CN111463353B

CN111463353B - Display substrate, preparation method thereof and display device

Info

Publication number: CN111463353B
Application number: CN202010202661.8A
Authority: CN
Inventors: 崔颖; 侯文军
Original assignee: BOE Technology Group Co Ltd
Current assignee: BOE Technology Group Co Ltd
Priority date: 2020-03-20
Filing date: 2020-03-20
Publication date: 2023-06-30
Anticipated expiration: 2040-03-20
Also published as: CN111463353A

Abstract

The invention discloses a display substrate, a preparation method thereof and a display device. A display substrate, comprising: a substrate base; the pixel defining layer is arranged on one side of the substrate base plate and defines a plurality of sub-pixel areas; and the light-emitting structure layer is arranged on one side of the pixel defining layer, which is away from the substrate base plate, and is positioned in the sub-pixel region, the light-emitting structure layer comprises a hole injection layer, and when the hole injection ink is formed in the sub-pixel region by adopting an ink-jet printing method, the hole injection ink of at least two adjacent sub-pixel regions is communicated. The display substrate can ensure that the film thickness of the hole injection layer of at least two adjacent sub-pixel areas is uniform, reduce the film thickness difference between the sub-pixels and improve the brightness uniformity between the pixels.

Description

Display substrate, preparation method thereof and display device

Technical Field

The invention relates to the technical field of display, in particular to a display substrate, a preparation method thereof and a display device.

Background

The Organic Light Emitting Diode (OLED) display substrate has the advantages of low energy consumption, low production cost, self-luminescence, wide visual angle, high response speed and the like, and is widely applied to the display fields of mobile phones, tablet computers, digital cameras and the like.

Currently, OLED devices can be formed by inkjet printing methods. However, an error in the amount of ink ejected between the plurality of nozzles may cause uneven film thickness between the sub-pixels, resulting in a difference in luminance uniformity between the pixels.

Disclosure of Invention

The embodiment of the invention aims to provide a display substrate for improving the uniformity of the film forming thickness of sub-pixels.

In order to solve the above technical problems, an embodiment of the present invention provides a display substrate, including:

a substrate base;

the pixel defining layer is arranged on one side of the substrate base plate and defines a plurality of sub-pixel areas; the method comprises the steps of,

the light-emitting structure layer is arranged on one side, away from the substrate base plate, of the pixel defining layer and is located in the sub-pixel area, the light-emitting structure layer comprises a hole injection layer, and when hole injection ink is formed in the sub-pixel area by adopting an ink-jet printing method, the hole injection ink of at least two adjacent sub-pixel areas is communicated.

In some of the possible implementations of the present invention,

the pixel defining layer includes a first pixel partition wall extending along a first direction and a second pixel partition wall extending along a second direction, the first pixel partition wall and the second pixel partition wall intersecting to define the sub-pixel region, the first pixel partition wall having a height smaller than a height of the second pixel partition wall, the first direction and the second direction being perpendicular to each other, a dimension of the sub-pixel region in the first direction being smaller than a dimension in the second direction,

When the hole injection ink is formed in the sub-pixel areas by adopting an ink jet printing method, the hole injection ink in the sub-pixel areas between two adjacent second pixel partition walls is communicated.

In some possible implementations, the first pixel partition wall has a height of 0.1 μm to 0.8 μm and the second pixel partition wall has a height of 0.9 μm to 1.5 μm.

In some possible implementations, the first pixel partition includes a partition layer and a modification layer disposed on a side surface of the partition layer facing away from the substrate, the modification layer changing from a lyophobic property to a lyophobic property when a temperature is greater than or equal to a critical temperature.

In some possible implementations, the modified layer is also located on both side wall surfaces of the partition wall layer.

In some possible implementations, the material of the modified layer includes poly (N-isopropylacrylamide), and the critical temperature is 30 ℃ to 34 ℃.

In some possible implementations, the pixel defining layer includes a first retaining wall defining a pixel region and a second retaining wall located within the first retaining wall and defining a sub-pixel region, a channel is disposed between at least one of the second retaining walls and the substrate in the pixel region, the sub-pixel regions located on both sides of the channel are communicated through the channel,

When hole injection ink is formed in the sub-pixel area at one side of the channel by adopting an ink jet printing method, the hole injection ink in the sub-pixel areas at two sides of the channel are communicated.

In some possible implementations, the height of the channel is less than or equal to the film thickness of the hole injection layer, and the hole injection layers of the sub-pixel regions located at two sides of the channel are communicated through the channel.

In some possible implementations, the light emitting structure layer further includes a hole transport layer disposed on a side of the hole injection layer facing away from the substrate, the height of the channel is greater than or equal to a film thickness of the hole injection layer, the height of the channel is less than or equal to a sum of the film thicknesses of the hole transport layer and the hole injection layer, and the hole injection layer and the hole transport layer of the sub-pixel regions disposed on both sides of the channel are all communicated through the channel.

In some possible implementations, the pixel region includes a red sub-pixel region and a green sub-pixel region, and the channel is located between the red sub-pixel region and the green sub-pixel region.

In order to solve the above technical problems, an embodiment of the present invention further provides a method for manufacturing a display substrate, including:

Forming a pixel defining layer on one side of a substrate base plate, wherein the pixel defining layer defines a plurality of sub-pixel areas;

and printing hole injection ink in an inkjet mode on one side, away from the substrate, of the pixel defining layer, wherein the hole injection ink in at least two adjacent sub-pixel areas is communicated.

