Light-emitting element and organic electroluminescent display device

1. A light-emitting element, comprising:

(A) a first electrode;

(B) an organic layer including a light-emitting layer made of an organic light-emitting material;

(C) a semi-transmissive/reflective film;

(D) a resistance layer; and

(E) a second electrode,

wherein,

the first electrode is configured to reflect light coming from the light-emitting layer,

the second electrode is configured to allow light coming from the semi-transmissive/reflective film after passing therethrough,

the semi-transmissive/reflective film on the organic layer has an average film thickness of 1 nm to 6 nm both inclusive,

the light from the light-emitting layer is made to resonate between (i) a first interface between the first electrode and the organic layer, and (ii) a second interface between the semi-transmissive/reflective film and the organic layer, and

a part of the light is emitted from the semi-transmissive/reflective film.

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

the semi-transmissive/reflective film is made of alloys of magnesium-silver, aluminum, or silver.

3. The light-emitting element according to claim 1 ,

wherein,

a material configuring the resistance layer has an electrical resistivity of 1×10 6 Ωm to 1×10 10 Ωm both inclusive, and

the resistance layer above the organic layer has a thickness of 0.1 μm to 2 μm both inclusive.

4. The light-emitting element according to claim 1 ,

wherein

the first electrode includes a foreign substance or a protrusion,

the semi-transmissive/reflective film is not formed to a region proximal to the foreign substance or the protrusion, and

the resistance layer exists in a region between (i) a portion of the semi-transmissive/reflective film in the periphery of the foreign substance or the protrusion, and (ii) a portion of the first electrode under the foreign substance or beneath the protrusion.

5. The light-emitting element according to claim 1 ,

wherein

when a distance from the first interface being an interface between the first electrode and the organic layer to a position on the light-emitting layer where a level of light emission is maximum is L 1 , an optical distance thereof is OL 1 , a distance from the second interface being an interface between the semi-transmissive/reflective film and the organic layer to the position on the light-emitting layer where a level of light emission is maximum is L 2 , and an optical distance thereof is OL 2 , expressions (1-1) and (1-2) below are satisfied,

0.7{−φ 1 /(2π)+ m 1 }≦2 ×OL 1 /λ≦1.2{−φ 1 /(2π)+ m 1 }  (1-1)

0.7{−φ 2 /(2π)+ m 2 }≦2 ×OL 2 /λ≦1.2{−φ 2 /(2π)+ m 2 }  (1-2)

where λ is a maximum peak wavelength in a spectrum of the light generated in the light-emitting layer,

φ 1 is an amount of phase shift (unit: radian) of a reflected light generated on the first interface (where −2π<φ 1 ≦0)

φ 2 is an amount of phase shift (unit: radian) of a reflected light generated on the second interface (where −2π<φ 2 ≦0), and

a value of (m 1 , m 2 ) is (0, 0), (1, 0), or (0, 1).

6. The light-emitting element according to claim 1 ,

wherein

when an optical distance between the first interface being an interface between the first electrode and the organic layer and the second interface being an interface between the semi-transmissive/reflective film and the organic layer is L, a sum of phase shift to be observed when the light generated in the light-emitting layer is reflected on the first and second interfaces is φ radian [where −2π<φ≦0], and a maximum peak wavelength in a spectrum of the light generated in the light-emitting layer is λ,

an expression of

0.7≦{(2 L )/λ+φ/(2π)}≦1.3

or

−0.3≦{(2 L )/λ+φ/(2π)}≦0.3

is satisfied.

7. A light-emitting element, comprising:

(A) a first electrode;

(B) an organic layer including a light-emitting layer made of an organic light-emitting material;

(C) a semi-transmissive/reflective film;

(D) a resistance layer; and

(E) a second electrode, in this order,

wherein

the first electrode is configured to reflect light coming from the light-emitting layer,

the second electrode is configured to transmitlight coming from the semi-transmissive/reflective film after passing through the semi-transmissive/reflective film, and

when an distance from a first interface between the first electrode and the organic layer to a position on the light-emitting layer where a level of light emission is maximum is L 1 , an optical distance thereof is OL 1 , a distance from a second interface between the semi-transmissive/reflective film and the organic layer to a position on the light-emitting layer where a level of light emission is maximum is L 2 , and an optical distance thereof is OL 2 , expressions (1-1) and (1-2) below are satisfied,

0.7{−φ 1 /(2π)+ m 1 }≦2 ×OL 1 /λ≦1.2{−φ 1 /(2π)+ m 1 }  (1-1)

0.7{−φ 2 /(2π)+ m 2 }≦2 ×OL 2 /λ≦1.2{−φ 2 /(2π)+ m 2 }  (1-2)

where λ is a maximum peak wavelength in a spectrum of a light generated in the light-emitting layer,

φ 1 is an amount of phase shift (unit: radian) of a reflected light generated on the first interface (where −2π<φ 1 ≦0)

φ 2 is an amount of phase shift (unit: radian) of a reflected light generated on the second interface (where −2π<φ 2 ≦0), and

a value of (m 1 , m 2 ) is (0, 0), (1, 0), or (0, 1).

