The AC powder electroluminescent lamps (hereinafter refered to as EL) have the advantage of thin,flexibility and light weight. They are usually driven with the inverters to improve brightness and service life. We are studying various organic dielectric binders for EL. Thus,the brightness of EL are improved by applying cyanoethylated binder of monosaccharides. And we have developed long life and low frequency drivable EL which don't need inverters.

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ZnS: Cu, Cl electoluminescence phoshors have been prepared in the Re-Sintering Method It bightness value and lifetime inereased with increasing Hexa/Cub. ratio at 500〜1000℃ Frome several measurements, we Could alsoobtains the maimum EL efficiency cell that Hexa/Cub. is in the ratio of 3 to 1

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CdF_2, ZnF_2 and CaF_2 thin films have been performed by electron-beam evaporation, and the polycrystalline CdF_2, ZnF_2 and CaF_2 thin films have been obtained successfully with annealing. Thin film electroluminescence (EL) device using these materials, as the host, was fabricated, and the emission has been observed from the rare earth ions or Mn ion. These spectral lines were dominant in the shorter wavelength region compared with that of ZnS-based EL device.

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A value of luminance of EL(electroluminescent) devices have not been reached to suficient at this stage. To overcome that, ZnS:TbF_3 thin films were observed using TEM and X-ray diffraction. Strcture of TbF_3 was investigated. Accordingly the following results are obtained, (1) Tb atoms or particles disturb the formation of recrystalization of ZnS film. (2) The structure of TbF_3 belongs to YF_3 type orthorhombic system.

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ZnS:Tm or SrS:Ce has been used as EL emitting material for full color EL display panels. The luminance of ZnS:Tm thin film EL device is weak despite its good chromaticity. unlike SrS:Ce thin film EL device which has relatively a higher luminance with poor chromaticity. In order to improve the luminance of ZnS:Tm thin film EL devices, the effects f S+ charge compensations due to a Tm^<3+> ion were investigated when the Tm ion was incorporated into the ZnS matrix. The luminance increases when Ag, Cu or P was used as a charge compensator. Ag was the most effective element for the improvement of luminance among those compensators. Further. when equal contents of Ag and Tm were added into the ZnS. an improvement of crystallivity of a ZnS:Tm, F, Ag thin film was observed. and this film enhances the blue emission with suppressing the near infrared emission.

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SrSe:Ce thin fills are expected to be effective for blue-emitting thin fill electroluminescent device with good chromaticity. SrSe and SrSe:Ce thin fills have been prepared by multi-source deposition techniqe, and their structural and luminescent properties have been investigated. When the rate of Sr atoms to Se arriving at the substrate is kept at 1:3, the stoichiometric SrSe fill is obtained. The structural properties are also sensitive to the substrate temperature. The SrSe fills prepared at lower than 400℃ show [100] orientation and the orientation deteriorates gradually at higher than 400℃. On the other hand, the crystallinity is improuved with increasing substrate temperature. Both photoluminescent spectra of SrSe:Ce and electroluminescent spectra of EL devices with SrSe:Ce as emitting layer show the blue emission with peak at about 470nm, whereas these spectra shifts toward longer wavelength with increasing Ce concentration.

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The multi-source depostion method (MSD) using H_2S gas source was proposed to overcome problems caused by using sulfur source. Crystallinity and composition of SrS:CeCl_3 phosphor film prepared by this technique was analyzed. Deposited films was confirmed to have the (200) preferential orientation and to be stoichiometry. Characteristics of electroluminescent (EL) devices with phosphors prepared by MSD using H_2S and effects of insulating materials were investigated. EL devices with SiAlON films as first insulating layers were confirmed to have high luminance, which probably resulted from the smaller change of dielectric loss of SiAlON to the heat treatment compared to the other dielectric materials.

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Thin-film electroluminescent (EL) displays have been extensively investigated because of their many advantages, such as high brightness, rigidness and high viewability. There is an intense demand for a full-color EL display panel. SrS:CeCl_3 is one of the candidates of blue-emitting EL phosphors. Some models had been proposed for explanations of EL characteristics of SrS:Ce EL devices, however, details have not been clear yet. We proposed a model on the basis of formation of shallow interface states induced by oxygen contamination, the dependence of distribution function of interface states on insulator materials and the accumulation of positive space charge induced by ionization of Ce activators. This model was proved to be able to explain the particular characteristics of SrS:Ce EL devices.

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Hot-carrier-injection (HCI) type electroluminescent (EL) devices which have a ZnS carrier acceleration layer and Y_2O_3:Eu or Y_2O_2S:Eu light emitting layers were fabricated, and EL excitation mechanism was investigated. It is supposed that the same carrier transfer as which in conventional double insulated type EL is occurred, 90% of injected carriers are lost excitable energy within 13 nm penetration depth into light emitting layer and penetration depth is modulated by applied device voltage.

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Electrical characteristics of the ZnS:Mn thin-film EL devices, such as Q-V and I-V curves, have been investigated, Capacitance of the EL device, insulating layer and phosphor layer was evaluated by using Q-V and I-V curves. As a drive voltage, sinusoidal, triangular and pulse waveforms were used. The capacitance evaluated by using sinusoidal and triangular waveforms agreed each other. It is shown that in the case of triangular waveforms, I-V characteristic is equivalent to C-V characteristic because dV/dt is constant. On the contrary, in the case of pulse voltage excitation, an evaluation error is relatively large, and a certain value was not obtained. By using an equivalent circuit of the thin-film EL device, SPICE simulation has been performed. The simulated results of Q-V and I-V characteristics agreed qualitatively with the observed results.

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