CN110783486A - A display panel suitable for under-screen cameras - Google Patents

Abstract

The invention discloses a display panel suitable for an under-screen camera. The display panel includes a driving backplane, an anode, a hole transport layer, a light-emitting layer, an electron transport layer and a cathode; the display panel is divided into a display a region and a display b region; the cathode of the display a region is a high transmittance cathode, which emits light The layer is a quantum dot light-emitting layer, and an under-screen camera is arranged below the display area a; the cathode of the display area b is a low transmittance cathode, and the light-emitting layer is an OLED organic light-emitting layer. The present invention proposes a new and suitable display device structure and display panel design of the under-screen camera, which can simultaneously achieve high color purity display performance and high transparency of the camera area, and achieve a "true" full screen with superior performance.

Description

A display panel suitable for under-screen cameras

technical field

The invention belongs to the field of display technology, and in particular, relates to a display panel suitable for an under-screen camera.

Background technique

Due to the broad intrinsic spectrum of OLED, the spectrum has shoulder peaks, the spectrum cannot be narrowed, and the color purity is poor. Therefore, AMOLED mobile phones and wearable products all adopt the top-emission AMOLED device structure, that is, the light of the organic light-emitting layer is emitted from the cathode side, and the cathode has a certain degree of impermeability, thereby forming an optical microcavity between the electrodes, and the light is in the microcavity. The mid-vibration coupling produces a narrowed spectrum, meeting the demands of everyday consumer products with high color purity (Figure 1, Figure 2).

In specific design and production, increasing the thickness of the cathode can result in a narrowed and enhanced spectrum. In this way, there is a dilemma in the requirements for the cathode in actual production: if the cathode is too thin, the microcavity effect is too weak, and the OLED inherently broad spectrum is presented, and the spectrum has a shoulder peak, and the spectrum cannot be narrow. If the cathode is too thick, the transmittance of the AMOLED screen will be affected (Figure 3). Therefore, the thickness and process window of the conventional cathode are very small, that is, it is made into a semi-transparent nano-scale film, sacrificing a certain transmittance, and maintaining a certain micro-cavity function of narrowing the spectrum.

At present, the demand for screen-to-body ratio of smartphone screens is getting higher and higher. How to put the camera under the screen to provide a higher screen-to-body ratio has become a technical difficulty for various screen manufacturers (Figure 4). Since different areas of the OLED display screen have different transmittance requirements, the color purity caused by the thickness of the OLED cathode conflicts with the transmittance requirements, and the camera effect is poor, requiring a lot of image processing corrections (Figure 5).

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the prior art, the present invention proposes a new and suitable display device structure and display panel design of the under-screen camera, which simultaneously achieves high color purity display performance and high transparency in the camera area, and achieves excellent performance. "True" full screen.

The technical solutions of the present invention are specifically introduced as follows.

A display panel suitable for an under-screen camera, comprising a driving backplane, an anode, a hole transport layer, a light-emitting layer,

Electron transport layer and cathode; the display panel is divided into display a area and display b area; the cathode of display a area is a high transmittance cathode, the light-emitting layer is a quantum dot light-emitting layer, and an under-screen camera is set under display a area; display b The cathode of the region is a low transmittance cathode, and the light-emitting layer is an OLED organic light-emitting layer.

In the present invention, the cathodes of the display area a and the display area b are made of the same material, and the cathode thickness of the display area a is smaller than that of the display area.

Cathode thickness in b region.

In the present invention, the cathodes that display the area a and the area b are made of different materials, and the transmittance of the cathode material of the area a is displayed.

Greater than the transmittance of the cathode material showing the b region.

In the present invention, the transmittance of the high transmittance cathode showing the a region is greater than 70%, and the transmittance of the low transmittance cathode showing the b region is between 35% and 55%.

In the present invention, the quantum dot diameter of the quantum dot light-emitting layer is between 2-20 nm, and the diameter of the quantum dots is between IV, II-VI, IV-VI or III-V.

Elemental composition; quantum dots are selected from silicon quantum dots, germanium quantum dots, cadmium sulfide quantum dots, cadmium selenide quantum dots, cadmium telluride quantum dots, zinc selenide quantum dots, indium phosphide quantum dots, indium arsenide quantum dots or Any of perovskite quantum dots.

In the present invention, the display a region and the display b region use the same driving backplane and anode, while the hole transport layer, light emitting layer,

The electron transport layer and the cathode are separated from each other, and the display panel with the same light and color performance is matched by the difference of the respective diode structures.

In the present invention, the display a region and the display b region use the same driving backplane, anode, hole transport layer and electron transport layer,

The light-emitting layer and the cathode are separated separately, and the balance is compensated by the difference between the driving signals of the display a area and the display b area, or the display panel with the same light and color performance is matched by screening the light-emitting layer materials with similar light and color properties.

In the present invention, the display a region is one or two.

Compared with the prior art, the beneficial effects of the present invention are:

1. The present invention can simultaneously achieve the display performance of high color purity and the high transparency of the camera area, meet the requirements of the camera for the high transparency of the display area, and the requirements of the color purity of the overall display screen, thereby realizing the “true” performance with superior performance. Full screen.

