CN109950415B

CN109950415B - Top-emitting light-emitting device and preparation method thereof

Info

Publication number: CN109950415B
Application number: CN201910129410.9A
Authority: CN
Inventors: 顾辛艳
Original assignee: Najing Technology Corp Ltd
Current assignee: Najing Technology Corp Ltd
Priority date: 2019-02-21
Filing date: 2019-02-21
Publication date: 2021-07-27
Anticipated expiration: 2039-02-21
Also published as: CN109950415A

Abstract

The invention discloses a top-emitting light-emitting device and a preparation method thereof. The top emission light emitting device includes: a substrate; a pixel defining structure disposed over the substrate for defining a plurality of light emitting areas; the light-emitting units are arranged in the light-emitting areas, share a top electrode, extend outwards from the light-emitting areas and cover the top surfaces of the pixel defining structures; the light extraction units are arranged in the light emitting areas and are arranged on the light emitting sides of the light emitting units; and the auxiliary electrode is arranged above the top surface of the pixel defining structure, and is electrically connected with the top electrode. The auxiliary electrode is arranged on the top electrode, so that the problem of insufficient conductivity of the top electrode is solved, the preparation method of the auxiliary electrode is simple, and the top electrode cannot be damaged; the light extraction unit is arranged on the light extraction side of the light emitting unit, so that the light extraction rate of the light emitting device can be improved.

Description

Top-emitting light-emitting device and preparation method thereof

Technical Field

The invention relates to the technical field of light-emitting devices, in particular to a top-emitting light-emitting device and a preparation method thereof.

Background

The self-luminous display technology of Organic Light Emitting Diode (OLED) is getting more and more attention due to its advantages of fast response and high contrast, however, the material utilization rate is low, the physical vapor deposition equipment is expensive and consumes high energy, so that the price of the OLED panel is high, people generally aim at quantum dot light emitting diode (QLED) with narrow half-peak width, wider color gamut and solution process, and the material utilization rate is greatly increased and the equipment cost is obviously reduced due to the adoption of the on-demand ink-jet printing technology to manufacture each layer of the device, so that the self-luminous display technology of Organic Light Emitting Diode (OLED) is considered as a powerful competitor of OLED. However, both OLED and QLED have a problem of low light extraction efficiency. It is believed that only about 20% of the energy generated by the light emitting device is ultimately captured by the human eye, a significant amount of light is dissipated within the device, and the efficiency and lifetime of the device are greatly affected.

In order to improve the light emitting of the device and prolong the service life, the light emitting mode of the device can be changed to increase the aperture opening ratio, namely, top emission is used for replacing bottom emission, as the light path of the top emission device is not influenced by TFT wiring, the aperture opening ratio of a pixel can be greatly improved, namely, the pixel area is increased, and the current density driven by the device can be reduced, thereby effectively prolonging the service life of the device. However, the top electrode has insufficient conductivity, and especially when a large-area display device is manufactured, the device often emits uneven light due to large voltage drop.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a top emission device and a preparation method thereof, which can ensure the conductivity of a top electrode, obtain good light-emitting uniformity and inhibit mutual optical crosstalk of adjacent sub-pixels.

According to an aspect of the present invention, there is provided a top emission light emitting device including: a substrate; a pixel defining structure disposed over the substrate for defining a plurality of light emitting areas; the top electrode extends outwards from the inside of each light-emitting area and covers the top surface of the pixel defining structure; the top-emitting light-emitting device further comprises

The light extraction units are arranged in the light emitting areas and are arranged on the light emitting sides of the light emitting units; and

an auxiliary electrode disposed above the pixel defining structure top surface, and the auxiliary electrode is conductively connected with the top electrode.

Further, the pixel defining structure is a mesh structure.

Furthermore, the surface tension of the upper surface of the light extraction unit is 25-40 dyne/cm, and the surface tension of the top electrode is greater than that of the upper surface of the light extraction unit.

Further, the light extraction unit includes scattering particles and a continuous phase resin that confines the scattering particles in the light emitting region.

Further, the light extraction unit comprises at least one layer comprising the scattering particles, the light extraction unit optionally comprising a layer not provided with scattering particles.

Further, the equivalent refractive index of the light extraction unit is 1.5-2.5.

Further, the top surface of the light extraction unit is a plane or an arc surface with a convex middle part, the edge of the top surface of the light extraction unit is not higher than the bottom surface of the auxiliary electrode with the substrate as a reference, and the highest point of the top surface of the light extraction unit is not higher than the highest point of the auxiliary electrode.

Further, a protective layer is arranged between the top electrode corresponding to the light emitting unit and the light extraction unit; preferably, the thickness of the protective layer is 40-400 nm.

According to another aspect of the present invention, there is provided a method of manufacturing a top emission light emitting device, including the steps of:

s1, providing a substrate with a bottom electrode, wherein a pixel defining structure for defining a plurality of light emitting areas is arranged on the substrate;

s2, disposing a top electrode in each of the light-emitting areas and on the surface of the pixel defining structure;

s3, forming light extraction units in each of the light emitting regions;

s4, an auxiliary electrode is disposed over the top surface of the pixel defining structure, the auxiliary electrode being conductively connected to the top electrode.

Further, in step S4, the auxiliary electrode is formed by drying or curing the conductive ink.

Furthermore, a spacing unit is arranged between the light extraction units, the surface energy of the upper surface of the spacing unit is greater than that of the upper surface of the adjacent light extraction unit, conductive ink is arranged on the upper surface of the spacing unit and/or the light extraction unit, the conductive ink is enriched to the upper surface corresponding to the top surface of the pixel defining structure, and the auxiliary electrode is formed after the conductive ink is dried or cured.

Further, the surface tension of the conductive ink is 25-40 dyne/cm, and the surface tension of the upper surface of the light extraction unit is 25-40 dyne/cm.

Further, the conductive ink comprises a conductive component, a solvent and a modification stabilizer; preferably, the conductive component is selected from one or more of the following: metal nanowires, metal nanoparticles, graphene, carbon nanotubes; preferably, the mass fraction of the conductive component in the conductive ink is 1-55%.

Further, between the step S2 and the step S3, there is a step of: arranging a protective layer in each light-emitting area, wherein the protective layer covers the surface of the top electrode in the light-emitting area; in step S3, disposing the light extraction unit on the protective layer in the light emitting region; in step S4, the conductive ink is disposed on the exposed surface of the top electrode, and the conductive ink is dried or cured to form the auxiliary electrode.

Further, between the step S2 and the step S3, there is a step of: arranging a protective layer on the surface of the top electrode, wherein the material of the protective layer comprises an organic material, and the organic material is soluble in the conductive ink; in step S3, providing a light extraction unit on the protective layer in the light emitting region; in the step S4, the conductive ink is disposed on the surface of the exposed protective layer, the conductive ink dissolves the organic material of the protective layer, and the conductive ink is dried or cured to form the auxiliary electrode.

Further, between the step S2 and the step S3, there is a step of: arranging a protective layer on the surface of the top electrode, wherein the material of the protective layer comprises a conductive material; in step S3, providing a light extraction unit on the protective layer in the light emitting region; in the step S4, the conductive ink is disposed on the surface of the exposed protective layer, and the conductive ink and the protective layer form the auxiliary electrode together after being dried or cured.

