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Featuring a combination of size-tunable emission wavelengths, high thermal stability, and low cytotoxicity, carbon quantum dots (CQDs) have opened up a new possibility for next-generation displays. However, the theoretically highest external quantum efficiency (EQE) limit of electroluminescent light-emitting diodes (LEDs) based on fluorescent CQDs is 5% due to the spin-forbidden nature of triplet state transitions. Comparatively, phosphorescent or delayed fluorescence CQDs are expected to overcome this limitation and allow the EQE of the devices to reach nearly 25%. At present, the preparation of CQDs with good solution processability, narrow bandwidth emission, and full-color phosphorescence or delayed fluorescence still faces great challenges. Herein, this review aims to offer a materials-chemistry perspective to tailor highly efficient phosphorescent or delayed fluorescence CQDs and present their applications in electroluminescent LEDs for the display technology. The mechanism and design principle of pure organic phosphorescence and delayed fluorescence as well as their recent advances in electroluminescent devices are summarized. Furthermore, we focus on the prospects and challenges for phosphorescent and delayed fluorescence CQDs in displays. We hope that this review will further stimulate the development of high-performance CQD-based electroluminescent displays with a combined effort from different disciplines.

The visualization of accurate colour information using quantum dots has been explored for decades, and commercial products employing environmentally friendly materials are currently available as backlights1. However, next-generation electroluminescent displays based on quantum dots require the development of an efficient and stable cadmium-free blue-light-emitting device, which has remained a challenge because of the inferior photophysical properties of blue-light-emitting materials2,3. Here we present the synthesis of ZnSe-based blue-light-emitting quantum dots with a quantum yield of unity. We found that hydrofluoric acid and zinc chloride additives are effective at enhancing luminescence efficiency by eliminating stacking faults in the ZnSe crystalline structure. In addition, chloride passivation through liquid or solid ligand exchange leads to slow radiative recombination, high thermal stability and efficient charge-transport properties. We constructed double quantum dot emitting layers with gradient chloride content in a light-emitting diode to facilitate hole transport, and the resulting device showed an efficiency at the theoretical limit, high brightness and long operational lifetime. We anticipate that our efficient and stable blue quantum dot light-emitting devices can facilitate the development of electroluminescent full-colour displays using quantum dots. Cadmium-free blue quantum dot light-emitting diodes are constructed with a quantum yield of unity, an efficiency at the theoretical limit, high brightness and long operational lifetime.

A stretchable alternating current electroluminescent display seamlessly combines the light-emitting capabilities with mechanical compliance, which offers exciting opportunities for applications in wearable gadgets, soft robots, and fashion designs. The widespread adaption to deformable forms of optoelectronics is currently impeded by the tedious and labor-intensive fabrication process. This study reports an efficient and scalable procedure to create a fully screen-printed, multicolor, and stretchable electroluminescent display. The as-prepared device exhibits excellent deformability and low-voltage operation. The practical implementation is demonstrated by creating a wearable sound-synchronized sensing system with an epidermal display responsive to the rhythm of music. The ink formulation and printing procedure developed here pave the way for convenient fabrication of stretchable electronic devices.

The patterning of silver nanowires (AgNWs) is subject to critical challenges, which have seriously limited their practical applications. This work describes a simple and efficient method combining screen printing with vacuum filtration for patterning AgNW networks. The screen-printed poly(dimethylsiloxane) (PDMS) mask layer was shown to be strongly adhered to the filtration membrane, which resulted in well-defined sharp edges of the deposited AgNW patterns, and a 50 μm patterning resolution was achieved. The patterned films with low densities of AgNWs (≤15 μg/cm2) were transferred to the surface of PDMS to make patterned stretchable transparent conductive films (TCFs). The low sheet resistance of 7.3 Ω/sq was achieved at an optical transmittance of 79.6% (at 550 nm wavelength) with a AgNW deposition density of only 12.5 μg/cm2. As an application example, the patterned TCFs were used as the top electrodes to fabricate stretchable alternating current electroluminescent (ACEL) displays with stretchability up to 70% of their original dimension, which were applied to a smart system for simulating heart beats together with a digitally operated flexible circuit. The ACEL device exhibited a bright and uniform emission with a clear and smooth edge even with a pattern width as narrow as 100 μm, as well as exceptional elasticity and durability in spite of bending, stretching, and twisting. The present work provides a new way of patterning AgNWs and can be extended to a variety of applications.

