Organic electroluminescence element and illumination device using the same
View Patent ↗Disclosed are an organic electroluminescence element with significantly improved light extraction efficiency and improved film properties and an illumination device that uses said element. The organic electroluminescence element has a transparent electrode, an organic electroluminescence layer, and a cathode sequentially stacked on a transparent base material. The element is characterized in that the transparent base material is a transparent resin film, there is a hard coat layer on both sides, the respective refractive indices satisfy the expressions (1)-(4), and there is a function to scatter light to the light emission side with respect to the organic electroluminescence layer. Expression (1): −0.2≦n(H1)−n(A)≦0.2, Expression (2): −0.1≦n(H1)−n(B)≦0.1, Expression (3): −0.1≦n(H2)−n(B)≦0.1, Expression (4): −0.1≦n(H1)−n(H2)≦0.1. In the expressions, n(A) is the refractive index of the transparent electrode; n(H1) is the refractive index of the hard coat layer (on the transparent electrode side); n(H2) is the refractive index of the hard coat layer (on the side opposite the transparent electrode); and n(B) is the refractive index of the transparent resin film.
1. An organic electroluminescence element comprising:
a transparent substrate sequentially provided thereon, a transparent electrode, an organic electroluminescence layer and a cathode, wherein
the transparent substrate is a transparent resin film having a hard coat layer on both sides,
the transparent resin film having a refractive index in a range of not less than 1.70 and not more than 1.80,
the hard coat layer comprises a resin containing microparticles having a particle diameter of 1-400 nm in an amount of 5-30% by volume and a light scattering, polymer filler,
each refractive index of the hard coat layer satisfies Expressions (1)-(4),
the transparent substrate has a function to scatter a light to the light emission side with respect to the organic electroluminescence layer;
−0.2 ≦n ( H 1)− n ( A )≦0.2 Expression (1)
−0.1 ≦n ( H 1)− n ( B )≦0.1 Expression (2)
−0.1 ≦n ( H 2)− n ( B )≦0.1 Expression (3)
−0.1 ≦n ( H 1)− n ( H 2)≦0.1, wherein Expression (4)
n(A) is a refractive index of the transparent electrode;
n(H1) is a refractive index of the hard coat layer (on the transparent electrode side);
n(H2) is a refractive index of the hard coat layer (on an opposite side to the transparent electrode); and
n(B) is a refractive index of the transparent resin film.
2. The organic electroluminescence element of claim 1 , wherein the resin is a curable resin.
3. The organic electroluminescence element of claim 1 , wherein the transparent resin film is a film containing a light scattering filler.
4. The organic electroluminescence element of claim 1 comprising a light extraction film on an opposite side to the transparent electrode on the transparent substrate.
5. The organic electroluminescence element of claim 1 , wherein the transparent resin film is a polyester film.
6. The organic electroluminescence element of claim 1 , wherein the transparent resin film is a stretched polyethylene naphthalate film.
7. The organic electroluminescence element of claim 1 , wherein
a thickness of the hard coat layer is not less than 2 μm and not more than 50 μm, and
satisfies Expressions (5)-(7):
d ( H 1)> d ( A ) Expression (5)
d ( H 1)< d ( B ) Expression (6)
−10 μm≦ d ( H 2)− d ( H 1)≦+10 μm, wherein Expression (7)
d(A) is a thickness of the transparent electrode;
d(H1) is a thickness of the hard coat layer (on the transparent electrode side);
d(H2) is a thickness of the hard coat layer (on the opposite side to the transparent electrode); and
d(B) is a thickness of the transparent resin film.
8. An illumination device comprising the organic electroluminescence element of claim 1 .
9. The organic electroluminescence element of claim 1 , wherein the light scattering, polymer filler is made of a silicone resin, a fluorine resin or an acrylic resin.