Light emitting device for improving the color purity of emitted light and electronic apparatus
A light emitting device includes: a light emitting element which includes a first electrode layer, a second electrode layer, and a light emitting function layer disposed between the first electrode and the second electrode; a reflection layer which reflects light emitted from the light emitting function layer toward the light emitting function layer; and a translucent transflective layer which is disposed opposite the reflection layer with the light emitting function layer interposed therebetween to reflect some of the light emitted from the light emitting function layer toward the light emitting function layer and to transmit the remainder of the light. The translucent transflective layer is centered between a first layer having a refractive index n 1 and being disposed on a side of the reflection layer and a second layer having a refractive index n 2 (where n 2 <n 1 ) and being disposed opposite the first layer.
1. A light emitting device comprising:
a light emitting element which includes a first electrode layer, a second electrode layer, and a light emitting function layer disposed between the first electrode and the second electrode;
a reflection layer which reflects light emitted from the light emitting function layer toward the light emitting function layer; and
a translucent transflective layer which is disposed opposite the reflection layer with the light emitting function layer interposed therebetween to reflect some of the light emitted from the light emitting function layer toward the light emitting function layer and to transmit the remainder of the light,
wherein the translucent transflective layer is disposed between a first layer having a refractive index n 1 and being disposed on a side of the reflection layer and a second layer having a refractive index n 2 (where n 2 <n 1 ) and being disposed opposite the first layer, the second layer directly contacts the translucent transflective layer.
2. The light emitting device according to claim 1 , wherein the first layer includes the whole or a part of the light emitting function layer.
3. The light emitting device according to claim 2 ,
wherein the translucent transflective layer includes the second electrode layer and serves as cathode, and
wherein the first layer includes at least one of an electron transport layer and an electron injection layer as a part of the light emitting function layer.
4. The light emitting device according to claim 1 , wherein an optical distance from the reflection layer to an interface opposite the reflection layer in the translucent transflective layer is determined on the basis of d calculated by Expression (1):
2 d+φ D +φ U =mλ (1),
where λ is a wavelength set as a resonance target, φ D is a phase change when light having a wavelength λ and traveling from the light emitting function layer to the reflection layer is reflected from the reflection layer, and φ U is a phase change when light having a wavelength λ and traveling from the light emitting function layer to the translucent transflective layer is reflected from the translucent transflective layer, and m is a positive integer.
5. The light emitting device according to claim 1 , wherein the thickness of the translucent transflective layer is in the range of 5 to 20 [nm].
6. The light emitting device according to claim 1 , wherein the second layer is made of a material having a light transmitting property.
7. The light emitting device according to claim 1 ,
wherein a plurality of the light emitting elements are provided and the plurality of light emitting elements each correspond to a peculiar light emission color, and
wherein the thickness of the second layer is set so that a half width of a spectrum of light transmitting through the translucent transflective layer and having the light emission color is narrowed.
8. The light emitting device according to claim 7 , further comprising a passivation layer which is disposed opposite the reflection layer with the translucent transflective layer interposed therebetween and prevents one of water and oxygen from entering the light emitting element,
wherein the thickness of the passivation layer is set so that the half width is narrowed.
9. An electronic apparatus comprising the light emitting device according to claim 1 .
10. A light emitting device comprising:
a light emitting element which includes a first electrode layer, a second electrode layer, and a light emitting function layer disposed between the first electrode and the second electrode;
a reflection layer which reflects light emitted from the light emitting function layer toward the light emitting function layer; and
a translucent transflective layer which is disposed opposite the reflection layer with the light emitting function layer interposed therebetween to reflect some of the light emitted from the light emitting function layer toward the light emitting function layer and to transmit the remainder of the light, wherein the translucent transflective layer is centered between a high refractive index layer having a refractive index n 3 and being disposed on a side of the reflection layer and an inert gas having a refractive index n 4 (where n 4 <n 3 ) and being disposed opposite the high refractive index layer, the inert gas directly contacts the translucent transflective layer.