CN103579520B - Organic light emitting diodde desplay device - Google Patents

Abstract

The invention discloses an organic light-emitting diode display device, which comprises an anode, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer and a cathode. Made of materials with a refractive index greater than or equal to 2.4. In the organic light emitting diode display device of the present invention, an anti-reflection layer is prepared on the translucent metal layer to change the distribution of light reflection and transmission energy and increase the luminous flux of transmitted light. In addition, by selecting a material with a refractive index greater than or equal to 2.4 to make the anti-reflection layer, the color variation of the display device with the viewing angle can be effectively reduced, thereby improving the display quality of the display device.

Description

Organic Light Emitting Diode Display Devices

technical field

The invention relates to the technical field of organic light emitting diodes, in particular to an organic light emitting diode display device.

Background technique

Organic light-emitting diode (OLED) display devices are divided into bottom-emitting devices and top-emitting devices according to the light emitting method. Bottom-emitting organic light-emitting diode display device (BOLED), indium tin oxide ITO (or indium zinc oxide IZO) as a transparent anode is grown on a glass substrate by sputtering, and the light emitted inside the device passes through the ITO ( or IZO), glass substrate injection. The display screen fabricated in this way has a relatively reduced area of the display area and a lower aperture ratio of the display screen due to the fact that the driving circuit and the display area are fabricated on the glass at the same time. Compared with ordinary bottom-emitting devices, top-emitting organic light-emitting diode display devices (TEOLED) can emit light from the top electrode due to their own structural characteristics. In active-driven OLEDs, pixel drive circuits, buses, etc. can be fabricated on the display area, thereby avoiding the problem of competition between the driving circuit and the display area, so that the aperture ratio of the device is greatly improved. Top-emitting devices can also be fabricated on silicon-based substrates, thereby making microdisplays on silicon. Because the display screen made of top-emitting devices also has the advantages of high resolution and high information content, this makes top-emitting devices attract more and more people's attention in the past two years, and has become a research hotspot.

In top-emitting devices, transparent ITO (or IZO) or translucent metals are generally used as the top cathode. Since sputtering is required to make ITO (or IZO), high-energy ITO (or IZO) particles are very destructive to the underlying organic layer, resulting in a large leakage current of the device, so a better alternative is to use translucent metal to replace ITO (or IZO) as the top cathode. The advantage is that it is easy to grow and less destructive; the disadvantage is that the light transmission of metal is relatively poor, which is not conducive to the coupling output of light, and the microcavity effect is more obvious. In the application of displays, the change of luminous intensity and color with viewing angle is the largest question.

In the Chinese invention patent application with the publication number _CN101944570 and the name "Organic Light-Emitting Display and Its Manufacturing Method", triamine derivatives, arylenediamine derivatives, CBP, and AlQ3 are used as organic covering layers to increase the output light efficiency, and limit the thickness of the organic layer to 30nm-90nm. Although this scheme obtains the maximum outgoing light intensity, it does not consider the color change under different viewing angles due to the microcavity effect.

In the Chinese invention patent application with the publication number CN101599536 and the name "Organic Light Emitting Diode Display Device", it is mentioned that the use of double-layer refraction layers is used to improve the light coupling output, and it is proposed that the first layer has a refractive index between 1.4-1.8, and the second The refractive index of the first layer is 1.1 times that of the first layer. Wherein the first refraction layer and the second refraction layer include niobium oxide Nb ₂ O ₅ , tantalum oxide Ta ₂ O ₅ , titanium oxide Ti ₂ O ₅ , silicon nitride SixNy, silicon oxide SiO ₂ , antimony oxide Sb ₂ O ₃ , oxide Aluminum Al ₂ O ₃ , Zirconia ZrO ₂ , Magnesium Oxide MgO, Hafnium Oxide HfO ₂ or synthetic polymers. The efficiency of the device is improved, but the problem of the color variation of the device with the viewing angle is still not solved.

Contents of the invention

The technical problem to be solved by the present invention is to provide an organic light emitting diode display device, which can effectively solve the problem that the color changes with the viewing angle.

In order to solve the above technical problems, the present invention provides an organic light emitting diode display device, comprising an anode, a hole transport layer, an organic light emitting layer, an electron transport layer, an electron injection layer and a cathode, and an anti-reflection layer is provided outside the cathode, The anti-reflection layer is made of a material with a refractive index greater than or equal to 2.4.