Further, the conductive material is selected from one or more of a metal, a metal oxide or a metal nitride.

Compared with the prior art, the invention has the beneficial effects that: the auxiliary electrode is arranged on the top electrode, so that the problem of insufficient conductivity of the top electrode is solved, the preparation method of the auxiliary electrode is simple, and the top electrode cannot be damaged; the light extraction units are arranged on the light extraction side of the light emitting units, so that the light extraction rate of the light emitting device can be improved, and the auxiliary electrodes arranged between the light emitting areas can play a role in isolating the light extraction units, so that light mixing between the adjacent light extraction units can be effectively avoided.

Drawings

FIG. 1 is a schematic cross-sectional view of one embodiment of a top-emitting light-emitting device of the present invention;

FIG. 2 is a schematic cross-sectional view of another embodiment of a top-emitting light-emitting device of the present invention;

FIG. 3 is a top view of one embodiment of a top-emitting light-emitting device of the present invention;

FIG. 4 shows a substrate and a pixel definition structure disposed on the substrate when the top-emitting light-emitting device of the present invention is fabricated;

FIG. 5 shows one embodiment of the fabrication of the light emitting layer of the top-emitting light emitting device of the present invention;

FIG. 6 shows one embodiment of top electrode fabrication of a top-emitting light-emitting device of the present invention;

fig. 7 shows one embodiment of the preparation of a light extraction unit of a top-emission light-emitting device of the present invention;

FIG. 8 shows one embodiment of the fabrication of a protective layer for a top-emitting light-emitting device of the present invention;

fig. 9 shows one embodiment of the preparation of a light extraction unit of the top-emission light-emitting device of the present invention;

FIG. 10 shows one embodiment of the preparation of the auxiliary electrode of the top-emission light-emitting device of the present invention;

FIG. 11 shows one embodiment of the preparation of the auxiliary electrode of the top-emission light-emitting device of the present invention;

FIG. 12 shows one embodiment of the preparation of a protective layer for a top-emitting light-emitting device of the present invention;

fig. 13 shows one embodiment of the preparation of a light extraction unit of a top-emission light-emitting device of the present invention;

FIG. 14 shows one embodiment of the preparation of an auxiliary electrode of a top-emission light-emitting device of the present invention;

FIG. 15 shows one embodiment of the preparation of an auxiliary electrode of a top-emission light-emitting device of the present invention;

FIG. 16 shows one embodiment of the preparation of an auxiliary electrode of a top-emission light-emitting device of the present invention;

fig. 17 shows an example of preparation of a light extraction unit of a top-emission light-emitting device of the present invention;

FIG. 18 shows one embodiment of the preparation of an auxiliary electrode of a top-emission light-emitting device of the present invention;

FIG. 19 shows one embodiment of the preparation of an auxiliary electrode of a top-emission light-emitting device of the present invention;

in the figure: 1. a substrate; 2. a pixel defining structure; 20. a light emitting region; 3. a light emitting unit; 31. a light emitting layer; 32. a top electrode; 4. a light extraction unit; 41. scattering particles; 42. a resin; 421. a first layer of resin; 422. a second layer of resin; 5. an auxiliary electrode; 50. a conductive ink; 6. a protective layer; 60. an organic material.

Detailed Description

The present invention is further described below with reference to specific embodiments, and it should be noted that, without conflict, any combination between the embodiments or technical features described below may form a new embodiment.

In the description of the present invention, it should be noted that, for the terms of orientation, such as "central", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., it indicates that the orientation and positional relationship shown in the drawings are based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, but does not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated without limiting the specific scope of protection of the present invention.

It is noted that the terms first, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the application described herein may be used. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

As shown in fig. 1, 2 and 3, the present invention provides a top emission light emitting device including a substrate 1, a pixel defining structure 2, a plurality of light emitting cells 3, a plurality of light extraction cells 4 and an auxiliary electrode 5.

The pixel defining structure 2 is disposed above the substrate 1 and is used for defining a plurality of light emitting regions 20, such that the light emitting regions 20 are isolated from each other, as shown in fig. 4. The pixel defining structure 2 is prior art and the invention is not limited to its specific structure. The pixel defining structure 2 may be formed on the substrate 1 by printing or etching, and the material of the pixel defining structure 2 may be one or a combination of inorganic materials and polymer materials. Various pixel definition structures that can be conceived by those skilled in the art in conjunction with the prior art are within the scope of the present invention.

The light-emitting units 3 comprise a bottom electrode, a light-emitting layer 31 and a top electrode 32, which are sequentially disposed, wherein the bottom electrode is disposed on the substrate 1, the light-emitting layer 31 is disposed in the light-emitting areas 20, each light-emitting unit 3 shares one top electrode 32, that is, the top electrodes 32 of the light-emitting units 3 are connected to form a whole, and the top electrodes 32 extend outwards from the light-emitting areas 20 and cover the top surfaces of the pixel defining structures 2. The top electrode 32 has a light transmittance to allow light emitted from the light emitting layer 31 to at least partially pass through the top electrode 32.

The light extraction units 4 are respectively disposed in the light emitting regions 20, and the light extraction units 4 are disposed on the light emitting side of the light emitting unit 3 for collecting light emitted from the light emitting unit 3 to improve the light emitting efficiency.

The auxiliary electrode 5 is disposed above the top surface of the pixel defining structure 2, and the auxiliary electrode 5 is electrically conductively connected with the top electrode 32. It should be noted that the term "top surface of the pixel defining structure 2" as used herein refers to the upper end surface of the pixel defining structure 2 on the side away from the substrate 1, and the top surface of the pixel defining structure 2 is located between the light emitting regions 20. The phrase "above the top surface of the pixel defining structure 2" in the present invention may refer to the surface of the portion of the top electrode 32 covering the top surface of the pixel defining structure 2, i.e., the surface of the portion of the top electrode 32 outside the light emitting region 20; it is also possible to add further layers on the top electrode 32 covering the top surface of the pixel defining structure 2, and "above" the top surface of the pixel defining structure 2 refers to the surface of the further layers covering the top electrode corresponding to the top surface of the pixel defining structure 2.

The top emission light emitting device of the present invention adds the auxiliary electrode 5 above the top surface of the pixel defining structure 2, which can solve the problem of insufficient conductivity of the top electrode 32; a light extraction unit 4 is arranged in the light extraction direction of each light-emitting unit 3, so that the light extraction performance of the device can be improved; in addition, the light extraction units 4 are disposed in the light-emitting regions 20 defined by the pixel defining structure 2, and the auxiliary electrodes 5 are disposed between the light-emitting regions 20, so that the auxiliary electrodes 5 also have a function of isolating the light extraction units 4 from each other, thereby effectively preventing the occurrence of light mixing between the adjacent light extraction units 4.

In some embodiments, the height of the pixel defining structure 2 is 1-2 μm. The sum of the thicknesses of the top electrode 32 and the layers excluding the bottom electrode in the light-emitting unit 3 is 150 to 350 nm. The thickness of the light extraction unit 4 is not less than 0.3 μm. The "thickness" as used herein means the length in the direction perpendicular to the substrate 1.

The light emitting layer 31 may be, but is not limited to, an organic light emitting layer, a quantum dot light emitting layer.

