1. Field of the Invention
The present invention relates to a full color organic light emitting display device (OLED) and a method of fabricating the same, and more particularly, to a full color dual emission OLED having a color conversion layer or a color filter layer with a moisture absorbent on an encapsulating substrate and a method of fabricating the same.
2. Discussion of the Background
Generally, an OLED includes a substrate, an anode arranged on the substrate, an emission layer (EML) arranged on the anode, a cathode arranged on the EML, and an encapsulating substrate. In such an OLED, applying a voltage between the anode and the cathode injects holes and electrons into the EML. The holes and electrons then recombine in the EML to generate excitons, which emit light when transitioning from an excited state to a ground state.
In order to realize a full color OLED, emission layers corresponding to respective red (R), green (G), and blue (B) light may be formed. However, the emission layers that emit R, G, and B light, respectively, have different lifetime characteristics. Hence, it may be difficult to maintain white balance over long periods of time, and there is a limitation in patterning each pixel so that a high-resolution display device may not be advantageously realized.
To cope with this problem, a method that includes forming an emission layer that emits a single color of light has been proposed. The method further includes forming a color filter layer for extracting light corresponding to a predetermined color from the light emitted from the emission layer, or forming a color conversion layer for converting the light emitted from the emission layer into light of a predetermined color. As an example thereof, U.S. Pat. No. 6,515,418 discloses an active matrix OLED including an emission layer that emits white light and a color filter layer formed by photolithography. Furthermore, U.S. Pat. No. 6,522,066 discloses an active matrix OLED including an emission layer that emits blue light and a color filter layer formed by photolithography.
An encapsulating substrate for protecting an anode, an emission layer, and a cathode is attached to the substrate. The emission layer is apt to be affected by moisture and oxygen, so that a moisture absorbent may be disadvantageously attached thereto after forming a separate region for mounting the moisture absorbent within the encapsulating substrate.
USPTO Backgrounds
USPTO Backgrounds