Carbon nanotube composite charge generation layer and preparation method thereof, and laminated OLED device

Abstract

The application provides a carbon nanotube composite charge generation layer, a preparation method thereof and application of the carbon nanotube composite charge generation layer in a laminated OLED device. The preparation method comprises the following steps: placing a ferrous oxide loaded carbon nanotube composite material in a solvent to obtain a solution, spraying the solution on a substrate surface, drying to obtain a modified base film; placing the modified base film in a magnetic field with a fixed direction and a fixed frequency to obtain a modified base film with oriented arrangement of carbon nanotubes; and preparing the carbon nanotube composite charge generation layer by using a high-vacuum evaporation method. Compared with the prior art, the carbon nanotube material with regular arrangement is obtained, the axial conductivity of the carbon nanotube material is far higher than the radial conductivity, the traditional evaporation process is used, the CGL is prepared on the carbon nanotube layer with regular arrangement by the thermal evaporation method, and therefore the electrical crosstalk (lateral conductivity) of the CGL is reduced, and the performance of the laminated OLED device is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of display, and particularly relates to a carbon nanotube composite charge generation layer, a preparation method thereof and application thereof in a stacked OLED device. BACKGROUND

[0002] Organic light-emitting diode (OLED) display is generally regarded as one of the most promising lighting and display devices due to its low cost, low power consumption, fast response speed, wide viewing angle, high contrast ratio, high brightness and other advantages. With the progress and development of science and technology, people have higher demands on the experience of display effect. In addition, the physical method path of wearing supporting display devices is feasible, and the arrival of the 5G era will solve the problem of data transmission. Therefore, in recent years, Micro OLED (Organic Light Emitting Display) is known as the dark horse of the next generation of display technology, and has been widely used in military markets such as wearable helmets, gun sights, night vision devices, etc. With the application of new technologies such as AR / VR and autonomous driving, Micro OLED micro display will experience explosive growth. The market has higher brightness and higher efficiency requirements for OLED devices.

[0003] In order to improve the light-emitting efficiency of OLED devices, stacked OLED devices gradually replace traditional single-layer OLED devices. By stacking light-emitting units, the stacked OLED device can not only effectively improve the brightness and light-emitting efficiency, but also realize high brightness under low current density, thereby avoiding leakage current and electric field breakdown, and further prolonging the service life of OLED. In the stacked OLED device, multiple light-emitting units are connected in series through a charge connection layer (also known as a charge generation layer, referred to as CGL), so that all light-emitting units can be driven under the same current density, thereby greatly improving the brightness of the stacked OLED device. The charge connection layer is a key component of the stacked OLED device, which needs to provide electrons and holes to adjacent light-emitting units at the same time, so most of the existing charge generation layers use metal / organic materials. Since there is metal in the charge generation layer, when the current passes through, due to the conductivity of the metal, the current will have lateral conduction, crosstalk will occur, and pixels that should not emit light will emit light, thereby reducing the display effect (see Figure 1 ).

[0004] In the prior art, patent CN 111599936 A, published on August 28, 2020, entitled "An Organic Light Emitting Display Panel and its Fabrication Method," discloses an array substrate comprising a first electrode layer, a pixel defining layer, and a second electrode layer, with a first opening structure in the pixel defining layer exposing a portion of the first electrode; a color filter substrate comprising: a conductive connection structure, a color resist layer, an elastic conductive wall, and a metal connecting pad; the conductive connection structure is located on the side of the second substrate facing the array substrate; the color resist layer is located on the side of the second substrate facing the array substrate; the gap between adjacent sub-pixel color resists exposes a portion of the conductive connection structure; the elastic conductive wall is located on the side of the conductive connection structure facing the array substrate; the elastic conductive wall contacts the conductive connection structure through the gap between adjacent sub-pixel color resists; the elastic conductive wall comprises an organic material matrix and conductive doped particles; the conductive doped particles include carbon nanoparticles, carbon nanotubes, graphene particles, silicon nanoparticles, or metal nanoparticles. Metal bonding pads are located on the surface of the elastic conductive wall facing the array substrate. The vertical projection of the elastic conductive wall onto the first substrate overlaps with the vertical projection of the pixel defining layer onto the first substrate, improving the electrical contact between the elastic conductive wall and the second electrode layer, as well as the light emission uniformity of the display panel. By directly incorporating a high proportion of carbon nanoparticles, carbon nanotubes, graphene particles, silicon nanoparticles, or metal nanoparticles into the organic material matrix of the elastic conductive wall, the conductivity of the elastic conductive wall 24 is improved. Furthermore, the doped conductive particles can reduce the light transmittance of the elastic conductive wall, preventing light emission crosstalk problems in adjacent sub-pixel regions.

