Organic electroluminescence device
View Patent ↗An organic electroluminescence device having two electrodes and a plurality of organic layers between the two electrodes, in which the organic layers include a light emitting layer that emits light when an electric field is applied between the two electrodes. The device further includes a plurality of metal fine particles, which generates a local plasmon by light emitted from the light emitting layer, inside of at least either one of the electrodes or adjacent to a side of the electrode facing the organic layers and inside of a conductive organic layer, and at least some of the plurality of metal fine particles are disposed adjacent to the light emitting layer. Here, as the metal fine particles, particles having a scattering cross section σ S which is larger than an absorption cross section σ A thereof with respect to light emitted from the light emitting layer are used.
1. An organic electroluminescence device, comprising two electrodes and a plurality of organic layers between the two electrodes, the organic layers including a light emitting layer that emits light when an electric field is applied between the two electrodes, wherein: the device further comprises a plurality of metal fine particles, which generates a local plasmon by emission light emitted from the light emitting layer, inside of at least either one of the two electrodes or adjacent to a side of the at least either one of the two electrodes facing the organic layers and inside of a conductive organic layer;
wherein a maximum length d of the metal fine particles satisfies Formula (1) below:
d
>
3
λ
3
Im
[
n
⋒
2
-
1
n
⋒
2
+
1
]
4
π
3
n
3
Abs
[
n
⋒
2
-
1
n
⋒
2
+
1
]
2
3
n
⋒
=
n
particle
/
n
where, λ is an emission wavelength, n is a refractive index of the conductive layer, and n particle is a complex refractive index of the metal fine particles; wherein the maximum length d has an upper value of 120 nm;
at least some of the plurality of metal fine particles are located adjacent to the light emitting layer; and a scattering cross section σ S of the metal fine particles with respect to emission light emitted from the light emitting layer is larger than an absorption cross section σ A of the metal fine particles with respect to the emission light.
2. The organic electroluminescence device of claim 1 , wherein a maximum length d of the metal fine particles is greater than a mean free path of electrons in a metal constituting the metal fine particles.
3. The organic electroluminescence device of claim 1 , wherein the light emitting layer is formed of an organic phosphor material.
4. The organic electroluminescence device of claim 1 , wherein the either one of the electrodes is formed of a transparent conductive material.
5. The organic electroluminescence device of claim 1 , wherein the either one of the electrodes is formed of a conductive material which is less likely to generate a surface plasmon by the emission light than a metal constituting the metal fine particles.
6. The organic electroluminescence device of claim 1 , wherein the metal fine particles account for not less than 5% of an area of the either one of the electrodes.
7. The organic electroluminescence device of claim 1 , wherein the either one of the electrodes is formed on a substrate.