Bright Green Light Research Articles

Luminescent polypropylene fibers containing novel organic luminescent substance

Novel organic luminescent substance (3,12-bis(dibutylamine)-7,8-dicyano-5,6,9,10-tetrahydro[5]helicene; M123) was successfully synthesized and employed to prepare luminescent polypropylene (PP/M123) fibers of different cross-sectional shapes via melt spinning. For all cross-sectional shapes (circular, hollow triangular, flat, star, and W), the PP/M123 fibers were continuously spun without fiber breakage, and possessed smooth surfaces. The designed structure of M123, containing 4 butyl groups, enabled its homogeneous mixing with hydrophobic polypropylene matrix. Addition of M123 did not alter the PP melt flow through complex spinneret orifices during fiber spinning, as evidenced by rheological measurements that melt viscosities of PP and PP/M123 at different shear rates (10–10,000 s−1) were almost identical. Results from differential scanning calorimetry also confirmed homogeneity of M123 and PP matrix as the melting temperatures and crystallinities of PP/M123 fibers were comparable to those of PP fibers. By employing organic luminescent M123, the processes of additive preparation and additive/polymer compounding were simplified, and small amount of luminescent substance as 0.05 % wt. could be used to yield effective luminescence. The PP/M123 fibers exhibited yellowish green color under normal light and emitted bright green light under ultraviolet (UV) light.

Luminescent properties of Ca3SiO4Cl2 co-doped with Ce(3+) and Eu(2+) for near-ultraviolet light-emitting diodes.

Ca3SiO4Cl2 co-doped with Ce(3+),Eu(2+) was prepared by high temperature reaction. The structure, luminescent properties and the energy transfer process of Ca3SiO4Cl2:Ce(3+),Eu(2+) were investigated. Eu(2+) ions can give enhanced green emission through Ce(3+) → Eu(2+) energy transfer in these phosphors. The green phosphor Ca2.9775SiO4Cl2:0.0045Ce(3+),0.018Eu(2+) showed intense green emission with broader excitation in the near-ultraviolet light range. A green light-emitting diode (LED) based on this phosphor was made, and bright green light from this green LED could be observed by the naked eye under 20 mA current excitation. Hence it is considered to be a good candidate for the green component of a three-band white LED.

선박평형수 처리 시스템 효율 검증을 위한 해양 플랑크톤 생사판별시 Neutral red 염색법 적용 가능성 연구

In order to prevent the spread of non-indigenous aquatic species through the ballast water in commercial ships, International Maritime Organization (IMO) adopted in 2004 the International Convention for Control and Management of Ship`s Ballast Water and Sediments. The Convention mandates treatment of ballast water for most transoceanic voyages and its confirmation of treatment is made with plankton live/dead assay. Fluorescein diacetate assay (FDA), which produces bright green light for live phytoplankton, has been a de facto standard method to determine the survival of marine plankton, but its staining efficacy has been in dispute. In the present study, we examined the limitation of FDA, and compared its efficacy with Neutral red (NR) staining, another promising assay and widely used especially for zooplankton mortality. For all phytoplankton species studied in the present study, except Ditylum brightwellii, the staining efficiency was

Special Tm3+transition and white upconversion luminescence in the Yb3+/Tm3+co-doped KMnF3

Special Tm3+ transition and a bright green light emission is first observed in the Yb3+/Tm3+ co-doped KMnF3, which are synthesized by the molten salt synthesis method. The RGB light emissions are simultaneously obtained with a single Tm3+ activator, and white upconversion luminescence is observed only by changing the reaction time.

Tetraphenylethylene-based phosphine: tuneable emission and carbon dioxide fixation.

A tetraphenylethylene-based phosphine, 1,1,2,2-tetrakis((4-diphenylphosphino)phenyl)ethylene (TPE-P4), was synthesized and showed novel aggregation-induced and mechano-responsive emission. A mixture of TPE-P4 and Ag(+) could fix atmospheric CO2in situ as carbonate ions in neutral solution to yield a rare 3D metal-organic framework with zeolite-like SOD topology, [Ag2(TPE-P4)CO3]x⊃nH2O (Ag-TPE-P4). Ag-TPE-P4 showed turn-on luminescence of TPE-P4, emitting bright bluish green light in the solid state.

