Stacked organic electroluminescent device and method for manufacturing thereof

A stacked organic electroluminescent device, which includes a substrate, an anode layer, organic emitting layers, carrier generation layers, reflecting layers and a cathode layer, is provided. The substrate has first emitting region, second emitting region, and third emitting region. The anode layer is above the substrate. And above the anode layer are the following layers sequentially: a first organic emitting layer, a first carrier generation layer, a second organic emitting layer, a second carrier generation layer, and a third organic emitting layer. The first reflecting layer, the second reflecting layer, and the third reflecting layer are in the stacked structure. And each of them is disposed corresponding to the first emitting region, the second emitting region, and the third emitting region. The cathode layer is on the third organic emitting layer. The stacked organic electroluminescent device has full color spectrum, improved luminant efficiency, and color purity.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to an organic electroluminescent device and method for manufacturing thereof. In particular, it relates to a stacked organic electroluminescent device (Stacked OLED) and method for manufacturing thereof.

2. Description of Related Art

The organic electroluminescent device (OLED) is a device using the luminescent characteristic of organic functional materials for providing display purposes, its luminescent structure typically is constructed of a pair of electrodes and organic functional material layers. As the current passes through the area between the anode and the cathode, the electrons and the holes in the organic functional material layers are recombined to produce photons, thus allowing the organic functional material layers, according to its material characteristics, to produce light emitting mechanisms for the different emitting colors.

In the manufacturing process of the full color spectrum organic emitting device, the conventional technology fabricates a plurality of red (R), green (G), and blue (B) organic luminescent structures. In addition, the aforementioned R, G, B organic luminescent structures are assorted to produce an organic emitting device with full color spectrum results. But, in this kind of full color spectrum organic emitting device, the diminishing life cycles and the luminescent brightness of each color of organic functional material are different. Therefore, the organic emitting device faces issues regarding discrepancies in luminescent purity or in brightness for each color.

To solve the aforementioned issues, researchers have proposed a multilayer stacked OLED for producing single-colored light or white light organic electroluminescent device with higher luminant efficiency. It takes several single-colored light or white light organic electroluminescent devices stacked together to increase their luminant efficiency.FIG. 1illustrates a schematic diagram for a multilayer stacked OLED. Referring toFIG. 1, this multilayer stacked OLED100has a substrate110, a pair of electrodes120,130, a plurality of organic emitting layers140, and a plurality of electrically conductive layers150. The organic emitting layers140are mutually stacked. In addition, the electrically conductive layers150are located between each two organic emitting layers140. As the current passes through the area between the electrodes120,130, the electrons160, and the holes170in each organic emitting layer140, will be recombined to form a photon180. Therefore, as illustrated inFIG. 1, via the compounding effect of the photons180, the luminant efficiency for the multilayer stacked OLED100is thus improved. But the structure illustrated inFIG. 1only shows the single-colored light or white light, the demands for full color spectrum cannot be achieved.

SUMMARY OF THE INVENTION

Based on the above, the objective of the present invention is to provide a stacked organic electroluminescent device that can fulfill the full color spectrum demands, and provide improved luminant efficiency and color purity.

Another objective of the present invention is to provide a method for the manufacturing of a stacked organic electroluminescent device. It is capable of manufacturing the stacked organic electroluminescent device with full color spectrum, improved luminant efficiency, and improved color purity.

Based on the aforementioned or other objectives, the present invention proposes a stacked organic electroluminescent device, which includes a substrate, an anode layer, a plurality of organic emitting layers, a plurality of carrier generation layers (CGL), a plurality of reflecting layers, and a cathode layer. The substrate has a first emitting region, a second emitting region, and a third emitting region. The anode layer is disposed on the substrate. The first organic emitting layer is disposed on the anode layer. The second organic emitting layer is disposed on the first organic emitting layer. The third organic emitting layer is disposed on the second organic emitting layer. The first carrier generation layer is disposed between the first organic emitting layer and the second organic emitting layer. The second carrier generation layer is disposed between the second organic emitting layer and the third organic emitting layer. The first reflecting layer is disposed in the first emitting region and between the substrate and the first organic emitting layer. The second reflecting layer is disposed in the second emitting region and between the first organic emitting layer and the second organic emitting layer. The third reflecting layer is disposed in the third emitting region and between the second organic emitting layer and the third organic emitting layer. The cathode layer is disposed on the third organic emitting layer.

