyl-2-N,N-diphenylamino-9H-fluorene (1g) as dopants in the emitting layer showed high external quantum efficiencies of 4.63 and 5.96 % at 20 mA cm–2 with the color coordinates (0.148, 0.134) and (0.147, 0.144), respectively. A sky-blue OLED using7-{4-[9,9′-spirobi(fluoren)-2-yl]styryl}-9,9-diethyl-2-N,N-diphenylamino-9H-fluorene (1e) exhibited a high quantum efficiency of 6.20 % at 20 mA cm–2 with the color coordinates (0.148, 0.195). Moreover, efficient white OLEDs with an external quantum efficiency, luminous efficiency, and color coordinates of 6.50 %, 10.3 cd A–1 at 20 mA cm–2 and (0.357, 0.310) at 1000 cd m–2 were demonstrated by exploiting this highly efficient blue fluorescent material (1e) as a dopant in the blue-emitting layer.
Co-reporter:Kum Hee Lee, Hyun Ju Kang, Seok Jae Lee, Ji Hyun Seo, Young Kwan Kim, Seung Soo Yoon
Synthetic Metals 2011 Volume 161(11–12) pp:1113-1121
Publication Date(Web):June 2011
DOI:10.1016/j.synthmet.2011.03.030
A series of new iridium complexes with 5-acetyl-2-phenylpyridine derivatives as ligands was developed. The complexes exhibited high EL performance when applied to OLEDs. These materials showed red emission with a peak at 575–636 nm. In particular, one of the devices in this study showed a maximum luminous efficiency, maximum power efficiency, external quantum efficiency and CIE coordinates of 29.0 cd/A, 6.13 lm/W, 8.86% at 20 mA/cm2 and (0.57, 0.43) at 10 V, respectively. In addition, a deep red OLED with CIE coordinates of (0.67, 0.32) at 10 V exhibited a maximum luminous efficiency, maximum power efficiency and external quantum efficiency of 5.61 cd/A, 1.02 lm/W and 5.35% at 20 mA/cm2, respectively.Graphical abstractHighlights► We develop six Ir(III) complexes with 5-acetyl-2-phenylpyridine derivatives as ligands. ► We examine changes in increase of π-conjugation in the phenyl moiety. ► Increasing π-conjugation will improve color purity. ► These new Ir(III) complexes (1–6) possess highly efficient electroluminescent properties.
Co-reporter:Kum Hee Lee, Seul Ong Kim, Kyoung Soo Yook, Soon Ok Jeon, Jun Yeob Lee, Seung Soo Yoon
Synthetic Metals 2011 Volume 161(17–18) pp:2024-2030
Publication Date(Web):September 2011
DOI:10.1016/j.synthmet.2011.07.020
A series of blue fluorescent emitters based on spirofluorene were synthesized via the Horner–Wadsworth–Emmons reaction in moderate yields. Multilayered OLEDs were fabricated with a device structure of ITO/DNTPD (60 nm)/NPB (30 nm)/MADN: Blue dopant materials 1–5 (30 nm)/Alq3 (20 nm)/LiF (1.0 nm)/Al (200 nm). All devices showed efficient blue emission. Among those, device using compound 1 as a dopant material give the best performance with high brightness (2778 cd/m2 at 8.5 V) and high efficiency (4.9 cd/A, 2.3 lm/W, and 4.0% EQE at 20 mA/cm2). The peak wavelength of electroluminescence was 473 nm with CIEx,y coordinates of (0.15, 0.17) at 8.5 V. A deep blue device with CIEx,y coordinates of (0.15, 0.12) at 8.5 V showed a luminous efficiency of 1.8 cd/A and an external quantum efficiency of 1.9% at 20 mA/cm.Graphical abstractHighlights► We develop five blue fluorescent emitters with triphenylamine/phenylcarbazole-substituted spirofluorene derivatives. ► We examine changes in position of spirobifluorene in the terminal groups. ► These blue-emitting materials (1–5) possess highly efficient electroluminescent properties.