Fine tunable red-green upconversion luminescence from glass ceramic containing 5%Er3+:NaYF4 nanocrystals under excitation of two near infrared femtosecond lasers

In this paper, we report fine tunable red-green upconversion luminescence of glass ceramic containing 5%Er3+: NaYF4 nanocrystals excited simultaneously by two near infrared femtosecond lasers. When the glass ceramic was irradiated by 800 nm femtosecond laser, weak red emission centered at 670 nm was detected. Bright red light was observed when the fs laser wavelength was tuned to 1490 nm. However, when excited by the two fs lasers simultaneously, the sample emitted bright green light centered at 550 nm, while the red light kept the same intensity. The dependences of the red and the green light intensities on the two pump lasers are much different, which enables us to manipulate the color emission by adjusting the two pump laser intensities, respectively. We present a theoretical model of Er3+ ions interacting with two fs laser fields, and explain well the experimental results.

Iridium(III) complexes with phenyl-tetrazoles as cyclometalating ligands.

Ir(III) cationic complexes with cyclometalating tetrazolate ligands were prepared for the first time, following a two-step strategy based on (i) a silver-assisted cyclometalation reaction of a tetrazole derivative with IrCl3 affording a bis-cyclometalated solvato-complex P ([Ir(ptrz)2(CH3CN)2](+), Hptrz = 2-methyl-5-phenyl-2H-tetrazole); (ii) a substitution reaction with five neutral ancillary ligands to get [Ir(ptrz)2L](+), with L = 2,2'-bypiridine (1), 4,4'-di-tert-butyl-2,2'-bipyridine (2), 1,10-phenanthroline (3), and 2-(1-phenyl-1H-1,2,3-triazol-4-yl)pyridine (4), and [Ir(ptrz)2L2](+), with L = tert-butyl isocyanide (5). X-ray crystal structures of P, 2, and 3 were solved. Electrochemical and photophysical studies, along with density functional theory calculations, allowed a comprehensive rationalization of the electronic properties of 1-5. In acetonitrile at 298 K, complexes equipped with bipyridine or phenanthroline ancillary ligands (1-3) exhibit intense and structureless emission bands centered at around 540 nm, with metal-to-ligand and ligand-to-ligand charge transfer (MLCT/LLCT) character; their photoluminescence quantum yields (PLQYs) are in the range of 55-70%. By contrast, the luminescence band of 5 is weak, structured, and blue-shifted and is attributed to a ligand-centered (LC) triplet state of the tetrazolate cyclometalated ligand. The PLQY of 4 is extremely low (<0.1%) since its lowest level is a nonemissive triplet metal-centered ((3)MC) state. In rigid matrix at 77 K, all of the complexes exhibit intense luminescence. Ligands 1-3 are also strong emitters in solid matrices at room temperature (1% poly(methyl methacrylate) matrix and neat films), with PLQYs in the range of 27-70%. Good quality films of 2 could be obtained to make light-emitting electrochemical cells that emit bright green light and exhibit a maximum luminance of 310 cd m(-2). Tetrazolate cyclometalated ligands push the emission of Ir(III) complexes to the blue, when compared to pyrazolate or triazolate analogues. More generally, among the cationic Ir(III) complexes without fluorine substituents on the cyclometalated ligands, 1-3 exhibit the highest-energy MLCT/LLCT emission bands ever reported.

Synthesis and Luminescence Properties of Trivalent Rare-Earth Element-Doped Calcium Stannate Phosphors

ABSTRACT The phosphors of calcium stannate activated with individual trivalent rare-earth element (REE) ions (Neodymium III, Europium III, Terbium III, Dysprosium III, and Samarium III) were synthesized by high-temperature solid-state reaction (SSR), and their characterization and luminescent properties were investigated. The crystal structures and morphologies of the resultant materials were well characterized by experimental techniques such as X-ray powder diffraction (XRD) and environmental scanning electron microscopy (ESEM). The XRD results display that the rare-earths substitution of Calcium II does not change the structure of calcium stannate host. Obviously, the ESEM image exhibits that phosphors aggregate and their particles with irregular shape exist. The calcined powders of the Europium III, Neodymium III, Samarium III, Dysprosium III, and Terbium III ions doped in calcium stannate exhibits bright red, reddish orange, yellowish, orange white, and green light, respectively. Although there is some intrinsic emission ranging from UV to near-infrared (NIR) due to the host lattice, the dominant signals are from the rare-earth sites, with signals characteristic of the trivalent rare-earth states. The emission spectrum from undoped-calcium stannate phosphor is characterized by two broad bands centered at ∼800 and ∼950 nm. The shapes of the emission bands are different for each dopant. The sharp emission properties show that the calcium stannate is a suitable host for rare-earth ion-doped phosphor material. Furthermore the influence of different rare-earth dopants, that is, Europium III, Neodymium III, Samarium III, Dysprosium III, and Terbium III, on thermally stimulated luminescence (TSL) of calcium stannate phosphor under the beta irradiation was discussed. Among these trivalent rare-earth-doped phosphors samarium-doped material showed maximum TSL sensitivity with favorable glow curve shape.

