CN111463353A

CN111463353A - Display substrate, preparation method thereof and display device

Info

Publication number: CN111463353A
Application number: CN202010202661.8A
Authority: CN
Inventors: 崔颖; 侯文军
Original assignee: Zhejiang Luyuan Electric Vehicle Co Ltd
Current assignee: Zhejiang Luyuan Electric Vehicle Co Ltd
Priority date: 2020-03-20
Filing date: 2020-03-20
Publication date: 2020-07-28
Anticipated expiration: 2040-03-20
Also published as: CN111463353B

Abstract

The invention discloses a display substrate, a preparation method thereof and a display device. A display substrate, comprising: a substrate base plate; a pixel defining layer disposed at one side of the substrate base plate, the pixel defining layer defining a plurality of sub-pixel regions; and the light emitting structure layer is arranged on one side of the pixel defining layer, which is far away from the substrate and is positioned in the sub-pixel region, the light emitting structure layer comprises a hole injection layer, and when 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 make the hole injection layer film thickness of at least two adjacent sub-pixel regions uniform, reduce the film thickness difference between sub-pixels and improve the brightness uniformity between 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

Organic light Emitting Diode (O L ED) display substrates are widely used in the display fields of mobile phones, tablet computers, digital cameras, etc. due to their advantages of low energy consumption, low production cost, self-luminescence, wide viewing angle, and fast response speed.

At present, the O L ED device can be formed by an ink-jet printing method, however, an error in the amount of ink ejected among a plurality of nozzles causes non-uniformity in film thickness among sub-pixels, resulting in a difference in brightness uniformity among pixels.

Disclosure of Invention

An object of an embodiment of the present invention is to provide a display substrate to improve the uniformity of the sub-pixel film thickness.

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

a substrate base plate;

a pixel defining layer disposed at one side of the substrate base plate, the pixel defining layer defining a plurality of sub-pixel regions; and the number of the first and second groups,

the light emitting structure layer is arranged on one side, away from the substrate, of the pixel defining layer and is positioned in the sub-pixel region, the light emitting structure layer comprises a hole injection layer, and when 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.

In some of the possible implementations of the present invention,

the pixel defining layer includes first pixel partition walls extending in a first direction and second pixel partition walls extending in a second direction, the first and second pixel partition walls intersecting to define the sub-pixel regions, the first pixel partition walls having a height smaller than that of the second pixel partition walls, the first and second directions being perpendicular to each other, the sub-pixel regions having a size in the first direction smaller than that in the second direction,

when the ink for injecting the holes is formed in the sub-pixel areas by adopting an ink-jet printing method, the ink for injecting the holes of the plurality of sub-pixel areas positioned between two adjacent second pixel partition walls is communicated.

In some possible implementations, the height of the first pixel partition is 0.1 μm to 0.8 μm, and the height of the second pixel partition is 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 surface of the partition layer facing away from the substrate, where the modification layer changes from a lyophilic characteristic to a lyophobic characteristic when a temperature is greater than or equal to a critical temperature.

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

In some possible implementations, the material of the modification 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 in 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 at both sides of the channel are communicated through the channel,

when the ink-jet printing method is adopted to form the hole injection ink in the sub-pixel area on one side of the channel, the hole injection ink in the sub-pixel areas on the two sides of the channel is 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 on both sides of the channel are communicated through the channel.

In some possible implementation manners, the light emitting structure layer further includes a hole transport layer disposed on a side of the hole injection layer away from the substrate, the height of the channel is greater than or equal to the thickness of the film layer of the hole injection layer, the height of the channel is less than or equal to the sum of the thicknesses of the film layer of the hole transport layer and the film layer of the hole injection layer, and the hole injection layer and the hole transport layer in the sub-pixel regions on both sides of the channel are both 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 problem, 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, the pixel defining layer defining a plurality of sub-pixel regions;

and ink-jet printing hole injection ink on the side of the pixel defining layer, which is far away from the substrate, wherein the hole injection ink of at least two adjacent sub-pixel regions is communicated.

