WO2019051878A1

WO2019051878A1 - Oled device structure

Info

Publication number: WO2019051878A1
Application number: PCT/CN2017/103170
Authority: WO
Inventors: 倪晶; 徐湘伦; 李先杰
Original assignee: 武汉华星光电半导体显示技术有限公司
Priority date: 2017-09-12
Filing date: 2017-09-25
Publication date: 2019-03-21
Also published as: CN107425140A

Abstract

An OLED device structure, comprising a substrate, and an anode layer (10), a hole injection layer (11), a hole transport layer (12), an emissive layer (13), an electron transport layer (14), an electron injection layer (15), and a cathode layer (16) that are provided on the substrate, an organic anti-reflection layer (401) being provided between the cathode layer and the electron injection layer, a refractive index value n of the organic anti-reflection layer falling within the range of 1.5-1.9. The structure can improve the emissive efficiency of red sub-pixels, green sub-pixels, and blue sub-pixels.

Description

OLED device structure

The present application claims the priority of the Chinese Patent Application, filed on Sep. 12, 2017, the entire disclosure of which is hereby incorporated by reference. .

Technical field

The present invention relates to the field of display, and in particular to an OLED device structure.

Background technique

Organic Light Emitting Diode (OLED) display is a promising flat panel display technology with self-illumination, simple structure, ultra-thin, fast response, wide viewing angle, low power consumption and flexible display. And other characteristics. At present, OLED displays have been favored by major display manufacturers, and become the third generation display after CRT (Cathode Ray Tube) display and liquid crystal display (LCD).

Since the organic light-emitting device is basically composed of two layers of organic material thin films between the two electrodes, as the research progresses, the current multi-layer structure is gradually formed, as shown in FIG. 1, showing the existing one. Schematic diagram of the structure of an OLED device. In this configuration, it includes a substrate, and an anode layer 10, a hole injection layer (HIL) 11, a hole transport layer (HTL) 12, an emission layer (EML) 13, and an electron transport layer (ETL) placed on the substrate. 14. An electron injection layer (EIL) 15 and a cathode 16.

The total thickness of the organic material and the wavelength of the light are of the same order of magnitude, generally within a few hundred nanometers, and the optical effects of light, such as reflection, refraction, absorption, re-emission, etc. between the layers, can significantly affect the photoelectric properties of the device. For the top-emitting device, its strong resonant cavity structure can narrow the electroluminescence spectrum and improve the luminous efficiency and color purity. It is the mainstream OLED device structure used in small-sized OLED displays. Increasing the luminous efficiency of the OLED can effectively reduce the power consumption of the display and effectively extend the standby time. The patent proposes to insert a light anti-reflection film between the cathode of the top emission device and the electron injection layer, which can greatly improve the luminous efficiency of the OLED.

For the top-emitting OLED device, the light transmittance of the metal cathode layer is poor, which is disadvantageous for the coupling output of light.

Summary of the invention

The technical problem to be solved by the present invention is to provide an OLED device structure, which adds an organic antireflection film between the metal cathode layer and the electron injection layer, and simultaneously improves the red sub-pixel, the green sub-pixel and the blue sub-pixel. Luminous efficiency.

In order to solve the above technical problem, an aspect of an embodiment of the present invention provides an OLED device structure including a substrate and an anode layer, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron disposed on the substrate. The injection layer and the cathode layer are provided with an organic antireflection layer between the cathode layer and the electron injection layer, and the organic antireflection layer has a refractive index n value of between 1.5 and 1.9.

The illuminating layer includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, and the organic anti-reflection layer corresponding to the red sub-pixel, the green sub-pixel, and the blue sub-pixel has different thicknesses, wherein The thickness of the organic antireflection layer corresponding to the sub-pixel> the thickness of the organic anti-reflection layer corresponding to the green sub-pixel> the thickness of the organic anti-reflection layer corresponding to the blue sub-image;

The anode layer is a reflective metal including an intermediate position and a conductive oxide on both sides of the reflective metal, wherein the conductive oxide is at least ITO or IZO; and the reflective metal is Ag, Al, Cu, Au, or an alloy of the above metals. .

Wherein, the organic antireflection layer is an organic small molecule comprising a metal chelate or an aromatic amine.

