CN101123302A - Double-sided light-emitting organic light-emitting diode and manufacturing method thereof - Google Patents

Abstract

The invention discloses a method for manufacturing a double-sided light-emitting organic light-emitting diode, which comprises the following steps: firstly, providing a transparent substrate; sequentially forming a first transparent electrode and an organic light-emitting layer on the transparent substrate; then, a second transparent electrode is formed on the organic light-emitting layer. And the step of forming the second transparent electrode includes: forming a first film layer on the organic light-emitting layer, wherein the first film layer is composed of an alkali metal compound or an alkaline earth metal compound; forming a second film layer on the first film layer, wherein the second film layer is made of a metal material and has a thickness of 20-50 angstroms; finally, a Plasma diffusion deposition process or an ion thermal evaporation process is performed to form a third film layer on the second film layer, wherein the third film layer is made of a transparent conductive material.

Description

Double-sided light-emitting organic light-emitting diode and its manufacturing method

technical field

The present invention relates to an organic light-emitting diode and a manufacturing method thereof, and particularly relates to a double-sided light-emitting organic light-emitting diode with high-transmittance electrodes and low driving voltage and a manufacturing method thereof.

Background technique

Organic light-emitting diodes are semiconductor elements that can convert electrical energy into light energy and have high conversion efficiency. Common applications are light-emitting elements for indicator lights, display panels, and optical read-write heads, etc. Due to the characteristics of organic light-emitting diodes, such as no viewing angle, simple manufacturing process, low cost, high response speed, wide temperature range and full color, etc., which meet the requirements of display characteristics in the multimedia era, it has become a research boom in recent years.

The organic light emitting diode mainly includes a glass substrate, a metal electrode, a transparent electrode and an organic light emitting layer. The basic light-emitting principle of organic light-emitting diodes is to use the metal electrode as the cathode and the transparent electrode as the anode. When a forward bias is applied between the two electrodes, electrons and holes are respectively injected into the light-emitting layer from the interface between the metal electrode and the transparent electrode. , and the two kinds of carriers meet in the light-emitting layer to generate photons through Radiative Recombination, and then achieve the phenomenon of luminescence.

1A and 1B are schematic cross-sectional views of a conventional bottom emission and top emission organic light emitting diode, respectively. First, please refer to FIG. 1A , a conventional bottom emission organic light emitting diode 100 mainly includes a transparent substrate 110 , a transparent electrode 120 , an organic light emitting layer 130 and a metal electrode 140 . The transparent electrode 120 is disposed on the transparent substrate 110 to serve as an anode of the OLED. The organic light emitting layer 130 is disposed on the transparent electrode 120 . The metal electrode 140 is disposed on the organic light emitting layer 130 to serve as a cathode of the organic light emitting diode. When a potential difference is applied between the transparent electrode 120 and the metal electrode 140 , the light 150 emitted by the organic light emitting layer 130 passes through the transparent electrode 120 and the transparent substrate 110 , and is emitted from the bottom of the organic light emitting diode 100 to the outside.

On the contrary, in the top emission organic light emitting diode 100' shown in FIG. 1B, the metal electrode 140' is formed on the transparent substrate 110, and then the organic light emitting layer 130 and the transparent electrode 120' are sequentially formed. Similarly, when a potential difference is applied between the metal electrode 140' and the transparent electrode 120', the light 150' emitted by the organic light emitting layer 130 will pass through the transparent electrode 120' and radiate from the top of the organic light emitting diode 100' to the outside world.

Although the above-mentioned bottom-emitting or top-emitting organic light-emitting diodes can still meet the application of single-sided display organic light-emitting diode displays, it is undeniable that there will be a broader market demand for organic light-emitting diode displays with double-sided display functions.

Generally speaking, at present, the top electrode (Top Electrode) of double-sided light-emitting organic light-emitting diodes is fabricated by physical vapor deposition (Physical Vapor Deposition, PVD). However, in the process of generating plasma in the physical vapor deposition method, high-energy argon ions and oxygen ions will be generated, and these high-energy argon ions and oxygen ions will hit the surface of the organic light-emitting layer, causing ion bombardment effect, and then It affects the luminous efficiency and driving voltage of the organic light emitting diode.

For the double-side light-emitting OLED, the transmittance of the transparent electrodes on the upper and lower sides and the driving voltage are actually two factors affecting its application. Therefore, how to manufacture double-sided light-emitting organic light-emitting diodes with high electrode transmittance and low driving voltage to meet the requirements of future flat-panel display applications is an important issue in the current organic light-emitting display technology.

