Organic electroluminescence device and method of fabricating the same
View Patent ↗An organic EL device includes: a reflective electrode; a transparent electrode opposite the reflective electrode; an organic layer including a light-emitting layer between the reflective electrode and transparent electrode; and a low refractive index layer between the reflective electrode and light-emitting layer. The low refractive index layer has a function of transporting/injecting electrons/holes, and has a lower refractive index than the light-emitting layer. Distance between the surface of the reflective electrode and a central light-emitting position of the light-emitting layer is 300 nm or less. Furthermore, Δn×d/λ≦−0.009 and Δn×d/λ≦−0.02 are satisfied when the reflective electrode comprises Al and Ag, respectively, where: λ denotes the central light-emitting wavelength of light generated in the light-emitting layer; Δn denotes the refractive index difference between the low refractive index layer and the light-emitting layer, with the refractive index of the light-emitting layer as reference; and d denotes the thickness of the low refractive index layer.
1. An organic electroluminescence (EL) device comprising:
a reflective electrode;
a transparent electrode opposite the reflective electrode;
a light-emitting layer between the reflective electrode and the transparent electrode; and
a low refractive index layer between the reflective electrode and the light-emitting layer,
wherein the low refractive index layer has a function of transporting or injecting electrons or holes, and has a refractive index lower than a refractive index of the light-emitting layer,
a distance between a top surface of the reflective electrode and a central light-emitting position of the light-emitting layer is 300 nm or less,
the reflective electrode comprises Al, and
Δn×d/λ≦−0.009 is satisfied where:
λ denotes a central light-emitting wavelength of light generated in the light-emitting layer;
Δn denotes a difference between the refractive index of the low refractive index layer and the refractive index of the light-emitting layer when the refractive index of the light-emitting layer is used as reference; and
d denotes a thickness of the low refractive index layer,
wherein the light-emitting layer emits light when voltage is applied to the reflective electrode and the transparent electrode.
2. An organic electroluminescence (EL) device comprising:
a reflective electrode;
a transparent electrode opposite the reflective electrode;
a light-emitting layer between the reflective electrode and the transparent electrode; and
a low refractive index layer between the reflective electrode and the light-emitting layer,
wherein the low refractive index layer has a function of transporting or injecting electrons or holes, and has a refractive index lower than a refractive index of the light-emitting layer,
a distance between a top surface of the reflective electrode and a central light-emitting position of the light-emitting layer is 300 nm or less,
the reflective electrode comprises Ag, and
Δn×d/λ≦−0.02 is satisfied where:
λ denotes a central light-emitting wavelength of light generated in the light-emitting layer;
Δn denotes a difference between the refractive index of the low refractive index layer and the refractive index of the light-emitting layer when the refractive index of the light-emitting layer is used as reference; and
d denotes a thickness of the low refractive index layer,
wherein the light-emitting layer emits light when voltage is applied to the reflective electrode and the transparent electrode.
3. The organic EL device according to claim 1 , further comprising
an organic layer between the reflective electrode and the low refractive index layer, the organic layer having a function of transporting or injecting electrons or holes.
4. The organic EL device according to claim 1 ,
wherein the low refractive index layer is in contact with the light-emitting layer.
5. The organic EL device according to claim 1 further comprising one of the following, in an interface at which a refractive index in the organic EL device changes:
a diffraction grating;
a light-diffusing layer;
a microlens; and
a pyramid structure.
6. The organic EL device according to claim 1 ,
wherein the low refractive index layer comprises (i) a material having a function of transporting or injecting electrons or holes and (ii) nanoparticles which are mixed into the material.
7. The organic EL device according to claim 1 ,
wherein the low refractive index layer includes:
a nanoparticle layer comprising nanoparticles; and
a function layer above the nanoparticle layer, the function layer comprising a material having a function of transporting or injecting electrons or holes.
8. The organic EL device according to claim 1 ,
wherein the low refractive index layer includes:
two function layers each having a function of transporting or injecting electrons or holes; and
a nanoparticle layer between the two function layers, the nanoparticle layer comprising nanoparticles.
9. The organic EL device according to claim 6 ,
wherein the nanoparticles have a grain size less than or equal to the thickness of the low refractive index layer.
10. The organic EL device according to claim 6 ,
wherein the nanoparticles are porous particles.
11. The organic EL device according to claim 6 ,
wherein the nanoparticles have a refractive index of 1.5 or less.