A luminescent terbium metal-organic framework for selective sensing of nitroaromatic compounds in high sensitivity

A novel luminescent terbium metal-organic framework [Tb(HL)(H2O)4]·H2O (1) has been successfully prepared by the facile hydrothermal reaction of Tb(NO3)3·6H2O and the π-conjugated ligand H4L (H4L=1,1′-biphenyl-2,3,3′,5′-tetracarboxylic acid). Single crystal structure analysis reveals that 1 exhibits a 2D layered structure. The solid sample of 1 emits high bright green light which can be readily observed by the naked eye when excited at 288nm at ambient temperature. Interestingly, the luminescence of fine grinding 1 particles dispersed in ethanol can be selectively and sensitively quenched by nitroaromatic compounds, which indicates that 1 is a potential luminescent sensory material for nitro explosives.

Efficient organic light-emitting diodes with low efficiency roll-off at high brightness using iridium emitters based on 2-(4-trifluoromethyl-6-fluoro phenyl)pyridine and tetraphenylimidodiphosphinate derivatives

Using 2-(4-trifluoromethyl-6-fluorophenyl)pyridine (tfmfppy) as the cyclometalated ligand and tetraphenylimidodiphosphinate (tpip) derivatives as ancillary ligands, three iridium complexes (1: Ir(tfmfppy)2tpip; 2: Ir(tfmfppy)2ftpip, ftpip = tetra(4-fluorophenyl)imidodiphosphinate; 3: Ir(tfmfppy)2tfmtpip, tfmtpip = tetra(4-trifluoromethylphenyl)imidodiphosphinate) showing phosphorescence at 514, 513 and 508 nm in CH2Cl2 were synthesized, respectively. By using these complexes as emitters, the organic light emitting diodes with the concise configuration of indium tin oxides/1,1-bis(4-(di-p-tolyl-amino)phenyl)cyclohexane (60 nm)/1 or 2 or 3: bis[3,5-di(9H-carbazol-9-yl)phenyl]di-phenyl silane (8 wt%, 30 nm)/1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (90 nm)/lithium fluoride (1 nm)/aluminium (100 nm) showed bright green light with maximum luminance higher than 40 000 cd m−2. The maximum current efficiency (ηc) values for 1, 2 and 3 based devices (GIr1, GIr2 and GIr3) were 77.49, 66.57, and 53.26 cd A−1 at relatively high brightness of 8025, 5286 and 5169 cd m−2, respectively. In addition, the efficiency roll-off ratios from the peak efficiency to the brightness of 10 000 cd m−2 are less than 10% for all the devices. We believe that the good electron mobilities of the phosphorescent emitters lead to the high devices efficiency and low efficiency roll-off. The results suggest that these complexes have potential application in organic light emitting diodes.

Influence of SiO2 coating on morphology, phase and upconversion luminescence properties of NaYF4:Yb3+,Er3+ submicrocubes during annealing

NaYF4:Yb3+,Er3+ submicrocubes were synthesized by a facile method at room temperature, and they were coated with SiO2 using a modified Stöber procedure. Then bare NaYF4:Yb3+,Er3+and NaYF4:Yb3+,Er3+@SiO2 submicrocubes were both annealed at 300°C, 400°C and 500°C for 5h under N2 protection. The influence of SiO2 shells on morphology, phase and upconversion luminescence properties of NaYF4:Yb3+,Er3+ submicrocubes during annealing was studied in detail. The results showed that silica shells can protect NaYF4:Yb3+,Er3+ cores from aggregating and growing up. Interestingly, SiO2 shells can also prevent phase change of NaYF4:Yb3+,Er3+ submicrocubes from cubic (α-) to hexagonal (β-) phase during annealing, which provides a new way to control the phase of NaYF4 nanocrystals. NaYF4:Yb3+,Er3+cores became nanoporous after annealing, making them possess a feature of ‘cavity’ structure for the storage/delivery of therapeutic drugs. After annealing, NaYF4:Yb3+,Er3+ and NaYF4:Yb3+,Er3+@SiO2 submicrocubes both emit bright green light excited with a 980nm laser source, and the upconversion luminescence properties were investigated in detail.