Contents of the invention

The object of the present invention is to provide a method for manufacturing a double-sided light-emitting organic light-emitting diode, so as to solve the problem of poor transmittance of the transparent electrodes in the double-sided light-emitting organic light-emitting diode.

Another object of the present invention is to provide a double-sided light-emitting organic light-emitting diode, which has a lower device driving voltage.

To achieve the above or other objectives, the present invention provides a method for manufacturing a double-sided light-emitting organic light-emitting diode, which includes the following steps. First, a transparent substrate is provided. Afterwards, a first transparent electrode and an organic light-emitting layer are sequentially formed on the transparent substrate. Next, a second transparent electrode is formed on the organic light emitting layer. The step of forming the second transparent electrode includes: forming a first film layer on the organic light-emitting layer, the first film layer is composed of an alkali metal compound or an alkaline earth metal compound; forming a film layer on the first film layer The second film layer, the second film layer is made of a metal material, and its thickness is between 20 angstroms to 50 angstroms; finally, a plasma diffusion deposition process (Plasma diffusion deposition process) or an ion thermal The evaporation process (Ionic thermal evaporation process) is used to form a third film layer on the second film layer, and the third film layer is composed of a transparent conductive material.

In an embodiment of the invention, the transparent substrate includes a glass substrate.

In an embodiment of the present invention, the material of the first transparent electrode may be indium tin oxide, indium zinc oxide, aluminum zinc oxide, antimony tin oxide, zinc oxide, indium oxide or tin oxide.

In an embodiment of the present invention, a method for forming an organic light-emitting layer includes the following steps. Firstly, a hole injection layer is formed on the first transparent electrode; then, a hole transport layer is formed on the hole injection layer; next, a light emitting layer is formed on the hole transport layer; after that, a light emitting layer is formed on the light emitting layer electron transport layer; finally, an electron injection layer is formed on the electron transport layer.

In an embodiment of the present invention, the thickness of the first film layer is between 5 angstroms and 100 angstroms.

In one embodiment of the invention, the alkali metal compound includes a lithium compound.

In an embodiment of the present invention, the lithium compound is selected from a combination of lithium fluoride and lithium oxide.

In an embodiment of the present invention, the metal material is selected from a group consisting of aluminum, gold, silver, calcium, magnesium, magnesium-aluminum alloy, and magnesium-silver alloy.

In an embodiment of the present invention, the thickness of the third film layer is between 500 angstroms and 3000 angstroms.

In an embodiment of the present invention, the power of the plasma diffusion deposition process is between 5000W and 15000W.

In an embodiment of the invention, the operating temperature of the plasma diffusion deposition process is between 20° C. and 300° C.

In an embodiment of the present invention, the plasma gas used in the plasma diffusion deposition process includes argon, nitrogen, oxygen or water vapor.

In an embodiment of the invention, the transparent conductive material includes indium tin oxide or indium zinc oxide.

To achieve the above or other objectives, the present invention further provides a double-sided light-emitting organic light-emitting diode, which mainly includes a transparent substrate, a first transparent electrode, an organic light-emitting layer, and a second transparent electrode. The first transparent electrode is configured on the transparent substrate. The organic light emitting layer is configured on the first transparent electrode. The second transparent electrode is arranged on the organic light-emitting layer, and it includes a first film layer, a second film layer and a third film layer. The first film layer is arranged on the organic light emitting layer and is composed of an alkali metal compound or an alkaline earth metal compound. The second film layer is disposed on the first film layer and is made of a metal material, wherein the thickness of the second film layer is between 20 angstroms and 50 angstroms. The third film layer is arranged on the second film layer and is made of a transparent conductive material. The driving voltage of the double-side light emitting organic light emitting diode is less than or equal to 5 volts, and the transmittance of the second transparent electrode is greater than 50%.

In an embodiment of the invention, the transparent substrate includes a glass substrate.

In an embodiment of the present invention, the material of the first transparent electrode may be indium tin oxide, indium zinc oxide, aluminum zinc oxide, antimony tin oxide, zinc oxide, indium oxide or tin oxide.

In an embodiment of the present invention, the organic light emitting layer mainly includes a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer and an electron injection layer. The hole injection layer is configured on the first transparent electrode. The hole transport layer is configured on the hole injection layer. The light emitting layer is configured on the hole transport layer. The electron transport layer is configured on the light emitting layer. The electron injection layer is configured on the electron transport layer.

In an embodiment of the present invention, the thickness of the first film layer is between 5 angstroms and 100 angstroms.

In one embodiment of the invention, the alkali metal compound includes a lithium compound.

