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To develop the efficient blue phosphorescent host materials for Organic light-emitting Diodes (OLEDs), cyanocarbazole-substituted 3',5'-di(9H-carbazol-9-yl)-1,1'-biphenyl derivatives are designed and synthesized. Multilayer devices were fabricated in the following sequence; ITO (180 nm)/Tris(4-carbazoyl-9-ylphenyl)amine (TCTA) (75 nm)/Blue phosphorescent host materials (15 nm)/Bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III) (Firpic) (15 nm)/1,3,5-Tri(m-pyridine-3-ylphenyl)benzene (TmPyPB) (40 nm)/Liq (2 nm)/Al (100 nm). In particularly, blue phosphorescent device using 9-(3',5'-di(9H-carbazol-9-yl)-[1,1'-biphenyl]-4-yl)-9H-carbazole-3-carbonitrile as a host material exhibited efficient emission with a luminous efficiency, a power efficiency, an external quantum efficiency, and CIE coordinates of 11.6 cd/A, 4.10 lm/W, 5.62% at 20 mA/cm2, and (0.15, 0.33) at 8 V, respectively. [ABSTRACT FROM AUTHOR]

We designed and synthesized biindenophenanthrene derivatives for blue fluorescent organic light-emitting diodes (OLEDs) materials to overcome the disadvantages of blue emitter caused by the wide band gap. To demonstrate the electroluminescence (EL) properties, the OLEDs devices were fabricated in the following sequence: indium-tin-oxide (180 nm)/4,4',4"-tris[2-naphthyl(phenyl)amino (30 nm)/4,4'-bis(N-(1-naphthyl)-N-phenylamino) biphenyl (20 nm)/Blue emitting materials (20 nm)/Bathophenanthroline (30 nm)/lithium quinolate (2 nm)/Al (100 nm). Device A that using 13,13,13',13'-tetramethyl-13H,13'H-11,11'-biindeno[1,2-l]phenanthrene in emitting layer showed luminous efficiency, power efficiency, and external quantum efficiency of 1.72 cd/A, 0.58 lm/W, 1.03% at 20 mA/cm2 with Commission Internationale d'Énclairage (CIE) coordinates of (0.15, 0.23) at 8.0 V. [ABSTRACT FROM AUTHOR]

To develop the efficient blue emitters for Organic light-emitting diodes (OLEDs), this paper reports the synthesis and electroluminescent properties of diphenylvinylarenes end-capped with diphenylamine groups. Two OLEDs were fabricated in the following sequence: indium-tin-oxide (ITO) /N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diam-ine (NPB) (50 nm) / Blue emitters (30 nm) / bathophenanthroline (Bphen) (30 nm) / lithium quinolate (Liq) (2 nm) /Al (100 nm). Two devices exhi-bited blue electroluminescence. In particular, a device using 9,9-diethyl-N,N-diphenyl-7-(2,2-diphenylvinyl)-9H-fluoren-2-amine exhibited blue emission with a luminance efficiency, a power efficiency, an external quantum efficiency and Commission Internationale d’Énclairage (CIE) coordinates of 5.48 cd/A, 2.45 lm/W, 2.85% at 20 mA/cm² and (x = 0.17, y = 0.25) at 8.0 V, respectively. [ABSTRACT FROM AUTHOR]

A single-inductor boost light-emitting diode (LED) driver that can distribute equal dc currents to multiple channels of LEDs is presented. To ensure uniform brightness in display backlight units, the previous approaches used current regulation elements serially inserted in individual LED channels, which incur power losses. Instead, the proposed LED driver adopts a single-inductor–multiple-output boost converter topology, which keeps the channel currents equal in an open-loop fashion by connecting the current-delivering inductor to each channel for an equal period of time, in a time-division multiplexing manner. Furthermore, the sequence of conduction is continuously permutated in order to reduce possible systematic imbalances among the currents. A prototype LED driver demonstrates the peak power efficiency of 93.0% excluding the field-programmable gate array controller power and maximum current balance error of 2.04% while delivering 12.4 W to three channels of high-brightness white LEDs. [ABSTRACT FROM AUTHOR]