8. A light-emitting element, comprising:

(A) a first electrode;

(B) an organic layer including a light-emitting layer made of an organic light-emitting material;

(C) a semi-transmissive/reflective film;

(D) a resistance layer; and

(E) a second electrode,

wherein

the first electrode reflects a light coming from the light-emitting layer,

the second electrode passes through a light coming from the semi-transmissive/reflective film after passing through the semi-transmissive/reflective film, and

when an optical distance between a first interface between the first electrode and the organic layer and a second interface between the semi-transmissive/reflective film and the organic layer is L, a sum of phase shift to be observed when a light generated in the light-emitting layer is reflected on the first and second interfaces is φ radian [where −2π<φ≦0], and a maximum peak wavelength in a spectrum of the light generated in the light-emitting layer is λ,

an expression of

0.7≦{(2 L )/λ+φ/(2π)}≦1.3

or

−0.3≦{(2 L )/λ+φ/(2π)}≦0.3

is satisfied.

9. An organic electroluminescent display device, including a plurality of organic electroluminescent elements each comprising:

(a) a first electrode;

(b) an insulation layer including an aperture, and from a bottom portion of the aperture, the first electrode is exposed;

(c) an organic layer that is disposed from the above of a portion of the first electrode exposed from the bottom portion of the aperture to a portion of the insulation layer around the aperture, and includes a light-emitting layer made of an organic light-emitting material;

(d) a semi-transmissive/reflective film formed at least on the organic layer;

(e) a resistance layer covering the semi-transmissive/reflective film; and

(f) a second electrode formed on the resistance layer,

wherein

the first electrode reflects a light coming from the light-emitting layer,

the second electrode passes through a light coming from the semi-transmissive/reflective film after passing therethrough, and

a portion of the semi-transmissive/reflective film on the insulation layer is at least partially discontinuous.

10. The organic electroluminescent display device according to claim 9 , wherein

the semi-transmissive/reflective film on the organic layer has an average film thickness of 1 nm to 6 nm both inclusive.

11. The organic electroluminescent display device according to claim 9 , wherein

the semi-transmissive/reflective film is made of alloys of magnesium-silver, aluminum, or silver.

12. The organic electroluminescent display device according to claim 9 ,

wherein

a material configuring the resistance layer has an electrical resistivity of 1×10 6 Ωm to 1×10 10 Ωm both inclusive, and

the resistance layer above the organic layer has a thickness of 0.1 μm to 2 μm both inclusive.

13. The organic electroluminescent display device according to claim 9 ,

wherein

there is a foreign substance or a protrusion

the semi-transmissive/reflective film is not formed to a region proximal to the foreign substance or the protrusion, and

the resistance layer exists in a region between (i) a portion of the semi-transmissive/reflective film in the periphery of the foreign substance or the protrusion, and a (ii) portion of the first electrode under the foreign substance or beneath the protrusion.

14. The organic electroluminescent display device according to claim 9 ,

wherein

a light generated in the light-emitting layer is made to resonate between a first interface between the first electrode and the organic layer and a second interface

a part of the resulting light is emitted from the semi-transmissive/reflective film.

15. The organic electroluminescent display device according to claim 14 ,

wherein

when a distance from the first interface between the first electrode and the organic layer to a position on the light-emitting layer where a level of light emission is maximum is L 1 , an optical distance thereof is OL 1 , a distance from the second between the semi-transmissive/reflective film and the organic layer to a position on the light-emitting layer where a level of light emission is maximum is L 2 , and an optical distance thereof is OL 2 , expressions (1-1) and (1-2) below are satisfied,

0.7{−φ 1 /(2π)+ m 1 }≦2 ×OL 1 /λ≦1.2{−φ 1 /(2π)+ m 1 }  (1-1)

0.7{−φ 2 /(2π)+ m 2 }≦2 ×OL 2 /λ≦1.2{−φ 2 /(2π)+ m 2 }  (1-2)

where λ is a maximum peak wavelength in a spectrum of the light generated in the light-emitting layer,

φ 1 is an amount of phase shift (unit: radian) of a reflected light generated on the first interface (where −2π<φ 1 ≦0)

φ 2 is an amount of phase shift (unit: radian) of a reflected light generated on the second interface (where −2π<φ 2 ≦0), and

a value of (m 1 , m 2 ) is (0, 0), (1, 0), or (0, 1).

16. The organic electroluminescent display device according to claim 14 ,

wherein

when an optical distance between the first interface between the first electrode and the organic layer and the second interface between the semi-transmissive/reflective film and the organic layer is L, a sum of phase shift to be observed when the light generated in the light-emitting layer is reflected on the first and second interfaces is φ radian [where −2π<φ≦0], and a maximum peak wavelength in a spectrum of the light generated in the light-emitting layer is λ,

an expression of

0.7≦{(2 L )/λ+φ/(2π)}≦1.3

or

−0.3≦{(2 L )/λ+φ/(2π)}≦0.3

is satisfied.