Further, the refractive index of the anti-reflection layer is greater than or equal to 2.4 and less than or equal to 2.8.

Further, the refractive index of the antireflection layer is greater than or equal to 2.4 and less than or equal to 2.6.

Further, the thickness of the anti-reflection layer is 20nm~80nm.

Further, the thickness of the anti-reflection layer is 30nm~50nm.

Further, the material of the anti-reflection layer is selected from one of Bi ₂ O ₃ , Cr ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , ZnTe, ZnSe, ZnS and ZnO.

Further, a hole injection layer is further provided between the anode and the hole transport layer.

Further, an indium tin oxide layer or an indium zinc oxide layer is further provided between the anode and the hole injection layer.

In the organic light emitting diode display device of the present invention, an anti-reflection layer is prepared on the translucent metal layer to change the distribution of light reflection and transmission energy and increase the luminous flux of transmitted light. In addition, by selecting a material with a refractive index greater than or equal to 2.4 to make the anti-reflection layer, the color variation of the display device with the viewing angle can be effectively reduced, thereby improving the display quality of the display device.

Description of drawings

FIG. 1 is a schematic structural view of an embodiment of an organic light emitting diode display device of the present invention.

In the figure: 1. anode, 2. Indium tin oxide layer, 3. hole injection layer, 4. hole transport layer, 5. organic light-emitting layer, 6. electron transport layer, 7. electron injection layer, 8. cathode, 9. anti-reflection layer.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the examples given are not intended to limit the present invention.

The basic composition of the organic light emitting diode display device of the present invention includes an anode (Anode), a hole transport layer (Hole Transport Layer, HTL), an organic light emitting layer (Emitting Material Layer, EML), an electron transport layer (Electron Transport Layer, ETL), electron injection layer (Electron Inject Layer, EIL) and cathode (Cathode), the present invention is to set at least one anti-reflection layer on the outside of the cathode, and the anti-reflection layer is made of a material with a refractive index greater than or equal to 2.4 production. The higher the refractive index of the anti-reflection layer, the better its viewing angle characteristics, but if the refractive index is too high, waveguide loss will occur, which will affect the luminous efficiency of the device. Therefore, the refractive index of the anti-reflection layer is preferably greater than or equal to 2.4 and less than or equal to 2.8, and the best refractive index is greater than or equal to 2.4 and less than or equal to 2.6. In addition, a hole injection layer (Hole Inject Layer, HIL) can be added between the anode and the hole transport layer, and an indium tin oxide ITO layer or an indium zinc oxide IZO layer can also be added between the anode and the hole injection layer .

The thickness of the anti-reflection layer will affect the light transmittance of the transparent electrode, but it is not the best light transmittance and the highest efficiency. The thickness of the anti-reflection layer is preferably between 20nm and 80nm, and the preferred thickness of the anti-reflection layer is 30nm~50nm .

FIG. 1 is a schematic structural diagram of an embodiment of an organic light emitting diode display device of the present invention. In this embodiment, the organic light emitting diode display device sequentially includes an anode 1, an indium tin oxide layer 2, a hole injection layer 3, a hole transport layer 4, an organic light emitting layer 5, an electron transport layer 6, and an electron injection layer 7 , cathode 8 and anti-reflection layer 9. In this embodiment, both the anode and the cathode are made of metallic silver. Of course, an insulating layer needs to be provided between each transmission layer and the electrodes.

For the material of the anti-reflection layer, generally as long as it is a material with a refractive index greater than 2.4, for example, it can be selected from Bi ₂ O ₃ , Cr ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , ZnTe, ZnSe, ZnS and one of ZnO.

Several specific examples are listed below to illustrate the viewing angle characteristics of the present invention.

