Organic light-emitting display apparatus and method of manufacturing the same
An organic light-emitting display apparatus and a manufacturing method thereof have improved process stability and reliability by reducing damage to the organic light-emitting display apparatus during a manufacturing process. The organic light-emitting display apparatus includes: a substrate, a plurality of pixel electrodes, a pixel defining film, a plurality of hole control layers respectively arranged on the pixel electrodes, a plurality of emission layers respectively arranged on the hole control layers, a plurality of buffer layers respectively arranged on the emission layers, each of the buffer layers having a highest occupied molecular orbital (HOMO) energy level greater than the HOMO energy level of each of the plurality of emission layers, and an opposite electrode integrally provided over the buffer layers.
1. A method of manufacturing a display apparatus, the method comprising:
(a) forming a first pixel electrode configured to emit a first color of light, a second pixel electrode configured to emit a second color of light, and a third pixel electrode configured to emit a third color of light, wherein the first pixel electrode, the second pixel electrode, and the third pixel electrode are patterned on a substrate and apart from one another;
(b) forming a first lift-off layer comprising a fluoropolymer on the first to third pixel electrodes;
(c) forming a first photoresist on the first lift-off layer;
(d) sequentially forming a first opening and a second opening in the first photoresist and the first lift-off layer to expose the first pixel electrode, wherein the first photoresist and the first lift-off layer are formed at positions corresponding to the first pixel electrode;
(e) sequentially forming a first hole control layer, a first emission layer, and a first buffer layer, on the first pixel electrode, through the first opening and the second opening;
(f) removing the first lift-off layer and the first photoresist;
sequentially repeating operations (b) to (f) with respect to the second pixel electrode; and
sequentially repeating operations (b) to (f) with respect to the third pixel electrode,
wherein end portions of the first hole control layer, the first emission layer, and the first buffer layer are aligned with one another and form a surface parallel to a thickness direction of the first pixel electrode.
2. The method of claim 1 , wherein the sequentially repeating of operations (b) to (f) with respect to the second pixel electrode comprises:
(b) forming a second lift-off layer on the second to third pixel electrodes, the second lift-off layer comprising a fluoropolymer;
(c) forming a second photoresist on the second lift-off layer;
(d) sequentially forming a first opening and a second opening in the second photoresist and the second lift-off layer to expose the second pixel electrode, wherein the second photoresist and the second lift-off layer are formed at positions corresponding to the second pixel electrode;
(e) sequentially forming a second hole control layer, a second emission layer, and a second buffer layer, on the second pixel electrode, through the first opening and the second opening; and
(f) removing the second lift-off layer and the second photoresist,
wherein the second buffer layer protects the second emission layer in the removing of the second lift-off layer and the second photoresist.
3. The method of claim 2 , wherein the sequentially repeating of operations (b) to (f) with respect to the third pixel electrode comprises:
(b) forming a third lift-off layer on the third pixel electrodes, the third lift-off layer comprising a fluoropolymer;
(c) forming a third photoresist on the third lift-off layer;
(d) sequentially forming a first opening and a second opening in the third photoresist and the third lift-off layer to expose the third pixel electrode, wherein the third photoresist and the third lift-off layer are formed at positions corresponding to the third pixel electrode;
(e) sequentially forming a third hole control layer, a third emission layer, and a third buffer layer, on the third pixel electrode, through the first opening and the second opening; and
(f) removing the third lift-off layer and the third photoresist,
wherein the third buffer layer protects the third emission layer in the removing of the third lift-off layer and the third photoresist.
4. The method of claim 3 , further comprising forming an opposite electrode that is integrally provided over the first buffer layer, the second buffer layer, and the third buffer layer,
wherein a lowest unoccupied molecular orbital (LUMO) energy level of the first buffer layer has a value between a work function of the opposite electrode and the LUMO energy level of the first emission layer.
5. The method of claim 3 , further comprising:
forming an electronic control layer that is integrally provided over the first buffer layer, the second buffer layer, and the third buffer layer; and
forming an opposite electrode that is integrally provided on the electronic control layer,
wherein a lowest unoccupied molecular orbital (LUMO) energy level of each of the first to third buffer layers has a value between the LUMO energy level of the electronic control layer and the LUMO energy level of each of the first to third emission layers.
6. The method of claim 1 , wherein a highest occupied molecular orbital (HOMO) energy level of the first buffer layer is greater than the HOMO energy level of the first emission layer.
7. The method of claim 1 , wherein the first buffer layer comprises at least one selected from a low molecular weight organic material, an electron transport material, and a metal oxide material.
8. The method of claim 1 , wherein end portions of the first hole control layer, the first emission layer, and the first buffer layer, which are above the first pixel electrode, are aligned with one another.