Co-reporter:Hyun Ju Kang, Kum Hee Lee, Seok Jae Lee, Ji Hyun Seo, Young Kwan Kim, Seung Soo Yoon
Thin Solid Films 2011 Volume 519(Issue 19) pp:6544-6549
Publication Date(Web):29 July 2011
DOI:10.1016/j.tsf.2011.04.121
A series of phosphorescent Ir(III) complexes 1–4 were synthesized based on aryl(6-arylpyridin-3-yl)methanone ligands, and their photophysical and electroluminescent properties were characterized. Multilayer devices with the configuration, Indium tin oxide/4,4′,4″-tris(N-(naphthalene-2-yl)-N-phenyl-amino)triphenylamine (60 nm)/4,4′-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (20 nm)/Ir(III) complexes doped in N,N′-dicarbazolyl-4,4′-biphenyl (30 nm, 8%)/2,9-dimethyl-4,7-diphenyl-phenathroline (10 nm)/tris(8-hydroxyquinoline)-aluminum (20 nm)/lithium quinolate (2 nm)/ Al (100 nm), were fabricated. Among these, the device employing complex 2 as a dopant exhibited efficient red emission with a maximum luminance, luminous efficiency, power efficiency and quantum efficiency of 16200 cd/m2 at 14.0 V, 12.20 cd/A at 20 mA/cm2, 4.26 lm/W and 9.26% at 20 mA/cm2, respectively, with Commission Internationale de l'Énclairage coordinates of (0.63, 0.37) at 12.0 V.
Co-reporter:Dr. Kum Hee Lee;Young Soo Kwon; Jin Yong Lee;Sunwoo Kang;Kyoung Soo Yook;Soon Ok Jeon; Jun Yeob Lee; Seung Soo Yoon
Chemistry - A European Journal 2011 Volume 17( Issue 46) pp:12994-13006
Publication Date(Web):
DOI:10.1002/chem.201100304
Abstract
Blue fluorescent materials with a 2-(diphenylamino)fluoren-7-ylvinylarene emitting unit and tert-butyl-based blocking units were synthesized. The photophysical properties of these materials, including UV/Vis absorption, photoluminescent properties, and HOMO–LUMO energy levels, were characterized and rationalized with quantum-mechanical DFT calculations. The electroluminescent properties of these molecules were examined through the fabrication of multilayer devices with a structure of indium–tin oxide, 4,4′-bis{N-[4-(N,N-di-m-tolylamino)phenyl]-N-phenylamino}biphenyl, 4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl, and blue materials doped in 2-methyl-9,10-di(2-naphthyl)anthracene/tris(8-quinolinolato)aluminum/LiF/Al. All devices exhibit highly efficient blue electroluminescence with high external quantum efficiency (3.20–7.72 % at 20 mA cm−2). A deep-blue device with Commission Internationale de l’Eclairage (CIE) coordinates of (0.15, 0.11) that uses 7-[2-(3′,5′-di-tert-butylbiphenyl-4-yl)vinyl]-9,9-diethyl-2-N-(3,5-di-tert-butylphenyl)-2,4-difluorobenzenamino-9H-fluorene as a dopant in the emitting layer showed a luminous efficiency and external quantum efficiency of 3.95 cd A−1 and 4.23 % at 20 mA cm−2, respectively. Furthermore, a highly efficient sky-blue device that uses the dopant 7-{2-[2-(3,5-di-tert-butylphenyl)-9,9′-spirobifluorene-7-yl]vinyl}-9,9-diethyl-2-N,N-diphenylamino-9H-fluorene exhibited a luminous efficiency and high quantum efficiency of 10.3 cd A−1 and 7.7 % at 20 mA cm−2, respectively, with CIE coordinates of (0.15, 0.20).
Co-reporter:Kum Hee Lee, Min Hye Park, Chi Sik Kim, Young Kwan Kim, Seung Soo Yoon
Thin Solid Films 2011 Volume 520(Issue 1) pp:510-514
Publication Date(Web):31 October 2011
DOI:10.1016/j.tsf.2011.07.045
Efficient red fluorescent compounds Red 1 and Red 2 based on bulky bicyclo[2,2,2]octane groups in the pyran moiety and tert-butyl or isopropyl group in the julolidine moiety of the 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetra-methyljulolidyl-9-enyl)-4H-pyran (DCJTB) skeleton were synthesized and characterized. As red-emitting dopants in an Alq3 single-host emitting system, Red 1 and Red 2 exhibited improved color purity and enhanced luminous efficiency compared to DCJTB. Moreover, a device using Red 1 as a dopant in a rubrene–Alq3 co-host emitting system exhibited improved electroluminescence performance with a luminous efficiency and power efficiency of 6.89 cd/A and 3.09 lm/W at 20 mA/cm2, respectively, and CIE x,y coordinates of (x = 0.64,y = 0.36) at 7.0 V, approaching saturated red emission.
