A quantum dot display panel and preparation method thereof

Abstract

The present invention relates to the technical field of display equipment, and provides a quantum dot display panel and a preparation method thereof, wherein the display panel comprises, from bottom to top, a substrate, a thin film transistor layer, a transparent anode layer, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer and a metal cathode layer; wherein, an encapsulation layer for wrapping the quantum dot light-emitting layer is prepared on the upper part of the quantum dot light-emitting layer, and the encapsulation layer comprises a barrier layer arranged on both sides of the quantum dot light-emitting layer, and PET substrate layers and optical structure layers are prepared on both sides of the barrier layer in sequence, and the optical structure layers can increase the blue light return path and uniformly emit light from the quantum dot light-emitting layer; the present invention proposes a new display panel using quantum dot material light-emitting technology to solve the problem of screen burn-in of OLED in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of display devices, and in particular to a quantum dot display panel and a preparation method thereof. Background Art

[0002] Currently in the mainstream TV market, there are three types of panels: QLED (LED with quantum dot technology), OLED and LED; among them, OLED stands for organic light-emitting diode, which is a self-luminous display. The OLED display panel includes a substrate layer, a thin-film transistor layer, an OLED light-emitting layer, a first inorganic encapsulation layer, an organic encapsulation layer, a second inorganic encapsulation layer, etc. from bottom to top. Among them, the organic encapsulation layer mainly plays the role of flattening and blocking the transmission of water and oxygen. Usually, the organic encapsulation layer is prepared by IJP (inkjet printing), that is, printing ink is dripped on the first inorganic encapsulation layer, and the ink is solidified after leveling to form the above-mentioned organic encapsulation layer.

[0003] QLED is more like OLED. It can also emit light like OLED, but the light source is not a diode, but quantum dots. Quantum dots are nanometer-sized spherical materials that cannot be seen by the naked eye and emit light under the action of voltage. Simply put, quantum dots are actually particles that can emit light and change color. Semiconductor quantum dots have excellent characteristics such as high light color purity, high light quantum efficiency, adjustable light color, and long service life.

[0004] However, QLED and OLED in the existing technology are both evolved versions of LED panels and are currently the best display panels, but both have their own advantages and disadvantages. QLED can provide better colors than ordinary LED panels, but it is not as good as OLED in terms of contrast and viewing angle, and OLED has the disadvantage of "screen burn-in"; among them, the phenomenon of "screen burn-in" is caused by long-term cathode ray tube. When the screen displays a static image for a long time, the image will leave a "residual image" on the screen. The real principle is that the phosphor behind the TV screen has been emitting light for too long without any "rest", resulting in phosphor loss and forming a fixed picture. For users who watch one or a type of video for a long time, it may affect the picture display effect when they watch. Summary of the invention

[0005] Technical issues solved

[0006] In view of the shortcomings of the prior art, the present invention provides a quantum dot display panel and a method for preparing the same, and proposes a new display panel using quantum dot material luminescence technology to solve the problem of OLED screen burn-in in the prior art.

[0007] Technical Solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] On one hand, the present invention provides a quantum dot display panel, which includes, from bottom to top, a base substrate, a thin film transistor layer, a transparent anode layer, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer and a metal cathode layer;

[0010] Among them, an encapsulation layer for wrapping the quantum dot light-emitting layer is prepared on the upper part of the quantum dot light-emitting layer, and the encapsulation layer includes a barrier layer placed on both sides of the quantum dot light-emitting layer, and a PET substrate layer and an optical structure layer are prepared in sequence on both sides of the barrier layer. The optical structure layer can increase the blue light return path and uniformly emit light from the quantum dot light-emitting layer.

[0011] Another aspect of the present invention provides a method for preparing a quantum dot display panel, comprising the following steps:

[0012] Providing a base substrate, and forming a pixel definition layer on the base substrate;

[0013] A plurality of hole injection layers are formed on the transparent anode layer respectively by using a solution film forming method;

[0014] Providing an electrochemically active material, mixing the electrochemically active material with a solvent, and coating the mixture on a plurality of hole injection layers to form a plurality of polymer films, wherein the polymer films are hole transport layers;

[0015] A quantum dot film is prepared by a slit coating process, wherein the quantum dot film is an electron transport layer;

[0016] A thin film transistor layer, a transparent anode layer, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer and a metal cathode layer are sequentially manufactured on the base substrate to complete the manufacture of the quantum dot display panel.