[0005] However, it only solves the problem of light emission crosstalk, not electrical crosstalk. In the display field, crosstalk refers to the interference between light emitted by pixels of different colors, ultimately degrading the display effect. Specifically, it is divided into two types: optical crosstalk and electrical crosstalk.

[0006] Optical crosstalk, such as Figure 2 As shown in Figure a, when the pixel pitch is large, the light emitted by different pixels does not interfere with each other, and the display effect is unaffected. However, high-performance displays often have very small pixel pitches, and in tests, the emitted light interferes with each other, as shown in Figure a. Figure 2 As shown in Figure b. To solve optical crosstalk, opaque or reflective portions can be introduced, and alignment can be used to limit it, thus avoiding this phenomenon, as shown in Figure b. Figure 2 Therefore, the solution to optical crosstalk is relatively straightforward.

[0007] However, even with optical crosstalk resolved, electrical crosstalk still degrades display quality, such as... Figure 3As shown. When only want to let the red pixel (the leftmost) light, need to supply power to it, if the current indicates vertical transmission, then only the common color pixel light. But due to material properties, there will be a small amount of current horizontal transmission, at this time, green (middle) and blue (rightmost) pixel will also have weak light, resulting in the phenomenon of electrical crosstalk. For single layer OLED devices, due to the current transmission layer thickness is only nanometer nm level, and the lateral distance has micron μm level, it is difficult to transmit horizontally, and the electrical crosstalk is not serious.

[0008] In order to further improve the performance of OLED, the stack device structure will be used, such as Figure 4 As shown. Simple understanding is to connect two single layer OLED devices in series. At the connection of the two single layer OLED devices, a charge generation layer CGL needs to be introduced. Unlike the anode transmitting holes and the cathode transmitting electrons, the CGL needs to transmit both holes and electrons, and the lateral conductivity of the CGL material is particularly strong, and there is a problem of electrical crosstalk.

[0009] Therefore, in the stack OLED, it is particularly important to reduce the electrical crosstalk (lateral conductivity) of the CGL. SUMMARY

[0010] The purpose of the present application is a carbon nanotube composite charge generation layer and a preparation method thereof, by adding carbon nanotube composite material (CNTs) to the traditional charge generation layer (CGL), and orienting the carbon nanotube composite material (CNTs), using the anisotropic conductivity of carbon nanotubes (CNTs), eliminating the lateral conductivity of the charge generation layer (CGL), reducing the electrical crosstalk of the stack OLED device, and improving the optical performance of the product.

[0011] The present application also has the purpose of providing a stack OLED device comprising the above-mentioned carbon nanotube composite charge generation layer, and improving the electrical crosstalk problem of the stack OLED device.

[0012] The specific technical scheme of the present application is as follows:

[0013] A preparation method of a carbon nanotube composite charge generation layer, comprising the following steps:

[0014] 1) The ferric trioxide loaded carbon nanotube composite material is placed in a solvent, and the obtained solution is sprayed on the surface of the substrate, dried to obtain a modified base film;

[0015] 2) The modified base film of step 1) is treated under a magnetic field to obtain a modified base film with oriented arrangement of carbon nanotubes;

[0016] 3) The modified base film with oriented arrangement of carbon nanotubes is prepared into a carbon nanotube composite charge generation layer by high vacuum evaporation on the substrate.

[0017] In step 1), the ferric trioxide loaded carbon nanotube composite material is dissolved in o-xylene to form a solution with a mass concentration of 3±0.2%; and the ferric trioxide loaded carbon nanotube composite material layer is formed on the substrate by spraying in a nitrogen environment.

[0018] The substrate is selected from a substrate capable of forming a film on the surface as a carrier; and the substrate is a glass plate.

[0019] In step 1), the thickness of the ferric trioxide loaded carbon nanotube composite material layer formed on the substrate is 5-40 nm, preferably 25 nm, and the thickness is controlled by adjusting the spraying time.

[0020] In step 1), the drying is performed at 90±5°C in a nitrogen environment for 10±2 min.