Synthesis and photoluminescence properties of a new green emitting phosphor La2SrB10O19:Tb3+

A new green phosphor, La2SrB10O19:Tb3+ (LSB:Tb) has been prepared by solid-state reaction method. Structural characterization of LSB:Tb has been carried out with X-ray powder diffraction (XRD) analysis. Photoluminescence properties of the phosphor have been investigated by measuring the excitation and emission spectra. The results exhibit that LSB:Tb phosphor has the strongest excitation at 368nm with a full-width at half-maximum (FWHM) of 16nm, and can emit bright green light at 542nm under 368nm excitation. The optimum concentration for Tb3+ in LSB is 8mol%.

Geminal Tetraauration of Acetonitrile: Hemilabile-Phosphine-Stabilized Au8Ag4 Cluster Compounds

Unprecedented geminal tetraauration of acetonitrile has been realized through C-H activation by Au(I)-Ag(I) clusters under mild conditions. The reaction of [OAu3Ag(dppy)3](BF4)2 (dppy = diphenylphosphino-2-pyridine) (1), AgBF4, and acetonitrile in the presence of methanol at room temperature resulted in the isolation of the novel cluster [(CCN)2Au8Ag4(dppy)8(CH3CN)2](BF4)6 (2). The centrosymmetric structure consists of two Au4Ag2 motifs stabilized by hemilabile phosphines. Triply deprotonated acetonitrile (CCN(3-)) is found in a Au4Ag environment with the terminal carbon bridging four Au(I) centers and the nitrogen donor linking a Ag(I) ion, which is the first example of a μ5-CCN(3-) coordination mode. A concerted metalation/deprotonation process for the C-H activation of acetonitrile that indicates the importance of the oxo ion of the oxonium Au(I) cluster is proposed. Cluster 2 emits bright green light in the solid state at room temperature upon UV irradiation.

Enhancing the efficiency of alternating current driven organic light-emitting devices by optimizing the operation frequency

We report efficient and bright organic light-emitting devices operated by capacitive energy coupling. In this approach, the organic layers are enclosed between sputter-deposited hafnium dioxide layers to prevent charge carrier injection. When a sinusoidal voltage signal is applied to the electrodes, the devices emit bright green light whereas no detectable emission is generated upon application of a constant voltage. The efficiency of the process depends heavily on the frequency of the applied voltage signal. By optimizing the driving scheme, a record luminous efficacy for AC driven OLEDs of 2.7lm/W at 500cd/m2 is achieved.

Rational morphology control of β-NaYF4:Yb,Er/Tm upconversion nanophosphors using a ligand, an additive, and lanthanide doping

We report the systematic control of the morphology of β-NaYF4:Yb,Er/Tm upconversion nanophosphors (UCNPs) from large spheres (37.9 nm) to rods (length = 60.1 nm, width = 21.5 nm) and from rods to hexagonal prisms (length = 48.8 nm, width = 44.0 nm) or small spheres (14.0 nm) by the use of a surfactant, an additive, and lanthanide doping. Increasing the ratio of oleic acid (OA) to 1-octadecene (ODE) caused a decrease in the size of the UCNPs, and increasing the OA/ODE ratio above a critical value caused the particle shape to change from a sphere to a rod. The length-to-width aspect ratio (AR) of upconversion nanorods (UCNRs) was finely manipulated from 1.28 to 2.80. The rounded tips of the UCNRs were flattened by adding Cl(-) ions, and the UCNRs changed to hexagonal prisms with a controllable AR depending on the quantity of Cl(-) ions. Additionally, the morphology of the β-NaYF4-based UCNPs was controlled by lanthanide doping. The size and AR of the UCNRs decreased with Gd(3+) doping, and the UCNRs ultimately transformed into small spheres (14.0 nm) with high monodispersity. Doping with Ce(3+) ions also decreased the AR of the UCNRs from 2.80 to 1.27. In addition, highly transparent polymer composites for 3D volumetric displays were fabricated by blending high-AR β-NaYF4:Yb,Er/Tm UCNRs with polydimethylsiloxane. These composites exhibited bright green and blue upconversion light during excitation with 980 nm light.

Synthesis and Properties of a Diazopentacene Analogue

We report the synthesis, optical, and electrochemical properties, as well as the organic light-emitting diode (OLED) performance of diazopentacene 2,7,11,16-tetra-tert-butyldiphenanthro[4,5-abc:4′,5′-hij]phenazine (BDPP, 1). BDPP has two absorption peaks centered at 350 nm and 460 nm with a shoulder peak at 434 nm and fluoresces bright green light with the emission peak at 481 nm when excited at 360 nm in dichloromethane solution. Interestingly, the UV absorption of BDPP is sensitive to different Lewis acids and organic acids. Calculations revealed that the theoretical band gap is 2.83 eV, which is close to experimental optical data (2.69 eV). Furthermore, OLEDs that use BDPP as the emitter were fabricated. The results indicate that BDPP derivatives might be a good candidate to enhance the efficiency of OLEDs.