In some of the possible implementations of the present invention,

the pixel defining layer is formed on one side of the substrate, and defines a plurality of sub-pixel regions, including:

forming a partition wall layer extending along a first direction and a second pixel partition wall extending along a second direction on one side of the substrate, wherein the partition wall layer and the second pixel partition wall are intersected to define the sub-pixel region, the height of the partition wall layer is smaller than that of the second pixel partition wall, the first direction and the second direction are mutually perpendicular, and the dimension of the sub-pixel region in the first direction is smaller than that in the second direction;

forming a modified layer on one side of the partition wall layer away from the substrate, wherein when the temperature is greater than or equal to the critical temperature, the modified layer is changed from the lyophile property to the lyophobic property, the first pixel partition wall comprises a partition wall layer and a line-changing layer which are overlapped, the height of the first pixel partition wall is smaller than that of the second pixel partition wall,

The inkjet printing of hole injection ink on a side of the pixel defining layer facing away from the substrate base plate comprises:

ink-jet printing hole injection ink on one side of the pixel defining layer, which is away from the substrate, wherein the hole injection ink in a plurality of sub-pixel areas between two adjacent second pixel partition walls is communicated;

and curing the hole injection ink, wherein the modification layer is changed from lyophile property to lyophobic property, and the hole injection ink positioned at two sides of the first pixel partition wall is limited in a corresponding sub-pixel area to form a film.

In some of the possible implementations of the present invention,

the substrate comprises a pixel region, wherein the pixel region comprises a plurality of sub-pixel regions, and a sacrificial layer is formed between at least two adjacent sub-pixel regions in one pixel region; forming a first retaining wall and a second retaining wall on one side of the sacrificial layer, which is away from the substrate, wherein the first retaining wall is positioned between adjacent pixel areas, and the second retaining wall is positioned between adjacent sub-pixel areas in the first retaining wall;

Removing the sacrificial layer to form a channel, communicating the sub-pixel areas at two sides of the channel through the channel,

and (3) carrying out ink jet printing on the sub-pixel areas at one side of the channel to form hole injection ink, wherein the hole transport ink flows between the sub-pixel areas at two sides of the channel to fill the sub-pixel areas at two sides of the channel.

In order to solve the technical problems, the embodiment of the invention also provides a display device, which comprises the display panel.

When the hole injection ink is formed in the sub-pixel areas by adopting an ink jet printing method, the hole injection ink of at least two adjacent sub-pixel areas is communicated. In this way, the at least two adjacent sub-pixel areas which are communicated can form uniform hole injection ink, so that the film thickness of the hole injection layer of the at least two adjacent sub-pixel areas is uniform, the film thickness difference between the sub-pixels is reduced, and the brightness uniformity between the pixels is improved. On the other hand, the hole injection ink of at least two adjacent sub-pixel areas is communicated, when the spray head sprays ink to one of the sub-pixel areas, the ink flows to the other sub-pixel area, the ink output requirement of the spray head is increased, the spray head with small ink output is not needed to be replaced, the time consumption of replacing the spray head is avoided, and a hole injection layer can be formed in the at least two adjacent sub-pixel areas at the same time, so that the process is simplified, and the mass production is facilitated.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate and do not limit the invention.

FIG. 1a is a schematic diagram showing the film thickness in the long axis direction of a sub-pixel;

FIG. 1b is a schematic view showing the thickness of the film layer in the short axis direction of the sub-pixel;

FIG. 2 is a schematic top view of a display substrate according to an exemplary embodiment of the invention;

FIG. 3 is a schematic view of the cross-sectional structure A-A of FIG. 2;

FIG. 4 is a schematic view of the cross-sectional structure B-B in FIG. 2;

FIG. 5 is a schematic cross-sectional structure of a display substrate in an exemplary embodiment;

FIG. 6a is a schematic view showing a cross-sectional C-C structure of the substrate of FIG. 2 after forming a partition layer;

FIG. 6b is a schematic view of the cross-sectional C-C structure of the substrate of FIG. 2 after formation of a modified layer;

FIG. 7a is a schematic diagram showing a top view of a substrate after hole injection ink is inkjet printed;

FIG. 7b is a schematic view of the cross-sectional D-D structure of FIG. 7 a;

FIG. 8 is a schematic top view of a display substrate according to an exemplary embodiment of the invention;

FIG. 9 is a schematic view of the cross-sectional E-E structure of FIG. 8;

FIG. 10 is a schematic view of the cross-sectional structure of F-F in FIG. 8;

FIG. 11 is a schematic view showing the E-E cross-sectional structure of the display substrate shown in FIG. 8 in an exemplary embodiment;

FIG. 12 is a schematic view showing a cross-sectional F-F structure of the display substrate shown in FIG. 8 in an exemplary embodiment;

FIG. 13 is a schematic view showing the F-F cross-sectional structure after forming a sacrificial layer in a substrate;

FIG. 14 is a schematic view showing the cross-sectional F-F structure of the substrate after forming a second retaining wall;

FIG. 15 is a schematic view showing a cross-sectional F-F structure of a substrate after hole injection ink is inkjet printed in a red sub-pixel region or a green sub-pixel region;

FIG. 16 is a schematic view showing a cross-sectional F-F structure of a substrate after a hole injection layer is formed in a red sub-pixel region and a green sub-pixel region;

FIG. 17 is a schematic view showing the cross-sectional F-F structure of the substrate after the hole transporting ink is ink-jet printed in the red sub-pixel region or the green sub-pixel region.

Reference numerals illustrate:

10-a substrate base plate; 20, 50-pixel definition layer; 21-first pixel partition walls;

211-partition layers; 212-a modified layer; 22-second pixel partition walls;

30-a sub-pixel region; 31-a first electrode; 321-a hole injection layer;

33-a second electrode; 51—a first retaining wall; 52-a second retaining wall;

521-a sacrificial layer; 60-sacrificial layer.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail hereinafter with reference to the accompanying drawings. It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be arbitrarily combined with each other.

The "height" described hereinafter is the dimension in the direction perpendicular to the substrate base plate.

When the OLED device is prepared by adopting an ink-jet printing method, uneven thickness of a display film layer among sub-pixels is easily caused due to errors of ink-jet amounts among a plurality of nozzles, and brightness uniformity difference among pixels is caused.

