Luminescent Display Research Articles

Living in sympatry via differentiation in time, space and display characters of courtship behaviors of bioluminescent marine ostracods

Distinguishing among courtship signals can be extremely important for individuals in regions where related species co-occur, including among sympatric species pairs and along hybrid zones. Reef habitats off the coast of Belize are shared by bioluminescent ostracods that perform nightly bioluminescent displays used in courtship. These displays vary in light pulse durations, interpulse distances and intervals, and direction. Here, we test how six sympatric species of marine ostracods (three described and three undescribed species) partition the display arena in time and space. Males from all six species can be differentiated based on morphology and species-specific luminescent display traits. Timing of nightly courtship display initiation and peak display timing differed among species by 5–25 min, and the order of appearance for each species was consistent across nights. In addition to varying temporally, species used different microhabitats (grassbed, sand channels, reef slopes and reef crest) for their courtship displays. Our findings support the hypothesis that species with more similar display traits (pulse duration, interpulse distance, number of pulses) differ most in the time and space used for courtship. The large number of axes for displacement of both luminescent display traits and spatio-temporal habitat use for courtship suggests that ostracods have the genetic toolkit for rapid diversification. This species complex living in sympatry yields a rich system for testing how genetic determination of behavioral traits relates to sexual selection and speciation.

Prediction of color characteristics of luminescent video display based on fluorescent polyolefin films containing CdSe/CdS/ZnS quantum Dots

This paper is devoted to a consideration of the possibility to predict the color characteristics of a luminescent video display based on fluorescent polyolefin films containing CdSe/CdS/ZnS quantum dots. It is shown that the use of new colloid semiconductor materials based on CdSe/CdS/ZnS opens up wide prospects for the development of a new generation of luminescent video displays. New methods are developed and existing ones are adapted for the calculation and prediction of the color gamut of luminescent and liquid-crystal (LC)monitors.

Energy transfer based photoluminescence properties of (Sm3+ + Eu3+):PEO + PVP polymer films for Red luminescent display device applications

Eu3+:PEO+PVP, Sm3+:PEO+PVP and co-doped Sm3++Eu3+:PEO+PVP polymer films have successfully been synthesized by solution casting method. For these polymer films, their XRD, FTIR and RAMAN spectral profiles were studied systematically. Both absorption and photoluminescence spectra have been assessed by evaluating their optical properties. The Sm3+:PEO+PVP and Eu3+:PEO+PVP polymer film has displayed a reddish-orange and red emissions at 596nm and 619nm respectively under an UV lamp. A reddish-orange emission was found for Sm3+:PEO+PVP polymer film at 596nm (4G5/2→6H7/2) and its lifetime has also been evaluated suitably. Red emission at 619nm (4G5/2→6H7/2) of Eu3+ has been identified for Eu3+:PEO+PVP polymer film and its lifetime are also evaluated. The photoluminescence efficiency of Eu3+ ion has been enhanced due to the addition of Sm3+ by means of an energy transfer process. The energy transfer mechanism, from Sm3+ to Eu3+ has been clearly established. At 0.1wt% concentration of Sm3+ ions (sensitizer), the photoluminescence efficiency of the Eu3+ ion (activator) has been significantly enhanced in co-doped sample through energy transfer from Sm3+ to Eu3+ in the polymer matrix. The energy transfer process has been analyzed using lifetime decay dynamics. From the obtained results, these polymer materials could be proposed as potential Red luminescent optical materials.

Dy3+-doped tellurite based tungsten-zirconium glasses: Spectroscopic study

Tellurite based tungsten zirconium glasses-doped with trivalent dysprosium (Dy3+) ions (TWZDy) have been prepared by conventional melt-quenching technique and characterized through thermal, structural and spectroscopic measurements. XRD pattern of the glass confirms its amorphous nature. The functional groups of the TeO3 and TeO4 units along with WO− and ZrO vibrations have been identified from Fourier transform infrared spectrum. The energy level analysis has been carried out by using the parametric free-ion Hamiltonian model. Judd–Ofelt theory has been used to explore the spectral intensities of Dy3+ ions in the present glass system. From the emission spectra, the emission intensities increases from 0.05 to 1.0mol% of Dy3+ ion and then decreases for higher concentrations due to energy transfer between Dy3+ ions. The higher value of peak stimulated emission cross-section (40.46×10−22cm2), noticed for 4F9/2→6H13/2 transition, is comparable with other reported Dy3+ systems. The TWZDy glasses emit intense yellowish-white color (x=0.32; y=0.44) which is nearer to standard white light zone. The decay curves exhibit single exponential nature at lower concentrations (⩽0.1mol%) and turns into non-exponential (⩾0.5mol%) due to energy transfer processes. In order to unravel the energy transfer process the non-exponential decay curves have been fitted to Inokuti–Hirayama (IH) model with S=6. The analyses of the results indicate that the present TWZDy glasses are suitable for luminescent display device applications as well as for white light generation.