In some of the possible implementations of the present invention,

the forming of a pixel defining layer on one side of a substrate, the pixel defining layer defining a plurality of sub-pixel regions, includes:

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 crossed 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 perpendicular to each other, and the size of the sub-pixel region in the first direction is smaller than that in the second direction;

forming a modification layer on one side of the partition wall layer, which is far away from the substrate base plate, wherein when the temperature is higher than or equal to a critical temperature, the modification layer is changed from lyophilic characteristics to lyophobic characteristics, the first pixel partition wall comprises a partition wall layer and a line changing layer which are stacked, the height of the first pixel partition wall is smaller than that of the second pixel partition wall,

the ink-jet printing hole injection ink on the side of the pixel defining layer away from the substrate comprises:

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

and curing the hole injection ink, wherein the modified layer is changed from lyophilic to lyophobic, and the hole injection ink on two sides of the first pixel partition wall is limited in the corresponding sub-pixel region to form a film.

In some of the possible implementations of the present invention,

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

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

and ink-jet printing hole injection ink in the sub-pixel area on one side of the channel, wherein the hole transmission ink flows between the sub-pixel areas on two sides of the channel to fill the sub-pixel areas on two sides of the channel.

In order to solve the above technical problem, an embodiment of the present invention further provides a display device, including the display panel described above.

According to the display substrate provided by the embodiment of the invention, 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. Therefore, the at least two adjacent sub-pixel regions which are communicated can form uniform hole injection ink, so that the hole injection layer film thickness of the at least two adjacent sub-pixel regions is uniform, the film thickness difference among the sub-pixels is reduced, and the brightness uniformity among 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 on the spray head is increased, the spray head with small ink output does not need to be replaced, the time consumption for replacing the spray head is avoided, a hole injection layer can be formed in the at least two adjacent sub-pixel areas simultaneously, 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 embodiments of the invention and together with the example serve to explain the principles of the invention and not to limit the invention.

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

FIG. 1b is a schematic diagram 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 in 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 cross-sectional view taken along line B-B of FIG. 2;

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

FIG. 6a is a schematic view of a cross-sectional view of the substrate shown in FIG. 2 after forming a spacer layer thereon;

FIG. 6b is a schematic view of the cross-sectional structure of the substrate shown in FIG. 2 after a modified layer is formed thereon;

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

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

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

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

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

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

FIG. 12 is a schematic view of 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 a cross-sectional structure of F-F after a sacrificial layer is formed in a substrate;

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

FIG. 15 is a schematic view showing a cross-sectional structure of F-F after ink is injected by ink-jet printing holes in a red sub-pixel region or a green sub-pixel region of a substrate;

FIG. 16 is a schematic view showing a cross-sectional structure of F-F after hole injection layers are formed in the red and green sub-pixel regions of the display substrate;

fig. 17 is a schematic view showing a cross-sectional structure of F-F after hole transport ink is inkjet printed in a red sub-pixel region or a green sub-pixel region in a substrate.

Description of reference numerals:

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

211-partition wall layer; 212 — a modified layer; 22 — second pixel partition;

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

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

521-a sacrificial layer; 60-sacrificial layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.

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

When an O L ED device is manufactured by adopting an ink-jet printing method, due to the error of ink-jet quantity among a plurality of nozzles, the thickness of a display film layer among sub-pixels is not uniform easily, and the brightness uniformity among pixels is different.

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

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

For a full-print top-emission display product with a resolution of 160ppi, a subpixel size of 31.9 μm 107.8 μm, and an aperture ratio of 38.3%, the required thickness of the hole injection layer (HI L) was 10nm, the required ink volume was 2.7pl, and the ink amount was less than 1 drop for a 10pl nozzle of G2.5 in the top-emission display product, the red and green subpixels, and thus it was difficult to fabricate light emitting devices for the red and green subpixels using the 10pl nozzle of G2.5.