In an embodiment of the present invention, the aforementioned stacked organic electroluminescent device, for example, further includes a color filter array disposed on the cathode layer.

In an embodiment of the present invention, the aforementioned stacked organic electroluminescent device, for example, further includes a hole transport layer (HTL) disposed between the anode layer and the first organic emitting layer.

In an embodiment of the present invention, the aforementioned second reflecting layer is disposed in the second emitting region and between the first carrier generation layer and the second organic emitting layer.

In an embodiment of the present invention, the aforementioned second reflecting layer is disposed in the second emitting region and between the first carrier generation layer and the first organic emitting layer.

In an embodiment of the present invention, the aforementioned third reflecting layer is disposed in the third emitting region and between the second carrier generation layer and the third organic emitting layer.

In an embodiment of the present invention, the aforementioned third reflecting layer is disposed in the third emitting region and between the second carrier generation layer and the second organic emitting layer.

In an embodiment of the present invention, the material of the aforementioned first carrier generation layer and the second carrier generation layer, for example, is selected from WO3and combinations thereof.

In an embodiment of the present invention, the material of the aforementioned first reflecting layer, the second reflecting layer, and the third reflecting layer, for example, is selected from the group including aluminum, chromium, silver, magnesium alloy and combinations thereof.

In an embodiment of the present invention, the material of the aforementioned anode layer, for example, includes a transparent or non-transparent conductive material.

In an embodiment of the present invention, the material of the aforementioned cathode layer, for example, includes a transparent conductive material.

The present invention proposes a method for manufacturing of a stacked organic electroluminescent device having the following procedures. First, provides a substrate with a first emitting region, a second emitting region, and a third emitting region. Later, forms a first reflecting layer above the first emitting region. Furthermore, forms an anode layer, which covers the first reflecting layer, above the substrate. Afterwards, forms a first organic emitting layer above the anode layer. Later, forms a first carrier generation layer above the first organic emitting layer. Furthermore, forms a second organic emitting layer above the first carrier generation layer. Afterwards, forms a second carrier generation layer above the second organic emitting layer. Later, forms a third organic emitting layer above the second carrier generation layer. Afterwards, forms a cathode layer above the third organic emitting layer. Wherein, between the first organic emitting layer and the second organic emitting layer, and above the second emitting region, further includes the forming of the second reflecting layer. And disposed between the second organic emitting layer and the third organic emitting layer, and in the third emitting region, further includes the forming of the third reflecting layer.

In an embodiment of the present invention, the process for forming the aforementioned first organic emitting layer, the second organic emitting layer, and the third organic emitting layer is using the same patterned mask.

In an embodiment of the present invention, the aforementioned method for manufacturing of the stacked organic electroluminescent device, for example, further includes the forming of a color filter array above the cathode layer.

In an embodiment of the present invention, the aforementioned method for manufacturing of stacked organic electroluminescent device, for example, further includes the forming of a hole transport layer between the anode layer and the first organic emitting layer.

In an embodiment of the present invention, the material of the aforementioned first carrier generation layer and the second carrier generation layer, for example, is selected from the group including WO3and combinations thereof.

In an embodiment of the present invention, the material of the aforementioned first reflecting layer, the second reflecting layer, and the third reflecting layer is selected from the group including aluminum, chromium, silver, magnesium alloy and combinations thereof.

In an embodiment of the present invention, the material of the aforementioned anode layer, for example, includes a transparent or non-transparent conductive material.

In an embodiment of the present invention, the material of the aforementioned cathode layer, for example, includes a transparent conductive material.

The present invention is adopting overall stacking of the organic emitting layer to provide full color spectrum capability and to achieve colored light with improved color purity. In addition, the present invention uses the same patterned mask with the vapor deposition process for forming the stacked organic emitting layer structures. Therefore, the amount of the patterned mask can be reduced, and thus reducing production cost. In addition, the layered setup of the reflecting layers can increase the luminant efficiency of the stacked organic electroluminescent device, and thus increasing its brightness.

