CN1518132A - Organic light emitting diode for reducing external light reflection and its manufacturing process - Google Patents

Abstract

An organic light emitting diode for reducing external light reflection and its manufacturing process. In order to provide a display component and its manufacturing process with simple structure, low cost, reduced external light reflection interference and good light emitting efficiency, the present invention is proposed. The organic light emitting diode for reducing external light reflection comprises a substrate, a metal reflection layer formed on the substrate, a transparent anode electrode formed on the metal reflection layer, an organic layer formed on the transparent anode electrode, a semi-transparent electron injection cathode layer formed on the organic layer, a buffer layer formed on the semi-transparent electron injection cathode layer and a transparent electrode formed on the buffer layer; the manufacturing process comprises providing a substrate, forming a metal reflection layer on the substrate, forming a transparent anode electrode on the metal reflection layer, forming an organic layer on the transparent anode electrode, forming a semi-transparent electron injection cathode layer on the organic layer and forming a transparent electrode.

Description

Organic Light Emitting Diode and Its Manufacturing Process for Reducing External Light Reflection

technical field

The invention belongs to a display component and its manufacturing process, in particular to an organic light-emitting diode that reduces external light reflection and its manufacturing process.

Background technique

Organic Electro luminescence Display (OLED; Organic EL Display) is also known as Organic Light Emitting Diode (OLED) display due to its high brightness, fast screen response, thin and short, full-color , no viewing angle difference, no need for LCD backlight and save light source and power consumption, therefore, it can take the lead in replacing twisted nematic (Twist Nematic; TN) and super twisted nematic (Super Twist Nematic; STN) liquid crystal display market , and further replace the small-size thin film transistor liquid crystal display, and become a new generation of portable information products, mobile phones, personal digital assistants and portable computers commonly used display devices.

As shown in FIG. 1 , the basic structure of an OLED is that on a transparent substrate 10 coated with a transparent anode 12 , an organic material is sequentially coated to form an organic layer 14 , and a metal is coated to form a metal cathode 16 .

The organic layer 14 includes a hole-injecting layer (hole-Injecting layer; HIL), a hole-transporting layer (hole-transporting layer; HTL), a light-emitting layer (emitting layer; EML) and an electron-transporting layer (electron-transporting layer; ETL). ).

Usually the cathode metal is opaque and reflective. When an external voltage is applied to make the element emit light, the light is emitted through the path of the transparent anode 12 and the transparent substrate 10 .

This way of emitting light through the direction of the substrate is called bottom emission; on the contrary, the transparent conductive anode is plated on the opaque reflective substrate (or a reflective metal layer can be plated on the transparent substrate), and then After the same organic layer is coated, a transparent cathode is coated. At this time, the component emits light through the transparent cathode, which is called top emission.

Both of the above two structures are easy to reflect the incident light of the external environment due to the metal reflective layer, so that the contrast of the display panel is reduced. Therefore, traditionally, a black conductive material, such as zinc oxide, is used in the bottom emission structure to be inserted between the organic layer and the reflective cathode, so that the incident light from the external environment is absorbed by the material and avoids reflection. This structure is called black cathode (black cathode).

As shown in Fig. 2, another kind is called the interference layer (black layer) structure, and it does not absorb the incident light, but by coating multi-layers between the organic layer 22 and the metal negative plate (i.e. reflective cathode) 28 The interference layer 26 is composed of thin films with different refractive indices. By adjusting the thickness of the interference layer 26, the reflected light of the translucent electron injection cathode layer 24 and the reflective cathode 28 produces a 180° phase difference, causing destructive interference to reduce reflection The effect of light, thereby enhancing the contrast.

Whether it is black cathode (black cathode) or interference layer (black layer), the conductivity of the material is a factor to be considered. If the selected material has poor conductivity, it may lead to an increase in the driving voltage of the device, which is not in line with the low power consumption required today. The interference layer is more concerned with the refractive index of each layer of film. In this way, there is a certain difficulty in the selection of materials. In addition, as long as there is one more layer of structure in the manufacturing process, it will increase the cost and time that people do not like. Considering the time-to-market schedule, as long as one layer of structure can be reduced in the process, not only can the cost be reduced, but also the process time can be shortened, and there is no need to adjust the relevant process parameters due to the increase in the structure, which will make the product more competitive force.

