Display panel and display device

Abstract

The present application discloses a display panel and a display device, including a substrate and a backplane layer arranged on the substrate, an anode layer is arranged on the backplane layer, a red and green quantum dot light-emitting layer is arranged on the anode layer, a blue light-emitting layer is arranged on the red and green quantum dot light-emitting layer, and a first connection layer and a second connection layer are arranged between the red and green quantum dot light-emitting layer and the blue light-emitting layer; the first connection layer is close to the red and green quantum dot light-emitting layer, and the first connection layer is an N-type semiconductor layer; the second connection layer is close to the blue light-emitting layer, and the second connection layer is a P-type semiconductor layer. According to the technical solution of the present application, by using quantum dots to prepare the red and green light-emitting layers, the color purity of the light emitted by the display panel is effectively improved, and at the same time, the red and green light-emitting layers and the blue light-emitting layers are connected in series, and the red and green quantum dots are combined with the blue organic fluorescent material, so as to balance the light-emitting life of the three colors of red, green and blue, and at the same time, the light-emitting layers in series have higher light-emitting efficiency and service life.

Description

Technical Field

[0001] The present invention generally relates to the field of display, and more particularly to a display panel and a display device. Background Art

[0002] Active matrix organic light emitting diode (AMOLED) has gradually replaced LCD liquid crystal display technology with its advantages such as ultra-thin, flexible, and low driving voltage. With the continuous development of technology, flexible display products have gradually become the mainstream of the market, and foldable products have put forward higher requirements on the thickness of display products. In the display module, the thickest material is the polarizer (POL), with a minimum thickness of 45 microns, which will seriously affect the bending radius of the AMOLED display; and the maximum light transmittance of the polarizer is only 50%, which will seriously affect the external quantum efficiency of the light-emitting device and increase the power consumption of the display device. Based on the above analysis, the development of a new generation of core display materials and devices is particularly critical. Summary of the invention

[0003] In view of the above defects or shortcomings in the prior art, it is desirable to provide a display panel and a display device.

[0004] In a first aspect, a display panel is provided, comprising a base substrate and a backplane layer arranged on the base substrate, wherein an anode layer is arranged on the backplane layer, a red and green quantum dot light-emitting layer is arranged on the anode layer, and a blue light-emitting layer is arranged on the side of the red and green quantum dot light-emitting layer away from the anode layer.

[0005] According to the technical solution provided in the embodiments of the present application, by using quantum dots to prepare red and green light-emitting layers, the color purity of the light emitted by the display panel is effectively improved, and the red and green quantum dots are combined with blue organic fluorescent materials to balance the light emission life of the three colors of red, green and blue. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0007] Figure 1 FIG. 1 is a schematic diagram of the structure of the display panel in this embodiment. DETAILED DESCRIPTION

[0008] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0009] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0010] Please refer to Figure 1 This embodiment provides a display panel, including a base substrate 1 and a backplane layer 2 arranged on the base substrate 1, the backplane layer 2 is provided with an anode layer 3, the anode layer 3 is provided with a red and green quantum dot light-emitting layer 4, and the red and green quantum dot light-emitting layer 4 is provided with a blue light-emitting layer 11 on the side away from the anode layer.

[0011] This embodiment uses quantum dots to prepare red and green light-emitting layers, which effectively improves the color purity of the light emitted by the display panel. The blue light-emitting layer is also prepared using organic fluorescent materials in the prior art, which balances the light-emitting lifespan of the three colors of red, green and blue.

[0012] Furthermore, a first connection layer 8 and a second connection layer 9 are provided between the red and green quantum dot light-emitting layer 4 and the blue light-emitting layer 11;

[0013] The first connection layer 8 is close to the red and green quantum dot light-emitting layer 4. The first connection layer 8 is an N-type semiconductor layer. A first electron transport layer 7 is further provided between the red and green quantum dot light-emitting layer 4 and the first connection layer 8.

