Blue Fluorescent Materials Research Articles

Diphenylaminoarylvinyl-Substituted Diphenylanthracenes for Organic Light-Emitting Diodes.

Two blue fluorescent materials based on diphenylaminoarylvinyl-substituted diphenylanthracene have been synthesized. Multilayered organic light-emitting diodes (OLED) with the following sequence; ITO/NPB (50 nm)/Blue materials (30 nm)/Bphen (30 nm)/Liq (2 nm)/Al (100 nm) were fabricated using these materials as emitters. Two devices exhibited blue electroluminescence. Particularly, a device using 6-(4-(10-phenylanthracen-9-yl)styryl)-N,N-diphenylnaphthalen-2-amine (2) exhibited blue emission with a luminance efficiency, a power efficiency, an external quantum efficiency and CIE coordinates of 5.69 cd/A, 1.99 lm/W, 3.39% at 100 mA/cm² and (x = 0.19, y =0.31) at 8.0 V, respectively.

Highly efficient dual-core derivatives with EQEs as high as 8.38% at high brightness for OLED blue emitters

Three blue fluorescent materials were newly synthesized. A device doped with p-TPA-AP-TPA displayed a very high efficiency of 9.14 cd A−1 and an EQE of 8.38% at a high luminance of 5000 cd m−2.

基于扭曲A-π-D-π-A构型的蓝色荧光材料的π-共轭桥与光物理特性间的关系

基于扭曲A-π-D-π-A构型的蓝色荧光材料的π-共轭桥与光物理特性间的关系

Efficient Deep-Blue Electrofluorescence with an External Quantum Efficiency Beyond 10%

SummaryThe design of blue fluorescent materials combining both deep-blue emission (CIEy<0.06) and high-efficiency climbing over the typically limited exciton production efficiency of 25% is a challenge for organic light-emitting diodes (OLEDs). In this work, we have synthesized two blue luminogens, trans-9,10-bis(2-butoxyphenyl)anthracene (BBPA) and trans-9,10-bis (2,4-dimethoxyphenyl)anthracene with high photoluminescence quantum yields (PLQYs) of 89.5% and 87.0%, respectively. Intriguingly, we have proposed a strategy to avoid aggregation-caused quenching, which can effectively reduce the undesirable excimeric emission by introducing two host matrices with twisted molecular structure, 9,10-di(naphth-2-yl) anthracene and 10,10′-bis-(4-fluorophenyl)-3,3′-dimethyl-9,9′-bianthracene (MBAn-(4)-F), in the BBPA emission layer. The device containing the EML of BBPA-doped MBAn-(4)-F exhibited a high external quantum efficiency of 10.27% for deep-blue emission with the Commission International de L'Eclairage CIE coordinates of (0.15, 0.05) via the steric effect. Importantly, this represents an advance in deep-blue-emitting fluorescent OLED architectures and materials that meet the requirements of high-definition display.

A novel bipolar carbazole/ phenanthroimidazole derivative for high efficiency nondoped deep-blue organic light-emitting diodes

Abstract It is still a matter of worldwide continuous concern about how to obtain efficient, stable, pure blue light emitting materials and apply them in industrialized OLED devices. Here, a novel deep blue fluorescent material 2-(4'-(9H-carbazol-9-yl)-[1,1′-biphenyl]-4-yl)-1-(4-methoxyphenyl)-1H-phenanthro [9,10-d]imidazole(CzB-MOPPI) was firstly designed, synthesized and employed as emitters for deep-blue OLEDs. CzB-MOPPI, with carbazole as donor, twisted biphenyl bonded phenanthroimidazole which contains rigid plane structure as acceptor, exhibits high thermal stability with decomposition temperature (Td) of 480 °C. Weak donor carbazole unit and twist biphenyl both make the compound emit less red shift meanwhile maintain in deep blue region. The non-doped OLEDs based on the CzB-MOPPI as emitter show maximum emission at 435 nm, maximum luminance of 6450 cd/m2, maximum current efficiency (CE) of 3.34 cd/A. The chromaticity coordinate is (0.16, 0.08) which is extremely close to the NTSC standard blue. In Particular, the devices show an impressive external quantum efficiency (EQE) as high as 5.97%.