Co-reporter:Kum Hee Lee, Jae Nam You, Jiyeon Won, Jin Yong Lee, Ji Hoon Seo, Young Kwan Kim, Seung Soo Yoon
Thin Solid Films 2011 Volume 520(Issue 1) pp:95-100
Publication Date(Web):31 October 2011
DOI:10.1016/j.tsf.2011.06.054
This paper reports the synthesis and electroluminescent properties of a series of blue emitting materials with arylamine and diphenylvinylbiphenyl groups for applications to efficient blue organic light-emitting diodes (OLEDs). All devices exhibited blue electroluminescence with electroluminescent properties that were quite sensitive to the structural features of the dopants in the emitting layers. In particular, the device using dopant 4 exhibited sky-blue emission with a maximum luminance, luminance efficiency, power efficiency, external quantum efficiency and CIE coordinates of 39,000 cd/m2, 12.3 cd/A, 7.45 lm/W, 7.71% at 20 mA/cm2 and (x = 0.17, y = 0.31) at 8 V, respectively. In addition, a blue OLED using dopant 2 with CIE coordinates (x = 0.16, y = 0.18) at 8 V exhibited a luminous efficiency, power efficiency and external quantum efficiency of 4.39 cd/A, 2.46 lm/W and 2.97% at 20 mA/cm2, respectively.
Co-reporter:Kum Hee Lee;Lee Kyung Kang;Jin Yong Lee;Sunwoo Kang;Soon Ok Jeon;Kyoung Soo Yook;Jun Yeob Lee
Advanced Functional Materials 2010 Volume 20( Issue 8) pp:1345-1358
Publication Date(Web):
DOI:10.1002/adfm.200901895
Abstract
Blue fluorescent materials based on silicone end-capped 2-diphenylaminofluorene derivatives are synthesized and characterized. These materials are doped into a 2-methyl-9,10-di-[2-naphthyl]anthracene host as blue dopant materials in the emitting layer of organic light-emitting diode devices bearing a structure of ITO/DNTPD (60 nm)/NPB (30 nm)/emitting layer (30 nm)/Alq3 (20 nm)/LiF (1.0 nm)/Al (200 nm). All devices exhibit highly efficient blue electroluminescence with high external quantum efficiencies (3.47%–7.34% at 20 mA cm−2). The best luminous efficiency of 11.2 cd A−1 and highest quantum efficiency of 7.34% at 20 mA cm−2 are obtained in a device with CIE coordinates (0.15, 0.25). A deep-blue OLED with CIE coordinates (0.15, 0.14) exhibits a luminous efficiency of 3.70 cd A−1 and quantum efficiency of 3.47% at 20 mA cm−2.
Co-reporter:Ji Hoon Seo, Seok Jae Lee, Bo Min Seo, Se Jin Moon, Kum Hee Lee, Jung Keun Park, Seung Soo Yoon, Young Kwan Kim
Organic Electronics 2010 Volume 11(Issue 11) pp:1759-1766
Publication Date(Web):November 2010
DOI:10.1016/j.orgel.2010.07.015
The authors have demonstrated white organic light-emitting diodes (WOLED) using all phosphorescent emitters for blue, green, and red, such as FCNIrpic, Ir(ppy)3 and Ir(pq)2(acac). Various electron-transporting materials such as Bebq2, BPhen, TAZ, BAlq, and TPBI were also investigated for improving quantum efficiency of phosphorescence of WOLED by fabricating and characterizing white devices using these materials as an electron-transporting layer (ETL). It was found that WOLED with an ETL of TPBI exhibits a peak external quantum efficiency (EQE) of 19.5% and a peak power efficiency of 39.2 lm/W at very low light intensity. The optimized device also shows an EQE of 16.4% at 1000 cd/m2. It was also found that the optimized white device with TPBI shows minimal change with Δ Commission Internationale de I’Eclairage coordinates of ±(0.02, 0.00) from 100 to 10,000 cd/m2. In order to understand the mechanism for achieving nearly 100% IQE with this device structure, various analyses were also executed, such as UV/visible absorbance measurements of FCNIrpic and photoluminance (PL) measurements of mCP, fabrications of hole- and electron-only devices, UV/visible absorbance measurements of Ir(ppy)3 and Ir(pq)2(acac) and PL of FCNIrpic, and surface roughness measurements of various ETL films.