In order to solve the above technical problem, an embodiment of the present invention provides a display substrate. The display substrate includes: a substrate base plate; a pixel defining layer disposed at one side of the substrate base plate, the pixel defining layer defining a plurality of sub-pixel regions; and the light emitting structure layer is arranged on one side of the pixel defining layer, which is far away from the substrate and is positioned in the sub-pixel region, the light emitting structure layer comprises a hole injection layer, and when 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 specific embodiments.

Fig. 2 is a schematic top view, fig. 3 is a schematic cross-sectional view a-a in fig. 2, and fig. 4 is a schematic cross-sectional view B-B in fig. 2, illustrating a display substrate according to an exemplary embodiment of the present invention. In one exemplary embodiment, as shown in fig. 2, 3 and 4, the display substrate includes a substrate base plate 10 and a pixel defining layer 20 disposed at one side of the substrate base plate 10. The pixel defining layer 20 includes first and second

pixel partition walls

21 and 22. The first pixel partition walls 21 extend in a first direction X (a row direction in fig. 2), and the second pixel partition walls 22 extend in a second direction Y (a column direction in fig. 2). The first pixel partition walls 21 and the second pixel partition walls 22 intersect to define sub-pixel regions 30. The height of the first pixel partition walls 21 is smaller than the height of the second pixel partition walls 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 the direction perpendicular to the substrate base plate. The display substrate further includes a light emitting structure layer disposed on a side of the pixel defining layer 20 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 regions by using an inkjet printing method, the hole injection ink in the plurality of sub-pixel regions located between two adjacent second pixel partitions 22 is communicated.

In the display substrate according to the embodiment of the present invention, when the hole injection ink is formed by the inkjet printing method, before curing, 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. Thus, the liquid ink can be communicated between the plurality of sub-pixel regions located between two adjacent second pixel partitions 22, that is, the inks of the plurality of sub-pixel regions located in the same column are communicated with each other. Therefore, uneven film formation caused by inconsistent ejection volumes of all the nozzles can be avoided, so that the sub-pixels in the same row can be formed uniformly, and the light emitting 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 21 is 0.1 μm to 0.8 μm, and the height d2 of the second pixel partition 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 on 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 the critical temperature, the modification layer 212 is changed from the lyophilic characteristic to the lyophobic characteristic. In one exemplary embodiment, the modification layer 212 is located on the surface of the partition layer 211 on the side away from the substrate base plate, that is, the modification layer 212 is located on the top surface of the partition layer 211. The lyophilic properties of the modified layer 212 facilitate communication between sub-pixel regions in the same column when printing ink. In the process of curing the ink, the temperature of the display substrate may rise to reach a critical temperature, so that the modification layer 212 is changed from lyophilic to lyophobic, and thus the top surface of the first pixel partition wall 21 becomes lyophobic, and the ink on both sides of the first pixel partition wall 21 in the same column is gradually limited in the corresponding sub-pixel region, thereby preventing crosstalk between sub-pixels.

In an exemplary embodiment, the modification layer 212 covers the exposed surface of the partition wall layer 211, that is, the modification layer 212 is located on the surface of the partition wall layer 211 on the side away from the substrate base plate 10 and on the sidewall surfaces on both sides of the partition wall layer 211, as shown in fig. 3. In the ink curing process, the modification layer 212 is changed from lyophilic to lyophobic, 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 close to the first pixel partition wall 21 after film forming is prevented from being too large, and the film thickness uniformity of the sub-pixel region is further improved.

In an exemplary embodiment, the material of the modified layer 212 may include poly (N-isopropylacrylamide) (PNIPAM). It will be understood by those skilled in the art that the material of the modified layer 212 is not limited to poly (N-isopropylacrylamide), and can be selected to produce a modified layer as long as the lyophilic and lyophobic properties of the material can be changed 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 21 is located between the substrate 10 and the pixel defining layer 20, the first electrode 21 is located in the sub-pixel region 30, the first electrode 21 may be an anode, in the top emission O L ED display substrate, the material of the first electrode 21 may be a conductive material having a light reflecting function, such as magnesium aluminum alloy, magnesium silver alloy, or calcium silver alloy, etc., in the bottom emission or dual emission O L ED display substrate, the material of the first electrode 21 may be a conductive material having a light transmitting function, such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO), etc.

