Light-emitting device having optical resonance layer
Provided is a light-emitting device which has a simple structure and can be manufactured in a simple process, has increased light coupling efficiency and brightness, and can reduce adverse effects of optical resonance on a view angle and emission spectrum. The light-emitting device includes a substrate; a light-emitting diode formed on the substrate; and an optical resonance layer formed outside the light-emitting diode that induces resonance of light emitted from the light-emitting diode.
1. A light-emitting device comprising:
a substrate;
a light-emitting diode arranged on the substrate;
an interlayer arranged between the substrate and the light-emitting diode; and
an optical resonance layer consisting of a first layer and a second layer arranged between the light-emitting diode and the substrate,
wherein an uppermost surface of the first layer directly contacts the interlayer, a lowermost surface of the second layer directly contacts the substrate, and a lowermost surface of the first layer directly contacts an uppermost surface of the second layer, the optical resonance layer to induce resonance of light emitted from the light-emitting diode, and
wherein a refractive index of the second layer is higher than that of the first layer.
2. The light-emitting device of claim 1 , wherein the second layer has a higher refractive index than the first layer by 0.2 or more.
3. The light-emitting device of claim 1 , wherein the first layer has a refractive index in the range of 1 to 1.6.
4. The light-emitting device of claim 1 , wherein the first layer comprises nano porous silica, siloxane, magnesium fluoride, calcium fluoride, Teflon, silica aero gel, or silicon oxide.
5. The light-emitting device of claim 1 , wherein the second layer has a refractive index in the range of 1.6 to 2.3.
6. The light-emitting device of claim 1 , wherein the second layer comprises silicon nitride, titanium oxide, hafnium dioxide, niobium oxide, tantalum oxide, antimony oxide, synthetic polymer, or benzocylobutene (BCB).
7. The light-emitting device of claim 1 , wherein the interlayer is composed of a denser material than the first layer.
8. The light-emitting device of claim 1 , wherein the interlayer has a refractive index in the range of 1.3 to 2.3.
9. The light-emitting device of claim 1 , wherein the interlayer comprises Ormocer, silicon oxide, benzocylobutene (BCB), or silicon nitride.
10. The light-emitting device of claim 1 , wherein:
the light-emitting diode comprises a pair of electrodes opposing each other and a light-emitting layer arranged between the electrodes,
one electrode of the pair of electrodes comprises a reflective layer that reflects light emitted from the light-emitting layer, and
the optical resonance layer opposes the reflective layer with the light-emitting layer arranged therebetween.
11. The light-emitting device of claim 10 , satisfying equation 4:
t 4=( n λ)/ 2 (4)
wherein
t 4 is a distance from a reflection interface of the reflective layer to an interface between the first layer and the second layer;
n is a positive integer; and
λ is a wavelength of light emitted from the light-emitting layer.
12. The light-emitting device of claim 11 , wherein t 4 is controlled by adjusting a thickness of at least one of the first layer and the interlayer.
13. The light-emitting device of claim 10 , satisfying equation 5:
t 5=(2 n + 1)λ/ 4 (5)
wherein
t 5 is a distance from a reflection interface of the reflective layer to an outer surface of the second layer;
n is a positive integer; and
λ, is a wavelength of light emitted from the light-emitting layer.
14. The light-emitting device of claim 13 , wherein t 5 is controlled by adjusting a thickness of the second layer.
15. The light-emitting device of claim 1 , wherein the light-emitting diode is an organic light-emitting diode.