Synthesis of Sm3+ and Dy3+ doped LaBWO6 for evaluation as potential materials in luminescent display applications

A series of Sm3+ and Dy3+ doped LaBWO6 phosphors were synthesized by high temperature solid state reaction. Recorded XRD patterns proved that the titled compound in a single phase has been obtained. Sm3+ and Dy3+ doped LaBWO6 could emit orange and white light, respectively. The optimal doping concentration of Sm3+ or Dy3+ was experimentally ascertained to be 6mol%. The critical distance of energy transfer for Sm3+ or Dy3+ doped sample is 1.540nm. In addition, there is no cross energy transfer between the Sm3+ and Dy3+ ions in the co-doped samples. The results indicated that the electric dipole–dipole interaction is predominant energy transfer mechanism for concentration quenching of Sm3+ or Dy3+ doped LaBWO6 phosphor. The charge transfer band was observed in the excitation spectra of Sm3+ or Dy3+ doped LaBWO6 phosphors. Present investigation indicated that Sm3+ and Dy3+ doped LaBWO6 can be applied in solid state lighting and LaBWO6 is a promising host for display applications.

Luminescent investigations of Li6Lu(BO3)3:Tb3+, Dy3+ phosphors

In our novel work we report the luminescence properties of Terbium (Tb3+) and Dysprosium (Dy3+) ions in Li6Lu(BO3)3 (lithium lutetium borate) phosphors with its specific and productive use in various luminescent display systems. We have synthesized Tb3+ and Dy3+ doped Li6Lu(BO3)3 phosphors by the solid state reaction method. Concentration based optimization of activators is attained i.e. 2mol% for Tb3+ and 5mol% for Dy3+. XRD (X-ray diffraction) and FE-SEM (Field emission-scanning electron microscopy) were used to analyze the overall morphologies, crystalline structures and the grain sizes of the prepared phosphors. Moreover, the grain size of 20μm is confirmed via Scherrer’s formula. In order to characterize the luminescence properties of the synthesized phosphors, we measured its X-ray induced luminescence, proton induced luminescence and UV induced photoluminescence. Under UV luminescence Dy3+ doped phosphor, it displayed seven obvious peaks corresponding to transitions from 6H15/2 (f9) ground state to higher energy state of 4f9 whereas, UV-emission spectrum of Li6Lu(BO3)3:Tb3+ phosphor has shown five major transitions with each peak consists of several smaller lines, confirming the complicated transition (5Dj→7Fj) behavior of Tb3+. The light yield calculated for Li6Lu(BO3)3:Tb3+ is 75% that of (Y,Gd)2O3:Eu3+ phosphor which is a well known commercially available material for PDP (Plasma Display Panel). It is observed that due to the presence of Lutetium, the synthesized phosphor has high effective atomic number (Zeff=52) as well as high molecular weight (M.Wt=393g/mol) which makes lithium lutetium borate one of the promising candidates for X-ray imaging in medical field. Furthermore, the presence of 6Li and 10B could make Li6Lu(BO3)3 phosphor as a potential neutron detector.

Synthesis of Bi3+ and Gd3+ doped ZnB2O4 for evaluation as potential materials in luminescent display applications

A series of Bi3+ and Gd3+ doped ZnB2O4 phosphors were synthesized with solid state reaction technique. X-ray diffraction technique was employed to study the structure of prepared samples. Excitation and emission spectra were recorded to investigate the luminescence properties of phosphors. The doping of Bi3+ or Gd3+ with a small amount (no more than 3mol%) does not change the structure of prepared samples remarkably. Bi3+ in ZnB2O4 can emit intense broad-band purplish blue light peaking at 428nm under the excitation of a broad-band peaking at 329nm. The optimal doping concentration of Bi3+ is experimentally ascertained to be 0.5mol%. The decay time of Bi3+ in ZnB2O4 changes from 0.88 to 1.69ms. Gd3+ in ZnB2O4 can be excited with 254nm ultraviolet light and yield intense 312nm emission. The optimal doping concentration of Gd3+ is experimentally ascertained to be 5mol%. The decay time of Gd3+ in ZnB2O4 changes from 0.42 to 1.36ms.