[0021] In step 1), the preparation method of the ferric trioxide loaded carbon nanotube composite material is as follows:

[0022] 1-1) Preparation of carboxylated carbon nanotubes;

[0023] 1-2) After ultrasonic dispersion of the ferric salt solution and the carboxylated carbon nanotubes, an aqueous solution of sodium dodecylbenzenesulfonate is added, stirred, and then propylene oxide is added and stirred for reaction; after heating, the product is washed and dried;

[0024] 1-3) High-temperature treatment of the product to obtain a ferric trioxide loaded carbon nanotube composite material.

[0025] Step 1-1) specifically comprises: dispersing the carbon nanotube material in a mixed acid solution to form a suspension, ultrasonic treatment, filtration, and then washing and drying to obtain carboxylated carbon nanotubes CNT-COOH;

[0026] In step 1-1), the diameter of the carbon nanotube material is 6-13 nm, and the length is 0.1-1 μm.

[0027] In step 1-1), the mixed acid solution refers to a mixed solution of concentrated sulfuric acid solution and nitric acid solution, and the volume ratio of the concentrated sulfuric acid solution to the nitric acid solution is 3:1; the mass concentration of the concentrated sulfuric acid solution is 98%, and the mass concentration of the nitric acid is 70%.

[0028] In step 1-1), the amount ratio of the carbon nanotube material to the mixed acid solution is 0.013-0.016 g / mL.

[0029] In step 1-1), after ultrasonic treatment of the suspension at room temperature for 3-3.5 hours, the concentration is diluted to 50% with deionized water.

[0030] In step 1-1), the filtration refers to filtering the suspension using a polytetrafluoroethylene membrane with a pore size of 0.45 μm; the washing refers to washing to neutral with deionized water; and the drying refers to drying under vacuum at 50±5°C for 18-22 h.

[0031] In step 1-2), the mass ratio of the iron salt to the carboxylated carbon nanotubes in the iron salt solution is 3.8-4.5:1, preferably 4:1;

[0032] In step 1-2), the iron salt solution refers to an ethanol solution of the iron salt, which is obtained by placing the iron salt in anhydrous ethanol, and the concentration of the iron salt is 0.03-0.04 g / mL; and the iron salt is selected from Fe(NO3)3·9H2O;

[0033] In step 1-2), the ultrasonic dispersion is performed for 3-3.5 h;

[0034] In step 1-2), after adding the sodium dodecyl benzene sulfonate solution, stirring is performed for 30-35 min; the concentration of the sodium dodecyl benzene sulfonate solution is 1.2 mM; and the ratio of the amount of the iron salt in the iron salt solution to the sodium dodecyl benzene sulfonate solution is 1:30-35 g / mL;

[0035] In step 1-2), propylene oxide is added as a gelling agent; the ratio of the amount of the iron salt in the iron salt solution to the propylene oxide is 1:1.5-2.0 g / mL; and stirring is performed for 30-35 min after adding the propylene oxide;

[0036] In step 1-2), the heating refers to heating at 95-100°C for 70-74 h;

[0037] In step 1-2), the washing refers to rinsing with water and ethanol for 5-6 times, respectively; and the drying is performed at 50-55°C until a constant weight is obtained.

[0038] In step 1-3), high-temperature oxidation is performed in a nitrogen-oxygen mixed atmosphere environment at 500±10°C for 2-2.2 h to obtain the target product, i.e., the iron(III) oxide loaded carbon nanotube composite material. The volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixed atmosphere environment is 8:2.

[0039] In step 2), the modified base film is placed in a magnetic field with a fixed direction and a fixed frequency, specifically, a magnetic field with a strength of 0.3 T is applied to the modified base film in a top-to-bottom manner for 1 h; the strength of the magnetic field is changed to switch between 0 T and 0.3 T, and the switching frequency is 30 Hz, and the switching is performed for 20 min; then the modified base film is further fixed by heating at 90±2°C for 30±3 min in a nitrogen atmosphere; and a modified base film with oriented carbon nanotubes is prepared.

[0040] Further, the modified base film formed on the substrate has one side facing the north pole N of the magnetic field and the other side facing the south pole S of the magnetic field.

[0041] Due to the Fe2O3 particles combined on the carbon nanotubes, under the action of a magnetic field, the Fe2O3 particles will be ordered according to the direction of the magnetic field, and then the carbon nanotubes are vertically oriented and arranged; after the carbon nanotubes are vertically oriented and arranged, the vertical conductivity is not changed, and the horizontal conductivity is greatly reduced, thereby realizing the effect of eliminating horizontal conduction, see Figure 6 .