2. The present invention can be applied to different display fields by deforming the division shape and area of the display area a (high transparency) and the display area b.

Description of drawings

FIG. 1 is a comparison diagram of the luminescence spectrum of the traditional OLED structure and the microcavity OLED structure. The figure shows: Compared with the traditional OLED structure, the spectrum under the microcavity OLED structure is narrowed, and the color purity can be improved.

FIG. 2 is a specific film stacking diagram of the top-emission microcavity OLED structure. From bottom to top in the figure are the glass substrate, the driving tube unit, the reflective electrode, the hole transport layer, the light-emitting layer, the electron transport layer, the semi-transparent cathode, the protective layer, and the encapsulating glass layer.

FIG. 3 is a graph showing the dependence of the transmittance of the metal cathode on the thickness of the metal cathode. The figure shows that the thicker the cathode film layer, the greater the transmittance.

Figure 4 shows the trend of demand for display screens in the smartphone market. The figure shows that the market demand for screen-to-body ratio is increasing, and the camera must be placed under the screen, and it has become a trend to achieve a higher screen-to-body ratio.

Figure 5 is a diagram illustrating the technical characteristics of the cathode for the technology under the camera screen. The figure shows that the thickness of the cathode is too thick or too thin, which has become a current technical difficulty.

FIG. 6 is an explanatory diagram of a solution of the technology under the camera screen. The figure shows that the display area of the camera area under the screen uses the quantum dot light-emitting technology solution, and the solution can be obtained with the OLED light-emitting technology of other display areas.

FIG. 7 is an explanatory diagram of the solution of the technology under the camera screen. The figure illustrates the technical scheme of using quantum dots to emit light in the display area of the camera area under the screen, which can obtain a thin cathode path in this area and achieve high transparency in this area.

FIG. 8 is an illustration of the realization of the effect of the display device using this solution. As illustrated in the figure, this solution achieves the ultimate in superior performance while taking into account all aspects of the needs.

FIG. 9 is a specific structural diagram of Embodiment 1 using this solution. In the figure, only the anode E and the display drive backplane F are the same in the display a area and the display b area (the same process). The requirements match the corresponding functional film layers.

FIG. 10 is a specific structural diagram of Embodiment 2 using this solution. The display a region is the same as the display b region electron transport layer B, hole transport layer D, anode E and display drive backplane F (same process), the light-emitting layer and cathode are separated respectively, due to the quantum dot device in the a region and the b region. The OLED device shows a slight difference in voltage drive, and the balance is compensated by the difference in the drive signal in the a region and the b region.

FIG. 11 is a specific structural diagram of Embodiment 3 using this solution. The display a region is the same as the display b region electron transport layer B, hole transport layer D, anode E and display drive backplane F (same process), the light-emitting layer and cathode are separated respectively, due to the quantum dot device in the a region and the b region. The OLED device of the OLED device shows a slight difference in voltage driving. Using the pre-experimental selection of the light-emitting layer material in the a region and the b region, the mass-produced light-emitting layer C1 and OLED organic light-emitting layer C2 materials with similar light and color properties are obtained.

Figure 12 shows other derivative structures that employ this solution, ie other embodiments. For example, the area of a and b regions is deformed, and the shape is deformed; or other structures are similar, but different structures are applied; or other application scenarios or forms based on the hybrid method of quantum dot light emission and OLED organic layer light emission.

Detailed ways

The technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

The OLED organic thin film and quantum dot film layer involved in the present invention can be constructed by vacuum evaporation, Ink jetPrinting, spin coating, etc., and the cathode is constructed by vacuum evaporation.

It should be noted here that the cathodes in the a area and the b area use their own processes to achieve different transmittances in the following ways:

1. The cathode of area a is thinner, and the cathode of b is thicker, each of which is vapor-deposited with its own shadow mask, but the materials are the same;

2. The cathode in area a is highly transparent, and the cathode in b is not highly transparent. They are vapor-deposited respectively, and the materials are different. The optimization depends on the transmittance dependence;

3. Areas a and b first use a shared shadow mask to evaporate a thin layer (the thickness of a), and then use a shadow mask for area b only to evaporate only area b, which is equivalent to area b. Secondary film formation.

The cathode involved in the present invention is a metal with low work function, such as Mg, Ag, and Al, or the above-mentioned multi-element composite metal.

The organic functional layer involved in the present invention is a high mobility organic small molecule (evaporation method) or a high mobility polymer molecule (printing or spin coating method).

The light-emitting layer involved in this aspect, wherein the quantum dots are between 2-20nm in diameter, and are composed of IV, II-VI, IV-VI or III-V elements, such as silicon quantum dots, germanium quantum dots, cadmium sulfide quantum dots , cadmium selenide quantum dots, cadmium telluride quantum dots, zinc selenide quantum dots, indium phosphide quantum dots, indium arsenide quantum dots, etc.; or perovskite quantum dots, etc.; the OLED organic light-emitting layer is a variety of organic Fluorescent and phosphorescent luminescent materials.

