Light-emitting device
A light-emitting device includes a first reflective surface, a second reflective surface, a light-emitting layer, and a third reflective surface. The second reflective surface faces the first reflective surface. The light-emitting layer is provided between the first reflective surface and the second reflective surface, and outputs light of a wavelength λ. The third reflective surface faces the second reflective surface, and is located at a distance within λ/4 from the second reflective surface.
1. A light-emitting device comprising:
a first reflective surface;
a second reflective surface that faces the first reflective surface;
a light-emitting layer that is provided between the first reflective surface and the second reflective surface, and outputs light of a wavelength λ; and
a third reflective surface that faces the second reflective surface, and is located at a distance within λ/4 from the second reflective surface.
2. The light-emitting device according to claim 1 , further comprising a low refractive index layer and a high refractive index layer that have different refractive indexes and are stacked each other, wherein
the third reflective surface is an interface between the low refractive index layer and the high refractive index layer.
3. The light-emitting device according to claim 1 , wherein
the light-emitting layer includes
a first light-emitting layer, and
a second light-emitting layer provided in a region different from the first light-emitting layer, and
L 11 , L 21 , L 12 , and L 22 satisfy following expressions [1] to [8]:
2 L 11/λ11+ a 1/(2π)= m 1(provided that m 1≥0) [1]
λ1−150<λ11<λ1+80 [2]
2 L 21/λ21+ c 1/(2π)= n 1(provided that n 1≥0) [3]
λ2−150<λ21<λ2+80 [4]
2 L 12/λ12+ a 2/(2π)= m 2 [5]
λ1−80<λ12<λ1+80 [6]
2 L 22/λ22+ c 2/(2π)= n 2 [7]
λ2−80<λ22<λ2+80 [8]
where
L 11 denotes an optical distance from the first reflective surface to a light emission center of the first light-emitting layer,
L 21 denotes an optical distance from the first reflective surface to a light emission center of the second light-emitting layer,
L 12 denotes an optical distance from the second reflective surface to the light emission center of the first light-emitting layer,
L 22 denotes an optical distance from the second reflective surface to the light emission center of the second light-emitting layer,
λ 1 denotes a center wavelength of a light emission spectrum of the first light-emitting layer,
λ 2 denotes a center wavelength of a light emission spectrum of the second light-emitting layer,
m 1 , n 1 , m 2 , and n 2 each denote an integer,
λ 1 , λ 2 , λ 11 , λ 21 , λ 12 , and λ 22 are each in unit of nm,
a 1 denotes a phase change generated upon reflection, at the first reflective surface, of light of each wavelength outputted from the first light-emitting layer,
c 1 denotes a phase change generated upon reflection, at the first reflective surface, of light of each wavelength outputted from the second light-emitting layer,
a 2 denotes a phase change generated upon reflection, at the second reflective surface, of the light of each wavelength outputted from the first light-emitting layer, and
c 2 denotes a phase change generated upon reflection, at the second reflective surface, of the light of each wavelength outputted from the second light-emitting layer.
4. The light-emitting device according to claim 3 , wherein
L 13 and L 23 satisfy following expressions [9] to [12]:
2 L 13/λ13+ a 3/(2π)= m 3+½ [9]
λ1−150<λ13<λ1+150 [10]
2 L 23/λ23+ c 3/(2π)= n 3+½ [11]
λ2−150<λ23<λ2+150 [12]
where
L 13 denotes an optical distance from the third reflective surface to the light emission center of the first light-emitting layer,
L 23 denotes an optical distance from the third reflective surface to the light emission center of the second light-emitting layer,
m 3 and n 3 each denote an integer,
λ 1 , λ 2 , λ 13 , and λ 23 are each in unit of nm,
a 3 denotes a phase change generated upon reflection, at the third reflective surface, of the light of each wavelength outputted from the first light-emitting layer, and
c 3 denotes a phase change generated upon reflection, at the third reflective surface, of the light of each wavelength outputted from the second light-emitting layer.
5. The light-emitting device according to claim 3 , wherein
L 13 and L 23 satisfy following expressions [13] to [16]:
2 L 13/λ13+ a 3/(2π)= m 3 [13]
λ1−150<λ13<λ1+150 [14]
2 L 23/λ23+ c 3/(2π)= n 3 [15]
λ2−150<λ23<λ2+150 [16]
where
L 13 denotes an optical distance from the third reflective surface to the light emission center of the first light-emitting layer,
L 23 denotes an optical distance from the third reflective surface to the light emission center of the second light-emitting layer,
m 3 and n 3 each denote an integer,
λ 1 , λ 2 , λ 13 , and λ 23 are each in unit of nm,
a 3 denotes a phase change generated upon reflection, at the third reflective surface, of the light of each wavelength outputted from the first light-emitting layer, and
c 3 denotes a phase change generated upon reflection, at the third reflective surface, of the light of each wavelength outputted from the second light-emitting layer.
