Blue Fluorescent Materials Research Articles

Deep blue fluorescent host materials based on spirobenzofluorene-fluorene dimers and their properties

Abstract Deep blue fluorescent host materials based on the novel spiro[benzo[c]fluorene-7,9′-fluorene] dimers, 5-[spiro[benzo[c]fluorene-7,9′-fluoren]-5-yl] spiro[benzo[c]fluorene-7,9′-fluorene], 9-[spiro[benzo[c]fluorene-7,9′-fluoren]-2′-yl] spiro[benzo[c]fluorene-7,9′-fluorene], and 1,4-bis(spiro[benzo[c]fluorene-7,9′-fluorene]-5-yl)benzene were designed and successfully prepared using the Suzuki coupling reaction. The physical properties of the sprodimers and their electroluminescent characteristics as blue host materials doped with N,N,N′,N′-tetraphenylspiro[benzo[c]fluorene-7,9′-fluorene]-5,9-diamine were investigated. The device configuration used was ITO/N,N′-diphenyl-N,N′-bis[4-(phenyl-m-tolyl-amino)phenyl]biphenyl-4,4′-diamine/N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine/host:5% dopant/tris(8-hydroxyquinoline)aluminum)/LiF. The device obtained from 1,4-bis(spiro[benzo[c]fluorene-7,9′-fluorene]-5-yl)benzene doped with N,N,N′,N′-tetraphenylspiro[benzo[c]fluorene-7,9′-fluorene]-5,9-diamine showed a high color purity of (0.146 and 0.148), efficiency of 7.44 cd A−1 and an external quantum efficiency of 5.60% at 7 V.

Studies of fluorescence/phosphorescence hybrid white organic light-emitting diodes

White organic light-emitting diodes (WOLEDs) have attracted more and more attention due to their wide applications in full-color displays, solid-state lighting sources and backlight sources. Amongst, fluorescence/hosphorescence hybrid WOLEDs are considered as promising device structures in lighting application because of the long lifetime of fluorescence materials and the high efficiency of phosphorescence materials. For fluorescence/hosphorescence hybrid WOLEDs, it is very important to resolve the synergic emission from the singlet excitons of fluorescence materials to the triplet excitons of phosphorescence materials. The design of effective device structures is necessary to avoid the quench between the singlet excitons and triplet excitons. In this paper, we introduced the structure design and performances of fluorescence/phosphorescence hybrid WOLEDs with different structures based on two blue fluorescence materials with different triplet levels. It is experimentally demonstrated that the high effective structure design with charge carrier transport balance and the effective control of exciton distribution in a wide range are keys in realizing high performance fluorescence/phosphorescence hybrid WOLEDs.

<I>N</I>,<I>N</I>-(Diphenylamino)Fluorenylstyrene Derivatives with the Various Heteroatom-Containing Moieties for Blue Organic Light-Emitting Diodes

A series of blue fluorescent materials 1-6 based on N, N-diphenyl aminofluorene styryl derivatives with six heteroatoms (PhOPh, PhSPh, PhSePh, PhPPh2, thiophene and dibenzothiophene), were synthesized and multilayer devices were fabricated. Interestingly, the EL efficiencies were very sensitive to the structural features of dopants in the emitting layers. Particularly, by using 1 as a dopant in emitting layer, a high-efficiency blue OLED was fabricated, showing the maximum luminance of 10420 cd/m2 at 11 V, the luminous efficiency of 8.6 cd/A at 20 mA/cm2, the power efficiency of 3.4 Im/W at 20 mA/cm2 and had a blue color with the CIE coordinates of (0.147, 0.156) at 8.0 V.

Non-Doped Blue OLEDs Based on 9,9′-Dimethylfluorene Containing 10-Naphthylanthracene Derivatives

A series of blue fluorescent materials 1–3 based on 10-(2-napthyl)-anthracene derivatives with the diverse aromatic groups were synthesized and multilayer non-doped devices using them as emitting materials were fabricated. All OLED devices using these materials emit deep blue light of 446–456 nm. In particular, device 3 exhibited highly efficient blue emissions with the luminous efficiency of 3.89 cd/A, a power efficiency of 2.47 lm/W, Quantum Efficiency of 3.03% at 20 mA/cm2, and CIEx,y coordinates of (0.163, 0.149) at 6 V. Also, device 2 showed the efficient deep-blue emission with CIE coordinates of (x = 0.151, y = 0.104) at 6 V.