Thermal Stability and Luminescent Properties of Tri-cellulose Acetate Composites Containing Dy(SSA)3Phen Complex

Dysprosium (Dy) ternary complex was prepared using 5-sulfosalicylic acid (SSA) as the first ligand and 1,10-phenanthroline (Phen) as the second ligand, denoted as Dy(SSA)3Phen. The complex was blended with tri-cellulose acetate (TCA) via a cosolvent method to obtain polymer luminescent materials. The composition and structure of the rare-earth complex were characterized by means of elemental analysis, infrared (IR) spectra, and thermogravimetric analysis (TGA). The fluorescence spectra displayed this pure Dy(SSA)3Phen complex, and the TCA/Dy(SSA)3Phen composites all emit blue light. The (90/10) composite possesses fine luminescent properties with quantum yield of 33.5% and thermal stability for potential usage as blue fluorescent materials.

Highly Efficient Deep Blue Fluorescent Organic Light-Emitting Diodes Boosted by Thermally Activated Delayed Fluorescence Sensitization.

Highly efficient deep blue fluorescent material and various thermally activated delayed fluorescent (TADF) blue sensitization materials were synthesized for fluorescent deep blue organic light-emitting diodes (OLEDs). These materials were designed and selected by considering efficient energy transfer conditions (i.e., spectral overlap and quantum efficiency) between sensitizer and acceptor. Energy transfer process from TADF host sensitizers to deep blue fluorescent emitter has been investigated by measuring the energy transfer rate. Measured energy transfer rate was to be 1.24 × 1010 s-1 (mol/dm3)-1 for a prompt decay of fluorescence and 2.61 × 108 s-1 (mol/dm3)-1 for delayed fluorescence, which demonstrated the efficient energy transfer. Indeed, highly efficient deep blue fluorescent OLEDs boosted by the TADF host-sensitization process were successfully fabricated. The maximum external quantum efficiency was 19.0% with color coordinates of (0.14, 0.15) and 15.5% with color coordinates of (0.15, 0.11) in the different host system. The efficiency roll-off characteristic and device operating lifetime were also improved by this efficient sensitization process.

Blue organic light-emitting diodes based on spiro[fluorene-indeno]pyridine derivatives

ABSTRACTWe designed and synthesized two blue fluorescent materials based on spiro[9H-fluorene-9, 5′-[5H] indeno[1, 2-b] pyridine via Buchwald-Hartwig amination and Suzuki coupling reaction. To characterize their electroluminescent properties, multilayered organic light emitting diodes (OLEDs) were fabricated with the following device structures: ITO(180 nm)/2-TNATA(60 nm)/NPB(20 nm)/α,β-ADN: 3, 5, or 10 wt% blue dopants (30 nm)/Bphen(30 nm)/Liq(2 nm)/Al(100 nm). All the devices showed blue emissions with high electroluminescent efficiencies. Particularly, a device using 7′-((4-(N,N-diphenyl)-styryl)-4-phenyl)-spiro[9H-fluorene-9, 5′-[5H] indeno[1, 2-b] pyridine] as a dopant material with 10 wt% doping concentration exhibited highly efficient blue emission with an external quantum efficiency of 4.46% at 20 mA/cm2 and the CIE coordinates of (0.18, 0.30) at 1000 cd/m2. In this device, the twisted structural feature of emitter originated from spiro-type core prevented self-quenching and lead to the improved efficiencies even at high doping concentration in the device.