FIG. 5 is a schematic cross-sectional view 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 away from the substrate. In one exemplary embodiment, the display substrate may further include a second electrode 33 disposed at a side of the light emitting structure layer away from the base substrate 10, and the second electrode may be a cathode. In an exemplary embodiment, the display substrate may further include an encapsulation structure layer disposed on a side of the second electrode 33 facing away from the substrate 10.

Each film layer of the light emitting structure layer may be formed by inkjet printing. When each film layer of the light-emitting structure layer is formed in the sub-pixel area by adopting an ink-jet printing method, before the film layers are cured, ink among the sub-pixel areas in the same row is communicated, and the second pixel partition walls block the ink from flowing to other rows. Therefore, uneven film formation caused by inconsistent ejection volumes of all nozzles is avoided, the film thickness of the light-emitting structure layers on the same row 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, the pixel defining layer defining a plurality of sub-pixel regions;

s2: and ink-jet printing hole injection ink on the side of the pixel defining layer, which is far away from the substrate, wherein the hole injection ink of at least two adjacent sub-pixel regions is communicated.

In an exemplary embodiment, S1 may include:

the side of the partition wall layer departing from the substrate base plate is provided with a modified layer, when the temperature is higher than or equal to the critical temperature, the modified layer is changed into lyophobic property from lyophilic property, 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 an exemplary embodiment, S2 may include:

The following describes the technical solution of the display substrate shown in fig. 2 in the embodiment of the present invention in detail through the preparation process of the display substrate. It is to be understood that "patterning" in this embodiment includes processes of coating photoresist, mask exposure, development, etching, stripping photoresist, etc. when the material to be patterned is an inorganic material or a metal, and includes processes of mask exposure, development, etc. when the material to be patterned is an organic material, and evaporation, deposition, coating, etc. in this embodiment are well-established preparation processes in the related art.

S11: a base substrate 10 is provided. As will be understood by those skilled in the art, the substrate base plate 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 base plate 10, and the plurality of first electrodes 31 are arranged in an array. The first electrode 31 may be formed using techniques conventional in the art and will not be described in detail herein.

S13: the pixel defining layer 20 is formed on a side of the first electrode 31 facing away from the base substrate 10. The pixel defining layer 20 includes a first pixel partition 21 and a second pixel partition 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 walls 21 and the second pixel partition walls 22 define sub-pixel regions 30. The height of the first pixel partition walls 21 is smaller than the height of the second pixel partition walls 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 patterning process, the partition wall layer 211 is located between two adjacent first electrodes 31 and extends along a first direction, the second pixel partition wall 22 is located 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 area 30, the size of the sub-pixel area 30 in the second direction is larger than that in the first direction, and the first electrodes 31 correspond to the sub-pixel area 30. This step may include: forming a partition wall film on a side of the first electrode 31 facing away from the substrate base plate 10; the partition wall thin film is patterned by using a gray-tone mask, the partition wall layer 211 formed by retaining a partial thickness of the partition wall thin film at the position of the partition wall layer 211, the partition wall thin film formed by retaining the entire thickness of the partition wall thin film at the position of the second pixel partition wall 22, and the partition wall thin films at other positions are removed, as shown in fig. 6a, fig. 6a is a schematic view of a C-C cross-sectional structure of the display substrate after the partition wall 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 and second directions 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. The material of the partition wall film can be resin, organic silicon or silicon dioxide.

