Electroluminescence element and lighting apparatus
View Patent ↗An electroluminescent element wherein an electrode 1 , an electroluminescent layer 2 , a high-refractive-index layer 3 (a transparent electrode layer 3 A and an intermediate layer 3 B) and a translucent body 4 are sequentially laminated. On light-emitting-surface side of the high-refractive-index layer 3 and the translucent body 4 , layers 5 A and 5 B individually having a light-scattering function are provided respectively. The presence of the light-scattering layers 5 A and 5 B on the light-emitting-surface side of the high-refractive-index layer 3 and the translucent body 4 enables to emit light from the electroluminescent element through multiple scattering of guided light, which travels inside the translucent body 4 in the planar direction while being totally reflected by the interface between the translucent body 4 and air, and other guided light, which travels inside a thin film including the electroluminescent layer 2 and the high-refractive-index layer 3.
1. An electroluminescent element, wherein an electrode, an electroluminescent layer, a high-refractive-index layer and a translucent body are sequentially laminated; and
a layer having a light-scattering function is provided on the light-emitting-surface side of each of the high-refractive-index layer and the translucent body,
wherein each of the layers having the light-scattering function contains transparent particles;
the refractive index of the transparent particles contained in the layer having the light-scattering function provided on the light-emitting-surface side of the high-refractive-index layer is 1.6 or more while the refractive index of the transparent particles contained in the layer having the light-scattering function provided on the light-emitting-surface side of the translucent body is 1.7 or less.
2. The electroluminescent element according to claim 1 , wherein a layer having a refractive index lower than that of the translucent body is present between the high-refractive-index layer and the translucent body.
3. The electroluminescent element according to claim 2 , wherein the refractive index of the layer having a refractive index lower than that of the translucent body is 1.3 or less.
4. The electroluminescent element according to claim 1 , wherein the refractive index of the layer having the light-scattering function provided on the light-emitting-surface side of the translucent body is higher than that of the translucent body.
5. The electroluminescent element according to claim 1 , wherein the high-refractive-index layer has a transparent electrode layer and an intermediate layer, a difference in a refractive index between the transparent electrode layer and the intermediate layer being less than 0.3.
6. The electroluminescent element according to claim 5 , wherein a gas barrier layer is present between the transparent electrode layer and the intermediate layer.
7. The electroluminescent element according to claim 1 , which is used as a light source of a lighting apparatus.
8. A lighting apparatus comprising a light source that uses the electroluminescent element according to claim 1 .
9. The electroluminescent element according to claim 1 , wherein the refractive index of the transparent particles contained in the layer having the light-scattering function provided on the light-emitting-surface side of the high-refractive-index layer is 1.8 or more while the refractive index of the transparent particles contained in the layer having the light-scattering function provided on the light-emitting-surface side of the translucent body is 1.57 or less.
10. The electroluminescent element according to claim 5 , wherein the intermediate layer is provided on the light-emitting surface side of the transparent electrode layer.
11. The electroluminescent element according to claim 10 , wherein the intermediate layer has insulation properties.
12. The electroluminescent element according to claim 1 , wherein the transparent particles are selected from the group consisting of zirconia particles, silica particles and titania particles.
13. The electroluminescent element according to claim 12 , wherein the electrode is a transparent ITO layer.
14. The electroluminescent element according to claim 1 , wherein the high-refractive-index layer has a refractive index of 1.7 or higher.
15. The electroluminescent element according to claim 1 , wherein the high-refractive-index layer has a refractive index of 1.9 or higher.
16. The electroluminescent element according to claim 1 , wherein the high-refractive-index layer has a refractive index of 2.0 or higher.
17. The electroluminescent element according to claim 1 , wherein the high-refractive-index layer is free of particles.