[0042] In step 3), the modified base film with oriented arrangement of carbon nanotubes is evaporated with organic materials and metal materials on one side of the carbon nanotube oriented arrangement; the metal material and the organic material are co-evaporated.

[0043] In step 3), the high vacuum evaporation controls the vacuum degree to be ≤1×10 -4 Pa, wherein the vacuum degree is preferably 5×10 -5 Pa;

[0044] In step 3), when the organic material is high-vacuum evaporated, the temperature is controlled to be 200-400℃, preferably 340℃, and the evaporation rate is wherein the evaporation rate is preferably The organic material includes but is not limited to HAT-CN, FeCl3:NPB, MoO3:NPB or F4-TCNQ:m-MTDATA;

[0045] In step 3), the metal material includes but is not limited to Li, Mg, Ca, Cs, LiF, CsF, Cs2CO3, CsN3 or Rb2CO3;

[0046] In step 3), when the organic material is high-vacuum evaporated, the temperature is controlled to be 300-650℃, preferably 550℃; and the evaporation rate is wherein the evaporation rate is preferably

[0047] In step 3), after evaporation, the thickness of the organic material and metal material layer formed by evaporation is 5-40nm, preferably 20nm.

[0048] The application provides a carbon nanotube composite charge generation layer prepared by the above method.

[0049] The application provides a laminated OLED device, specifically a laminated OLED device prepared by the above carbon nanotube composite charge generation layer.

[0050] The electrical crosstalk is different from the optical crosstalk, and the electrical crosstalk is related to material characteristics, and cannot be solved by introducing a structure change as the optical crosstalk; the stacked OLED device must have the introduction of the CGL, and the CGL itself has strong lateral conductivity, and it is critical to solve the electrical crosstalk (lateral conductivity) of the CGL. The carbon nanotube composite material CNTs is added to the traditional charge generation layer CGL, the carbon nanotube composite material CNTs is oriented, the anisotropic conductivity of the carbon nanotube CNTs is utilized, the lateral conductivity of the charge generation layer CGL is eliminated, the electrical crosstalk of the stacked OLED device is reduced, and the optical performance of the product is improved.

[0051] The carbon nanotube is a one-dimensional quantum material with a special structure, a radial size of nanometer level, and an axial size of micrometer level. The carbon nanotube is mainly composed of carbon atoms arranged in a hexagonal shape, and is a coaxial circular tube with several to tens of layers. The carbon nanotube is in a powder state in a macroscopic view, and the physical and chemical and electrical properties can be simply understood as graphite. However, due to the particularity of the structure of a single carbon nanotube, the electrical properties in the lateral direction and the longitudinal direction are quite different. The disordered carbon nanotube has no special macroscopic property, and is similar to the electrical property of graphite; the carbon nanotube in the disordered state is prepared by using a solution method, and in order to obtain the ordered state, the carbon nanotube is modified, a magnetic particle is modified on each carbon nanotube, and the carbon nanotube is prepared on a substrate by spraying, and then is dried, and the magnetic field is used to induce the orientation, so that the relatively regular carbon nanotube is obtained. The ordered arranged carbon nanotube (carbon nanotube orientation arrangement) has the special property of conductivity, and the axial conductivity is much higher than the radial conductivity,

[0052] Compared with the prior art, the carbon nanotube material in the regular arrangement is obtained, the axial conductivity is much higher than the radial conductivity, the traditional evaporation process is used, the CGL is prepared on the regularly arranged carbon nanotube layer by the thermal evaporation, and therefore the electrical crosstalk (lateral conductivity) of the CGL is reduced, and the performance of the stacked OLED device is improved. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 It is a structure schematic diagram of different structure OLED devices; a is a structure schematic diagram of a single layer OLED device, b is a structure schematic diagram of a stacked OLED device, and c is a schematic diagram of adjacent pixel light emission caused by the lateral conductivity of the CGL in the stacked OLED device;

[0054] Figure 2 It is a schematic diagram of optical crosstalk; a is a large pixel spacing, b is a small pixel spacing, and c is the introduction of non-transparency or reflection;

[0055] Figure 3 It is a schematic diagram of electrical crosstalk;

[0056] Figure 4 Schematic diagram of electrical crosstalk of stacked device structure;