S1312: the modification layer 212 is formed on the side of the partition wall layer 211 away from the substrate base plate 10, and when the temperature is greater than or equal to the critical temperature, the modification layer 212 is changed from lyophilic to lyophobic. This step may include: forming a modified film on the side of the partition wall layer 211 departing from the substrate base plate 10; the modified film is patterned to form a modified layer 212 on the exposed surface of the partition layer 211, and the modified film at other positions is removed, as shown in fig. 6b, where fig. 6b is a schematic view of a C-C cross-sectional structure of the substrate shown in fig. 2 after the modified layer is formed. The material of the modified layer 212 may include poly (N-isopropylacrylamide) (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 modification layer 212, and the height of the first pixel partition wall 21 is smaller than that of the second pixel partition wall 22.

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

the hole injecting ink 321' is formed in the sub-pixel region by an ink jet printing method. Since the height of the first pixel partition wall 21 is small, the height of the second pixel partition wall 22 is large, 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 inks 321' in the plurality of sub-pixel regions in the same column are communicated with each other, and the inks on both sides of the second pixel partition wall 22 are blocked by the second pixel partition wall 22, as shown in fig. 7a and 7b, fig. 7a is a schematic top view structure diagram showing the ink injection of the hole injection ink after the ink injection is performed by the inkjet printing in the substrate, and fig. 7b is a schematic D-D 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, so that ink communication between adjacent sub-pixel areas is not influenced. In the same row, the ink in the adjacent two sub-pixel areas is communicated, which is helpful for improving the film forming uniformity of the sub-pixel areas.

The hole injection ink 321' is cured to form a hole injection layer. In the curing process, the change of the substrate temperature is accompanied with the volatilization of the solvent in the drying process, so that the substrate temperature is increased to reach the critical temperature of the modified layer 212, and the modified layer 212 is changed from lyophilic to lyophobic. The modifying layer with lyophobic property limits the ink in the adjacent sub-pixel areas in the same column to be formed in the sub-pixel areas, thereby preventing the crosstalk between the sub-pixels. The finally formed hole injection layer has better film thickness uniformity, and the light emitting quality of the display device is improved.

Other film layers of the light emitting structure layer, such as a hole transport layer, an organic light emitting layer, an electron injection layer, etc., are sequentially formed by an ink jet printing method.

S15: a second electrode 33 is formed on a side of the light emitting structure layer 32 away from the base substrate. The second electrode 33 may be formed using techniques conventional in the art and will not be described in detail herein. The material of the second electrode 33 may be a transparent conductive material, such as indium tin oxide or indium zinc oxide.

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

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

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

S1322: the modification layer 212 is formed on the side of the partition wall layer 211 away from the substrate base plate 10, and when the temperature is greater than or equal to the critical temperature, the modification layer 212 is changed from lyophilic to lyophobic. This step may include: forming a modified film on the side of the partition wall layer 211 departing from the substrate base plate 10; the modified film is subjected to patterning treatment, the modified film is left on the exposed surface of the partition wall 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-isopropylacrylamide) (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 modification layer 212.

S1323: a second pixel partition wall 22 is formed on a side of the modified layer 212 facing away from the substrate base plate 10, the second pixel partition wall 22 is located between two adjacent first electrodes 31 and extends along the 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 in the first direction, and the first electrodes 31 correspond to the sub-pixel region 30. This step may include: forming a second partition wall film on the side of the modified layer 212 away from the substrate base plate 10; the second partition wall film is patterned using a single tone mask, the second pixel partition walls 22 formed by leaving the second partition wall film at the positions of the second pixel partition walls 22, and the second partition wall films at other positions are removed.

According to the display substrate formed by the method, before solidification, the inks in the plurality of sub-pixel areas in the same row are communicated with each other, so that uneven film formation caused by inconsistent ejection volumes of all nozzles can be avoided, and the sub-pixels in the same row can form a uniform film; in the curing process, the temperature of the display substrate rises to reach the critical temperature, so that the modification layer 212 is changed from lyophilic to lyophobic, the surface of the first pixel partition wall 21 becomes lyophobic, and the ink on the two sides of the first pixel partition wall 21 is gradually limited in the corresponding sub-pixel regions to form a film, thereby preventing crosstalk between sub-pixels in the same column and improving the light emitting quality of the display device.