Development of a human-interactive display enabling the simultaneous sensing, visualisation, and memorisation of a magnetic field remains a challenge. Here we report a skin-patchable magneto-interactive electroluminescent display, which is capable of sensing, visualising, and storing magnetic field information, thereby enabling 3D motion tracking. A magnetic field-dependent conductive gate is employed in an alternating current electroluminescent display, which is used to produce non-volatile and rewritable magnetic field-dependent display. By constructing mechanically flexible arrays of magneto-interactive displays, a spin-patchable and pixelated platform is realised. The magnetic field varying along the z-axis enables the 3D motion tracking (monitoring and memorisation) on 2D pixelated display. This 3D motion tracking display is successfully used as a non-destructive surgery-path guiding, wherein a pathway for a surgical robotic arm with a magnetic probe is visualised and recorded on a display patched on the abdominal skin of a rat, thereby helping the robotic arm to find an optimal pathway., Designing human-interactive displays enabling the simultaneous sensing, visualization, and memorization of a magnetic field remains a challenge. Here, the authors present a skin-patchable magneto-interactive electroluminescent display by employing a magnetic field-dependent conductive gate, thereby enabling 3D motion tracking.

In the preceding decade, the metal complexes of lanthanide ions with light harvesting organic chromophores have garnered intensive and greater attention due to their marvelous performance in various advanced fields. Researches in the field of organic compounds that sensitize the luminescence phenomenon in lanthanides enforce the advancement in the preparation of novel lanthanide compounds. Better emission properties, fine color gamut and high luminescent efficiency of lanthanide complexes makes them a suitable material for electroluminescent display devices and solid state lighting. Such complexes are extensively used to manufacture optoelectronic gadgets which show occasions to conquer energy-pertinent issues. In this review, molecular structure and spectroscopic characteristic data of lanthanide complexes as an emanating layer in organic light-emitting diodes (OLEDs) have been represented systematically. The design principles, methods of device fabrication and various characterization techniques for OLEDs are described. Electroluminescent devices based on the lanthanide complexes have gathered much awareness and possess various applications in efficient energy displays, solid-state lighting and the automotive sector. The immense review on OLEDs presumes that our current lighting network can be supplanted with OLEDs, an energy saving lighting innovation.

Stretchable polymer composites are a new group of materials with a wide range of application possibilities in wearable electronics. The purpose of this study was to fabricate stretchable electroluminescent (EL) structures using developed polymer compositions, based on multiple different nanomaterials: luminophore nanopowders, dielectric, carbon nanotubes, and conductive platelets. The multi-layered EL structures have been printed directly on textiles using screen printing technology. During research, the appropriate rheological properties of the developed composite pastes, and their suitability for printed electronics, have been confirmed. The structure that has been created from the developed materials has been tested in terms of its mechanical strength and resistance to washing or ironing.

Alternating Current Electroluminescence (ACEL)was measured in orange and blue phosphors and a mixture of them in a ratio of 2: 1. The phosphor, dielectric and top silver electrodes were prepared by screen printing. Nowadays ACEL is presented on the market as the only technique for quick and easy preparation of large area, low cost electroluminescent panels by the means of material printing. From the optical microscope images, we could conclude that the radiation of blue phosphor dominates over the orange one. These results are confirmed in the absolute irradiance spectra. Moreover, using samples, based on phosphor stripes leads to a decrease of the total irradiance, but, on the other hand, the uniformity of the emitted EL light is improved. Printing of striped active layer is preferred from the point of view of achieving more uniformly distributed light. The summarized fitting parameters show that driving frequency around 300 Hz will produce white light with reasonable intensity and with values of x, y coordinates higher than 0.31. The somewhat lower intensity of the emitted light can be improved by setting higher driving AC voltage. The voltage tested in this work was set to be constant at 250 V pp .

Stretchable alternating-current electroluminescent (ACEL) devices are required due to their potential in wearable, biomedical, e-skin, robotic, lighting, and display applications; however, one of the main hurdles is to achieve uniform electroluminescence with an optimal combination of transparency, conductivity, and stretchability in electrodes. We therefore propose a fabrication scheme involving strategically combining two-dimensional graphene layers with a silver nanowire (Ag NW)-embedded PEDOT:PSS film. The developed hybrid electrode overcomes the limitations of commonly known metallic NWs and ionic conductor-based electrodes for ACEL applications. Furthermore, the potential of the hybrid electrode is realized in demonstrating large-area stretchable ACEL devices composed of an 8 × 8 passive array. The prototype ACEL passive array demonstrates efficient and uniform electroluminescence under high levels of mechanical deformation such as bending, rolling, twisting, and stretching.

Electroluminescence (EL) of commercial phosphor pastes was investigated and an equivalent circuit of the EL stack was determined. The model was used to develop a simple driver electronics capable to operate electroluminescent displays (ELD) with a good contrast and visibility. Flexible displays with a passive matrix of 32 × 5 pixels and up to 11 pictogram elements were produced by screen printing on PET foil and combined with the driver to form a standalone unit. Several demonstrators with the ELDs integrated into a bag or a back pack were manufactured with the primary goal to allow traffic signalling for cyclists or skaters during the dark periods of day; the displays were controlled wirelessly using either a smartphone or a dedicated control device. Present work describes technical implementation details of the printed electroluminescent display and its driving electronics. The following aspects are discussed: empirical model of the EL stack, intensity of emitted light in dependence of driving voltage and frequency, waveforms used for driving the ELD, implemented driver circuit, layout and packaging considerations for the display module.