Non-Enzymatic-Browning-Reaction: A Versatile Route for Production of Nitrogen-Doped Carbon Dots with Tunable Multicolor Luminescent Display

The non-enzymatic browning, namely Maillard reaction is commonly invoked to account for abiotic chemical transformations of organic matter. Here we report a new reaction pathway via the Maillard reaction to systematically synthesize a series of nitrogen-doped carbon dots (C-dots) with superhigh quantum yield (QY) and tunable multicolor luminescent displayment. The starting materials are glucose and the serial amino acid analogues which allow systemically controlling luminescent and physicochemical properties of C-dots at will. Unexpectedly, the as-prepared C-dots possess bright photoluminescence with QY up to 69.1% which is almost the highest ever reported, favorable biocompatibility, excellent aqueous and nonaqueous dispersibility, ultrahigh photostability, and readily functionalization. We have demonstrated that they are particularly suitable for multicolor luminescent display and long-term and real-time cellular imaging. Furthermore, the methodology is readily scalable to large yield, and can provide sufficient amount of C-dots for practical demands.

Light-recycling within electronic displays using deep red and near infrared photoluminescent polarizers

We report a linearly polarized luminescent solar concentrator with broad absorption across the visible, and luminescence beyond the emissive spectrum of the display. When used to replace a conventional polarizer in a luminescent display, this device recycles light absorbed by the polarizer, guiding it to the frame of the display where solar cells may be mounted.

Optical Properties of CdS–PVA Nanocomposites

Semiconductor–polymer nanocomposites, with good control over the nanoparticle size and their dispersion within the polymer matrix, can have applications in many optical and luminescent display devices. Cadmium sulphide (CdS) is the most popular semiconductor nanoparticle exhibiting size dependent properties due to its large exciton binding energy and its suitability for large scale production. The nanoparticles need to be passivated against aggregation with suitable capping agents, without sacrificing the desirable properties like transparency and flexibility of the polymer. Cadmium sulphide nanoparticles capped with polyvinyl pyrrolidone (PVP) are synthesized using cadmium nitrate (Cd(NO3)2) and hydrogen sulphide (H2S) as Cd2+ and S2– sources, respectively. CdS particles with sizes in the range of 5–6 nm are prepared in methanol and the solvent is removed using a rotary evaporator. CdS powder is dispersed in polyvinyl alcohol (PVA) solution with dimethyl formamide (DMF) as solvent to get (PVP–CdS)–PVA nanocomposite film of about 0.2 mm thickness. This has been characterized by powder X-ray diffraction (XRD), optical absorption studies, transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and photoluminescence (PL). Particle size does not change due to incorporation in the polymer matrix and the polymer retains its transparency and flexibility. The nanocomposite shows good photoluminescence property with stronger band edge emission than defect related emission. The latter could be quenched completely by optimizing the PVP content. Irradiation of the nanocomposite with 8 MeV electrons at a dose of 100 kGy could effectively quench the defect related emission.

Complex sexual courtship displays by luminescent male marine ostracods

In the western Caribbean Sea, about an hour after the sun sets, a complex and ritualized light show of precise, vertically placed luminescent pulses erupts over shallow grassbeds. These are among the most complex displays known in marine systems. Displays consist of repeated trains of secreted bioluminescent pulses in a specific pattern ejected into the water column as courtship signals by male Vargula annecohenae, which are small (<2 mm) myodocopid ostracod crustaceans. Although these animals display in near darkness, we have used image intensification and infrared videography and three-dimensional analysis in the lab to demonstrate that each luminescent display train, which can be up to 60 cm long, consists of two distinct luminescent and swimming phases. The first, or 'stationary,' phase consists of three (usually) bright, longer pulses placed close together, with the male swimming in a looping pattern. We hypothesize that this pattern acts as an attention-grabbing signal for receptive females. The stationary phase is followed by the 'helical phase,' which consists of about a dozen evenly placed dimmer, shorter pulses secreted by an individual male rapidly spiraling upward in a helical pattern. We hypothesize that this phase, which has very uniform interpulse intervals and distances, helps an approaching female target and intercept the rapidly moving male. Here we provide details of these two phases, and produce a three-dimensional model of a multiply-displaying male.

