Electroluminescence Light Source

• US 20080197764A1
• Filed: 05/03/2006
• Published: 08/21/2008
• Est. Priority Date: 05/12/2005
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Bechtel, Helmut, Greiner, Horst
• Application Number:
  US11/913,876
• Publication Number:
  US 20080197764A1
• Time in Patent Office: Days
• US Class Current: 313/499
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H10K 50/854 comprising scattering means
• CPC Class Codes: H10K 50/856 comprising reflective means

Abstract

Electroluminescence light source having a transparent substrate (2), an electroluminescent layer structure for emitting light throughthe substrate, a first light outcoupling layer (3) arranged between substrate and electroluminescent layer structure for producing a non-uniform angular distribution of the light upon entry of the light into the substrate (2), and a second light outcoupling layer (1) arranged above the substrate (2) when viewed in the direction of propagation of light (7), with a surface structure adapted to the non-uniform angular distribution of the light for the effective light outcoupling from the electroluminescence light source.

Claims

1. An electroluminescence light source having a transparent substrate (2), an electroluminescent layer structure for emitting light through the substrate, a first light outcoupling layer (3) arranged between substrate and electroluminescent layer structure for producing a non-uniform angular distribution of the light upon entry ofthe light into the substrate (2), and a second light outcoupling layer (1) arranged above the substrate (2) when viewed in the direction of propagation of light (7), with a surface structure adapted to the non-uniform angular distribution of the light for the effective light outcoupling from the electroluminescence light source.

2. An electroluminescence light source as claimed in claim 1, characterized in that the non-uniform angular distribution has a maximum and an angle range of ±

15 degrees around said maximum comprises more than 70% of the light (11), preferably more than 80% of the light (11), particularly preferably more than 90% of the light (11).

3. An electroluminescence light source as claimed in claim 1, characterized in that the maximum of the non-uniform angular distribution lies at an angle larger than 45 degrees, preferably larger than 60 degrees, particularly preferably larger than 75 degrees.

4. An electroluminescence light source as claimed in claim 1, characterized in that the first light outcoupling layer (3) has a thickness H₂ between 100 nm and 10 μ

m.

5. An electroluminescence light source as claimed in claim 1, characterized in that the first light outcoupling layer (3) comprises at least a first material (9) and a second material (10).

6. An electroluminescence light source as claimed in claim 5, characterized in that the first material (9) has a refractive index n₁, the second material (10) a refractive index n₂ and the difference between the refractive indices n₁, and n₂ lies between 0.1 and 2.5.

7. An electroluminescence light source as claimed in claim 5, characterized in that the first material (9) is arranged in the second material (10), essentially in a periodic structure of a multiplicity of structural elements, in a plane parallel to the surface of the first light outcoupling layer(3), which structural elements are designed as spatial bodies, comprising spherical, cylindrical, pyramidal, cubical or ellipsoid bodies.

8. An electroluminescence light source as claimed in claim 7, characterized in that the structural elements, viewed in the direction of propagation of light, have a height H₁ and the thickness H₂ of the first light outcoupling layer (3) has a value between H₁ and 10*H₁.

9. An electroluminescence light source as claimed in claim 7 , characterized in that at a total number N of the structural elements, a distance a_i between two neighboring structural elements can deviate from an average distance a₀ and the distribution n(a_i) of the distances a_i fits the formula

$n$

( a i ) = N a i 

s 

2 



π



exp 

[ - ln 2 

( a i / a 0 ) 2 



s 2 ]

wherein 0<

s<

0.4.

10. An electroluminescence light source as claimed in claim 1, characterized in that the surface structure (8) of the second light outcoupling layer (1) comprises square pyramidal structures, triangular pyramidal structures, hexagonal pyramidal structures, ellipsoid dome structures or cone structures.

11. An electroluminescence light source as claimed in claim 1, characterized in that the height H_r of the surface structure (8) of the second light outcoupling layer (1) in the direction of propagation of light (7) is larger than 10 μ

m and smaller than 5-fold the substrate thickness.

12. An electroluminescence light source as claimed in claim 1, characterized in that the second light outcoupling layer (1) has a refractive index larger than or equal to that of the substrate (2) and smaller than 3.