Co-reporter:Jeong Keun Park, Kum Hee Lee, Sunwoo Kang, Jin Yong Lee, Jung Sun Park, Ji Hoon Seo, Young Kwan Kim, Seung Soo Yoon
Organic Electronics 2010 Volume 11(Issue 5) pp:905-915
Publication Date(Web):May 2010
DOI:10.1016/j.orgel.2010.02.009
A series of new blue-emitting materials: 2-(10-(naphthalen-2-yl)anthracen-9-yl)pyridine (1); 1-(10-(naphthalen-2-yl)anthracen-9-yl)isoquinoline (2); 9-(3-(10-(naphthalen-2-yl)anthracen-9-yl)phenyl)-9H-carbazole (3); 9-(4-(10-(naphthalen-2-yl)anthracen-9-yl)phenyl)-9H-carbazole (4); 9-(4-(10-(naphthalen-1-yl)anthracen-9-yl)phenyl)-9H-carbazole (5); 9-(4′-(10-(naphthalen-2-yl)anthracen-9-yl)biphenyl-4-yl)-9H-carbazole (6); and 9-(4′-(10-(naphthalen-1-yl)anthracen-9-yl)biphenyl-4-yl)-9H-carbazole (7) were designed and synthesized via the Suzuki cross-coupling reaction. To explore the electroluminescent properties of these materials, multilayer OLEDs were fabricated in the following sequence: ITO/4,4′-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (NPB) (50 nm)/blue-emitting materials (1–7) (30 nm) /4,7-diphenyl-1,10-phenanthroline (Bphen) (30 nm)/lithium quinolate (Liq) (2 nm)/Al (100 nm). Among those, a device using 6 as an emitter exhibited a high external quantum efficiency of 3.83% (3.20% at 20 mA/cm2) with CIE coordinates of (0.152, 0.114). In order to improve EL efficiency, 1–7 were used as blue host materials for blue dopant materials 4′-[2-(2-diphenylamino-9,9-diethyl-9H-fluoren-7-yl)vinyl]-p-terphenyl (PFVtPh) and 3-(N-phenylcarbazol)vinyl-p-terphenyl (PCVtPh). Using 1 as a host material for blue dopant material PFVtPh, the resultant device showed high EL efficiencies with 10.35 cd/A, 8.77 lm/W, and 5.70% (10.24 cd/A, 6.06 lm/W, and 5.66% at 20 mA/cm2). Furthermore, using 4 as a host for the PCVtPh blue dopant, device 4c exhibited efficient deep-blue emissions with a maximum external quantum efficiency of 2.96% and CIE coordinates of (0.154, 0.087), very close to the NTSC blue standard of (0.14, 0.08).
Co-reporter:Ji Hoon Seo, Kum Hee Lee, Bo Min Seo, Ja Ryong Koo, Se Jin Moon, Jung Keun Park, Seung Soo Yoon, Young Kwan Kim
Organic Electronics 2010 Volume 11(Issue 10) pp:1605-1612
Publication Date(Web):October 2010
DOI:10.1016/j.orgel.2010.07.012
High-efficiency deep-blue organic light-emitting diodes (OLED) using novel deep-blue host and dopant based on dual-emitting layer (D-EML) system which compose of 2-methyl-9,10-di(2-naphthyl)anthracene and 4′-(dinaphthalen-2-yl)-1,1′-binaphthyl as hosts and 9-N-phenylcarbazole-3-vinyl-p-terphenyl as a dopant exhibits good confinement of holes and electrons and broad recombination zone. The optimized deep-blue OLED showed a maximum luminance of 5780 cd/m2 at 10.5 V, maximum external quantum efficiency of 4.68%, a maximum current efficiency of 5.22 cd/A, and Commission Internationale d’Eclairage coordinates of (0.15, 0.09). This deep-blue OLED with D-EML also showed higher efficiency by a factor of 1.4 and 1.3 at 1 mA/cm2 than the control devices with single-EML using MADN and DNBN, respectively.
Co-reporter:Seul Ong Kim, Kum Hee Lee, Gu Young Kim, Ji Hoon Seo, Young Kwan Kim, Seung Soo Yoon
Synthetic Metals 2010 Volume 160(11–12) pp:1259-1265
Publication Date(Web):June 2010
DOI:10.1016/j.synthmet.2010.03.020
We have designed and synthesized five blue emitters based on diphenylaminofluorenylstyrene emitting core groups. Multilayered OLEDs were fabricated using these materials as dopants in a 2-methyl-9,10-di(naphthen-2-yl)anthracene (MADN) host. One of them in particular a deep blue OLED using dopant 9-[4-(2-diphenylamino-9,9-diethylfluoren-7-yl)phenyl]-9-phenylfluorene (3) at 15% doping concentration exhibited a maximum luminance of 4720 cd m−2 at 9.0 V, a luminous efficiency of 5.3 cd A−1 at 20 mA cm−2, a power efficiency of 2.9 lm W−1 at 20 mA cm−2, an external quantum efficiency of 4.8% at 20 mA cm−2, and CIE coordinates (x = 0.15, y = 0.13) at 8.0 V. Furthermore, this deep blue device had very stable CIE coordinates of (x = 0.15, y = 0.13) that did not vary with doping concentration from 5% to 15%.