[0057] Figure 5 Schematic diagram of preparation process of carbon nanotube composite material;

[0058] Figure 6 Schematic diagram of preparation process of ordered arranged carbon nanotube;

[0059] Figure 7 SEM diagram of material prepared by the present application; a is low magnification of Fe2O3 loaded carbon nanotube composite material, b is high magnification of Fe2O3 loaded carbon nanotube composite material, wherein the dotted protrusions are Fe2O3, c is unoriented carbon nanotube modified base film, d is oriented carbon nanotube oriented arrangement modified base film;

[0060] Figure 8 Schematic diagram of electrical characterization;

[0061] Figure 9 Schematic diagram of preparation of high vacuum evaporation carbon nanotube composite charge generation layer;

[0062] Figure 10 Schematic diagram of preparation of stacked OLED device using carbon nanotube composite charge generation layer; a is a schematic diagram of stacked OLED device, b is an enlarged view of 04 single layer OLED structure, c is an enlarged view of 06 single layer OLED structure, d is an enlarged view of 05 new CGL structure, which includes materials including oriented carbon nanotube composite material prepared by the present application, e is a schematic diagram of conductive principle in each direction of new CGL layer, which is carbon nanotube composite charge generation layer; Figure 10 01 is a substrate, 02 is an anode, 03 is a pixel definition layer, 04 is a single layer OLED, which includes hole injection layer 041, hole transport layer 042, light emitting layer 043, electron transport layer 044 and electron injection layer 045; 05 is a new CGL, which includes carbon nanotube oriented arrangement material 051 and n&p-CGL 052, 06 is a single layer OLED, which includes hole injection layer 061, hole transport layer 062, light emitting layer 063, electron transport layer 064, electron injection layer 065, 07 is a cathode, 08 is a light extraction layer, 09 is a thin film encapsulation layer, 10 is a color adhesive layer, and 11 is a glass cover plate. DETAILED DESCRIPTION

[0063] The carbon nanotube material was purchased from Sigma-Aldrich, CAS No.: 308068-56-6, diameter 6-13 nm, length 0.1-1 μm; Fe(NO3)3·9H2O was purchased from Sigma-Aldrich, CAS No.: 7782-61-8, purity 99.5%; anhydrous ethanol 100% purity; sodium dodecylbenzenesulfonate (NaDDBS) was purchased from Sigma-Aldrich, CAS No.: 2386-53-0, purity 99%; the propylene oxide was purchased from Sigma-Aldrich, CAS No.: 75-56-9, purity 99%.

[0064] Example 1

[0065] A method for preparing a carbon nanotube composite charge generation layer, comprising the following steps:

[0066] 1-1) 1.5 g of carbon nanotube material (CNTs), diameter 6-13 nm, length 0.1-1 μm, was first dispersed in 100 mL of mixed acid solution with a volume ratio of concentrated sulfuric acid solution and nitric acid solution of 3:1 to form a suspension, the mass concentration of the concentrated sulfuric acid solution was 98%, and the mass concentration of the nitric acid was 70%; the obtained suspension was treated with ultrasonic for 3 hours at room temperature, then the concentration was diluted to 50% with deionized water; the suspension was filtered using a 0.45 μm polytetrafluoroethylene membrane, washed with deionized water to achieve a neutral pH value, and dried at 50°C under vacuum for 20 h to obtain carboxylated carbon nanotube material (CNT-COOH).

[0067] 1-2) 0.65 g of Fe(NO3)3·9H2O was added to 20 ml of anhydrous ethanol and stirred until completely dissolved to obtain an iron salt solution, the iron salt solution was mixed with the above carboxylated carbon nanotube material, the mass ratio of Fe(NO3)3·9H2O:CNT-COOH was 4:1, ultrasonic dispersion was carried out for 3 h, 20 ml of 1.2 mM sodium dodecylbenzenesulfonate aqueous solution was added to the solution and stirred for 30 min; then, 1.2 ml of propylene oxide was added as a gelling agent and stirred for 30 min; the mixture was then placed in an oven and dried at 100°C for 72 h, the obtained powder product was washed with water and ethanol for 5 times respectively, and dried at 50°C.