The material of the top electrode 32 may be metal (e.g., Au, Ag, Al), metal oxide (e.g., ITO, IZO, Zn (Al) O), or a stacked structure of a metal layer and a metal oxide layer (e.g., ITO/Al/ITO), and the top electrode 32 may be formed by evaporation or sputtering. The above examples of the material and the manufacturing process of the top electrode 32 are not exhaustive, and those skilled in the art can easily understand the material and the manufacturing process of the top electrode 32 in combination with the prior art and are within the scope of the present invention. Preferably, the light transmittance of the top electrode 32 is not less than 30%.

The bottom electrode is preferably a reflective type bottom electrode, so that light emitted from the light-emitting layer 31 toward the bottom electrode is reflected by the bottom electrode and then emitted toward the top electrode 32. The reflective bottom electrode is a conventional one, and the present invention does not limit the specific structure of the reflective bottom electrode.

In some embodiments, the bottom electrodes of the light-emitting units 3 are integrally connected such that the light-emitting units 3 share a bottom electrode on which the pixel defining structure 2 is disposed to form a plurality of light-emitting areas 20 separated from each other.

It is worth mentioning that the light emitting layers 31 of the plurality of light emitting units 3 may be adapted to emit light of at least two different colors.

At least one functional layer (not shown) may be optionally disposed between the bottom electrode of the light emitting unit 3 and the light emitting layer 31, that is, no functional layer or at least one functional layer may be disposed between the bottom electrode and the light emitting layer 31. At least one functional layer (not shown) may be optionally disposed between the top electrode 32 and the light emitting layer 31, that is, at least one functional layer may be disposed between the top electrode 32 and the light emitting layer 31. It will be understood by those skilled in the art that the functional layer may be, but is not limited to, an electron injection layer, an electron transport layer, a hole injection layer, a hole transport layer.

The light extraction unit 4 includes scattering particles 41 and a continuous phase resin 42 that confines the scattering particles 41 within the light-emitting region 20, as shown in fig. 2.

The light extraction unit 4 comprises at least one layer comprising scattering particles 41, the light extraction unit 4 optionally comprising a layer not provided with scattering particles 41. Namely:

in some embodiments, the light extraction unit 4 is a layer, and the scattering particles 41 are dispersed in the continuous phase resin 42, wherein the scattering particles 41 may be one kind or a plurality of kinds, and the scattering particles 41 may be the same size or different sizes.

In other embodiments, the light extraction unit 4 is a plurality of layers, and may each be a continuous phase resin 42 in which scattering particles 41 are dispersed,scattering particles 41 of different kinds or different sizes may be provided in each layer, for example, the light extraction unit 4 includes two layers, the first layer being a resin in which TiO with a particle size of 150nm is dispersed₂The second layer is a resin dispersed with ZrO with a particle size of 30nm₂. In the multiple layers of the light extraction unit 4, the scattering particles 41 may not be provided in several layers, for example, the light extraction unit 4 includes three layers, the first layer (the layer adjacent to the top electrode) is a resin in which TiO having a particle size of 50nm is dispersed₂The second layer is formed by dispersing ZnO with the particle size of 300nm in resin, and the third layer (the layer far away from the top electrode) is formed by resin; for another example, the light extraction unit 4 includes three layers, the first layer (the layer close to the top electrode) is a resin, the second layer is a resin in which ZnO having a particle size of 200nm is dispersed, and the third layer (the layer far from the top electrode) is a resin in which ZnO having a particle size of 20nm is dispersed. In the plurality of layers of the light extraction means 4, one layer located inside may be formed by stacking the scattering particles 41 completely.

In one embodiment of the light extraction unit 4, the scattering particles 41 are dispersed in the continuous phase resin 42, and after the resin 42 is cured or dried, the scattering particles 41 are held in a fixed position, such as the leftmost light extraction unit 4 shown in fig. 2.

In another embodiment of the light extraction unit 4, the scattering particles 41 are stacked to form a layer, and a layer formed of the resin 42 is laid over the layer of scattering particles 41 so that the scattering particles 41 are confined between the light emitting unit 3 and the resin 42, as shown in the intermediate light extraction unit 4 of fig. 2. A layer of resin may also be provided beneath the scattering particles 41.

In another embodiment of the light extraction unit 4, comprising a first layer of resin 421 and a second layer of resin 422 arranged in sequence, the first layer of resin 421 being located on the side close to the light emitting unit 3, the scattering particles 41 being dispersed in the first layer of resin 421, the second layer of resin 422 serving to ensure that the scattering particles are all "buried" in the resin, as shown in the rightmost light extraction unit 4 of fig. 2, the purpose of "burying" the scattering particles in the resin is: the upper surface of the light extraction unit 4 is ensured to have a surface with a small tension so that the material forming the auxiliary electrode 5 is not easily attached to the upper surface of the light extraction unit 4.

The resin 42 of the light extraction unit 4 may be, but is not limited to, acrylic resin, epoxy resin, urethane acrylic resin. The resin 42 may be selected from a photo-curable resin, a heat-curable resin, or a photo-thermal dual-curable resin.

In some embodiments, the scattering particles 41 have a particle size of 20nm to 400nm, and the scattering particles 41 may be, but are not limited to, one or more of inorganic particles and polymeric microspheres.

In some embodiments, the volume fraction of scattering particles 41 in light extraction unit 4 is between 5% and 90%.

In some embodiments, the light extraction unit 4 has an equivalent refractive index of 1.5 to 2.5. The equivalent refractive index in the present invention is defined as the refractive index of the scattering particles 41 x the volume fraction of the scattering particles in the light extraction unit 4 + the refractive index of the resin 42 x the volume fraction of the resin 42 in the light extraction unit 4.

The upper surface of the light extraction unit 4 is a flat surface or a slightly convex arc surface in the middle. In some embodiments, the height of the edge of the upper surface of the light extraction unit 4 does not exceed the height of the bottom surface of the auxiliary electrode 5 based on the substrate 1, and the height of the highest point of the upper surface of the light extraction unit 4 does not exceed the highest point of the auxiliary electrode 5, so that the auxiliary electrode 5 can better prevent light mixing between different light extraction units 4. It is worth mentioning that the bottom surface of the auxiliary electrode 5 is also the side of the auxiliary electrode 5 contacting the top electrode 32.

In order to avoid the influence of the fabrication of the light extraction unit 4 on the light emitting unit 3, a protective layer 6 may be further disposed between the light emitting unit 3 and the light extraction unit 4, and as shown in fig. 1, the protective layer 6 is disposed between the top electrode 32 corresponding to the light emitting unit 3 and the light extraction unit 4. The protective layer 6 may be made of organic materials by evaporation, and the organic materials may be, but are not limited to: n, N '-diphenyl-N, N' - (1-naphthyl) -1,1 '-biphenyl-4, 4' -diamine (NPB), 8-hydroxyquinoline aluminum (Alq)₃) The material is a functional material for hole transport, electron transport and the like. The protective layer 6 may be formed of a material such as a metal, a metal oxide, a metal nitride, or an oxynitride by vapor deposition or sputtering.

The material used to make the protective layer 6 may be a conductive material or a non-conductive or poorly conductive material.