Co-reporter:Kum Hee Lee, Woochul Lee, Min Kyu Kim, Ji Hyun Seo, Young Kwan Kim, Seung Soo Yoon
Thin Solid Films 2010 Volume 518(Issue 14) pp:3972-3977
Publication Date(Web):3 May 2010
DOI:10.1016/j.tsf.2009.11.019
A series of cyclometalated iridium complexes with 2-fluorenylquinoline derivative ligands were synthesized and their photophysical and electroluminescent properties examined using multilayered, organic light-emitting diodes fabricated with the complexes as dopant materials. In the device containing the complex 3 dopant, the maximum luminance was 20,200 cd/m2 at 14 V, the luminous and power efficiencies were 14.1 cd/A and 11.0 lm/W, respectively, and the CIE coordinates were (0.65, 0.35) which were close to saturated red emission.
Co-reporter:Kum Hee Lee, Jae Nam You, Sunwoo Kang, Jun Young Lee, Hyuk Joo Kwon, Young Kwan Kim, Seung Soo Yoon
Thin Solid Films 2010 Volume 518(Issue 22) pp:6253-6258
Publication Date(Web):1 September 2010
DOI:10.1016/j.tsf.2010.03.144
A new series of blue fluorescent emitters based on t-butylated bis(diarylaminoaryl) anthracenes were synthesized and their electroluminescent properties investigated. Into these blue materials, t-butyl groups were introduced to both prevent molecular aggregation between the blue emitters through steric hindrance and reduce self-quenching. As such, this would contribute to overall improvement in OLED efficiency. To explore the electroluminescent properties of these materials, multilayered OLEDs were fabricated into a device structure of: ITO/NPB(50 nm)/blue emitters doped in ADN(30 nm)/Alq3(20 nm)/Liq(2 nm)/Al(100 nm). All devices showed efficient blue emissions. In particular, one device exhibited highly efficient sky blue emissions with a maximum luminance of 11,060 cd/m2 at 12.0 V and respective luminous and power efficiencies of 6.59 cd/A and 2.58 lm/W at 20 mA/cm2. The peak wavelength of the electroluminescence was 468 nm with CIEx,y coordinates of (0.159, 0.198) at 12.0 V. In addition, a deep blue device with CIEx,y coordinates of (0.159, 0.151) at 12.0 V showed a luminous efficiency of 4.2 cd/A and power efficiency of 1.66 lm/W at 20 mA/cm2.
Co-reporter:Bo Min Seo, Ji Hoon Seo, Jun Ho Kim, Jung Sun Park, Kum Hee Lee, Min Hye Park, Seung Soo Yoon, Young Kwan Kim
Thin Solid Films 2010 Volume 518(Issue 22) pp:6214-6218
Publication Date(Web):1 September 2010
DOI:10.1016/j.tsf.2010.03.172
The authors have demonstrated efficient orange-red organic lighting diodes (OLEDs) using a new fluorescent orange-red material, 9,10-bis[4-(di-4-tert-buthylphenylamino)styryl]anthracene (ATBTPA). The optimized orange-red OLED using ATBTPA achieved a maximum external quantum efficiency (EQE) of 3.78%, a current efficiency (CE) of 9.47 cd/A, and Commision Internationale de L'Eclairage (CIEx,y) coordinates of (0.51, and 0.48) at 1.61 mA/cm2 in comparison with orange-red OLED using (5,6,11,12)-tetraphenyl-naphthacene (rubrene) which showed a maximum EQE of 1.65%, CE of 4.94 cd/A, and CIEx,y coordinates of (0.50, and 0.49) at 0.61 mA/cm2, respectively. The optimized orange-red device using ATBTPA showed higher efficiency of two times the orange-red device using rubrene due to the efficient Förster singlet energy transfer from MADN to ATBTPA in comparison with that from MADN to rubrene. This study clearly suggests that ATBTPA is an excellent fluorescent orange-red material for efficient WOLEDs.
