Commission Internationale De I ' Eclairage Research Articles

Facile synthesis, novel structure, and tunable luminescence properties of K6Bi13(PO4)15:Dy3+,Eu3+ phosphors for ultraviolet converted white light-emitting diodes

A variety of novel Dy3+/Eu3+ mono- and co-doped K6Bi13(PO4)15 (KBPO) luminescent materials have been fabricated by a simple solid-state method for the first time. Both experimental studies and theoretical calculations verify that the K6Bi13(PO4)15 crystals are suitable to be utilized as host materials for the lanthanide activator ions. The XRD, EDS, and XPS results reveal that the Dy3+ and Eu3+ have been effectively incorporated into the KBPO host matrix and do not damage the structure of KBPO. The Dy3+ or Eu3+ mono-doped phosphors display the characteristic spectral patterns of the activator ions upon UV excitation whereas an energy transfer between Dy3+ and Eu3+ occurs which helps to obtain the tunable luminescence of the KBPO:Dy3+,Eu3+ phosphors. The emission colors of the KBPO:Dy3+,Eu3+ regularly shift from green-blue, through white, and finally toward yellow and orange-red by varying the activator doping concentrations under a fixed excitation wavelength. Interestingly, the single-phase white light emitting phosphors with CIE chromaticity coordinates of (0.3122, 0.3106) and (0.3602, 0.3246) are obtained by doping appropriate concentrations of Dy3+ and Eu3+, which match well with the standard white light illuminate of (0.333, 0.333). Moreover, the annealing conditions are optimized and the luminescent mechanisms and temperature-dependent luminescence performance are systematically investigated. Finally, the WLEDs device prepared by KBPO:Dy3+,Eu3+ phosphor and UV chip displays a dazzling white light with favorable CIE (Commission Internationale de I'Eclairage 1931 chromaticity) coordinates, color rendering index (Ra), correlated color temperature (CCT), and thermal stability, which provides direct evidence that the as-prepared inorganic luminescent materials may have prospects as an eminent single-phase white light emitting materials for white light-emitting diodes (WLEDs) and optoelectronic devices.

Julolidine-hydrazone based chemosensor for detection of Zn2+: Fluorescent in-situ formed Zn2+ complex discriminates PPi from ADP and ATP

In the present investigation, we have designed and synthesised Zn2+ sensitive Julolidine-hydrazone (JSB) based chemosensor, which crystallised in a monoclinic crystal system with P21/c space group. The bare JSB was nonemissive, but in the presence of Zn2+ ions in solution it showed emission, ascribed to the chelation enhanced emission process, which is also utilised to detect Zn2+ in water samples. Comparing the chromaticity coordinates deduced from the emission colors of the JSB-Zn2+ in solution, powder and hybrid polymer thin film, using CIE (Commission Internationale de I'Eclairage 1931) chromaticity diagram, it was found that compared to the emission of the solution, the emission of the powder was red shifted, while that of the thin film was blue shifted. Further, the sensing of Zn2+ showed reversibility in the presence of pyrophosphate (PPi), which allowed quantification of PPi. Interestingly, in addition to the detection of PPi using the in-situ formed JSB-Zn2+ complex, the process was selective and discriminated PPi from ADP and ATP. The detection of PPi was rationalized via a decomplexation reaction, and translated in the construction of INHIBIT logic gate. Additionally, the possible use of the JSB coated sensor paper for the on-site detection of Zn2+ and subsequent JSB-Zn2+ complex for PPi ions has been demonstrated. The experimental results showed good correlation with the theoretical calculations wherever possible.

Efficient Green Phosphorescent Organic Light Emitting Diode using Iridium Complex

We report here the fabrication and characterization of an efficient green phosphorescent organic light emitting diodes (PhOLED) using phosphorescent iridium complex, tris(2-phenylpyridine) iridium (III) (Ir(ppy)3). Ir(ppy)3 is an organic phosphorescent material, which emits green light via both the singlet as well as triplet exciton relaxation. To avoid triplettriplet annihilation and for efficient light emission, the phosphorescent emitters should be doped in a suitable host material which has band-gap larger than the doped guest material and the band gap of the guest should lie within the band-gap of the host. We optimally doped phosphorescent Ir(ppy)3 into a fluorescent 4,4'-bis(9-carbazolyl) biphenyl (CBP) host and used it as the emitter to prepare PhOLEDs. The PhOLED exhibited green electroluminescence (EL) in the range ~ 480-650 nm with EL peak at 550 nm along with a shoulder at 510 nm. The Commission Internationale de-I’eclairage (CIE) colour coordinate of the device was measured to be (0.25, 0.60). The current density vs voltage vs luminescence (J-V-L) characteristics of the device led us to calculate its current efficiency, which was found to be 28.9 cd/A at 7V. The efficiency of PhOLED decreased with increment in the applied voltage beyond 7 V and has been attributed to the triplet-triplet annihilation due to high injected current densities.