Contents of the invention

The purpose of the present invention is to provide an organic light-emitting diode with simple structure, low cost, low external light reflection interference, good luminous efficiency and low external light reflection and its manufacturing process.

The organic light emitting diode for reducing external light reflection of the present invention comprises a substrate, a metal reflective layer formed on the substrate, a transparent anode electrode formed on the metal reflective layer, an organic layer formed on the transparent anode electrode, and an organic layer formed on the organic layer. The semi-transparent electron injection cathode layer, the buffer layer formed on the semi-transparent electron injection cathode layer and the transparent electrode formed on the buffer layer; the process includes providing a substrate, forming a metal reflective layer on the substrate, forming a transparent anode electrode on the metal reflective layer, An organic layer is formed on the transparent anode electrode, a translucent electron injection cathode layer is formed on the organic layer, and a transparent electrode is formed.

in:

An organic light-emitting diode process for reducing external light reflection, which includes providing a substrate, forming a metal anode electrode on the substrate, forming an organic layer on the metal anode electrode, forming a translucent electron injection cathode layer on the organic layer, and forming a transparent electrode .

An organic light-emitting diode that reduces the reflection of external light, which includes a substrate, a metal anode electrode formed on the substrate, an organic layer formed on the transparent anode electrode, a translucent electron injection cathode layer formed on the organic layer, and a cathode layer formed on the organic layer. Semi-transparent electrons are injected into the buffer layer on the cathode layer and the transparent electrode formed on the buffer layer.

The semi-transparent electron injection cathode layer is formed with organic materials to form a buffer layer for protecting the transparent electrode during sputtering; the transparent electrode is formed on the buffer layer.

The thickness of the translucent electron injection cathode layer is about 0.5-5nm.

The organic light-emitting diode that reduces the reflection of external light in the present invention includes a substrate, a metal reflective layer formed on the substrate, a transparent anode electrode formed on the metal reflective layer, an organic layer formed on the transparent anode electrode, and an organic layer formed on the organic layer. The translucent electron injection cathode layer, the buffer layer formed on the semitransparent electron injection cathode layer and the transparent electrode formed on the buffer layer; the process includes providing a substrate, forming a metal reflective layer on the substrate, and forming a transparent anode electrode on the metal reflective layer 1. Forming an organic layer on the transparent anode electrode, forming a translucent electron injection cathode layer on the organic layer and forming a transparent electrode. When the external light passes through the translucent electron injection cathode layer, part of the incident light is reflected by the translucent electron injection cathode layer to generate the first reflected light; as for the other part of the incident light, it will pass through the translucent electron injection cathode layer until the metal reflection layer to generate reflection and form the second reflected light; in use, by adjusting the thickness of the organic layer and the thickness of the transparent anode electrode, the first reflected light reflected by the semi-transparent electron injection cathode layer and the second reflected light reflected by the metal reflective layer The two reflected lights produce a 180° phase difference, thereby causing destructive interference, thereby reducing the reflection of external light, reducing the interference of external incident light, and improving the contrast of the device; that is, the present invention adjusts the thickness of the organic layer and the transparent anode electrode , which can reduce the interference of external incident light, improve the contrast of the display, and achieve good luminous efficiency. Not only the structure is simple and the cost is low, but also the external light reflection interference is reduced and the luminous efficiency is good, so as to achieve the purpose of the present invention.

Description of drawings

FIG. 1 is a schematic diagram of the structure of a known bottom-emission light-emitting diode.

FIG. 2 is a schematic diagram of the structure of a known bottom-emission light-emitting diode (interference layer structure).

FIG. 3 is a schematic diagram of Step 2 of Embodiment 1 of the organic light-emitting diode process for reducing the reflection of external light according to the present invention.

FIG. 4 is a structural schematic diagram of Embodiment 1 of an organic light-emitting diode that reduces the reflection of external light according to the present invention.

FIG. 5 is a schematic diagram of Step 2 of Embodiment 2 of the organic light-emitting diode process for reducing the reflection of external light according to the present invention.

