1. Field of the Invention
The present invention relates to an organic light-emitting element and a light-emitting device including the same.
2. Discussion of Related Art
An organic light-emitting element is a self-light-emitting element using electroluminescence, in which light is emitted when an electric current flows in an organic light-emitting compound. The organic light-emitting element has advantages of an excellent thermostability and a low driving voltage, and, thus, it has drawn attention as a next-generation element in various fields of industry, such as the display industry and the lighting industry.
However, the organic light-emitting element is an element requiring a low voltage and a high electric current, and as an area of the element is increased, a sheet resistance of a transparent electrode included in the element is increased. An electrode layer in a layered structure of the organic light-emitting element has a limited electrical conductivity. In particular, reduction in sheet resistance of a transparent electrode layer is limited. If each organic light-emitting element is large-scaled, a sheet resistance of a transparent electrode is increased and a partial voltage drop may occur. Currently, a luminous efficiency of an organic light-emitting element is about 30 lm/W in a white element having a two-stack structure, and under this circumstance, in order to obtain a luminous flux of about 600 lm which corresponds to a luminous flux of a single incandescent light bulb, an organic light-emitting element having an area of about 30×30 cm2 is required.
Typically, in order to manufacture an element having an area of about 10×10 cm2 and uniformly emitting light, a transparent electrode having a sheet resistance of about 1 Ω/□ is required. However, it is almost impossible for an ITO electrode to have a sheet resistance of about 1 Ω/□. Therefore, an additional auxiliary electrode is needed. If aluminum metal having an aperture ratio of 90% is used as an auxiliary electrode, an aluminum sheet having a thickness of about 280 nm is needed to obtain a sheet resistance of 1 Ω/□.
However, a sheet resistance of a transparent electrode decreases in inverse proportion to an area of a light-emitting element. Therefore, in order for an organic light-emitting element having an area of about 30×30 cm2 to emit light with a uniform luminance, a transparent electrode of about 1 Ω/□ is required. In order to obtain a sheet resistance of about 1 Ω/□, aluminum used as an auxiliary electrode needs to be formed to have a thickness of 2.8 μm. It is inefficient to deposit metal to such a thickness, and such a thickness makes it difficult to perform a photolithography process.
Therefore, in order to replace an incandescent light bulb or a fluorescent lamp having a luminous flux greater than the incandescent light bulb with an organic light-emitting element having a current luminous efficiency, it is efficient to arrange multiple organic light-emitting elements, each having an area of 10×10 cm2, rather than manufacture an organic light-emitting element having an area of 30×30 cm2 or more.