高激子利用率的蓝光荧光材料及其激发态性质

高激子利用率的蓝光荧光材料及其激发态性质

Luminescence properties of tricellulose acetate composites emitting blue light

A series of dinuclear complexes with molar ratios of cerium to lanthanum of 1:0, 1:1, 1:2, 1:4, 1:7, 1:9 and 0:1 was synthesized using 5-sulfosalicylic acid (SSA) as the first ligand and 1,10-phenanthroline (Phen) as the second ligand, recorded as Ce1−x La x (SSA)3Phen (x = 0, 0·5, 0·67, 0·8, 0·875, 0·9, 1), and the complexes were blended with tricellulose acetate (TCA) to obtain luminescent polymer materials. The compositions and structures of the rare earth complexes were determined through elemental analysis, energy-dispersive X-ray analysis, infrared spectroscopy and thermogravimetric analysis. Under the optimum excitation wavelengths, all dinuclear complexes emitting blue light displayed the characteristic emission of the cerium (Ce3+) ion. The fluorescence spectra showed that the 85:15 TCA/Ce0·2La0·8(SSA)3Phen composite showed the strongest fluorescence among all composites and the quantum efficiency was calculated as 30·6%. The introduction of the lanthanum (La3+) ion into the cerium ion complex can effectively reinforce the luminescence intensity of the complex and be favorable for retaining the excellent fluorescence in the TCA matrix. The 85:15 TCA/Ce0·2La0·8(SSA)3Phen composite possesses fine luminescence properties and thermal stability for potential usage as a blue fluorescent material.

Na2(H2en)[B5O8(OH)]2[B3O4(OH)]2 and Na3(HCOO)[B5O8(OH)]: Two Borates Co‐Templated by Inorganic Cations and Organic Compounds

The cooperative effect of inorganic and organic co‐templates led to two layered borates: centrosymmetric (CS) Na2(H2en)[B5O8(OH)]2[B3O4(OH)]2 (1; en = ethylenediamine) and noncentrosymmetric (NCS) Na3(HCOO)[B5O8(OH)] (2). Compound 1 features coupled layers extended by two different oxoboron clusters, which are rare in borates. The Na+ cations are located in the channel and hold the coupled layers in tight inorganic B–O–Na layers, while H2en2+ cations reside in channels between inorganic layers. Compound 2 is the first NCS borate directed by inorganic and organic species simultaneously and features acentric [B5O8(OH)]n2n– layers. It exhibits a good second harmonic generation efficiency of about 1.9 times that of potassium dihydrogenphosphate and is phase‐matchable, and the UV cutoff edge below 200 nm makes 2 a potential UV nonlinear optical material. Investigation of the fluorescence properties indicated that the new borates are potential blue fluorescent materials. In addition, structure elucidation revealed that host–guest symmetry matching plays a key role in the formation of CS 1 and NCS 2.

Preparation of 9,10-diarylphenanthrene derivative and its application in full color emitters synthesis

As a building block with high photo- and thermo-stability, phenanthrene plays an important role in the preparation of blue(or deep-blue) and full color fluorescence materials. However, some critical issues must be addressed before its full potential can be realised, such as its tedious and low-yield modification processes and the red-shift effect in its aggregated state. In this work, the inexpensive raw material 9,10-phenanthrenequinone(PQ) was chosen as the preparatory functional phenanthrene block. After modifying PQ via halo-substituted, nucleophilic and rearrangement reactions with high yields, the corresponding monomers featured high reactivity and solubility. Compared with classical synthetic approaches for similar phenanthrene-based derivatives, the low efficiency ring-closed reaction and hazardous lithium-injection operation can be omitted using this approach. This new building block demonstrates a clear steric effect following the introduction of peripheral phenyl and alkoxy groups; moreover, stacking in the aggregated state is avoided, which benefits controlling the bandgap and maintaining blue emission as either an emitter or a donor. By changing the central building block in three oligomers, emission of the three primary colors was achieved in solution and film via the conjugated increment and charge-transform effect. This work provides a method of modifying phenanthrene by a simple and efficient synthesis route with inhibition of solid-state aggregation and offers an effective strategy to further develop functional phenanthrene-based building blocks.

