LIGHT-EMITTING DEVICE, ILLUMINATION APPARATUS, AND DISPLAY APPARATUS

• US 20110187259A1
• Filed: 01/19/2011
• Published: 08/04/2011
• Est. Priority Date: 01/29/2010
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: FUKUDA, Toshihiro, YAMADA, Jiro, EBIHARA, Yohei
• Granted Patent: US 8,227,981 B2
• Time in Patent Office: Days
• US Class Current: 313/114
• CPC Class Codes: H01K 1/26 Screens; Filters associated with envelope H01K1/28
• CPC Class Codes: H10K 50/19 Tandem OLEDs
• CPC Class Codes: H10K 50/852 comprising a resonant cavity structure, e.g. Bragg reflector pair
• CPC Class Codes: H10K 59/876 comprising a resonant cavity structure, e.g. Bragg reflector pair

Abstract

A light-emitting device including: an organic layer which is interposed between a first electrode and a second electrode and in which a first light-emitting layer and a second light-emitting layer emitting light of single colors or two or more different colors in a visible wavelength region are sequentially included at mutually separated positions in that order in a direction from the first electrode to the second electrode; a first reflective interface which is provided on the side of the first electrode so as to reflect light emitted from the first light-emitting layer and the second light-emitting layer to be emitted from the side of the second electrode; and a second reflective interface and a third reflective interface which are sequentially provided on the side of the second electrode at mutually separated positions in that order in a direction from the first electrode to the second electrode.

Claims

1. A light-emitting device comprising:

an organic layer which is interposed between a first electrode and a second electrode and in which a first light-emitting layer and a second light-emitting layer emitting light of single colors or two or more different colors in a visible wavelength region are sequentially included at mutually separated positions in that order in a direction from the first electrode to the second electrode;

a first reflective interface which is provided on the side of the first electrode so as to reflect light emitted from the first light-emitting layer and the second light-emitting layer to be emitted from the side of the second electrode; and

a second reflective interface and a third reflective interface which are sequentially provided on the side of the second electrode at mutually separated positions in that order in a direction from the first electrode to the second electrode,

wherein an optical distance between the first reflective interface and a luminescent center of the first light-emitting layer is set so that light having a central wavelength of an emission spectrum of the first light-emitting layer is reinforced through interference between the first reflective interface and the luminescent center of the first light-emitting layer,

wherein an optical distance between the first reflective interface and a luminescent center of the second light-emitting layer is set so that light having a central wavelength of an emission spectrum of the second light-emitting layer is reinforced through interference between the first reflective interface and the luminescent center of the second light-emitting layer, and

wherein the reflection of light by the second reflective interface and the reflection of light by the third reflective interface occur so that light having wavelengths shifted by an amount of +15 nm or more and −

15 nm or less from at least one of the central wavelength of the emission spectrum of the first light-emitting layer and the central wavelength of the emission spectrum of the second light-emitting layer is weakened.

2. The light-emitting device according to claim 1, wherein when the optical distance between the first reflective interface and the luminescent center of the first light-emitting layer is L11, the optical distance between the first reflective interface and the luminescent center of the second light-emitting layer is L21, an optical distance between the luminescent center of the first light-emitting layer and the second reflective interface is L12, an optical distance between the luminescent center of the second light-emitting layer and the second reflective interface is L22, an optical distance between the luminescent center of the first light-emitting layer and the third reflective interface is L13, an optical distance between the luminescent center of the second light-emitting layer and the third reflective interface is L23, the central wavelength of an emission spectrum of the first light-emitting layer is λ

1, and the central wavelength of an emission spectrum of the second light-emitting layer is λ

2, L11, L21, L12, L22, L13, and L23 are chosen so as to satisfy all the expressions (1) to (8) and at least one of the expressions (9) and (10).

2L11/λ

11+φ

1/2π

=m 

 

(1)

2L21/λ

21+φ

1/2π

=n (where n≧

m+1) 

 

(2)

2L12/λ

12+φ

2/2π

=m′

+1/2 

 

(3)

2L22/λ

22+φ

2/2π

=n′

+1/2 

 

(4)

2L13/λ

13+φ

3/2π

=m″

+1/2 

 

(5)

2L23/λ

23+φ

3/2π

=n″

+1/2 

 

(6)

λ

1−

30<

λ

11<

λ

1+80 

 

(7)

λ

2−

30<

λ

21<

λ

2+80 

 

(8)

λ

12≦

λ

1−

15 and λ

13≧

λ

1+15, or

λ

13≦

λ

1−

15 and λ

12≧

λ

1+15 

 

(9)

λ

22≦

λ

2−

15 and λ

23≧

λ

2+15, or

λ

23≦

2−

15 and λ

22≧

λ

2+15 

 

(10)

where m, m′

, m″

, n, n′

, n″

are integers,

λ

1, λ

2, λ

11, λ

21, λ

12, λ

22, λ

13, and λ

23 are in units of nm,

φ

1 is a phase shift occurring when light of each wavelength is reflected by the first reflective interface,

φ

2 is a phase shift occurring when light of each wavelength is reflected by the second reflective interface, and

φ

3 is a phase shift occurring when light of each wavelength is reflected by the third reflective interface.

3. The light-emitting device according to claim 2, wherein peaks of a spectral transmittance curve of an interference filter of the light-emitting device are substantially flat, or the slopes thereof are substantially the same in the wavelength range of all emission colors.

