Search

The development of methods and means of testing the applicability of thin-film electroluminescent indicator devices as displays in aircraft is carried out. Thin-film electroluminescent displays are used in equipment and systems that require high image quality and reliability, as well as a long service life of the devices. The result of the performed work is the ExpAT program, which allows to carry out a computational experiment to test of the applicability of the TFEL indicator devices in aeronautical engineering. As a result of the computational experiment, variants of structures of thin-film emitting structures that meet the operating conditions of indicators in avionics are shown.

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.

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.

The light out-coupling properties of inorganic thin-film electroluminescent devices can be improved by using a new device structure with a light-scattering layer. This consists of particles dispersed in a binder and it can be laminated on the surface of conventional devices by screen-printing. The light-scattering layer increases the luminance to approximately three times that of conventional devices and reduces the viewing-angle dependence of the electroluminescent spectrum.

Spatial distributions of electron energy in two kinds of thin film electroluminescent displays were investigated through Monte Carlo simulation and experiments. In sandwich structure, the average energy of electrons in the region near the interfaces was found to be lower than that in the middle part of the phosphor layer. The result coincides with the dead layer phenomenon found in previous experiments. In layered optimization structure, due to the heating effect of accelerating layers, electrons near the interfaces are more energetic than those in the middle part of the phosphor layer. By using the ZnS:Er thin layer as a probe layer, such a spatial distribution was proved in our experiments.

We present new results on a single-layer organic alloy light emitting diode. The device shows significant improvement in lifetime at room and elevated temperatures. The improvement is attributed to the elimination of the heterointerface and the minimization of the formation of unstable tris-(8-hydroxyquinoline) aluminum (Alq3 ) cations. The efficiency is comparable to those of heterojunction counterparts. Balanced bipolar carrier injection and transport are made possible by adjusting the alloy composition and doping.

The performances such as the operating-voltage and the brightness of three types of devices: single-layer device, double-layer device and three-layer device, were examined. It is demonstrated that the I-V characteristics of single-layer device depends not on the applied voltage but instead on the electric-field strength, and the brightness increased by a factor of 50 and the operating-voltage decreased when introducing one electron transporting layer or an electron transporting layer and one hole blocking layer between the light emitting layer and the negative electrode. In fact, it is imperative to match the energy level of each layer in the electroluminescent device in order to improve its comprehensive performances.

Aiming at the problem of luminance uniformity for injection electroluminescent display panels, we present a new scan method for display panels according to successive scans theory. First, on the basis of the number of pixels requiring light emitting in one frame period, we adjust the scan time for each row. Secondly, for ensuring image transmission synchronization, the frame period must to be a constant. We adopt a 64 × 32 LED display panel as an example to expound the new scan method and we obtain the good result that the reduce amplitude of luminance non-uniformity is 31.34% and the increase amplitude of the average luminance value is 7.8258%.

In the present work plasma polymer films obtained from hexamethyldisiloxane have been implanted by carbon ions at three different doses. The photoluminescent properties of the implanted polymers were investigated. The optical transmission of these polymer layers was investigated in the visible spectral region. Their electrical parameters were also measured. It was found that the resulting changes do not worsen the protective properties of the implanted polymer layer. The variations in the properties studied might be ascribed to the nanostructured carbon clusters formed on the polymer surface. The results obtained could form the basis for further optimization of the polymer structure by carbon ion implantation in view of applications in electroluminescent display structures.

A color-variable electroluminescent diode has been realized utilizing a 1-nm-thick dye molecule layer with single-quantum-well (SQW) structure. The electroluminescent (EL) spectrum changes with increasing applied voltage from 8 V to 20 V. The result is discussed in terms of the shift of the recombination region toward the ITO electrode, depending on applied voltage.

A novel display device combining a polymer-dispersed liquid crystal (PDLC) film and a thin-film electroluminescent (TFEL) device was fabricated. This device may be used as a liquid crystal display (LCD) in strong light ambient. In the dark, it can be switched to become an electroluminescent display, providing high viewability. Measurements of its electrooptical characteristics showed that the breakdown voltage of the TFEL device did not change significantly with the addition of a LC layer. It implies that the cured polymer could provide an intrinsic barrier preventing LC material from diffusing into the TFEL device.

Electron cyclotron resonance hydrogen plasma reactive ion etching (RIE) with n-butyl acetate reactive gas has been demonstrated. The etching mechanism is discussed for RIE of transparent conducting oxide films. The RIE technique exhibits excellent material selectivity resulting from the ability to control the etching mechanism by altering the accelerating voltage frequency. To demonstrate the practical application of RIE, an electroluminescent display fabrication is described.

Presents an outline of the physics of LEDs and their construction and describes thick and thin film electroluminescnt devices. The author discusses the characteristics of each type of display and outlines some applications

Brightness and electrical characteristics of powder DCEL displays have been systematically measured during both the forming operation and simulated life testing. Of particular interest and novelty are the effects of different gaseous environments on display behaviour. Forming in inert or reducing gases is slow and a new phenomenon of 'sticking' is reported where the forming rate reduces to extremely low values (

For part I see ibid., vol.21, p.1627 (1988). A new way to describe the mechanism of forming of powder DC electroluminescent panels is proposed that is based on the hypothesis that the surface regions of the phosphor particles adjacent to the anode are oxidised. This irreversible chemical transformation produces the narrow resistive formed layer in which electroluminescence can occur. Electron conduction and photon production is controlled not only by the applied electric field but also by the internal fields within the particles derived from surface-adsorbed oxygen ions. The new observations reported in part I are explained and additional, confirmatory experiments are described. It is argued that identical physical and chemical processes control the brightness of pulsed DC-operated displays and some implications for the solution of the maintenance problem are discussed.

Experiments are reported on a converter in which radiation generated in an electroluminescent cell excites a photoluminescent material, so that by suitable choice of phosphor a long decay time may be achieved. Two kinds of converter have been considered, one with the electroluminescent and photoluminescent particles mixed, and one with them separated. The dependence of transfer characteristics and rise and decay times on the construction of the panels are discussed.

The d.c. and pulsed current give rise to an electroluminescent phenomenon in both of α- and β-SiC crystals. The α-crystals are composed of p–in–n junction along their c-axis and the light emission under forward bias takes place in the n-type region. The emission is conceived to originate from the emission centers in the n-type layer excited by the diffusion current flowing into the layer.

A study of the light output/current characteristics of epitaxial and diffused, red-emitting, GaP electroluminescent diodes shows that the output saturates at an emission density which is essentially constant for all diodes, irrespective of their efficiency.