We have demonstrated efficient phosphorescent white organic light-emitting diodes (PHWOLEDs) by using iridium (III) bis(1-phenyl(quinolinato-N,C2′))acetylacetonate doped in 4,4,4-tris(N-carbazolyl)-triphenylamine as phosphorescent red emitting layer and iridium (III) bis[(4,6-di-fluoropheny)-pyridinato-N,C2] picolinate doped in dual blue-emitting layer (D-BEML), N,N′-dicarbazolyl-3,5-benzene and 2,2′,2″″-(1,3,5-benzenetryl) tris(1-phenyl)- 1H-benzimidazol, respectively. D-BEML structure have broad exciton formation zone than single BEML. The optimized PHWOLEDs showed an external quantum efficiency of 5.93%, current efficiency of 11.54 cd/A, and Commission Internationale de L’Eclairage coordinates of (0.45, 0.37) at 1000 cd/m2. [ABSTRACT FROM PUBLISHER]

This paper reports the synthesis and electroluminescent properties of new red fluorescent materials, 4-(dicyanomethylene)-2-(1,1-dimethyl-7-trimethylsiliyl methyl-julolidyl-9-enyl)-6-(4-pentylbicyclo[2.2.2]octan-1-yl)-4H-pyran (DCJTMS) and 4-(dicyanomethylene)-2-(1,7-bistrimethylsiliylmethyl-julolidyl-9-enyl)-6-(4-pentylbicyclo[2.2.2]octan-1-yl)-4H-pyran (DCJDTMS). In these red emitters, the bulky groups such as trimethylsilane and n-pentyl-bicyclo[2,2,2]octane were introduced into and 4-(dicyanomethylene)-2-methyl-6-[p-(dimethylamino)-styryl]-4H-pyran (DCM) skeleton to increase the steric hindrance between the red emitters and prevent concentration quenching. An OLED device using 4-(dicyanomethylene)-2-(1,7-bis(trimethylsiliylmethyl)-julolidyl-9-enyl)-6-(4-pentylbicyclo[2.2.2]octan-1-yl)-4H-pyran (DCJDTMS) as a dopant exhibited the efficient red emission with a Luminous efficiency, Power efficiency and Commision Internationale De L’Eclairage (CIEx,y) coordinates of 3.66 cd/A, 2.13 lm/W at 20 mA/cm2 and (0.62, 0.38) at 7.0 V, respectively. Compared to device using 4-(dicyanomethylene)-2-(1,1,7,7-tetra-methyljulolidyl-9-enyl)-6-tert-butyl-4H-pyran (DCJTB), the red device using DCJDTMS showed the greatly improved EL efficiency due to the more bulky substituents of compound DCJDTMS. [ABSTRACT FROM PUBLISHER]

In this study, we synthesized new 2-(2-(4-(diphenylamino)styryl)-4H-chromen-4-ylidene) malononitrile (DCCPA) derivatives with different π-conjugation aromatic spacer groups between the diphenylamine and (chromen-4-ylidene)malononitrile moieties of the DCCPA. To explore the electroluminescence properties of these materials, multilayered OLEDs were fabricated with a device stricture of: Indium Tin Oxide (ITO) (170 nm)/N,N’-diphenyl-N,N’-(1-napthyl)-(1,1’-phenyl)-4,4’-diamine (NPB) (50 nm)/2-methyl-9,10-bis-2-naphthyl anthracene (MADN):Red dopants 1 (5, 10%) (30 nm)/bis-(2-methyl-8-quinolinolato-N1,O8)-(1,1’-biphenyl-4-olato)aluminum (Balq) (30 nm)/Liq (2 nm)/Al (10 nm). A device using Red 1 showed a maximum luminance of 1030 cd/m2 at 10.0 V, with maximum luminous, power, and quantum efficiencies of 0.94 cd/A, 0.54 lm/W, and 1.11%, respectively. The CIE coordinates of this device were (0.61, 0.35) at 7.0 V, a stable color chromaticity at various voltages. [ABSTRACT FROM PUBLISHER]

We designed and synthesized new red fluorescent materials based on t-butylated 2-(2-(4-(diarylamino)styryl)-4H-chromen-4-ylidene)malononitrile derivatives (3a-3d). A device using 2-(6,8-di-tert-butyl-2-(4-((4-tert-butylphenyl)(2,7-di-tert-butyl-9,9-diethyl-9H-fluoren-4-yl)amino)styryl)-4H-chromen-4-ylidene)malononitrile (3a) as a dopant showed efficient red electroluminescent properties with a maximum luminance of 3357 cd/m2 at 15.0 V, and maximum luminous and power efficiencies of 1.12 cd/A and 0.60 lm/W, respectively. The CIE coordinates of this device using this material was (0.64, 0.35) at 7.0 V, and this device also showed stable color chromaticity at various voltages. [ABSTRACT FROM PUBLISHER]