A novel erbium material with a fascinated mercury bromide cluster (Hg11Br34)12– anion: synthesis and characterization

A novel erbium material with a fascinated mercury bromide cluster (Hg11Br34)12– anion, i.e., {[Er2(H2O)4(HIA)6]2n}(nHg11Br34)(nHgBr2)·4nH2O (denoted as 1 and HIA indicates the isonicotinic acid molecule), was successfully synthesized from a solvothermal reactor. Its single crystal structure was determined by single-crystal and powder X-ray diffractions. The Er3+ ions have a distorted square antiprism motif, and they are connected by isonicotinic acid molecules to yield a one-dimensional (1-D) chain. The Hg2+ ions show two or four coordination motifs. This compound contains an unprecedented mercury bromide cluster (Hg11Br34)12– anion. This compound shows upconversion green photoluminescence emission with a CIE (Commission Internationale de I'Eclairage) chromaticity coordinates at (0.1749, 0.4351). It has a wide band gap of 3.24 eV. A novel erbium material with a fascinated mercury bromide cluster (Hg11Br34)12– anion was reported. The Er3+ ions have a distorted square antiprism motif and the compound features a 1-D chain-like structure. The Hg2+ ions show two or four coordination motifs. It features upconversion green emission with CIE coordinates 0.1749 and 0.4351. It has a wide band gap of 3.24 eV.

Fabrication and opto-electronic analysis of down-converting blue-green emitting nanophosphor

A series of nano-scaled Tb3+-doped Ba3Y(PO4)3 (BYPO) nanophosphors were successfully fabricated utilizing a time-saving solution-combustion approach. The crystal structure and lattice parameters of the Ba3Y0.93Tb0.07(PO4)3 nanophosphor was examined by Reitveld refinement analysis. The incorporation of trivalent terbium ions into the cubic crystal lattice (I − 4 3 d (220) space group) did not bring any change in the crystal prototype. The photoluminescence (PL) result showed that the blue-to-green tunable emission can be achieved simply via varying the dopant concentration, with 7 mol% as the optimum concentration for standard CIE (Commission Internationale de I’Eclairage) coordinates of green emission. A comprehensive examination of PL-decay curves using Auzel’s model gives the intrinsic radiative lifetime (3.9585 ms) for the 5D4 state in Tb3+. The CIE coordinates values illustrate the blue region at lower concentrations and the green region at higher concentrations of the terbium ions, signifying the color-tunability in the system. The outcomes specify that this nanophosphor is a relevant candidate for phosphor converted white LEDs (PC-WLEDs) using near ultraviolet (UV) excitation.

Synthesis, Characterization, Properties, and Theoretical Calculation of an Inorganic–Organic Hybrid Mononuclear Copper(II) Complex Containing 3-Hydroxy-2-methyl-quinoline-4-carboxylate

A novel copper complex [CuL(bipy)(H2O)]·H2O was synthesized by solvothermal reaction and its crystal structure was determined by single-crystal X-ray diffraction technique. (HL = 3-hydroxy-2-methylquinoline4-carboxylic acid; bipy = 2,2′-bipyrdine) The title complex (1) crystallizes in the orthorhombic system of the Pbca space group, and exists as an isolated mononuclear structure. The intermolecular hydrogen bonds and the strong π···π stacking interactions yield a three-dimensional (3-D) supramolecular network. Solid-state photoluminescence spectrum uncovers that it shows an emission in the pale blue region of the light spectrum. It has remarkable CIE (Commission Internationale de I’Eclairage) chromaticity coordinates of (0.2656, 0.3162), so it may be a very promising color lighting and display converter. Time-dependent density functional theory (TDDFT) calculation reveals that this emission is caused by to the ligand-to-ligand charge transfer (LLCT). Solid-state diffuse reflectance data shows that there is a narrow optical band gap of 1.38 eV. Therefore, it could be probably a candidate for narrow band gap semiconductors. A novel copper (II) complex is synthesized via solvothermal reactions, which is characteristic of an isolated structure, at the same time, it displays a wide and intense photoluminescence emission band in the pale blue region and theoretical study reveals that the photoluminescence emission is originated from the ligand-to-ligand charge transfer transition.

