•High triplet energy hole transport material derived from ortho- linked terphenyl.•Low driving voltage and high hole mobility.•High power efficiency in blue phosphorescent organic light emitting ...diodes.
A hole transport material for use in blue phosphorescent organic light-emitting diodes was developed using an ortho linked terphenyl core structure. The ortho linked terphenyl core was modified with ditolylamine to yield the N4,N4,N4″,N4″-tetra-p-tolyl-1,1′:2′,1″-terphenyl-4,4″-diamine (TTTDA) hole transport material. TTTDA was compared with common 1,3-bis(N-carbazolyl)benzene (mCP) and showed lower driving voltage and higher power efficiency than mCP. The driving voltage was decreased by as much as 1.5V and the power efficiency was improved by 25%.
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► High quantum efficiency of 23.9% in soluble blue device. ► Carbazole–dibenzofuran hybrid bipolar host material. ► Solution processed blue phosphorescent organic light-emitting ...diodes.
Highly efficient solution processed blue phosphorescent organic light-emitting diodes were developed using a carbazole–dibenzofuran hybrid host material. Asymmetric carbazole–dibenzofuran hybrid host material was synthesized by coupling reaction of phenylcarbazole and dibenzofuran, and it showed good film morphology and bipolar charge transport properties after solution coating. Blue phosphorescent organic light-emitting diodes fabricated by spin coating exhibited extremely high quantum efficiency of 23.9%, which was better than any other data reported for solution processed blue phosphorescent organic light-emitting diodes.
New spirobenzoanthrcene-type orange phosphorescent host materials, 9-(spirobenzoanthracene-7,9′-fluorene-2′-yl)-9H-carbazole and 9-(spirobenzoanthracene-7,9′-fluorene-3-yl)-9H-carbazole, with stable ...efficiency roll-off, were prepared by an Ullmann coupling reaction of 2′-bromo-spirobenzoanthracene-7,9′-fluorene and 3-bromo-spirobenzoanthracene-7,9′-fluorene respectively, with carbazole. Orange phosphorescent organic light-emitting diodes with the configuration of indium tin oxide/N,N’-diphenyl-N,N’-bis-4-(phenyl-m-tolylamino)-phenyl-biphenyl-4,4′-diamine/N,N’-di(1-naphthyl)-N,N’-diphenylbenzidine/Host:Ir(pq)2acac/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline/tris(8-hydroxyquinoline)aluminum/LiF/Al were developed using spirobenzoanthracene-fluorene-type carbazole derivatives as a host material and Ir(pq)2acac as a dopant. A device obtained from 9-(spirobenzoanthracene-7,9′-fluorene-2′-yl)-9H-carbazole doped with 3% Ir(pq)2acac showed an orange color purity of (0.599, 0.373) and an efficiency of 14.74 cd/A at 6.0 V. The overall result is a device with an external quantum efficiency (EQE) >8.93% at high brightness but an operating voltage of <6.0 V.
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► New benzoanthracene-7,9′-fluorene-type host materials were prepared. ► Thermally stable and high glass transition temperature up to 125 °C. ► Orange phosphorescence OLEDs with a stable efficiency roll-off were developed. ► An efficiency (14.74 cd/A at 6.0 V) and an external quantum efficiency>8.93%.
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•Highly soluble host material for blue fluorescent organic light-emitting diodes.•Alkyl free molecular design of anthracene host material for soluble devices.•Ortho linked aromatic ...structure for good solubility in organic solvents.
An alkyl free anthracene based host material, 9-(1,1′:2′,1″-terphenyl-2-yl)-10-phenylanthracene (AnTP), was developed as a soluble host material for solution processed blue fluorescent organic light-emitting diodes by increasing the solubility of anthracene type host material using a twisted aromatic substituent. The good solubility of AnTP even without any alkyl substituent allowed solution coating of AnTP based emitting layer and fabrication of solution processed blue fluorescent organic light-emitting diodes with a current efficiency of 3.7cd/A.