The inventors have employed various schemes to improve the uniformity of the display film thickness within a subpixel. The sub-pixel is generally in a long strip shape, fig. 1a is a schematic diagram showing the film thickness in the long axis direction of the sub-pixel, and fig. 1b is a schematic diagram showing the film thickness in the short axis direction of the sub-pixel, as can be seen from fig. 1a and 1b, the film thickness uniformity in the long axis direction of the sub-pixel can reach more than 80%, the film thickness uniformity in the short axis direction is only about 50%, the film thickness uniformity in the long axis direction in the sub-pixel is improved, but the film thickness uniformity in the short axis direction is worse than the film thickness uniformity in the long axis direction, the film formation uniformity in the sub-pixel is severely limited in the short axis direction, and further improvement of the film formation uniformity in the short axis direction of the sub-pixel is required.

On the other hand, the ink-jet printing polymer electroluminescent display (PLED) technology has the advantages of simple operation, low cost, simple process, easy realization of large size and the like, and is expected to realize industrialization rapidly along with the continuous development of high-performance polymer materials and the further improvement of film preparation technology.

For a full print top emission display product, its resolution is 160ppi, the subpixel size can be 31.9 μm 107.8 μm, and the aperture ratio 38.3%. Through simulation calculation, in the top emission display product, the thickness of the Hole Injection Layer (HIL) required in the red sub-pixel and the green sub-pixel is 10nm, the volume of the required ink is 2.7pl, and the ink quantity is less than 1 drop for a 10pl nozzle of G2.5, so that the light emitting devices of the red sub-pixel and the green sub-pixel are difficult to prepare by adopting the 10pl nozzle of G2.5. To form the hole injection layer in the red and green sub-pixels, the ink or the head needs to be replaced constantly.

In order to solve the technical problems, an embodiment of the invention provides a display substrate. The display substrate includes: a substrate base; the pixel defining layer is arranged on one side of the substrate base plate and defines a plurality of sub-pixel areas; and the light-emitting structure layer is arranged on one side of the pixel defining layer, which is away from the substrate base plate, and is positioned in the sub-pixel region, the light-emitting structure layer comprises a hole injection layer, and when the hole injection ink is formed in the sub-pixel region by adopting an ink-jet printing method, the hole injection ink of at least two adjacent sub-pixel regions is communicated.

The technical contents of the present invention will be described in detail by means of specific examples.

Fig. 2 is a schematic top view of a display substrate according to an exemplary embodiment of the present invention, fig. 3 is a schematic cross-sectional view of A-A in fig. 2, and fig. 4 is a schematic cross-sectional view of B-B in fig. 2. In one exemplary embodiment, as shown in fig. 2, 3 and 4, the display substrate includes a substrate base 10 and a pixel defining layer 20 disposed at one side of the substrate base 10. The pixel defining layer 20 includes a first pixel partition wall 21 and a second pixel partition wall 22. The first pixel partition walls 21 extend in a first direction X (row direction in fig. 2), and the second pixel partition walls 22 extend in a second direction Y (column direction in fig. 2). The first pixel partition wall 21 and the second pixel partition wall 22 cross to define a sub-pixel region 30. The height of the first pixel partition wall 21 is smaller than the height of the second pixel partition wall 22. The second direction is perpendicular to the first direction, and the size of the sub-pixel region 30 in the second direction X is smaller than that in the second direction Y. "height" is the dimension in a direction perpendicular to the substrate base. The display substrate further comprises a light emitting structure layer disposed on a side of the pixel defining layer 20 facing away from the substrate and located in the sub-pixel region. The light emitting structure layer includes a hole injection layer 321, and when hole injection ink is formed in the sub-pixel region by using an inkjet printing method, the hole injection ink in the sub-pixel regions located between two adjacent second pixel partition walls 22 is communicated.

When the hole injection ink is formed by the inkjet printing method, the height of the liquid ink is greater than the height of the first pixel partition wall 21 and less than the height of the second pixel partition wall 22 before curing. Thus, the liquid ink may communicate between the plurality of sub-pixel regions located between the adjacent two second pixel partition walls 22, that is, the inks of the plurality of sub-pixel regions located in the same column communicate with each other. Therefore, uneven film formation caused by inconsistent ejection volumes of the nozzles can be avoided, so that the film formation of the sub-pixels on the same row is uniform, and the luminous quality of the display device is improved.

In one exemplary embodiment, as shown in fig. 3 and 4, the height d1 of the first pixel partition wall 21 is 0.1 μm to 0.8 μm and the height d2 of the second pixel partition wall 22 is 0.9 μm to 1.5 μm.

In one exemplary embodiment, as shown in fig. 3, the first pixel partition wall 21 includes a partition wall layer 211 and a modification layer 212 disposed at a side of the partition wall layer 211 facing away from the substrate base plate 10, and when the temperature is greater than or equal to a critical temperature, the modification layer 212 changes from a lyophobic property to a lyophobic property. In one exemplary embodiment, the modification layer 212 is located on a surface of the partition wall layer 211 on a side remote from the base substrate, that is, the modification layer 212 is located on a top surface of the partition wall layer 211. The lyophilic properties of the modification layer 212 facilitate communication between subpixel areas of the same column when printing ink. In the ink curing process, the temperature of the display substrate is raised to reach the critical temperature, so that the modification layer 212 is changed from the lyophile property to the lyophobic property, and thus the top surface of the first pixel partition wall 21 becomes lyophobic, and the inks on both sides of the first pixel partition wall 21 in the same column are gradually limited in the corresponding sub-pixel regions, so that crosstalk between sub-pixels is prevented.

In one exemplary embodiment, the modification layer 212 covers an exposed surface of the partition wall layer 211, that is, the modification layer 212 is located on a surface of a side of the partition wall layer 211 remote from the substrate base plate 10 and on both side wall surfaces of the partition wall layer 211, as shown in fig. 3. In the ink curing process, the modification layer 212 is changed from the lyophile characteristic to the lyophobic characteristic, so that the modification layer 212 covers the side surface of the partition wall layer 211, the ink can be prevented from climbing to the side wall of the first pixel partition wall 21 in the curing process, the film thickness of the position close to the first pixel partition wall 21 after film formation is prevented from being overlarge, and the film thickness uniformity of the sub-pixel area is further improved.