Lanthanide complexes are widely used as emitters for applications in the fields of bioimaging, molecular sensing, disease diagnosis, and optoelectronics. Particularly, the high luminescence efficiencies of these complexes make them attractive for electroluminescent display and solid-state lighting. As color purity and saturation are the most stringent criteria for red emission in display technology, europium(III) complexes featuring an emission peak centered at ∼612 nm with a narrow bandwidth hold great potential as red-emitting materials. This review highlights the recent development of electroluminescent europium(III) complexes, with emphasis on correlations between molecular structures and optoelectronic performance. After a fundamental introduction on the optical and electrical properties of europium(III) complexes, efforts will be devoted toward the controlled synthesis and functionalization of molecules for improved charge injection/transportation, good processability, and enhanced emission efficiency.

A screen-printed electroluminescent display with different sensing capabilities is presented. The sensing principle is based on the direct relationship between the light intensity of the lamp and the conductivity of the external layers. The proposed device is able to detect the ionic concentration of any conductive species. Using both top and bottom emission architectures, for the first time, a humidity sensor based on electroluminescent display functionalized by a graphene oxide nanocomposite is introduced. In this regard, just by coupling the display to a smartphone camera sensor, its potential was expanded for automatically monitoring human respiration in real time. Besides, the research includes a responsive display in which the light is spatially turned on in response to pencil drawing or any other conductive media. The above mentioned features together with the easiness of manufacturing and cost-effectiveness of this electroluminescent display can open up great opportunities to exploit it in sensing applications and point-of-care diagnosis., We acknowledge financial support from EU Graphene Flagship Core 2 Project (No. 785219). This work is also funded by the CERCA Program/Generalitat de Catalunya. ICN2 is supported by the Severo Ochoa program from the Spanish MINECO (Grant No. SEV-2013-0295). A.Y. and O.C. thank the Science Achievement Scholarship of Thailand (SAST), the Thailand Research Fund via the Research Team Promotion Grant (RTA6080002) and the Ratchadaphisaksomphot Endowment Fund of Chulalongkorn University. A.M. thanks Silver Merkoci̧ from Gwent Electronic Materials Ltd./Sun Chemical for his inspiring discussions on the use of electroluminescent materials in sensing. R.Á.-D. acknowledges the financial support from the CONACYT (Mexico).

A novel geometry for electroluminescent devices, which does not require transparent electrodes for electrical input, is demonstrated, theoretically analyzed, and experimentally characterized. Instead of emitting light through a conventional electrode, light emission occurs through a polar liquid or solid and input electrical electrodes are coplanar, rather than stacked in a sandwich configuration. This new device concept is scalable and easily deployed for a range of modular alternating-current-powered electroluminescent light sources and light-emitting sensing devices. The polar-electrode-bridged electroluminescent displays can be used as remotely readable, spatially responsive sensors that emit light in response to the accumulation and distribution of materials on the device surface. Using this device structure, various types of alternating current devices are demonstrated. These include an umbrella that automatically lights up when it rains, a display that emits light from regions touched by human fingers (or painted upon using a mixture of oil and water), and a sensor that lights up differently in different areas to indicate the presence of water and its freezing. This study extends the dual-stack, coplanar-electrode device geometry to provide displays that emit light from a figure drawn on an electroluminescent panel using a graphite pencil.

We investigated blue fluorescent organic light-emitting diode (OLED) with a charge control layer (CCL) to produce high efficiency and improve the half-decay lifetime. Three types of devices (device A, B, and C) were fabricated following the number of CCLs within the emitting layer (EML), maintaining the thickness of whole EML. The CCL and host material, 2-methyl-9,10-di(2-naphthyl)anthracene, which has a bipolar property, was able to control the carrier movement with ease inside the EML. Device B demonstrated a maximum luminous efficiency (LE) and external quantum efficiency (EQE) of 9.19 cd/A and 5.78%, respectively. It also showed that the enhancement of the half-decay lifetime, measured at an initial luminance of 1,000 cd/m2, was 1.5 times longer than that of the conventional structure. A hybrid white OLED (WOLED) was also fabricated using a phosphorescent red emitter, bis(2-phenylquinoline)-acetylacetonate iridium III doped in 4,4'-N,N'-dicarbazolyl-biphenyl. The property of the hybrid WOLED with CCL showed a maximum LE and an EQE of 13.46 cd/A and 8.32%, respectively. It also showed white emission with Commission International de L'Éclairage coordinates of (x = 0.41, y = 0.33) at 10 V.