In some embodiments, the material used to form the protective layer 6 is a conductive material, such as Ag or ITO, and in view of simplifying the manufacturing process, the material used to form the protective layer 6 may be integrally disposed on the top electrode 32, the conductive material inside the light-emitting region 20 forms the protective layer 6, the conductive material outside the light-emitting region 20 is not covered by the light extraction unit 4, and when the auxiliary electrode 5 is subsequently manufactured, the conductive ink is directly disposed on the portion of the conductive material, so that the portion of the conductive material and the conductive ink together form the auxiliary electrode 5.

In some embodiments, the material used for manufacturing the protection layer 6 is a non-conductive or poor-conductive material, for example, most of organic materials or inorganic materials such as silicon nitride, the top electrode 32 outside the light-emitting region 20 may be first masked by a mask, the material is only disposed on the top electrode 32 inside the light-emitting region 20 to form the protection layer 6, and after the protection layer 6 is formed, the mask is removed, so as to subsequently dispose the auxiliary electrode 5 on the top electrode 32 outside the light-emitting region 20.

In other embodiments, the material used to form the protective layer 6 is a non-conductive or poorly conductive material, and the material is soluble by the conductive ink forming the auxiliary electrode 5, such as a partially organic material, in view of simplifying the manufacturing process, the material used to form the protective layer 6 may be integrally disposed on the top electrode 32, the material within the light-emitting region 20 forms the protective layer 6, the material outside the light-emitting region 20 is not covered by the light extraction unit 4, and when the auxiliary electrode 5 is subsequently manufactured, the conductive ink dissolves the material outside the light-emitting region 20, that is, the conductive ink may diffuse to the surface of the top electrode 32, so that the auxiliary electrode 5 formed by the conductive ink is conductively connected with the top electrode 32.

The material of the protective layer 6 and the preparation process are not limited to those listed above.

In some embodiments, the total thickness of the light extraction unit 4 and the protection layer 6 is 0.65-1.85 μm, wherein the thickness of the light extraction unit 4 is not less than 300nm, and the thickness of the protection layer 6 is 40-400 nm.

In some embodiments, the pixel defining structure 2 as a whole constitutes a mesh structure. Preferably, the auxiliary electrode 5 extends as a cross-linked whole along the contour of the top surface of the pixel defining structure 2, as shown in fig. 3.

The surface tension of the upper surface of the light extraction unit 4 is 25 to 40 dyne/cm. The surface tension of the material for making the auxiliary electrode 5 is close to that of the light extraction unit 4, and the surface tension of the top electrode 32 is greater than the surface tension of the upper surface of the light extraction unit 4 and the surface tension of the material for making the auxiliary electrode 5, so that the spreadability of the material for making the auxiliary electrode 5 on the surface of the top electrode 32 is good, and the spreadability on the surface of the light extraction unit 4 is poor, which facilitates the material for making the auxiliary electrode 5 to be concentrated on the top electrode 32 without spreading on the surface of the light extraction unit 4 when making the auxiliary electrode 5. It is worth mentioning that the light extraction unit 4 is already fabricated before the fabrication of the auxiliary electrode 5.

To achieve the conductive connection of the auxiliary electrode 5 and the top electrode 32, in some embodiments, the conductive ink 50 for forming the auxiliary electrode 5 is directly disposed on the surface of the device on which the light extraction unit 4 is fabricated, as shown in fig. 10, the top electrode 32 has a high surface energy, so that the conductive ink 50 is gathered on the surface of the top electrode 32 covering the top surface of the pixel defining structure 2 without substantially spreading onto the light extraction unit 4, as shown in fig. 11, and the auxiliary electrode 5 is formed after the conductive ink 50 is cured or dried.

In other embodiments, before the auxiliary electrode 5 is disposed, the top electrode 32 is entirely covered with the conductive material 61 for forming the protective layer 6, as shown in fig. 17, at this time, the conductive ink 50 for forming the auxiliary electrode 5 is disposed directly on the surface of the device on which the light extraction unit 4 is fabricated, as shown in fig. 18, the conductive material 61 has a high surface energy, so that the conductive ink 50 is gathered on the surface of the conductive material 61 instead of being spread on the light extraction unit 4, as shown in fig. 19, and the conductive ink 50 forms the auxiliary electrode 5 together with the underlying conductive material 61 after being cured or dried.

In other embodiments, before disposing the conductive ink on the top electrode 32, the top electrode 32 is entirely covered with the organic material 60 for forming the protective layer 6, as shown in fig. 13, at which time the conductive ink 50 for forming the auxiliary electrode 5 can dissolve the organic material 60, the conductive ink 50 is disposed on the surface of the device on which the light extraction unit 4 is fabricated, as shown in fig. 14, the conductive ink 50 first dissolves the organic material 60, then the conductive component in the conductive ink 50 is deposited on the surface of the top electrode 32 covering the top surface of the pixel defining structure 2, thereby achieving conductive contact between the conductive ink 50 and the top electrode 32, as shown in fig. 15, and the exposed top electrode 32 has a high surface energy, so that the conductive ink 50 is gathered on the surface of the top electrode 32 covering the top surface of the pixel defining structure 2 without substantially spreading on the light extraction unit 4, as shown in fig. 16, the conductive ink 50 is dried or cured to form the auxiliary electrode 5.

In the production of the protective layer 6, in view of processing convenience, the conductive material 61 or the organic material 60 for protecting the top electrode 32 may be provided on the entire surface of the top electrode 32, and then the light extraction unit 4 may be provided in each light-emitting region 20 so that the surface of the device is substantially flat, and the organic material between the top electrode 32 and the light extraction unit 4 forms the protective layer 6. When the auxiliary electrode 5 is manufactured, the conductive ink 50 is disposed on the conductive material 61 or the organic material 60 that is not covered by the light extraction unit 4, the conductive ink 50 is enriched on the conductive material 61 and forms the auxiliary electrode 5 together with the conductive material 61, or the conductive ink 50 dissolves the organic material 60 and then enriches the organic material 60 on the surface of the top electrode 32 covering the top surface of the pixel defining structure 2 to form the auxiliary electrode 5.

The invention also provides a preparation method of the top-emitting light-emitting device, which sequentially comprises the following steps:

s1, providing a substrate 1 provided with a bottom electrode, the substrate 1 being provided with a pixel defining structure 2 for defining a plurality of light emitting areas 20, as shown in fig. 4;

s2, disposing the top electrode 32 in the light-emitting region 20 and on the surface of the pixel defining structure 2, as shown in fig. 6;

s3, fabricating light extraction units 4 in each light emitting region 20, the light extraction units 4 being used for collecting the light emitted from the light emitting layer 31, as shown in fig. 7, 9 or 13;

s4, an auxiliary electrode is disposed over the top surface of the pixel defining structure 2, the auxiliary electrode being conductively connected to the top electrode 32.

In step S1, the manufacturing method of the pixel defining structure 2 is the prior art, and the invention is not limited to the specific manufacturing method of the pixel defining structure 2. The bottom electrode may be formed on the substrate 1 by physical vapor deposition. The bottom electrode is provided on the substrate 1 before the pixel defining structure 2 is fabricated. The preparation method of the bottom electrode is the prior art, and the invention does not limit the preparation method of the bottom electrode.

