CN115513388A

CN115513388A - Electron transport material, display device and display device manufacturing method

Info

Publication number: CN115513388A
Application number: CN202110691474.5A
Authority: CN
Inventors: 王士攀
Original assignee: Guangdong Juhua Printing Display Technology Co Ltd
Current assignee: Guangdong Juhua Printing Display Technology Co Ltd
Priority date: 2021-06-22
Filing date: 2021-06-22
Publication date: 2022-12-23

Abstract

The application discloses an electron transport material, a display device and a preparation method of the display device, wherein the electron transport material comprises a host material and an object material; when the electron transport material is used for preparing an electron transport layer in a red sub-pixel, the mass percentage of the guest material in the electron transport material is M1, when the electron transport material is used for preparing an electron transport layer in a green sub-pixel, the mass percentage of the guest material in the electron transport material is M2, and when the electron transport material is used for preparing an electron transport layer in a blue sub-pixel, the mass percentage of the guest material in the electron transport material is M3, M1= M2< M3, or M1< M2= M3 or M1< M2< M3. The optimization of the respective performances of the red, green and blue light-emitting devices is realized.

Description

Electron transport material, display device and preparation method of display device

Technical Field

The application relates to the technical field of display, in particular to an electronic transmission material, a display device and a preparation method of the display device.

Background

An Organic Light Emitting Diode (OLED), i.e., an OLED, is a self-luminous display that emits Light through excitons generated by recombination of electrons and holes injected under an electric field at an Organic Light Emitting material, does not require an additional Light source, has ultra-high contrast, can realize advantages of ultra-lightness, ultra-thinness, flexibility, and the like, and becomes a next generation of spotlighted display technology.

The preparation method of the OLED mainly comprises two modes of evaporation and printing, compared with the evaporation OLED technology, the printing OLED technology has the advantages of no need of high vacuum, low equipment cost, simple process, less material consumption and the like, and becomes the development key point of the medium-size and large-size OLED display technology. The manufacturing method of the full-color printing OLED mainly adopts three colors of red, green and blue (R, G and B for short) which are parallelly and independently emitted, and because the emitting materials of the R, the G and the B are different, the required charge transmission balance and exciton recombination zone positions are also different, so that the performance of the RGB device is different, and the performance of the RGB device cannot achieve the respective optimal effect.

Disclosure of Invention

The embodiment of the application provides an electron transport material, a display device and a preparation method of the display device, and aims to solve the technical problem that the performances of red, green and blue light-emitting devices cannot achieve respective optimal effects.

The embodiment of the application provides an electron transport material, which comprises a host material and a guest material;

when the electron transport material is used for preparing an electron transport layer in a red sub-pixel, the mass percentage of the guest material in the electron transport material is M1, when the electron transport material is used for preparing an electron transport layer in a green sub-pixel, the mass percentage of the guest material in the electron transport material is M2, and when the electron transport material is used for preparing an electron transport layer in a blue sub-pixel, the mass percentage of the guest material in the electron transport material is M3, M1= M2< M3, or M1< M2= M3 or M1< M2< M3.

Optionally, in some embodiments of the present application, M1 is between 30% -60%, M2 is between 40% -70%, M3 is between 60% -80%,

preferably, the host material is selected from at least one of 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene, 1, 3-bis [5- (4-tert-butylphenyl) -2- [1,3,4] oxadiazolyl ] benzene, tris (2, 4, 6-trimethyl-3- (pyridin-3-yl) phenyl) borane, 1,3, 5-tris [ (3-pyridyl) -3-phenyl ] benzene, 1,3, 5-tris (diphenyl-phosphoryl-phen-3-yl) benzene, 2, 7-bis (diphenylphosphino) -9,9 '-spirobifluorene, poly [ (9, 9-bis (3' - ((N, N-dimethyl) -N-ethylammonium) -propyl) -2, 7-fluorene) -ALT-2,7- (9, 9-dioctylfluorene) ] -dibromide,

still preferably, the guest material is at least one selected from the group consisting of lithium 8-hydroxyquinolinate, sodium 8-hydroxyquinolinate, cesium 8-hydroxyquinolinate, lithium phenolpyridinium, lithium acetate, sodium acetate, cesium acetate, lithium carbonate, and cesium carbonate.

The embodiment of the application provides a display device, which is provided with a red sub-pixel area, a green sub-pixel area and a blue sub-pixel area, wherein the display device comprises an electron transport layer, the electron transport layer comprises an electron transport material, and the electron transport material comprises a host material and a guest material;

wherein, in the red sub-pixel region, the mass percentage of the guest material in the electron transport material is M1, in the green sub-pixel region, the mass percentage of the guest material in the electron transport material is M2, and in the blue sub-pixel region, the mass percentage of the guest material in the electron transport material is M3, M1= M2< M3, or M1< M2= M3 or M1< M2< M3.

Optionally, in some embodiments of the present application, M1 is between 30% -60%, M2 is between 40% -70%, and M3 is between 60% -80%.

Optionally, in some embodiments of the present application, the electron transport layer includes a first sub electron transport layer, a second sub electron transport layer, and a third sub electron transport layer, the first sub electron transport layer is located in the red sub-pixel region, the second sub electron transport layer is located in the green sub-pixel region, the third sub electron transport layer is located in the blue sub-pixel region, and thicknesses of the first sub electron transport layer, the second sub electron transport layer, and the third sub electron transport layer increase in sequence.

Optionally, in some embodiments of the present application, the thickness of the first sub electron transport layer is 20nm to 30nm, the thickness of the second sub electron transport layer is 30nm to 40nm, and the thickness of the third sub electron transport layer is 40nm to 50nm.

Optionally, in some embodiments herein, the host material is selected from at least one of 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene, 1, 3-bis [5- (4-tert-butylphenyl) -2- [1,3,4] oxadiazolyl ] benzene, tris (2, 4, 6-trimethyl-3- (pyridin-3-yl) phenyl) borane, 1,3, 5-tris [ (3-pyridyl) -3-phenyl ] benzene, 1,3, 5-tris (diphenyl-phosphoryl-phen-3-yl) benzene, 2, 7-bis (diphenylphosphino) -9,9 '-spirobifluorene, poly [ (9, 9-bis (3' - ((N, N-dimethyl) -N-ethylammonium) -propyl) -2, 7-fluorene) -ALT-2,7- (9, 9-dioctylfluorene) ] -dibromide,

preferably, the guest material is selected from at least one of 8-hydroxyquinolinato lithium, 8-hydroxyquinolinato sodium, 8-hydroxyquinolinato cesium, phenolpyridinato lithium, lithium acetate, sodium acetate, cesium acetate, lithium carbonate, and cesium carbonate.

The embodiment of the application also provides a preparation method of the display device, which comprises the following steps:

providing an electron transport material to form an electron transport layer, wherein the electron transport material comprises a host material and a guest material;

the display device has a red sub-pixel region, a green sub-pixel region and a blue sub-pixel region in the red sub-pixel region, the mass percentage of the guest material in the electron transport material is M1, the mass percentage of the guest material in the electron transport material in the green sub-pixel region is M2, and the mass percentage of the guest material in the electron transport material in the blue sub-pixel region is M3, M1= M2< M3, or M1< M2= M3 or M1< M2< M3.