In one exemplary embodiment, the material of the modification layer 212 may include poly (N-isopropyl acrylamide) (PNIPAM). Those skilled in the art will appreciate that the material of the modifying layer 212 is not limited to poly (N-isopropylacrylamide), and that the lyophobic nature of the material may be selected to produce a modifying layer as long as the lyophobic nature of the material varies with temperature.

In one exemplary embodiment, the critical temperature is 30 ℃ to 34 ℃. In one exemplary embodiment, the critical temperature is 32 ℃.

In one exemplary embodiment, as shown in fig. 3 and 4, the display substrate may further include a first electrode 31, the first electrode 31 being located between the substrate 10 and the pixel defining layer 20, the first electrode 31 being located in the sub-pixel region 30. The first electrode 31 may be an anode. In the top-emitting OLED display substrate, the material of the first electrode 31 may be a conductive material having a light reflecting effect, such as magnesium aluminum alloy, magnesium silver alloy, calcium silver alloy, or the like. In the bottom-emission or double-emission OLED display substrate, the material of the first electrode 31 may be a conductive material having a light-transmitting effect, such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO), or the like.

Fig. 5 is a schematic cross-sectional structure of a display substrate in an exemplary embodiment. In an exemplary embodiment, as shown in fig. 5, the light emitting structure layer may further include a hole transport layer, an organic light emitting layer, an electron injection layer, and other film layers sequentially stacked on a side of the hole injection layer facing away from the substrate. In an exemplary embodiment, the display substrate may further include a second electrode 33, which may be a cathode electrode, disposed at a side of the light emitting structure layer remote from the substrate 10. In an exemplary embodiment, the display substrate may further include a package structure layer disposed at a side of the second electrode 33 facing away from the substrate 10.

Each of the film layers of the light emitting structure layer may be formed by inkjet printing. When each film layer of the luminous structure layer is formed in the sub-pixel area by adopting an ink-jet printing method, before the film layers are solidified, the inks in the sub-pixel areas in the same row are mutually communicated, and the second pixel partition walls block the inks from flowing to other rows. Therefore, uneven film formation caused by inconsistent ejection volumes of all the nozzles is avoided, the film thickness of the light-emitting structure layer on the same column is uniform, and the light-emitting quality of the display device is improved.

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

S1: forming a pixel defining layer on one side of a substrate base plate, wherein the pixel defining layer defines a plurality of sub-pixel areas;

s2: and printing hole injection ink in an inkjet mode on one side, away from the substrate, of the pixel defining layer, wherein the hole injection ink in at least two adjacent sub-pixel areas is communicated.

In one exemplary embodiment, S1 may include:

and a modified layer is formed on one side of the partition wall layer, which is away from the substrate, and when the temperature is greater than or equal to the critical temperature, the modified layer is changed from the lyophile characteristic to the lyophobic characteristic, the first pixel partition wall comprises a partition wall layer and a line-changing layer which are overlapped, and the height of the first pixel partition wall is smaller than that of the second pixel partition wall.

In one exemplary embodiment, S2 may include:

The technical scheme of the display substrate shown in fig. 2 according to the embodiment of the invention is described in detail below through the preparation process of the display substrate. It is to be understood that, in the present embodiment, the "patterning" includes processes of coating photoresist, mask exposure, developing, etching, stripping photoresist, etc. when the patterned material is inorganic material or metal, and processes of mask exposure, developing, etc. when the patterned material is organic material, the "patterning" includes processes of evaporation, deposition, coating, etc. in the present embodiment, all processes are mature preparation processes in the related art.

S11: a substrate base 10 is provided. As will be appreciated by those skilled in the art, the substrate base 10 may include a substrate and a thin film transistor array layer disposed on one side of the substrate.

S12: a plurality of first electrodes 31 are formed on one side of the substrate 10, and the plurality of first electrodes 31 are arranged in an array. The first electrode 31 may be formed using a conventional technique in the art, and will not be described herein.

S13: a pixel defining layer 20 is formed on a side of the first electrode 31 facing away from the substrate 10. The pixel defining layer 20 includes a first pixel partition wall 21 and a second pixel partition wall 22. The first pixel partition walls 21 extend in the first direction X, and the second pixel partition walls 22 extend in the second direction Y. The first pixel partition wall 21 and the second pixel partition wall 22 define a sub-pixel region 30. The height of the first pixel partition wall 21 is smaller than the height of the second pixel partition wall 22. In one exemplary embodiment, this step may include:

s1311: the partition wall layer 211 and the second pixel partition wall 22 are formed through a one-time patterning process, the partition wall layer 211 is positioned between two adjacent first electrodes 31 and extends along a first direction, the second pixel partition wall 22 is positioned between two adjacent first electrodes 31 and extends along a second direction, the height of the partition wall layer 211 is smaller than that of the second pixel partition wall 22, the partition wall layer 211 and the second pixel partition wall 22 define a sub-pixel region 30, the size of the sub-pixel region 30 in the second direction is larger than that of the sub-pixel region 30 in the first direction, and the first electrodes 31 correspond to the sub-pixel region 30. This step may include: forming a partition film on a side of the first electrode 31 facing away from the substrate 10; the partition film is patterned by using a gray mask, the partition film 211 is formed by reserving a part of the thickness of the partition film at the position of the partition layer 211, the partition film with the whole thickness is reserved at the position of the second pixel partition 22 to form the second pixel partition 22, and the other partition films are removed, as shown in fig. 6a, fig. 6a is a schematic view showing the C-C section structure of the substrate after the partition layer is formed in fig. 2. The height of the partition wall layer 211 is smaller than that of the second pixel partition wall 22, the first direction and the second direction are perpendicular to each other, and the size of the sub-pixel region 30 in the second direction is larger than that in the first direction. Wherein, the material of the partition wall film can be resin, organic silicon or silicon dioxide, etc.