Crystal structure, synthesis and photoluminescent properties of a reddish-orange light emitting SrGdAlO4: Sm3+ nanophosphor

A series of reddish orange light emitting SrGdAlO4: Sm3+ nanophosphor was prepared by urea aided solution combustion process. Structural features of the prepared nanophosphor were described by the powder X-ray diffraction (PXRD) together with Rietveld refinement technique. The results authenticate the existence of single phased tetragonal lattice with space group of I4/mmm (139). The highly intense peak observed in the photoluminescence emission spectra of the synthesized nanocrystalline phosphors was observed at 600 nm owing to 4G5/2 → 6H7/2 transition upon excitation by 407 nm light. The estimated energy band gap of SrGd0.97Sm0.03AlO4 nanophosphor was found to be 5.45 eV. The critical distance value evaluated for non-radiative energy transfer comes around 17.52 Å. The main reason responsible for the observed concentration quenching phenomenon in emission intensity of the prepared nanophosphor beyond 3 mol % doping of Sm3+ was found to be dipole-dipole (d-d) type electric multipolar interaction. The refractive index of the optimized nanophosphor (SrGd0.97Sm0.03AlO4) comes around 1.682. The chromaticity coordinates were found to lie in the reddish-orange region of CIE (Commission Internationale De I'Eclairage) diagram. The vivid description of the photoluminescent and structural aspects validate the potential applications of synthesized nanophosphor as optical nanomaterials in phosphor converted white light emitting diodes (pc-WLEDs).

Combustion synthesis, Judd–Ofelt parameters and optical properties of color tunable Ba3Y4O9: Eu3+ nanophosphor for near-UV based WLEDs

Solution combustion synthesis, a simple and efficient route was adopted to synthesize color tunable Ba3Y4O9: Eu3+ nanophosphor with varying composition of trivalent europium ions. Structural analysis using powder X-ray diffraction technique reveals trigonal crystal system belonging to hexagonal crystal family with R3 (143) space group and nanocrystalline nature of the synthesized phosphor. The average size of the synthesized phosphor in nano-scale range was confirmed by using Scherrer’s equation and transmission electron microscope (TEM) analysis. A structure refinement technique i.e. Rietveld refinement was employed over powder X-ray diffraction data that fits the entire powder pattern together with peak shapes and background. Photoluminescent features were analyzed via recording excitation (200–500 nm), emission profile (415–750 nm) and luminescence decay curves for optoelectronic applications. The emission spectrum shows characteristic intense peak at 615 nm by means of 5D0 → 7F2 electric dipole transition. Judd–Ofelt parameters for all concentration of Eu3+ doped system were determined by employing Judd–Ofelt theory. The optimum doping concentration of Eu3+ ions in Ba3Y4(1−x)O9: 4x Eu3+ was found to be x = 0.10. Moreover, the critical distance was computed to be 10.91 A suggesting d–d interactions as a major reason for concentration quenching phenomenon. The energy band gap values for pure host lattice and optimized system were calculated as 5.41 eV and 5.91 eV respectively via Kubelka–Munk theory. CIE (Commission Internationale De I’eclairage) color coordinates lie in blue–white–red region depending upon the composition of dopant ion. The potential use of synthesized nanophosphor as a warm light source was evident from the correlated color temperature (CCT) result.

Synthesis and characterization of undoped and Fe(III) ions doped NaCaAlPO4F3 phosphor

Undoped and Fe(III) ions doped NaCaAlPO4F3 phosphor has been synthesized using solid state reaction method. The prepared phosphor material was characterized by powder X-ray diffraction (XRD), SEM with EDS, optical absorption, photoluminescence (PL), electron paramagnetic resonance (EPR) and FT-IR techniques. The average crystallite size was calculated from powder XRD data. SEM micrographs show the presence of several irregular shaped particles. Optical absorption spectrum exhibited the characteristic absorption bands of Fe(III) ions in distorted octahedral site symmetry. EPR spectrum exhibited two resonance signals at g=4.25 and g=2.00. PL spectrums of both undoped phosphor exhibits emission peaks at 407, 413 and 469nm and Fe(III) ions doped phosphor gave the emission peaks at 373 and 450nm under UV excitation. The Commission Internationale deI'Eclairage (CIE) chromaticity coordinates for undoped and Fe(III) ions doped NaCaAlPO4F3 phosphor material are calculated from the emission spectrum. Vibrational bands related to phosphate molecules, P–O–H and hydroxyl ions are observed in the FT-IR spectrum.