Optionally, in some embodiments herein, M1 is between 30% -60%, M2 is between 40% -70%, M3 is between 60% -80%,

preferably, the host material is selected from at least one of 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene, 1, 3-bis [5- (4-tert-butylphenyl) -2- [1,3,4] oxadiazolyl ] benzene, tris (2, 4, 6-trimethyl-3- (pyridin-3-yl) phenyl) borane, 1,3, 5-tris [ (3-pyridyl) -3-phenyl ] benzene, 1,3, 5-tris (diphenyl-phosphoryl-phen-3-yl) benzene, 2, 7-bis (diphenylphosphino) -9,9 '-spirobifluorene, poly [ (9, 9-bis (3' - ((N, N-dimethyl) -N-ethylammonium) -propyl) -2, 7-fluorene) -ALT-2,7- (9, 9-dioctylfluorene) ] -dibromo,

Compared with the electron transport material in the prior art, the electron transport material provided by the application comprises a host material and an object material, when the electron transport material is respectively used for preparing the electron transport layers of the sub-pixels with three colors of red, green and blue, the mass percentages of the object material in the electron transport material are respectively M1, M2 and M3, and M1= M2< M3, or M1< M2= M3 or M1< M2< M3, so that when the electron transport material proportion in the proportion is applied to the electron transport layers in the light emitting devices with three colors of red, green and blue, the prepared three light emitting devices with three colors of red, green and blue can respectively take better consideration of the device efficiency and the service life, and further, the optimization of the respective performances of the three light emitting devices with three colors of red, green and blue is realized.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the description below are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a display device provided in the present application.

Fig. 2 is a schematic flow chart of a method for manufacturing a display device provided in the present application.

Fig. 3 is a schematic structural view of a display device manufactured by the method of manufacturing a display device shown in fig. 2.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. Furthermore, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are given by way of illustration and explanation only, and are not intended to limit the scope of the invention. In this application, where the context requires otherwise, the words "upper" and "lower" used in relation to the device in use or operation will generally refer to the upper and lower extremities of the device, particularly as oriented in the drawing figures; while "inner" and "outer" are with respect to the outline of the device.

Embodiments of the present application provide an electron transport material, a display device, and a method for manufacturing a display device, which are described in detail below. It should be noted that the following description of the embodiments is not intended to limit the preferred order of the embodiments.

The embodiment of the application provides an electron transport material which comprises a host material and a guest material. When the electron transport material is used for preparing an electron transport layer in a red sub-pixel, the mass percentage of the guest material in the electron transport material is M1. When the electron transport material is used for preparing an electron transport layer in a green sub-pixel, the mass percentage of the guest material in the electron transport material is M2. When the electron transport material is used for preparing an electron transport layer in a blue sub-pixel, the mass percentage of the guest material in the electron transport material is M3. Wherein M1= M2< M3, or M1< M2= M3 or M1< M2< M3.

Therefore, in the electron transport material provided in this embodiment, when the electron transport material is used to prepare electron transport layers in light emitting devices of three colors of red, green, and blue, the mass percentages of the guest materials in the electron transport material are M1, M2, and M3, respectively, and M1= M2< M3, or M1< M2= M3, or M1< M2< M3, respectively, so that when the electron transport material ratios of the above proportions are applied to the electron transport layers in sub-pixels of three colors of red, green, and blue, the prepared red, green, and blue light emitting devices can simultaneously achieve better device efficiency and lifetime, and further, the respective performance of the red, green, and blue light emitting devices can be optimized.

In this embodiment, the electron transport material is composed of a host material and a guest material. The host material is selected from at least one of 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene, 1, 3-bis [5- (4-tert-butylphenyl) -2- [1,3,4] oxadiazolyl ] benzene, tris (2, 4, 6-trimethyl-3- (pyridin-3-yl) phenyl) borane, 1,3, 5-tris [ (3-pyridyl) -3-phenyl ] benzene, 1,3, 5-tris (diphenyl-phosphoryl-phen-3-yl) benzene, 2, 7-bis (diphenylphosphinyl) -9,9 '-spirobifluorene, poly [ (9, 9-bis (3' - ((N, N-dimethyl) -N-ethylammonium) -propyl) -2, 7-fluorene) -ALT-2,7- (9, 9-dioctylfluorene) ] -dibromo. The guest material is at least one selected from 8-hydroxyquinoline lithium, 8-hydroxyquinoline sodium, 8-hydroxyquinoline cesium, phenol-based pyridine lithium, lithium acetate, sodium acetate, cesium acetate, lithium carbonate and cesium carbonate.

Wherein, M1 is between 30% and 60%. M2 is between 40% and 70%. M3 is between 60% and 80%. In particular, M1 is 30% to 60%, such as may be 30%, 35%, 40%, 45%, 50%, 55% or 60%. M2 is 40% to 70%, such as may be 40%, 45%, 50%, 55%, 60%, 65% or 70%. M3 is 60% to 80%, such as 60%, 65%, 70%, 75% or 80%.

In this example, M1< M2< M3, M1 is 40%, M2 is 70%, and M3 is 80%. Under the proportion, when the electron transport layer is applied to the electron transport layers of the light emitting devices with the three colors of red, green and blue, the matching effect of the performances of the light emitting devices with the three colors of red, green and blue can be further improved, so that the optimization of the performances of the light emitting devices with the three colors of red, green and blue can be more favorably realized.

Referring to fig. 1, an embodiment of the present disclosure further provides a display device 100. The display device 100 has a red sub-pixel region 10A, a green sub-pixel region 10B, and a blue sub-pixel region 10C. Display device 100 includes electron transport layer 70. The electron transport layer 70 includes an electron transport material. The electron transport material includes a host material and a guest material. In the red sub-pixel region 10A, the mass percentage of the guest material in the electron transport material is M1. In the green sub-pixel region 10B, the mass percentage of the guest material in the electron transport material is M2. In the blue sub-pixel region 10C, the mass percentage of the guest material in the electron transport material is M3. Wherein M1= M2< M3, or M1< M2= M3 or M1< M2< M3.

Therefore, in the display device provided in the embodiment of the present application, the guest materials with different mass percentages are doped in the electron transport layers of the three light emitting devices red, green, and blue, specifically, in the electron transport layers of the three light emitting devices red, green, and blue, the relationship between the mass percentages of the guest materials in the electron transport materials of the three light emitting devices is set as M1= M2< M3, or M1< M2= M3, or M1< M2< M3, so that the three light emitting devices red, green, and blue can respectively give consideration to the better device efficiency and lifetime at the same time, and further, the optimization of the respective performance of the three light emitting devices red, green, and blue is realized.

Further, the display device 100 provided in the embodiment of the present application further includes a substrate 10, a first electrode 20, a pixel defining layer 30, a hole injection layer 40, a hole transport layer 50, a light emitting layer 60, a second electrode 80, and an optical cover layer 90, which are sequentially disposed. The electron transport layer 70 is located between the light emitting layer 60 and the second electrode 80. The pixel defining layer 30 has a plurality of openings 30A. The opening 30A exposes the first electrode 20. The hole injection layer 40, the hole transport layer 50, the light emitting layer 60, and the electron transport layer 70 are all located within the opening 30A.

In the embodiment of the present application, the substrate 10 includes a substrate 11, a gate electrode G, a gate insulating layer 12, an active layer 13, source and drain electrodes S and D disposed on the active layer 13 at the same layer, an interlayer insulating layer 14, and a planarization layer 15, which are sequentially disposed.

The substrate 11 may be a glass, quartz, or transparent resin substrate. The gate G, the active layer 13, the source S, and the drain D constitute a pixel driving unit. The pixel driving unit includes a red light driving unit 101, a green light driving unit 102, and a blue light driving unit 103. The red driving unit 101 is located in the red sub-pixel region 10A. The green driving unit 102 is located at the green sub-pixel region 10B. The blue driving unit 103 is located in the blue sub-pixel region 10C.

