Highly efficient organic light emitting device using substrate having nanosized hemispherical recesses and method for preparing the same
The present invention provides an organic light emitting device comprising a substrate, a first electrode, an organic material layer and a second electrode in sequentially laminated form, wherein a plurality of continued hemispherical recesses are formed on an upper surface of the substrate aligned adjacent to the first electrode. In addition, The present invention provides a method comprising the steps of a) dipping a substrate having at least one aluminum surface in an acid solution, and applying oxidation voltage of 10 to 400 V to the substrate so as to form an aluminum oxide layer on the aluminum surface of the substrate in such a manner that a plurality of continued recesses are formed on the aluminum oxide layer, and a plurality of continued recesses having curvature in identical direction to that of the recesses on the aluminum oxide layer are formed on an interface between the aluminum oxide layer and the substrate; b) removing the aluminum oxide layer from the substrate, thereby forming a plurality of continued hemispherical recesses; and c) forming an organic material layer and an electrode on one surface of the substrate formed with the hemispherical recesses.
1. An organic light emitting device comprising a substrate, a first electrode, an organic material layer, and a second electrode in sequentially laminated form; wherein, on an upper surface of the substrate aligned adjacent to the first electrode, a plurality of continued hemispherical recesses that are opaque and reflect light are formed.
2. The organic light emitting device as claimed in claim 1 , wherein each of the hemispherical recesses has a diameter of 25 to 1000 nm.
3. The organic light emitting device as claimed in claim 1 , wherein the upper surface of the substrate aligned adjacent to the first electrode is formed with aluminum.
4. The organic light emitting device as claimed in claim 1 , wherein the substrate is made from aluminum.
5. The organic light emitting device as claimed in claim 1 , wherein the substrate includes a glass layer and an aluminum layer laminated on the glass layer.
6. The organic light emitting device as claimed in claim 1 , wherein the substrate has a function identical to that of the first electrode so that the first electrode is replaced with the substrate.
7. The organic light emitting device as claimed in claim 1 , wherein the substrate is fabricated through a method comprising the steps of:
a) dipping a substrate having at least one aluminum surface in an acid solution, and applying oxidation voltage of 10 to 400 V to the substrate so as to form an aluminum oxide layer on the aluminum surface of the substrate, in such a manner that a plurality of continued recesses are formed on the aluminum oxide layer, and a plurality of continued recesses having curvature in identical direction to that of the recesses on the aluminum oxide layer are formed on an interface between the aluminum oxide layer and the substrate; and
b) removing the aluminum oxide layer from the substrate, thereby forming a plurality of continued hemispherical recesses on one surface of the substrate.
8. The organic light emitting device as claimed in claim 1 , wherein the continued hemispherical recesses face the organic material layer, and the first electrode is disposed between the continued hemispherical recesses and the organic material layer.
9. The organic light emitting device as claimed in claim 1 , further comprising a transparent thin film laminated between the substrate and the first electrode.
10. The organic light emitting device as claimed in claim 9 , wherein the transparent thin film, which is aligned adjacent to the first electrode, is formed at an upper surface thereof with corresponding hemispherical recesses in match with a plurality of continued hemispherical recesses formed on the substrate.
11. The organic light emitting device as claimed in claim 9 , wherein an upper surface of the transparent thin film, which is aligned adjacent to the first electrode, has a planar structure.
12. The organic light emitting device as claimed in claim 1 , wherein the organic material layer includes a single layer or at least two layers.
13. The organic light emitting device as claimed in claim 12 , wherein the organic material layer includes a hole injection layer, a hole transport layer, a light emitting layer and an electron transport layer.
14. A method for fabricating an organic light emitting device, comprising the steps of:
a) dipping a substrate having at least one aluminum surface in an acid solution, and applying oxidation voltage of 10 to 400 V to the substrate so as to form an aluminum oxide layer on the aluminum surface of the substrate in such a manner that a plurality of continued recesses are formed on the aluminum oxide layer, and a plurality of continued recesses having curvature in identical direction to that of the recesses on the aluminum oxide layer are formed on an interface between the aluminum oxide layer and the substrate;
b) removing the aluminum oxide layer from the substrate, thereby forming a plurality of continued hemispherical recesses on the surface of the substrate; and
c) forming an organic material layer and an electrode on one surface of the substrate formed with the hemispherical recesses.
15. The method as claimed in claim 14 , wherein, in step b), the aluminum oxide layer is removed from the substrate through one selected from the group consisting of a chemical etching process, an electrochemical etching process and an electric shock process.
16. The method as claimed in claim 14 , wherein, in step c), the organic material layer and the electrode are formed on the substrate through a physical vapor deposition process.
17. The method as claimed in claim 14 , wherein, in step c), the organic material layer is formed on the substrate through a solution process.