[0014] The second connection layer 9 is located near the blue light-emitting layer 11 . The second connection layer 9 is a P-type semiconductor layer. A first hole transport layer 10 is disposed between the second connection layer 9 and the blue light-emitting layer 11 .

[0015] In this embodiment, the red and green light-emitting layers and the blue light-emitting layer are connected in series to form a series structure, and the red and green quantum dots and the blue organic fluorescent material are combined to balance the luminescence life of the three colors of red, green and blue. At the same time, the series-connected light-emitting layers have higher luminescence efficiency and service life.

[0016] Preferably, the materials for preparing the red and green quantum dot light-emitting layer 4 are red perovskite quantum dots, green perovskite quantum dots and an organic solvent.

[0017] In this embodiment, perovskite quantum dot materials are used to prepare red and green light-emitting layers. First, red and green perovskite quantum dot materials are synthesized. The synthesis can be performed by hot injection method, ligand-assisted reprecipitation method, one-pot method, aqueous phase method, solution gel method, microemulsion method, microwave-assisted method, and the perovskite quantum dot material is further dispersed and dissolved in an organic solvent, wherein the organic solvent is one of chlorobenzene, dichlorobenzene, toluene, silane, chloroform, tetrahydrofuran, acetone and the like, or a mixture of multiple solvents. The perovskite quantum dot solution is further prepared into a light-emitting film by spin coating, inkjet printing or doctoring. The thickness of the red and green quantum dot light-emitting layer is 20-100 nanometers. The red quantum dots and green quantum dots are added to the organic solvent in a certain ratio, and the specific addition ratio is adjusted according to the actual situation.

[0018] The red and green light-emitting layers are prepared by using perovskite quantum dots, wherein the perovskite quantum dot material is an ABX3 structure, or (A1)2(A2) n-1 Pb n X 3n+1 Structure. A, A1 and A2 are all cations, B is a metal ion, X is a halogen ion, and the specific position of A can be an inorganic ion Na + , K + , Ca + , Cs + , or a short-chain organic cation CH3NH3 + (abbreviated as MA), NH2CH=NH2 + (FA for short) or long-chain organic cation C6H5CH2CH2NH3 + (PEA for short + )、C6H5CH2NH3 + (PMA + )、CH3CH2CH2CH2NH3 + (referred to as BA+), C(CH3)3NH3 + (abbreviated as t-BA + )、CH3CH2CH2NH3 + (abbreviated as PA + ), C 11 H 12 N + (referred to as 1-Naphthylmethylmethylammonium + ,NMA+)、CH(CH3)2CH2NH3 + (referred to as i-BA +), the A position can also be a mixture of inorganic cations and organic cations, or a mixture of multiple inorganic cations, or a mixture of multiple organic cations; the B position is Bi 3+ Sn 2+ , Pb 2+ , Mn, Co, Fe elements, the B position can also be a mixture of multiple elements; the X position is O 2- ,I - Br - , Cl - Elements, X position is a halogen ion, which can include I - Br - , Cl - etc., or a mixture of multiple elements; the molecular formula of green perovskite quantum dots can be: FAPbBr3 or CsPbBr3 or PEA2FA2Pb3Br 10 or PEA2PbBr4 or PEA2FA 1.8 Cs 0.2 Pb3Br9Cl; the molecular formula of red perovskite quantum dots can be: FAPbI3, CsPbI3, (PEA)2FA2Pb3I 10 ,(PEA)2PbI4,(PEA)2FA 1.8 Cs 0.2 Pb3I9Cl.

[0019] Preferably, the blue light-emitting layer material is an organic small molecule fluorescent material. Since the luminous efficiency of blue quantum dots is lower than that of red and green quantum dots, the blue organic small molecule fluorescent material is still used in the present embodiment to ensure the luminous efficiency and color purity of the entire display panel. The blue light-emitting layer is prepared by vacuum thermal evaporation, and the thickness of the blue light-emitting layer is 20-50 nanometers.