Wherein, the thickness of the organic antireflection layer is between 0.5 nm and 30 nm.

The substrate includes a base substrate and a thin film transistor disposed on the base substrate, and the substrate is a transparent glass substrate or a transparent flexible material substrate.

Wherein, the hole injection layer material is an organic small molecule hole injection material, a polymer hole injection material or a metal oxide hole injection material, and the film thickness thereof is between 1 nm and 100 nm.

Wherein, the hole transport layer material is an organic small molecule hole transport material or a polymer hole transport material, and the film thickness thereof is between 10 nm and 100 nm.

Wherein, the material of the electron transport layer is a metal complex material or an imidazole electron transport material; and the film thickness thereof is between 10 nm and 100 nm.

Wherein, the electron injecting layer material is a metal complex, an alkali metal and a salt thereof or an alkaline earth metal and a salt thereof; and the film thickness thereof is between 0.5 nm and 10 nm.

Correspondingly, an embodiment of the present invention further provides an OLED device structure, including a substrate and an anode layer, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron disposed on the substrate. An injection layer and a cathode layer, an organic antireflection layer is disposed between the cathode layer and the electron injection layer, and the organic antireflection layer has a refractive index n value between 1.5 and 1.9;

The illuminating layer includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, and the organic anti-reflection layer corresponding to the red sub-pixel, the green sub-pixel, and the blue sub-pixel has different thicknesses, wherein the red sub-pixel corresponds to The thickness of the organic antireflection layer > the thickness of the organic antireflection layer corresponding to the green subpixel > the thickness of the organic antireflection layer corresponding to the blue subimage.

According to the technical proposal of the present invention, an organic antireflection film is added between the organic injection layer and the metal cathode layer, and the n value is between 1.7 and 1.9. The simulation results show that the red layer can be significantly improved after the layer structure is added. Luminous efficiency of sub-pixels, green sub-pixels, and blue sub-pixels;

Meanwhile, the organic antireflection layer corresponding to the red sub-pixel, the green sub-pixel, and the blue sub-pixel has different thicknesses, wherein the thickness of the organic anti-reflection layer corresponding to the red sub-pixel > the organic anti-reflection layer corresponding to the green sub-pixel The thickness>the thickness of the organic antireflection layer corresponding to the blue sub-image can further improve the luminous efficiency of the red sub-pixel, the green sub-pixel, and the blue sub-pixel.

DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are only It is a certain embodiment of the present invention, and other drawings can be obtained from those skilled in the art without any creative work.

1 is a schematic structural view of a conventional OLED device;

2 is a schematic structural view of an embodiment of an OLED device structure provided by the present invention;

Figure 3 is a schematic view of the optical simulation effect of Figure 2;

4 is a schematic structural view of another embodiment of an OLED device structure provided by the present invention;

Figure 5 is a graph showing the relationship between the thickness of the antireflection layer and the improvement of current efficiency performance of the different lights in Figure 4.

Detailed ways

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention. Wai.

In this context, it is also to be noted that in order to avoid obscuring the invention by unnecessary detail, only the structures and/or processing steps closely related to the solution according to the invention are shown in the drawings, and the Other details that are not relevant to the present invention.

As shown in FIG. 2, a schematic structural view of an embodiment of an OLED device structure provided by the present invention is shown. In this embodiment, the OLED device structure includes a substrate (not shown) and is disposed on the substrate. The anode layer 10, the hole injection layer 11, the hole transport layer 12, the light-emitting layer 13, the electron transport layer 14, the electron injection layer 15, and the cathode layer 16 are provided with an organic increase between the cathode layer 16 and the electron injection layer 15. The transparent layer 401 has a refractive index n value of between 1.5 and 1.9, and the organic anti-reflection layer 401 has a thickness of not more than 30 nm, for example, between 0.5 nm and 30 nm; wherein the light-emitting layer comprises The red sub-pixel, the green sub-pixel, and the blue sub-pixel are determined by selecting the luminescent material of the luminescent layer 13. For example, the luminescent layer of the red sub-pixel is selected from a luminescent material that emits red light, and the illuminating of the green sub-pixel The layer is made of a luminescent material that emits green light; in FIG. 2, the leftmost layer of the luminescent layer is a red luminescent layer, the middle is a green luminescent layer, and the rightmost side is a blue luminescent layer.