Synthesis of silica protected photoluminescence QDs and their applications for transparent fluorescent films with enhanced photochemical stability

In this paper, we have demonstrated a novel and simple way to prepare transparent composite fluorescent films by using poly (acrylic acid) co-polymer as a matrix and silica coated photoluminescence (PL) quantum dots (QDs) as light-emitting materials. The strategies include preparing aqueous amphiphilic oligomer (polymaleic acid n-hexadecanol ester, PMAH) modified QDs, encapsulating the aqueous QDs in silica with a modified Stöber method and fabricating the QD–PMAH–SiO2–polymer composite fluorescent films with a spin-coating method. The obtained light-emitting thin films were transparent under room light and showed bright red, green and deep-blue light under the irradiation of UV light. The PL intensity of the composite films increased incrementally with the number of layers and the concentration of QD–PMAH–SiO2 within each film. A white light emitting film was also fabricated by combining the silica coated red, green and deep-blue QDs in a proper ratio. Moreover, the photochemical stability of the QD–PMAH–SiO2 in composite film was enhanced significantly compared with PMAH coated QDs, because of a thicker and compact passivating silica layer formed on the surfaces of the PL QDs.

Bright dual-mode green emission from selective set of dopant ions in β-Na(Y,Gd)F4:Yb,Er/β-NaGdF4:Ce,Tb core/shell nanocrystals

Bright dual-mode green-emitting core/shell nanoparticles (NPs) were synthesized by doping selective set of lanthanide ions. Up-conversion (UC) green-emitting β-NaY0.2Gd0.6F4:Yb0.18,Er0.02 NPs (8.3 nm) were used as core material. Bright down-conversion (DC) green-emitting β-NaGd0.8F4:Ce0.15,Tb0.05 NPs showed ca. 31 times higher photoluminescence (PL) intensity than β-NaGdF4:Tb NPs and they were served as shell material with their excellent PL properties. The UC/DC core/shell NPs showed bright green light under excitations of 980 nm near infrared (NIR) light and 254 nm ultraviolet (UV) light, respectively. The UC/DC core/shell NPs showed ca. 11 times higher UC PL intensity than core UCNPs. Consequently, the core/shell NPs doped with selective set of lanthanide ions showed bright dual-mode green emission under excitations of NIR light and UV light, indicating that they are promising for application to optical imaging.

Novel lanthanide hybrid functional materials for high performance luminescence application: The relationship between structures and photophysical behaviors

Functional luminescent hybrid materials have emerged as fascinating and promising materials for their versatile applications. In this report, novel efficient luminescent lanthanide (Tb3+, Eu3+) hybrid materials with a new kind of amide-type β-diketone ligands covalently bonded to the silica gels have been assembled through the sol–gel progresses. The hybrid materials have been characterized by the Fourier transform infrared (FTIR) spectra, UV–vis absorption spectra, powder X-ray diffraction (PXRD), scanning electron microscope (SEM), and thermal analyses. The relationship between structures and photophysical behaviors of these materials was discussed in detail. The materials assembled by the precursors containing aromatic end group (Si–L1–Ln) exhibited longer luminescence lifetimes and higher quantum efficiencies, suggesting that the existence of a suitable conjugated system should allow a more efficient energy transfer. Under UV irradiation, the materials emitted either bright green light or red light with different intensity which may lead to potential functional applications in optical devices and electronic devices.

Hydrothermal synthesis of β-NaYF4 nanotubes by in situ ion exchange reaction using Y(OH)3 nanotubes as templates

In this article, we reported the synthesis of uniform hexagonal NaYF4 (β-NaYF4) nanotubes through in situ ion exchange reaction using Y(OH)3 nanotubes as templates via a facile hydrothermal route. The structure and morphology of the products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the as-prepared β-NaYF4 with a length of about 4μm, an external diameter of about 160nm, and a thickness of about 50nm preserved the basic morphology of the initial Y(OH)3 nanotubes. The influence of pH value of the precursor on the morphology and structure of the products was also studied, and the results indicated that β-NaYF4 nanotubes could only be obtained at proper pH value. The strength of acids adjusting the pH value of the precursor had no influence on the morphology and structure of the products. Additionally, the upconversion luminescence properties of Yb3+/Er3+ codoped β-NaYF4 were investigated. Yb3+/Er3+ codoped NaYF4 emitted bright green and red light, both of which were two-photon processes.