Organic light-emitting device capable of emitting red phosphorescence and preparation method of organic light-emitting device

Abstract

The invention discloses a red phosphorescence emission organic light-emitting device and a preparation method thereof. The red phosphorescence emission organic light-emitting device is composed of a transparent glass substrate, an anode layer, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode layer. Wherein the light-emitting layer is prepared by adopting a thermally activated delayed fluorescent material as a main body and a red Ir (III) complex phosphorescent material ICziq-Ir as an object and adopting a vacuum evaporation method. The electron blocking layer is introduced, electrons can be well limited in the light-emitting layer, and high efficiency is achieved; under the driving of forward voltage, the luminescent device emits pure red phosphorescence, the maximum external quantum efficiency can reach 28.83%, and the maximum brightness can reach 33562 cd / m < 2 >; the device is mature in preparation process, the film is uniform and flat, defects are few, and excellent performance of the device is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of organic light-emitting diodes, and particularly to an organic electroluminescent device with red phosphorescent emission and a preparation method thereof. Background Art

[0002] As a new generation of display and lighting technology, organic light-emitting diodes (OLEDs) have gradually emerged in the market due to their advantages such as self-luminescence, high contrast ratio, wide viewing angle, and flexibility. Among them, red phosphorescent OLEDs play a key role in the entire OLED technology system. In traditional luminescent materials, fluorescent materials have the problem that the theoretical internal quantum efficiency limit is 25%, which restricts the further improvement of their energy utilization efficiency and luminescent performance. The emergence of phosphorescent materials has broken this limitation. They can utilize singlet and triplet excitons to emit light, and the theoretical internal quantum efficiency can reach 100%, greatly improving the luminescence efficiency and providing the possibility for realizing high-brightness and low-power consumption display and lighting applications.

[0003] Red phosphorescent OLEDs are particularly important for full-color displays. In OLED displays, an effective combination of the three primary colors of red, green, and blue is required to present rich colors. As one of the three primary colors, the color purity, luminescence efficiency, and stability of red directly affect the color expressiveness and image quality of the display. High-quality red phosphorescent materials can provide a more vivid and accurate red display effect, making the image more vivid and realistic, meeting the needs of consumers for high-quality visual experiences. In the field of lighting, red phosphorescent OLEDs can cooperate with green and blue light-emitting components to achieve efficient, stable, and color temperature-adjustable white lighting, meeting people's pursuit of energy conservation, environmental protection, and a comfortable lighting environment, showing broad application prospects in scenarios such as smart homes and commercial lighting, and promoting the development of the entire OLED industry towards higher performance and more application scenarios.

[0004] However, currently, red phosphorescent OLEDs still face some technical challenges. For example, the stability of red phosphorescent materials needs to be improved, and the problem of luminescence efficiency decay during long-term use is relatively prominent; the device preparation process is complex and the cost is high, which restricts its large-scale commercial promotion; moreover, there are certain difficulties in precisely regulating the color coordinates of red phosphorescent OLEDs and the spectral matching with other color light-emitting units. Summary of the Invention

[0005] The main object of the present invention is to provide an organic electroluminescent device with red phosphorescent emission and a preparation method thereof, aiming to solve the problems of poor stability, high cost, poor precise regulation of color coordinates, and poor spectral matching with other color light-emitting units of existing red phosphorescent OLEDs.

[0006] To achieve the above object, the present invention provides an organic electroluminescent device with red phosphorescent emission, and the organic electroluminescent device with red phosphorescent emission includes: A substrate, a conductive anode layer, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a conductive cathode are sequentially arranged from bottom to top. The light-emitting layer is composed of a thermally activated delayed fluorescence material QACN as a guest material and a red Ir(III) complex phosphorescent material ICziq-Ir as a guest material; The molecular formula of the thermally activated delayed fluorescence (TADF) material QACN is: ; The molecular formula of the red Ir(III) complex phosphorescent material ICziq-Ir is: .

[0007] The present invention also provides a preparation method of an organic electroluminescent device with red phosphorescent emission, which is applied to the preparation of the above-mentioned organic electroluminescent device with red phosphorescent emission. The preparation method of the organic electroluminescent device with red phosphorescent emission includes the following steps: Clean the substrate composed of a transparent glass substrate and a transparent conductive anode ITO, and blow it dry with nitrogen after cleaning; Perform ultraviolet light irradiation treatment on the substrate; In a high-vacuum evaporation chamber, prepare an organic thin film on the treated substrate, and sequentially arrange a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, and an electron injection layer from top to bottom to prepare the organic thin film; Prepare the cathode layer in a vacuum evaporation chamber.