Optoelectronic materials can source, detect, and control light wavelengths ranging from gamma and x rays to ultraviolet, visible, and infrared regions. Optoelectronic devices are usually systems that transduce electricity to optical signal or vice versa. Optoelectronic devices include many modern necessities such as lamps, displays, lasers, solar cells, and various photodetectors. Some important research topics in the field of optoelectronics materials are development of new materials, new technologies for fabricating materials, and design of device structures. Atomic layer deposition (ALD) is a technology that was developed in the early 1970s for manufacturing high-quality luminescent and dielectric films to be used in AC-driven thin film electroluminescent (TFEL) displays. Monochromic yellow-black displays based on a ZnS:Mn luminescent layer have been manufactured industrially using ALD since the mid-1980s. Multicolor displays (green-yellow-red) were successfully realized by filtering the broad emission band of ZnS:Mn or adding another luminescent material, e.g., green-emitting ZnS:Tb or SrS:Ce. However, applicable full-color AC TFEL devices could not be developed because of the lack of an efficient deep blue-emitting phosphor. Currently, the most promising application area in TFEL displays is transparent displays, which are commonly used in various vehicles. In the mid-1980s, epitaxial III-V semiconductors were studied using ALD. It was shown that manufacturing real epitaxial [atomic layer epitaxy (ALE)] films is possible for different III (Al, Ga, In) and V (N, P, As) materials. The advantages of ALE processing compared to more traditional metalorganic chemical vapor deposition or molecular beam epitaxy methods have remained low, however, and ALE is not used on a large scale. Research continues to be carried out using ALE, especially with nitride films. Thin film solar cells have continuously received attention in ALD research. ALD films may be used as both an absorber (CdTe, SnS) and a passivation [In2S3, Zn(O,S)] material. However, in the solar cell field, the real industrial-level use is in passivation of silicon cells. Thin ALD Al2O3 film effectively passivates all types of silicon cells and improves their efficiency. Transition metal dichalcogenides are emerging 2D materials that have potential uses as channel materials in field-effect transistors, as well as phototransistors and other optoelectronic devices. The problem with achieving large-scale use of these 2D materials is the lack of a scalable, low-temperature process for fabricating high-quality, large-area films. ALD is proposed as a solution for these limitations. This review covers all of these ALD applications in detail.Optoelectronic materials can source, detect, and control light wavelengths ranging from gamma and x rays to ultraviolet, visible, and infrared regions. Optoelectronic devices are usually systems that transduce electricity to optical signal or vice versa. Optoelectronic devices include many modern necessities such as lamps, displays, lasers, solar cells, and various photodetectors. Some important research topics in the field of optoelectronics materials are development of new materials, new technologies for fabricating materials, and design of device structures. Atomic layer deposition (ALD) is a technology that was developed in the early 1970s for manufacturing high-quality luminescent and dielectric films to be used in AC-driven thin film electroluminescent (TFEL) displays. Monochromic yellow-black displays based on a ZnS:Mn luminescent layer have been manufactured industrially using ALD since the mid-1980s. Multicolor displays (green-yellow-red) were successfully realized by filtering the broad emission...

Electroluminescent (EL) lamps are flat solid-state ac driven devices in which light is generated by impact excitation to optical energies of luminescent centers in a Mn-, Cu-, or Tb-doped ZnS phosphor layer by high-energy electrons and radiant decay to the ground state of these luminescent centers. They are useful in applications which require diffuse low-level uniform illumination. This paper presents measurements of light emission and related spectra of EL lamps as a function of operation frequency and sinusoidal voltage amplitude. The excitation of other voltage waveforms is also analyzed, and parameters of the equivalent electrical circuit are presented.

The combination of a SiO2 electron accelerator layer with a silicon-rich nitride layer forming a bilayer embedded in a metal-oxide-semiconductor structure has proved to enhance the integrated visible-infrared EL intensity by more than two orders of magnitude in comparison to the single-layer electroluminescent device approach. The origin of such an improvement is attributed to the massive ionization of defects in the silicon-rich nitride layer by direct impact of injected hot electrons coming from the SiO2 conduction band. Our premises are further corroborated by performing a thorough study of the charge transport in the bilayer structure. This study displays a main electrical mechanism at steady state that combines hot-electron tunneling injection from the SiO2 accelerator layer and space charge-limited current enhanced by Poole-Frenkel conduction from the silicon-rich nitride electroluminescent layer. The proposed electrical mechanism is validated by numerical simulations that provide good agreement with the experimental behavior. These results point out the feasibility of boosting electroluminescence efficiency of Si-based light emitting devices by performing an adequate gate stack engineering that maximizes the hot-electron injection into the electroluminescent layer.