Co-reporter:Kum Hee Lee, Hyun Ju Kang, Jeong Keun Park, Ji Hyun Seo, Young Kwan Kim, Seung Soo Yoon
Thin Solid Films 2010 Volume 518(Issue 22) pp:6188-6194
Publication Date(Web):1 September 2010
DOI:10.1016/j.tsf.2010.03.146
A series of red-phosphorescent iridium (III) complexes 1–4 based on 5-benzoyl-2-phenylpyridine derivatives was synthesized. Their photophysical and electrophosphorescent properties were investigated. Multilayered OLEDs were fabricated with a device structure ITO/4,4′,4″-tris(N-(naphtalen-2-yl)-N-phenyl-amino)triphenylamine (60 nm)/4,4′-bis(N-naphtylphenylamino)biphenyl (20 nm)/Ir(III) complexes (8%) doped in 4,4′-N,N′-dicarbazolebiphenyl (30 nm)/2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (10 nm)/tris(8-hydroxyquinolinyl)aluminum(III) (20 nm)/Liq (2 nm)/Al (100 nm). All devices exhibited efficient red emissions. Among those, in a device containing iridium complex 1 dopant, the maximum luminance was 14200 cd/m2 at 14.0 V. Also, its luminous, power, and quantum efficiency were 10.40 cd/A, 3.44 lm/W and 9.21% at 20 mA/cm2, respectively. The peak wavelength of the electroluminescence was 607 nm, with CIE coordinates of (0.615, 0.383) at 12.0 V, and the device also showed a stable color chromaticity with various voltages.
Co-reporter:Seok Jae Lee, Ji Hoon Seo, Jun Ho Kim, Hoe Min Kim, Kum Hee Lee, Seung Soo Yoon, Young Kwan Kim
Thin Solid Films 2010 Volume 518(Issue 22) pp:6184-6187
Publication Date(Web):1 September 2010
DOI:10.1016/j.tsf.2010.04.049
We demonstrated efficient white electrophosphorescence with a heavily doped phosphorescent blue emitter and a triplet exciton blocking layer (TEBL) inserted between the hole transporting layer (HTL) and the emitting layer (EML). We fabricated white organic light-emitting diodes (WOLEDs) (devices A, B, C, and D) using a phosphorescent red emitter; bis(2-phenylquinolinato)-acetylacetonate iridium III (Ir(pq)2acac) doped in the host material; N,N′-dicarbazolyl-3,5-benzene (mCP) as the red EML and the phosphorescent blue emitter; bis(3,5-Difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III (FIrpic) doped in the host material; p-bis(triphenylsilyly)benzene (UGH2) as the blue EML. The properties of device B, which demonstrate a maximum luminous efficiency and external quantum efficiency of 26.83 cd/A and 14.0%, respectively, were found to be superior to the other WOLED devices. It also showed white emission with CIEx,y coordinates of (x = 0.35, y = 0.35) at 8 V. Device D, which has a layer of P-type 4,4′,4″-tri(N-carbazolyl)triphenylamine (TCTA) material between the HTL and TEBL, was compared with device A to determine the 430 nm emission peak.
Co-reporter:Kum Hee Lee, Lee Kyung Kang, Young Soo Kwon, Jin Yong Lee, Sunwoo Kang, Gu Young Kim, Ji Hoon Seo, Young Kwan Kim, Seung Soo Yoon
Thin Solid Films 2010 Volume 518(Issue 18) pp:5091-5097
Publication Date(Web):1 July 2010
DOI:10.1016/j.tsf.2010.02.063
A series of blue fluorescent 9,9-diethyl-2,7-distyryl-9H-fluorene derivatives with various capping moieties such as diphenylamino; diphenylphosphino; triphenylsilyl; phenoxy; phenylmercapto; phenylselenoxy; and triphenymethyl groups were synthesized using the Honor–Emmons reaction. The highest occupied molecular orbital-lowest unoccupied molecular orbital energy levels were characterized with a photoelectron spectrometer and rationalized with quantum mechanical density functional theory calculations. The electroluminescent properties were explored through the fabrication of multilayer devices with a structure of Indium-tin-oxide/N,N′-diphenyl-N,N′-(1-napthyl)-(1,1′-phenyl)-4,4′-diamine/2-methyl-9,10-di(2-naphthyl)anthracene:blue dopants (5–15 wt.%)/4,7-diphenyl-1,10-phenanthroline/lithium quinolate/Al. All devices, except that using NPh2, exhibited a Commission Internationale de I'Eclairage (CIE) y value less than 0.19. The best luminous efficiency of 3.87 cd/A and external quantum efficiency of 2.65% at 20 mA/cm2 were obtained in a device comprising the 4-phenylsulfanyl capped 9,9-diethyl-2,7-distyrylfluorene derivative with CIE coordinates (0.16, 0.18).