To better understand the aforementioned advantages, characteristics, and functionalities, further details of the present invention, and further features and benefits thereof, are described below. The accompanying drawings, which are incorporated herein, illustrate the present invention and, together with the embodiments, further serve to explain the principles of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

First Embodiment

FIG. 2is a structural schematic diagram illustrating a stacked organic electroluminescent device for an embodiment of the present invention. Referring toFIG. 2, this stacked organic electroluminescent device200includes a substrate210, an anode layer220, a plurality of organic emitting layers232,234,236, a plurality of carrier generation layers242,244, a plurality of reflecting layers252,254,256and a cathode layer260, wherein the substrate210has a first emitting region212, a second emitting region214, and a third emitting region216. The anode layer220is disposed above the substrate210. The organic emitting layer232is disposed above the anode layer220. The organic emitting layer234is disposed above the organic emitting layer232. The organic emitting layer236is disposed above the organic emitting layer234. The carrier generation layer242is disposed between the organic emitting layer232and the organic emitting layer234. The carrier generation layer244is disposed between the organic emitting layer234and the organic emitting layer236. The reflecting layer252is disposed in the first emitting region212and is disposed between the substrate210and the organic emitting layer232. The reflecting layer254is disposed in the second emitting region214and is disposed between the organic emitting layer232and the organic emitting layer234. The reflecting layer256is disposed in the third emitting region216and is disposed between the organic emitting layer234and the organic emitting layer236. And the cathode layer260is disposed above the organic emitting layer236.

Continuing to refer toFIG. 2, the substrate210can be a plastic substrate or a glass substrate. And the material of the anode layer220, which is disposed above the substrate210, for example, is a transparent or non-transparent conductive material. And the material of the cathode layer260, for example, is a transparent conductive material for allowing each colored light292,294,296for passing through. The aforementioned transparent conductive material, for example, can be selected from indium-tin oxide, indium-zinc oxide, aluminum-zinc oxide, cadmium-tin oxide, and others. And the aforementioned non-transparent material, for example, can be selected from a metal or an alloy.

Between the anode layer220and the cathode layer260, the stacked structures of a plurality of organic emitting layers232,234,236, carrier generation layers242,244, and reflecting layers252,254,256are disposed, wherein the organic emitting layer232, for example, emits red light. The organic emitting layer234, for example, emits green light. And the organic emitting layer236, for example, emits blue light.

Particularly, the stacked organic electroluminescent device200of the present invention has a special characteristic that is the using of overall stacking of each organic emitting layer232,234,236. And, the allocation of the carrier generation layer242,244between each organic emitting layer232,234,236allows the charge carrier to transmit smoothly. In an embodiment, the material of the carrier generation layer242and of the carrier generation layer244, for example, is selected from WO3.

Furthermore, due to the organic electroluminescent device of the present invention adopting a overall stacked structure design, therefore, the same patterned mask (not illustrated) can be used to perform the full surface vapor deposition for disposing the organic emitting layers232,234,236sequentially. Unlike the conventional full color spectrum organic electroluminescent device, which requires different patterned mask (at least three) to perform the vapor deposition, and further defining each independent organic luminescent structure in each emitting region. Therefore, the stacked organic electroluminescent device200of the present invention can save costs of patterned masks, thus production cost is reduced.

Another special feature of the present invention is that the reflecting layer252,254,256are disposed in the stacked structure of the stacked organic electroluminescent device200and in the corresponding first emitting region212, the second emitting region214, and the third emitting region216appropriately. As a result, the emitting rays from each organic emitting layer232,234,236directing towards the substrate210(not illustrated), can be reflected by the reflecting layers252,254,256. So, the reflecting rays can be combined with the emitting rays from each organic emitting layer232,234,236heading towards the direction of the cathode layer260(in the visual direction). And producing each colored light292,294,296having improved luminant efficiency. Therefore, using the setup of the reflecting layer252,254,256can increase the luminant efficiency of the stacked organic electroluminescent device200.

