1. Field of the Invention
The present invention relates to a white organic light emitting device and, more particularly, to a white organic light emitting device which includes first and second emissive layers each having a blue emissive layer to improve the light emission efficiency.
2. Description of the Related Art
Image display devices that are thinner, lighter and more portable and that employ organic light emitting displays (OLED), have attracted much attention. The OLED has the advantage that it can be manufactured paper-thin, with a light emitting element using a thin emissive layer between electrodes.
The OLED includes an anode transmitting light, a cathode reflecting light, and an emissive layer having a plurality of organic layers stacked between the anode and the cathode. When a voltage is applied between the cathode and the anode, light generated from the organic emissive layer is emitted through the anode, or transferred to the cathode opposite to the anode and reflected back to the anode and then emitted through the anode.
The organic emissive layer in a white organic light emitting device has a basic structure in which red (R), green (G) and blue (B) emissive layers are stacked. When the stacked R, G and B emissive layers emit light simultaneously, it is possible to obtain well-balanced white light emission. However, it is difficult to manufacture a white organic light emitting device having high efficiency and R, G and B properly balanced.
One approach to solving the problem of efficiency in the stacked structure involves the use of an intermediate, charge-injecting layer inserted between emissive layers so as to increase the quantum efficiency and light emission efficiency. However, the fabrication process is complicated.