In one example, the organic anti-reflection layer 401 is an organic small molecule (such as 8-hydroxyquinolate lithium LiQ, etc.) containing a metal chelate or an aromatic amine, or an organic high molecular polymer, and the aforementioned single or A composite of multiple materials.

As shown in FIG. 3, it is a schematic diagram of the optical simulation effect in FIG. 2. In one embodiment of the present invention, the OLED device using the structure of FIG. 2 is simulated by using professional optical simulation software (Setfos), in which the organic The antireflection layer 401 is exemplified by a LiQ material (lithium hydroxyquinolate), and a 5 nm thick LiQ material is selected for the organic antireflection layer corresponding to the red sub-pixel, the green sub-pixel, and the blue sub-pixel to perform simulation. The simulated data is shown in Figure 3. Among them, the leftmost one shows the contrast of the light-emitting spectrum of the anti-reflection film and the anti-reflection film in the blue sub-pixel, and the contrast of the light-emitting spectrum of the anti-reflection film and the anti-reflection film in the green sub-pixel is shown in the middle. The rightmost side shows the contrast of the light-emitting spectrum of the anti-reflection film and the anti-reflection film in the red sub-pixel. It can be seen that the addition of the organic anti-reflection film 401 of the layer can improve the performance of the OLED device, and the gain effect on the blue light and the red light is most obvious. Therefore, for the red sub-pixel, the green sub-pixel and the blue sub-pixel in the OLED device, the same organic anti-reflection layer thickness is selected, so that the overall efficiency of the OLED device can be significantly improved.

It can be understood that in the OLED device shown in FIG. 2, the layer structure can adopt the following materials:

The substrate includes a base substrate and a thin film transistor disposed on the base substrate, which may be a transparent glass substrate or a transparent flexible material substrate, the thin film transistor including at least a semiconductor layer, an insulating layer, a source, a drain, and Gate.

The anode layer 10 is a conductive oxide-reflective metal-conductive oxide structure, specifically, in a layer structure, including a reflective metal at an intermediate position and a conductive oxide on both sides of the reflective metal, wherein the conductive oxide Including but not limited to ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide), the film thickness is between 10 nm and 50 nm; the reflective metal is Ag, Al, Cu, Au, etc. Or an alloy of the above metals having a thickness between 50 nm and 200 nm. Generally, the three light emitting units of each pixel unit can be individually controlled by the driving circuit to realize individual driving of each light emitting unit, specifically, the anode layer electrical properties of each of the red sub-pixel, the green sub-pixel and the blue sub-pixel. Connected to a thin film transistor, each of which is driven by a thin film transistor control.

The material of the hole injection layer 11 is an organic small molecule hole injection material (such as HATCN), a polymer hole injection material (such as PEDOT: PSS, etc.) or a metal oxide hole injection material (such as MoO _3, etc.). Its film thickness is between 1 nm and 100 nm.

The material of the hole transport layer 12 is an organic small molecule hole transport material (such as NPB, TAPC, etc.) or a polymer hole transport material (such as Poly-TPD, etc.), and the film thickness thereof is between 10 nm and 100 nm.

The blue light-emitting layer in the light-emitting layer 13 adopts a method in which an organic host material is doped with an organic blue light guest material, wherein a doping mass ratio of the host material to the guest material is: host material: guest material=1: (0.01-1) The organic blue guest material is a blue organic fluorescent material or a blue organic phosphorescent material.

When the organic blue guest material is an organic fluorescent material, the organic host material is an anthracene derivative (such as MADN, etc.) or a wide band gap organic material (such as mCP, CBP, etc.); the organic blue guest material is an organic phosphorescent material. The organic host material is a wide band gap organic material (such as mCP and CBP, etc.).

The material of the electron transport layer 14 is a metal complex material (for example, Alq ₃ or the like) or an imidazole electron transport material (such as TPBi or the like); and the film thickness thereof is between 10 nm and 100 nm.