Advances in image quality in recent decades have made it necessary to develop new technologies for producing displays to meet remarkably stricter standards. The display market is governed mainly by liquid crystal display and light-emitting diode (LED) technology; however, it suffers from limitations that can be overcome by developing the next generation of electroluminescent displays. The introduction of colloidal quantum dots (QDs) as down-converters has enabled the production of displays with extremely high color purity and gamut. Therefore, colloidal nanocrystals are excellent candidates for the preparation of electroluminescent devices, which represent a straightforward approach to the development of unprecedented high-quality displays. We synthesized light-emitting QDs covering the entire visible spectrum with high fluorescence quantum yields and color purity, and produced high-brightness single-color LEDs with external quantum efficiencies of 0.39%, 1.04%, 2.10%, and 1.30% for red-, orange-, green-, and blue-emitting dots, respectively. Additionally, white LEDs were prepared by mixing QDs; they showed color temperatures of 5,300 K and color rendering indices exceeding 80%. Very importantly, we exhaustively characterized the LED performance, including the response time, stability, and evolution of the light characteristics, thus providing crucial information toward the development of high-quality electroluminescent displays.

In this demo we aim to demonstrate final design and hardware implementation of our large and fully flexible electroluminescent based 48 X 48 pixel display (ELD) panel. Each panel is 45 X 45 cm and they can be connected horizontally to increase overall area. EL is an enabling technology for highly flexible, robust and large-scale displays production. The display has a very simple layer structure and it can be printed manually without need for a specialized manufacturing facility. Due to the high voltage alternating field nature of an EL main complexity comes down to the driving circuitry. We also implemented a stackable, high voltage display driver circuit architecture to further ease the control and expansion of our display.

An extremely stretchable electroluminescent device is fabricated by P. S. Lee and co-workers, as described on page 4490. The stretchable alternating-current electroluminescent (ACEL) device possesses extremely high stretchability, and can be linearly stretched to 700% with the luminance being maintained at 70% of the initial value before stretching. The device can be repeatedly stretched to 400% with stable emission behavior. The presented device will provide new opportunities in stretchable lighting, volumetric 3D displays, interactive readout systems, and other unprecedented applications.

A high permittivity composite is developed to enhance the brightness of stretchable electroluminescent displays. The unique two-step assembly process yields dense layers, in which the voids around the electroluminescent particles are filled with smaller high dielectric particles. A stretchable seven-segment display based on the composite is bright enough to be used under standard indoor lighting conditions.

[EN] Many types of solutions have been studied and developed in order to give the user feedback when using touchpads, buttons, or keyboards in textile industry. Their application on textiles could allow a wide range of applications in the field of medicine, sports or the automotive industry. In this work, we introduce a novel solution that combines a 2D touchpad with an electroluminescent display (ELD). This approach physically has two circuits over a flexible textile substrate using the screen-printing technique for wearable electronics applications. Screen-printing technology is widely used in the textile industry and does not require heavy investments. For the proposed solution, different layer structures are presented, considering several fabric materials and inks, to obtain the best results., This work was supported by Spanish Government/FEDER funds (grant number MAT2015-64139-C4-3-R (Mineco/Feder)). The work presented is also funded by the Conselleria d'Economia Sostenible, Sectors Productius i Treball, through IVACE (Instituto Valenciano de Competitividad Empresarial) and cofounded by ERDF funding from the EU. Application No.: IMAMCI/2017/1.

Alternating-current-type inorganic powder electroluminescence (PEL) devices were successfully fabricated on four kinds of paper substrates, i.e., glossy paper, sticker paper, magazine paper, and newspaper. To protect the paper from wet chemical and heating processes during the formation of the PEL device, the paper substrate was coated with a spin-on-glass layer that served as a buffer layer. In spite of the fragility of paper, quite satisfactory results were obtained-the performance of paper-based PEL devices was almost equivalent to that of PEL devices on a plastic substrate. Extension of a substrate to paper, even to flimsy daily newspaper, will widen the opportunity of PEL devices as one of flexible and disposable displays.

Our challenge is to fabricate practical all-inorganic electroluminescent devices using colloidal quantum dots with presenting new aspects of electroluminescence mechanisms. The electric field effect on the excitation of a quantum dot with a hot electron that results in saturated chromatic electroluminescence was studied by time-resolved spectral transient properties at room temperature. Fast and very slow radiative recombination transition pathways are newly distinguished in the electroluminescence related to carrier confinement in the quantum dot under an electric field.