In an embodiment of the present invention, the lithium compound is selected from a combination of lithium fluoride and lithium oxide.

In an embodiment of the present invention, the metal material is selected from a group consisting of aluminum, gold, silver, calcium, magnesium, magnesium-aluminum alloy, and magnesium-silver alloy.

In an embodiment of the present invention, the thickness of the third film layer is between 500 angstroms and 3000 angstroms.

In an embodiment of the invention, the transparent conductive material includes indium tin oxide or indium zinc oxide.

The present invention utilizes the plasma diffusion deposition process or ion thermal evaporation process to form the third film layer (transparent conductive layer) on the second film layer (thin metal layer), because the plasma diffusion deposition process has a lower ion bombardment effect, so , so that the organic light-emitting diode manufactured according to this process can have a lower driving voltage. Furthermore, when the thickness of the second film layer is controlled between 20 angstroms and 50 angstroms, the transmittance of the transparent electrode will be greater than 50%, and the driving voltage of the element will be less than or equal to 5 volts, so, according to The double-sided light-emitting organic light-emitting diode manufactured by the above process has the characteristics of high electrode transmittance and low driving voltage.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments are exemplified below and described in detail with accompanying drawings.

Description of drawings

1A and 1B are schematic cross-sectional views of a conventional bottom emission type and top emission type organic light emitting diode, respectively.

2A to 2C are cross-sectional schematic diagrams of the manufacturing process of a double-sided light-emitting organic light-emitting diode in a preferred embodiment of the present invention.

Fig. 3 is a schematic diagram of a plasma diffusion deposition system.

Fig. 4 is the thickness of the second film layer, the driving voltage of the device and the components obtained by testing the components composed of the stacked structure of CuPc/NPB/Alq3/Alq3 and various transparent electrodes (with different second film thicknesses) according to the present invention. The relationship between the transmittance of the transparent electrode.

Detailed ways

2A to 2C are cross-sectional schematic diagrams of the manufacturing process of a double-sided light-emitting organic light-emitting diode in a preferred embodiment of the present invention. First, please refer to FIG. 2A , a transparent substrate 210 is provided. In an embodiment of the present invention, the transparent substrate 210 may be a glass substrate or a substrate made of other suitable transparent materials. Next, please refer to FIG. 2B , a first transparent electrode 220 and an organic light emitting layer 230 are sequentially formed on the transparent substrate 210 . Generally speaking, the material of the first transparent electrode 220 can be indium tin oxide, indium zinc oxide, aluminum zinc oxide, antimony tin oxide, zinc oxide, indium oxide or tin oxide. In addition, in an embodiment of the present invention, the manufacturing method of the organic light-emitting layer 230 includes the following steps: firstly, a layer of hole injection layer 231 is formed on the first transparent electrode 220; One layer of hole-transporting layer 232; Next, form a layer of light-emitting layer 233 on the hole-transporting layer 232; Then, form a layer of electron-transporting layer 234 on the light-emitting layer 233; layer electron injection layer 235 . In this way, the fabrication process of the organic light emitting layer 230 is completed. It should be noted that, in addition to the above-mentioned five film layers, the organic light-emitting layer 230 may only include any one, any two, any three or any of the above-mentioned five film layers. Four film layers. The present invention does not impose any limitation on the type and number of film layers included in the organic light-emitting layer 230 .

Next, please refer to FIG. 2C , a second transparent electrode 240 is formed on the organic light emitting layer 230 . The second transparent electrode 240 of the present invention is composed of a first film layer 241 , a second film layer 242 and a third film layer 243 . First, a first film layer 241 is formed on the organic light-emitting layer 230. The first film layer is made of a lithium compound, such as lithium fluoride, lithium oxide, etc., and its thickness is between 5 angstroms and 100 angstroms. Between Angles. In this embodiment, the first film layer 241 is composed of lithium fluoride. Next, a second film layer 242 is formed on the first film layer 241. The second film layer 242 is made of a thin metal layer, such as: aluminum, gold, silver, calcium, magnesium, magnesium aluminum alloy, magnesium silver Alloys...etc. The transmittance of the entire second transparent electrode 240 mainly depends on the thickness of the second film layer 242 , therefore, the transmittance of the entire second transparent electrode 240 can be changed by adjusting the thickness of the second film layer 242 . In an embodiment of the present invention, the preferred thickness range of the second film layer 242 is between 20 angstroms and 50 angstroms. In addition, the first film layer 241 and the second film layer 242 can be formed by sputtering, thermal evaporation or physical vapor deposition.