The authors have demonstrated red organic light-emitting diodes (OLEDs) using a new fluorescent red emitter, 2-(2-(4-pentylbicyclo[2.2.2]octan-1-yl)-6-(2-(1,1,7-trimethyl-7-triphenysiliyllethyl-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)vinyl)-4H-pyran-4-ylidene)malononitrile (DCJTPSO), achieved the maximum external quantum efficiency (EQE) of 2.06%, current efficiency (CE) of 3.83 cd/A, and Commision Internationale De L’Eclairage (CIEx,y) coordinates of (0.58, 0.40) at 0.029 mA/cm2 in comparison with control device using 4-(dicyanomethylene)-2-tert-butyl- 6-(1,1,7, 7-tetramethyljulolidin-4-yl-vinyl)- 4H-pyran which showed the maximum EQE of 1.07%, CE of 1.41 cd/A and CIEx,y coordinates of (0.61, 0.38) at 0.11 mA/cm2. This result showed that the high performance of red device using DCJTPSO showed easier electron trapping directly on the emitter molecule. [ABSTRACT FROM PUBLISHER]

The photophysical characteristics of (Actpy)2Ir(acac) and (Acpsf)2Ir(acac) were investigated to determine their suitability as candidates for red light-emitting materials for organic light emitting diodes (OLEDs) [where Actpy = 3-acetyl-6-(4-tert-butylphenyl)pyridine, acac = acetoylacetonate, and Acpsf = 3-acetyl-6-(9,9’-spirobi[fluorene]-2-yl)pyridine]. To explore the electroluminescent properties of these materials, multilayered OLEDs were fabricated the device structure of ITO/NPB/CBP: 8% Ir(III) complexes/BCP/Alq3/Liq/Al. Particularly, device 1 using complex (Actpy)2Ir(acac) as a dopant material furnished a maximum luminance of 41,800 cdm−2 at 15 V, and luminous efficiency and power efficiency of 5.70 cdA−1 and 2.70 lmW−1 at 20 mAcm−2, respectively. Additionally, this device showed orange–red emission with CIE coordinates of (0.57, 0.42) at 10.0 V. [ABSTRACT FROM AUTHOR]

We have demonstrated efficient deep-blue organic light emitting diodes using 4,4'-bis(9-ethyl-3-carbazovinylene)-1,1'-biphenyl (BCzVBi) doped in 4'-(dinaphthalen-2-yl)-1,1'-binaphthyl (DNBN) as emitting layer. There is more overlap between the photoluminescence (PL) spectrum of DNBN and ultra violet (UV)/visible absorption spectrum of BCzVBi than PL spectrum of 2-methyl-9,10-di(2-naphthyl) anthracene (MADN) and UV/visible absorption of BCzVBi, resulting in efficient energy transfer from DNBN to BCzVBi. The optimized deep-blue device showed a peak current efficiency of 5.12 cd/A, peak external quantum efficiency (EQE) of 4.72%, and as Commission Internationale d'Eclairage coordinates of (0.15, 0.12). The device using blue host, DNBN, exhibited higher EQE of 1.6 times at 1 mA/cm2 than control device using blue host, MADN. [ABSTRACT FROM AUTHOR]

We fabricated the organic light-emitting diodes (OLEDs) with sensitizer by solution process. The addition of sensitizer into the emission layer improved the device efficiency. 4,4'-N,N'-dicarbazole-biphenyl (CBP), bis(2-phenylquinoline)iridium(III) (acetylacetonate) [Ir(pq)2(acac)], tris(2-phenylpyridine)iridium [Ir(ppy)3] were used as host, red emitting dopant, and sensitizer, respectively. The sensitizer leads to the cascade energy transfer from the host into the red emitting dopant. The doping concentration of sensitizer was varied as 0∼20 wt% and optimized. As a result, the device with 5% Ir(ppy)3 shows the luminous efficiency, power efficiency, and quantum efficiency of 5.1 cd/A, 4.0 lm/W, and 3.0%, respectively. These efficiencies are about 3 times as high as that of device without sensitizer. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate development of red phosphorescent Organic Light-Emitting Diodes (OLEDs) as the doping concentrations are varied with lithium-quinolate (Liq) doped electron transport layer (ETL). The experimental device has both mixed electron transport layer and electron injection layer. The device configuration was ITO/NPB (50 nm)/4,4'-N-N'-dicarbazole-biphenyl (CBP) doped with 8% bis(2-phenylquinoline)iridium(III) (acetylacetonate) [Ir(pq)2(acac)] (30 nm)/Bphen doped with X% Liq (30 nm)/Liq (2 nm)/Al (100 nm), where the doping concentration of Liq in ETL was varied as 5%∼65%. When the Liq was mixed in the ETL, the efficiency and operating voltage of the experimental devices were improved in comparison with the reference device due to greater electron transport efficiency and an improved hole-electron balance. [ABSTRACT FROM AUTHOR]