The mysterious case of the C. elegans gut granule: death fluorescence, anthranilic acid and the kynurenine pathway.

Gut granules are lysosome-like organelles with acidic interiors that are found in large numbers within the intestine of the nematode Caenorhabditis elegans. They are particularly prominent when viewed under ultraviolet light, which causes them to emit intense blue fluorescence. Yet the function of these large and abundant organelles in this heavily-studied model organism remains unclear. One possibility is that they serve as storage organelles, for example of zinc. A new clue to gut granule function is the identification of the blue fluorescent material that they contain as a glycosylated form of anthranilic acid, which is derived from tryptophan by action of the kynurenine pathway. This compound can also serve a surprising role as a natural, endogenous marker of organismal death.

Blue fluorescent emitters: design tactics and applications in organic light-emitting diodes

Organic light-emitting diodes (OLEDs) are competitive candidates for the next generation flat-panel displays and solid state lighting sources. Efficient blue-emitting materials have been one of the most important prerequisites to kick off the commercialization of OLEDs. This tutorial review focuses on the design of blue fluorescent emitters and their applications in OLEDs. At first, some typical blue fluorescent materials as dopants are briefly introduced. Then nondoped blue emitters of hydrocarbon compounds are presented. Finally, the nondoped blue emitters endowed with hole-, electron- and bipolar-transporting abilities are comprehensively reviewed. The key issues on suppressing close-packing, achieving pure blue chromaticity, improving thermal and morphological stabilities, manipulating charge transporting abilities, simplifying device structures and the applications in panchromatic OLEDs are discussed.

Hybrid white organic light-emitting devices based on phosphorescent iridium–benzotriazole orange–red and fluorescent blue emitters

We demonstrate that high color purity or efficiency hybrid white organic light-emitting devices (OLEDs) can be generated by integrating a phosphorescent orange–red emitter, bis[4-(2H-benzotriazol-2-yl)-N,N-diphenyl-aniline-N1,C3] iridium acetylacetonate, Ir(TBT)2(acac) with fluorescent blue emitters in two different emissive layers. The device based on deep blue fluorescent material diphenyl-[4-(2-[1,1′;4′,1″]terphenyl-4-yl-vinyl)-phenyl]-amine BpSAB and Ir(TBT)2(acac) shows pure white color with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.33,0.30). When using sky-blue fluorescent dopant N,N′-(4,4′-(1E,1′E)-2,2′-(1,4-phenylene)bis(ethene-2,1-diyl)bis(4,1-phenylene))bis(2-ethyl-6-methyl-N-phenylaniline) (BUBD-1) and orange–red phosphor with a color-tuning phosphorescent material fac-tris(2-phenylpyridine) iridium (Ir(ppy)3 ), it exhibits peak luminance yield and power efficiency of 17.4cd/A and 10.7lm/W, respectively with yellow-white color and CIE color rendering index (CRI) value of 73.

Magnetic field effects on electroluminescence emanated simultaneously from blue fluorescent and red phosphorescent emissive layers of an organic light-emitting diode

A simple method by employing white organic light-emitting diode (OLED) to simultaneously study the effects of magnetic fields (MFEs) on the fluorescent and phosphorescent emission was presented. The white OLED consisting of the blue fluorescent and red phosphorescent materials was fabricated. The low-pass filter chopped at 500nm and the high-pass filter chopped at 550nm were used to separate the MFEs on the blue fluorescence and red phosphorescence, separately. The magnetoelectroluminescences (MELs) on the fluorescence sharply increased at low magnetic field then tended to saturation at high magnetic field. While the MELs on the phosphorescence sharply increased at low magnetic field then slowly monotonically increased as the magnetic field further increased. Our results indicated that the magnetic-field modulated singlet-to-triplet electron–hole pair conversion combining with the magnetic-field modulated triplet–triplet annihilation process are the origins of the MFEs on the electroluminescence.