[0020] In this embodiment, a first electron transport layer, two doping layers and a first hole transport layer are sequentially arranged between the red and green quantum dot light-emitting layers and the blue light-emitting layer. The red and green quantum dot light-emitting layers and the blue light-emitting layer are connected in series through the above layer structure. In addition, when preparing the red and green light-emitting layers and the blue light-emitting layers, no metal mask plate is required. The setting of the light-emitting layer structure is simpler, which reduces the production cost and shortens the production time. Among them, the first electron transport layer material is zinc oxide (ZnO), zinc magnesium oxide (ZnMgO), titanium oxide (TiO2), tin oxide (SnO2 ), or OXD7 and other organic polymer materials, when the above materials are used, the first electron transport layer thin film is prepared by spin coating, inkjet printing, or blade coating. The first electron transport layer can also be an organic small molecule material, such as TPBi (C45H30N6, 2,2',2"-(1,3,5-benzinetriyl)-tris (1-phenyl-1-Hbenzimidazole), Bphen (C24H16N2, 4,7-diphenyl-1,10-phenanthrol ine), C60 (Fullerene-C60), Liq (C9H6LiNO, 8-hydroxyquinolinolato-lithium), BAlp (C32H25AlN2O3, Bis(2 -methyl-8-quinolinolate)-4-(phenylphenolato)aluminium), BCP(C26H20N2, 2,9-dimethyl-4,7-diphenyl-1, 10-phenanthroline), Alq3(C27H18AlN3O3, Tris(8-hydroxy-quinolinato)aluminium), B3PyPB, B3PyPPM, TmPyP B(C39H27N3, 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene), TpPyPB, CuPc(C32H16N8Cu, Phthalocyanine, copper The first electron transport layer can be prepared by vacuum thermal evaporation of the above small molecule materials, wherein the thickness of the prepared first electron transport layer is 20-100 nanometers.

[0021] Furthermore, the first connection layer 8 is an N-type doped layer, the doping type is a host-guest doping type, the host material is any one of the following: zinc oxide, magnesium zinc oxide, titanium oxide, tin oxide, or OXD7, and the guest material is a metal or a metal compound.

[0022] A first connecting layer is arranged on the side of the first electron transport layer away from the red and green quantum dot light-emitting layers, and the first connecting layer is an N-type semiconductor layer. The N-type semiconductor structure is of a host-guest doped type, and the host material is the same as the material of the first electron transport layer, which is zinc oxide (ZnO), zinc magnesium oxide (ZnMgO), titanium oxide (TiO2), tin oxide (SnO2), or organic polymer materials such as OXD7, and the metal of the guest material is Li, Na, K, Rb, Cs, Mg, Yb, Ca, Re and other metals or corresponding metal compounds; the first connecting layer is prepared by vacuum thermal evaporation, wherein a dual-source co-evaporation method is adopted, and the thickness of the prepared first connecting layer is 10-30 nanometers.

[0023] Further, the second connecting layer 9 is a P-type doped layer, the doping type is a host-guest doping type, the host material is any one of the following: NPB (C44H32N2), TPD, TAPC (bis (di-p-toluidine) phenylcyclohexane), TCTA, CBP, MCP (methylcyclopentenolone), the above materials are all hole transport materials, the guest material is a metal compound material or an organic material, the metal compound material is any one of the following: MoO x , SbCl5, FeCl3, the organic material is any one of the following: F4-TCNQ, HAT-CN, pentacene.

[0024] Furthermore, the material of the second connection layer 9 is any one of the following: NPB, TPD, TAPC, TCTA, CBP, MCP.