Luminescent organic and metal coordination compounds have attracted considerable attention for their potential applications in electroluminescent displays. Among coordination compounds, chelate d metal complexes are of great interest due to their high thermal stability and low cost as well as their good photoluminescent and electroluminescent properties. For example, Zn(II) complexes with nitrogen and oxygen donor atoms exhibit blue and white emissions. Meanwhile, less luminescent Hg(II) complexes have been reported. Recently some coordination polymeric Hg(II) complexes have shown blue fluorescence originating from intraligand charge transfer (ILCT) transitions. Herein, two novel d metal (M = Znand Hg) complexes with 2-[4-(dimethylamino)styryl] pyridine (dmasp) were prepared and their structural and luminescent properties were investigated. The dmasp ligand was of interest as it had an electron push-pull system, thereby stabilizing the π* levels and, in them, ILCT transitions could arise readily through a conjugated π system, which is also important to ILCT photoluminescent materials as well as the second-order nonlinear optical (NLO) materials.

The novel complexes Eu(HMAP) 3 ·2H 2 O and Tb(HMAP) 3 ·2H 2 O (where HMAP = 2′-hydroxy-4′-methoxyacetophenone) are synthesized and characterized by infra red spectroscopy, 1 H NMR spectroscopy, TGA/DTA, SEM and elemental analysis. The qualitative analysis of the complexes to detect the presence of rare earth (Eu, Tb), have been performed by energy dispersive analysis (EDX). The Eu(HMAP) 3 ·2H 2 O on excitation at 354 nm emits bright red luminescence with main peak at 612 nm and Tb(HMAP) 3 ·2H 2 O on excitation at 354 nm emits bright green luminescence with main peak at 547 nm. The luminescence intensity of Eu(HMAP) 3 ·2H 2 O is higher than Tb(HMAP) 3 ·2H 2 O. These complexes emitting red and green luminescence might be used to make the electroluminescent (EL) devices for display applications.

In this study, an active matrix pixel was fabricated and characterized using indium gallium zinc oxide (IGZO) thin-film transistors and a novel electroluminescent (EL) Eu:IGZO thin-film phosphor. The results show that even large and unoptimized IGZO devices are capable of modulating at the frequencies necessary for modern display technology. Furthermore, we demonstrate a rare-earth doped amorphous-oxide semiconductor (AOS) EL phosphor that can be modulated via a TFT.

Statistical designs of experiments were applied in order to understand the effect of processing variables on the brightness of inorganic electroluminescent displays. The main effects and interaction of phosphor and dielectric layers are estimated to be statistically significant. Additional improvement was made on removing the pores in the thick films, using the defoaming in pastes and cold isostatic pressing in bonding the top and bottom parts of the inorganic electroluminescent devices. Such optimization contributed to the reduction in the corresponding threshold voltage and enhancement in the brightness.

The inorganic high‐luminosity electroluminescent (EL) panel used in this study is a distributed‐type EL panel, which can be produced using a printing technique. We obtained a panel with a high luminosity of 7940 cd/m2 at 6 kHz. In addition, we believed that the panel temperature and luminosity of this panel were closely related. Therefore, we considered the relationship between the temperature change in the dielectric layer and the luminosity since this relationship is responsible for the supply of electric charge to the phosphor layer. A change in the amount of electric charge by heating in a high‐voltage domain originates at the Curie point of BaTiO3 ferroelectric particles. This indicates that the influence of BaTiO3 was strong.

Eu-activated BaAl2S4 (BaAl2S4:Eu) blue light emission phosphor has attracted considerable attention recently as a prospective material for full color electroluminescent display applications. Although BaAl2S4:Eu was discovered over 30 years ago, the solid-state reaction between metal sulfides in sealed quartz ampoules remains the main method for the synthesis of this material. In this work, a homogeneous single-phase Ba0.95Eu0.05Al2S4 (BaAl2S4:Eu) phosphor was obtained by the sulfurization–reduction of the multicomponent oxide precursor in a CS2 atmosphere at 1050°C. The oxide precursor containing barium, aluminum, and europium for this process was prepared by the polymerizable complex method, which ensures a high degree of homogeneity in the final product. The BaAl2S4:Eu material thus obtained exhibited a single emission line at 475 nm and a fluorescence intensity of 35% compared with one of the best commercially available (Ba,Eu)MgAl10O17 phosphors.

The optical and photoluminescent properties of plasma polymer layers synthesized from hexamethyldisiloxane are examined. The value of the polymer layer transparence is in the limits from 55% at 400 nm to 88% at 800 nm. Photoluminescence is stimulated by using the spectral line λ =365 nm emitted by a Hg spectral lamp. The organosilicon plasma polymers are included as protective and capsulating layers in electroluminescent (EL) structures. The structure obtained is characterized by a significant increase in emission brightness, compared to inorganic protective layers. For EL structures with a chalcogenide protective layer the increase is more than 6 times and for structures with heterogeneous matrix on the base of TiO 2 it is more than 20 times. As a stable covering the organosilicon plasma polymer increases the lifetime of the EL structures too.

The intensity of electroluminescence from an electroluminescent phosphor (electrophosphor) excited by unipolar voltage pulses with a linear front is studied. Based on experimental data, an expression for the free carrier emission rate in a planar electroluminescent capacitor with the polarization mechanism of luminescence is derived.