In this paper, We have demonstrated lower driving voltage and efficient Blue phosphorescent organic light emitting diodes (PHOLEDs) using iridium (III) bis[(4,6-di-fluoropheny)-pyridinato-N,C2] picolinate doped in N,N'-dicarbazolyl-3,5-benzene (mCP) and 2,2',2''-(1,3,5-benzenetryl)tris(1-phenyl)-1H-benzimidazol (TPBi) as double-emitting layer system. D-EML layers were employed to have good exciton confinement. We also demonstrated that mCP as electron blocking layer inserted EML and HTL for higher efficiency. The optimized device of double EML of mCP:TPBi(1:1) exhibited a maximum external quantum efficiency of 9.22% at 0.21 mA/cm2, a maximum Current efficiency of 18.89 cd/A at 0.21 mA/cm2, and Commission Internationale de I'Eclairage coordinates of (0.17, 0.35) at 1000 cd/m2, respectively. [ABSTRACT FROM AUTHOR]

We compared the electrical characteristics of polymer, poly(N-vinylcarbazole) (PVK) and small molecule, 4,4'-N,N'-dicarbazole-biphenyl (CBP), N,N'-dicarbazolyl-3,5-benzene (mCP), as host material in white organic light-emitting diodes (OLEDs) fabricated by solution process. In order to obtain the white emission, iridium(III) bis(4,6-difluorophenylpyridinato)-picolinate) (Firpic) and iridium(III) bis(2-phenylquinoline)(acetylaceton) [Ir(pq)2acac] were used as blue and red emitting dopant, respectively. As a result, devices with PVK, CBP, and mCP have the max. luminous efficiencies of 10.5 cd/A, 9.8 cd/A, and 4.2 cd/A, respectively. [ABSTRACT FROM AUTHOR]

The naphthalene-based blue materials 4,4'-(Dinaphthalen-2-yl)-1,1'-binaphthyl (DNBN) and 1,4-(Dinaphthalen-2-yl)-naphthalene (DNN) were designed and synthesized for OLEDs. A device (non-doped) employing DNN as the emitter exhibited a maximum luminance, luminous efficiency, and external quantum efficiency of 1120 cd/m2, 1.40 cd/A, and 3.83%, respectively. Moreover, its CIE coordinates (0.152, 0.069) are very close to the NTSC blue standard of (0.14, 0.08). In order to improve EL efficiencies, these materials were used as the blue host materials for the blue dopants PFVtPh and PCVtPh. A device 1b (PFVtPh-doped) showed high EL efficiencies of 5.24 cd/A, 2.75 lm/W, and 3.82% at 20 mA/cm2. [ABSTRACT FROM AUTHOR]

New electroluminescent materials, 4,4'-bis(2-naphthyl-4-tert-butylphenylamino)stilbene (1), 4,4'-bis(4-tert-butylphenyl-3,5-di-tert-butylphenylamino)stilbene (2), and 4,4'-bis(di-4-tert-butylphenylamino)stilbene (3) were synthesized and characterized. To evaluate the electroluminescent properties of these compounds, multilayered OLED devices 1-3 were designed. By employing blue dopant 1 into a multilayer device, it was possible to achieve a maximum luminance of 8861 cd m-2 at 12.0 V, a luminous efficiency of 6.82 cd A-1 at 20 mA cm-2, a power efficiency of 2.72 lm W-1 at 20 mA cm-2, and CIEx,y coordinates of (x = 0.158,y = 0.187) at 10.0 V. These results demonstrated the superiority of these bis(diarylamino)stilbene derivatives in organic light-emitting devices. [ABSTRACT FROM AUTHOR]

A series of red-phosphorescent Ir(III) complexes based on 5-benzoyl-2-phenylpyridine derivatives were synthesized. To explore their electroluminescent properties, multilayered OLEDs were fabricated the device structure of ITO/2-TNATA/NPB/Ir(III) complexes (8%) doped in CBP/BCP/Alq3/Liq/Al. The device 2 displays the excellent EL performances; its LE, PE, and EQE reach 30.4 cd/A, 10.1 lm/W, and 8.23% at 20 mA/cm2, respectively. The maximum electroluminescence spectrum peak was 571 nm, with the CIE coordinates of (0.486, 0.512) at 12.0 V, and the device also showed a stable color chromaticity with various voltages. [ABSTRACT FROM AUTHOR]