S1312: a modification layer 212 is formed on a side of the partition wall layer 211 facing away from the base substrate 10, and when the temperature is greater than or equal to the critical temperature, the modification layer 212 changes from a lyophile property to a lyophobic property. This step may include: forming a modified thin film on a side of the partition wall layer 211 facing away from the substrate base plate 10; the modified film is patterned, a modified layer 212 is formed on the exposed surface of the partition wall layer 211, and the modified film at other positions is removed, as shown in fig. 6b, and fig. 6b is a schematic view showing the C-C cross-section structure of the substrate after the modified layer is formed in fig. 2. The material of the modified layer 212 may include poly (N-isopropyl acrylamide) (PNIPAM). The critical temperature is 30 ℃ to 34 ℃. In one exemplary embodiment, the critical temperature is 32 ℃. The first pixel partition wall 21 includes a partition wall layer 211 and a modified layer 212, and the height of the first pixel partition wall 21 is smaller than the height of the second pixel partition wall 22.

S14: the hole injection layer 321 located in the sub-pixel region 30 is formed using an inkjet printing method. This step may include:

hole injection ink 321' is formed in the subpixel areas by an inkjet printing method. Since the first pixel partition wall 21 has a smaller height, the second pixel partition wall 22 has a larger height, and the liquid level of the hole injection ink is higher than the top surface of the first pixel partition wall 21, so that the hole injection ink 321' in the plurality of sub-pixel regions in the same column are mutually communicated, the ink on both sides of the second pixel partition wall 22 is blocked by the second pixel partition wall 22, as shown in fig. 7a and 7b, fig. 7a is a schematic top view structure diagram after the hole injection ink is inkjet printed in the display substrate, and fig. 7b is a schematic D-D cross-sectional structure diagram in fig. 7 a. In the ink-jet printing process, the temperature of the substrate is lower than the critical temperature of the modification layer, and the modification layer is in a lyophilic state and cannot influence the ink communication between adjacent sub-pixel areas. On the same column, the inks in two adjacent sub-pixel areas are communicated, which helps to improve the film formation uniformity of the sub-pixel areas.

The hole injection ink 321' is cured to form a hole injection layer. In the curing process, as the solvent volatilizes during the drying process, the substrate temperature is changed, so that the substrate temperature rises to reach the critical temperature of the modified layer 212, and the modified layer 212 is changed from the lyophobic property to the lyophobic property. The modified layer with lyophobic property limits the ink in the adjacent sub-pixel areas in the same column to form a film in the respective sub-pixel areas, so that crosstalk between the sub-pixels is prevented. The hole injection layer formed finally has better film thickness uniformity, and the luminous quality of the display device is improved.

Other film layers of the light emitting structure layer, for example, a hole transporting layer, an organic light emitting layer, an electron injecting layer, etc., are sequentially formed by an inkjet printing method.

S15: a second electrode 33 is formed on a side of the light emitting structure layer 32 remote from the substrate. The second electrode 33 may be formed using a conventional technique in the art, and will not be described here. The material of the second electrode 33 may be a transparent conductive material, for example, indium tin oxide or indium zinc oxide.

In an exemplary embodiment, the manufacturing process of the display substrate may further include forming a package structure layer on a side of the second electrode 33 facing away from the substrate 10.

In one exemplary embodiment, S13: a pixel defining layer 20 is formed on a side of the first electrode 31 facing away from the substrate 10. The pixel defining layer 20 includes a first pixel partition wall 21 and a second pixel partition wall 22. The first pixel partition walls 21 extend in the first direction X, and the second pixel partition walls 22 extend in the second direction Y. The first pixel partition wall 21 and the second pixel partition wall 22 define a sub-pixel region 30. The height of the first pixel partition wall 21 is smaller than the height of the second pixel partition wall 22. This step may include:

s1321: a partition wall layer 211 is formed at a side of the first electrode 31 facing away from the substrate 10, and the partition wall layer 211 is located between adjacent two of the first electrodes 31 and extends in the first direction. This step may include: forming a first partition film on a side of the first electrode 31 facing away from the substrate 10; and patterning the first partition film by using a single tone mask, reserving the partition layer 211 formed by the first partition film at the position of the partition layer 211, and removing the first partition film at other positions.

S1322: a modification layer 212 is formed on a side of the partition wall layer 211 facing away from the base substrate 10, and when the temperature is greater than or equal to the critical temperature, the modification layer 212 changes from a lyophile property to a lyophobic property. This step may include: forming a modified thin film on a side of the partition wall layer 211 facing away from the substrate base plate 10; the modified film is patterned, and the modified film is left on the exposed surface of the barrier layer 211 to form a modified layer 212, and the modified film at other positions is removed. The material of the modified layer 212 may include poly (N-isopropyl acrylamide) (PNIPAM). The critical temperature is 30 ℃ to 34 ℃. In one exemplary embodiment, the critical temperature is 32 ℃. The first pixel partition 21 includes a partition layer 211 and a modifying layer 212.

S1323: a second pixel partition wall 22 is formed at a side of the modification layer 212 facing away from the substrate 10, the second pixel partition wall 22 is located between two adjacent first electrodes 31 and extends along a second direction, the height of the first pixel partition wall 21 is smaller than that of the second pixel partition wall 22, the first pixel partition wall 21 and the second pixel partition wall 22 define a sub-pixel region 30, the size of the sub-pixel region 30 in the second direction is larger than that of the first electrode 31 corresponding to the sub-pixel region 30. This step may include: forming a second partition film on a side of the modified layer 212 facing away from the substrate 10; and (3) carrying out patterning treatment on the second partition film by adopting a single tone mask, reserving the second partition film at the position of the second pixel partition 22 to form the second pixel partition 22, and removing the second partition films at other positions.