Fig. 8 is a schematic top view, fig. 9 is a schematic cross-sectional view from E to E in fig. 8, and fig. 10 is a schematic cross-sectional view from F to F in fig. 8, illustrating a display substrate according to an exemplary embodiment of the present invention. In one exemplary embodiment, as shown in fig. 8, 9 and 10, the display substrate includes a substrate base plate 10, and a pixel defining layer 50 disposed at one side of the substrate base plate 10. The pixel defining layer 50 includes first and

second banks

51 and 52. The first wall 51 defines a pixel region, and the second wall 52 is disposed in the pixel region and defines a plurality of sub-pixel regions 30. In one pixel region, a passage 521 is provided between at least one second barrier wall 52 and the substrate base 10, so that sub-pixel regions at both sides of the passage 521 communicate through the passage 521. The display substrate further includes a light emitting structure layer disposed on a side of the pixel defining layer 20 away from the substrate and located in the sub-pixel region. The light emitting structure layer comprises a hole injection layer 321, and when hole injection ink is formed in the sub-pixel region on one side of the channel 521 by adopting an ink jet printing method, the hole injection ink in the sub-pixel regions on two sides of the channel 521 is communicated.

When the display film layer in the sub-pixel region is formed by an ink jet printing method, since the display film layer in the sub-pixel region is thin, the amount of ink required is small, and the amount of ink required for one sub-pixel region is sometimes less than 1 drop, which makes it difficult to perform ink jet printing in the sub-pixel region. In order to realize ink jet printing in the sub-pixel region, the ink or the head needs to be replaced to meet the ink amount requirement of the sub-pixel region. In the display substrate according to the embodiment of the invention, in one pixel region, the channel 521 is disposed between at least one second barrier 52 and the substrate 10, so that the sub-pixel regions at two sides of the channel 521 are communicated through the channel 521. Therefore, when a common film layer (such as a hole injection layer or a hole transmission layer) is printed by ink jet in the sub-pixel area on one side of the channel 521, the ink printed by the ink jet can flow to the adjacent sub-pixel area through the channel 521, not only is the ink quantity requirement of the sub-pixel area met, but also the ink outlet quantity requirement of the nozzle is increased, so that the nozzle can realize normal printing, the ink or the nozzle is prevented from being replaced, the ink jet printing of the sub-pixel areas on the two sides of the channel 521 is simultaneously completed, the process is simplified, and the mass production is favorably realized.

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

It will be understood by those skilled in the art that when inkjet printing is performed to form an O L ED device, the hole injection layer 321 is a common layer, and the height of the channel 521 is set to be less than or equal to the film thickness of the hole injection layer 321, so that when inkjet printing hole injection ink in the sub-pixel region on one side of the channel 521, the hole injection ink can flow to the sub-pixel region on the other side through the channel 521, thereby not only avoiding the excessive amount of hole injection ink in the sub-pixel region on the printing side, but also forming hole injection ink in the sub-pixel region on the other side, and avoiding the need to perform inkjet printing in the sub-pixel region on the other side, and thus eliminating the need to replace a nozzle with a smaller amount of ink, and simplifying the process.

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.

It will be understood by those skilled in the art that when an O L ED device is formed by ink jet printing, the hole injection layer 321 and the hole transport layer 322 may both be a common layer, and 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 ink jet printing is performed in the sub-pixel region on one side of the channel 521, the hole injection ink may flow through the channel 521 to the sub-pixel region on the other side, thereby not only avoiding the need to change the ink jet head with a smaller amount in the sub-pixel region on the printing side, and simplifying the process, but also when ink jet printing is performed in the sub-pixel region on one side of the channel 521, the hole transport ink may flow through the channel 521 to the sub-pixel region on the other side, thereby avoiding the need to change the ink jet head with a smaller amount.