We describe the electroluminescent properties of blue fluorescent materials based on mono(triphenylamino)anthracene derivatives synthesized via Suzuki cross coupling reactions. To explore the electroluminescent properties of materials 1-3, multilayered OLEDs were fabricated and all devices exhibited efficient blue emissions. Among those, device 1, with CIE x,y coordinates of (0.159, 0.166) at 12.0 V, exhibited the best performance, with a maximum luminance of 7306 cd/m2 at 12.0 V, and luminous and power efficiencies of 4.95 cd/A and 1.83 lm/W at 20 mA/cm2, respectively. [ABSTRACT FROM AUTHOR]

We investigated the electroluminescent characteristics of three devices which were fabricated with a green phosphorescent emitter bis[2-(o-terphen-3-yl)pyridinato-C,N]iridium(III) (acetylacetonate) [(tppy)2Ir(acac)] doped in triphenylsilane-based host materials, such as 4,4'-bis(triphenylsilyl)biphenyl (BSB), 9,9'-spirobifluorene-2-yltriphenylsilane (SFS) and (4-(10-(naphthalene-2-yl)anthracen-9-yl)phenyl)triphenylsilane (ANPTPS), which have the different the triplet energy levels (ET) of 2.61 eV, 2.64 eV and <1.91 eV, respectively. Among those, two devices using BSB and SFS hosts with the suitable ET energy levels to green phosphorescent dopant exhibited the highly efficient green electrophosphorescence with the maximum luminous efficiencies of 51.3 cd/A and 46.6 cd/A, respectively, and the maximum quantum efficiencies of 13.9% and 12.4%, respectively. [ABSTRACT FROM AUTHOR]

The authors have demonstrated highly efficient white organic light-emitting diodes (WOLEDs) by using two emissive materials as a dopant, 1,4-bis[2-(7-N-diphenyamino-2-(9,9-diethyl-9H-fluoren-2-yl)) vinyl] benzene (DAF-ph) and iridium(III) bis(5-acetyl-2-phenylpyridinato-N,C2′) acetylacetonate ((acppy)2Ir(acac)). It was found that the OLED fabricated in this study emitted a white color consisting of three primary colors (red, green, and blue). The luminance-voltage (L-V) characteristics of the WOLEDs showed the maximum luminance of 30 500 cd/m2 at 14 V and the maximum luminous efficiency of 38.0 cd/A, respectively. The CIEx,y coordinates of the WOLED also showed (x=0.33, y=0.40) at 10 V. [ABSTRACT FROM AUTHOR]

In this study, white organic light-emitting diodes (WOLEDs) based on exciplexes with a simple structure were investigated. Several combinations of hole-transport material and electron-transport material (ETM) were examined to verify the formation of the exciplexes. Various combinations of these exciplexes contributed to the blue and green emitters, as well as the host within the WOLEDs. Four types of WOLEDs were fabricated using various ETMs 2,2′,2′′-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi), 4,7-diphenyl-1,10-phenanthroline (BPhen), bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum (BAlq), and 2,6-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (26DCzppy) within the emitting layers (EMLs). In this work, which comprised a blue EML with a 1:1 wt ratio of tris(4-carbazoyl-9-ylphenyl)amine (TCTA) and TPBi, a green EML prepared by mixing 4,4′,4″-tris[phenyl( m -tolyl)amino]triphenylamine ( m -MTDATA) and ETMs at a weight ratio of 1:1, and a red EML. In addition, the exciplex formation was optimized according to the mixing concentration of the green EML when BPhen and TPBi were used as the ETM. As a result, a green EML was obtained at 50 wt% TPBi with improved performance, such as an increased power efficiency and a low efficiency roll-off in the range of 200–1000 cd/m 2 in WOLEDs. It also showed white emission for Commission Internationale de l’Éclairage coordinates of (0.45, 0.45) at 1000 cd/m 2 . [ABSTRACT FROM AUTHOR]