Blue light-emitting host materials with a spirobenzodeanthracene-7,9′-fluorene core, 3-10-(naphthalene-1-yl)anthracene-9-ylspirobenzodeanthracene-7,9′-fluorene (NA-SBAF) and ...3-10-(naphthalene-1-yl)anthracene-9-yl-1-methylspirobenzode anthracene-7,9′-fluorene (NA-MSBAF), were designed and synthesized via coupling reactions. Introduction of a spiro group into the anthracene moieties lead to a reduction in crystallization tendency, and a high glass transition temperature was observed. Typical blue fluorescent organic light-emitting diodes with the configuration of ITO/N,N′-di(1-naphthyl)-N,N′-bis(4-diphenylamino)phenyl-biphenyl-4,4′-diamie (60 nm)/N,N,N′,N′-tetra(1-biphenyl)-biphenyl-4,4′-diamine (30 nm)/Host: Dopant (30 nm, 5%)/LG201 (ETL, 20 nm)/LiF/Al were developed using SBAF-type anthracene derivatives as a host material and p-bis(p-N,N-diphenyl-aminostyryl)benzene (DSA-Ph) as a sky-blue dopant material. A device obtained from NA-SBAF doped with DSA-Ph were compared with that of 9,10-dinaphthalene-2-yl-anthracene and showed blue color purity of 0.150 and 0.217, a luminance efficiency of 7.57 cd/A, and an external quantum efficiency >5.15% at 5.0 V.
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•New spirobenzodeanthracene-7,9′-fluorene-type two host materials were prepared.•Two host materials are thermally stable with high Tg of <227 °C.•Sky-blue fluorescence OLEDs with a color purity of (0.150, 0.217) were developed.•Luminescence efficiency was 7.57 cd/A at 5.0 V with an external quantum efficiency of >5.15%.
This paper report on the significantly improved performance of InP/ZnSeS/ZnS quantum dot (QD) devices with multi-functional ligands. These quantum dots in which the monodentate ligand oleylamine is ...coordinated to the shell surface are reacted with the delocalized bipyridine bidentate ligand, where some oleylamine is replaced by bipyridine. The coordination of the delocalized bidentate bipyridine ligand results in many electronic property changes in the QD-LED (light emitting diode) device.
1
H-NMR (nuclear magnetic resonance) and TGA (thermogravimetric analysis) data indicated that up to 60.6% of the native ligands were partially exchanged with the bipyridine lig-ands. Photoluminescence (PL) spectra before and after ligand substitution show a bathochromic shift of about 2.6 nm due to the electrical resonant properties of the bipyridine ligands. QD-LED devices were fabricated using QDs with substituted bipyridine ligand, and significant improvements in the device properties were observed. Here, we first report the ligand dependence of the photo-and the electroluminescence of green InP/ZnSeS/ZnS quantum dots in QD-LED devices.
Deep blue colored, fluorescent, spiro-type host materials, 5-4-(1-naphthyl)phenyl-spirofluorene-7,9′-benzofluorene and 5,9-bis4-(1-naphthyl)phenyl-spirofluorene-7,9′-benzofluorene were designed and ...successfully prepared by the Suzuki reaction. The electroluminescence characteristics of the two compounds as blue host materials doped with blue dopant materials, diphenyl4-(2-1,1;4,1terphenyl-4-yl-vinyl)phenylamine and 1,6-bis(
p-trimethylsilylphenyl)aminopyrene (SPP) were evaluated. The device used comprised ITO/
N,
N′-bis-4-(di-
m-tolylamino)phenyl-
N,
N′-diphenylbiphenyl-4,4′-diamine)/bis
N-(1-naphthyl)-N-phenylbenzidine/Host:5% dopant/tris(8-hydroxyquinolinato)aluminium/Al–LiF. The device obtained from 5-4-(1-naphthyl)phenyl-spirofluorene-7,9′-benzofluorene doped with 1,6-bis(
p-trimethylsilylphenyl)aminopyrene displayed high color purity (0.138, 0.138) and high efficiency (3.70 cd/A at 7 V).