The material of the electron injecting layer 15 is a metal complex (such as lithium hydroxyquinolate (Liq)), an alkali metal and salts thereof (such as Li, Na, K, Rb, Cs, LiF, Li ₂ CO ₃ , LiCl). , NaF, Na ₂ CO ₃ , NaCl, CsF, Cs ₂ CO ₃ , CsCl, etc.) or alkaline earth metals and their salts (eg Mg, Ca, Sr, Ba, CaF ₂ , CaCO ₃ , SrF ₂ , SrCO ₃ , BaF) ₂ , BaCO _{3 ,} etc.); its film thickness is between 0.5 nm and 10 nm.

The metal cathode layer 16 is a low work function metal material (such as Li, Mg, Ca, Sr, La, Ce, Eu, Yb, Al, Cs, Rb, Ag, etc.), a conductive oxide or an alloy of the above metals, The film thickness is between 10 nm and 20 nm, wherein the conductive oxide is ITO or IZO or the like.

FIG. 4 is a schematic structural view of another embodiment of an OLED device structure provided by the present invention; in this embodiment, the main difference from the embodiment shown in FIG. 2 is that, among the red sub-pixels The organic anti-reflection layer 401 corresponding to the green sub-pixel and the blue sub-pixel has different thicknesses, that is, the organic anti-reflection layer 401 disposed directly above the red, green, and blue light-emitting layers has different thicknesses. As can be seen from the figure, the thickness of the organic antireflection layer corresponding to the red sub-pixel > the thickness of the organic anti-reflection layer corresponding to the green sub-pixel > the thickness of the organic anti-reflection layer corresponding to the blue sub-image. The structure shown in FIG. 4 utilizes the microcavity effect of the top emission device to adjust the cavity length by adjusting the thickness corresponding to the different colors of the antireflection layer, thereby finding an appropriate microcavity to enhance device performance.

Similarly, the organic antireflection layer of the LiQ material is taken as an example to simulate the organic antireflection layers of different thickness corresponding to the red sub-pixel, the green sub-pixel and the blue sub-pixel. The optimal thickness of the organic antireflection layer corresponding to the red sub-pixel, the green sub-pixel and the blue sub-pixel can be obtained, as shown in FIG. 5, from which the most organic anti-reflection layer corresponding to the blue sub-pixel can be seen. The good thickness is 13%, the blue index performance is increased by 22%; the optimal thickness of the organic antireflection layer corresponding to the green sub-pixel is 7nm, and the current efficiency performance is improved by 3%, corresponding to the red sub-pixel. The optimum thickness of the organic anti-reflection layer is 22 nm, and its current efficiency performance is improved by 46.8%. Among them, the green sub-pixel and the red sub-pixel are provided with an organic anti-reflection layer and a current efficiency value for setting the anti-reflection layer (luminous flux per unit area, Cd/ A), you can refer to the ordinate value on the right side of Figure 5; the blue light index is the ratio of current efficiency to color coordinate y (Cd/A/CIEY), the blue sub-pixel is set with the organic anti-reflection layer and the blue light for setting the anti-reflection layer For the index value, refer to the ordinate value on the left side of Figure 5.

Embodiments of the present invention have the following beneficial effects:

The technical solution of the invention increases the organic anti-reflection between the organic injection layer and the metal cathode layer The film has an n value between 1.7 and 1.9. The simulation results show that the light-emitting efficiency of the red sub-pixel, the green sub-pixel and the blue sub-pixel can be significantly improved after the layer structure is added;

It should be noted that, in this context, relational terms such as first and second are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply these entities or operations. There is any such actual relationship or order between them. Furthermore, the term "comprises" or "comprises" or "comprises" or any other variations thereof is intended to encompass a non-exclusive inclusion, such that a process, method, article, or device that comprises a plurality of elements includes not only those elements but also Other elements, or elements that are inherent to such a process, method, item, or device. An element that is defined by the phrase "comprising a ..." does not exclude the presence of additional equivalent elements in the process, method, item, or device that comprises the element.

The above description is only a specific embodiment of the present application, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present application. It should be considered as the scope of protection of this application.