The anode involved in the present invention is ITO with high work function, or a metal/ITO composite structure, wherein the metal is Ag or Al.

Example 1

As shown in Figure 9, only the anode E and the display drive backplane F are the same in the display a area and the display b area (the same process), and the hole transport layer, the light emitting layer, the electron transport layer and the cathode above the anode are separated. The requirements of light color performance match the corresponding functional film layer, wherein the cathode A1 is an ultra-thin structure (transmittance greater than 70%), and the cathode A2 is a semi-transparent structure (transmittance between 35% and 55%).

The features of this scheme: the display backplane and driving scheme of area a and b are the same as the traditional ones, and the display panels with the same light and color performance are matched by the difference of their respective diode structures.

Example 2

As shown in Figure 10, the display a region is the same as the display b region electron transport layer B, hole transport layer D, anode E and display drive backplane F (the same process), the light emitting layer and the cathode are separated respectively. The quantum dot device and the OLED device in the b region show a slight difference in voltage driving. The difference in the driving signal in the a region and the b region is used to compensate the balance. This signal includes the power supply signal VDD, VEE, and also the data signal Vdata, etc.; the cathode A1 is the super Thin structure (transmittance greater than 70%), cathode A2 is semi-transparent structure (transmittance between 35% and 55%).

The characteristics of this scheme: the power drive backplane, anode and functional film layer of area a and area b are the same, only the light-emitting layer and cathode are different, and the process is relatively simple; the driving scheme needs signal compensation for different areas, and the overall effect of balanced light and color is achieved .

Example 3

As shown in Figure 11, the display a region is the same as the display b region electron transport layer B, hole transport layer D, anode E and display drive backplane F (same process), the light emitting layer and the cathode are separated respectively. The quantum dot device and the OLED device in the b region show a slight difference in voltage driving. Using the pre-experimental selection of the light-emitting layer material in the a region and the b region, the quantum dot light-emitting layer C1 and OLED organic light-emitting layer C2 materials with similar light and color properties are obtained. Functional layers B and D can also be selected through device pre-experiments; the cathode A1 is an ultra-thin structure (transmittance greater than 70%), and the cathode A2 is a semi-permeable structure (transmittance is between 35% and 55%).

The features of this scheme: the power-driven backplane, anode, and functional film layer in area a and area b are the same, only the light-emitting layer and cathode are different, and the process is relatively simple; for the light-emitting layers C1 and C2, a large number of device pre-experimental selection is required, and a large amount of preliminary work.

The derivative structures based on the ideas of the present invention, as shown in Figure 12, such as the area deformation of a and b regions, the deformation of the shape; or other structures are similar, but different structures are applied; or based on quantum dot luminescence and OLED organic Other application scenarios or forms of layer luminescence mixing.

Claims (8)

1. a display panel suitable for a camera under the screen, is characterized in that, the display panel comprises a drive backplane, an anode, a hole transport layer, a light-emitting layer, an electron transport layer and a cathode; the display panel is divided into a display a region and a display Area b; the cathode of area a is a high transmittance cathode, the light-emitting layer is a quantum dot light-emitting layer, an under-screen camera is set below area a; the cathode of area b is a low transmittance cathode, and the light-emitting layer is OLED organic light-emitting Floor. 2 . The display panel according to claim 1 , wherein the cathodes of the display area a and the display area b are made of the same material, and the cathode thickness of the display area a is smaller than the cathode thickness of the display area b. 3 . 3. The display panel according to claim 1, wherein the cathodes of the display a region and the display b region adopt different materials, and the transmittance of the cathode material of the display a region is greater than the transmittance of the cathode material of the display b region . 4. The display panel according to claim 1, wherein the transmittance of the high transmittance cathode in the display area a is greater than 70%, and the transmittance of the low transmittance cathode in the display b area is between 35% and 35%. between 55%. 5. The display panel according to claim 1, wherein the quantum dot diameter of the quantum dot light-emitting layer is 2-20 nm In between, it is composed of IV, II-VI, IV-VI or III-V elements; quantum dots are selected from silicon quantum dots, germanium quantum dots, cadmium sulfide quantum dots, cadmium selenide quantum dots, cadmium telluride quantum dots, selenium quantum dots Any of zinc hydride quantum dots, indium phosphide quantum dots, indium arsenide quantum dots or perovskite quantum dots. 6. The display panel according to claim 1, wherein the display a region and the display b region use the same driving backplane and anode, and the hole transport layer, the light emitting layer, the electron transport layer and the cathode are separated from each other, and the use of the respective The difference in diode structure matches the display panel with the same light and color performance. 7. The display panel according to claim 1, wherein the display a region and the display b region adopt the same driving backplane, anode, hole transport layer and electron transport layer, and the light emitting layer and the cathode are separated respectively, and the display The difference between the driving signals of the a region and the display region b is compensated for the balance, or a display panel with the same light and color properties can be matched by screening the light-emitting layer materials with similar light and color properties. 8 . The display panel according to claim 1 , wherein there are one or two display a-zones. 9 .

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