Co-reporter:Kum Hee Lee, Young Soo Kwon, Lee Kyung Kang, Gu Young Kim, Ji Hoon Seo, Young Kwan Kim, Seung Soo Yoon
Synthetic Metals 2009 Volume 159(23–24) pp:2603-2608
Publication Date(Web):December 2009
DOI:10.1016/j.synthmet.2009.09.018
A series of diphenylaminofluorene- and phenylcarbazole-derived, blue fluorescent molecules have been synthesized via the Hornor–Wadsworth–Emmons and Suzuki-cross coupling reactions. To explore the electroluminescent properties of these molecules, multilayer devices were fabricated with a structure of ITO/NPB/(1–6) doped in MADN/Bphen/Liq/Al, yielding a device that exhibited highly efficient sky-blue emissions with the luminous efficiency of 11.2 cd/A at 20 mA/cm2, a power efficiency of 7.35 lm/W at 20 mA/cm2, and CIEx,y coordinates of (x = 0.16, y = 0.26) at 8 V. Also, a deep blue OLED with CIEx,y coordinates of (x = 0.16, y = 0.13) at 8 V showed a luminous efficiency of 2.13 cd/A and power efficiency of 1.20 lm/W at 20 mA/cm2, respectively.
Co-reporter:Kum Hee Lee, Seul Ong Kim, Jae Nam You, Sunwoo Kang, Jin Yong Lee, Kyoung Soo Yook, Soon Ok Jeon, Jun Yeob Lee and Seung Soo Yoon
Journal of Materials Chemistry A 2012 - vol. 22(Issue 11) pp:NaN5154-5154
Publication Date(Web):2012/02/03
DOI:10.1039/C2JM14869B
A series of tert-butylated spirofluorene derivatives incorporating a diphenylaminoaryl-vinyl group was synthesized via the Horner–Wadsworth–Emmons olefination and a Suzuki cross-coupling reaction. To examine the electroluminescent properties of these materials, multilayered OLEDs were fabricated into the following device structure: ITO/DNTPD/NPB/MADN:blue dopant materials 1–14/Alq3/Liq/Al. All devices showed efficient blue emission. In particular, one device exhibited highly efficient sky blue emission with a maximum luminance of 25100 cd m−2 at 8.5 V, as well as luminous, power and external quantum efficiencies of 9.5 cd A−1, 5.1 lm W−1 and 6.7% at 20 mA cm−2, respectively. The peak wavelength of electroluminescence was 458 and 484 nm with CIEx,y coordinates of (0.14, 0.21) at 8.0 V. In addition, a deep blue device with CIEx,y coordinates of (0.15, 0.15) at 8.0 V showed a luminous efficiency and external quantum efficiency of 3.8 cd A−1 and 3.3% at 20 mA cm−2, respectively.
Co-reporter:Kum Hee Lee, Jeong Keun Park, Ji Hoon Seo, Se Won Park, Young Sik Kim, Young Kwan Kim and Seung Soo Yoon
Journal of Materials Chemistry A 2011 - vol. 21(Issue 35) pp:NaN13648-13648
Publication Date(Web):2011/08/08
DOI:10.1039/C1JM12097B
A series of anthracene derivatives with a triphenylsilane end-capping group, (9,9-dimethyl-2-(10-phenylanthracen-9-yl)-9H-fluoren-7-yl)triphenylsilane (PAFTPS), 9,10-bis(9,9-dimethyl-2-(triphenylsilyl)-9H-fluoren-7-yl)anthracene (BFPSA), (9,9-dimethyl-2-(9,10-diphenylanthracen-2-yl)-9H-fluoren-7-yl)triphenylsilane (DPA-2FTPS), and (9,10-eiphenylanthracen-2-yl)triphenylsilane (DPA-2TPS), have been designed, synthesized, and characterized. A device incorporating PAFTPS as the emissive layer exhibited a high external quantum efficiency of 2.02% at 20 mA cm−2 with color coordinates of (0.152, 0.072) as a non-doped blue emitter. At even higher efficiency, an external quantum efficiency up to 2.32% at 20 mA cm−2 with color coordinates of (0.155, 0.076) was obtained when doped with the blue fluorescent material, 3-(N-phenylcarbazol)vinyl-p-terphenyl (PCVtPh). Furthermore, an efficient white OLED with an external quantum efficiency, a luminous efficiency and color coordinates of 4.18%, 9.14 cd A−1 at 1000 cd m−2 and (0.43, 0.41) at 1000 cd m−2 was demonstrated by exploiting this highly efficient blue fluorescent material (PAFTPS) as a host in the blue emitting layer.