Spirobenzofluorene linked anthracene derivatives: Synthesis and application in blue fluorescent host materials

Blue light-emitting anthracene-based host materials with a spiro[benzo[c]fluorene-7,9′-fluorene] core, 5-(10-(naphthalen-2-yl)anthracen-9-yl)spiro[benzo[c]fluorene-7,9′-fluorene] ( NA-SBFF ) and 5-(10-(4-(naphthalen-1-yl)phenyl)anthracen-9-yl)spiro[benzo[c]fluorene-7,9′-fluorene] ( NPA-SBFF ), were designed and synthesized via two-step Suzuki coupling reactions. Introduction of a spiro group into the structure of 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′ -diphenyl- N,N′ -bis[4-(phenyl- m -tolyl-amino)phenyl]biphenyl-4,4′-diamine (DNTPD)/ N,N′ -di(1-naphthyl)- N,N′ -diphenylbenzidine (NPB)/HOST: Dopant/tris(8-hydroxyquinoline)aluminum (Alq 3 )/LiF were developed using SBFF -type anthracene derivatives as a host material and N,N,N′,N′ -tetraphenylspiro[benzo[c]fluorene-7,9′-fluorene]-5,9-diamine ( TPA-SBFF ) as a dopant material. A device obtained from NA-SBFF doped with TPA-SBFF showed blue color purity of 0.146 and 0.167, a luminance efficiency of 8.65 cd/A, and an external quantum efficiency >6.01% at 8.0 V. ► New anthracene host materials with spiro[benzo[c]fluorene-7,9′-fluorene] were prepared. ► Thermally stable and high glass transition temperature up to 263 °C. ► Deep blue fluorescence OLEDs with a color purity of (0.146, 0.167) were developed. ► An efficiency (8.65 cd/A at 8.0 V) and an external quantum efficiency >6.01%.

Deep Blue Fluorescent Host Materials Based on a Novel Spiro[benzo[c]fluorene-7,9'-fluorene] Core Structure with Side Aromatic Wings

E-mail: msgong@dankook.ac.krReceived March 24, 2012, Accepted April 9, 2012Deep blue fluorescent host materials based on a novel spiro[benzo[ c]fluorene-7,9'-fluorene] core structure withside aromatic wings in the 5- and 9-positions, namely, 5,9-di(naphthalen-2-yl)spiro[benzo[c]fluorene-7,9'-fluorene] (DN-SBFF), 5,9-bis(4-t-butylphenyl)spiro[benzo[ c]fluorene-7,9'-fluorene] (BP-SBFF), and 5,9-bis(4-fluorophenyl)spiro[benzo[ c]fluorene-7,9'-fluorene] (FP-SBFF), were designed and successfully pre-pared using the Suzuki reaction. The physical properties of these materials and their EL characteristics as bluehost materials doped with N,N,N',N'-tetraphenylspiro[benzo[c]fluorene-7,9'-fluorene]-5,9-diamine ( TPA-SBFF)were investigated. The device used comprised ITO/ N,N'-diphenyl-N,N'-bis[4-(phenyl-m-tolyl-amino)phenyl]-biphenyl-4,4'-diamine (DNTPD)/N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (NPB)/(FP-SBFF):dopant x%/tris(8-hydroxyquinoline)aluminum (Alq

Blue Fluorescence and Bipolar Transport Materials Based on Anthracene and Their Application in OLEDs

AbstractThe phenomenon of organic electroluminescence (EL) was first discovered from studies on anthracene crystals in the 1960s. Since then, its derivatives have been studied extensively in applications such as organic light‐emitting diodes (OLEDs) and organic thin‐film transistors because of their excellent EL, transport, and good electrochemical properties. A blue fluorescence emitter based on anthracene is also important in constructing hybrid tandem white OLEDs for lighting applications. This article provides a review about the development of blue host OLED materials based on molecules designed and derived from the core structure of anthracene and their application as bipolar charge‐carrier transport materials in OLEDs. The recent development of efficient, stable, blue‐doped p‐i‐n OLEDs with simplified device architecture based on the single common host 2‐methyl‐9,10‐di(2‐napthyl)anthracene, with its stable thin‐film morphology, large band gap energy, high fluorescence quantum yield, and ambipolar charge‐carrier transport properties, is also highlighted.