6. The light-emitting device according to claim 1 , further comprising:
a first electrode provided between the first reflective surface and the light-emitting layer; and
a second electrode that faces the first electrode with the light-emitting layer being interposed therebetween.
7. The light-emitting device according to claim 6 , further comprising a substrate, wherein
the first electrode, the light-emitting layer, and the second electrode are provided in order from the substrate.
8. The light-emitting device according to claim 6 , further comprising a substrate, wherein
the second electrode, the light-emitting layer, and the first electrode are provided in order from the substrate.
9. The light-emitting device according to claim 1 , further comprising an organic layer including the light-emitting layer.
10. The light-emitting device according to claim 9 , wherein the light-emitting layer comprises a printed layer.
11. The light-emitting device according to claim 9 , further comprising a high resistance layer that is provided between the organic layer and the second reflective surface, and contains a metal oxide, wherein
the third reflective surface is an interface between the organic layer and the high resistance layer.
12. The light-emitting device according to claim 3 , further comprising:
a fourth reflective surface that faces the light-emitting layer with the second reflective surface being interposed therebetween; and
a fifth reflective surface that faces the second reflective surface with the fourth reflective surface being interposed therebetween.
13. The light-emitting device according to claim 12 , wherein
L 14 and L 15 satisfy following expressions [17] to [20]:
2 L 14/λ14+ a 4/(2π)= m 4+½ [17]
2 L 15/λ15+ a 5/(2π)= m 5+½ [18]
λ1−150<λ14<λ1+150 [19]
λ1−150<λ15<λ1+150 [20]
where
L 14 denotes an optical distance from the fourth reflective surface to the light emission center of the first light-emitting layer,
L 15 denotes an optical distance from the fifth reflective surface to the light emission center of the first light-emitting layer,
m 4 and m 5 each denote an integer,
λ 1 , λ 14 , and λ 15 are each in unit of nm,
a 4 denotes a phase change generated upon reflection, at the fourth reflective surface, of the light of each wavelength outputted from the first light-emitting layer, and
a 5 denotes a phase change generated upon reflection, at the fifth reflective surface, of the light of each wavelength outputted from the first light-emitting layer.
14. The light-emitting device according to claim 12 , wherein
L 24 and L 25 satisfy following expressions [21] to [24]:
2 L 24/λ24+ c 4/(2π)= n 4 [21]
2 L 25/λ25+ c 5/(2π)= n 5 [22]
λ2−150<λ24<λ2+150 [23]
λ2−150<λ25<λ2+150 [24]
where
L 24 denotes an optical distance from the fourth reflective surface to the light emission center of the second light-emitting layer,
L 25 denotes an optical distance from the fifth reflective surface to the light emission center of the second light-emitting layer,
n 4 and n 5 each denote an integer,
λ 2 , λ 24 , and λ 25 are each in unit of nm,
c 4 denotes a phase change generated upon reflection, at the fourth reflective surface, of the light of each wavelength outputted from the second light-emitting layer, and
c 5 denotes a phase change generated upon reflection, at the fifth reflective surface, of the light of each wavelength outputted from the second light-emitting layer.
15. The light-emitting device according to claim 12 , further comprising a sixth reflective surface that is provided at one or more of: a location between the second reflective surface and the fourth reflective surface; a location between the fourth reflective surface and the fifth reflective surface; and a location that faces the fourth reflective surface with the fifth reflective surface being interposed therebetween.
16. The light-emitting device according to claim 1 , further comprising:
a first electrode defining the first reflective surface;
a second electrode facing the first electrode with the light-emitting layer interposed therebetween; and
a light emission surface between the first electrode and the second reflective surface, and configured to emit a light.
17. The light-emitting device according to claim 16 , wherein the first reflective surface is distanced from the light emission surface to strengthen the light of a center wavelength of a light emission spectrum of the light emission surface, and
the second reflective surface is distanced from the light-emitting layer to strengthen the light of the center wavelength of the light emission spectrum of the light emission surface.
18. The light-emitting device according to claim 16 , wherein the second electrode is between the first reflective surface and the second reflective surface.
19. The light-emitting device according to claim 16 , wherein the light emission surface is configured to emit a monochromatic light.