In the present embodiment, the first electrode 20 may be an anode. The anode may have a single-layer structure, a double-layer structure, or a triple-layer structure. In this embodiment, the anode has a three-layer structure. The anode includes a first conductive layer 201, a second conductive layer 202, and a third conductive layer 203 which are sequentially provided.

The first conductive layer 201 is used to improve the interface characteristics with the substrate 10. The material of the first conductive layer 201 may be a transparent metal oxide, such as Indium Gallium Zinc Oxide (IGZO), indium Zinc Tin Oxide (IZTO), indium Gallium Zinc Tin Oxide (IGZTO), indium Tin Oxide (ITO), indium Zinc Oxide (IZO), indium Aluminum Zinc Oxide (IAZO), indium Gallium Tin Oxide (IGTO), or Antimony Tin Oxide (ATO), or Zinc Tin Oxide (ZTO), and the like.

The thickness of the first conductive layer 201 is 5nm to 30nm, and may be 5nm, 10nm, 15nm, 20nm, 25nm, or 30 nm. In some embodiments, the thickness of the first conductive layer 201 may be 10nm-20nm.

The second conductive layer 202 is used for reflecting light to improve the brightness and efficiency of the device. The second conductive layer 202 may be formed of a metal having an emissivity of 80% or more or an alloy thereof, such as aluminum (Al), silver (Ag), palladium (Pd), platinum (Pt), and aluminum-neodymium alloy (AlNd), silver-palladium-copper Alloy (APC), and the like.

The thickness of the second conductive layer 202 may be 80nm to 200nm, such as 80nm, 100nm, 120nm, 140nm, 150nm, 180nm, or 200nm. In some embodiments, the thickness of the second conductive layer 202 may be 140nm-150nm.

The third conductive layer 203 is used to improve optical characteristics. The material of the third conductive layer 203 may be a transparent metal oxide, such as Indium Gallium Zinc Oxide (IGZO), indium Zinc Tin Oxide (IZTO), indium Gallium Zinc Tin Oxide (IGZTO), indium Tin Oxide (ITO), indium Zinc Oxide (IZO), indium Aluminum Zinc Oxide (IAZO), indium Gallium Tin Oxide (IGTO), or Antimony Tin Oxide (ATO), or Zinc Tin Oxide (ZTO), and the like.

The thickness of the third conductive layer 203 may be 5nm to 100nm, such as 5nm, 10nm, 20nm, 50nm, 70nm, 80nm, or 100nm. In some embodiments, the thickness of third conductive layer 203 may be 10nm-20nm or 70nm-80nm.

The pixel defining layer 30 may be a single-layer structure or a double-layer structure. In the present embodiment, the pixel defining layer 30 has a single-layer structure. The thickness of the pixel defining layer 30 can be 0.5nm-2.5um, such as 0.5um, 1.0um, 1.5um, 2um or 2.5 um. In some embodiments, the thickness of the pixel defining layer 30 may be 1nm-1.5um.

The pixel defining layer 30 may be made of an organic photoresist material with a hydrophobic additive added thereto, or after the pixel defining layer 30 is formed by using the organic photoresist material, the surface of the pixel defining layer 30 is subjected to hydrophobic treatment. For example, a fluorine-containing additive is added to the organic photoresist material or a surface fluorination treatment is performed to enhance the hydrophobic property of the surface of the organic photoresist material.

The plurality of openings 30A on the pixel defining layer 30 include a plurality of first sub-openings 301, a plurality of second sub-openings 302, and a plurality of third sub-openings 303. The first sub-opening 301 corresponds to the red sub-pixel region 10A. The second sub-aperture 302 corresponds to the green sub-pixel region 10B. The third sub-opening 303 corresponds to the blue sub-pixel region 10C.

In the embodiment of the present application, the hole injection layer 40 includes a first sub-hole injection layer 401, a second sub-hole injection layer 402, and a third sub-hole injection layer 403. The first sub-hole injection layer 401 is located in the red sub-pixel region 10A. The second sub-hole injection layer 402 is located in the green sub-pixel region 10B. The third sub-hole injection layer 403 is located in the blue sub-pixel region 10C.

Specifically, the material of the hole injection layer 40 may be a conductive polymer material and a derivative thereof. The conductive polymer material may include polythiophene, polyaniline, or the like.

The thickness of the first sub-hole injection layer 401 is 40nm to 200nm, such as 40nm, 80nm, 110nm, 150nm, 180nm or 200nm. The thickness of the second sub hole injection layer 402 is 30nm to 100nm, and may be 30nm, 40nm, 50nm, 70nm, 80nm, or 100nm, for example. The thickness of the third sub hole injection layer 403 is 20nm to 60nm, and may be 20nm, 30nm, 40nm, 50nm, or 60nm, for example. In the present embodiment, the thickness of the first sub-hole injection layer 401 is 110nm. The thickness of the second sub hole injection layer 402 was 70nm. The thickness of the third sub-hole injection layer 403 was 40nm.

It should be noted that specific thicknesses of the first sub-hole injection layer 401, the second sub-hole injection layer 402, and the third sub-hole injection layer 403 may be selected according to device performance, and are not limited in this application.

In the embodiment of the present application, the hole transport layer 50 includes a first sub hole transport layer 501, a second sub hole transport layer 502, and a third sub hole transport layer 503. The first sub hole transport layer 501 is located in the red sub pixel region 10A. The second sub hole transport layer 502 is located in the green sub pixel region 10B. The third sub hole transport layer 503 is located in the blue sub pixel region 10C.

Specifically, the material of the hole transport layer 50 may be poly (9, 9-dioctylfluorene-CO-N- (4-butylphenyl) diphenylamine) (TFB), 3-hexyl-substituted polythiophene (P3 HT), poly (9-vinylcarbazole) (PVK), poly [ bis (4-phenyl) (4-butylphenyl) amine ] (poly-TPD), 4 '-tris (carbazol-9-yl) triphenylamine (TCTA), 4' -bis (9-Carbazole) Biphenyl (CBP), or the like.

The thicknesses of the first sub hole transporting layer 501, the second sub hole transporting layer 502 and the third sub hole transporting layer 503 are all 20nm to 120nm, such as 20nm, 40nm, 70nm, 90nm, 100nm or 120nm. In the present embodiment, the thickness of the first sub hole transport layer 501 is 90nm. The thickness of the second sub hole transport layer 502 was 90nm. The thickness of the third sub hole transporting layer 503 is 100nm.

It should be noted that specific thicknesses of the first sub hole transporting layer 501, the second sub hole transporting layer 502, and the third sub hole transporting layer 503 may be selected according to device performance, and are not limited in this application.

In the present embodiment, the light emitting layer 60 includes a red light emitting layer 601, a green light emitting layer 602, and a blue light emitting layer 603. The red light emitting layer 601 is located in the red sub-pixel region 10A. The green light emitting layer 602 is positioned in the green sub-pixel region 10B. The blue light emitting layer 603 is located in the blue sub-pixel region 10C.

The thicknesses of the red light emitting layer 601, the green light emitting layer 602 and the blue light emitting layer 603 are all 40nm to 80nm, such as 40nm, 50nm, 60nm, 70nm or 80nm. In this embodiment, the thickness of the red light emitting layer 601 is 60nm. The thickness of the green light emitting layer 602 was 70nm. The thickness of the blue light emitting layer 603 was 40nm.

It should be noted that the specific thicknesses of the red light emitting layer 601, the green light emitting layer 602, and the blue light emitting layer 603 may be selected according to device performance, and the application is not limited thereto. In addition, the material of the red light emitting layer 601, the material of the green light emitting layer 602, and the material of the blue light emitting layer 603 are all organic materials, and the selection of the specific materials can refer to the prior art, and will not be described herein.