Novel fused ring spiro compounds, 3,9-di(di(p-tolyl))aminospirobenzodeanthracene-7,9′-fluorene (D1) and 3,9-di(di(4-biphenyl))aminospirobenzodeanthracene-7,9′-fluorene (D2) were designed and ...synthesized as fluorescent blue dopant materials. These compounds are light yellowish green in color and emit a sky-blue light in their photoluminescence. They possess a decomposition temperature of over 420 °C and glass transition temperature of 148 °C and 186 °C, respectively. More fused ring compounds, 1-(2-naphthyl)-10-(2-(6-phenyl)naphthyl)spirobenzoijtetraphene-7,9′-fluorene (H3) was used as a blue host material and the electroluminescence (EL) characteristics of such were evaluated. The EL devices made of indium tin oxide (150 nm)/N,N′diphenyl-N,N′-bis4-(phenyl-m-tolyl-amino)phenyl-biphenyl-4,4′-diamine (DNTPD, 60 nm)/N,N,N′,N′-tetra(1-biphenyl)-biphenyl-4,4′-diamine (TBB, 30 nm/H3 hosts: D1 or D2 dopant (30 nm, 5%)/9,10-di(naphthalene-2-yl)anthracen-2-yl-(4,1-phenylene) (1-phenyl-1H-benzodimidazole) (LG201, 20 nm)/LiF (1 nm)/Al (200 nm) were fabricated and characterized. The EL spectra of the devices with films fabricated via vacuum vapor deposition using an H3 host doped with D1 and D2 are similar to the PL spectrum of the solid thin film. At a 5% concentration for D1, a blue-emitting OLED was realized with an emission peak at 472 nm, a maximum luminance efficiency of 8.91 cd/A and an external quantum efficiency of 5.16% with a current density of 11.31 mA/cm2.
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•New spirobenzodeanthracene-7,9′-fluorene-type two dopant materials were prepared.•Two dopant materials are thermally stable with high Tg of <148 °C.•Sky blue fluorescence OLEDs with a color purity of (0.144, 0.261) were developed.•Luminescence efficiency was 8.91 cd/A at 5.0 V with an EQE of >5.60%.
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•High quantum efficiency of 22.1% in blue phosphorescent organic light-emitting diodes.•High glass transition temperature of 149°C.•Carboline derivatives as high triplet energy host ...material.
A α-carboline based high triplet energy material, 9,9′-(5′-(carbazol-9-yl)-1,1′:3′,1″-terphenyl-3,3″-diyl)di-α-carboline (2CbCzT), was designed and synthesized as the thermally stable host material for blue phosphorescent organic light-emitting diodes (PHOLEDs). The 2CbCzT host showed high glass transition temperature of 149°C and high decomposition temperature of 518°C at 5% weight loss. In addition, the 2CbCzT exhibited bipolar charge transport properties due to hole transport type carbazole and electron transport type α-carboline units. Blue PHOLEDs were developed using the high triplet energy 2CbCzT host material and a high quantum efficiency of 22.1% was obtained.
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•Carbazole modified terphenyl based high triplet energy host material.•High quantum efficiency in blue phosphorescent organic light-emitting diodes.•Ortho linked terphenyl core ...structure for host material.
A high triplet energy material derived from carbazole and ortho terphenyl, 3,3′′-di(9H-carbazole-9-yl)-1,1′:2′,1′′-terphenyl (33DCTP), was synthesized as the host material for blue phosphorescent organic light-emitting diodes (PHOLEDs). The 33DCTP host showed high glass transition temperature of 110°C, high triplet energy of 2.77eV, the highest occupied molecular orbital of −6.12eV and the lowest unoccupied molecular orbital of −2.52eV. High efficiency blue PHOLEDs were developed using the 33DCTP host and bis((3,5-difluorophenyl)pyridine) iridium picolinate dopant material, and high quantum efficiency of 23.7% was achieved with a color coordinate of (0.14, 0.28).