[0008] The beneficial effects of the present invention are as follows: 1. By using the red Ir(III) complex phosphorescent material ICziq-Ir as a guest and introducing the thermally activated delayed fluorescence material QACN as a host, due to the material characteristics of QACN, it has good thermal stability, can be applied to the vacuum evaporation method for preparation, and the TADF characteristics of the material effectively inhibit the quenching of triplet excitons and improve the efficiency of the device; 2. By using the red Ir(III) complex phosphorescent material ICziq-Ir as a light-emitting material and introducing the QACN fluorescent material with TADF characteristics as a host into the light-emitting layer, due to the narrow emission spectrum of the red Ir(III) complex phosphorescent material, it shows pure red emission, greatly improving the performance of the pure red OLED device. The external quantum efficiency of the device is as high as 28.83%, and through the host-guest cooperation, it has a low efficiency roll-off; 3. The red Ir(III) complex phosphorescent material ICziq-Ir and the thermally activated delayed fluorescence material QACN have good thermal stability and are suitable for fabricating the light-emitting layer by vacuum evaporation. Compared with the spin-coating process, the thin film has good uniformity and density, ensuring high-quality OLEDs. Description of the Drawings

[0009] Figure 1 It is a schematic structural diagram of the organic electroluminescent device with red phosphorescent emission of the present invention; Figure 2 It is a graph of the current efficiency-luminance characteristics of the light-emitting devices in Example 1 and Example 4 provided by the present invention; Figure 3 It is a graph of the external quantum efficiency-luminance characteristics of the light-emitting devices in Example 1 and Example 4 provided by the present invention; Figure 4 It is a test graph of the emission spectrum of the light-emitting device in Example 4 of the present invention; In the figure: 1 - substrate, 2 - conductive anode layer, 3 - hole injection layer, 4 - hole transport layer, 5 - electron blocking layer, 6 - light-emitting layer, 7 - electron transport layer, 8 - electron injection layer, 9 - conductive cathode layer, 10 - negative pole of the power supply, 11 - positive pole of the power supply. Detailed Embodiments

[0010] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Generally, the components of the embodiments of the present invention described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0011] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0012] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0013] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0014] In addition, the terms "first", "second", etc. are only used for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0015] In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, terms such as "arrangement" and "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0016] The following will describe the specific embodiments of the present invention in detail with reference to the drawings.

[0017] As Figures 1-4 shown, the organic electroluminescent device emitting red phosphorescence includes: A substrate 1, a conductive anode layer 2, a hole injection layer 3, a hole transport layer 4, an electron blocking layer 5, a light-emitting layer 6, an electron transport layer 7, an electron injection layer 8, and a conductive cathode are sequentially arranged from bottom to top. The light-emitting layer 6 is composed of a thermally activated delayed fluorescence material QACN as a guest material and a red Ir(III) complex phosphorescent material ICziq-Ir as a guest material; The molecular formula of the thermally activated delayed fluorescence material QACN is: ; The molecular formula of the red Ir(III) complex phosphorescent material ICziq-Ir is: .

[0018] In one embodiment, the light-emitting layer 6 is an organic thin film formed by vacuum evaporation and mixing of the thermally activated delayed fluorescence material QACN and the red Ir(III) complex phosphorescent material ICziq-Ir; the doping mass ratio of the red Ir(III) complex phosphorescent material is 2% or 4% or 6% or 8% or 10%.

[0019] In one embodiment, the material used for the substrate 1 is at least one of glass, transparent polymer flexible material, or biodegradable flexible material; wherein the transparent polymer flexible material is selected from at least one of polyethylene, polymethyl methacrylate, polycarbonate, polyurethane, polyimide, vinyl chloride resin, or polyacrylic acid; the biodegradable flexible material is selected from at least one of plant fiber, silk fibroin, gelatin, polylactic acid, glucose, viral cellulose, polylactic acid, poly(lactic-co-glycolic acid), polyvinyl alcohol, polyvinylpyrrolidone, polycaprolactone, polyhydroxyalkanoate, polysaccharide, polyglycolic acid and its copolymer, collagen gel, fibrin gel.