Four 9,9-diethyl- N , N -diphenyl-9 H -fluoren-2-amine substituted anthracene derivatives have been designed and synthesized by Suzuki cross coupling reactions. To explore the electroluminescent properties of these blue materials, multilayer blue organic light-emitting diodes were fabricated in the following device structure: indium tin oxide (180 nm)/ N , N ’-diphenyl- N , N ’-(1-napthyl)-(1,1′-phenyl)-4,4′-diamine (50 nm)/blue emitting materials ( 1 – 4 ) (30 nm)/bathophenanthroline (30 nm)/lithium quinolate (2 nm)/Al (100 nm). All devices appeared excellent deep-blue emissions. Among them, a device exhibited a maximum luminance of 5686 cd/m 2 , the luminous, power and external quantum efficiencies of 5.11 cd/A, 3.79 lm/W, and 4.06% with the Commission International de L'Eclairage coordinates of (0.15, 0.15) at 500 cd/m 2 , respectively. [ABSTRACT FROM AUTHOR]

Two phenylanthracene-substituted fluorene derivatives, 10-(9,9′-dimethyl-2-(10-phenylanthracen-9-yl)-9 H -fluoren-7-yl)-phenylanthracene ( 1 ) and 2′,7′-di-(10-phenylanthracen-9-yl)-9,9′-spirobi[9 H -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/cm 2 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) 2 Ir(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/cm 2 and the color coordinates of (0.33, 0.36) at 14 V is demonstrated. [ABSTRACT FROM AUTHOR]

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/cm 2 , respectively, and this device showed the deep blue emission with the CIE coordinates of (0.16, 0.10) at 6.0 V. [ABSTRACT FROM AUTHOR]

Abstract: 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 6.89cd/A and 3.09lm/W at 20mA/cm2, respectively, and CIE x,y coordinates of (x =0.64,y =0.36) at 7.0V, approaching saturated red emission. [Copyright &y& Elsevier]

Abstract: 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 39,000cd/m2, 12.3cd/A, 7.45lm/W, 7.71% at 20mA/cm2 and (x =0.17, y =0.31) at 8V, respectively. In addition, a blue OLED using dopant 2 with CIE coordinates (x =0.16, y =0.18) at 8V exhibited a luminous efficiency, power efficiency and external quantum efficiency of 4.39cd/A, 2.46lm/W and 2.97% at 20mA/cm2, respectively. [Copyright &y& Elsevier]

Abstract: 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 (60nm)/NPB (30nm)/MADN: Blue dopant materials 1–5 (30nm)/Alq3 (20nm)/LiF (1.0nm)/Al (200nm). All devices showed efficient blue emission. Among those, device using compound 1 as a dopant material give the best performance with high brightness (2778cd/m2 at 8.5V) and high efficiency (4.9cd/A, 2.3lm/W, and 4.0% EQE at 20mA/cm2). The peak wavelength of electroluminescence was 473nm with CIEx,y coordinates of (0.15, 0.17) at 8.5V. A deep blue device with CIEx,y coordinates of (0.15, 0.12) at 8.5V showed a luminous efficiency of 1.8cd/A and an external quantum efficiency of 1.9% at 20mA/cm. [Copyright &y& Elsevier]

Abstract: We report the enhanced room temperature gas sensing properties of ZnO nanorods by promoting UV activation via doped Ni in ZnO. Electrodeposition was used to grow nickel-doped ZnO nanorods on flexible substrates integrated with 365nm UV LED. Nickel concentration varied from 0at.% to 10at.% in aqueous solution. An enhanced gas sensing property up to 1.61 at room temperature was measured at 6at.% Ni-doped ZnO, but showed deteriorated sensitivity due to the formation of a NiO phase at higher Ni concentration. The mechanism for improved sensing properties can be explained by the involvement of weakly bound photo-induced oxygen ions upon the exposure of acetone gas. [Copyright &y& Elsevier]

Abstract: 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 (60nm)/4,4′-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (20nm)/Ir(III) complexes doped in N,N′-dicarbazolyl-4,4′-biphenyl (30nm, 8%)/2,9-dimethyl-4,7-diphenyl-phenathroline (10nm)/tris(8-hydroxyquinoline)-aluminum (20nm)/lithium quinolate (2nm)/ Al (100nm), 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 16200cd/m2 at 14.0V, 12.20cd/A at 20mA/cm2, 4.26lm/W and 9.26% at 20mA/cm2, respectively, with Commission Internationale de l''Énclairage coordinates of (0.63, 0.37) at 12.0V. [Copyright &y& Elsevier]

Abstract: 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 575–636nm. In particular, one of the devices in this study showed a maximum luminous efficiency, maximum power efficiency, external quantum efficiency and CIE coordinates of 29.0cd/A, 6.13lm/W, 8.86% at 20mA/cm2 and (0.57, 0.43) at 10V, respectively. In addition, a deep red OLED with CIE coordinates of (0.67, 0.32) at 10V exhibited a maximum luminous efficiency, maximum power efficiency and external quantum efficiency of 5.61cd/A, 1.02lm/W and 5.35% at 20mA/cm2, respectively. [Copyright &y& Elsevier]