The height d3 of the via 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, so that, after the hole transport ink is cured to form the hole transport layer, the via 521 is filled and the sub-pixel regions on both sides of the via 521 are divided. Therefore, when the organic light-emitting ink is printed subsequently, the organic light-emitting ink in the sub-pixel area on one side of the channel 521 does not flow into the sub-pixel area on the other side, so that the organic light-emitting ink in each sub-pixel area can be printed independently, and the 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 base plate 10 is located within the orthographic projection boundary of the second retaining wall 52 on the substrate base plate 10, so that the second retaining wall 52 has an arch structure, and supports are provided at both ends of the second retaining wall 52, thereby increasing 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, 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 52 between the red and green sub-pixel regions and the substrate base 10.

For a full-print top-emission display product with a resolution of 160ppi, a subpixel size of 31.9 μm 107.8 μm, and an aperture ratio of 38.3%, the top-emission display product, a red subpixel and a green subpixel, in which the required thickness of the hole injection layer (HI L) is 10nm, the required ink volume is 2.7pl, and the ink volume is less than 1 drop for a 10pl nozzle of G2.5, it is difficult to fabricate a light emitting device of the red subpixel and the green subpixel using the 10pl nozzle of G2.5, and the channel 521 is disposed between the second barrier 52 and the substrate 10 between the red subpixel region and the green subpixel region, so that, when ink is injected into the red subpixel region by inkjet printing holes, the hole injection ink can flow to the green subpixel region through the channel 521, increasing the ink volume, so that the 10pl injection of G2.5 can be used, the ink injection does not need to be replaced, and the hole injection can be performed simultaneously with the green subpixel region, which facilitates the mass production process.

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 are disposed between the substrate 10 and the pixel defining layer 50, the first electrodes 31 are disposed in the sub-pixel regions, and the first electrodes 31 correspond to the sub-pixel regions, the first electrodes 31 may be anodes, in the top emission O L ED display substrate, the first electrodes 21 may be made of a conductive material having a light reflection function, such as magnesium aluminum alloy, magnesium silver alloy, or calcium silver alloy, etc. in the bottom emission or dual emission O L ED display substrate, the first electrodes 21 may be made of a conductive material having a light transmission function, such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO).

In an exemplary embodiment, the light emitting structure layer may further include an organic light emitting layer, an electron injection layer, and other film layers 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 the material of the second electrode may be a transparent conductive material, such as indium tin oxide or indium zinc oxide. In an exemplary embodiment, the display substrate may further include an encapsulation structure layer disposed on a side of the second electrode facing away from the substrate.

In an exemplary embodiment, S1 may include:

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

In an exemplary embodiment, S2 may include:

The following describes in detail the technical solution of the display substrate shown in fig. 8 according to the embodiment of the present invention through the process of manufacturing the display substrate. It is to be understood that "patterning" in this embodiment includes processes of coating photoresist, mask exposure, development, etching, stripping photoresist, etc. when the material to be patterned is an inorganic material or a metal, and includes processes of mask exposure, development, etc. when the material to be patterned is an organic material, and evaporation, deposition, coating, etc. in this embodiment are well-established preparation processes in the related art.

S21: a base substrate 10 is provided. As will be understood by those skilled in the art, the substrate base plate 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 base plate 10, and the plurality of first electrodes 31 are arranged in an array. The first electrode 31 may be formed using techniques conventional in the art and will not be described in detail herein.

S23: the surface of the first electrode 31 is subjected to lyophobic treatment. CF may be used₄The solution performs lyophobic treatment on the surface of the first electrode 31, so that the surface of the first electrode 31 has lyophobic property.

S24: in a pixel region, an aqueous polymer solution is printed between the first electrodes corresponding to the red sub-pixel region and the green sub-pixel region, and after the aqueous polymer solution is cured, a sacrificial layer located between the two first electrodes is formed, as shown in fig. 13, where fig. 13 is a schematic view of a cross-sectional structure of F-F after the sacrificial layer is formed in the display 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 that 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 to form a first wall 51 and a second wall 52 between two adjacent columns and two adjacent rows, respectively, where 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, as shown in fig. 8 and 14, fig. 14 is a schematic view of a cross-sectional structure of F-F after the second wall is formed in the display substrate. The first retaining wall and the second retaining wall may be made of resin, silicon oxide, organic silicon or the like.