[0020] In one embodiment, the material used for the conductive anode layer 2 is at least one of indium tin oxide (ITO), conductive polymer poly(3,4-ethylenedioxythiophene) / poly(styrene sulfonate) (PEDOT:PSS), graphene, carbon nanotube, metal single crystal nanowire, metal alloy nanowire, and metal heterojunction nanowire; wherein, the metal single crystal nanowire is at least one of iron nanowire, copper nanowire, silver nanowire, gold nanowire, aluminum nanowire, nickel nanowire, cobalt nanowire, manganese nanowire, cadmium nanowire, indium nanowire, tin nanowire, tungsten nanowire, or platinum nanowire; the metal alloy nanowire is at least one of copper-iron alloy nanowire, silver-iron alloy nanowire, gold-iron alloy nanowire, aluminum-iron alloy nanowire, nickel-iron alloy nanowire, cobalt-iron alloy nanowire, manganese-iron alloy nanowire, cadmium-iron alloy nanowire, indium-iron alloy nanowire, tin-iron alloy nanowire, tungsten-iron alloy nanowire, platinum-iron alloy nanowire, silver-copper alloy nanowire, gold-copper alloy nanowire, aluminum-copper alloy nanowire, nickel-copper alloy nanowire, cobalt-copper alloy nanowire, manganese-copper alloy nanowire, cadmium-copper alloy nanowire, silver-copper alloy nanowire, tin-copper alloy nanowire, tungsten-copper alloy nanowire, platinum-copper alloy nanowire, gold-silver alloy nanowire, aluminum-silver alloy nanowire, nickel-silver alloy nanowire, cobalt-silver alloy nanowire, manganese-silver alloy nanowire, cadmium-silver alloy nanowire, indium-silver alloy nanowire, tin-silver alloy nanowire, tungsten-silver alloy nanowire, platinum-silver alloy nanowire, aluminum-gold alloy nanowire, nickel-gold alloy nanowire, cobalt-gold alloy nanowire, manganese-gold alloy nanowire, cadmium-gold alloy nanowire, indium-gold alloy nanowire, tin-gold alloy nanowire, tungsten-gold alloy nanowire, cobalt-nickel alloy nanowire, manganese-nickel alloy nanowire, cadmium-nickel alloy nanowire, indium-nickel alloy nanowire, tin-nickel alloy nanowire, tungsten-nickel alloy nanowire, platinum-nickel alloy nanowire, cadmium-manganese alloy nanowire, indium-manganese alloy nanowire, tin-manganese alloy nanowire, tungsten-manganese alloy nanowire, platinum-manganese alloy nanowire, indium-cadmium alloy nanowire, tin-cadmium alloy nanowire, tungsten-cadmium alloy nanowire, platinum-cadmium alloy nanowire, tin-indium alloy nanowire, tungsten-indium alloy nanowire, platinum-indium alloy nanowire, tungsten-tin alloy nanowire, platinum-tin alloy nanowire, or platinum-tungsten alloy nanowire;The metal heterojunction nanowires are at least one of copper-iron heterojunction nanowires, silver-iron heterojunction nanowires, gold-iron heterojunction nanowires, aluminum-iron heterojunction nanowires, nickel-iron heterojunction nanowires, cobalt-iron heterojunction nanowires, manganese-iron heterojunction nanowires, cadmium-iron heterojunction nanowires, indium-iron heterojunction nanowires, tin-iron heterojunction nanowires, tungsten-iron heterojunction nanowires, platinum-iron heterojunction nanowires, silver-copper heterojunction nanowires, gold-copper heterojunction nanowires, aluminum-copper heterojunction nanowires, nickel-copper heterojunction nanowires, cobalt-copper heterojunction nanowires, manganese-copper heterojunction nanowires, cadmium-copper heterojunction nanowires, silver-copper heterojunction nanowires, tin-copper heterojunction nanowires, tungsten-copper heterojunction nanowires, platinum-copper heterojunction nanowires, gold-silver heterojunction nanowires, aluminum-silver heterojunction nanowires, nickel-silver heterojunction nanowires, cobalt-silver heterojunction nanowires, manganese-silver heterojunction nanowires, cadmium-silver heterojunction nanowires, indium-silver heterojunction nanowires, tin-silver heterojunction nanowires, tungsten-silver heterojunction nanowires, platinum-silver heterojunction nanowires, aluminum-gold heterojunction nanowires, nickel-gold heterojunction nanowires, cobalt-gold heterojunction nanowires, manganese-gold heterojunction nanowires, cadmium-gold heterojunction nanowires, indium-gold heterojunction nanowires, tin-gold heterojunction nanowires, tungsten-gold heterojunction nanowires, cobalt-nickel heterojunction nanowires, manganese-nickel heterojunction nanowires, cadmium-nickel heterojunction nanowires, indium-nickel heterojunction nanowires, tin-nickel heterojunction nanowires, tungsten-nickel heterojunction nanowires, platinum-nickel heterojunction nanowires, cadmium-manganese heterojunction nanowires, indium-manganese heterojunction nanowires, tin-manganese heterojunction nanowires, tungsten-manganese heterojunction nanowires, platinum-manganese heterojunction nanowires, indium-cadmium heterojunction nanowires, tin-cadmium heterojunction nanowires, tungsten-cadmium heterojunction nanowires, platinum-cadmium heterojunction nanowires, tin-indium heterojunction nanowires, tungsten-indium heterojunction nanowires, platinum-indium heterojunction nanowires, tungsten-tin heterojunction nanowires, platinum-tin heterojunction nanowires or platinum-tungsten heterojunction nanowires.