In the embodiment of the present application, the electron transport layer 70 includes a first sub electron transport layer 701, a second sub electron transport layer 702, and a third sub electron transport layer 703. The first sub electron transport layer 701 is positioned in the red sub-pixel region 10A. The second sub electron transport layer 702 is located in the green sub-pixel region 10B. The third sub electron transport layer 703 is located in the blue sub-pixel region 10C.

Wherein the electron transport layer 70 comprises an electron transport material. The electron transport material includes a host material and a guest material. The types of host materials and guest materials in the first sub electron transport layer 701, the second sub electron transport layer 702, and the third sub electron transport layer 703 are the same, and the difference between the types of host materials and guest materials is that the doping ratios of the guest materials are different. Specifically, in the first sub electron transport layer 701, the mass percentage of the guest material in the electron transport material is M1. In the second sub electron transport layer 702, the mass percentage of the guest material in the electron transport material is M2. In the third sub electron transport layer 703, the mass percentage of the guest material in the electron transport material is M3. M1= M2< M3, or M1< M2= M3 or M1< M2< M3.

In the related art OLED device, the performance of the RGB three light emitting devices is different. For the red light emitting device and the green light emitting device, when the recombination region of the exciton is positioned at one side of the light emitting layer close to the hole transport layer, the red light emitting device and the green light emitting device have better performance; for a blue light emitting device, when the exciton recombination region is located on the side of the light emitting layer close to the electron transport layer, the performance of the blue light emitting device is better. However, when using the existing red, green and blue light emitting materials, the electron transmission rates of the red, green and blue light emitting devices are different greatly, for example, the electron transmission rate of the blue light emitting device is faster, while the electron transmission rate of the red light emitting device is relatively slower, so that it is often difficult to achieve the respective optimal performance of the red, green and blue light emitting devices under the same condition.

In this embodiment, by using electron transport materials with different doping ratios of guest materials in the red sub-pixel region 10A, the green sub-pixel region 10B, and the blue sub-pixel region 10C, specifically, in the red sub-pixel region 10A, the green sub-pixel region 10B, and the blue sub-pixel region 10C, the relationship among the mass percentages of the guest materials in the electron transport materials is set as M1= M2< M3, or M1< M2= M3 or M1< M2< M3, so that the performance difference of the three light emitting devices of red, green, and blue can be reduced, and the respective optimum performance of the three devices of red, green, and blue can be achieved.

In the red sub-pixel region 10A, the first electrode 20, the first sub-hole injection layer 401, the first sub-hole transport layer 501, the red light emitting layer 601, the first sub-electron transport layer 701, and the second electrode 80 form a red light emitting device R. In the green sub-pixel region 10B, the first electrode 20, the second sub-hole injection layer 402, the second sub-hole transport layer 502, the green light emitting layer 602, the second sub-electron transport layer 702, and the second electrode 80 constitute a green light emitting device G. In the blue sub-pixel region 10C, the first electrode 20, the third sub-hole injection layer 403, the third sub-hole transport layer 503, the blue light emitting layer 603, the third sub-electron transport layer 703, and the second electrode 80 constitute a blue light emitting device B.

Specifically, the method comprises the following steps:

first, since the electron transport rate of the blue light emitting device is significantly higher than that of the red light emitting device and the green light emitting device, and the exciton recombination zone of the blue light emitting device in the blue light emitting layer is far from the electron transport layer, the blue light emitting device cannot achieve better performance under the same conditions. Therefore, in this embodiment, M1= M2< M3, that is, the doping ratio of the guest material in the electron transport layer 70 of the red light emitting device R and the green light emitting device G is maintained to be the same, and by making the doping ratio of the guest material in the electron transport layer 70 of the blue light emitting device B larger than the doping ratio of the guest material in the red light emitting device R and the green light emitting device G, the electron transport rate of the blue light emitting device B is decreased compared to the red light emitting device R and the green light emitting device G, so that the exciton recombination zone of the blue light emitting device B in the blue light emitting layer 603 is closer to the electron transport layer 70, thereby improving the performance of the blue light emitting device B and reducing the performance difference between the blue light emitting device B and the red light emitting device R and the green light emitting device G.

Secondly, since the electron transport rate of the red light emitting device is lower than that of the green light emitting device, and the exciton recombination zone of the red light emitting device in the red light emitting layer is far away from the hole transport layer, the red light emitting device cannot achieve better performance under the same conditions. Therefore, in this embodiment, M1< M2= M3, that is, the doping ratio of the guest material in the electron transport layer 70 of the green light emitting device G and the blue light emitting device B is maintained to be the same, and the doping ratio of the guest material in the electron transport layer 70 of the red light emitting device R is smaller than the doping ratio of the guest material in the blue light emitting device B and the green light emitting device G, the electron transport rate of the red light emitting device R is increased compared to the blue light emitting device B and the green light emitting device G, so that the exciton recombination zone of the red light emitting device R in the red light emitting layer 601 is closer to the hole transport layer 50, the performance of the red light emitting device R is further increased, and the performance difference between the red light emitting device R and the blue light emitting device B and the green light emitting device G is reduced.

Thirdly, because the electron transmission rates of the blue light emitting device, the green light emitting device and the red light emitting device are sequentially reduced, the exciton recombination zone of the blue light emitting device in the blue light emitting layer is far away from the electron transmission layer, the exciton recombination zone of the red light emitting device in the red light emitting layer is far away from the hole transmission layer, the exciton recombination zone of the green light emitting device in the green light emitting layer is far away from the hole transmission layer, and the distance from the red light emitting device to the hole transmission layer is larger than that of the green light emitting device, the red, green and blue light emitting devices can not achieve better performance under the same condition. Therefore, in this embodiment, M1< M2< M3, that is, the doping ratio of the guest material in the electron transport layer 70 of the red light emitting device R, the green light emitting device G, and the blue light emitting device B is sequentially increased, so that the electron transport rates of the red light emitting device R, the green light emitting device G, and the blue light emitting device B are sequentially decreased, that is, the decrease degree of the electron transport rate in the blue light emitting device B is maximized, so that the exciton recombination zone of the blue light emitting device B in the blue light emitting layer 603 is closer to the electron transport layer 70, the exciton recombination zone of the red light emitting device R in the red light emitting layer 601 and the exciton recombination zone of the green light emitting device G in the green light emitting layer 602 are both closer to the hole transport layer 50, and the difference between the exciton recombination zone of the red light emitting device R in the red light emitting layer 601 and the hole transport layer 50 and the distance between the green light emitting device G in the light emitting layer 602 and the hole transport layer 50 is decreased, so that the respective performances of the red light emitting device R, the green light emitting device G, and the blue light emitting device B can be optimized.

In particular, M1 is 30% to 60%, such as may be 30%, 35%, 40%, 45%, 50%, 55% or 60%. M2 is 40% to 70%, such as may be 40%, 45%, 50%, 55%, 60%, 65% or 70%. M3 is 60% to 80%, such as may be 60%, 65%, 70%, 75% or 80%. In the examples of the present application, M1< M2< M3, M1 is 40%, M2 is 70%, and M3 is 80%.

The thicknesses of the first sub electron transport layer 701, the second sub electron transport layer 702, and the third sub electron transport layer 703 are the same, and are all 20nm to 50nm, such as 20nm, 30nm, 35nm, 45nm, or 45 nm. In the embodiment of the present application, the thicknesses of the first sub electron transport layer 701, the second sub electron transport layer 702, and the third sub electron transport layer 703 are all 25nm.

In some embodiments, the thicknesses of the first sub electron transport layer 701, the second sub electron transport layer 702, and the third sub electron transport layer 703 are sequentially increased. The arrangement can further reduce the performance difference among the red light emitting device R, the green light emitting device G and the blue light emitting device B, thereby being beneficial to improving the overall performance of the device.