Embodiment 1: use the ZnSe material with a refractive index of 2.58 in the red light as the anti-reflection layer of the red light device, and its device structure is: Ag/ITO/HIL/HTL/EML/ETL/EIL/Ag/ZnSe, wherein The thickness of the ZnSe anti-reflection layer is 40nm, and the change of its luminous color with the viewing angle is:

CIEx CIE 0° 0.6750 0.3247 30° 0.6716 0.3281 45° 0.6673 0.3324 60° 0.6617 0.3380

Embodiment 2: Bi ₂ O ₃ materials with a refractive index of 2.45 are used in the anti-reflection layer of red light devices in red light, and the device structure is: Ag/ITO/HIL/HTL/EML/ETL/EIL/Ag/ Bi ₂ O ₃ , where the thickness of the Bi ₂ O ₃ anti-reflection layer is 40nm, the change of its luminescent color with the viewing angle is:

CIEx CIE 0° 0.6739 0.3259 30° 0.6700 0.3297 45° 0.6663 0.3331 60° 0.6603 0.3382

As a comparative example of embodiment 1 and embodiment 2, LiF with a refractive index of 1.4 is used for the anti-reflection layer of the red light device, and its device structure is: Ag/ITO/HIL/HTL/EML/ETL/EIL/Ag /LiF, the thickness of the LiF anti-reflection layer is also 40nm, and the change of its luminous color with the viewing angle is:

CIEx CIE 0° 0.6714 0.3286 30° 0.6655 0.3340 45° 0.6432 0.3501 60° 0.6098 0.3850

Embodiment 3: TiO ₂ materials with a refractive index of 2.4 are used in the anti-reflection layer of green light devices in green light, and the device structure is: Ag/ITO/HIL/HTL/EML/ETL/EIL/Ag/TiO ₂ , where the thickness of the TiO ₂ anti-reflection layer is 80nm, and the change of its luminescent color with the viewing angle is:

CIEx CIE 0° 0.1760 0.7186 30° 0.1713 0.7068 45° 0.1706 0.6996 60° 0.1713 0.6915

Embodiment 4: adopt the ZnTe material of refractive index 2.8 to be used in the anti-reflection layer of green light device in green light, its device structure is: Ag/ITO/HIL/HTL/EML/ETL/EIL/Ag/ZnTe, wherein The thickness of the ZnTe anti-reflection layer is 80nm, and the change of its luminescent color with the viewing angle is:

CIEx CIE 0° 0.1716 0.7162 30° 0.1651 0.7059 45° 0.1640 0.6952 60° 0.1646 0.6860

As a comparative example of Examples 3 and 4, AlQ ₃ with a refractive index of 1.75 is used for the anti-reflection layer of the green light device, and its device structure is: Ag/ITO/HIL/HTL/EML/ETL/EIL/Ag/ AlQ ₃ , the thickness of the AlQ ₃ anti-reflection layer is also 80nm, and the change of its luminescent color with the viewing angle is:

CIEx CIE 0° 0.1899 0.7251 30° 0.1553 0.7122 45° 0.1420 0.6846 60° 0.1401 0.6647

It can be seen from the above examples that the viewing angle performance of the organic light emitting diode display device of the present invention is much higher than that of using a material with a refractive index less than 2.4 as the anti-reflection layer.

The above-mentioned embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention shall be determined by the claims.

Claims (6)

1. An organic light emitting diode display device, comprising an anode (1), a hole transport layer (4), an organic light emitting layer (5), an electron transport layer (6), an electron injection layer (7) and a cathode (8), It is characterized in that an anti-reflection layer (9) is provided outside the cathode, and the anti-reflection layer (9) is made of a material with a refractive index greater than or equal to 2.45; the thickness of the anti-reflection layer (9) is 20nm~ 80 nm; the material of the anti-reflection layer (9) is selected from one of Bi ₂ O ₃ , Cr ₂ O ₃ , B ₂ O ₃ , ZrO ₂ , ZnTe and ZnSe. 2. The organic light emitting diode display device according to claim 1, characterized in that, the refractive index of the anti-reflection layer (9) is greater than or equal to 2.45 and less than or equal to 2.8. 3. The organic light emitting diode display device according to claim 2, characterized in that, the refractive index of the antireflection layer (9) is greater than or equal to 2.45 and less than or equal to 2.6. 4. The organic light emitting diode display device according to claim 1, characterized in that, the thickness of the antireflection layer (9) is 30nm~50nm. 5. The organic light emitting diode display device according to claim 1, characterized in that a hole injection layer (3) is further provided between the anode (1) and the hole transport layer (4). 6. The organic light emitting diode display device according to claim 5, characterized in that an indium tin oxide layer (2) or an indium zinc oxide layer (2) is further provided between the anode (1) and the hole injection layer (3). object layer.