[0021] In one embodiment, the material used for the hole injection layer 3 is molybdenum trioxide and 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene.

[0022] In one embodiment, the material of the hole transport layer 4 is any one of aromatic diamine compounds, aromatic triamine compounds, carbazole compounds, star-shaped triphenylamine compounds, furan compounds, spiral structure compounds, and polymer materials.

[0023] In one embodiment, the material of the electron blocking layer 5 is 4,4',4'-tris(carbazol-9-yl)triphenylamine.

[0024] In one embodiment, the material of the electron transport layer 7 is any one of metal oxides, metal complexes, oxadiazole compounds, quinoxaline compounds, nitrogen-containing heterocyclic compounds, anthracene compounds, organosilicon materials, organoboron materials, and organosulfur materials.

[0025] In one embodiment, the material of the electron injection layer 8 is LiF.

[0026] In one embodiment, the conductive cathode is a metal thin film or an alloy thin film. The metal thin film is a lithium, magnesium, calcium, strontium, aluminum, or indium thin film, and the alloy thin film is an alloy of lithium, magnesium, calcium, strontium, aluminum, or indium with copper, gold, or silver.

[0027] In one embodiment, the thickness of the light-emitting layer 6 is 20 - 25 nm, the thickness of the hole injection layer 3 is 3 - 10 nm, the thickness of the hole transport layer 4 is 20 - 50 nm, the thickness of the electron blocking layer 5 is 5 - 15 nm, the thickness of the electron injection layer 8 is 1 nm, the thickness of the electron transport layer 7 is 20 - 50 nm, and the thickness of the conductive cathode is 100 nm - 110 nm.

[0028] The present invention also provides a method for manufacturing an organic electroluminescent device with red phosphorescent emission. This method is applied to the manufacture of the above-mentioned organic electroluminescent device with red phosphorescent emission. The method for manufacturing the organic electroluminescent device with red phosphorescent emission includes the following steps: Clean the substrate composed of the transparent glass substrate 1 and the transparent conductive anode ITO, and dry it with nitrogen after cleaning; Perform ultraviolet light irradiation treatment on the substrate; In a high-vacuum evaporation chamber, prepare the organic thin film on the processed substrate. The hole injection layer 3, hole transport layer 4, electron blocking layer 5, light-emitting layer 6, electron transport layer 7, and electron injection layer 8 are sequentially arranged from top to bottom to prepare the organic thin film; Prepare the cathode layer in the vacuum evaporation chamber.

[0029] Example 1 (control group): The hole injection layer of the light-emitting device is HAT-CN, the hole transport layer is TAPC, the electron blocking layer is TCTA, the light-emitting layer is ICziq-Ir, the electron transport layer is TmPyPB, the electron injection layer is LiF, and the cathode is Al; the entire structure of the light-emitting device is: Glass substrate / ITO / HAT-CN(5nm) / TAPC(10nm) / TCTA(30nm) / ICziq-Ir (20nm) / TmPyPB(30nm) / LiF(1nm) / Al(100nm).