Multilayer transparent electrode consisting of silver alloy layer and metal oxide layers for organic luminescent electronic display device

A transparent electrode for an organic luminescent electronic display (OLED) requires higher transmittance and higher electric conductivity to reduce the power consumption, in order that more of the current injected into the display results in luminescence. The authors made transparent conductive multilayer coatings including layers of silver alloy with 1wt% of palladium (Pd) and 1wt% of copper (Cu) (APC) and transparent metal oxide thin film layers for the transparent electrode of an OLED. Indium tin oxide (ITO) and zinc aluminum oxide (AZO) were used as the transparent metal oxides. A multilayer transparent electrode consisting of ITO/APC/ITO and one of AZO/APC/AZO prepared by dc magnetron sputtering achieved transmittance of more than 80% in the wavelength of 450–700nm with sheet resistance of less than 10Ω∕◻. An OLED device employing a multilayer transparent electrode consisting of ITO/APC/ITO emitted light with a higher efficacy than that employing a single layer ITO. On the other hand, the multilayer transparent electrode consisting of AZO/APC/AZO did not emit light even though higher corrosion resistance than ITO/APC/ITO was expected.

Efficient green and red upconversion emissions inEr3+/Yb3+ co-doped ZnAl2O4 phosphor obtained by combustion reaction

Thin ceramic powders of zinc aluminateZnAl2O4 co-dopedwith Er3+ and Yb3+ were prepared by a combustion reaction and characterized from the spectroscopic point ofview, with the aim of investigating the effect and mechanisms of upconversion emissions.The characteristic cubic spinel structure was predominantly formed for all doped samples,and intense upconversion emission was observed in the green and red spectralregions, under 980 nm diode laser excitation. The upconversion mechanism of bothemissions was confirmed to involve two photon absorptions and it was foundthat the efficiencies of the emissions are considerably enhanced by increasing theYb3+ concentration inrelation to Er3+. The resultsindicate the potential of ZnAl2O4:Er3+,Yb3+ phosphor powders for applications in luminescent display panels and other photonicdevices.

Analysis of visual pigment absorbance and luminescence emission spectra in marine ostracodes (Crustacea: Ostracoda)

1. 1. The luminescence emission spectra and the visual pigment absorbance spectra in digitonin extracts were examined and compared for marine luminescent ostracodes. 2. 2. The rhodopsin absorbance spectrum of one non-luminescent species was determined for comparison. 3. 3. For all species examined ( Vargula tsujii, V. graminicola and Skogsbergia lerneri), the difference spectra for visual pigment absorbance peaked at 460 nm. 4. 4. The luminescence emission spectra were measured by means of a computer controlled optical multi-channel analyser (OMA). 5. 5. For the two luminescent species examined ( V. graminicola and V. shulmanae), the λ max of the emitted light was 473 nm with full width at half maxima (FWHM) of about 80 nm. 6. 6. The luminescence emission spectra were also determined for male/female, adult/juvenile and dried/live pairs of V. graminicola. 7. 7. All had a λ max of 473 nm and in all cases the curves were unimodal with the FWHM of 80 nm. 8. 8. V. graminicola and V. shulmanae are found in Panama in the Caribbean and the males emit their luminescence in complex display patterns (signals) for purposes of attracting receptive females. 9. 9. Since the emission spectra for these two signalling species were similar, it would appear that species recognition is not based on wavelength but rather some other aspect of the luminescent display.

A data acquisition and analysis system for voltage versus luminous intensity transfer characteristic measurements in flat panel displays

In this study the time domain transfer function h(t) of luminescent display panels has been determined for the first time by the cross-correlation technique. The signature of the impulse response is immediately useful as a research tool and has potential application in the control of manufacturing process parameters. A prototype data acquisition and analysis system was designed and constructed. The system was interfaced to a Thorn EMI 9813 photomultiplier. The primary application of the system, in this case, was to measure the forward transfer characteristics of ZnS:Mn,Cu DCEL (DC electroluminescence) pixels. The system employs cross-correlation techniques based on a 1023, PRBS (pseudo random binary sequence) maximal length sequence with a bit rate of 50 kHz. The digitized luminous output is temporarily stored in static RAM. The data is subsequently transferred to a microcomputer where h(t) is derived by a cross-correlation algorithm.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Basic study on the gas-discharge panel for luminescent color display

With the objective of realizing a luminescent gas-discharge panel for color picture display, we made a comprehensive study of the various gas-discharge cells, including a planar positive-column (PPC) cell of our own design, with emphasis on the geometry of the gas discharge. First, ultraviolet spectroscopic measurements were performed on the PPC cell and on a conventional longitudinal cell filled with rare-gas mixtures. Next, the luminance characteristics of both types of phosphor-coated cells having various dimensions were examined from many points of view. As a result, fundamental differences in the luminescence characteristics between the positive column and the negative glow were revealed, demonstrating the excellence of the PPC cell for a luminescent color display. Furthermore, detailed measurements of luminance, luminous efficiency, and chromaticity were made for PPC cells coated with phosphors for the three primaries, giving basic data for the design of an actual display panel.