Color Measurement and Color Spaces Analysis for TV Using the (Commission International D’Éclairage) CIE System Evaluation

Color is a perceived phenomenon and not a physical dimension like length ortemperature, although the electromagnetic radiation of the visible wavelength spectrum is measurable as a physical quantity. A suitable form of representation must be found for storing, displaying, and processing color images. This representation must be well suited to the mathematical demands of a color image processing algorithm, to the technical conditions of a camera, printer, or television, and to human color perception as well. These various demands cannot be met equally well simultaneously. For this reason, differing representations are used in color image processing according to the processing goal. Color spaces indicate color coordinate systems in which the image values of a color image are represented. The standard color system, established by the International Lighting Commission CIE (Commission Internationale de I ’Eclairage), will be described. This system represents the international reference system of color measurement. The contribution deals with the Matlab application used for television and color spaces analysis. All of the color spaces can be derived from the RGB information supplied by devices such as cameras and scanners. There is a list of common color spaces. The application allows selection of input color image, direct and backward transformation into the selected space including CIE diagram picture analysis and NTSC system. The additional functions of this research are evaluation of histogram of colors. The Color Spaces application outputs are introduced on various test pictures.

토너입자형 디스플레이의 평가방법 제안

A measurement method of the particle-based reflective display is proposed, estimated, and compared with reported method. The reflectivity measurement by previous studies is simply obtained by integrating sphere, but it has a limitation for the estimation of real moving particles because its data include surface reflection and incomplete attachment on electrodes. To get the number of real moving particles, the area by attached particles on the electrodes is calculated at microscopic signals. The moving particles on subthreshold voltage are observed and this fluctuational variation of surface on subthreshold voltage gives a tip to understand the driving mechanism. By this measurement we ascertained the relationship of a particle layer and real driving particles, and the feasibility of observation and estimation for moving color particles, which were measured by the reflectivity and CIE (Commission Internationale de I'Eclairage) system of color specification at previous studies.

High Efficiency Red Phosphorescent Organic Light Emitting Diodes with Emission Structure of (TCTA/TCTA0.5TPBi0.5/TPBi):(pq)2Ir(acac)

Based on the emission structure of (TCTA/TCTA0.5TPBi0.5/TPBi) doped with 10% (pq)2Ir(acac) [hereafter, (TCTA/TCTA0.5TPBi0.5/TPBi):(pq)2Ir(acac)], new red phosphorescent organic light emitting diodes with different host structures in thickness were fabricated and evaluated. Among the devices with various thicknesses of TCTA in a range of 50 Å ∼ 150 Å in the limits of 100 Å-thick TCTA0.5TPBi0.5 and 300 Å-thick total host, the best electroluminescent characteristics was obtained in the device with emission structure of [TCTA (80 Å)/TCTA0.5TPBi0.5 (100 Å)/TPBi (120 Å)]:(pq)2Ir(acac). In this device, current density, luminance, and current efficiency were found to be 98 mA/cm2, 15,800 cd/m2, and 16 cd/A at an applied voltage of 9 V, respectively. The maximum current efficiency was 24.5 cd/A under a luminance of 50 cd/m2. The peak wavelength in the electroluminescence spectral distribution was 606 nm. The color coordinates were (0.62, 0.37) on the CIE (Commission Internationale de I'Eclairage) chart.