[0030] Its manufacturing method is as follows: ① Ultrasonically clean the transparent conductive substrate ITO glass with detergent, acetone solution, deionized water, and isopropyl alcohol solution, and dry it with dry nitrogen after cleaning. The ITO film on the glass substrate serves as the anode layer of the light-emitting device, and the film thickness is 100 nm; ②Treat the ITO glass substrate by irradiating it with ultraviolet light. Place the petri dish containing the glass substrate inside and perform ultraviolet treatment for 30 minutes; ③The treated substrate is placed in an evaporation chamber with a high vacuum degree. The vacuum degree of the vacuum environment is maintained below 2×10-4 Pa. Evaporate HAT-CN in sequence with a film thickness of 5 nm, TAPC with a film thickness of 10 nm, TCTA with a film thickness of 30 nm, ICziq-Ir with a film thickness of 20 nm, TmPyPB with a film thickness of 30 nm, LiF with a film thickness of 1 nm. The evaporation rate of each organic layer is 1 Å / s, and the evaporation rate of LiF is 0.1 Å / s. The evaporation rate and thickness are monitored by a film thickness meter; ④After evaporation, prepare the metal electrode. Under the condition of a pressure of 4×10 -4 Pa, control the evaporation rate of Al at 3 - 5 Å / s, and the film layer thickness is 100 nm. The evaporation rate and thickness are monitored by a film thickness meter.

[0031] Under standard test conditions, the maximum current efficiency of the light-emitting device is 6.56 cd / A, the highest external quantum efficiency reaches 8.02%, and the highest brightness is 8306 cd / m 2 , and its current efficiency - brightness characteristic curve is as Figure 2 shown, and the external quantum efficiency - brightness characteristic curve is as Figure 3 shown.

[0032] Example 2: The hole injection layer of the light-emitting device is HAT-CN, the hole transport layer is TAPC, the electron blocking layer is TCTA, the light-emitting layer is QACN: 2wt% ICziq-Ir, the electron transport layer is TmPyPB, the electron injection layer is LiF, and the cathode is Al; the structure of the entire light-emitting device is: Glass substrate / ITO / HAT-CN(5nm) / TAPC(10nm) / TCTA(30nm) / QACN: 2wt% ICziq-Ir(20nm) / TmPyPB(30nm) / LiF(1nm) / Al(100nm).

[0033] The preparation process of this light-emitting device is similar to that of Example 1.

[0034] Under standard test conditions, the maximum current efficiency of the device is 16.43 cd / A, the highest external quantum efficiency reaches 20.18%, and the highest brightness is 15632 cd / m 2 .

[0035] Example 3: The hole injection layer of the light-emitting device is HAT-CN, the hole transport layer is TAPC, the electron blocking layer is TCTA, the light-emitting layer is QACN: 4wt% ICziq-Ir, the electron transport layer is TmPyPB, the electron injection layer is LiF, and the cathode is Al; the structure of the entire light-emitting device is: Glass substrate / ITO / HAT-CN(5nm) / TAPC(10nm) / TCTA(30nm) / QACN: 4wt% ICziq-Ir(20nm) / TmPyPB(30nm) / LiF(1nm) / Al(100nm).

[0036] The preparation process of this light-emitting device is similar to that of Example 1.

[0037] Under standard test conditions, the maximum current efficiency of the device is 24.26 cd / A, the maximum external quantum efficiency reaches 23.45%, and the maximum brightness is 22529 cd / m 2 .

[0038] Example 4: The hole injection layer of the light-emitting device is HAT-CN, the hole transport layer is TAPC, the electron blocking layer is TCTA, the light-emitting layer is QACN: 6wt% ICziq-Ir, the electron transport layer is TmPyPB, the electron injection layer is LiF, and the cathode is Al; the structure of the entire light-emitting device is: Glass substrate / ITO / HAT-CN(5nm) / TAPC(10nm) / TCTA(30nm) / QACN: 6wt% ICziq-Ir(20nm) / TmPyPB(30nm) / LiF(1nm) / Al(100nm).

[0039] The preparation process of this light-emitting device is similar to that of Example 1.

[0040] Under standard test conditions, the maximum current efficiency of the device is 37.31 cd / A, the maximum external quantum efficiency reaches 28.83%, and the maximum brightness is 33562 cd / m 2 , and its current efficiency-brightness characteristic curve is as Figure 2 shown, the external quantum efficiency-brightness characteristic curve is as Figure 3 shown, and the test curve of the emission spectrum is as Figure 4 shown.