FIG. 6 is a schematic structural diagram of Embodiment 2 of an organic light-emitting diode that reduces the reflection of external light according to the present invention.

Detailed ways

Embodiment one

As shown in FIG. 4 , the organic light-emitting diode that reduces the reflection of external light in the present invention includes a substrate 30, a metal reflective layer 32 formed on the substrate 30, a transparent anode electrode 34 formed on the metal reflective layer 32, and a transparent anode electrode 34 formed on the transparent anode. The organic layer 36 on the electrode 34 , the translucent injection cathode layer 38 formed on the organic layer 36 , the buffer layer 40 formed on the semitransparent injection cathode layer 38 , and the transparent electrode 42 formed on the buffer layer 40 .

The thickness of the translucent injected cathode layer 38 is about 0.5-5 nm.

The organic light-emitting diode (OLED) process for reducing external light reflection of the present invention comprises the following steps:

step one

As shown in Figure 3, a substrate 30 is provided

The material of the substrate 30 can be selected from appropriate materials that are light-transmitting or opaque, so as to carry organic light-emitting diode elements;

step two

As shown in Figure 3, a metal reflective layer 32 is formed

Metal materials such as aluminum and chromium are formed on the substrate 30 by evaporation or sputtering to form a film to form a metal reflective layer 32 to reflect the light emitted by the organic light emitting diode itself;

step three

As shown in Figure 4, a transparent anode electrode 34 is formed

Indium tin oxide (Indium Tin Oxide; ITO), indium zinc oxide (Indium ZincOxide; IZO) and other transparent conductive electrode materials, and sputtering, electron beam evaporation (Electron Beam Evaporation), thermal evaporation ( Thermal Evaporation), chemical vapor deposition (Chemical Vapor Deposition) or spray pyrolysis (Spray Pyrolysis) and other methods to form a transparent anode electrode 34 on the metal reflective layer 32, which is used as the anode electrode of the organic light-emitting body;

step four

Form the organic layer 36

Fluorescent or phosphorescent pigments or complex materials selected from Alq, NPB, CuPc, C545T, DCJTB, CBP, Balq, Ir(ppy) _3, etc., and vacuum evaporation method, electron beam heating vacuum evaporation method, ion Chemical evaporation method, organic molecular wire evaporation method, plasma polymerization method, vacuum evaporation polymerization method, immersion coating method, spin coating method, Langmuir-Blodgett (LB) thin film method, Sol-Gel method or electrolytic polymerization method, etc. forming an organic layer 36 on the transparent anode electrode 34;

step five

Forming a translucent electron injection cathode layer 38

Select a material with better conductivity and more stability, such as lithium fluoride (LiF) metal compound as the material of the electron injection cathode layer 38, to form a translucent electron injection cathode layer 38 on the organic layer 36 by sputtering or vapor deposition, and then The combination of vapor-deposited aluminum metal can effectively reduce the driving voltage value, and the thickness must be thin enough to have a certain degree of light transmission to form a translucent state. The atomic layer thickness is about 0.5-5nm. In addition, magnesium silver (Mg-Ag), aluminum lithium (Al-Li) alloy electrode materials also have the same effect;

step six

Form buffer layer 40

On the translucent electron injection cathode layer 38, a buffer layer 40 is formed from organic materials such as CuPc; in order to produce a protective effect when sputtering the next layer of transparent electrodes, because high-energy sputtering may damage the organic layer. , then it is necessary to add this buffer layer 40 to absorb most of the energy;

step seven

Form the transparent electrode 42

Select transparent conductive materials such as indium tin oxide and indium zinc oxide, and form a transparent electrode 42 on the buffer layer 40 by sputtering, electron beam evaporation, etc.; the sputtering method has a large area of film formation, good film The advantages of thickness uniformity and reproducibility have been applied as a film-forming technology for mass production.

When a voltage is applied to the organic light-emitting diode, part of the light emitted from the organic layer 36 is radiated to the outside through the direction of the transparent electrode 42, and part is radiated to the outside through the metal reflective layer 32. At the same time, the light from the outside The incident light 100 is also reflected by the metal reflective layer 32, which will reduce the contrast of the display panel.