Abstract: The authors have demonstrated hybrid white organic light-emitting diodes (HWOLEDs) on electroluminescent characteristics for codoped spacer ratio effect using N,N′-dicarbazolyl-3,5-benzene (mCP) and 4,7-diphenyl-1,10-phenanthroline (BPhen). The optimized HWOLEDs of spacer ratio (3:1) which had proper recombination balance of holes and electrons, mCP:BPhen, showed the external quantum efficiency of 6.01%, the power efficiency of 8.12 lm/W, and Commission Internationale de I’Eclairage coordinates of (0.37, 0.41) at 1000 cd/m2. [Copyright &y& Elsevier]

Abstract: 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 39.2lm/W at very low light intensity. The optimized device also shows an EQE of 16.4% at 1000cd/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 10,000cd/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. [ABSTRACT FROM AUTHOR]

Abstract: 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 5780cd/m2 at 10.5V, maximum external quantum efficiency of 4.68%, a maximum current efficiency of 5.22cd/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 1mA/cm2 than the control devices with single-EML using MADN and DNBN, respectively. [Copyright &y& Elsevier]

Abstract: 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(50nm)/blue emitters doped in ADN(30nm)/Alq3(20nm)/Liq(2nm)/Al(100nm). All devices showed efficient blue emissions. In particular, one device exhibited highly efficient sky blue emissions with a maximum luminance of 11,060cd/m2 at 12.0V and respective luminous and power efficiencies of 6.59cd/A and 2.58lm/W at 20mA/cm2. The peak wavelength of the electroluminescence was 468nm with CIEx,y coordinates of (0.159, 0.198) at 12.0V. In addition, a deep blue device with CIEx,y coordinates of (0.159, 0.151) at 12.0V showed a luminous efficiency of 4.2cd/A and power efficiency of 1.66lm/W at 20mA/cm2. [ABSTRACT FROM AUTHOR]

Abstract: 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 9.47cd/A, and Commision Internationale de L''Eclairage (CIE x,y ) coordinates of (0.51, and 0.48) at 1.61mA/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 4.94cd/A, and CIE x,y coordinates of (0.50, and 0.49) at 0.61mA/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. [Copyright &y& Elsevier]

Abstract: 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 26.83cd/A and 14.0%, respectively, were found to be superior to the other WOLED devices. It also showed white emission with CIE x , y coordinates of (x =0.35, y =0.35) at 8V. 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 430nm emission peak. [ABSTRACT FROM AUTHOR]

Abstract: 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 (60nm)/4,4′-bis(N-naphtylphenylamino)biphenyl (20nm)/Ir(III) complexes (8%) doped in 4,4′-N,N′-dicarbazolebiphenyl (30nm)/2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (10nm)/tris(8-hydroxyquinolinyl)aluminum(III) (20nm)/Liq (2nm)/Al (100nm). All devices exhibited efficient red emissions. Among those, in a device containing iridium complex 1 dopant, the maximum luminance was 14200cd/m2 at 14.0V. Also, its luminous, power, and quantum efficiency were 10.40cd/A, 3.44lm/W and 9.21% at 20mA/cm2, respectively. The peak wavelength of the electroluminescence was 607nm, with CIE coordinates of (0.615, 0.383) at 12.0V, and the device also showed a stable color chromaticity with various voltages. [ABSTRACT FROM AUTHOR]

Abstract: 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 (5–15wt.%)/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 3.87cd/A and external quantum efficiency of 2.65% at 20mA/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). [Copyright &y& Elsevier]

Abstract: 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 4720cdm−2 at 9.0V, a luminous efficiency of 5.3cdA−1 at 20mAcm−2, a power efficiency of 2.9lmW−1 at 20mAcm−2, an external quantum efficiency of 4.8% at 20mAcm−2, and CIE coordinates (x =0.15, y =0.13) at 8.0V. 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%. [Copyright &y& Elsevier]

Abstract: 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) (50nm)/blue-emitting materials (1–7) (30nm) /4,7-diphenyl-1,10-phenanthroline (Bphen) (30nm)/lithium quinolate (Liq) (2nm)/Al (100nm). Among those, a device using 6 as an emitter exhibited a high external quantum efficiency of 3.83% (3.20% at 20mA/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 10.35cd/A, 8.77lm/W, and 5.70% (10.24cd/A, 6.06lm/W, and 5.66% at 20mA/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). [Copyright &y& Elsevier]

