Organic electroluminescence element
View Patent ↗The electroluminescence element comprises the light-reflective-electrode separated from the luminous point by distance “d” satisfying the following formula. nd = a × λ 4 { 2 m + ϕ π } wherein ϕ = tan - 1 { 2 ( n 1 k 2 - n 2 k 1 ) n 1 2 - n 2 2 + k 1 2 - k 2 2 } λ is a wavelength of the light from the light emission layer. N is a refractive index of a certain layer between the luminous point and the light-reflective-electrode at λ. n1 and k1 is a refractive index and the extinction coefficient of the certain layer at λ. n2 and k2 is a refractive index and the extinction coefficient of the light-reflective-electrode at λ. m is 0 or 1. When “m” is 0, “a” satisfies the following formula. −1.17× n org /n EML +1.94≦ a ≦−0.16× n org /n EML +2.33 When “m” is 1, “a” satisfies the following formula. 0.28× n org /n EML +0.75≦ a ≦2.85× n org /n EML −1.23 norg is a refractive index of a predetermined layer in contact with the light emission layer to be located on the same side as the light-reflective-electrode at λ. nEML is a refractive index of the light emission layer at λ.
1. An organic electroluminescence element comprising:
an organic light emission layer which comprises a light emission layer including a luminescent material,
said organic light emission layer being provided with a first surface and a second surface which is opposite of said first surface,
a light reflective electrode being disposed on said first surface,
a light transmissive electrode being disposed on the second surface,
a light scattering layer being disposed on the light transmissive electrode,
a light transmissive substrate being disposed on said light scattering layer,
a light reflective electrode being spaced from a luminous point of said light emission layer by a distance d,
wherein
the distance “d” is defined by following formula,
nd
=
a
×
λ
4
{
2
m
+
ϕ
π
}
(
1
)
wherein
ϕ
=
tan
-
1
{
2
(
n
1
k
2
-
n
2
k
1
)
n
1
2
-
n
2
2
+
k
1
2
-
k
2
2
}
wherein
λ is defined by a wavelength of a predetermined light which is emitted from the light emission layer,
n is a refractive index of a layer which is located between the luminous point and the light reflective electrode at the light having the wavelength λ,
n 1 is a refractive index of a layer which is located between the luminous point of the light emission layer and the light reflective electrode and which is in contact with the light reflective electrode, at the light having the wavelength λ,
k 1 is an extinction coefficient of the layer which is located between the luminous point of the light emission layer and the light reflective electrode and which is in contact with the light reflective electrode, at the light having the wavelength λ,
n 2 is a refractive index of the light reflective electrode at the wavelength λ of the light,
k 2 is an extinction coefficient of the light reflective electrode at the light having the wavelength λ,
wherein
m is equal to 0 or 1,
when m is equal to 0, “a” satisfies a following formula
−1.17 ×n org /n EML +1.94 ≦a≦− 0.16 ×n org /n EML +2.33
wherein
when m is equal to 1, “a” satisfies a following formula
0.28 ×n org /n EML +0.75 ≦a≦ 2.85 ×n org /n EML −1.23
wherein
n org is a refractive index of a layer which is in contact with the light emission layer and which is located on a same side of the light emission layer as the light reflective electrode at the light having the wavelength λ,
n EML is a refractive index of the light emission layer at the light having the wavelength λ.
2. The organic electroluminescence element as set forth in claim 1 , wherein the wavelength λ is a wavelength of the light which satisfies a condition where a product obtained by multiplying a spectral radiant flux of a photoluminescence spectrum of the predetermined light and a CIE standard luminosity factor has maximum.
3. The organic electroluminescence element as set forth in claim 1 , wherein the wavelength λ is a wavelength of the light which satisfies a condition where a quotient obtained by dividing a spectral radiant flux of a photoluminescence spectrum of the predetermined light by a photon energy of each the wavelengths has maximum.
4. The organic electroluminescence element as set forth in claim 1 , wherein
said organic light emission layer comprises two light emission layers,
the distance d between said first electrode and each one of said luminous point is defined by said “d”.
5. The organic electroluminescence element as set forth in claim 2 , wherein said organic light emission layer comprises two light emission layers,
the distance d between said first electrode and each one of said luminous point is defined by said “d”.
6. The organic electroluminescence element as set forth in claim 3 , wherein said organic light emission layer comprises two light emission layers,
the distance d between said first electrode and each one of said luminous point is defined by said “d”.