Synthesis, photophysical, electrochemical and theoretical studies of the novel indolo[3,2-b]indole derivatives

A series of novel indolo[3,2-b]indole derivatives as blue-light-emitting materials were designed and synthesized by Pd (Ⅱ) catalyzed Suzuki coupling reaction in good yields. The thermal, photophysical, electrochemical properties of the derivatives were investigated and compared by introducing different terminal aromatic units into the target compounds. The results indicated that these new compounds exhibited high thermal stabilities, good solubility, stably blue fluorescent properties and good electronic transmission abilities. All the target compounds showed the potential to be used as blue fluorescent materials.

A three-dimensional ZnII coordination polymer constructed from 1,1'-biphenyl-2,2',4,4'-tetracarboxylate and 1,4-bis(1H-imidazol-1-yl)benzene ligands exhibiting photoluminescence.

Ligands based on polycarboxylic acids are excellent building blocks for the construction of coordination polymers; they may bind to a variety of metal ions and form clusters, as well as extended chain or network structures. Among these building blocks, biphenyltetracarboxylic acids (H4bpta) with C2 symmetry have recently attracted attention because of their variable bridging and multidentate chelating modes. The new luminescent three-dimensional coordination polymer poly[(μ5-1,1'-biphenyl-2,2',4,4'-tetracarboxylato)bis[μ2-1,4-bis(1H-imidazol-1-yl)benzene]dizinc(II)], [Zn2(C16H6O8)(C12H10N4)]n, was synthesized solvothermally and characterized by single-crystal X-ray diffraction, elemental analysis and IR spectroscopy. The crystal structure contains two crystallographically independent ZnII cations. Both metal cations are located on twofold axes and display distorted tetrahedral coordination geometries. Neighbouring ZnII centres are bridged by carboxylate groups in the syn-anti mode to form one-dimensional chains. Adjacent chains are linked through 1,1'-biphenyl-2,2',4,4'-tetracarboxylate and 1,4-bis(1H-imidazol-1-yl)benzene ligands to form a three-dimensional network. In the solid state, the compound exhibits blue photoluminescence and represents a promising candidate for a thermally stable and solvent-resistant blue fluorescent material.

An efficient solvent free Amberlite IRA-400 Cl resin mediated multicomponent synthesis and photophysical properties of fluorescent 4H-chromene derivatives

An efficient Amberlite IRA-400 Cl basic anion exchange resin mediated multicomponent reaction of 2-hydroxybenzaldehydes, 1, 3-diketone and nucleophiles under neat condition afforded a number of fluorescent 4H-chromene derivatives in excellent yield. The structure of the synthesized compounds 4k and 4u were confirmed from single crystal XRD studies. 4H-Among the chromene derivatives, compound 4v synthesized from 4-diethylamino substituted 2-hydroxybenzaldehyde with dimedone and 2-hydroxynaphthaquinone has been found best florescent material. Photophysical properties such as solvatochromic effect, absorption, emission, Stocks shift and quantum yield of the selected compounds have been evaluated. The emission properties of the synthesized compounds suggested that these are a class of blue emissive fluorescent materials.

Efficient hybrid white organic light-emitting diodes for application of triplet harvesting with simple structure

In this study, we fabricated hybrid white organic light-emitting diodes (WOLEDs) based on triplet harvesting with simple structure. All the hole transporting material and host in emitting layer (EML) of devices were utilized with same material by using N,N'-di-1-naphthalenyl-N,N'-diphenyl-[1,1':4',1":4",1"'-quaterphenyl]-4,4"'-diamine (4P-NPD) which were known to be blue fluorescent material. Simple hybrid WOLEDs were fabricated three color with blue fluorescent and green, red phosphorescent materials. We was investigated the effect of triplet harvesting (TH) by exciton generation zone on simple hybrid WOLEDs. Characteristic of simple hybrid WOLEDs were dominant hole mobility, therefore exciton generation zone was expected in EML. Additionally, we was optimization thickness of hole transporting layer and electron transporting layer was fabricated a simple hybrid WOLEDs. Simple hybrid WOLED exhibits maximum luminous efficiency of 29.3 cd/A and maximum external quantum efficiency of 11.2%. Commission Internationale de l'Eclairage (International Commission on Illumination) coordinates of (0.45, 0.43) at about 10,000 cd/m^2.

