Organic electroluminescence device having transparent control layer with low ambient reflection and enhanced contrast
View Patent ↗An organic electroluminescence device with a low reflectivity includes organic electroluminescence layers, a transparent electrode, a thin metal electrode, a control layer, and an auxiliary electrode. The transparent electrode and the thin metal electrode are sited on both sides of the OEL layer, respectively, in order to excite it to emit light. The auxiliary electrode and the thin metal electrode are mostly separated by a control layer. Both the auxiliary electrode and the thin metal electrode are locally connected to maintain electrically connected. Therefore, the control layer is not necessarily conductive and its material selection is not restricted by the requirement of work function matching with adjacent layers. The disclosed OLED device with a low reflectivity does not require a circular polarizer. It can be used for both active-matrix and passive-matrix OLED displays. The reflection of ambient light can be largely reduced to increase the contrast of the display panel.
1. An organic electroluminescence device having transparent control layer with low ambient reflection and enhanced contrast, comprising:
a plurality of organic electroluminescence layers;
a transparent electrode and a thin metal electrode, sited on both sides of the organic electroluminescence layers, respectively, to excite the organic electroluminescence layer to emit light, wherein the thin metal electrode is semi-transparent;
a control layer with a thickness less than 300 nm, which is adjacent to the thin metal electrode, for reducing the reflection of an ambient light from the thin metal electrode; and
a metallic material auxiliary electrode, which is adjacent to the control layer;
wherein most region of the control layer is sandwiched between the auxiliary electrode and the thin metal electrode, the auxiliary electrode and the thin metal electrode are electrically connected through a conductive region.
2. The organic electroluminescence device of claim 1 , wherein the organic electroluminescence layers contain a combination of a hole injection layer, a hole transport layer, an emission layer, an electron transport layer, an electron injection layer, and a carrier generation layer.
3. The organic electroluminescence device of claim 1 , wherein the transparent electrode is made of a material selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), and thin metal layers.
4. The organic electroluminescence device of claim 1 , wherein the thin metal electrode is made of a material selected from the group consisting of metals, alloys, and metal oxides.
5. The organic electroluminescence device of claim 1 , wherein a thickness of the thin metal electrode is below 20 nm.
6. The organic electroluminescence device of claim 1 , wherein the control layer is made of a transparent material having an average absorption coefficient between 400 nm and 700 nm less than 10 4 cm −1 .
7. The organic electroluminescence device of claim 1 , wherein the control layer is made of a material selected from the group consisting of inorganic insulating materials, inorganic semiconductor materials, organic insulating materials, organic semiconductor materials, and their combinations.
8. The organic electroluminescence device of claim 1 , wherein the auxiliary electrode is made of a material selected from the group consisting of metals and alloys.
9. The organic electroluminescence device of claim 1 , wherein a thickness of the auxiliary electrode is above 30 nm.
10. The organic electroluminescence device of claim 1 further comprising a transparent substrate whose upper surface is formed in sequence the transparent electrode, the organic electroluminescence layers, the thin metal electrode, the control layer, and the auxiliary electrode.
11. The organic electroluminescence device of claim 10 , wherein a lower surface of the transparent substrate is coated with an anti-reflection coating (ARC).
12. The organic electroluminescence device of claim 10 , wherein a lower surface of the transparent substrate is attached with another transparent substrate coated with an ARC.
13. The organic electroluminescence device of claim 1 further comprising a substrate whose one surface is formed in sequence the auxiliary electrode, the control layer, the thin metal electrode, the organic electroluminescence layer, and the transparent electrode.
14. The organic electroluminescence device of claim 1 further comprising a black matrix formed in a region corresponding to the conductive region.