Blue-violet phosphor for use in electroluminescent flat panel displays

• US 5,602,445 A
• Filed: 05/12/1995
• Issued: 02/11/1997
• Est. Priority Date: 05/12/1995
• Status: Expired due to Term

• Current Assignee: Oregon Health & Science University
• Original Assignee: Oregon Graduate Institute Of Science And Technology
• Inventors: Kong, Weiran, Ahmed, Shafqat, Solanki, Rajendra
• Primary Examiner(s): Arana, Louis M.
• Assistant Examiner(s): Patel, Vip
• Application Number:
  US08/440,203
• Time in Patent Office: 641 Days
• Field of Search: 313/502, 313/503, 313/505, 313/506, 313/509, 252/301.4 H, 252/301.6 R
• US Class Current: 313/503
• CPC Class Codes: C09K 11/7719 Halogenides C09K11/7716 takes precedence
• CPC Class Codes: C09K 11/772 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/7732 Halogenides
• CPC Class Codes: C09K 11/7733 with alkali or alkaline earth metals
• 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

Abstract

A bright, short wavelength blue-violet phosphor for electroluminescent displays comprises an alkaline-based halide as a host material and a rare earth as a dopant. The host alkaline chloride can be chosen from the group II alkaline elements, particularly strontium chloride (SrCl₂) or calcium chloride (CaCl₂), which, with a europium (Eu) or cerium (Ce) rare earth dopant, electroluminesces at a peak wavelength of 404 and 367 nanometers (nm) respectively. The resulting emissions have CIE chromaticity coordinates which lie at the boundary of the visible range for the human eye thereby allowing a greater range of colors for full color flat panel electroluminescent (FPEL) displays.

Claims

1. A thin film electroluminescent (TFEL) element in a display comprising a transparent substrate, a transparent conducting film defining a first electrode, a first dielectric layer, a luminescent layer, and a second dielectric layer, each layer formed on top of the other on the substrate, the second dielectric layer being provided with a second electrode, the luminescent layer including:

a strontium chloride (SrCl₂) host layer; and

a rare earth dopant.

2. The EL element of claim 1, wherein the rare earth dopant is selected from a group consisting of divalent europium (Eu²⁺) and trivalent cerium (Ce³⁺).

3. A thin film electroluminescent (TFEL) device comprising a front electrode set deposited on a transparent substrate, a rear electrode set, and a thin film laminate sandwiched between said front and rear electrode sets, said thin film laminate including at least a pair of insulating layers sandwiching an alkaline halide phosphor layer having the chemical formula:

space="preserve" listing-type="equation">MCl.sub.2 ;

RE

where M is selected from the group consisting of calcium, strontium, zinc, and barium, and RE comprises a rare earth activator dopant.

4. The device of claim 3 where M is strontium.

5. The device of claim 3 where M is calcium.

6. The device of claim 3 where M is barium.

7. The device of claim 3 where M is zinc.

8. The device of claim 3 where RE is europium.

9. The device of claim 3 where RE is cerium.

10. The device of claim 3 where RE is samarium.

11. The device of claim 3 further including a pair of protective film layers sandwiching the alkaline halide phosphor layer and interposed between the pair of insulating layers.