N-(4-tert-Butylphenyl)-N-phenyl-4-(9,10-diphenylanthracen-3-yl)benzenamine for blue organic light-emitting diodes

In this study, we have synthesized two blue fluorescent materials based on anthracene derivatives with electron-donating diphenylamine moieties by Suzuki cross-coupling reactions. To explore their electroluminescent properties as blue emitting materials, multilayer devices were fabricated in following sequence: indium–tin-oxide (180 nm)/4,4′-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (50 nm)/blue emitters (30 nm)/bathophenanthroline (30 nm)/lithium quinolate (2 nm)/Al (100 nm). Among them, a device using N-(4-tert-butylphenyl)-N-phenyl-4-(9,10-diphenylanthracen-3-yl)benzenamine exhibited efficient blue emission with a luminous, power and external quantum efficiency of 3.11 cd/A, 2.39 lm/W, and 1.82% at 20 mA/cm2, respectively. The Commission International de L’Eclairage coordinates of this device were at 6.0 V.

Efficient blue fluorescent electroluminescence based on a tert-butylated 9,9′-bianthracene derivative with a twisted intramolecular charge-transfer excited state

An orthogonally twisting tert-butylated 9,9′-bianthracene derivative, namely 10,10′-bis(4-tert-butylphenyl)-9,9′-bianthracene (BAn-(4)-tBu), possessing high thermal stability and high luminescence efficiency was synthesized. The BAn-(4)-tBu emitter with a twisted intramolecular charge transfer state characteristics, originating from its twisting 9,9′-bianthracene moiety, enhanced the occurrence of singlet excitons in the fluorescent emitter. The BAn-(4)-tBu device doped with sky blue fluorescent material 4,4-bis[4-(di-p-tolylamino)styryl]biphenyl displayed a maximum singlet generation fraction of >25%, maximum current and external quantum efficiencies of 6.00cdA−1 and 3.22%, respectively. Remarkably, a low efficiency roll-off was observed. These results demonstrated that BAn-(4)-tBu as a host material is advantageous for fabrication of highly efficient blue fluorescent organic light-emitting devices.

Thermal Plasma Synthesis of Crystalline Gallium Nitride Nanopowder from Gallium Nitrate Hydrate and Melamine.

Gallium nitride (GaN) nanopowder used as a blue fluorescent material was synthesized by using a direct current (DC) non-transferred arc plasma. Gallium nitrate hydrate (Ga(NO3)3∙xH2O) was used as a raw material and NH3 gas was used as a nitridation source. Additionally, melamine (C3H6N6) powder was injected into the plasma flame to prevent the oxidation of gallium to gallium oxide (Ga2O3). Argon thermal plasma was applied to synthesize GaN nanopowder. The synthesized GaN nanopowder by thermal plasma has low crystallinity and purity. It was improved to relatively high crystallinity and purity by annealing. The crystallinity is enhanced by the thermal treatment and the purity was increased by the elimination of residual C3H6N6. The combined process of thermal plasma and annealing was appropriate for synthesizing crystalline GaN nanopowder. The annealing process after the plasma synthesis of GaN nanopowder eliminated residual contamination and enhanced the crystallinity of GaN nanopowder. As a result, crystalline GaN nanopowder which has an average particle size of 30 nm was synthesized by the combination of thermal plasma treatment and annealing.

Fluoranthene derivatives as blue fluorescent materials for non-doped organic light-emitting diodes

In this study, we report synthesis of symmetrically and non-symmetrically functionalized fluoranthene-based blue fluorescent molecular materials for non-doped electroluminescent devices.