In step S2, the top electrode 32 is formed on the entire surface, and the top electrode 32 may be formed by evaporation or sputtering. The preparation method of the top electrode 32 is the prior art, and the invention is not limited to the specific preparation method of the top electrode 32.

In some embodiments, the following steps are further included between step S1 and step S2: manufacturing a functional layer on the bottom electrode of each light-emitting region 20, wherein the functional layer includes at least one light-emitting layer 31, as shown in fig. 5; the preparation method of the light emitting layer 31 is the prior art, and the present invention does not limit the specific preparation method of the light emitting layer 31. In some embodiments, the functional layer may further include an electron injection layer, an electron transport layer, a hole injection layer, a hole transport layer, and the like. The preparation method of each functional layer is the prior art, and the invention does not limit the specific preparation method of the functional layer.

In some embodiments, step S3 includes the steps of:

s31, providing a mixed resin with scattering particles dispersed therein;

s32, filling the mixed resin into the light emitting region 20;

s33, the mixed resin is cured to form the light extraction unit 4, which is the leftmost light extraction unit 4 shown in fig. 2.

In step S32, the method of filling the mixed resin into the light-emitting region 20 may be, but is not limited to, printing, mask-in-plate ultrasonic spraying.

In other embodiments, step S3 includes the steps of:

S31A, providing scattering particles or a mixed resin in which the scattering particles are dispersed;

S32A, filling the light emitting region 20 with scattering particles or a mixed resin in which the scattering particles are dispersed;

S33A, a layer of resin is provided on the surface of the scattering particles or the mixed resin in which the scattering particles are dispersed, and the resin is cured to form the surface of the light extraction unit 4, referring to the two light extraction units 4 on the middle and the rightmost side shown in fig. 2.

In some embodiments, in step S4, the auxiliary electrode 5 is formed by drying or curing the conductive ink 50, and the conductive ink 50 may be disposed on the surface of the device on which the light extraction unit 4 has been fabricated by using a wet process such as ultrasonic spraying, slit coating, inkjet printing, or the like. After the conductive ink 50 is applied, it is preferably dried by standing and then dried or cured by heating using a hot plate, and other methods for drying or curing the ink in the prior art are also within the scope of the present application.

In some embodiments, the surface tension of the conductive ink 50 is 25 to 40dyne/cm, and the surface tension of the upper surface of the light extraction unit 4 is 25 to 40 dyne/cm. The top electrode 32 is generally made of metal or metal oxide, and the surface tension of the top electrode is much greater than that of the conductive ink 50, so that the conductive ink 50 is easier to spread on the surface of the top electrode 32; the surface tension of the upper surface of the light extraction element 4 is limited to 25 to 40dyne/cm and is close to the surface tension of the conductive ink 50, so that the spreadability of the conductive ink 50 on the upper surface of the light extraction element 4 is poor, thereby ensuring that the conductive ink 50 is self-concentrated above the top surface of the pixel defining structure 2.

In some embodiments, the conductive ink includes a conductive component, a solvent, and a modification stabilizer. Preferably, the conductive component may be, but is not limited to, one or more of the following: metal nanowires (such as nano silver wires with the cross-sectional diameter of 10-150 nm and the length of 3-100 mu m), metal nanoparticles (such as nano silver particles with the particle size of 3-10 nm), graphene and carbon nanotubes. Preferably, the mass fraction of the conductive component in the conductive ink 50 is 1-55%.

The surface of the conductive component may be modified with a ligand so that the conductive component may be better dispersed in the solvent. When the surface of the conductive component is modified with alkyl carboxylic acid ligand, the carboxyl is connected to the surface of the conductive component, the alkyl plays a role of dispersing particles, and the solvent can be selected from oily solvents such as alkane and the like. When the surface of the conductive component is modified with the alcohol amine ligand, the amine group is connected to the surface of the conductive component, the hydroxyl group plays a dispersing role, and the solvent can be selected from alcohols.

The function of the modification stabilizer is mainly to stabilize the conductive ink. In some embodiments, the modifying stabilizer may be a conductive polymer for adjusting the viscosity of the conductive ink, such as Polythiophene (PVK), poly 3, 4-ethylenedioxythiophene (PEDOT), polyaniline. In other embodiments, the modified stabilizer acts as a dispersant to aid in dispersing the conductive components in the solvent, such as a polymer-based dispersant, by means of chain entanglement or the like, to prevent aggregation and settling between the conductive components.

After the light extraction unit 4 of step S3 is manufactured, the top surface of the device is substantially flattened (the top surface of the light extraction unit 4 may be slightly convex), and only two different interfaces exist on the surface of the device, namely, the interface between the light extraction unit 4 and the environment, and the interface between the upper surface of the spacing unit between the light extraction units 4 and the environment (in some embodiments, the interface is the upper surface of the top electrode 32; in some embodiments, the interface is the organic material 60 capable of dissolving in the conductive ink 50; in other embodiments, the interface is the conductive material 61), and the conductive ink 50 is easily enriched on the upper surface of the spacing unit due to the poor affinity between the conductive ink 50 and the light extraction unit 4, so that the formed auxiliary electrode 5 is located above the top surface of the pixel defining structure 2. The spacer means a portion between the adjacent light extraction units 4.

In some embodiments, the conductive ink 50 is provided only on the top electrode 32, not on the light extraction unit 4, as shown in fig. 11, and at this time, since the surface energy of the light extraction unit 4 is small, the conductive ink 50 can be prevented from spreading onto the upper surface of the light extraction unit 4.

In other embodiments, in order to simplify the process of disposing the conductive ink 50, the conductive ink 50 is disposed on the top electrode 32 and the light extraction unit 4 on the whole surface, as shown in fig. 10, at this time, because the conductive ink 50 has poor wettability with the upper surface of the light extraction unit 4 and has good wettability with the upper surface of the spacer unit, the conductive ink 50 is automatically enriched on the upper surface of the spacer unit to form the state shown in fig. 11, and thus, after the conductive ink 50 is dried or cured, the auxiliary electrode 5 in a ring shape is formed above the top electrode 32. The annular auxiliary electrode 5 does not need to be very regular, and the auxiliary electrode 5 is ensured to form a cross-linked whole.

In some embodiments, the following steps are further included between step S2 and step S3: the protective layer 6 is provided in each light-emitting region 20, and as shown in fig. 8, the protective layer 6 covers the surface of the top electrode 32 in the light-emitting region 20. In step S3, the light extraction unit 4 is disposed on the protective layer 6, and as shown in fig. 9, since the light extraction unit 4 is disposed in the light-emitting region 20, the light extraction unit 4 does not cover the top electrode 32 on the top surface of the pixel defining structure 2. In step S4, the conductive ink 50 is disposed on the surface of the exposed top electrode 32, as shown in fig. 11, or the conductive ink 50 is disposed on the exposed top electrode 32 and the upper surface of the light extraction unit 4 integrally, as shown in fig. 10, the surface tension of the conductive ink 50 is 25 to 40dyne/cm, and the surface tension of the upper surface of the light extraction unit 4 is 25 to 40dyne/cm, because the surface tension of the top electrode 32 is greater than the surface tension of the conductive ink 50 and the upper surface of the light extraction unit 4, the conductive ink 50 will gather to the surface of the top electrode 32 corresponding to the top surface of the pixel definition structure, and form the state shown in fig. 11, so that the auxiliary electrode 5 is formed on the surface of the top electrode 32 after the conductive ink 50 is dried or cured.