Finally, the present invention utilizes a plasma diffusion deposition process or an ion thermal evaporation process to form a third film layer 243 on the second film layer 242. The third film layer 243 is made of a transparent conductive material, such as: indium tin oxide, Indium Zinc Oxide... etc., and its thickness is between 500 angstroms and 3000 angstroms. So far, the fabrication of the double-sided light emitting organic light emitting diode 200 is completed.

Fig. 3 is a schematic diagram of a plasma diffusion deposition system. Please refer to FIG. 3 , the plasma diffusion deposition system 300 mainly includes a plasma gun (Plasma Gun) 310 , a target 320 and a plasma beam controller 330 . The substrate 210 to be deposited on is directly above the target 320 . In addition, in this embodiment, the target 320 is composed of ITO. The plasma 312 generated by the plasma gun 310 is turned by the control of the plasma beam controller 330 to heat the target material 320; the target material 320 will be sublimated and deposited on the substrate 210 after being heated, so that the indium tin oxide thin film is completed deposition.

In an embodiment of the present invention, the plasma gas used in the plasma diffusion deposition process includes argon, nitrogen, oxygen or water vapor. In addition, the power of the plasma diffusion deposition process is between 5000W and 15000W, and its operating temperature is between 20°C and 300°C. Since the formation of the third film layer 243 by the plasma diffusion deposition process can reduce the ion bombardment effect, the double-sided light-emitting organic light emitting diode 200 manufactured according to the above process has a lower driving voltage.

In order to prove that the double-sided light-emitting organic light-emitting diodes produced by the above process have better electrode transmittance and lower device driving voltage, the present invention uses CuPc (200 angstroms)/NPB (500 angstroms)/Alq3 (350 angstroms)/Alq3 (150 angstroms) stacked structure was tested with various transparent electrodes (with different thicknesses of the second film layer) to obtain the thickness of the second film layer (thin metal film) of the transparent electrode The relationship between the thickness, the driving voltage of the element and the transmittance of the transparent electrode. It can be seen from FIG. 4 that when the thickness of the second film layer is between 20 angstroms and 50 angstroms, the transmittance of the transparent electrode will be greater than 50%, and its driving voltage will be less than or equal to 5 volts. In this way, it can reach High electrode penetration and low driving voltage requirements.

In summary, the transparent electrode of the double-sided light-emitting organic light emitting diode of the present invention is composed of three film layers-the first film layer composed of a lithium compound (for example: lithium fluoride)/the first film layer composed of a metal material (such as : a second film layer composed of aluminum)/a third film layer composed of a transparent conductive material (for example: indium tin oxide). The feature of the present invention is that after forming the first film layer and the second film layer, a third film layer is formed on the second film layer by using a plasma diffusion deposition process or an ion thermal evaporation process, because the plasma diffusion deposition process has a lower The ion bombardment effect, therefore, can make the organic light-emitting diodes manufactured according to this process have a lower driving voltage. According to the experimental results of the present invention, it can be seen that when the thickness of the second film layer is between 20 angstroms and 50 angstroms, the transmittance of the transparent electrode will be greater than 50%, and the driving voltage of the element is about less than or equal to 5 volts, so , so that the double-sided light-emitting organic light-emitting diode has the characteristics of high electrode transmittance and low driving voltage.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, this The protection scope of the invention should be defined by the claims.

Claims (23)