[0041] Example 5: The hole injection layer of the light-emitting device is HAT-CN, the hole transport layer is TAPC, the electron blocking layer is TCTA, the light-emitting layer is QACN: 8wt% ICziq-Ir, the electron transport layer is TmPyPB, the electron injection layer is LiF, and the cathode is Al; the structure of the entire light-emitting device is: Glass substrate / ITO / HAT-CN(5nm) / TAPC(10nm) / TCTA(30nm) / QACN: 8wt% ICziq-Ir(20nm) / TmPyPB(30nm) / LiF(1nm) / Al(100nm).

[0042] The preparation process of this light-emitting device is similar to that of Example 1.

[0043] Under standard test conditions, the maximum current efficiency of the device is 28.36 cd / A, the maximum external quantum efficiency reaches 25.49%, and the maximum brightness is 22604 cd / m 2 .

[0044] Example 6: The hole injection layer of the light-emitting device is HAT-CN, the hole transport layer is TAPC, the electron blocking layer is TCTA, the light-emitting layer is QACN: 10wt% ICziq-Ir, the electron transport layer is TmPyPB, the electron injection layer is LiF, and the cathode is Al; the structure of the entire light-emitting device is: Glass substrate / ITO / HAT-CN(5nm) / TAPC(10nm) / TCTA(30nm) / QACN: 10wt% ICziq-Ir(20nm) / TmPyPB(30nm) / LiF(1nm) / Al(100nm).

[0045] The preparation process of this light-emitting device is similar to that of Example 1.

[0046] Under standard test conditions, its maximum current efficiency is 17.71 cd / A, the maximum external quantum efficiency reaches 21.24%, and the maximum brightness is 16621 cd / m 2 .

[0047]

[0048] Table 1 Performance parameters of organic light-emitting diodes As can be seen from the above, by introducing the thermally activated delayed fluorescent material QACN as a host in the red Ir(III) phosphorescent light-emitting layer 6 (i.e., the organic light-emitting diodes prepared in Examples 2-6), the luminous efficiency and brightness of the light-emitting device are significantly improved compared to the organic light-emitting diode prepared in Example 1 using a pure red Ir(III) phosphorescent material as the light-emitting layer 6. This is because the QACN material, as the host material of the light-emitting layer 6, can better utilize triplet excitons, suppressing exciton concentration quenching and significantly increasing the probability of exciton radiative recombination. Furthermore, the QACN material has bipolar transport capability. As the host material of the light-emitting layer 6, it can balance carrier transport, significantly improving the performance of the light-emitting device. Repeated experiments have shown that the device performance is optimal when the red Ir(III) phosphorescent material is doped at a concentration of 6% as the guest doping material in the light-emitting layer 6.

[0049] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An organic electroluminescent device emitting red phosphorescence, characterized in that, The organic electroluminescent device with red phosphorescent emission includes: A substrate, a conductive anode layer, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a conductive cathode are sequentially arranged from bottom to top. The light-emitting layer is composed of a thermally activated delayed fluorescence material QACN as a guest material and a red Ir(III) complex phosphorescent material ICziq-Ir as a guest material; The molecular formula of the thermally activated delayed fluorescence material QACN is: ； The molecular formula of the red Ir(III) complex phosphorescent material ICziq-Ir is: 。 2. The organic electroluminescent device with red phosphorescent emission according to claim 1, characterized in that, The light-emitting layer is an organic thin film formed by vacuum evaporation and mixing of the thermally activated delayed fluorescence material QACN and the red Ir(III) complex phosphorescent material ICziq-Ir. The doping mass ratio of the red Ir(III) complex phosphorescent material is 2% or 4% or 6% or 8% or 10%.

3. The organic electroluminescent device with red phosphorescent emission according to claim 1, wherein The material of the substrate is at least one of glass, a transparent polymer flexible material, or a biodegradable flexible material; the transparent polymer flexible material is at least one of polyethylene, polymethyl methacrylate, polycarbonate, polyurethane, polyimide, vinyl chloride resin, or polyacrylic acid; the biodegradable flexible material is at least one of plant fiber, silk fibroin, gelatin, polylactic acid, glucose, viral cellulose, polylactic acid, poly(lactic-co-glycolic acid), polyvinyl alcohol, polyvinylpyrrolidone, polycaprolactone, polyhydroxyalkanoate, polysaccharide, polyol acid and its copolymer, collagen gel, fibrin gel.

