TFEL element with tantalum oxide and tungsten oxide insulating layer

• US 5,404,075 A
• Filed: 10/22/1992
• Issued: 04/04/1995
• Est. Priority Date: 12/26/1991
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation), Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation)
• Inventors: Fujikawa, Hisayoshi, Taga, Yasunori
• Primary Examiner(s): Gross, Anita Pellman
• Assistant Examiner(s): MALINOWSKI, WALTER J
• Application Number:
  US07/964,965
• Time in Patent Office: 894 Days
• Field of Search: 313/502, 313/503, 313/506, 313/507, 313/509, 428/426, 156/252, 252/63.2
• US Class Current: 313/509
• CPC Class Codes: C09K 11/7702 with zinc or cadmium
• CPC Class Codes: C09K 11/7745 with zinc or cadmium
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source
• CPC Class Codes: H05B 33/22 characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers

Abstract

A thin film EL element includes a pair of electrodes disposed oppositely each other, a pair of insulator layers disposed between the electrodes, at least one of the insulator layers consisting essentially of tantalum oxide (Ta₂ O₅) and at least one oxide selected from the group consisting of yttrium oxide (Y₂ O₃) and tungsten oxide (WO₃), and a luminous layer held between the insulator layers. The EL element can be operated at high luminance with only a minimum low voltage required for such an operation. Further, the EL element makes long-lived, stable, etc. display devices. Furthermore, the EL element can be produced by a simplified manufacturing process.

Claims

1. A thin film electroluminescent (EL) element, comprising:

a pair of electrodes disposed oppositely each other;

a pair of insulator layers disposed between said electrodes, at least one of the insulator layers consisting essentially of tantalum oxide (Ta₂ O₅) and tungsten oxide (WO₃), wherein tungsten is present in an amount of less than 15 atomic % with respect to the sum of tantalum and tungsten therein taken as 100 atomic %; and

a luminous layer held between said insulator layers containing a compound including at least a combination of a group II element and a group VI element of the Periodic Table with a rare earth element added as luminous centers.

2. The thin film EL element according to claim 1, wherein at least one, of said insulator layers includes tungsten in an amount of 2 to 4 atomic % with respect to the sum of tantalum and tungsten therein taken as 100 atomic %.

3. The thin film EL element according to claim 1, wherein at least one of said insulator layers has a thickness of 0.2 to 2.0 micrometers.

4. The thin film EL element according to claim 3, wherein at least one of said insulator layers has a thickness of 0.3 to 1.0 micrometer.

5. The thin film EL element according to claim 1, wherein said luminous layer includes zinc sulfide (ZnS) doped with terbium (Tb).

6. The thin film EL element according to claim 5, wherein said luminous layer has a thickness of 0.5 to 1 micrometer.

7. The thin Film EL element according to claim 1, wherein said luminous layer includes zinc sulfide (ZnS) doped with praseodymium (Pr).

8. The thin film EL element according to claim 7, wherein said luminous layer has a thickness of 0.5 to 1 micrometer.