Tetsuya Shirai

Electroluminescent Devices with Ga2O3:Mn Thin-Film Emitting Layer Prepared by Sol-Gel Process.

High-luminance electroluminescent devices have been newly developed using a Ga2O3:Mn thin film prepared by a sol-gel process. The sol-gel process, which eliminates the need for vacuum processes, enabled the inexpensive preparation of Ga2O3:Mn thin films on large-area thick ceramic sheet insulators. Gallium acethylacetonate, a relatively inexpensive and easy to handle material, was used as the Ga source material. Thin-film electroluminescent (TFEL) devices with a Ga2O3:Mn thin-film emitting layer prepared by the sol-gel process at a deposition temperature of 900°C and a postannealing temperature of 1000°C exhibited luminances of 1271 and 401 cd/m2 when driven at 1 kHz and 60 Hz, respectively.

Mn-Activated Y2O3–GeO2 Phosphors for Thin-Film Electroluminescent Devices

A new multicomponent oxide phosphor, Mn-activated Y2O3–GeO2, is demonstrated to be very promising as the thin-film emitting layer for thin-film electroluminescent (TFEL) devices. High-luminance yellow emissions were obtained in TFEL devices using (Y2O3–GeO2):Mn thin films prepared with a GeO2 content of 0 to 100 mol%: 1756, 2500, 758 and 1629 cd/m2 in 1-kHz-driven TFEL devices fabricated using Y2O3:Mn, Y4GeO8:Mn, Y2GeO5:Mn and Y2Ge2O7:Mn phosphor thin films, i.e., a GeO2 content of 0, 33, 50 or 67 mol%, respectively. In addition, high luminous efficiencies of 2.8, 3.4, 1.5 and 4.5 lm/W, respectively, were obtained in these TFEL devices using a driving voltage at 60 Hz.

High-Luminance Thin Film Electroluminescent Devices Using Monoclinic Y2O3 Phosphor Activated with Mn

A new Mn-activated yttria (Y2O3:Mn) phosphor with a high luminous efficiency was developed using monoclinic Y2O3 as the host material. The monoclinic Y2O3:Mn phosphor thin films were prepared on substrates at a temperature of below approximately 400°C and postannealed at a temperature of approximately 1020°C in Ar atmosphere. Luminances of 7440 and 538 cd/m2 and luminous efficiencies of 1.1 and 10.1 lm/W for yellow emission were obtained for a thin-film electroluminescent device fabricated using monoclinic Y2O3:Mn phosphor and driven at 1 kHz and 60 Hz, respectively.

(Y2O3-GeO2) phosphor thin-film electroluminescent emitting layers prepared by magnetron sputtering

Abstract In this paper, new multicomponent oxides are shown to be promising as a host material for the phosphor thin-film emitting layer of thin-film electroluminescent (TFEL) devices. Mn-activated (Y 2 O 3 –GeO 2 ) multicomponent oxide phosphor thin films were prepared by r.f. magnetron sputtering and used as the emitting layer of TFEL devices. High luminance multicolor emissions were obtained in TFEL devices using (Y 2 O 3 –GeO 2 ):Mn thin films prepared with a GeO 2 content of 0–100 mol.%. In a yellow emitting TFEL device fabricated using a Y 2 GeO 5 phosphor thin film prepared with a GeO 2 content of approximately 50 mol.%, a high luminance of 758 cd/m 2 and a luminous efficiency of 1.4 lm/W were obtained when driven by a sinusoidal wave voltage at 1 kHz.

A new thin-film phosphor using multicomponent oxides composed of Y2O3 and GeO2

The luminescent characteristics of new multicomponent oxide (Y 2 O 3 -GeO 2 ):Mn thin films prepared by r.f. magnetron sputtering are described. High-luminance yellow emissions were obtained in photoluminescence (PL) and electroluminescence using (Y 2 O 3 -GeO 2 ):Mn thin films prepared with a GeO 2 content of 5-84 mol%. It was found that the GeO 2 content dependence of luminance obtained in (Y 2 O 3 -Ge 2 O 7 ):Mn thin-film electroluminescent (TFEL) devices was similar to that of PL intensity as well as the crystallinity of the thin-film emitting layers used in the devices. A luminance of 7700 cd/m 2 was obtained in 1-kHz-driven TFEL devices using (Y 2 O 3 -Ge 2 O 7 ):Mn thin films prepared with a GeO 2 content of 40 mol5.

Fabrication of oxide phosphor thin film electroluminescent devices using a sol-gel process

Thick-insulating-ceramic-type thin-film electroluminescent (TFEL) devices with an oxide phosphor thin-film emitting layer have been fabricated by a sol-gel process that uses various source materials and eliminates the need for vacuum processes. The oxide phosphor thin-film emitting layer consisted of host materials such as Ga2O3, SnO2, ZnGa2O4 and (Ga2O3-Al2O3) multicomponent oxides activated with a transition metal element such as Mn and Cr or a rare earth element such as Eu. High luminances were obtained in TFEL devices with a Ga2O3:Mn, Ga2O3:Cr, SnO2:Eu, ZnGa2O4:Mn or (Ga2O3-Al2O3):Mn phosphor thin-film emitting layer. Luminances above 400 cd/m2 were obtained in green-emitting TFEL devices using Ga2O3:Mn thin films prepared by the sol-gel process, irrespective of source materials, when driven at 60 Hz. It was found that the EL characteristics of oxide phosphor TFEL devices improved as the driving frequency was increased from 60 Hz to 1 kHz. In a Mn- and Cr-co-doped Ga2O3 phosphor TFEL device, an emission color change from green to red as well as high luminances above 100 cd/m2 were obtained when driven at 10 kHz.

Red Emitting Electroluminescent Devices Using Ga 2 O 3 Phosphor Thin Films Prepared by Sol-Gel Process

High-luminance red-emitting thin-film electroluminescent (TFEL) devices have been developed using Ga 2 O 3 phosphor thin films prepared by a sol-gel deposition method. Single-insulating-layer-type TFEL devices were fabricated by depositing a Cr- or a Eu-activated Ga 2 O 3 phosphor thin film onto a thick BaTiO 3 ceramic sheet insulator. The Ga 2 O 3 :Cr or Ga 2 O 3 :Eu thin-film emitting layer was prepared by a sol-gel process using gallium acethylacetonate (Ga(C 5 H 7 O 2 ) 3 ) as the Ga source with Cr(C 5 H 7 O 2 ) 3 or EuC1 3 as the dopant source, respectively. A high red luminance of 622 cd/m 2 was obtained for a Ga 2 O 3 :Cr TFEL device driven by a sinusoidal wave voltage at 1 kHz.