4. The organic electroluminescent device with red phosphorescent emission according to claim 1, characterized in that, The material of the conductive anode layer is at least one of indium tin oxide (ITO), conductive polymer poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonate) (PEDOT:PSS), graphene, carbon nanotube, metal single-crystal nanowire, metal alloy nanowire, and metal heterojunction nanowire; the metal single-crystal nanowire is at least one of iron nanowire, copper nanowire, silver nanowire, gold nanowire, aluminum nanowire, nickel nanowire, cobalt nanowire, manganese nanowire, cadmium nanowire, indium nanowire, tin nanowire, tungsten nanowire, and platinum nanowire; the metal alloy nanowire is at least one of copper-iron alloy nanowire, silver-iron alloy nanowire, gold-iron alloy nanowire, aluminum-iron alloy nanowire, nickel-iron alloy nanowire, cobalt-iron alloy nanowire, manganese-iron alloy nanowire, cadmium-iron alloy nanowire, indium-iron alloy nanowire, tin-iron alloy nanowire, tungsten-iron alloy nanowire, platinum-iron alloy nanowire, silver-copper alloy nanowire, gold-copper alloy nanowire, aluminum-copper alloy nanowire, nickel-copper alloy nanowire, cobalt-copper alloy nanowire, manganese-copper alloy nanowire, cadmium-copper alloy nanowire, silver-copper alloy nanowire, tin-copper alloy nanowire, tungsten-copper alloy nanowire, platinum-copper alloy nanowire, gold-silver alloy nanowire, aluminum-silver alloy nanowire, nickel-silver alloy nanowire, cobalt-silver alloy nanowire, manganese-silver alloy nanowire, cadmium-silver alloy nanowire, indium-silver alloy nanowire, tin-silver alloy nanowire, tungsten-silver alloy nanowire, platinum-silver alloy nanowire, aluminum-gold alloy nanowire, nickel-gold alloy nanowire, cobalt-gold alloy nanowire, manganese-gold alloy nanowire, cadmium-gold alloy nanowire, indium-gold alloy nanowire, tin-gold alloy nanowire, tungsten-gold alloy nanowire, cobalt-nickel alloy nanowire, manganese-nickel alloy nanowire, cadmium-nickel alloy nanowire, indium-nickel alloy nanowire, tin-nickel alloy nanowire, tungsten-nickel alloy nanowire, platinum-nickel alloy nanowire, cadmium-manganese alloy nanowire, indium-manganese alloy nanowire, tin-manganese alloy nanowire, tungsten-manganese alloy nanowire, platinum-manganese alloy nanowire, indium-cadmium alloy nanowire, tin-cadmium alloy nanowire, tungsten-cadmium alloy nanowire, platinum-cadmium alloy nanowire, tin-indium alloy nanowire, tungsten-indium alloy nanowire, platinum-indium alloy nanowire, tungsten-tin alloy nanowire, platinum-tin alloy nanowire, and platinum-tungsten alloy nanowire;The metal heterojunction nanowires are at least one of copper-iron heterojunction nanowires, silver-iron heterojunction nanowires, gold-iron heterojunction nanowires, aluminum-iron heterojunction nanowires, nickel-iron heterojunction nanowires, cobalt-iron heterojunction nanowires, manganese-iron heterojunction nanowires, cadmium-iron heterojunction nanowires, indium-iron heterojunction nanowires, tin-iron heterojunction nanowires, tungsten-iron heterojunction nanowires, platinum-iron heterojunction nanowires, silver-copper heterojunction nanowires, gold-copper heterojunction nanowires, aluminum-copper heterojunction nanowires, nickel-copper heterojunction nanowires, cobalt-copper heterojunction nanowires, manganese-copper heterojunction nanowires, cadmium-copper heterojunction nanowires, silver-copper heterojunction nanowires, tin-copper heterojunction nanowires, tungsten-copper heterojunction nanowires, platinum-copper heterojunction nanowires, gold-silver heterojunction nanowires, aluminum-silver heterojunction nanowires, nickel-silver heterojunction nanowires, cobalt-silver heterojunction nanowires, manganese-silver heterojunction nanowires, cadmium-silver heterojunction nanowires, indium-silver heterojunction nanowires, tin-silver heterojunction nanowires, tungsten-silver heterojunction nanowires, platinum-silver heterojunction nanowires, aluminum-gold heterojunction nanowires, nickel-gold heterojunction nanowires, cobalt-gold heterojunction nanowires, manganese-gold heterojunction nanowires, cadmium-gold heterojunction nanowires, indium-gold heterojunction nanowires, tin-gold heterojunction nanowires, tungsten-gold heterojunction nanowires, cobalt-nickel heterojunction nanowires, manganese-nickel heterojunction nanowires, cadmium-nickel heterojunction nanowires, indium-nickel heterojunction nanowires, tin-nickel heterojunction nanowires, tungsten-nickel heterojunction nanowires, platinum-nickel heterojunction nanowires, cadmium-manganese heterojunction nanowires, indium-manganese heterojunction nanowires, tin-manganese heterojunction nanowires, tungsten-manganese heterojunction nanowires, platinum-manganese heterojunction nanowires, indium-cadmium heterojunction nanowires, tin-cadmium heterojunction nanowires, tungsten-cadmium heterojunction nanowires, platinum-cadmium heterojunction nanowires, tin-indium heterojunction nanowires, tungsten-indium heterojunction nanowires, platinum-indium heterojunction nanowires, tungsten-tin heterojunction nanowires, platinum-tin heterojunction nanowires or platinum-tungsten heterojunction nanowires.