[0017] Preferably, the base substrate is a glass substrate or a flexible transparent substrate, the glass substrate uses sapphire, quartz or glass material as a substrate, and the flexible transparent substrate is a colorless, highly transparent polyimide film with a transmittance greater than 90% in the visible light region.

[0018] Preferably, the quantum dot light-emitting layer mainly includes quantum dots and a carrier layer of quantum dots, and the carrier layer is one of silica gel, PMMA, PC, PVA, EVA, epoxy resin, polyurethane, photoresist or PVP material.

[0019] Preferably, the quantum dots are InP / ZnSe / ZnS core-shell fluorescent quantum dots, hydrofluoric acid is added during the initial growth of the ZnSe shell to etch away the oxidized InP core surface, and then high-temperature ZnSe growth is achieved at 340°C.

[0020] Preferably, the steps of preparing the quantum dot film by the slit coating process are: making an optical micro-nano structure on the surface of one side of the PET substrate; making a barrier layer on the surface of the other side of the PET substrate; coating a polymer glue with quantum dot material between the barrier layers; and forming a multi-layer composite structure through a thermal curing or photocuring process, namely, a quantum dot light-emitting layer.

[0021] Beneficial Effects

[0022] The present invention provides a quantum dot display panel and a method for preparing the same. Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention proposes a QD-OLED display panel by adopting the technology of combining OLED display and quantum dots. The packaged organic light-emitting material in the OLED functional layer is replaced by quantum dot light-emitting diodes, while retaining good contrast and viewing angle. Since quantum dot technology is used in the light-emitting material, its color effect is even stronger than that of a true OLED, and the burn-in problem will be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a schematic diagram of the structure of the quantum dot display panel of the present invention;

[0026] Figure 2 It is a schematic diagram of the quantum dot light-emitting layer and its encapsulation layer of the present invention;

[0027] Figure 3 This is a flow chart of the method for preparing a quantum dot display panel of the present invention;

[0028] The numbers in the figure represent: 1-substrate; 2-thin film transistor layer; 3-transparent anode layer; 4-hole injection layer; 5-hole transport layer; 6-quantum dot light-emitting layer; 7-electron transport layer; 8-metal cathode layer; 9-encapsulation layer; 91-barrier layer; 92-PET substrate layer; 93-optical structure layer; 94-quantum dots; 95-carrier layer. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example:

[0031] In one aspect, the present invention provides a quantum dot display panel, referring to Figure 1-2 The display panel includes, from bottom to top, a base substrate 1, a thin film transistor layer 2, a transparent anode layer 3, a hole injection layer 4, a hole transport layer 5, a quantum dot light-emitting layer 6, an electron transport layer 7 and a metal cathode layer 8;

[0032] Among them, an encapsulation layer 9 for wrapping the quantum dot light-emitting layer 6 is prepared on the upper part of the quantum dot light-emitting layer 6, and the encapsulation layer 9 includes a barrier layer 91 placed on both sides of the quantum dot light-emitting layer 6, and a PET substrate layer 92 and an optical structure layer 93 are prepared in sequence on both sides of the barrier layer 91. The optical structure layer 93 can increase the blue light return path and uniformly emit light from the quantum dot light-emitting layer 6.

[0033] Specifically, the substrate 1 is a glass substrate or a flexible transparent substrate. The glass substrate uses sapphire, quartz or glass as a substrate. The flexible transparent substrate is a colorless, highly transparent polyimide film with a transmittance greater than 90% in the visible light region. The preparation of the polyimide film is to prepare a series of semi-aromatic polyimides by synthesizing a variety of new fluorine-containing and sulfone-containing aromatic diamine monomers and alicyclic dianhydrides with different structures. In this embodiment, a sapphire substrate is preferably used.

[0034] Specifically, the quantum dot light-emitting layer 6 mainly includes quantum dots 94 and a carrier layer 95 of the quantum dots 94, and the carrier layer 95 is a material of silica gel, PMMA, PC, PVA, EVA, epoxy resin, polyurethane, photoresist or PVP. In this embodiment, the barrier layer 91 preferably adopts an oxygen-isolating and water-blocking SiO2 coating, and the optical micro-nano structure is a hemispherical or conical microstructure uniformly arrayed on the surface of the PET substrate. The carrier layer can achieve full mixing with the quantum dot 94 material, which plays a first water-and-oxygen-blocking and protective effect, and the oxygen-and-water-blocking SiO2 coating is used to achieve a second water-and-oxygen-blocking and protective effect on the quantum dot light-emitting layer 6. Among them, by setting the optical micro-nano structure, it has the effect of increasing the blue light return path and averaging the light. It uses the array distribution of the preferred hemispherical micro-protrusions. Through the transmittance simulation experimental data, it is known that it can effectively improve the projection of light, thereby greatly improving the incremental effect of the quantum dot light-emitting layer 6.