[0025] A second connection layer is arranged on the side of the first connection layer away from the first electron transport layer, and the second connection layer is a P-type semiconductor layer. The P-type semiconductor structure can be a non-doped structure or a host-guest doped structure. When the second connection layer is a non-doped structure, the material used is the same as the material of the first hole transport layer, which is an organic small molecule hole transport layer material such as NPB, TPD, TAPC, TCTA, CBP, MCP, etc.; when the second connection layer is a doped structure, its main material is the same as the second hole transport layer, which is an organic small molecule hole transport layer material such as NPB, TPD, TAPC, TCTA, CBP, MCP, etc., and the guest material is a metal compound or an organic material, the metal compound can be MoOx, SbCl5, FeCl3, etc., and the organic material can be F4-TCNQ or HAT-CN, pentacene, etc.; the preparation method of the second connection layer is the same as the preparation method of the first connection layer, and is prepared by vacuum thermal evaporation, wherein a dual-source co-evaporation method is adopted, and the thickness of the prepared second connection layer is 10-30 nanometers.

[0026] Finally, a first hole transport layer is formed between the second connecting layer and the blue light-emitting layer. The material of the first hole transport layer is an organic small molecule hole transport layer material such as NPB, TPD, TAPC, TCTA, CBP, MCP, etc. It can be prepared by vacuum thermal evaporation. The thickness of the prepared first hole transport layer is 10-30 nanometers.

[0027] Furthermore, a hole injection layer 4 is provided on a side of the anode layer 3 away from the back plate layer 2, and a second hole transport layer 5 is provided on a side of the hole injection layer 4 away from the anode layer 3;

[0028] A second electron transport layer 12 is disposed on a side of the blue light-emitting layer 11 away from the first hole transport layer 10 , and a cathode layer 13 is disposed on a side of the second electron transport layer 12 away from the blue light-emitting layer 11 .

[0029] This embodiment also provides the structure of other parts of the display panel, forming a hole injection layer and a second hole transport layer on the anode layer, and forming a second electron transport layer and a cathode layer on the blue light-emitting layer;

[0030] The hole injection layer material disposed on the anode layer is polyethylene dioxythiophene-poly (styrene sulfonate), and the hole injection layer is prepared by a one-step spin coating method, an inkjet printing method, or a blade coating method, and the hole injection layer has a thickness of 5-30 nanometers;

[0031] The second hole transport layer material disposed on the hole injection layer is a polymer organic material or a small molecule organic material such as poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(4,4′-(N-(4-n-butyl)phenyl)-diphenylamine)], poly(9-vinylcarbazole), poly[N,N′-bis(4-butylphenyl)-N,N′-bisphenylbenzidine], or a mixture of multiple materials. The second hole transport layer film is prepared by a one-step spin coating method, an inkjet printing method, or a doctor blade coating method, and the film thickness is 20-100 nanometers.

[0032] The second electron transport layer material arranged on the blue light-emitting layer is an organic small molecule material, such as TPBi, Bphen, C60, Liq, BAlp, BCP, Alq3, B3PyPB, B3PyPPM, TmPyPB, TpPyPB, CuPc, etc., or a mixture of the above materials. The second electron transport layer film is prepared by a vacuum thermal evaporation method, and the film thickness is 20-50 nanometers.

[0033] Furthermore, the cathode layer 13 is a transparent electrode layer, and the cathode layer material is ITO or IZO. In this embodiment, a transparent electrode is used to prepare the cathode layer. The conventional cathode layer is made of metal, and the metal surface has strong reflection. The transparent cathode can reduce the light reflection on the surface of the display panel, further improving the low contrast problem caused by light reflection; further, there is no need to use a polarizer, so that the prepared display panel has a thinner thickness, improves the efficiency of the light emitting quantum, and can be more conducive to the flexible screen to realize the folding display technology.

[0034] Furthermore, a packaging layer 14 is disposed on the cathode layer 13 , a color filter layer 15 is disposed on a side of the packaging layer 14 away from the cathode layer 13 , and a cover layer 16 is disposed on the color filter layer 15 .

[0035] In this embodiment, an encapsulation layer is formed on the cathode layer, a color filter layer is arranged on the encapsulation layer, light passes through the color filter layer to form output light of different colors, a cover layer is formed on the color filter layer, the cover layer is a transparent PI material or ultra-thin glass, etc., and unnecessary luminous spectrum is further filtered and external light reflection is prevented through the encapsulation layer and the color filter layer.