Particularly, the position of the reflecting layer252,254,256are disposed in different layers, and the locations can be adjusted appropriately. Referring toFIG. 2, using the reflecting layers254,256as examples in an embodiment, the reflecting layer254, for example, is disposed in the second emitting region214and is disposed between the carrier generation layer242and the organic emitting layer234. In another embodiment, the reflecting layer254can also be disposed in the second emitting region214and between the carrier generation layer242and the organic emitting layer232(not illustrated).

Continuing referring toFIG. 2, the reflecting layer256, for example, is disposed in the third emitting region216and between the carrier generation layer244and the organic emitting layer236. In another embodiment, the reflecting layer256can also be disposed in the third emitting region216and is disposed between the carrier generation layer244and the organic emitting layer234(not illustrated). Furthermore, the material of the reflecting layer252,254,256, for example, is selected from the group including aluminum, chromium, silver, magnesium, alloy, and combinations thereof.

Continuing referring toFIG. 2, in an embodiment of the present invention, the stacked organic electroluminescent device200, for example, further includes a hole transport layer270. And it is disposed between the anode layer220and the organic emitting layer232. The material of this hole transport layer270, for example, is selected from or polymer materials such as polyethylene dioxythiophene (PEDOT) and polystyrene sulfonate (PSS), and can also be other known hole transport materials. Its function is to assist the transportation of electron hole.

Furthermore, the stacked organic electroluminescent device200illustrated inFIG. 2, for example, further includes a color filter array280, disposed above the cathode layer260. The color filter array280has a red filter282, a green filter284and a blue filter286for filtering each colored light292,294,296to output red light, green light, and blue light having improved color purity.

FIG. 3Ais a schematic diagram illustrating the emission spectrum for colored light without having passing through the red filter.FIG. 3Bis a schematic diagram illustrating the emission spectrum for the colored light after passing through the red filter. Referring toFIG. 2, anyone can know that the colored light292emitted from the first emitting region212, includes the red light emitted from the organic emitting layer232, the green light emitted from the organic emitting layer234, and the blue light emitted from the organic emitting layer236. Therefore, referring to the spectrum inFIG. 3A, the colored light292includes the red, green and blue light components. As the colored light292passing through the red filter282, the red light component of the colored light292is filtered out. So, a red light292R having improved color purity, as illustrated inFIG. 3B, is provided.

FIG. 4Ais a schematic diagram illustrating the emission spectrum for the colored light without having passing through the green filter.FIG. 4Bis a schematic diagram illustrating the emission spectrum for the colored light after passing through the green filter. Referring toFIG. 2, anyone can know that the colored light294emitted from the second emitting region214, includes the green light emitted from the organic emitting layer234, and the blue light emitted from the organic emitting layer236. Therefore, referring toFIG. 4A, the colored light294includes the green and blue light components. As the colored light294is filtered by the green filter284, the green light component is filtered out from the colored light294. And the green light294G with improved color purity, as illustrated inFIG. 4B, is provided.

FIG. 5is a schematic diagram illustrating the emission spectrum for the colored light after passing through the blue filter. Referring toFIG. 2, anyone can know that the colored light296emitted from the third emitting region216only includes the blue light component. Therefore, as can be seen from the spectrum inFIG. 5, after the colored light296passing through the blue filter284, the obtained blue light296B, and the colored light296are almost same.

In summary, the stacked organic electroluminescent device200of the present invention uses overall stacking of the organic emitting layers232,234,236, for arriving at the results of full color spectrum and obtaining colored light with improved color purity. Only one patterned mask is needed to produce the stacking of all the organic emitting layers232,234,236, thus the production cost can be reduced. Furthermore, the reflecting layers252,254,256disposed in different layers can increase the luminant efficiency and brightness of the stacked organic electroluminescent device200.

Second Embodiment

FIG. 6AtoFIG. 6Eare procedural flow schematic diagrams illustrating the method for manufacturing of a stacked organic electroluminescent device, according to an embodiment of the present invention. Please refers to the procedures illustrated inFIG. 6Ato FIG.6E., and this is a continuous process.