The thickness of the first sub electron transport layer 701 is 20nm to 30nm, such as 20nm, 21nm, 22nm, 25nm, 28nm or 30 nm. The thickness of the second sub electron transport layer 702 is 30nm to 40nm, such as 30nm, 32nm, 34nm, 35nm, 38nm or 40nm. The thickness of the third sub electron transport layer 703 is 40nm to 50nm, and may be 40nm, 42nm, 44nm, 45nm, 47nm, or 50nm.

In the present embodiment, the second electrode 80 is a cathode. The cathode may have a single-layer structure or a double-layer structure. In this embodiment, the cathode has a double-layer structure. The cathode includes a fourth conductive layer 801 and a fifth conductive layer 802. The material of the fourth conductive layer 801 may be Yb or Ln, or the like. The material of the fifth conductive layer 802 may be one or more of Ag, al, or Mg/Ag.

The thickness of the fourth conductive layer 801 is 0.5nm to 10nm, such as 0.5nm, 0.75nm, 1nm, 5nm, or 10nm. The thickness of the fifth conductive layer 802 is 10nm to 100nm, such as 10nm, 20nm, 40nm, 50nm, 80nm, or 100nm.

In the embodiment of the present application, the optical coating 90 is disposed on the side of the second electrode 80 away from the substrate 10. Among them, the material of the optical cover layer 90 may be N, N '-di (1-naphthyl) -N, N' -diphenyl-1, 1 '-biphenyl-4-4' -diamine (NPB). The optical coating 90 has a thickness of 20nm to 200nm, such as 20nm, 40nm, 70nm, 120nm, 150nm or 200nm.

In the display device 100 provided in this embodiment, guest materials with different mass percentages are doped in the electron transport layer 70 of the red light emitting device R, the green light emitting device G, and the blue light emitting device B, specifically, in the electron transport layer 70 of the red light emitting device R, the green light emitting device G, and the blue light emitting device B, by setting the relationship among the mass percentages of the guest materials in the electron transport materials of the three to M1= M2< M3, or M1< M2= M3 or M1< M2< M3, the performance difference between the red light emitting device R, the green light emitting device G, and the blue light emitting device B can be reduced, and the red light emitting device R, the green light emitting device G, and the blue light emitting device B can give consideration to better device efficiency and lifetime at the same time, thereby realizing optimization of respective performances of the red light emitting device R, the green light emitting device G, and the blue light emitting device B.

Referring to fig. 2, an embodiment of the present application further provides a method for manufacturing a display device, which includes the following steps:

b1, providing an electron transport material to form an electron transport layer, wherein the electron transport material comprises a host material and a guest material;

the display device comprises a red sub-pixel area, a green sub-pixel area and a blue sub-pixel area, wherein the red sub-pixel area is provided with a mass percentage of the guest material in the electron transport material of M1, the green sub-pixel area is provided with a mass percentage of the guest material in the electron transport material of M2, and the blue sub-pixel area is provided with a mass percentage of the guest material in the electron transport material of M3, M1= M2< M3, or M1< M2= M3 or M1< M2< M3. In the embodiment of the present application, before the step of providing the electron transport material to form the electron transport layer, the method further includes: providing a substrate, and sequentially forming a first electrode, a pixel defining layer, a hole injection layer, a hole transport layer and a light emitting layer on the substrate, wherein the electron transport layer is formed on the light emitting layer. After the step of providing the electron transport material to form the electron transport layer, the method further comprises the following steps: and sequentially forming a second electrode and an optical covering layer on the electron transport layer.

Referring to fig. 3, a method for manufacturing the display device 100 according to the embodiment of the present application will be described in detail.

B11, providing a substrate 10.

The substrate 10 includes a substrate 11, a gate electrode G, a gate insulating layer 12, an active layer 13, source and drain electrodes S and D disposed on the active layer 13 at the same layer, an interlayer insulating layer 14, and a planarization layer 15, which are sequentially disposed.

The substrate 11 may be a glass, quartz, or transparent resin substrate 11. The gate G, the active layer 13, the source S, and the drain D constitute a pixel driving unit. The pixel driving unit includes a red driving unit 101, a green driving unit 102, and a blue driving unit 103.

The preparation method of the pixel driving unit can refer to the prior art, and is not described herein again.

And B12, forming a first electrode 20 on the substrate 10.

A first conductive layer 201, a second conductive layer 202, and a third conductive layer 203 are stacked on the substrate 10 in this order by a physical vapor deposition process and an etching process. The first conductive layer 201, the second conductive layer 202, and the third conductive layer 203 constitute a first electrode 20. In the present embodiment, the first electrode 20 is an anode.

The first conductive layer 201 is used to improve the interface characteristics with the substrate 10. The material of the first conductive layer 201 may be a transparent metal oxide such as Indium Gallium Zinc Oxide (IGZO), indium Zinc Tin Oxide (IZTO), indium Gallium Zinc Tin Oxide (IGZTO), indium Tin Oxide (ITO), indium Zinc Oxide (IZO), indium Aluminum Zinc Oxide (IAZO), indium Gallium Tin Oxide (IGTO), or Antimony Tin Oxide (ATO), or Zinc Tin Oxide (ZTO), or the like.

The third conductive layer 203 is used to improve optical characteristics. The material of the third conductive layer 203 may be a transparent metal oxide such as Indium Gallium Zinc Oxide (IGZO), indium Zinc Tin Oxide (IZTO), indium Gallium Zinc Tin Oxide (IGZTO), indium Tin Oxide (ITO), indium Zinc Oxide (IZO), indium Aluminum Zinc Oxide (IAZO), indium Gallium Tin Oxide (IGTO), or Antimony Tin Oxide (ATO), or Zinc Tin Oxide (ZTO), or the like.

B13, forming a pixel defining layer 30 on the first electrode 20, wherein a plurality of openings 30A are formed on the pixel defining layer 30, and the openings 30A expose the first electrode 20.

First, the pixel defining layer 30 is formed using a chemical vapor deposition process. The thickness of the pixel defining layer 30 can be 0.5nm-2.5um, such as 0.5um, 1.0um, 1.5um, 2um or 2.5 um. In some embodiments, the thickness of the pixel defining layer 30 may be 1nm-1.5um.

The pixel defining layer 30 may be made of an organic photoresist to which a hydrophobic additive is added, or after the pixel defining layer 30 is formed using an organic photoresist, the surface of the pixel defining layer 30 is subjected to a hydrophobic treatment. For example, a fluorine-containing additive is added to the organic photoresist material or a surface fluorination treatment is performed to enhance the hydrophobic property of the surface of the organic photoresist material.

Next, a plurality of openings 30A are formed on the pixel defining layer 30 by using a photolithography developing process. The plurality of openings 30A includes a plurality of first sub-openings 301, a plurality of second sub-openings 302, and a plurality of third sub-openings 303. The first sub-opening 301 defines a red sub-pixel region 10A. The second sub-opening 302 defines a green sub-pixel region 10B. The third sub-opening 303 defines a blue sub-pixel region 10C. The red driving unit 101 corresponds to the red sub-pixel region 10A. The green driving unit 102 corresponds to the green sub-pixel region 10B. The blue driving unit 103 corresponds to the blue sub-pixel region 10C.

B14, forming a hole injection layer 40, a hole transport layer 50 and a light emitting layer 60 on the pixel defining layer 30 in sequence, wherein the hole injection layer 40, the hole transport layer 50 and the light emitting layer 60 are all positioned in the opening 30A.