[0068] 1-3) The dried product was subjected to high temperature oxidation in a furnace at 500°C in a nitrogen-oxygen mixed atmosphere environment with a volume ratio of nitrogen and oxygen of 8:2 for 2 hours to obtain the target product: iron sesquioxide loaded carbon nanotube composite material;

[0069] The characterization of the iron sesquioxide loaded carbon nanotube composite material is as follows: Figure 7, a is the low rate of Fe2O3 loaded carbon nanotube composite material, b is the high rate of Fe2O3 loaded carbon nanotube composite material, wherein the dotted protrusions are Fe2O3.

[0070] 1-4) Fe2O3 loaded carbon nanotube composite material is dissolved in o-xylene to prepare a solution with a mass concentration of 3%, and a glass substrate is prepared in a nitrogen environment using a spray coating method with a thickness of 25 nm. After spraying, dry at 90°C for 10 min in a nitrogen environment to form a Fe2O3 loaded carbon nanotube composite material layer, thereby obtaining a modified base film;

[0071] 2) Fix the direction of the magnetic field, with the side of the Fe2O3 loaded carbon nanotube composite material layer facing the south pole N of the magnetic field, and the side of the substrate facing the north pole N. Apply a magnetic field with a strength of 0.3T to the modified base film for 1h. Change the magnetic field strength to switch between 0T and 0.3T at a frequency of 30Hz for 20min, and then heat at 90°C for 30min in a nitrogen atmosphere to prepare a carbon nanotube oriented arrangement modified base film;

[0072] Figure 7 , c is the unoriented carbon nanotube modified base film, and d is the oriented carbon nanotube oriented arrangement modified base film.

[0073] The conductivity characterization principle of the oriented carbon nanotube composite material film is shown in Figure 8 , and the data is shown in Table 1:

[0074] Table 1: Conductivity values of oriented carbon nanotube composite material film

[0075]

[0076] 3) On the carbon nanotube oriented arrangement modified base film, the side with carbon nanotube oriented arrangement is evaporated with organic and metal materials, and the metal material is co-evaporated with the organic material. Control the vacuum degree to be 5×10 -5 Pa; the organic material is HAT-CN, and the evaporation rate is controlled at 340°C during evaporation. The metal material is Li, and the evaporation rate is controlled at 550°C during evaporation. The thickness of the organic material and metal material layer formed by evaporation is 20nm.

[0077] Example 2

[0078] A laminated OLED device comprising the above-mentioned carbon nanotube composite charge generation layer, the specific preparation method is:

[0079] S1, using a conventional photolithography process to prepare a patterned anode 02 on a substrate 01, wherein the substrate includes but is not limited to LTPS substrate, LTPO substrate, PI flexible substrate, CMOS drive backplane; 02 anode structure is a laminated structure or a single layer structure, the laminated structure includes but is not limited to ITO / Ag / ITO, Ti / Al / ITO, the single layer structure includes ITO or IZO; in this embodiment, the CMOS drive backplane is selected, and the laminated anode structure is Ti / Al / ITO;

[0080] S2, using a conventional deposition and photolithography process to prepare a pixel definition layer 03, wherein the pixel definition layer 03 material includes but is not limited to silicon nitride, silicon oxide, organic glue, etc., and the silicon oxide is preferred;

[0081] S1, using a conventional vacuum evaporation process to prepare a single-layer OLED 04, wherein the single-layer OLED light-emitting structure includes a hole injection layer 041, a hole transport layer 042, a light-emitting layer 043, an electron transport layer 044 and an electron injection layer 045;

[0082] S3, according to the method of embodiment 1, the prepared ferroferric oxide loaded carbon nanotube composite carbon is dissolved in o-xylene to prepare a solution with a mass concentration ratio of 3%, and a spray coating method is used to prepare on the 04 single-layer OLED in a nitrogen environment, the thickness is controlled by adjusting the spraying time, which can be selected as 5-40 nm, and the preferred thickness is 25 nm. After spraying, dry at 90°C in a nitrogen environment for 10 min, then apply a magnetic field with a strength of 0.3T on the substrate, last for 1h, change the magnetic field strength to switch between 0T and 0.3T, the switching frequency is 30Hz, and the switching time is 20min, then heat at 90°C in a nitrogen atmosphere for 30min, to prepare a modified base film 051 with oriented arrangement of carbon nanotubes;