[0035] Among them, the quantum dots 94 in this embodiment use InP / ZnSe / ZnS core-shell fluorescent quantum dots 94, hydrofluoric acid is added during the growth of the initial ZnSe shell to etch off the oxidized InP core surface, and then the growth of high-temperature ZnSe is achieved at 340°C; the engineered shell thickness can inhibit energy transfer and Auger recombination to maintain high luminous efficiency, and the initial surface ligands are replaced by shorter ligands to achieve better charge injection. In this embodiment, the use of InP / ZnSe / ZnS core-shell fluorescent quantum dots 94 avoids the use of toxic and harmful substances such as cadmium in electronic products, and makes a cadmium-free quantum dot film.

[0036] Specifically, the material of the electron transport layer 7 in this embodiment is one or more of ZnO, TiO2, SnO, ZrO2, Ta2O3, AlZnO, ZnSnO and InSnO.

[0037] The material of the hole transport layer 5 is one or more of NPB, TPD, TAPC and p-TPD. Specifically, it is an organic material with hole transport capability, which can be but not limited to N, N'-diphenyl-N, N'-(1-naphthyl)-1, 1'-biphenyl-4, 4'-diamine (NPB); N, N'-diphenyl-N, N'-di(3-methylphenyl)-1, 1'-biphenyl-4, 4'-diamine (TPD), poly(N, N'-bis(4-butylphenyl)-N, N'-bis(phenyl)benzidine) (poly-TPD); 4, 4'-cyclohexylbis[N, N-bis(4-methylphenyl)aniline (TAPC) or a mixture thereof.

[0038] Specifically, the material of the hole injection layer in this embodiment is one or more of PEDOT:PSS, CuPc, F4-TCNQ, HATCN, molybdenum oxide, vanadium oxide, tungsten oxide, chromium oxide, MoS2, WS2, MoSe2, and WSe2; the material of the transparent anode layer 3 is ITO, IZO, graphene or a conductive polymer.

[0039] Among them, the display panel realizes the light-emitting method of the electroluminescent mechanism by placing the quantum dot light-emitting layer 6 based on the quantum dot 94 material between the anode layer and the cathode layer. Based on the quantum dot 94 in each pixel, it is emitted by the current, and each sub-pixel contains red, green and blue QD. Because each pixel can be controlled independently, the display panel has a high contrast, and at the same time, it does not require backlight and color filter, and the power consumption is low. Quantum dot 94 technology is used in the light-emitting material, so its effect in the color part is even stronger than the real OLED, and there is no organic material, which avoids the occurrence of burn-in problems.

[0040] Another aspect of the present invention provides a method for preparing a quantum dot 94 display panel, referring to Figure 3; comprising the following steps:

[0041] Step 1: providing a base substrate 1, and forming a pixel definition layer on the base substrate 1;

[0042] Step 2: forming a plurality of hole injection layers 4 on the transparent anode layer 3 by using a solution film forming method;

[0043] Step 3: providing an electrochemically active material, mixing the electrochemically active material with a solvent, and coating the mixture on a plurality of hole injection layers 4 to form a plurality of polymer films, which are the hole transport layers 5;

[0044] Step 4: preparing a quantum dot film by a slit coating process, the quantum dot film being the electron transport layer 7;

[0045] Step 5: On the base substrate 1, a thin film transistor layer 2, a transparent anode layer 3, a hole injection layer 4, a hole transport layer 5, a quantum dot light-emitting layer 6, an electron transport layer 7 and a metal cathode layer 8 are sequentially produced to complete the production of the quantum dot 94 display panel.

[0046] In step 4, the quantum dot film is prepared by the slot coating process. The operating principle is to pump a certain amount of fluid into a mold that can evenly spread the fluid. It is a closed system, and secondly, it pre-meters the coating material through a precision metering pump. It is based on these two points that the slot coating method has some advantages that other coating methods do not have: more uniform coating weight and overall distribution; easy to switch between thick and thin coating processes; minimize volatile emissions, coating contamination, and raw material waste.