Specifically, B14 includes the following steps:

b141: hole injection ink is printed in the first sub-opening 301, the second sub-opening 302 and the third sub-opening 303, so that a first sub-hole injection layer 401 is formed in the first sub-opening 301, a second sub-hole injection layer 402 is formed in the second sub-opening 302, and a third sub-hole injection layer 403 is formed in the third sub-opening 303.

First, 40pL-200pL of hole injection ink was printed in the first sub-opening 301, 20pL-100pL of hole injection ink was printed in the second sub-opening 302, and 10pL-80pL of hole injection ink was printed in the third sub-opening 303.

Wherein the hole injection ink comprises a hole injection material and a solvent. The hole injection material may be a conductive polymer material and a derivative thereof. The conductive polymer material may include polythiophene or polyaniline. It should be noted that the solvent may be selected according to the type of the hole injection material, and is not described herein again.

In one embodiment, 80pL of hole injection ink is printed within the first sub-opening 301. A hole injection ink of 45pL is printed in the second sub-opening 302. A hole injection ink of 25pL is printed in the third sub-opening 303.

Then, after vacuum drying and high-temperature baking, a first sub-hole injection layer 401 with a thickness of 40nm to 200nm is formed in the first sub-opening 301, a second sub-hole injection layer 402 with a thickness of 30nm to 100nm is formed in the second sub-opening 302, and a third sub-hole injection layer 403 with a thickness of 20nm to 60nm is formed in the third sub-opening 303. The first sub hole injection layer 401, the second sub hole injection layer 402, and the third sub hole injection layer 403 constitute the hole injection layer 40. Wherein the high-temperature baking temperature is 100-300 ℃, and the baking time is 10-60 min.

In one embodiment, the high temperature baking temperature is 230 ℃ and the baking time is 30min. The thickness of the first sub-hole injection layer 401 is 110nm. The thickness of the second sub hole injection layer 402 was 70nm. The thickness of the third sub-hole injection layer 403 was 40nm.

B142: hole-transporting ink is printed in the first sub-opening 301, the second sub-opening 302 and the third sub-opening 303 to form a first sub-hole-transporting layer 501 in the first sub-opening 301, a second sub-hole-transporting layer 502 in the second sub-opening 302 and a third sub-hole-transporting layer 503 in the third sub-opening 303.

First, 40pL-100pL of hole transport ink is printed in the first sub-opening 301, 40pL-100pL of hole transport ink is printed in the second sub-opening 302, and 40pL-100pL of hole transport ink is printed in the third sub-opening 303, respectively.

In one embodiment, 64pL of hole transporting ink is printed within the first sub-opening 301. 64pL of hole transporting ink is printed within the second sub-opening 302. 68pL of hole transporting ink was printed within the third sub-opening 303.

The hole transport ink comprises a hole transport material and a solvent, and the hole transport material can be a conductive high molecular material and a derivative thereof. The conductive polymer material may be poly (9, 9-dioctylfluorene-CO-N- (4-butylphenyl) diphenylamine) (TFB), 3-hexyl-substituted polythiophene (P3 HT), poly (9-vinylcarbazole) (PVK), poly [ bis (4-phenyl) (4-butylphenyl) amine ] (poly-TPD), 4 '-tris (carbazol-9-yl) triphenylamine (TCTA), 4' -bis (9-Carbazole) Biphenyl (CBP), or the like. It should be noted that the solvent may be selected according to the type of the hole transport material, and is not described herein again.

Then, after vacuum drying and high-temperature baking, a first sub-hole transport layer 501 with a thickness of 20nm to 120nm is formed in the first sub-opening 301, a second sub-hole transport layer 502 with a thickness of 20nm to 120nm is formed in the second sub-opening 302, and a third sub-hole transport layer 503 with a thickness of 20nm to 120nm is formed in the third sub-opening 303. The first sub hole transport layer 501, the second sub hole transport layer 502, and the third sub hole transport layer 503 constitute the hole transport layer 50. Wherein the high-temperature baking temperature is 100-300 ℃, and the baking time is 10-60 min.

In one embodiment, the high temperature baking temperature is 230 ℃ and the baking time is 30min. The thickness of the first sub-hole transport layer 501 is 90nm. The thickness of the second sub hole transport layer 502 was 90nm. The thickness of the third sub hole transporting layer 503 is 100nm.

B143: organic light emitting ink is printed in the first sub-opening 301, the second sub-opening 302, and the third sub-opening 303 to form a red light emitting layer 601 in the first sub-opening 301, a green light emitting layer 602 in the second sub-opening 302, and a blue light emitting layer 603 in the third sub-opening 303.

First, 10pL-50pL of red light emitting ink, 20pL-100pL of green light emitting ink, and 20pL-100pL of blue light emitting ink are printed in the first sub-opening 301, the second sub-opening 302, and the third sub-opening 303, respectively.

The red light-emitting ink comprises a red light-emitting material and a first solvent, the green light-emitting ink comprises a green light-emitting material and a second solvent, and the blue light-emitting ink comprises a blue light-emitting material and a third solvent. It should be noted that the types of the red light emitting material, the green light emitting material, and the blue light emitting material may all refer to the prior art, and accordingly, the first solvent, the second solvent, and the third solvent are respectively selected according to the types of the corresponding light emitting materials, which is not described herein again.

In one embodiment, 26pL of red-emitting ink is printed within the first sub-opening 301. 50pL of green luminescent ink was printed in the second sub-opening 302. Within the third sub-opening 303, 45pL of blue light emitting ink is printed.

Then, after vacuum drying and high-temperature baking, a red light emitting layer 601 with a thickness of 40nm to 80nm is formed in the first sub-opening 301, a green light emitting layer 602 with a thickness of 40nm to 80nm is formed in the second sub-opening 302, and a blue light emitting layer 603 with a thickness of 40nm to 80nm is formed in the third sub-opening 303. The red light emitting layer 601, the green light emitting layer 602, and the blue light emitting layer 603 constitute the light emitting layer 60. Wherein the high-temperature baking temperature is 100-300 ℃, and the baking time is 10-60 min.

In one embodiment, the high temperature baking temperature is 140 ℃ and the baking time is 30min. The thickness of the red light emitting layer 601 is 60nm. The thickness of the green light emitting layer 602 was 70nm. The thickness of the blue light emitting layer 603 was 40nm.

B15, providing an electron transport material, and forming an electron transport layer 70 on the light-emitting layer 60, wherein the electron transport material is composed of a host material and a guest material; in the red sub-pixel region 10A, the mass percentage of the guest material in the electron transport material is M1, in the green sub-pixel region 10B, the mass percentage of the guest material in the electron transport material is M2, and in the blue sub-pixel region 10C, the mass percentage of the guest material in the electron transport material is M3, M1= M2< M3, or M1< M2= M3 or M1< M2< M3.

The electron transport material in the red sub-pixel region 10A is defined as a first electron transport material, and the mass percentage of the guest material in the first electron transport material is M1. The electron transport material in the green sub-pixel region 10B is defined as a second electron transport material, and the mass percentage of the guest material in the second electron transport material is M2. The electron transport material in the blue sub-pixel region 10C is defined as a third electron transport material, and the mass percentage of the guest material in the third electron transport material is M3.

First, a first electron transfer ink of 20pL-100pL is printed in the first sub opening 301, a second electron transfer ink of 20pL-100pL is printed in the second sub opening 302, and a third electron transfer ink of 20pL-100pL is printed in the third sub opening 303.