[0083] S4, evaporating organic material and metal material on the side of the modified base film with oriented arrangement of carbon nanotubes, to prepare n&p-CGL 052, the metal material includes but is not limited to Li, Mg, Ca, Cs, LiF, CsF, Cs2CO3, CsN3 or Rb2CO3; the organic material includes but is not limited to HAT-CN, FeCl3: NPB, MoO3: NPB or F4-TCNQ: m-MTDATA; the prepared organic material and metal material layer, i.e. n&p-CGL 052, is evaporated to obtain a thickness of 5-40nm, and the preferred thickness is 20nm; at this time, the new CGL layer 05 is prepared;

[0084] S5, on the new CGL layer 05, using a conventional vacuum evaporation process to prepare a single layer OLED 06, wherein the single layer OLED 06 comprises a hole injection layer 061, a hole transport layer 062, a light-emitting layer 063, an electron transport layer 064, an electron injection layer 065;

[0085] S6, on the single layer OLED light-emitting structure 06, using a conventional vacuum evaporation process to prepare a cathode 07, and then a light extraction layer 08;

[0086] S7, on the light extraction layer 08, using a conventional deposition, photolithography process to prepare a thin film encapsulation layer 09;

[0087] S8, on the thin film encapsulation layer 09, using a conventional photolithography process to prepare a color gel layer 10;

[0088] S9, on the color gel layer 10, bonding a glass cover plate 11;

[0089] S10, 01-11 module process.

[0090] The prepared laminated OLED device is as shown in Figure 10 .

Claims

1. A method for preparing a carbon nanotube composite charge generation layer, characterized in that, The preparation method includes the following steps: 1) The ferric oxide-supported carbon nanotube composite material was placed in a solvent, and the resulting solution was sprayed onto the substrate surface and dried to obtain a modified base film; 2) The modified base film from step 1) is treated under a magnetic field to obtain a modified base film with oriented carbon nanotubes. 3) The modified base film with oriented carbon nanotubes was prepared by high vacuum evaporation of organic and metal materials to obtain a carbon nanotube composite charge generation layer on the substrate.

2. The preparation method according to claim 1, characterized in that, In step 1), the ferric oxide-supported carbon nanotube composite material is dissolved in o-xylene to prepare a solution with a mass concentration of 3 ± 0.2%; the ferric oxide-supported carbon nanotube composite material layer is formed by spraying on the substrate in a nitrogen atmosphere using a spraying method.

3. The preparation method according to claim 1, characterized in that, In step 1), the preparation method of the ferric oxide-supported carbon nanotube composite material is as follows: 1-1) Preparation of carboxylated carbon nanotubes; 1-2) After ultrasonic dispersion of iron salt solution and carboxylated carbon nanotubes, sodium dodecylbenzenesulfonate aqueous solution was added, stirred, propylene oxide was added, and the reaction was stirred; after heating, the product was washed and dried. 1-3) The product was treated at high temperature under an inert atmosphere to obtain a carbon nanotube composite material supported by ferric oxide.

4. The preparation method according to claim 3, characterized in that, The iron salt solution mentioned in steps 1-2) refers to an ethanol solution of iron salt, and the concentration of the iron salt is 0.03-0.04 g / mL; the mass ratio of iron salt to carboxylated carbon nanotubes in the iron salt solution is 3.8-4.5:

1.

5. The preparation method according to claim 3, characterized in that, Steps 1-3) Specifically, the treatment is carried out in a nitrogen environment at 500±10℃ for 2-2.2 hours.

6. The preparation method according to claim 1, characterized in that, Step 2) Specifically: Apply a magnetic field of 0.3T to the top and bottom of the modified base film for 1 hour; change the magnetic field strength to switch between 0T and 0.3T with a switching frequency of 30Hz for 20 minutes; then heat it at 90±2℃ for 30±3 minutes in a nitrogen atmosphere to prepare a modified base film with oriented carbon nanotubes.

7. The preparation method according to claim 1, characterized in that, In step 3), the vacuum level is controlled to be ≤1×10. -4 Pa high-vacuum evaporation of organic and metallic materials.

8. The preparation method according to claim 1, characterized in that, In step 3), the temperature is controlled at 300~650℃ and the evaporation rate is 0.05Å / s~1Å / s when the organic material is vapor-deposited. The temperature is controlled at 300~650℃ and the evaporation rate is 0.05Å / s~1Å / s when the metal material is vapor-deposited.

9. A carbon nanotube composite charge-generating layer prepared by the preparation method according to any one of claims 1-8.

10. A stacked OLED device, characterized in that, The stacked OLED device is prepared using the carbon nanotube composite charge generation layer described in claim 9.

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