5. The organic electroluminescent device with red phosphorescent emission according to claim 1, characterized in that, The material of the hole injection layer is molybdenum trioxide and 2, 3, 6, 7, 10, 11-hexacyano-1, 4, 5, 8, 9, 12-hexaazatriphenylene.

6. The organic electroluminescent device emitting red phosphorescence according to claim 1, wherein The material of the hole transport layer is any one of aromatic diamine compounds, aromatic triamine compounds, carbazole compounds, star-shaped triphenylamine compounds, furan compounds, spiral structure compounds, and polymer materials.

7. The organic electroluminescent device with red phosphorescent emission according to claim 1, characterized in that, The material of the electron blocking layer is 4,4',4'-tris(carbazol-9-yl)triphenylamine.

8. The organic electroluminescent device with red phosphorescent emission according to claim 1, wherein The material of the electron transport layer is any one of metal oxides, metal complexes, oxadiazole compounds, quinoxaline compounds, nitrogen-containing heterocyclic compounds, anthracene compounds, organosilicon materials, organoboron materials, and organosulfur materials.

9. The organic electroluminescent device emitting red phosphorescence according to claim 1, wherein, The material of the electron injection layer is LiF.

10. The organic electroluminescent device with red phosphorescent emission according to claim 1, characterized in that, The conductive cathode is a metal thin film or an alloy thin film. The metal thin film is a lithium, magnesium, calcium, strontium, aluminum, or indium thin film, and the alloy thin film is an alloy of lithium, magnesium, calcium, strontium, aluminum, indium and copper, gold, or silver.

11. The organic electroluminescent device emitting red phosphorescence according to claim 1, characterized in that, The thickness of the light-emitting layer is 20~25nm, the thickness of the hole injection layer is 3~10nm, the thickness of the hole transport layer is 20~50nm, the thickness of the electron blocking layer is 5~15nm, the thickness of the electron injection layer is 1nm, the thickness of the electron transport layer is 20~50nm, and the thickness of the conductive cathode is 100nm~110nm.

12. A method for preparing an organic electroluminescent device with red phosphorescent emission, which is applied to the preparation of the organic electroluminescent device with red phosphorescent emission as described in any one of claims 1-11, characterized in that, The preparation method of the organic electroluminescent device with red phosphorescent emission includes the following steps: Clean the substrate composed of a transparent glass substrate and a transparent conductive anode ITO, and dry it with nitrogen after cleaning; Irradiate the substrate with ultraviolet light; In an evaporation chamber with a high vacuum degree, prepare an organic thin film on the treated substrate, and sequentially set a hole injection layer, a hole transport layer, an electron blocking layer, a light emitting layer, an electron transport layer, and an electron injection layer from top to bottom to prepare the organic thin film; Prepare a cathode layer in a vacuum evaporation chamber.

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