Oxides can be formed from many materials by air sintering after coating a substrate with a metal-organic decomposition (MOD) solution. This enables the preparation of thin films by simple processes such as spin coating. The up-conversion (UC) phosphor produced by the MOD method has a multifunctional potential for use in applications such as displays and solid-state lighting. In this study, a simple TiO 2 -ZnO mixed oxide system was examined for use as the base material and host crystal of rare-earth (RE) elements for UC phosphor. The maximum emission luminescence of the UC phosphor was obtained when the mixing ratios of the base materials TiO 2 : ZnO and additive materials Yb 2 O 3 : Er 2 O 3 were 1 : 1 and 0:06 : 0:06, respectively. When the mixing ratio of the phosphor, Ti : Zn : Yb : Er, was 1 : 1 : 0:06 : 0:06, 550 nm green and 650 nm red emissions were produced. The UC emission intensity could be controlled by varying the mixing ratio of the rare-earth materials.
The metal organic decomposition (MOD) method enables the coating of any oxide material via atmospheric baking of a solution applied to a substrate and enables the fabrication of thin films via simple processes such as using spin coaters. We used titanium oxide, zinc oxide (ZnO), ytterbium oxide, and erbium oxide as MOD solutions. We mixed Ti, Zn, Yb, and Er at arbitrary mixing ratios, applied them on substrates, and then heated them at 1000°C for 4 h under atmosphere. We found that the maximum value for luminance of the upconversion (UC) scintillator can be obtained with mixture ratios of the base material Ti : Zn = 1 : 1 and Yb : Er additives = 0.06 : 0.02. When Yb : Er ratios were from 1:3 to 3:1, a 550 nm green light and 650 nm red light were observed. Moreover, by varying the mixture ratio of RE elements, the UC emission intensity can be controlled. As a result, the UC scintillators produced via the MOD method show the potential for use as multi-functional materials in displays and solid-state illumination.
In this paper, we report on the luminescence (emission) characteristics of a laminated dispersion-type inorganic electroluminescent (EL) device with a nanostripe electrode made of thin Al film, instead of a conventional indium–tin oxide (ITO) transparent electrode, on the emission side of the device. The transmittance of the Al nanostripe electrode, with 60-nm line-and-space widths, was 45%. We compared an inorganic EL device positioned between two thin films of Al and the inorganic EL device with the Al nanostripe electrode using electric field simulations and actual experiments. We were able to apply the same electric field intensity to the phosphor layer in the conventional structure and to the new structure. Therefore, with an Al nanostripe electrode on one side of the EL device, it is possible to fabricate an ITO-free display.
We deposited comb electrodes with narrow gaps between the teeth on a glass substrate, thus realizing a high electric field intensity that cannot be achieved with conventional structures. Au electrodes are deposited to form a comb shape and then spin-coated with a phosphor layer obtained by mixing ZnS phosphor particles with resins in a certain ratio. An AC voltage was applied to the gaps between the teeth of the comb electrode to emit light, from which the luminance was measured for different electric field intensities. The luminance was not affected by the transmittance of the electrodes themselves when measured from the phosphor layer side. Therefore, it may be possible to produce a display that does not require transparent electrodes by using the phosphor layer side of a device with comb electrodes made of metals, such as Au, for the display.
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