We report a low temperature fabrication and light-emitting characteristics of inorganic electroluminescent (EL) devices in which a CdSe/ZnS quantum dot (QD) layer was formed by a new ion beam deposition process. The deposition process was developed for fabrication of surfactant- and solvent-free QD structured films from colloidally dispersed QD solution. The electroluminescence spectra of the alternating field driven devices were found to be identical to the photoluminescence spectra of the source solution. The finding paves the way for the development of full color, transparent, flexible, and low-cost large area flat panel displays.

An alternating current electroluminescent display has been direct written onto a flexible plastic substrate. A hybrid layer of poly(2-methoxy,5(2-ethylhexyloxy)-p-phenylene vinylene) (MEH-PPV) and CdSe quantum dots (QDs) were used to convert the light emitted by electroluminescent ZnS phosphor into red light. The emission wavelength of the display is found to be directly related to the emission of CdSe quantum dots. The integration of QDs into thin film electroluminescent (TFEL) displays has the potential to enhance its color spectrum.

Light-emitting display is one of the information display techniques that utilize conversion of electrical energy into light energy. In this study, new luminescent material, 1,4-dihdoxy-5,8-naphtquinone·Alq 3 complex (Alq 2 –Nq) was synthesized. And extended efforts had been made to obtain high-performance electroluminescenct (EL) devices, since the first report of organic light-emitting diodes (OLEDs) based on Tris(8-hydroxyquinoline) aluminium (Alq 3 ). We used hole injection layer of powdered TPD to improve hole injection and characteristics of interface in OLEDs. Current–voltage characteristics, luminance–voltage characteristics and luminous efficiency were measured by Flat Panel Display Analysis System (Model 200-AT) at room temperature. PL spectra is measured by LS45 (Perkin-Elmer instruments) at room temperature.

Department of Molecular Science and Technology, Ajou University, Suwon 442-749, Korea(Received October 12, ) 2004 : , , , Kords:ewy Fluor ectesce EalslulromM,iecener nstan Dtieevi,cEce,fficien cy (Electroluminescence, EL) ! $ "#% &'( )" *+ -. ) , /% 0 1 4& 23 1963 5 Pope

An improved thick dielectric (TD) layer for inorganic electroluminescent (EL) display devices has been achieved through a composite high-/spl kappa/ dielectric sol-gel/powder route. This composite TD film results in a luminance improvement (up to 10/spl times/) in these TDEL devices with Eu-doped GaN and Mn-doped ZnS phosphor layers. The use of a composite TD film, composed primarily of lead-zirconate-titanate (PZT), results in a significantly higher charge (>3 /spl mu/C/cm/sup 2/) coupling to the phosphor layer. Furthermore, the reduction in porosity of the TD has improved the homogeneity of electric field applied to the phosphor layer, resulting in a steeper luminance-voltage slope. The reduction in porosity has also decreased the diffuse reflection of the TD, which when pigmented, exhibits a diffuse reflectivity of

White organic electroluminescent devices fabricated using the ink-jet printing method have been investigated. The solution of organic materials was composed of a hole transport material, an electron transport material and an emission material dissolved in 1,2-dichloroethane. A maximum luminance of 3,600 cd/m2, maximum external quantum efficiency of 4.15% and Commission International de l'Eclairage chromaticity of (x,y)=(0.29,0.33) have been obtained from the device with poly(9-vinylcarbazole) as host material, 2,5-bis(1-naphthyl)-1,3,4-oxadiazole as electron transport material, a mixture of perylene and 4-dicyanomethylene-6-cp-julolidinostyryl-2-tert-butyl-4H-pyran as emission materials, and cesium as cathode.

The self-aligned bank formation of organic electroluminescent devices using the ink-jet printing method was proposed and investigated. A solution of organic materials mixed with host and emission materials was printed on an indium–tin–oxide-coated glass substrate covered with an insulating polymer layer. The insulating material was dissolved in a solvent, and a mixture of organic materials was formed at the same position as that of the ink-jet-printed region, that is, a self-aligned organic electroluminescent device was realized. The diameter of the emission region was 200 µm and a luminance of 9,070 cd/m2 was obtained using an electrophosphorescent material.

A method of improving the luminance of zinc sulfide doped with manganese (ZnS/Mn) thin-film electroluminescent (TFEL) devices is suggested. The addition of small amounts of silver is found to increase the device luminance. It is suggested that silver reduces Mn clustering effects, thereby resulting in fewer nearest neighbor Mn re-absorption interactions and allowing higher Mn doping concentrations. A luminance increase of up to two and a half times from ZnS/Mn,Ag devices compared to ZnS/Mn is observed. The same magnitude of the luminance increase is demonstrated on ZnS/Ho,Ag samples. Silver was found to cause no change in the crystallite size of the phosphor layer and no additional degradation of the device.