High Efficiency Green Phosphorescent Organic Light Emitting Devicesusing the Emission Layer of (TCTA/TCTA₁/₃TAZ₂/₃/TAZ):Ir(ppy)₃

We have fabricated and evaluated newNew high high-efficiency green green-light light-emitting phosphorescent devices with an emission layer of [<TEX>$TCTA/TCTA_{1/3}TAZ_{2/3}/TAZ$</TEX>] : <TEX>$Ir(ppy)_3$</TEX> were fabricated and evaluated, and compared the electroluminescence characteristics of these devices were compared with the conventional phosphorescent devices with emission layers of (<TEX>$TCTA_{1/3}TAZ_{2/3}$</TEX>) : <TEX>$Ir(ppy)_3$</TEX> and (TCTA/TAZ) : <TEX>$Ir(ppy)_3$</TEX>. The current density, luminance, and current efficiency of the a device with an emission layer of (<TEX>$80{\AA}-TCTA/90^{\circ}{\AA}-TCTA_{1/3}TAZ_{2/3}/130{\AA}-TAZ$</TEX>) : 10%-<TEX>$Ir(ppy)_3$</TEX> were <TEX>$95\;mA/cm^2$</TEX>, <TEX>$25000\;cd/m^2$</TEX>, and 27 cd/A at an applied voltage of 10 V, respectively. The maximum current efficiency was 52 cd/A under the a luminance value of <TEX>$400\;cd/m^2$</TEX>. The peak wavelength and FWHM (FWHM (full width at half maximum) in the electroluminescence spectral were 513 nm and 65 nm, respectively. The color coordinate was (0.30, 0.62) on the CIE (Commission Internationale de I'Eclairage) chart. Under the a luminance of <TEX>$15000\;cd/m^2$</TEX>, the current efficiency of the a device with an emission layer of (<TEX>$80{\AA}-TCTA/90{\AA}-TCTA_{1/3}TAZ_{2/3}/130{\AA}-TAZ$</TEX>) : 10%-<TEX>$Ir(ppy)_3$</TEX> was 34 cd/A, which has beenshowed an improvement of improved 1.7 and 1.4 times compared to those of the devices with emission layers of (<TEX>$300{\AA}-TCTA_{1/3}TAZ_{2/3}$</TEX>) : 10%-<TEX>$Ir(ppy)_3$</TEX> and (<TEX>$100{\AA}-TCTA/200{\AA}$</TEX>-TAZ) : 10%-<TEX>$Ir(ppy)_3$</TEX>, respectively.

Enhanced white light emission fromGdAl3(BO3)4:Dy3+,Ce3+ nanorods

GdAl3(BO3)4 nanorods doped with rare-earth ions have been obtained via a combustion synthesis. Thenanorods have been characterized by x-ray diffraction, micro-Raman spectra, variousmicroscopy techniques and fluorescence measurements. The results show that the nanorodsare of straight morphology and smooth surface with an average diameter of 60 nm. TheGdAl3(BO3)4:Dy3+ nanorods show intense emissions centred at 480, 575, and 665 nm upon excitation byboth ultraviolet-blue and infrared light, which are associated with the typicaltransitions of , and of Dy3+, respectively.The presence of Ce3+ in the nanorods resulted in an enhancement of theDy3+ emission intensityby a factor of ∼2. Furthermore, the values of yellow-to-blue integral intensity of the nanorods decrease rapidly with anincrease of Ce3+ concentration, which indicates that the emitted light approaches the CommissionInternationale de I’Eclairage (CIE) ideal white conditions.

Preparation and Characterization of Spinel MCr&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; (M = Zn, Co, Cu and Ni) by Combustion Reaction

Preparation and Characterization of Spinel MCr&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; (M = Zn, Co, Cu and Ni) by Combustion Reaction

260 Blocking effects of promethazine triprolidine and their analogues on the excitation caused by the peptide, achatin-I

A series of nano-scaled Tb3+-doped Ba3Y(PO4)3 (BYPO) nanophosphors were successfully fabricated utilizing a time-saving solution-combustion approach. The crystal structure and lattice parameters of the Ba3Y0.93Tb0.07(PO4)3 nanophosphor was examined by Reitveld refinement analysis. The incorporation of trivalent terbium ions into the cubic crystal lattice (I − 4 3 d (220) space group) did not bring any change in the crystal prototype. The photoluminescence (PL) result showed that the blue-to-green tunable emission can be achieved simply via varying the dopant concentration, with 7 mol% as the optimum concentration for standard CIE (Commission Internationale de I’Eclairage) coordinates of green emission. A comprehensive examination of PL-decay curves using Auzel’s model gives the intrinsic radiative lifetime (3.9585 ms) for the 5D4 state in Tb3+. The CIE coordinates values illustrate the blue region at lower concentrations and the green region at higher concentrations of the terbium ions, signifying the color-tunability in the system. The outcomes specify that this nanophosphor is a relevant candidate for phosphor converted white LEDs (PC-WLEDs) using near ultraviolet (UV) excitation.