Before solidification, the display substrate formed by the method provided by the embodiment of the invention is communicated with the ink in a plurality of sub-pixel areas in the same column, so that uneven film formation caused by inconsistent volume sprayed by each nozzle can be avoided, and the sub-pixels in the same column can form uniform film; in the curing process, the temperature of the display substrate is raised to reach the critical temperature, so that the modification layer 212 is changed from the lyophile property to the lyophobic property, and therefore, the surface of the first pixel partition wall 21 becomes lyophobic, and the inks on both sides of the first pixel partition wall 21 are gradually limited in the corresponding sub-pixel regions to form a film, so that crosstalk between sub-pixels in the same column is prevented, and the light emitting quality of the display device is improved.

Fig. 8 is a schematic top view of a display substrate according to an exemplary embodiment of the present invention, fig. 9 is a schematic cross-sectional E-E view of fig. 8, and fig. 10 is a schematic cross-sectional F-F view of fig. 8. In one exemplary embodiment, as shown in fig. 8, 9 and 10, the display substrate includes a substrate base 10, and a pixel defining layer 50 disposed at one side of the substrate base 10. The pixel defining layer 50 includes a first wall 51 and a second wall 52. The first wall 51 defines a pixel region, and the second wall 52 is located in the pixel region and defines a plurality of sub-pixel regions 30. In one pixel region, a channel 521 is provided between at least one second barrier wall 52 and the substrate 10 such that sub-pixel regions located at both sides of the channel 521 communicate through the channel 521. The display substrate further comprises a light emitting structure layer disposed on a side of the pixel defining layer 20 facing away from the substrate and located in the sub-pixel region. The light emitting structure layer includes a hole injection layer 321, and when hole injection ink is formed in the sub-pixel region at one side of the channel 521 by using an inkjet printing method, the hole injection ink in the sub-pixel regions at two sides of the channel 521 are communicated.

When the display film layer in the sub-pixel region is formed by the inkjet printing method, since the display film layer in the sub-pixel region is thin, the required ink amount is small, and sometimes the required ink amount for one sub-pixel region is less than 1 drop, it is difficult to perform inkjet printing in the sub-pixel region. To achieve ink jet printing in the sub-pixel area, the ink or jet head needs to be replaced to meet the ink demand of the sub-pixel area. In the display substrate of the embodiment of the invention, a channel 521 is disposed between at least one second retaining wall 52 and the substrate 10 in a pixel region, so that sub-pixel regions located at two sides of the channel 521 are communicated through the channel 521. Therefore, when the common film layer (such as the hole injection layer or the hole transport layer) is printed in the sub-pixel area at one side of the channel 521, the ink for the ink-jet printing can flow to the adjacent sub-pixel area through the channel 521, so that the ink quantity requirement of the sub-pixel area is met, the ink quantity requirement of the nozzle is increased, the nozzle can realize normal printing, the replacement of the ink or the nozzle is avoided, and the ink-jet printing of the sub-pixel areas at two sides of the channel 521 is finished, thereby simplifying the process and being beneficial to realizing mass production.

Fig. 11 is a schematic E-E sectional structure of the display substrate shown in fig. 8 in an exemplary embodiment, and fig. 12 is a schematic F-F sectional structure of the display substrate shown in fig. 8 in an exemplary embodiment. In one exemplary embodiment, as shown in fig. 11 and 12, the height of the channels 521 is less than or equal to the film thickness of the hole injection layer 321.

As will be appreciated by those skilled in the art, the hole injection layer 321 is a common layer when the OLED device is formed by ink jet printing. The height of the channel 521 is set to be smaller than or equal to the film thickness of the hole injection layer 321, so that when the hole injection ink is jet-printed in the sub-pixel area on one side of the channel 521, the hole injection ink can flow to the sub-pixel area on the other side through the channel 521, so that excessive hole injection ink quantity in the sub-pixel area on the printing side is avoided, and meanwhile, the hole injection ink is formed in the sub-pixel area on the other side, and the jet printing is not required in the sub-pixel area on the other side, so that a nozzle with smaller ink output quantity is not required to be replaced, and the process is simplified.

In one exemplary embodiment, the light emitting structure layer 32 may further include a hole transport layer 322 disposed at a side of the hole injection layer 321 facing away from the substrate base plate 10. The height d3 of the channel 521 is greater than or equal to the film thickness of the hole injection layer 321, and the height d3 of the channel 521 is less than or equal to the sum of the film thicknesses of the hole injection layer 321 and the hole transport layer 322.

Those skilled in the art will appreciate that in the case of ink jet printing to form an OLED device, the hole injection layer 321 and the hole transport layer 322 may both be a common layer. The height d3 of the channel 521 is set to be greater than or equal to the thickness of the film of the hole injection layer 321 and less than or equal to the sum of the thicknesses of the film of the hole injection layer 321 and the film of the hole transport layer 322, so that when the hole injection ink is inkjet printed in the sub-pixel area on one side of the channel 521, the hole injection ink can flow to the sub-pixel area on the other side through the channel 521, not only the excessive amount of the hole injection ink in the sub-pixel area on the printing side is avoided, but also the hole injection ink is formed in the sub-pixel area on the other side, and the inkjet printing in the sub-pixel area on the other side is not required, so that a nozzle with smaller ink outlet amount is not required to be replaced, and the process is simplified. In addition, when the hole transport ink is printed in the ink-jet manner in the sub-pixel region on one side of the channel 521, the hole transport ink can flow to the sub-pixel region on the other side through the channel 521, so that not only is the excessive amount of the hole transport ink avoided in the sub-pixel region on the printing side, but also the hole transport ink is formed in the sub-pixel region on the other side, and the ink-jet printing is not required in the sub-pixel region on the other side, so that the nozzle with smaller ink outlet amount is not required to be replaced, and the process is simplified.