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 using a water dissolving method, and a channel 521 communicating the red sub-pixel region and the green sub-pixel region is formed. 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: the hole injection layers of the red and green sub-pixel regions are formed simultaneously. This step may include: printing hole injection ink 321 'in the red sub-pixel region or the green sub-pixel region by ink jet printing, wherein the hole injection ink 321' flows between the red sub-pixel region and the green sub-pixel region to fill the red sub-pixel region and the green sub-pixel region, as shown in fig. 15, fig. 15 is a schematic view of a cross-sectional structure of F-F of the display substrate after the hole injection ink is printed in the red sub-pixel region or the green sub-pixel region by ink jet printing; the hole injection ink is cured to simultaneously form the hole injection layers 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 of a cross-sectional structure of F-F after the hole injection layers are formed in the red sub-pixel region and the green sub-pixel region in the display substrate.

S28: and simultaneously forming the hole transport layers of the red sub-pixel region and the green sub-pixel region. This step may include: printing hole-transporting ink 322 'in the red sub-pixel region or the green sub-pixel region by ink-jet printing, wherein the hole-transporting ink 322' flows between the red sub-pixel region and the green sub-pixel region to fill the red sub-pixel region and the green sub-pixel region, as shown in fig. 17, fig. 17 is a schematic view of a cross-sectional structure of F-F after the hole-transporting ink is ink-jet printed in the red sub-pixel region or the green sub-pixel region in the display substrate; the hole transport ink is cured to simultaneously form the hole transport layer 322 of the red and green sub-pixel regions, as shown in fig. 12.

And finally, ink-jet printing is carried out on each sub-pixel region to form film layers such as an organic light-emitting layer and an electron injection layer, and a second electrode and a packaging structure layer are sequentially formed on one side of the light-emitting structure layer, which is far away from the substrate.

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 a 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", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

In the description of the embodiments of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Although the embodiments of the present invention have been described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A display substrate, comprising:

a substrate base plate;

2. The display substrate of claim 1,

3. The display substrate according to claim 2, wherein the first pixel partition has a height of 0.1 μm to 0.8 μm, and the second pixel partition has a height of 0.9 μm to 1.5 μm.

4. The display substrate according to claim 2 or 3, wherein the first pixel partition comprises a partition layer and a modification layer disposed on a surface of the partition layer facing away from the substrate, the modification layer changing from a lyophilic characteristic to a lyophobic characteristic when a temperature is greater than or equal to a critical temperature.

5. The display substrate of claim 4, wherein the modification layer is further located on both side wall surfaces of the partition layer.

6. The display substrate of claim 4, wherein the material of the modification layer comprises poly (N-isopropylacrylamide), and the critical temperature is 30 ℃ to 34 ℃.

7. The display substrate according to claim 1, wherein the pixel defining layer comprises a first dam defining a pixel region and a second dam disposed in the first dam and defining a sub-pixel region, a channel is disposed between at least one of the second dams and the substrate in the pixel region, the sub-pixel regions on both sides of the channel are communicated through the channel,

8. The display substrate according to claim 7, wherein 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 at both sides of the channel are communicated through the channel.

9. The display substrate according to claim 7, wherein the light emitting structure layer further comprises a hole transport layer disposed on a side of the hole injection layer away from the substrate, the height of the channel is greater than or equal to the thickness of the hole injection layer, the height of the channel is less than or equal to the sum of the thicknesses of the hole transport layer and the hole injection layer, and the hole injection layer and the hole transport layer in the sub-pixel regions on both sides of the channel are connected through the channel.

10. The display substrate according to any one of claims 7 to 9, wherein the pixel region comprises 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.

11. A method for preparing a display substrate is characterized by comprising the following steps:

12. The production method according to claim 11,

13. The production method according to claim 11,

14. A display device comprising the display substrate according to any one of claims 1 to 10.