In other embodiments, the following steps are further included between step S2 and step S3: an organic material 60 for protecting the top electrode 32 is integrally provided on the surface of the top electrode 32, as shown in fig. 12. In step S3, the light extraction unit 4 is disposed on the organic material 60 in the light-emitting region 20, and as shown in fig. 13, since the light extraction unit 4 is disposed in the light-emitting region 20, the light extraction unit 4 does not cover the top electrode 32 on the top surface of the pixel defining structure 2. In step S4, a conductive ink 50 is disposed on the surface of the exposed organic material 60, or the conductive ink 50 is disposed on the exposed organic material 60 and the upper surface of the light extraction unit 4 integrally, as shown in fig. 14, the conductive ink 50 is adapted to dissolve the organic material 60 located therebelow, so that the conductive component in the conductive ink 50 is electrically contacted with the top electrode 32, as shown in fig. 15, the surface tension of the conductive ink 50 is 25 to 40dyne/cm, the surface tension of the upper surface of the light extraction unit 4 is 25 to 40dyne/cm, since the surface tension of the top electrode 32 is greater than the surface tension of the conductive ink 50 and the upper surface of the light extraction unit 4, after the conductive ink 50 is disposed integrally, the conductive ink 50 dissolves the organic material 60 therebelow, and concentrates on the surface of the top electrode 32 corresponding to the top surface of the pixel defining structure, and forms the state shown in fig. 16, so that the auxiliary electrode 5 is formed on the surface of the top electrode 32 after the conductive ink is dried or cured.

In still other embodiments, the following steps are further included between step S2 and step S3: the conductive material 61 for protecting the top electrode 32 is integrally provided on the surface of the top electrode 32, and in step S3, the light extraction unit 4 is provided on the conductive material 61 in the light-emitting region 20, as shown in fig. 17, since the light extraction unit 4 is provided in the light-emitting region 20, the light extraction unit 4 does not cover the top electrode 32 on the top surface of the pixel defining structure 2. In step S4, the conductive ink 50 is disposed on the surface of the exposed conductive material 61, or the conductive ink 50 is disposed on the exposed conductive material 61 and the upper surface of the light extraction unit 4 integrally, as shown in fig. 18, the surface tension of the conductive ink 50 is 25 to 40dyne/cm, the surface tension of the top surface of the light extraction unit 4 is 25 to 40dyne/cm, since the surface tension of the top electrode 32 is greater than the surface tension of the conductive ink 50 and the upper surface of the light extraction unit 4, the conductive ink 50 is integrally disposed and then mainly gathers on the surface of the conductive material 61, and the conductive ink 50 is dried or cured to form the auxiliary electrode 5 on the surface of the top electrode 32 together with the conductive material 61 thereunder.

The advantageous effects of the present application will be further described with reference to specific examples.

[ example 1 ]

Providing a substrate with a reflecting electrode, manufacturing a pixel defining structure on the substrate, forming a plurality of light emitting areas, and then sequentially arranging PEDOT with the thickness of 40nm in each light emitting area, wherein PSS is used as a hole transport layer, TFB with the thickness of 30nm is used as a hole injection layer, a quantum dot film with the thickness of 30nm is used as a light emitting layer, ZnO nano-crystal with the thickness of 50nm is used as an electron transport layer, and ITO with the thickness of 100nm is used as a top electrode.

And manufacturing a light extraction unit on the top electrode in each light emitting area. The mixture for preparing the light extraction unit comprises solvent, polyurethane acrylic resin (UV curable resin with surface tension of about 32.6dyne/cm), and scattering particles, wherein the solvent is toluene and ethyl benzoate at a mass ratio of 1:9, and the scattering particles are TiO with particle diameter of 100nm₂The solids content of the mixture was 10% by weight. The mixture was UV cured to give a light extraction cell having a thickness of 1.25 μm and TiO in the light extraction cell₂The volume ratio of the particles to the resin is 2:8, wherein the scattering particles are TiO₂Has a refractive index of 2.5, the resin has a refractive index of 1.5, and the light extraction unit has an equivalent refractive index of 1.7.

And after the light extraction unit is manufactured, forming a basically flat surface on the upper surface of the device, printing conductive ink with the solid content of 5 wt% on the whole surface, drying, and sintering at 100 ℃ by using a hot plate to obtain the auxiliary electrode with the height of 500 nm.

The conductive component in the conductive ink is a nano silver wire, and the diameter of the nano silver wire is 20nm and the length of the nano silver wire is 2 microns. The solvent in the conductive ink comprises tripropylene glycol monomethyl ether, propylene glycol methyl ether and heptanol, and the mass ratio of the tripropylene glycol monomethyl ether to the heptanol is as follows: propylene glycol methyl ether: heptanol 5:2: 3. The stabilizer in the conductive ink is polyvinylpyrrolidone. The surface tension of the conductive ink was 29.8 dyne/cm.

[ example 2 ]

Making light extraction sheet on the top electrode in each light-emitting areaFirst layer of elements. The mixture for forming the first layer of the light extraction unit includes a solvent, urethane acrylic resin (UV curable resin, surface tension of about 32.6dyne/cm), and scattering particles, wherein the solvent is xylene and ethyl benzoate at a mass ratio of 6:4, and the scattering particles are TiO with a particle size of 400nm₂The solids content of the mixture was 5% by weight. UV curing the mixture to obtain a light extraction unit with a thickness of 800nm, wherein TiO is in the light extraction unit₂The volume ratio of the particles to the resin is 4:6, wherein the scattering particles are TiO₂Has a refractive index of 2.5, the resin has a refractive index of 1.5, and the equivalent refractive index of the first layer of the light extraction unit is 1.9.

A second layer of the light extraction unit is fabricated on the first layer of the light extraction unit. The mixture for forming the second layer of the light extraction unit included a solvent and a urethane acrylic resin (UV curable resin, surface tension of about 32.6dyne/cm), the solvent was toluene and ethyl benzoate at a mass ratio of 2:8, and the solid content of the mixture was 2 wt%. The mixture was UV cured to produce a second layer of light extraction units having a thickness of 450nm and an equivalent refractive index of 1.5.

After the light extraction unit is manufactured, a basically flat surface is formed on the upper surface of the device, conductive ink with the solid content of 20 wt% is printed on the whole surface, and the auxiliary electrode with the height of 1.5 mu m is obtained by sintering at the temperature of 100 ℃ on a hot plate after being dried.

The conductive component in the conductive ink is nano silver particles, and the particle size of the nano silver particles is 30 nm. The solvent in the conductive ink comprises cyclohexanol and heptanol, and the mass ratio of the cyclohexanol to the heptanol is as follows: heptanol 5: 5. The stabilizer in the conductive ink is polyvinyl alcohol. The surface tension of the conductive ink was 30.2 dyne/cm.

[ example 3 ]

Providing a substrate with a reflecting electrode, manufacturing a pixel defining structure on the substrate, forming a plurality of light emitting areas, and then sequentially arranging PEDOT with the thickness of 40nm in each light emitting area, wherein PSS is used as a hole transport layer, TFB with the thickness of 30nm is used as a hole injection layer, a quantum dot film with the thickness of 30nm is used as a light emitting layer, ZnO with the thickness of 50nm is used as an electron transport layer, and ITO with the thickness of 100nm is used as a top electrode.