1. A method for manufacturing a double-sided light-emitting organic light-emitting diode, comprising: providing a transparent substrate; sequentially forming a first transparent electrode and an organic light-emitting layer on the transparent substrate; Forming a second transparent electrode on the organic light-emitting layer, wherein the step of forming the second transparent electrode includes: forming a first film layer on the organic light-emitting layer, wherein the first film layer is composed of an alkali metal compound or an alkaline earth metal compound; forming a second film layer on the first film layer, wherein the second film layer is made of a metal material, and its thickness is between 20 angstroms and 50 angstroms; and A plasma diffusion deposition process or an ion thermal evaporation process is performed to form a third film layer on the second film layer, wherein the third film layer is made of a transparent conductive material. 2 . The method for manufacturing a double-sided light-emitting organic light emitting diode as claimed in claim 1 , wherein the transparent substrate comprises a glass substrate. 3 . 3. The method for manufacturing a double-sided light emitting organic light emitting diode as claimed in claim 1, wherein the material of the first transparent electrode is selected from indium tin oxide, indium zinc oxide, aluminum zinc oxide, antimony One of tin oxide, zinc oxide, indium oxide or a combination of tin oxide. 4. The method for manufacturing a double-sided light emitting organic light emitting diode as claimed in claim 1, wherein the step of forming the organic light emitting layer comprises: forming a hole injection layer on the first transparent electrode; forming a hole transport layer on the hole injection layer; forming a light emitting layer on the hole transport layer; forming an electron transport layer on the light emitting layer; and An electron injection layer is formed on the electron transport layer. 5 . The method for manufacturing a double-sided light emitting organic light emitting diode as claimed in claim 1 , wherein the thickness of the first film layer is between 5 angstroms and 100 angstroms. 6 . The method for manufacturing a double-sided light emitting organic light emitting diode as claimed in claim 1 , wherein the alkali metal compound comprises a lithium compound. 7 . 7 . The method for manufacturing a double-sided light emitting organic light emitting diode as claimed in claim 6 , wherein the lithium compound is selected from one of the combinations of lithium fluoride and lithium oxide. 8. The method for manufacturing double-sided light-emitting organic light-emitting diodes according to claim 1, wherein the metal material is selected from a combination of aluminum, gold, silver, calcium, magnesium, magnesium-aluminum alloy, and magnesium-silver alloy. one. 9 . The method for manufacturing a double-sided light emitting organic light emitting diode as claimed in claim 1 , wherein the thickness of the third film layer is between 500 angstroms and 3000 angstroms. 10 . The method for manufacturing double-sided light emitting organic light emitting diodes according to claim 1 , wherein the power of the plasma diffusion deposition process is between 5000W and 15000W. 11 . 11 . The method for manufacturing double-sided light emitting organic light emitting diodes according to claim 1 , wherein the operating temperature of the plasma diffusion deposition process is between 20° C. and 300° C. 12 . The method for manufacturing double-sided light-emitting organic light-emitting diodes as claimed in claim 1 , wherein the plasma gas used in the plasma diffusion deposition process includes argon, nitrogen, oxygen or water vapor. 13 . 13 . The method for manufacturing a double-sided light emitting organic light emitting diode according to claim 1 , wherein the transparent conductive material comprises indium tin oxide or indium zinc oxide. 14 . 14. A double-sided light-emitting organic light-emitting diode, comprising: a transparent substrate; a first transparent electrode configured on the transparent substrate; an organic light-emitting layer configured on the first transparent electrode; and A second transparent electrode configured on the organic light-emitting layer, wherein the second transparent electrode includes: A first film layer is disposed on the organic light-emitting layer and is composed of an alkali metal compound or an alkaline earth metal compound; A second film layer is disposed on the first film layer and is made of a metal material, wherein the thickness of the second film layer is between 20 angstroms and 50 angstroms; and a third film layer configured on the second film layer and made of a transparent conductive material; Wherein, the driving voltage of the double-sided light emitting organic light emitting diode is less than or equal to 5 volts, and the transmittance of the second transparent electrode is greater than 50%. 15. The double-sided light emitting organic light emitting diode as claimed in claim 14, wherein the transparent substrate comprises a glass substrate. 16. The double-sided light emitting organic light emitting diode according to claim 14, wherein the material of the first transparent electrode is selected from indium tin oxide, indium zinc oxide, aluminum zinc oxide, antimony tin oxide , zinc oxide, indium oxide or one of the combinations of tin oxide. 17. The double-sided light-emitting organic light-emitting diode according to claim 14, wherein the organic light-emitting layer comprises: a hole injection layer configured on the first transparent electrode; a hole transport layer configured on the hole injection layer; a light emitting layer configured on the hole transport layer; an electron transport layer disposed on the light-emitting layer; and An electron injection layer is configured on the electron transport layer. 18. The double-sided light emitting organic light emitting diode as claimed in claim 14, wherein the thickness of the first film layer is between 5 angstroms and 100 angstroms. 19. The double-sided light emitting organic light emitting diode as claimed in claim 14, wherein the alkali metal compound comprises a lithium compound. 20 . The double-sided light emitting organic light emitting diode as claimed in claim 19 , wherein the lithium compound is selected from a combination of lithium fluoride and lithium oxide. 21 . 21. The double-sided light-emitting organic light-emitting diode as claimed in claim 14, wherein the metal material is selected from the group consisting of aluminum, gold, silver, calcium, magnesium, magnesium-aluminum alloy and magnesium-silver alloy. 22. The double-sided light emitting organic light emitting diode as claimed in claim 14, wherein the thickness of the third film layer is between 500 angstroms and 3000 angstroms. 23. The double-sided light emitting organic light emitting diode as claimed in claim 14, wherein the transparent conductive material comprises indium tin oxide or indium zinc oxide.

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