Organic light-emitting device and method of fabricating the same
Provided is an organic light-emitting device including: a substrate; an anode on the substrate; an organic layer on the anode and including an emission layer; a cathode on the organic layer; an optical auxiliary layer on the cathode; and a capping layer on the optical auxiliary layer, wherein, in a visible light region, the optical auxiliary layer has a lower refractive index and a higher absorption coefficient as the capping layer.
1. An organic light-emitting device comprising:
a substrate;
an anode on the substrate;
an organic layer on the anode and comprising an emission layer;
a cathode on the organic layer;
an optical auxiliary layer on the cathode; and
a capping layer on the optical auxiliary layer,
wherein, in a visible light region, the optical auxiliary layer has a lower refractive index and a higher absorption coefficient than of the capping layer.
2. The organic light-emitting device as claimed in claim 1 , wherein, in a visible light region, the optical auxiliary layer has a refractive index in a range of about 1.1 to about 2.0 and an absorption coefficient in a range of about 1 to about 3.
3. The organic light-emitting device as claimed in claim 1 , wherein the refractive index of the optical auxiliary layer is in a range of about 1.1 to about 1.5 in a wavelength region between about 400 nm to about 550 nm, and is in a range of about 1.5 to about 2 in a wavelength region between about 550 nm to about 700 nm.
4. The organic light-emitting device as claimed in claim 1 , wherein a difference between the refractive index of the optical auxiliary layer and the refractive index of the capping layer is in a range of about 0.5 to about 2.0 in a wavelength region between about 400 nm and about 550 nm.
5. The organic light-emitting device as claimed in claim 4 , wherein a difference between the refractive index of the optical auxiliary layer and the refractive index of the capping layer in a wavelength region between about 550 nm and about 700 nm is smaller than a difference between the refractive index of the optical auxiliary layer and the refractive index of the capping layer in the wavelength region between about 400 nm and about 550 nm.
6. The organic light-emitting device as claimed in claim 1 , wherein the optical auxiliary layer has a higher absorption coefficient in a wavelength region between about 550 nm and about 700 nm than the optical auxiliary layer in a wavelength region between about 400 nm and about 550 nm.
7. The organic light-emitting device as claimed in claim 1 , wherein the optical auxiliary layer includes ytterbium (Yb).
8. The organic light-emitting device as claimed in claim 1 , wherein the organic layer further comprises:
a hole transport region between the anode and the emission layer; and
an electron transport region between the cathode and the emission layer.
9. The organic light-emitting device as claimed in claim 8 , wherein the electron transport region includes an electron injection layer of a same material as the optical auxiliary layer.
10. The organic light-emitting device as claimed in claim 1 , wherein the capping layer comprises a triarylamine derivative, a carbazole derivative, a benzimidazole derivative, a triazol derivative, ITO, IZO, SiO 2 , SiN x , Y 2 O 3 , WO 3 , MoO 3 , Al 2 O 3 , or a combination thereof.
11. The organic light-emitting device as claimed in claim 1 , wherein the cathode includes a first metal of silver (Ag) and a second metal of at least one of aluminum (Al), platinum (Pt), ytterbium (Yb), neodymium (Nd), and magnesium (Mg), and a content of the first metal is greater than that of the second metal.
12. The organic light-emitting device as claimed in claim 1 , wherein the anode is a reflective electrode.
13. The organic light-emitting device as claimed in claim 1 , wherein the capping layer includes a plurality of layers having different refractive indices from each other.
14. The organic light-emitting device as claimed in claim 1 , wherein the cathode further includes at least one intermediate layer, the intermediate layer being made of the same material as a material for forming the optical auxiliary layer.
15. The organic light-emitting device as claimed in claim 14 , wherein the optical auxiliary layer and the intermediate layer include Yb.
16. A method of fabricating an organic light-emitting device, the method comprising:
providing a substrate;
forming an anode on the substrate;
forming an organic layer including an emission layer, on the anode;
forming a cathode on the organic layer;
forming an optical auxiliary layer on the cathode; and
forming a capping layer on the optical auxiliary layer,
wherein, in a visible light region, the optical auxiliary layer has a lower refractive index and a higher absorption coefficient than that of the capping layer.
17. The method as claimed in claim 16 , wherein forming the optical auxiliary layer continuously occurs after forming the cathode, in a chamber that is the same as a chamber used for forming the cathode.
18. The method as claimed in claim 17 , wherein:
the electron transport region includes an electron injection layer, and
he electron injection layer, the cathode, and the optical auxiliary layer are sequentially formed in the same chamber.
19. The method as claimed in claim 18 , wherein the electron injection layer and the optical auxiliary layer are formed of the same materials.
20. The method as claimed in claim 19 , wherein the optical auxiliary layer includes Yb.