[0036] In this embodiment, perovskite quantum dots are used to prepare red and green quantum dot light-emitting layers, and the red and green quantum dot light-emitting layers and the blue light-emitting layer form a tandem device structure to form a white tandem electroluminescent device. White light passes through the color film layer to form light of different colors, which balances the service life of the three light-emitting layers while ensuring the color purity of the light emitted by the display device. Furthermore, since perovskite quantum dots are used as light-emitting materials, the half-width of the light-emitting spectrum of the perovskite quantum dots is about 20 nanometers, and therefore the microcavity structure of the display device can be omitted, and a transparent electrode is used as the cathode layer to reduce the reflectivity of the display panel and improve the contrast.

[0037] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A display panel, comprising a base substrate and a backplane layer arranged on the base substrate, characterized in that: The backplane layer is provided with an anode layer, the anode layer is provided with a red and green quantum dot light-emitting layer, the side of the red and green quantum dot light-emitting layer away from the anode layer is provided with a blue light-emitting layer, the side of the anode layer away from the backplane layer is provided with a hole injection layer, and the side of the hole injection layer away from the anode layer is provided with a second hole transport layer; The blue light-emitting layer is prepared by using a blue organic small molecule fluorescent material through vacuum thermal evaporation; A first connecting layer and a second connecting layer are provided between the red and green quantum dot light-emitting layer and the blue light-emitting layer; The first connection layer is close to the red and green quantum dot light-emitting layer, the first connection layer is an N-type semiconductor layer, and a first electron transport layer is further provided between the red and green quantum dot light-emitting layer and the first connection layer; The second connection layer is close to the blue light-emitting layer, the second connection layer is a P-type semiconductor layer, a first hole transport layer is provided between the second connection layer and the blue light-emitting layer, and the red and green quantum dot light-emitting layers and the blue light-emitting layer are connected in series through the first electron transport layer, the first connection layer, the second connection layer and the first hole transport layer; A second electron transport layer is provided on the side of the blue light-emitting layer away from the first hole transport layer, and a cathode layer is provided on the side of the second electron transport layer away from the blue light-emitting layer, wherein the cathode layer is a transparent electrode layer; The preparation process of the red and green quantum dot light-emitting layer includes: Synthesize red and green perovskite quantum dot materials; Adding the red and green perovskite quantum dot materials into an organic solvent according to a preset ratio to obtain a perovskite quantum dot solution; The perovskite quantum dot solution is prepared into a light-emitting film by spin coating, inkjet printing or blade coating to obtain the red and green quantum dot light-emitting layer.

2. The display panel according to claim 1, characterized in that: The cathode layer material is ITO or IZO.

3. The display panel according to claim 1, characterized in that: A packaging layer is arranged on the cathode layer, a color filter layer is arranged on a side of the packaging layer away from the cathode layer, and a cover layer is arranged on the color filter layer.

4. The display panel according to any one of claims 1 to 3, characterized in that: The first connection layer is an N-type doped layer, the doping type is a host-guest doping type, the host material is any one of the following: zinc oxide, magnesium zinc oxide, titanium oxide, tin oxide, or OXD7, and the guest material is a metal or a metal compound.

5. The display panel according to any one of claims 1 to 3, characterized in that: The second connecting layer is a P-type doped layer, and the doping type is a host-guest doping type. The host material is any one of the following: NPB, TPD, TAPC, TCTA, CBP, MCP, and the guest material is a metal compound material or an organic material. The metal compound material is any one of the following: MoOx, SbCl5, FeCl3, and the organic material is any one of the following: F4-TCNQ, HAT-CN, pentacene.

6. The display panel according to any one of claims 1 to 3, characterized in that: The second connection layer material is any one of the following: NPB, TPD, TAPC, TCTA, CBP, MCP.

7. A display device, characterized in that: A display panel comprising any one of claims 1-6.

Images