Abstract: 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 20,200cd/m2 at 14V, the luminous and power efficiencies were 14.1cd/A and 11.0lm/W, respectively, and the CIE coordinates were (0.65, 0.35) which were close to saturated red emission. [Copyright &y& Elsevier]

Abstract: 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 11.2cd/A at 20mA/cm2, a power efficiency of 7.35lm/W at 20mA/cm2, and CIE x,y coordinates of (x =0.16, y =0.26) at 8V. Also, a deep blue OLED with CIE x,y coordinates of (x =0.16, y =0.13) at 8V showed a luminous efficiency of 2.13cd/A and power efficiency of 1.20lm/W at 20mA/cm2, respectively. [Copyright &y& Elsevier]

Abstract: High efficiency pure white organic light-emitting diodes (WOLEDs) were developed using a highly efficient diphenylaminofluorene-based deep blue fluorescent material (DAF). A high quantum efficiency of 7.1% with color coordinates of (0.15, 0.18) were obtained from the DAF-doped blue device, which was then combined with phosphorescent red/green devices. A mixed interlayer was used to control the color coordinates and charge balance in the emitting layer of the WOLEDs. The pure white hybrid WOLEDs showed a high quantum efficiency of 12.3%. [Copyright &y& Elsevier]

Abstract: Authors have demonstrated highly efficient white organic light-emitting diodes (WOLEDs) using the same blue emitter, 1,4-bis[2-(7-N-diphenyamino-2-(9,9-diethyl-9H-fluoren-2-yl)) vinyl] benzene (DAF-ph), and the different red emitters, bis(5-isobutyryl-2-phenylpyridinato-C,N)iridium(III) (acetylacetonate) ((Ibppy)2Ir(acac)) and bis(5-acetyl-2-phenylpyridinato-C,N) iridium(III) (acetylacetonate) ((acppy)2Ir(acac)). Although the red emitters had the same highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), they showed the different electrical and optical characteristics due to the difference of stearic hindrance. Two devices showed the maximum luminance of 21,600 and 30,500cd/m2 at 14V, maximum luminous efficiency of 30.2 and 38.0cd/A at 0.004 and 0.005mA/cm2, and CIE x , y coordinates of (x=0.37, y=0.43) and (x=0.33, y=0.40) at 10V, respectively. [Copyright &y& Elsevier]

The organic light-emitting devices (OLEDs) based on fluorescence have low efficiencies due to the requirement of spin-symmetry conservation. By using the phosphorescent material, the internal quantum efficiency can reach 100%, compared to 25% in the case of the fluorescent material. Thus, the phosphorescent OLEDs have recently been extensively studied and showed higher internal quantum efficiencies than the conventional OLEDs. In this study, an orange-red electrophosphorescent devices have been fabricated with a new Ir complex, synthesized by coordinating a new electrowithdrawing lignad to (ppy)2 Iracac, as the emitting dopant. It has been investigated the electrical and optical characteristics of the devices fabricated with a structure of ITO/NPB/Ir complex doped in CBP/BCP/Alq3/Li:Al/Al. The device with the Ir complex demonstrated an efficiency of 3.53 cd/A with an initial brightness of 100 cd/m2. The CIE coordinates for devices held at a current density of 1 mA/cm2 were (0.585, 0.410). [Copyright &y& Elsevier]

Abstract: The authors have demonstrated blue organic light-emitting diodes (OLED) with efficient host-dopant energy level alignment using a total of only two organic materials, 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) and 4′-[2-(2-diphenylamino-9,9-diethyl-9H-fluoren-7-yl)vinyl]-p-terphenyl (PFVtPh). MADN, with ambipolar characteristics, has adequate band gap for junction of anode-cathode and multi-functional characteristics as hole-transporting, electron-transporting, and blue host material. PFVtPh doped in MADN had highest occupied molecular orbital and lowest unoccupied molecular orbital in comparison with 1,4-bis[2-(7-N-diphenyamino-2-(9,9-diethyl-9H-fluoren-2-yl))vinyl]benzene (DAF-ph). The optimized blue OLED fabricated in this study showed a maximum external quantum efficiency of 5.84%, a maximum power efficiency of 7.57 lm/W, and Commission Internationale de I’Eclairage coordinates of (0.15, 0.21). This result also showed 10 times higher power efficiency at 10 mA/cm2 than blue device using DAF-ph dopant with mismatch of host-dopant energy level alignment. [Copyright &y& Elsevier]