And (3) evaporating 8-hydroxyquinoline aluminum with the thickness of 200nm on the whole surface of the top electrode to prepare a protective layer.

A first layer of light extraction units is formed on the protective layer in each light emitting region. The mixture for forming the first layer of the light extraction unit includes a solvent, urethane acrylic resin (UV curable resin having a surface tension of about 32.6dyne/cm), and scattering particles, wherein the solvent is dodecane and decane at a mass ratio of 5:5, and the scattering particles are TiO with a particle size of 50nm₂The solids content of the mixture was 2.5% by weight. UV curing the mixture to obtain a light extraction unit with a thickness of 300nm, wherein TiO is in the light extraction unit₂The volume ratio of the particles to the resin is 8:2, wherein the scattering particles are TiO₂Has a refractive index of 2.5, the resin has a refractive index of 1.5, and the equivalent refractive index of the first layer of the light extraction unit is 2.3.

A second layer of the light extraction unit is fabricated on the first layer of the light extraction unit. The mixture for forming the second layer of the light extraction unit included a solvent, urethane acrylic resin (UV curable resin, surface tension of about 32.6dyne/cm), and scattering particles, the solvent was dodecane and decane at a mass ratio of 6:4, the scattering particles were ZnO having a particle size of 300nm, and the solid content of the mixture was 3 wt%. After the mixture was UV cured, a light extraction unit having a thickness of 400nm was prepared, the volume ratio of ZnO to resin in the light extraction unit was 6:4, wherein the refractive index of the scattering particles ZnO was 2, the refractive index of the resin was 1.5, and the equivalent refractive index of the second layer of the light extraction unit was 1.8.

A third layer of the light extraction unit is fabricated on the second layer of the light extraction unit. The mixture for making the third layer of the light extraction unit comprised solvent and urethane acrylic resin (UV curable resin, surface tension about 32.6dyne/cm), the solvent being dodecane and decanol in a 6:4 mass ratio, the mixture having a solids content of 1.5 wt%. The mixture was UV cured to produce a light extraction unit third layer having a thickness of 350nm and an equivalent refractive index of 1.5.

After the light extraction unit is manufactured, a substantially flat surface is formed on the upper surface of the device, conductive ink with the solid content of 55 wt% is printed on the whole surface, and the auxiliary electrode with the height of 1.2 microns is obtained by sintering at the temperature of 100 ℃ on a hot plate after being dried.

The conductive component in the conductive ink is nano silver particles, and the particle size of the nano silver particles is 12 nm. The solvent in the conductive ink comprises chlorobenzene and 1, 3-dimethoxybenzene, and the mass ratio of the chlorobenzene to the 1, 3-dimethoxybenzene is as follows: 1, 3-dimethoxybenzene ═ 2: 8. The stabilizer in the conductive ink is poly 9-vinylcarbazole (PVK). The surface tension of the conductive ink was 34 dyne/cm.

[ example 4 ]

ITO with a thickness of 40nm is subjected to Radio Frequency (RF) sputtering on the whole surface of the top electrode to obtain a protective layer.

A first layer of light extraction units is formed on the protective layer in each light emitting region. The mixture for making the first layer of the light extraction unit included solvent and urethane acrylic resin (UV curable resin, surface tension about 32.6dyne/cm), the solvent was dodecane and decanol in a 6:4 mass ratio, and the mixture had a solid content of 1.8 wt%. After UV curing of the mixture, a first layer of light extraction units having a thickness of 50nm and an equivalent refractive index of 1.5 was obtained.

A second layer of the light extraction unit is fabricated on the first layer of the light extraction unit. The mixture for forming the second layer of the light extraction unit included a solvent, urethane acrylic resin (UV curable resin, surface tension of about 32.6dyne/cm), and scattering particles, the solvent was dodecane and decane in a mass ratio of 6:4, the scattering particles were ZnO having a particle size of 200nm, and the solid content of the mixture was 2.5 wt%. After the mixture was UV cured, a light extraction unit having a thickness of 400nm was prepared, the volume ratio of ZnO to resin in the light extraction unit was 5:5, wherein the refractive index of the scattering particles ZnO was 2, the refractive index of the resin was 1.5, and the equivalent refractive index of the second layer of the light extraction unit was 1.75.

A third layer of the light extraction unit is fabricated on the second layer of the light extraction unit. The mixture for making the third layer of the light extraction unit included solvent, urethane acrylic resin (UV curable resin, surface tension about 32.6dyne/cm), and scattering particles, the solvent was dodecane and decane at a mass ratio of 8:2, the scattering particles were ZnO with a particle size of 20nm, and the solid content of the mixture was 4 wt%. After the mixture was UV cured, a light extraction unit having a thickness of 760nm was prepared, the volume ratio of ZnO to resin in the light extraction unit was 1:9, wherein the refractive index of the scattering particles ZnO was 2, the refractive index of the resin was 1.5, and the equivalent refractive index of the third layer of the light extraction unit was 1.55.

After the light extraction unit is manufactured, a substantially flat surface is formed on the upper surface of the device, conductive ink with the solid content of 55 wt% is printed on the whole surface, and the auxiliary electrode with the height of 1.2 microns is obtained by drying in the air and sintering at the temperature of 80 ℃ on a hot plate.

The conductive component in the conductive ink is a nano silver wire, and the diameter of the nano silver wire is 10nm and the length of the nano silver wire is 3 microns. The solvent in the conductive ink comprises isopropanol and butanol, wherein the mass ratio of the isopropanol to the butanol is as follows: butanol 5: 5. The stabilizer in the conductive ink is polyvinyl alcohol. The surface tension of the conductive ink was 29 dyne/cm.

[ example 5 ]

A mask plate is arranged on the top electrode, the mask plate covers the top electrode between the light emitting regions, and Si with the thickness of 100nm is subjected to Radio Frequency (RF) sputtering on the top electrode in the light emitting region₃N₄And obtaining the protective layer.

A first layer of light extraction units is formed on the protective layer in each light emitting region. The mixture for forming the first layer of the light extraction unit includes a solvent, a urethane acrylic resin (UV curable resin, surface tension resin)About 32.6dyne/cm) and scattering particles of TiO 150nm in a solvent of ethyl benzoate in xylene at a mass ratio of 2:8₂The solids content of the mixture was 3% by weight. UV curing the mixture to obtain a light extraction unit with a thickness of 400nm, wherein TiO is in the light extraction unit₂The volume ratio of the particles to the resin is 9:1, wherein the scattering particles are TiO₂Has a refractive index of 2.5, the resin has a refractive index of 1.5, and the equivalent refractive index of the first layer of the light extraction unit is 2.4.