Wherein the first electron-transporting ink includes a first electron-transporting material and a solvent. The second electron transport ink includes a second electron transport material and a solvent. The third electron transporting ink includes a third electron transporting material and a solvent. The first electron transport material, the second electron transport material and the third electron transport material are all composed of the same host material and the same guest material. The host material is selected from at least one of 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene, 1, 3-bis [5- (4-tert-butylphenyl) -2- [1,3,4] oxadiazolyl ] benzene, tris (2, 4, 6-trimethyl-3- (pyridin-3-yl) phenyl) borane, 1,3, 5-tris [ (3-pyridyl) -3-phenyl ] benzene, 1,3, 5-tris (diphenyl-phosphoryl-phen-3-yl) benzene, 2, 7-bis (diphenylphosphinyl) -9,9 '-spirobifluorene, poly [ (9, 9-bis (3' - ((N, N-dimethyl) -N-ethylammonium) -propyl) -2, 7-fluorene) -ALT-2,7- (9, 9-dioctylfluorene) ] -dibromo. The guest material is at least one selected from 8-hydroxyquinoline lithium, 8-hydroxyquinoline sodium, 8-hydroxyquinoline cesium, phenol-based pyridine lithium, lithium acetate, sodium acetate, cesium acetate, lithium carbonate and cesium carbonate. In a specific embodiment, the host material is 1,3, 5-tris (diphenyl-phosphoryl-phen-3-yl) benzene. The guest material is 8-hydroxyquinoline lithium. 45pL of the first electron transport ink is printed within the first sub-opening 301. A 45pL second electron transfer ink is printed within the second sub-opening 302. A third electron transfer ink of 35pL is printed within the third sub-opening 303.

Then, after vacuum drying and high-temperature baking, the first electron transport ink forms a first sub electron transport layer 701 with a thickness of 20nm to 50nm in the first sub opening 301; within the second sub-opening 302, the second electron transporting ink forms a second sub-electron transporting layer 702 having a thickness of 20nm to 50nm; within the third sub opening 303, the third electron transport ink forms a third sub electron transport layer 703 having a thickness of 20nm to 50nm. The first sub electron transport layer 701, the second sub electron transport layer 702, and the third sub electron transport layer 703 constitute the electron transport layer 70. Wherein the high-temperature baking temperature is 100-300 ℃, and the baking time is 10-60 min.

In one embodiment, the high temperature bake temperature is 140 ℃. The baking time is 30min. The thicknesses of the first sub electron transport layer 701, the second sub electron transport layer 702, and the third sub electron transport layer 703 are all 25nm.

In addition, in the first sub electron transport layer 701, M1 is between 30% and 60%; in the second sub electron transport layer 702, M2 is between 40% and 70%; in the third sub electron transport layer 703, M3 is between 60% and 80%. In this embodiment, M1< M2< M3, specifically, M1 is 40%, M2 is 70%, and M3 is 80%.

B16, forming a second electrode 80 and an optical coating layer 90 on the electron transport layer 70 in this order.

A fourth conductive layer 801, a fifth conductive layer 802, and an optical cover layer 90 are sequentially formed on the electron transit layer 70 by a vacuum evaporation process.

Wherein the fourth conductive layer 801 and the fifth conductive layer 802 form the second electrode 80. The second electrode 80 is a cathode. The material of the fourth conductive layer 801 may be Yb or Ln, or the like. The thickness of the fourth conductive layer 801 is 0.5nm to 10nm. The material of the fifth conductive layer 802 may be one or more of Ag, al, or Mg/Ag. The thickness of the fifth conductive layer 802 is 10nm to 100nm.

In one embodiment, the thickness of the fourth conductive layer 801 is 1nm. The thickness of the fifth conductive layer 802 is 20nm.

Among them, the material of the optical coating layer 90 may be N, N '-bis (1-naphthyl) -N, N' -diphenyl-1, 1 '-biphenyl-4-4' -diamine (NPB). The optical coating 90 has a thickness of 20nm to 200nm.

In one embodiment, the material of the optical coating 90 is 70nm.

Examples 1 and comparative examples 1 to 3 are provided below, and the performance of the red light emitting device R, the green light emitting device G, and the blue light emitting device B in the display device corresponding to each of examples 1 and comparative examples 1 to 3 was measured. The method comprises the following specific steps:

example 1

The method for manufacturing the display device provided in embodiment 1 includes the steps of:

(1) A stacked structure of a first conductive layer 201, a second conductive layer 202, and a third conductive layer 203 is formed over the substrate 10, and the stacked structure constitutes an anode. The first conductive layer 201 is made of ITO and has a thickness of 15nm; the second conductive layer 202 is made of Ag and has a thickness of 150nm; the material of the third conductive layer 203 is ITO, and the thickness is 80nm.

(2) An ink-repellent fluorine-containing resin is used as a material, a pixel defining layer 30 with the thickness of 1.5um is formed on the anode by adopting a physical vapor deposition process, and patterning processing is carried out on the pixel defining layer 30 through an exposure and development process, so that a first sub-opening 301, a second sub-opening 302 and a third sub-opening 303 which expose the anode are formed on the pixel defining layer 30.

(3) The method comprises the steps of using poly 3, 4-ethylenedioxythiophene/polystyrene sulfonate (PEDOT: PSS) as a hole injection material, respectively printing 80pL, 45pL and 25pL hole injection inks in a first sub-opening 301, a second sub-opening 302 and a third sub-opening 303, drying in vacuum and baking at 230 ℃ for 30min, forming a first sub-hole injection layer 401 with the thickness of 110nm in the first sub-opening 301, forming a second sub-hole injection layer 402 with the thickness of 70nm in the second sub-opening 302, and forming a third sub-hole injection layer 403 with the thickness of 40nm in the third sub-opening 303.

(4) Using TFB as a hole transport material, printing hole transport inks of 64pL, 64pL and 68pL in the first sub-opening 301, the second sub-openings 302 and the third sub-opening 303 respectively, and after vacuum drying and high-temperature baking at 230 ℃ for 30min, forming a first sub-hole transport layer 501 with a thickness of 90nm in the first sub-opening 301, a second sub-hole transport layer 502 with a thickness of 90nm in the second sub-opening 302 and a third sub-hole transport layer 503 with a thickness of 110nm in the third sub-opening 303.

(5) 26pL of red light-emitting material, 50pL of green light-emitting material and 45pL of blue light-emitting material are respectively printed in the first sub-opening 301, the second sub-opening 302 and the third sub-opening 303, and after vacuum drying and high-temperature baking at 140 ℃ for 30min, a red light-emitting layer 601 with the thickness of 60nm is formed in the first sub-opening 301, a green light-emitting layer 602 with the thickness of 70nm is formed in the second sub-opening 302, and a blue light-emitting layer 603 with the thickness of 40nm is formed in the third sub-opening 303.

(6) The electron transport layer 70 is formed on the light emitting layer 60 using an inkjet printing process. Specifically, 45pL of first electron transport ink, 40pL of second electron transport ink, and 35pL of third electron transport ink are printed in the first sub-opening 301, the second sub-opening 302, and the third sub-opening 303, respectively, and after vacuum drying and baking at 120 ℃ for 20min, a first sub-electron transport layer 701, a second sub-electron transport layer 702, and a third sub-electron transport layer 703 are formed in the first sub-opening 301, the second sub-opening 302, and the third sub-opening 303, and the first sub-electron transport layer 701, the second sub-electron transport layer 702, and the third sub-electron transport layer 703 constitute the electron transport layer 70. The host materials and the guest materials in the first electron transport layer 701, the second electron transport layer 702 and the third electron transport layer 703 are the same, the host materials are all 1,3, 5-tris (diphenyl-phosphoryl-phen-3-yl) benzene, the guest materials are all 8-hydroxyquinolinate lithium, M1 is 40%, M2 is 70%, and M3 is 80%. The thicknesses of the first sub electron transport layer 701, the second sub electron transport layer 702, and the third sub electron transport layer 703 are all 25nm.