As shown in FIG. 4, when external light 100 passes through the translucent electron injection cathode layer 38, a part of the incident light is reflected by the translucent electron injection cathode layer 38 to generate the first reflected light 200; as for the other part of the incident light, it will The translucent electrons are injected into the cathode layer 38 until the metal reflective layer 32 is reflected and the second reflected light 300 is formed. It should be noted that in the present invention, the thickness 1d of the organic layer 36 and the thickness 1d′ of the transparent anode electrode 34 can be adjusted so that the first reflected light 200 reflected by the semi-transparent electron injection cathode layer 38 can be compared with the first reflected light 200 reflected by the metal reflective layer 32. The reflected second reflected light 300 produces a 180° phase difference, thereby causing destructive interference, thereby reducing the reflection of the external light 100 , reducing the interference of external incident light, and improving the contrast of the components.

Embodiment two

As shown in FIG. 6 , the organic light-emitting diode that reduces the reflection of external light in the present invention includes a substrate 50 , a metal anode electrode 52 formed on the substrate 30 , an organic layer 54 formed on the metal anode electrode 52 , and an organic layer 54 formed on the organic layer 54 . The translucent injection cathode layer 56 on the top, the buffer layer 58 formed on the semitransparent injection cathode layer 56 and the transparent electrode 60 formed on the buffer layer 58 .

The thickness of the translucent injected cathode layer 52 is about 0.5-5 nm.

The organic light-emitting diode (OLED) process for reducing external light reflection of the present invention comprises the following steps:

step one

As shown in Figure 5, a substrate 50 is provided

The material of the substrate 50 can be selected from appropriate materials that are light-transmitting or opaque, so as to carry organic light-emitting diode elements;

step two

Forming the metal anode electrode 52

Select nickel, palladium, platinum, gold, silver, chromium and other metals or alloys with better conductivity and larger work function, vacuum evaporation method, ionization evaporation method/sputtering with dry resistance heating or electron beam heating Method or wet electroless plating method is equal to directly forming the metal anode electrode 52 on the substrate 50;

step three

Form the organic layer 54

Fluorescent or phosphorescent pigments or complex materials selected from Alq, NPB, CuPc, C545T, DCJTB, CBP, Balq, Ir(ppy) _3, etc., and vacuum evaporation method, electron beam heating vacuum evaporation method, ion Chemical evaporation method, organic molecular wire evaporation method, plasma polymerization method, vacuum evaporation polymerization method, immersion coating method, spin coating method, Langmuir-Blodgett (LB) thin film method, Sol-Gel method or electrolytic polymerization method, etc. forming an organic layer 54 on the metal anode electrode 52;

step four

Forming a translucent electron injection cathode layer 56

Select a material with better conductivity and more stability, such as lithium fluoride (LiF) metal compound as the material of the electron injection cathode layer 56, to form a translucent electron injection cathode layer 56 on the organic layer 54 by sputtering or vapor deposition, and then The combination of vapor-deposited aluminum metal can effectively reduce the driving voltage value, and the thickness must be thin enough to have a certain degree of light transmission to form a translucent state. The atomic layer thickness is about 0.5-5nm. In addition, magnesium silver (Mg-Ag), aluminum lithium (Al-Li) alloy electrode materials also have the same effect;

step five

Form buffer layer 58

On the translucent electron injection cathode layer 56, a buffer layer 58 is formed from organic materials such as CuPc; in order to produce a protective effect when sputtering the next layer of transparent electrodes, because high-energy sputtering may damage the organic layer. , then it is necessary to add this buffer layer 58 to absorb most of the energy;

step six

Form the transparent electrode 60

It is selected from transparent conductive materials such as indium tin oxide and indium zinc oxide, and forms a transparent electrode 60 on the buffer layer 58 by sputtering, electron beam evaporation, etc.; The advantages of thickness uniformity and reproducibility have been applied as a film-forming technology for mass production.

When a voltage is applied to the organic light-emitting diode, part of the light emitted from the organic layer 54 is radiated to the outside through the direction of the transparent electrode 60, and part is radiated to the outside through the metal anode electrode 52. At the same time, the light from the outside The incident light 400 is also reflected by the metal anode electrode 52, which reduces the contrast of the display panel.