A second layer of the light extraction unit is fabricated on the first layer of the light extraction unit. The mixture for forming the second layer of the light extraction unit comprises solvent, urethane acrylic resin (UV curable resin with surface tension of about 32.6dyne/cm) and scattering particles, wherein the solvent is toluene and ethyl benzoate at a mass ratio of 2:8, and the scattering particles are ZrO with particle size of 30nm₂The solids content of the mixture was 2.5% by weight. The mixture was UV-cured to give a light extraction cell having a thickness of 750nm, in which ZrO was present₂The volume ratio of the particles to the resin is 0.5:9.5, wherein the scattering particles are ZrO₂Has a refractive index of 2.16, the resin has a refractive index of 1.5, and the equivalent refractive index of the first layer of the light extraction unit is 1.53.

After the light extraction unit is manufactured, a basically flat surface is formed on the upper surface of the device, conductive ink with the solid content of 35 wt% is printed on the whole surface, and the auxiliary electrode with the height of 800nm is obtained by drying in the air and sintering at the temperature of 80 ℃ on a hot plate.

The conductive component in the conductive ink is a nano silver wire, the diameter of which is 10nm and the length of which is 3 μm. The solvent in the conductive ink comprises isopropanol and butanol, wherein the mass ratio of the isopropanol to the butanol is as follows: butanol 4: 6. The stabilizer in the conductive ink is polyvinylpyrrolidone. The surface tension of the conductive ink was 29 dyne/cm.

Comparative example 1

Comparative example 2

It is worth mentioning that, in the above embodiments, the solid content of the conductive ink refers to the mass ratio of the conductive component in the conductive ink.

The luminance of 100ppi pixel substrates (1.2 inch) at different positions (divided into 6 regions, numbered 1-6 from near to far from the electrode, respectively) was measured using PR670(Photo Research Inc)4v at a constant voltage, and the results are shown in table 1.

TABLE 1

Numbering

1

2

3

4

5

6

Example 1

7124cd/m²

7215cd/m²

7094cd/m²

7195cd/m²

7205cd/m²

7167cd/m²

Comparative example 1

2902cd/m²

2879cd/m²

2765cd/m²

2801cd/m²

2594cd/m²

2603cd/m²

Comparative example 2

6120cd/m²

6209cd/m²

6106cd/m²

6053cd/m²

5867cd/m²

5901cd/m²

As can be seen from the above test data, the display panel of example 1 has higher luminance at the same voltage, and the luminance decreases less significantly as the distance from the electrode increases; in contrast, in comparative example 2, although relatively good brightness is obtained depending on the light extraction structure, the brightness reduction trend is obvious, and it can be seen that the 100nm ITO top electrode has insufficient conductive capability and obvious voltage drop; in contrast, comparative example 1 has the lowest brightness and the falling tendency is very remarkable because it has no light extraction structure.

The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are within the protection scope of the present invention.

Claims

1. A top-emitting light emitting device comprising: a substrate; a pixel defining structure disposed over the substrate for defining a plurality of light emitting areas; the top electrode extends outwards from the inside of each light-emitting area and covers the top surface of the pixel defining structure; characterized in that the top-emitting light-emitting device further comprises:

the light extraction units are arranged in the light emitting areas and are arranged on the light emitting sides of the light emitting units; the surface tension of the top electrode is greater than the surface tension of the upper surface of the light extraction unit; and

an auxiliary electrode disposed over a top surface of the pixel defining structure, the auxiliary electrode being conductively connected with the top electrode; the auxiliary electrodes are in a plurality of ring shapes, and the auxiliary electrodes form a cross-linked whole body.

2. The top-emitting light-emitting device according to claim 1, wherein the pixel defining structure is a mesh structure.

3. The top-emission light-emitting device according to claim 1, wherein a surface tension of an upper surface of the light extraction unit is 25 to 40 dyne/cm.

4. The top-emission light-emitting device according to claim 1, wherein the light extraction unit includes scattering particles and a continuous-phase resin that confines the scattering particles in the light-emitting region.

5. The top-emitting light-emitting device according to claim 4, wherein the light extraction unit comprises at least one layer containing the scattering particles, and the light extraction unit optionally comprises a layer in which no scattering particles are provided.

6. The top-emission light-emitting device according to claim 4, wherein the light extraction unit has an equivalent refractive index of 1.5 to 2.5.

7. The top-emission light-emitting device according to claim 4, wherein the upper surface of the light extraction unit is a flat surface or a curved surface with a convex middle portion, the height of the edge of the upper surface of the light extraction unit does not exceed the height of the bottom surface of the auxiliary electrode, and the height of the highest point of the upper surface of the light extraction unit does not exceed the highest point of the auxiliary electrode.

8. The top-emission light-emitting device according to any one of claims 1 to 7, wherein a protective layer is provided between the top electrode corresponding to the light-emitting unit and the light extraction unit, and the thickness of the protective layer is 40 to 400 nm.

9. A method for preparing a top-emitting light-emitting device is characterized by comprising the following steps:

s3, forming light extraction units in each of the light emitting regions;

s4, providing an auxiliary electrode above the top surface of the pixel defining structure, the auxiliary electrode being conductively connected to the top electrode; in step S4, the auxiliary electrode is formed by drying or curing the conductive ink; and a spacing unit is arranged between the light extraction units, the surface energy of the upper surface of the spacing unit is greater than that of the upper surface of the adjacent light extraction unit, conductive ink is arranged on the upper surface of the spacing unit and/or the light extraction unit, the conductive ink is enriched to the upper surface corresponding to the top surface of the pixel definition structure, and the auxiliary electrode is formed after the conductive ink is dried or cured.

10. The method of manufacturing a top-emission light emitting device according to claim 9, wherein the surface tension of the conductive ink is 25 to 40dyne/cm, and the surface tension of the upper surface of the light extraction unit is 25 to 40 dyne/cm.

11. The method of claim 9, wherein the conductive ink comprises a conductive component selected from one or more of the following: the conductive ink comprises metal nanowires, metal nanoparticles, graphene and carbon nanotubes, wherein the mass fraction of the conductive component in the conductive ink is 1-55%.

12. The method for manufacturing a top-emission light-emitting device according to claim 9, further comprising a step between the step S2 and the step S3 of: arranging a protective layer in each light-emitting area, wherein the protective layer covers the surface of the top electrode in the light-emitting area; in step S3, disposing the light extraction unit on the protective layer in the light emitting region; in step S4, the conductive ink is disposed on the exposed surface of the top electrode, and the conductive ink is dried or cured to form the auxiliary electrode.

13. The method for manufacturing a top-emission light-emitting device according to claim 9, further comprising a step between the step S2 and the step S3 of: arranging a protective layer on the surface of the top electrode, wherein the material of the protective layer comprises an organic material, and the organic material is soluble in the conductive ink; in step S3, providing a light extraction unit on the protective layer in the light emitting region; in the step S4, the conductive ink is disposed on the surface of the exposed protective layer, the conductive ink dissolves the organic material of the protective layer, and the conductive ink is dried or cured to form the auxiliary electrode.

14. The method for manufacturing a top-emission light-emitting device according to claim 9, further comprising a step between the step S2 and the step S3 of: arranging a protective layer on the surface of the top electrode, wherein the material of the protective layer comprises a conductive material; in step S3, providing a light extraction unit on the protective layer in the light emitting region; in the step S4, the conductive ink is disposed on the surface of the exposed protective layer, and the conductive ink and the protective layer form the auxiliary electrode together after being dried or cured.

15. The method of claim 14, wherein the conductive material is selected from one or more of a metal, a metal oxide, or a metal nitride.