[0047] Specifically, the steps for preparing the quantum dot film by the slit coating process are as follows: making an optical micro-nano structure on one surface of the PET substrate; making a barrier layer 91 on the other surface of the PET substrate; coating a polymer glue having quantum dot 94 material between the barrier layers 91; and forming a multi-layer composite structure, namely the quantum dot light-emitting layer 6, by thermal curing or photocuring process.

[0048] The present invention proposes a QD-OLED display panel by adopting the technology of combining OLED display and quantum dot 94. The packaged machine-made luminescent material is replaced with quantum dot 94 light-emitting diodes in the OLED functional layer, while retaining good contrast and viewing angle. Since quantum dot 94 technology is used in the luminescent material, its color effect is even stronger than that of a true OLED, and the burn-in problem will be avoided.

[0049] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A quantum dot display panel, characterized in that: The display panel includes, from bottom to top, a substrate, a thin film transistor layer, a transparent anode layer, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer and a metal cathode layer; Among them, an encapsulation layer for wrapping the quantum dot light-emitting layer is prepared on the upper part of the quantum dot light-emitting layer, and the encapsulation layer includes a barrier layer placed on both sides of the quantum dot light-emitting layer, and a PET substrate layer and an optical structure layer are sequentially prepared on both sides of the barrier layer, and the optical structure layer can increase the blue light return path and uniformly emit light from the quantum dot light-emitting layer; The quantum dot light-emitting layer mainly includes quantum dots and a carrier layer of quantum dots, and the carrier layer is one of silica gel, PMMA, PC, PVA, EVA, epoxy resin, polyurethane, photoresist or PVP material.

2. A quantum dot display panel according to claim 1, characterized in that: The substrate is a glass substrate or a flexible transparent substrate. The glass substrate uses sapphire, quartz or glass as a substrate. The flexible transparent substrate is a colorless, highly transparent polyimide film with a transmittance greater than 90% in the visible light region.

3. A quantum dot display panel according to claim 1, characterized in that: The quantum dots are InP / ZnSe / ZnS core-shell fluorescent quantum dots. Hydrofluoric acid is added during the initial growth of the ZnSe shell to etch away the oxidized InP core surface, and then high-temperature ZnSe growth is achieved at 340°C.

4. The quantum dot display panel according to claim 1, characterized in that: The material of the electron transport layer is one or more of ZnO, TiO2, SnO, ZrO2, Ta2O3, AlZnO, ZnSnO and InSnO.

5. The quantum dot display panel according to claim 1, characterized in that: The material of the hole transport layer is one or more of NPB, TPD, TAPC and p-TPD.

6. The quantum dot display panel according to claim 1, characterized in that: The material of the hole injection layer is one or more of PEDOT:PSS, CuPc, F4-TCNQ, HATCN, molybdenum oxide, vanadium oxide, tungsten oxide, chromium oxide, MoS2, WS2, MoSe2, and WSe2; the material of the transparent anode layer is ITO, IZO, graphene, or a conductive polymer.

7. A method for preparing the quantum dot display panel as claimed in claim 1, characterized in that: The steps include: Providing a base substrate, and forming a pixel definition layer on the base substrate; A plurality of hole injection layers are formed on the transparent anode layer respectively by using a solution film forming method; Providing an electrochemically active material, mixing the electrochemically active material with a solvent, and coating the mixture on a plurality of hole injection layers to form a plurality of polymer films, which are hole transport layers; preparing a quantum dot film by a slit coating process, which is an electron transport layer; A thin film transistor layer, a transparent anode layer, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer and a metal cathode layer are sequentially manufactured on the base substrate to complete the manufacture of the quantum dot display panel.

8. The method according to claim 7, characterized in that: The steps of preparing the quantum dot film by the slit coating process are: making an optical micro-nano structure on one surface of the PET substrate; Making a barrier layer on the other side of the PET substrate; Coating a polymer glue having a quantum dot material between the barrier layers; Through thermal curing or photocuring process, a multi-layer composite structure is formed, which is the quantum dot light-emitting layer.

9. The method according to claim 8, characterized in that: The barrier layer is an oxygen-isolating and water-blocking SiO2 coating, and the optical micro-nano structure is a hemispherical or conical microstructure uniformly arrayed on the surface of the PET substrate.

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