Claims

An OLED device structure comprising a substrate and an anode layer, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer and a cathode layer disposed on the substrate, wherein the cathode layer and the electron An organic antireflection layer is disposed between the injection layers, and the organic antireflection layer has a refractive index n value between 1.5 and 1.9.
The OLED device structure according to claim 1, wherein the light emitting layer comprises a red sub-pixel, a green sub-pixel and a blue sub-pixel, wherein the red sub-pixel, the green sub-pixel and the blue sub-pixel correspond to The organic antireflection layer has different thicknesses, wherein the thickness of the organic antireflection layer corresponding to the red subpixel> the thickness of the organic antireflection layer corresponding to the green subpixel> the thickness of the organic antireflection layer corresponding to the blue subimage.
An OLED device structure according to claim 2, wherein said organic antireflection layer has a thickness of between 0.5 nm and 30 nm.
An OLED device structure according to claim 3, wherein said organic antireflection layer is a material comprising a metal chelate or an organic small molecule of an aromatic amine.
The OLED device structure according to claim 4, wherein the substrate comprises a base substrate and a thin film transistor disposed on the base substrate, the substrate being a transparent glass substrate or a transparent flexible material substrate.
An OLED device structure according to claim 3, wherein said anode layer comprises a reflective metal at an intermediate position and a conductive oxide on both sides of the reflective metal, wherein the conductive oxide is at least ITO or IZO; It is Ag, Al, Cu, Au, or an alloy of the above metals.
The OLED device structure according to claim 4, wherein the hole injecting layer material is an organic small molecule hole injecting material, a polymer hole injecting material or a metal oxide hole injecting material, and the film thickness thereof is Between 1 nm and 100 nm.
The OLED device structure according to claim 4, wherein the hole transport layer material is an organic small molecule hole transport material or a polymer hole transport material having a film thickness of between 10 nm and 100 nm.
The OLED device structure according to claim 4, wherein the material of the electron transport layer is a metal complex material or an imidazole electron transport material; the film thickness is 10 nm to Between 100nm.
The OLED device structure according to claim 4, wherein the electron injecting layer material is a metal complex, an alkali metal and a salt thereof or an alkaline earth metal and a salt thereof; and the film thickness is between 0.5 nm and 10 nm. .
An OLED device structure comprising a substrate and an anode layer, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer and a cathode layer disposed on the substrate, wherein the cathode layer and the electron An organic antireflection layer is disposed between the injection layers, and the refractive index n of the organic antireflection layer is between 1.5 and 1.9;

The illuminating layer includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, and the organic anti-reflection layer corresponding to the red sub-pixel, the green sub-pixel, and the blue sub-pixel has different thicknesses, wherein the red sub-pixel corresponds to The thickness of the organic antireflection layer>the thickness of the organic antireflection layer corresponding to the green subpixel>the thickness of the organic antireflection layer corresponding to the blue subimage;

The anode layer includes a reflective metal at an intermediate position and a conductive oxide on both sides of the reflective metal, wherein the conductive oxide is at least ITO or IZO; and the reflective metal is Ag, Al, Cu, Au, or an alloy of the above metals.
The OLED device structure according to claim 11, wherein the organic antireflection layer is a material of a small organic molecule comprising a metal chelate or an aromatic amine.
An OLED device structure according to claim 12, wherein said organic antireflection layer has a thickness of between 0.5 nm and 30 nm.
The OLED device structure according to claim 13, wherein the substrate comprises a base substrate and a thin film transistor disposed on the base substrate, the substrate being a transparent glass substrate or a transparent flexible material substrate.
The OLED device structure according to claim 14, wherein the hole injecting layer material is an organic small molecule hole injecting material, a polymer hole injecting material or a metal oxide hole injecting material, and the film thickness thereof is Between 1 nm and 100 nm.
The OLED device structure according to claim 15, wherein the hole transport layer material is an organic small molecule hole transport material or a polymer hole transport material having a film thickness of between 10 nm and 100 nm.
An OLED device structure according to claim 16 wherein said electron transport The material of the layer is a metal complex material or an imidazole electron transport material; the film thickness is between 10 nm and 100 nm.
The OLED device structure according to claim 17, wherein the electron injecting layer material is a metal complex, an alkali metal and a salt thereof or an alkaline earth metal and a salt thereof; and the film thickness is between 0.5 nm and 10 nm. .