As shown in Figure 6, when the external light 400 passes through the translucent electron injection cathode layer 56, a part of the incident light is reflected by the translucent electron injection cathode layer 56 to generate the first reflected light 500; as for the other part of the incident light, it will The translucent electrons are injected into the cathode layer 56 until the metal anode electrode 52 is reflected and the second reflected light 600 is formed. It is worth noting that in the present invention, the thickness 1p of the organic layer 54 can be adjusted so that the first reflected light 500 reflected by the semi-transparent electron injection cathode layer 56 and the second reflected light 600 reflected by the metal anode electrode 52 generate 180 ° phase difference, thereby causing destructive interference, thereby reducing the reflection of the external light 400, and achieving the effect of improving the contrast of the components.

The present invention has the following advantages:

1. The conventional method of adding a black cathode to absorb external incident light can reduce the interference of external incident light, but it may also absorb light emitted by organic materials, reducing the luminous efficiency of organic light-emitting diodes. Because the present invention does not increase the black cathode (black cathode), the luminous efficiency is better than the conventional technology.

2. The conventional addition of a black cathode to absorb external incident light not only increases the difficulty of the manufacturing process, but also increases the cost and reduces the output per unit time. In the present invention, by adjusting the thickness of the organic layer and the transparent anode electrode, the interference of external incident light can be reduced and the contrast of the display can be improved.

Claims (10)

1. An organic light-emitting diode process for reducing the reflection of external light, which includes providing a substrate; it is characterized in that it also includes forming a metal reflective layer on the substrate, forming a transparent anode electrode on the metal reflective layer, and forming a transparent anode electrode on the transparent anode electrode. An organic layer, forming a translucent electron injection cathode layer on the organic layer and forming a transparent electrode. 2. The organic light-emitting diode process for reducing the reflection of external light according to claim 1, characterized in that the semi-transparent electron injection cathode layer is formed of organic materials so as to produce a protective buffer when the transparent electrode is sputtered. layer; the transparent electrode is formed on the buffer layer. 3. The organic light-emitting diode process for reducing external light reflection according to claim 1, characterized in that the thickness of the semi-transparent electron injection cathode layer is about 0.5-5 nm. 4. An organic light-emitting diode process for reducing the reflection of external light, which includes providing a substrate; it is characterized in that it also includes forming a metal anode electrode on the substrate, forming an organic layer on the metal anode electrode, and forming a semi-transparent electrode on the organic layer. Electrons are injected into the cathode layer and form a transparent electrode. 5. The organic light-emitting diode process for reducing the reflection of external light according to claim 4, characterized in that the translucent electron injection cathode layer is formed of organic materials so as to produce a protective buffer when the transparent electrode is sputtered. layer; the transparent electrode is formed on the buffer layer. 6. The organic light-emitting diode process for reducing external light reflection according to claim 4, characterized in that the thickness of the semi-transparent electron injection cathode layer is about 0.5-5 nm. 7. An organic light-emitting diode that reduces the reflection of external light, which includes a substrate and a transparent anode electrode; it is characterized in that a metal reflective layer is formed on the substrate; the transparent anode electrode is formed on the metal reflective layer; An organic layer is formed on the anode electrode, a translucent electron injection cathode layer is formed on the organic layer, a buffer layer is formed on the semitransparent electron injection cathode layer, and a transparent electrode is formed on the buffer layer. 8. The organic light-emitting diode for reducing external light reflection according to claim 7, characterized in that the thickness of the semi-transparent electron injection cathode layer is about 0.5-5 nm. 9. An organic light-emitting diode that reduces the reflection of external light, which includes a substrate and an anode electrode; it is characterized in that the anode electrode is a metal anode electrode, an organic layer is formed on the transparent anode electrode, and a semi-conductive layer is formed on the organic layer. A transparent electron injection cathode layer is formed, a buffer layer is formed on the translucent electron injection cathode layer, and a transparent electrode is formed on the buffer layer. 10. The organic light-emitting diode for reducing the reflection of external light according to claim 9, characterized in that the thickness of the semi-transparent electron injection cathode layer is about 0.5-5 nm.

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