Cation radii induced structural variation in fluorescent alkaline earth networks constructed from tautomers of a nucleobase analogue

Nucleobase tautomers and their metal complexes have attracted considerable attention due to their fascinating architectures along with wide applications. In this paper, 4,6-dihydroxypyrimidine (H(2)DHP), an analogue of uracil and thymine, was employed to react with the vital elements of alkaline earth metals in an aqueous solution and lead to the formation of four novel complexes, [Mg(HDHP)(2) (H(2)O)(4)] (1), [Ca(HDHP)(2)(H(2)O)(3)](n)·nH(2)O (2), [Sr(HDHP)(2)(H(2)O)(3)](n)·nH(2)O (3), and [Ba(HDHP)(2)(H(2)O)(2)](n)·nH(2)O (4), which have been characterized by elemental analysis, IR, TG, UV-Vis, PL, powder and single-crystal X-ray diffraction and progressively evolve from zero-dimensional (0D) mononuclear, one-dimensional (1D) zig-zag double chain, two-dimensional (2D) double layer, to a three-dimensional (3D) porous network along with the increase of cation radii. This tendency in dimensionality follows salient crystal engineering principles and can be explained by considering factors such as hard-soft acid-base principles and cation radii. The deprotonated H(2)DHP ligand exhibits four new coordination modes, namely, O-monodentate (complex 1), N,O-chelating (complexes 2 and 3), O,O-bridging (complexes 2 and 3), and κ(1)O:κ(2)O-bridging mode (complex 4). Interestingly, the structural investigation indicates that the HDHP(-) monoanion shows three unusual types of tautomers, which are essential for the diagnosis of disease and investigation of medicine. Furthermore, the four complexes exhibit strong blue emission compared to free H(2)DHP ligand at room temperature and may be potential candidates for blue fluorescent biological materials used in organisms.

Multifunctional electron-transporting indolizine derivatives for highly efficient blue fluorescence, orange phosphorescence host and two-color based white OLEDs

In this work, derivatives of indolizine are first used as electron-transporting host materials for hybrid fluorescence/phosphorescence white organic light-emitting devices (F/P-WOLED). Of the indolizine derivatives, a blue fluorescent material BPPI (3-(4,4′-biphenyl)-2-diphenylindolizine) was found to have: (1) blue emission with high quantum yields, (2) good morphological and thermal stabilities, (3) electron-transporting properties, and (4) a sufficiently high triplet energy level to act as a host for red or yellow-orange phosphorescent dopants. The multifunctional BPPI enables adaptation of several simplified device configurations. For example, a non-doped blue fluorescent device exhibits good performance with an external quantum efficiency of 3.16% and Commission Internationale de l'Eclairage coordinates of (0.15, 0.07). A high-performance orange phosphorescent device was found to have a high current efficiency of 23.9 cd A−1. Using BPPI, we also demonstrate a F/P-WOLED with a simplified structure, stable emissions and respectable performance (current and external quantum efficiencies of 17.8 cd A−1 and 10.7%, respectively).

The Application of Environmental Protection Long-Lag Material in Printing Ink of Fluorescent Map

With the development of fluorescent technology, the application area of fluorescent material is expanding, which includes the fields of traffic, national defence, architecture, detection, decoration etc. In the field of printing, whether in the value of utility or view and admire, fluorescent adds tremendous energies. However, a majority of fluorescent materials used nowadays contain radioelement, which will do harm to human health. This paper considers the needs of fluorescent map printing, according to the defects of traditional fluorescent material such as low brightness, short duration time, strong radioactivity, limitation to spot color printing etc. It improves the capability of long fluorescent lag material and makes red, blue, green and yellow long fluorescent lag materials. Meanwhile, it tests the influence of ink thickness, illumination time and granule size etc. on irradiance capability. The thicker the ink is, the longer of the lag time will be. The bigger the granule size is, the lag time will be. It also tests its radioactivity extent, which is in the safety range and reaches the standard of environmental protection. According to the special requirement of map printing, this paper brings forward the technique scheme of the application of long fluorescent lag ink in map printing,which realizes the color fluorescent map printing.