First, as illustrated inFIG. 6A, a substrate210is provided. It has the first emitting region212, the second emitting region214, and the third emitting region216. The substrate210, for example, is a plastic or glass substrate.

Later, as illustrated inFIG. 6B, the reflecting layer252is formed above the first emitting region212. The reflecting layer252is disposed in the first emitting region212and above the substrate210. The method for forming the reflecting layer252, for example, uses a patterned mask310to perform. The reflecting layer252is formed in the first emitting region212on the substrate210. In an embodiment of the present invention, the material of reflecting layer252, for example, is selected from the group including aluminum, chromium, silver, magnesium, alloy and combinations thereof.

Then, as illustrated inFIG. 6C, the anode layer220is formed above the substrate210; and the anode layer220covers the reflecting layer252. The method for forming the anode layer220, for example, uses sputtering process to comprehensively form the anode layer220above the substrate210. In an embodiment, the material of the anode layer220, for example, includes transparent or non-transparent conductive material, wherein the non-transparent conductive material, for example, is a metal, alloy or others. And the transparent conductive material, for example, includes indium-tin oxide, indium-zinc oxide, aluminum-zinc oxide, cadmium-tin oxide and others.

Later, as illustrated inFIG. 6D, the organic emitting layer232is formed above the anode layer220. The method for forming the organic emitting layer232, for example, uses a patterned mask312to perform the vapor deposition process330. So, the organic material can be comprehensively formed on the anode layer220. In an embodiment, a hole transport layer270can be formed between the anode layer220and the organic emitting layer232for improving the hole transportation between the anode layer220and the organic emitting layer232.

Afterwards, as illustrated inFIG. 6E, the carrier generation layer242is formed above the organic emitting layer232. The organic emitting layer234is formed above the carrier generation layer242. The carrier generation layer244is formed above the organic emitting layer234. The organic emitting layer236is formed above the carrier generation layer244. And the cathode layer260is formed above the organic emitting layer236, wherein the reflecting layer254is formed between the organic emitting layer232and the organic emitting layer234, and in the position of the second emitting region214. And the reflecting layer256is formed between the organic emitting layer234and the organic emitting layer236, and in the position of third emitting region216. The materials of the carrier generation layers242,244, the reflecting layers252,254,256, and the cathode layer260are already described in the first embodiment, so no further descriptions are repeated. The method of forming the carrier generation layer242,244is similar to the organic emitting layer232described inFIG. 6D. In other word, the carrier generation layer242,244can be manufactured using a patterned mask (not illustrated) with the vapor deposition process. Besides, the forming method of the reflecting layer254,256is similar to the described manufacturing method inFIG. 6Bof the reflecting layer252, but different patterned mask (not illustrated) are used to perform the sputtering process320.

Particularly, in an embodiment of the present invention, the aforementioned forming process for the organic emitting layer232, the organic emitting layer234, and the organic emitting layer236uses the same patterned mask312. Therefore, the stacked organic electroluminescent device200of the present invention can save the cost of patterned masks. Unlike the conventional full color spectrum organic electroluminescent device, it requires different patterned masks (at least three) to perform the vapor deposition method for defining various organic luminant structures in different emitting regions.

Referring toFIG. 6E, a color filter array280is further formed above the cathode layer280. The color filter array280has the red filter282, the green filter284, and the blue filter286. The color filter array280is used to provide colored lights having improved color purity. And the method for forming the color filter array280, for example, is printing method or ink jet.

Based on the aforementioned, the stacked organic electroluminescent device has the following advantages in the present invention:(1) the stacked organic electroluminescent device of the present invention uses overall stacking of the organic emitting layer, and can achieve full color spectrum results and can obtain colored light with improved color purity; and it uses the same patterned mask to perform the vapor deposition process for forming the stacked organic emitting layer structure. Therefore, the amount of patterned mask can be reduced, thus production cost is reduced too.(2) The reflecting layers are disposed in different layers appropriately. So, the luminant efficiency and brightness of the stacked organic electroluminescent device of the present invention can be increased.

Although an embodiment has been mentioned above to explain this invention, it does not limit to this invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of it. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.