The height d3 of the channel 521 is less than or equal to the sum of the thicknesses of the hole injection layer 321 and the hole transport layer 322, so that after the hole transport ink is cured to form the hole transport layer, the channel 521 is filled and the sub-pixel regions on both sides of the channel 521 are divided. Thus, when the organic light emitting ink is printed later, the organic light emitting ink in the sub-pixel region on one side of the channel 521 no longer flows into the sub-pixel region on the other side, so that separate printing of the organic light emitting ink in each sub-pixel region can be realized, and color printing can be realized.

In an exemplary embodiment, as shown in fig. 9, in the extending direction of the second retaining wall 52, the orthographic projection boundary of the channel 521 on the substrate 10 is located within the orthographic projection boundary of the second retaining wall 52 on the substrate 10, so that the second retaining wall 52 has an arch structure, and the two ends of the second retaining wall 52 are supported, which increases the structural strength of the second retaining wall 52.

In one exemplary embodiment, as shown in fig. 8, the pixel region includes three sub-pixel regions, respectively a red sub-pixel region, a green sub-pixel region, and a blue sub-pixel region. The channel 521 is disposed between the second barrier wall 52 between the red and green sub-pixel regions and the substrate 10.

For a full print top emission display product, its resolution is 160ppi, the subpixel size can be 31.9 μm 107.8 μm, and the aperture ratio 38.3%. Through simulation calculation, in the top emission display product, the thickness of the Hole Injection Layer (HIL) required in the red sub-pixel and the green sub-pixel is 10nm, the volume of the required ink is 2.7pl, the ink quantity is less than 1 drop for a 10pl nozzle of G2.5, and the 10pl nozzle of G2.5 is difficult to prepare the light emitting devices of the red sub-pixel and the green sub-pixel. The channel 521 is disposed between the second barrier wall 52 and the substrate 10 between the red sub-pixel region and the green sub-pixel region, so that when the hole injection ink is inkjet-printed to the red sub-pixel region, the hole injection ink can flow to the green sub-pixel region through the channel 521, increasing the amount of ink, so that the hole injection ink can be inkjet-printed using 10pl of G2.5, the replacement of the nozzle is not required, and the hole injection layers of the red sub-pixel region and the green sub-pixel region can be simultaneously formed, simplifying the process, and facilitating mass production.

In one exemplary embodiment, as shown in fig. 10, the display substrate may further include a plurality of first electrodes 31, the first electrodes 31 being located between the substrate 10 and the pixel defining layer 50, the first electrodes 31 being located in the sub-pixel regions, the first electrodes 31 being disposed corresponding to the sub-pixel regions. The first electrode 31 may be an anode. In the top-emitting OLED display substrate, the material of the first electrode 31 may be a conductive material having a light reflecting effect, such as magnesium aluminum alloy, magnesium silver alloy, calcium silver alloy, or the like. In the bottom-emission or double-emission OLED display substrate, the material of the first electrode 31 may be a conductive material having a light-transmitting effect, such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO), or the like.

In an exemplary embodiment, the light emitting structure layer may further include a film layer such as an organic light emitting layer, an electron injection layer, and the like sequentially stacked on a side of the hole transport layer facing away from the substrate. The display substrate may further include a second electrode disposed on a side of the light emitting structure layer facing away from the substrate, the second electrode may be a cathode, and a material of the second electrode may be a transparent conductive material, for example, indium tin oxide or indium zinc oxide. In one exemplary embodiment, the display substrate may further include a package structure layer disposed at a side of the second electrode facing away from the substrate.

In one exemplary embodiment, S1 may include:

and removing the sacrificial layer to form a channel, wherein the sub-pixel areas at two sides of the channel are communicated through the channel.

In one exemplary embodiment, S2 may include:

The technical scheme of the display substrate shown in fig. 8 according to the embodiment of the invention is described in detail below through the preparation process of the display substrate. It is to be understood that, in the present embodiment, the "patterning" includes processes of coating photoresist, mask exposure, developing, etching, stripping photoresist, etc. when the patterned material is inorganic material or metal, and processes of mask exposure, developing, etc. when the patterned material is organic material, the "patterning" includes processes of evaporation, deposition, coating, etc. in the present embodiment, all processes are mature preparation processes in the related art.

S21: a substrate base 10 is provided. As will be appreciated by those skilled in the art, the substrate base 10 may include a substrate and a thin film transistor array layer disposed on one side of the substrate.

S22: a plurality of first electrodes 31 are formed on one side of the substrate 10, and the plurality of first electrodes 31 are arranged in an array. The first electrode 31 may be formed using a conventional technique in the art, and will not be described herein.

S23: the surface of the first electrode 31 is lyophobic. CF can be used ₄ The solution performs lyophobic treatment on the surface of the first electrode 31, so that the surface of the first electrode 31 has lyophobicity.

S24: in a pixel region, a water-soluble polymer solution is printed between the first electrodes corresponding to the red sub-pixel region and the green sub-pixel region respectively, and after the water-soluble polymer solution is solidified, a sacrificial layer is formed between the two first electrodes, as shown in fig. 13, and fig. 13 is a schematic diagram showing a cross-sectional structure of the F-F after the sacrificial layer is formed in the substrate. The material of the sacrificial layer 60 may be a water-soluble polymer material, such as polyacrylamide, and the height of the sacrificial layer 60 is greater than the height of the first electrode 31.

S25: the pixel defining layer 50 is formed on a side of the sacrificial layer 60 facing away from the substrate base plate 10. This step may include: forming a pixel defining film on a side of the sacrificial layer 60 facing away from the substrate base plate 10; the pixel defining film is patterned, and a first retaining wall 51 and a second retaining wall 52 are respectively formed between two adjacent columns and two adjacent rows, the first retaining wall 51 defines a pixel region, the second retaining wall 52 is located in the pixel region and defines a plurality of sub-pixel regions 30, as shown in fig. 8 and 14, and fig. 14 is a schematic diagram showing an F-F cross-section structure after the second retaining wall is formed in the substrate. Wherein, the first retaining wall and the second retaining wall can be made of resin, silicon oxide or organic silicon.