![4,4,5,5-Tetramethyl-2-[4-(10-phenylanthracen-9-yl)phenyl]-1,3,2-dioxaborolane](http://img.cochemist.com/ccimg/1143600/1143576-84-4.png)
![4,4,5,5-Tetramethyl-2-[4-(10-phenylanthracen-9-yl)phenyl]-1,3,2-dioxaborolane](http://img.cochemist.com/ccimg/1143600/1143576-84-4_b.png)
![1H-Benzimidazole, 2-[4-(9,10-di-2-naphthalenyl-2-anthracenyl)phenyl]-1-phenyl-](/data/chemimg/97900/561064-11-7.png)
![1H-Benzimidazole, 2-[4-(9,10-di-2-naphthalenyl-2-anthracenyl)phenyl]-1-phenyl-](/data/chemimg/97900/561064-11-7_b.png)
![4-[(7-CHLORO-2-METHOXY-1,5-DIHYDROBENZO[B][1,5]NAPHTHYRIDIN-10-YL)IMINO]-2,6-BIS(PYRROLIDIN-1-YLMETHYL)CYCLOHEXA-2,5-DIEN-1-ONE](http://img.cochemist.com/ccimg/74900/74847-35-1.png)
![4-[(7-CHLORO-2-METHOXY-1,5-DIHYDROBENZO[B][1,5]NAPHTHYRIDIN-10-YL)IMINO]-2,6-BIS(PYRROLIDIN-1-YLMETHYL)CYCLOHEXA-2,5-DIEN-1-ONE](http://img.cochemist.com/ccimg/74900/74847-35-1_b.png)
![1,2,3,5,6,7-Hexahydropyrido[3,2,1-ij]quinoline-9-carbaldehyde](http://img.cochemist.com/ccimg/34000/33985-71-6.png)
![1,2,3,5,6,7-Hexahydropyrido[3,2,1-ij]quinoline-9-carbaldehyde](http://img.cochemist.com/ccimg/34000/33985-71-6_b.png)
![7,10-Dichloro-2-methoxybenzo[b]-1,5-naphthyridine](http://img.cochemist.com/ccimg/6700/6626-40-0.png)
![7,10-Dichloro-2-methoxybenzo[b]-1,5-naphthyridine](http://img.cochemist.com/ccimg/6700/6626-40-0_b.png)
![Benzoic acid,4-chloro-2-[(6-methoxy-3-pyridinyl)amino]-](http://img.cochemist.com/ccimg/6700/6626-07-9.png)
![Benzoic acid,4-chloro-2-[(6-methoxy-3-pyridinyl)amino]-](http://img.cochemist.com/ccimg/6700/6626-07-9_b.png)
![8H-Cyclopent[a]acenaphthylen-8-one,7,9-diphenyl-](http://img.cochemist.com/ccimg/700/641-57-6.png)
![8H-Cyclopent[a]acenaphthylen-8-one,7,9-diphenyl-](http://img.cochemist.com/ccimg/700/641-57-6_b.png)
![5H-Pyrido[3,2-b]indole](http://img.cochemist.com/ccimg/300/245-08-9.png)
![5H-Pyrido[3,2-b]indole](http://img.cochemist.com/ccimg/300/245-08-9_b.png)
![Boronic acid, B-[10-(1-naphthalenyl)-9-anthracenyl]-](/data/chemimg/38000/400607-46-7.png)
![Boronic acid, B-[10-(1-naphthalenyl)-9-anthracenyl]-](/data/chemimg/38000/400607-46-7_b.png)
![1,4-Benzenediamine, N1-2-naphthalenyl-N4,N4-bis[4-(2-naphthalenylphenylamino)phenyl]-N1-phenyl-](/data/chemimg/104700/185690-41-9.png)
![1,4-Benzenediamine, N1-2-naphthalenyl-N4,N4-bis[4-(2-naphthalenylphenylamino)phenyl]-N1-phenyl-](/data/chemimg/104700/185690-41-9_b.png)
![[1,1'-Biphenyl]-4,4'-diamine, N4,N4'-di-2-naphthalenyl-N4,N4'-diphenyl-](/data/chemimg/108300/139255-17-7.png)
![[1,1'-Biphenyl]-4,4'-diamine, N4,N4'-di-2-naphthalenyl-N4,N4'-diphenyl-](/data/chemimg/108300/139255-17-7_b.png)