4. The light-emitting device according to claim 3, wherein a decrease of luminance at a viewing angle of 45°

is 30% or less with respect to luminance at a viewing angle of 0°

, and a chromaticity shift of Δ

uv≦

0.015 is obtained.

5. The light-emitting device according to claim 4, wherein a difference between the wavelengths of the light of two or more different colors is within 120 nm.

6. The light-emitting device according to claim 5, wherein m=0 and n=1.

7. The light-emitting device according to claim 1, wherein the first electrode, the organic layer, and the second electrode are sequentially stacked on a substrate.

8. The light-emitting device according to claim 7, wherein a transparent electrode layer having a thickness of 1 μ

m or more, a transparent insulating layer, a resin layer, a glass layer, or an air layer is formed on an outer side of the third reflective interface.

9. The light-emitting device according to claim 1, wherein the second electrode, the organic layer, and the first electrode are sequentially stacked on a substrate.

10. The light-emitting device according to claim 9, wherein a transparent electrode layer having a thickness of 1 μ

m or more, a transparent insulating layer, a resin layer, a glass layer, or an air layer is formed on an outer side of the third reflective interface.

11. The light-emitting device according to claim 1, wherein a metal layer having a thickness of 5 nm or less is formed between the second light-emitting layer and the second electrode.

12. The light-emitting device according to claim 1, wherein at least one of the first reflective interface, the second reflective interface, and the third reflective interface is divided into a plurality of reflective interfaces.

13. The light-emitting device according to claim 1, wherein when the luminescent centers of light-emitting layers of the first or second light-emitting layer emitting light of two or more different colors may not be regarded as identical, the light-emitting device further includes a reflective layer which is provided so as to maintain the flatness of the peaks of a spectral transmittance curve of an interference filter of the light-emitting device.

14. An illumination apparatus comprising:

at least one light-emitting device,

wherein the light-emitting device includes

an organic layer which is interposed between a first electrode and a second electrode and in which a first light-emitting layer and a second light-emitting layer emitting light of single colors or two or more different colors in a visible wavelength region are sequentially included at mutually separated positions in that order in a direction from the first electrode to the second electrode;

a first reflective interface which is provided on the side of the first electrode so as to reflect light emitted from the first light-emitting layer and the second light-emitting layer to be emitted from the side of the second electrode; and

a second reflective interface and a third reflective interface which are sequentially provided on the side of the second electrode at mutually separated positions in that order in a direction from the first electrode to the second electrode,

wherein an optical distance between the first reflective interface and a luminescent center of the first light-emitting layer is set so that light having a central wavelength of an emission spectrum of the first light-emitting layer is reinforced through interference between the first reflective interface and the luminescent center of the first light-emitting layer,

wherein an optical distance between the first reflective interface and a luminescent center of the second light-emitting layer is set so that light having a central wavelength of an emission spectrum of the second light-emitting layer is reinforced through interference between the first reflective interface and the luminescent center of the second light-emitting layer, and

wherein the reflection of light by the second reflective interface and the reflection of light by the third reflective interface occur so that light having wavelengths shifted by an amount of +15 nm or more and −

15 nm or less from at least one of the central wavelength of the emission spectrum of the first light-emitting layer and the central wavelength of the emission spectrum of the second light-emitting layer is weakened.

15. A display apparatus comprising:

at least one light-emitting device,

wherein the light-emitting device includes

an organic layer which is interposed between a first electrode and a second electrode and in which a first light-emitting layer and a second light-emitting layer emitting light of single colors or two or more different colors in a visible wavelength region are sequentially included at mutually separated positions in that order in a direction from the first electrode to the second electrode;

a first reflective interface which is provided on the side of the first electrode so as to reflect light emitted from the first light-emitting layer and the second light-emitting layer to be emitted from the side of the second electrode; and

a second reflective interface and a third reflective interface which are sequentially provided on the side of the second electrode at mutually separated positions in that order in a direction from the first electrode to the second electrode,

wherein an optical distance between the first reflective interface and a luminescent center of the first light-emitting layer is set so that light having a central wavelength of an emission spectrum of the first light-emitting layer is reinforced through interference between the first reflective interface and the luminescent center of the first light-emitting layer,

wherein an optical distance between the first reflective interface and a luminescent center of the second light-emitting layer is set so that light having a central wavelength of an emission spectrum of the second light-emitting layer is reinforced through interference between the first reflective interface and the luminescent center of the second light-emitting layer, and

wherein the reflection of light by the second reflective interface and the reflection of light by the third reflective interface occur so that light having wavelengths shifted by an amount of +15 nm or more and −

15 nm or less from at least one of the central wavelength of the emission spectrum of the first light-emitting layer and the central wavelength of the emission spectrum of the second light-emitting layer is weakened.

16. The display apparatus according to claim 15, further comprising:

a driving substrate on which an active device is provided so as to supply a display signal corresponding to every display pixel to the light-emitting device; and

a sealing substrate provided so as to face the driving substrate,

wherein the light-emitting device is disposed between the driving substrate and the sealing substrate.

17. The display apparatus according to claim 16, wherein a color filter which transmits light emitted from the side of the second electrode is provided on a substrate that is disposed on the side of the second electrode of the light-emitting device among the driving substrate and the sealing substrate.