Organic electroluminescent devices having improved light extraction
View Patent ↗Organic electroluminescent devices having improved light extraction include a light-scattering medium disposed adjacent thereto. The light-scattering medium has a light scattering anisotropy parameter g in the range from greater than zero to about 0.99, and a scatterance parameter S less than about 0.22 or greater than about 3.
1. A light source comprising:
a light-emitting device; and
a light-scattering medium optically coupled to the light-emitting device,
wherein the light scattering medium has a light scattering anisotropy g in a range from about 0 to about 0.99, and a scatterance S is selected from the group consisting of 0<S≦0.22 and S≧3; and
the scatterance and light emitted by the light source possess azimuthal symmetry.
2. A light source comprising:
a light-emitting device; and
a light-scattering medium optically coupled to the light-emitting device, wherein the light scattering medium has a light scattering anisotropy g in a range from about 0.8 to about 0.95, and a scatterance S greater than about 3; and
the scatterance and light emitted by the light source possess azimuthal symmetry.
3. The light source of claim 2 , wherein the light-emitting device is an organic electroluminescent device.
4. The light source of claim 1 , wherein the light-emitting device is an organic electroluminescent device.
5. The light source of claim 3 , wherein the light-emitting device comprises an organic electroluminescent material disposed between two electrodes.
6. The light source of claim 3 , wherein the light-scattering medium comprises light-scattering particles dispersed in a matrix.
7. The light source of claim 6 , wherein the light scattering particles have a median particle size d 50 of about 6 micrometers.
8. The light source of claim 6 , wherein the light-scattering medium is a layer having a thickness from about 400 micrometers to about 600 micrometers.