Thin film electroluminescence (TFEL) displays are complex optoelectronic devices with challenging material requirement. The electrical characteristics of ZnS : Mn alternating current thin film electroluminescent devices grown by electron beam evaporation are assessed as function of voltage frequency and Mn concentration. The threshold voltage increases with increasing frequency of the applied voltage and saturation value of electroluminescence (EL) brightness increases linearly with the frequency of applied voltage. The EL brightness increases linearly with the frequency of the applied voltage. The EL brightness was found optimum for a particular activator concentration. A model is proposed and an expression is derived for the EL brightness, which is able to explain the dependence of the EL brightness on different parameters.

An inverted double insulating thin film electroluminescent display structure has been fabricated using all sol–gel methods. The active layer of ZnS:Mn has been produced by a sulfidation process following sol–gel deposition of ZnO:Mn. This layer is sandwiched between high-permittivity insulating tantalum pentoxide (Ta2O5) layers. A silicon substrate served as the lower electrode and a top transparent electrode of ZnO:Al can be used. This paper reports on the structural and electronic properties of the Ta2O5 insulators and the influence of their crystal structure on the luminescent properties of the device.

The electroluminescence properties of polymer light-emitting devices with and without an ultraviolet (UV)-shielding filter were studied. The polymer light-emitting devices were fabricated with poly(2-methoxy-5,2′-ethyl-hexyloxy-1,4-phenylene vinylene) as the light emitter and poly(ethylenedioxy thiophene) as the hole-transporting material. The UV-shielding filter was composed of alternating TiO2 and SiO2 dielectric multilayers made by a physical vacuum deposition process. The current density, brightness, and photometric efficiency decreased significantly for the polymer light-emitting device without the UV-shielding filter after irradiation by UV light. The decay of PLEDs due to UV degradation was greatly reduced by the UV-shielding filter. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1432–1436, 2004

This paper reviews the most significant steps in history of electroluminescent (EL) technology. It also discusses how the emerging organic light-emitting diode displays may benefit from the experience of thin-film electroluminescent devices.

In the later part of the twentieth century, classic cathode ray tubes (CRTs) are replaced by flat panel displays (FPDs) with a thinner, smaller size and with a significant reduction in power consumption. Such displays are currently used in several applications including mobile phones, laptops, and televisions. Among other FPDs, electroluminescent displays perform better than its counterparts such as liquid crystal, field emission, and plasma displays. Electroluminescent (EL) display is a common term for devices such as light-emitting diodes (LEDs), powder phosphor devices, thin film, and thick dielectric electroluminescent devices. Thin film EL devices (TFEL) show advantages such as quick response, high resolution, wide viewing angles and wide operating temperatures and so on. TFEL displays are all solid state and based on electroluminescence in which luminescent material gives light under high electric field.

The heat-transfer process described in this paper will be useful for controllably and selectively doping polymer films used to make hyperfine full-color polymer electroluminescent (EL) displays. A polymer receiver film is placed in direct contact with a dye-dispersed polymer film coated onto an efficient photo-absorbing substrate to permit heat-transfer dye diffusion. The widely used heat-mode magneto-optical storage material, TbFeCo was used as the photo-absorbing material. We irradiated it with a laser in order to generate heat. This method can be used to control the lateral and vertical dopant distributions in polymer films for EL devices. We demonstrated that coumarin 6 and Nile red can be doped into the rather thermally stable polymer poly( N -vinylcarbazole) containing the electron-transporting 2-(4-biphenylyl)-5-(4- tert -butyl-phenyl)-1,3,4-oxadiazole from a viewpoint of luminescent properties. The diffusion power and time for about 1-mm 2 doping area were 1.2 W and about 10 s.

A high contrast electroluminescent (EL) device structure is presented. The diffuse luminous reflectivity from the metal/dielectric/phosphor/indium-tin-oxide/glass EL device structure is /spl sim/3%. A Eu-doped GaN phosphor is used to demonstrate the contrast-enhanced operation. Low reflectivity is achieved by inserting a light-absorbing black thick-film BaTiO/sub 3/ layer between the phosphor and the rear metal electrode. In addition to providing contrast enhancement, the opaque thick dielectric film exhibits capacitance and high voltage reliability (40 nF/cm/sup 2/, dielectric constant /spl epsi//sub d/ /spl sim/ 500-1000, breakdown field E/sub d,br/ /spl sim/ 0.1-0.4 MV/cm) similar to that of the highest performance transparent thin-film dielectrics. An EL device luminance of only 20 cd/m/sup 2/ is sufficient for a display contrast ratio of /spl sim/10:1 under 140 lux indoor ambient lighting (illumination). Under sunlight illumination of 100000 lux, a display contrast ratio of >3:1 is expected with application of additional contrast enhancement techniques.