Highly Efficient Blue Organic Light-Emitting Diodes Based on 2-(Diphenylamino)fluoren-7-ylvinylarene Derivatives that Bear a tert-Butyl Group

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).

ChemInform Abstract: Synthesis and Characterization of 9,9′‐Diethyl‐2‐diphenylaminofluorene Derivatives as Blue Fluorescent Materials for OLEDs.

AbstractThe compounds (I) are used as dopant for OLEDs.

Improving the image of an organic light-emitting diode using a dye-polariser

The present work investigated the image improvement of an organic light-emitting diode (OLED) by using a dye-polariser on the panel of an OLED. There are many key vision indexes that can be used to indicate the image performances of flat panel displays (FPDs), such as pixel solution, brightness, view angle, visual reflective sensitivity, contrast ratio, colour saturation and response time. In this study, a dye-polariser was applied on the panel of an OLED and experiments were conducted to examine the image performances using some relative key vision indexes. The results clearly show the effectiveness of the dye-polariser used. The OLED showed a reduction in visual reflective sensitivity by 86.6%, improved the contrast ratio of the image to 2.4 and 2.7 times in an indoor (or office) ambience (490 cd/m2) and an outdoor ambience (1375 cd/m2), respectively, increased colour saturation from 59.4% to 66.7%, and reinforced the weaknesses of the red and blue organic fluorescent materials. © 2011 Canadian Society for Chemical Engineering

Solution-processable 1,3,5-tri(9-anthracene)-benzene cored propeller-shaped materials with high Tg for blue organic light-emitting diodes

This study describes the synthesis and characterization of a series of new blue fluorescent materials, with propeller-like topology, consisting of 1,3,5-tri(9-anthracene)benzene core and various aromatic dendrons, such as naphthalene, 3,5-diphenylbenzene, carbazole, and N, N-diphenylamine. These compounds show excellent thermal and morphological stability with high glass transition temperatures ( T g) (166–231 °C) and high thermal decomposition temperatures ( T d) (427–504 °C). Solution-processable double-layered OLEDs fabricated with these materials as the light-emitting layer show stable blue emission and good performance. The nondoped electronic device fabricated using compound 5c exhibits a maximum brightness of 4754 cd/m 2 and maximum current efficiency of 2.0 cd/A (power efficiency, 1.71 lm/W) with Commission Internationale d’Eclairage (CIE x,y ) color coordinates of ( x = 0.16, y = 0.19) and the devices’ threshold voltage are only 3.4 eV. Compound 5d shows an even higher efficiency of up to 4.90 cd/A with CIE x,y color coordinates of ( x = 0.17, y = 0.31) when doped with a blue fluorescent dopant, 4,4′-bis[4-(di-p-tolylamino)styryl]biphenyl ( DPAVBi).

2‐Diphenylaminofluoren‐7‐ylstyrene Derivatives with Various Aromatic End‐Capping Groups for Highly Efficient Blue and White Organic Light‐Emitting Diodes

AbstractHighly 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.

56.4: New Deep Blue Fluorescent Materials and Their Application to High Performance OLEDs

AbstractWe developed highly efficient deep blue fluorescent materials. The bottom‐emission OLED showed a CIE1931 coordinate of (0.14, 0.08) and a current efficiency of 6.5 cd/A with using a new efficiency‐enhancement layer. We achieved CIEy of 0.062, a current efficiency of 7.5 cd/A and lifetime (LT95) of 2,000 hrs by depositing a new organic capping layer on a top‐emission blue OLEDs, A hybrid white OLED by stacking a deep blue fluorescence and a phosphorescent red/green stacked yellow was also demonstrated which has an efficacy of 23 lm/W and color temperature of 10,000 K at 10 mA/cm2 and lifetime (LT50) of over 60,000 hrs at a luminance of 1,000 cd/m2.