Organic light-emitting device
First Claim
1. An organic light-emitting device comprising:
- a substrate, which is light-transmitting;
a transparent ITO electrode, which is above an upper surface of the substrate as an anode;
a composite film layer with a gradually varying refraction index, which is sandwiched between the substrate and the transparent ITO electrode, and whose refraction indices at the two interfaces are substantially the same as those of the ITO electrode and the substrate, respectively, as it varies along the direction perpendicular to the substrate;
an organic light-emitting layer, which is formed on the ITO electrode; and
a metal conduction electrode, which is formed on the organic light-emitting layer.
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Abstract
The present invention relates to an organic light-emitting device which provides an electroluminescence (EL) or photoluminescence (PL) device with high external quantum efficiency. The present invention forms a composite film layer with continuously changing refraction indices between an ITO transparent electrode and a substrate made of plastic or glass. The refraction index of the composite film layer is the same as the ITO electrode at the interface with the ITO electrode. It decreases along the direction perpendicular to the substrate in a linear or nonlinear way. The refraction index is the same as that of the plastic or glass at the interface with the substrate. This way can avoid reflection due to the difference in the refraction index across the interface. The excited light originally trapped in the ITO electrode can be guided outwards. A preferred mean is to incorporate a photon wave guide formed at the interface between the substrate and the air to increase the external quantum efficiency of this type of organic light-emitting devices.
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Citations
20 Claims
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1. An organic light-emitting device comprising:
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a substrate, which is light-transmitting;
a transparent ITO electrode, which is above an upper surface of the substrate as an anode;
a composite film layer with a gradually varying refraction index, which is sandwiched between the substrate and the transparent ITO electrode, and whose refraction indices at the two interfaces are substantially the same as those of the ITO electrode and the substrate, respectively, as it varies along the direction perpendicular to the substrate;
an organic light-emitting layer, which is formed on the ITO electrode; and
a metal conduction electrode, which is formed on the organic light-emitting layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An organic light-emitting device, comprising:
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a light-transmitting substrate having a predetermined refraction index;
a light-transmitting anode electrode having a refraction index that is different from the refraction index of the substrate, the anode electrode being spaced apart from the substrate;
a composite film layer sandwiched between the substrate and the anode electrode so as to have an interface with the substrate and an interface with the anode electrode, the composite film layer having a refraction index that varies, in a direction perpendicular to the substrate, from a first value adjacent the interface with the substrate to a second value adjacent the interface with the anode electrode, the first value being substantially the same as the refraction index of the substrate and the second value being substantially the same as the refraction index of the anode electrode;
an organic light-emitting layer on the anode electrode; and
a cathode electrode on the light-emitting layer, wherein the composite film layer is a multi layer structure composed of a plurality of films made of at least two materials with different refraction indices, and the refraction index of the composite film layer varies as a function of the thickness of each film and the composition ratio of the at least two materials therein. - View Dependent Claims (17, 18, 19, 20)
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Specification