S26: the sacrificial layer 60 is removed to form a via 521, as shown in fig. 10. This step may include: the sacrificial layer 60 is dissolved and removed by water dissolution to form a channel 521 connecting the red sub-pixel region and the green sub-pixel region. Wherein the height d3 of the channel 521 is greater than or equal to the film thickness of the hole injection layer 321, and the height d3 of the channel 521 is less than or equal to the sum of the film thicknesses of the hole injection layer 321 and the hole transport layer 322.

S27: and forming a hole injection layer of the red sub-pixel region and the green sub-pixel region simultaneously. This step may include: the hole injection ink 321 'is printed in the red sub-pixel region or the green sub-pixel region in an inkjet manner, the hole injection ink 321' flows between the red sub-pixel region and the green sub-pixel region and fills the red sub-pixel region and the green sub-pixel region, as shown in fig. 15, fig. 15 is a schematic diagram of a cross-section F-F structure of the display substrate after the hole injection ink is printed in the red sub-pixel region or the green sub-pixel region in an inkjet manner; the hole injection ink is cured to form the hole injection layer 321 in the red sub-pixel region and the green sub-pixel region, as shown in fig. 16, and fig. 16 is a schematic view showing the F-F cross-section structure of the substrate after the hole injection layer is formed in the red sub-pixel region and the green sub-pixel region.

S28: the hole transport layers of the red and green sub-pixel regions are simultaneously formed. This step may include: the hole transport ink 322 'is ink-jet printed in the red sub-pixel region or the green sub-pixel region, the hole transport ink 322' flows between the red sub-pixel region and the green sub-pixel region, and fills the red sub-pixel region and the green sub-pixel region, as shown in fig. 17, fig. 17 is a schematic diagram of the F-F cross-section structure of the display substrate after the hole transport ink is ink-jet printed in the red sub-pixel region or the green sub-pixel region; the hole transport ink is cured to form the hole transport layer 322 of both the red and green sub-pixel regions as shown in fig. 12.

Finally, film layers such as an organic light-emitting layer, an electron injection layer and the like are formed in each sub-pixel region through ink-jet printing, and a second electrode and a packaging structure layer are sequentially formed on one side, away from the substrate, of the light-emitting structure layer.

The embodiment of the invention also provides a display device, which comprises the display substrate adopting the embodiment. The display device may be: any product or component with display function such as a mobile phone, a tablet computer, a television, a display, a notebook computer, a digital photo frame, a navigator and the like.

In the description of the embodiments of the present invention, it should be understood that the terms "middle," "upper," "lower," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, merely to facilitate description of the present invention and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.

In describing embodiments of the present invention, it should be noted that, unless explicitly stated and limited otherwise, the terms "mounted," "connected," and "connected" should be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.

Although the embodiments of the present invention are described above, the embodiments are only used for facilitating understanding of the present invention, and are not intended to limit the present invention. Any person skilled in the art can make any modification and variation in form and detail without departing from the spirit and scope of the present disclosure, but the scope of the present disclosure is to be determined by the appended claims.

Claims

1. A display substrate, comprising:

a substrate base;

the pixel defining layer is arranged on one side of the substrate base plate and defines a plurality of sub-pixel areas; the pixel defining layer comprises a first retaining wall and a second retaining wall, wherein the first retaining wall is used for defining a pixel area, the second retaining wall is positioned in the first retaining wall and is used for defining sub-pixel areas, a channel is arranged between at least one second retaining wall and the substrate base plate in the pixel area, and the sub-pixel areas positioned at two sides of the channel are communicated through the channel; the method comprises the steps of,

the light-emitting structure layer is arranged on one side of the pixel defining layer, which is away from the substrate base plate, and is positioned in the sub-pixel area, the light-emitting structure layer comprises a hole injection layer, when hole injection ink is formed in the sub-pixel area on one side of the channel by adopting an ink-jet printing method, the hole injection ink in the sub-pixel area on two sides of the channel is communicated, the height of the channel is smaller than or equal to the thickness of the film layer of the hole injection layer, and the hole injection layer in the sub-pixel area on two sides of the channel is communicated through the channel.

2. The display substrate according to claim 1, wherein the light emitting structure layer further comprises a hole transport layer disposed on a side of the hole injection layer facing away from the substrate, the height of the channel is greater than or equal to the film thickness of the hole injection layer, the height of the channel is less than or equal to the sum of the film thicknesses of the hole transport layer and the hole injection layer, and the hole injection layer and the hole transport layer of the sub-pixel region disposed on both sides of the channel are all communicated through the channel.

3. A display substrate according to claim 1 or 2, wherein the pixel region comprises a red sub-pixel region and a green sub-pixel region, the channel being located between the red sub-pixel region and the green sub-pixel region.

4. A method for manufacturing a display substrate, comprising:

forming a pixel defining layer on one side of a substrate base plate, wherein the pixel defining layer defines a plurality of sub-pixel areas; comprising the following steps: the substrate comprises a pixel region, wherein the pixel region comprises a plurality of sub-pixel regions, and a sacrificial layer is formed between at least two adjacent sub-pixel regions in one pixel region; forming a first retaining wall and a second retaining wall on one side of the sacrificial layer, which is away from the substrate, wherein the first retaining wall is positioned between adjacent pixel areas, and the second retaining wall is positioned between adjacent sub-pixel areas in the first retaining wall; removing the sacrificial layer to form a channel, wherein the sub-pixel areas at two sides of the channel are communicated through the channel;

ink-jet printing hole injection ink on the side of the pixel defining layer facing away from the substrate base plate, wherein the hole injection ink of at least two adjacent sub-pixel areas is communicated, and the ink-jet printing hole injection ink comprises the following components: and (3) carrying out ink jet printing on the sub-pixel areas at one side of the channel to form hole injection ink, wherein the hole transport ink flows between the sub-pixel areas at two sides of the channel to fill the sub-pixel areas at two sides of the channel.

5. A display device comprising the display substrate according to any one of claims 1 to 3.