Light emitting device with reflective layer including filler particles

• US 9,640,783 B2
• Filed: 09/04/2015
• Issued: 05/02/2017
• Est. Priority Date: 09/17/2014
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Yamana, Masahito, Konda, Tetsushi, Okuno, Tatsuya
• Primary Examiner(s): Tran, Minh-Loan
• Assistant Examiner(s): KHAN, FARID H
• Application Number:
  US14/846,663
• Publication Number:
  US 20160079479A1
• Time in Patent Office: 606 Days
• CPC Class Codes: H10K 50/854 comprising scattering means
• CPC Class Codes: H10K 50/856 comprising reflective means
• CPC Class Codes: H10K 50/858 comprising refractive means, e.g. lenses

Abstract

A light-emitting device according to an aspect of the present disclosure includes a light transmissive first electrode layer, a light transmissive second electrode layer, an electroluminescent layer between the first electrode layer and the second electrode layer, and a reflective layer located on a side opposite to the electroluminescent layer with respect to the second electrode layer. The reflective layer includes a base material having a refractive index equal to or higher than a refractive index of the electroluminescent layer, and fillers each having a refractive index different from that of the base material.

Claims

1. A light-emitting device comprising:

a first electrode layer having light transmissivity;

a second electrode layer opposed to the first electrode layer, the second electrode layer having light transmissivity;

an electroluminescent layer between the first electrode layer and the second electrode layer;

a reflective layer located on a side opposite to the electroluminescent layer with respect to the second electrode layer;

a low reflectance layer between the electroluminescent layer and the reflective layer, the low reflectance layer having a refractive index that is 95% or more and less than 100% of the refractive index of the electroluminescent layer; and

a light extraction layer located on a side opposite to the electroluminescent layer with respect to the first electrode layer, wherein

the reflective layer includes

a base material having a refractive index equal to or higher than a refractive index of the electroluminescent layer, and

filler particles each having a refractive index different from a refractive index of the base material, and

the base material includes a matrix and auxiliary filler particles.

2. The light-emitting device according to claim 1, wherein

a refractive index of the second electrode layer is equal to or higher than the refractive index of the electroluminescent layer.

3. The light-emitting device according to claim 1, further comprising:

a substrate located on a side opposite to the electroluminescent layer with respect to the first electrode layer.

4. The light-emitting device according to claim 1, wherein

the filler particles each have the refractive index lower than the refractive index of the base material.

5. The light-emitting device according to claim 1, wherein

the filler particles each have the refractive index higher than the refractive index of the base material.

6. The light-emitting device according to claim 1, wherein

an average particle diameter of the filler particles is 0.1 μ

m or more and 10 μ

m or less.

7. The light-emitting device according to claim 1, wherein

the auxiliary filler particles have a higher refractive index than the matrix, and

an average particle diameter of the auxiliary filler particles is 0.005 μ

m or more and 0.05 μ

m or less.

8. A light-emitting device comprising:

a first electrode layer having light transmissivity;

a second electrode layer opposed to the first electrode layer, the second electrode layer having light transmissivity;

an electroluminescent layer between the first electrode layer and the second electrode layer and emitting light;

a reflective layer located on a side opposite to the electroluminescent layer with respect to the second electrode layer and diffusely reflecting the light; and

a low-refractive index layer between the electroluminescent layer and the reflective layer, the low-refractive index layer having a lower refractive index than the electroluminescent layer, wherein

the reflective layer includes;

a base material having a refractive index equal to or higher than the refractive index of the low-refractive index layer, and

filler particles each having a refractive index different from the refractive index of the base material, and

the base material includes a matrix and auxiliary filler particles.

9. The light-emitting device according to claim 8, wherein

the low-refractive index layer transmits part of the light and reflects other part of the light on a surface thereof on a side of the electroluminescent layer.

10. The light-emitting device according to claim 8, wherein

the low-refractive index layer is located between the reflective layer and the second electrode layer.

11. The light-emitting device according to claim 8, further comprising:

a light extraction layer located on a side opposite to the reflective layer with respect to the low-refractive index layer.

12. The light-emitting device according to claim 11, wherein

the light extraction layer is located between the second electrode layer and the low-refractive index layer.

13. The light-emitting device according to claim 11, further comprising:

a substrate located on a side opposite to the electroluminescent layer with respect to the first electrode layer, wherein

the light extraction layer is located between the substrate and the first electrode layer.

14. The light-emitting device according to claim 11, wherein

the light extraction layer is in contact with the low-refractive index layer.

15. The light-emitting device according to claim 8, wherein

the thickness of the low-refractive index layer is 1 μ

m or more and 1 mm or less.

16. The light-emitting device according to claim 8, wherein

the low-refractive index layer includes an air layer.

17. The light-emitting device according to Claim 8, wherein

an average particle diameter of the fillers filler particles is 0.1 μ

m or more and 10 μ

m or less.

18. The light-emitting device according to Claim 8, wherein

the base material includes a matrix and auxiliary filler particles having a higher refractive index than the matrix, and

an average particle diameter of the auxiliary filler particles is 0.005 μ

m or more and 0.05 μ

m or less.