(7) Evaporating Yb on the electron transport layer 70 to form a fourth conductive layer 801 with a thickness of 1 nm; then, ag was deposited on the fourth conductive layer 801 to form a fifth conductive layer 802 having a thickness of 20nm, and the fourth conductive layer 801 and the fifth conductive layer 802 constituted a cathode.

(8) NPB was vapor deposited on the cathode to form an optical coating 90 having a thickness of 70nm.

Among them, in embodiment 1, in the first sub opening 301, the anode, the first sub hole injection layer 401, the first sub hole transport layer 501, the red light emitting layer 601, the first sub electron transport layer 701, and the cathode constitute the red light emitting device R; in the second sub opening 302, the anode, the second sub hole injection layer 402, the second sub hole transport layer 502, the green light emitting layer 602, the second sub electron transport layer 702, and the cathode constitute a green light emitting device G; in the third sub opening 303, the anode, the third sub hole injection layer 403, the third sub hole transport layer 503, the blue light emitting layer 603, the third sub electron transport layer 703 and the cathode constitute a blue light emitting device B.

Comparative example 1

Comparative example 1 provides a display device different from example 1 in that: in the red light emitting device R, the green light emitting device G, and the blue light emitting device B, the mass percentages of the guest materials in the electron transport material in the first sub electron transport layer 701, the second sub electron transport layer 702, and the third sub electron transport layer 703 are the same, and are all 40%.

Comparative example 2

Comparative example 2 provides a display device different from example 1 in that: in the red light emitting device R, the green light emitting device G, and the blue light emitting device B, the mass percentages of the guest materials in the electron transport material in the first electron transport layer 701, the second electron transport layer 702, and the third electron transport layer 703 are the same, and are all 70%.

Comparative example 3

The display device provided in comparative example 3 is different from that of example 1 in that the guest materials in the first, second, and third sub

electron transport layers

701, 702, and 703 are the same in mass% in the electron transport material in the red, green, and blue light emitting devices R, G, and B, all of which are 80%.

The red light emitting device R, the green light emitting device G, and the blue light emitting device B in the display devices of example 1 and comparative examples 1 to 3 were each determined to have the same luminance (1000 cd/m) by experiment ² ) The current density, voltage, current efficiency and life time relative values are shown in table 1 below. The spectral colors corresponding to the red light emitting device R, the green light emitting device G and the blue light emitting device B are red light, green light and blue light, respectively. The calculation method of the life relative value is as follows: the percentage of life of comparative examples 1-3 compared to example 1 was determined based on example 1.

TABLE 1

As can be seen from comparative analysis, in comparative examples 1 to 3: with the increase of the doping ratio of the guest material in the electron transport material of the red light emitting device R in the display devices of comparative example 1, comparative example 2, and comparative example 3 (the mass percentages of the three are 40%, 70%, and 80% in order), the life of the corresponding light emitting device becomes better, but the voltage increases and the current efficiency decreases; with the increase of the doping ratio of the guest material in the electron transport material of the green light emitting device G in the display devices of comparative example 1, comparative example 2, and comparative example 3 (the mass percentages of the three are 40%, 70%, and 80% in order), the life of the corresponding light emitting device becomes good, but the voltage increases, and the current efficiency decreases; as the doping ratio of the guest material in the electron transport material of the blue light emitting device B in the display devices of comparative example 1, comparative example 2, and comparative example 3 increases (40%, 70%, and 80% by mass in this order), the life of the corresponding light emitting device becomes good, but the voltage increases and the current efficiency decreases. Therefore, the red light emitting device R, the green light emitting device G and the blue light emitting device B cannot simultaneously give consideration to better device efficiency and service life.

In embodiment 1, the electron transport layer 70 is prepared by using an inkjet printing process, and since the doping ratio of the guest material in the electron transport material of the red light emitting device R, the green light emitting device G, and the blue light emitting device B is gradually increased, and in the electron transport layer 70, when the doping percentage of the guest material in the electron transport material of the red light emitting device R is 40%, the doping percentage of the guest material in the electron transport material of the green light emitting device G is 70%, and the doping percentage of the guest material in the electron transport material of the blue light emitting device B is 80%, the respective device efficiencies and lifetimes of the red light emitting device R, the green light emitting device G, and the blue light emitting device B can maintain a good balance value. As shown in table 1, at the above doping ratio, the current efficiency of the red light emitting device R is 28cd/a, the lifetime relative value is 100%, the current efficiency of the green light emitting device G is 97cd/a, the lifetime relative value is 100%, the current efficiency of the blue light emitting device B is 3.2cd/a, and the lifetime relative value is 100%, so that the red light emitting device R, the green light emitting device G, and the blue light emitting device B can achieve the optimization of their respective performances in the display device prepared in example 1.

The above detailed description is provided for the electron transport material, the display device and the method for manufacturing the display device provided in the embodiments of the present application, and the principle and the implementation manner of the present application are explained in the present application by applying specific examples, and the description of the above embodiments is only used to help understanding the method and the core concept of the present application; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manner and the application scope may be changed, and in summary, the content of the present specification should not be construed as a limitation to the present application.

Claims

1. An electron transport material, comprising a host material and a guest material;

2. The electron transport material of claim 1, wherein M1 is between 30% and 60%, M2 is between 40% and 70%, M3 is between 60% and 80%,

still preferably, the guest material is at least one selected from the group consisting of lithium 8-quinolinolato, sodium 8-quinolinolato, cesium 8-quinolinolato, lithium phenolpyridinato, lithium acetate, sodium acetate, cesium acetate, lithium carbonate, and cesium carbonate.

3. A display device having a red sub-pixel region, a green sub-pixel region, and a blue sub-pixel region, the display device comprising an electron transport layer comprising an electron transport material, the electron transport material comprising a host material and a guest material;

4. A display device as claimed in claim 3, characterized in that M1 is between 30% and 60%, M2 is between 40% and 70%, and M3 is between 60% and 80%.

5. The display device according to claim 3, wherein the electron transport layer comprises a first sub electron transport layer, a second sub electron transport layer, and a third sub electron transport layer, the first sub electron transport layer is located in the red sub-pixel region, the second sub electron transport layer is located in the green sub-pixel region, the third sub electron transport layer is located in the blue sub-pixel region, and thicknesses of the first sub electron transport layer, the second sub electron transport layer, and the third sub electron transport layer are sequentially increased.

6. The display device according to claim 5, wherein the first sub electron transport layer has a thickness of 20nm to 30nm, the second sub electron transport layer has a thickness of 30nm to 40nm, and the third sub electron transport layer has a thickness of 40nm to 50nm.

7. The display device according to claim 3, wherein the host material is selected from at least one of 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene, 1, 3-bis [5- (4-tert-butylphenyl) -2- [1,3,4] oxadiazolyl ] benzene, tris (2, 4, 6-trimethyl-3- (pyridin-3-yl) phenyl) borane, 1,3, 5-tris [ (3-pyridyl) -3-phenyl ] benzene, 1,3, 5-tris (diphenyl-phosphoryl-phen-3-yl) benzene, 2, 7-bis (diphenylphosphino) -9,9 '-spirobifluorene, poly [ (9, 9-bis (3' - ((N, N-dimethyl) -N-ethylammonium) -propyl) -2, 7-fluorene) -ALT-2,7- (9, 9-dioctylfluorene) ] -dibromide,

8. A method for manufacturing a display device, comprising the steps of:

9. The electron transport material of claim 8, wherein M1 is between 30% and 60%, M2 is between 40% and 70%, M3 is between 60% and 80%,