Display substrate, display panel, and display device

Abstract

Provided are a display substrate, a display panel, and a display device. The display substrate comprises a base substrate, a pixel definition layer, a light-emitting functional layer, and a second electrode layer which are sequentially arranged; the light-emitting functional layer comprises a charge generation layer; the pixel definition layer defines pixel openings; the pixel definition layer comprises pixel definition portions, the sides of the pixel definition portions facing the pixel openings have undercut structures, each undercut structure comprises a first portion, a second portion and a third portion, the second portion retracts by a first distance with respect to the third portion in a direction moving away from the pixel openings, and the first portion protrudes by a second distance with respect to the third portion in a direction moving toward the pixel openings; the line connecting the edges of the first portion and the third portion respectively facing the pixel openings forms a first slope angle with a first direction, the second electrode layer comprises a second sub-portion of a second electrode located above the undercut structure, and the side edge of the second sub-portion of the second electrode facing the pixel openings has a second slope angle, and the first slope angle is smaller than the second slope angle.

Description

Display substrate, display panel, and display device Technical Field

[0001] The present disclosure relates to the field of display technology, and in particular to a display substrate, a display panel, and a display device. Background Art

[0002] Silicon-based organic light-emitting diodes (OLEDs) are micro-displays developed in recent years. Using mature silicon-based semiconductor process technology, OLED displays with high PPI (pixel density) and high refresh rate can be produced, which are used in the fields of VR (Virtual Reality) and AR (Augmented Reality). Silicon-based OLEDs use white light + three-color filtering to achieve color display, and use a charge generation layer (CGL) to connect multiple light-emitting layers in series to achieve the effect of light superposition. The display panel in the related art includes multiple pixel units to achieve a high PPI display effect. However, due to the precision limitations of the traditional fine metal mask (FMM), adjacent pixel units need to use a pixel isolation process to achieve isolation between pixels.

[0003] How to achieve effective isolation between pixels while minimizing leakage between pixels and ensuring the power consumption and lifespan of the display substrate is one of the important topics being studied by R&D personnel.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art.

[0005] Summary of the Invention

[0006] In one aspect, a display substrate is provided, wherein the display substrate includes: a base substrate; a pixel defining layer arranged on the base substrate; a light-emitting functional layer arranged on a side of the pixel defining layer away from the base substrate, wherein the light-emitting functional layer includes a charge generating layer; the pixel defining layer has a plurality of pixel openings, the plurality of pixel openings define a plurality of sub-pixels, and the plurality of sub-pixels are arrayed along a first direction and a second direction, the pixel defining layer includes a pixel defining portion located between two adjacent pixel openings, the pixel defining portion has an undercut structure on a side facing the pixel opening, wherein the undercut structure includes a first portion, a second portion, and a third portion, the first portion is located on a side of the second portion close to the base substrate, and the first portion protrudes a second distance relative to the third portion in a direction toward the pixel opening; the third portion is located On the side of the second part away from the base substrate, the second part is retracted by a first distance relative to the third part along the direction away from the pixel opening; the display substrate also includes a second electrode layer, and the second electrode layer is located on the side of the light-emitting functional layer away from the base substrate, wherein the second electrode layer includes a second electrode second sub-portion, and the positive projection of the second electrode second sub-portion on the base substrate at least partially overlaps with the positive projection of the undercut structure on the base substrate; and the second electrode layer extends continuously at the undercut structure, wherein a line connecting an edge of the first part facing the direction of the pixel opening and an edge of the third part facing the direction of the pixel opening forms a first slope angle with the first direction, and the side of the second sub-portion of the second electrode facing the direction of the pixel opening has a second slope angle, wherein the first slope angle is smaller than the second slope angle.

[0007] According to some exemplary embodiments, the first slope angle is less than 30°; and / or the second distance is greater than twice the first distance.

[0008] According to some exemplary embodiments, an edge of the first portion toward the pixel opening has a third slope angle, an edge of the third portion toward the pixel opening has a fourth slope angle, and the third slope angle is smaller than the fourth slope angle.

[0009] According to some exemplary embodiments, a side of the second sub-portion of the second electrode away from the pixel opening direction has a fifth slope angle, and the fifth slope angle is smaller than the first slope angle.

[0010] According to some exemplary embodiments, the pixel-defining layer includes: a first pixel-defining sublayer, a second pixel-defining sublayer, and a third pixel-defining sublayer stacked in sequence along a side away from the base substrate, wherein the first portion is located in the first pixel-defining sublayer, the second portion is located in the second pixel-defining sublayer, and the third portion is located in the third pixel-defining sublayer.

[0011] According to some exemplary embodiments, the display substrate further includes a first electrode layer, which is located on a side of the pixel defining layer close to the base substrate; the display substrate includes a plurality of first electrodes located in the first electrode layer, the plurality of first electrodes are arrayed in a first direction and a second direction, and the orthographic projections of the plurality of pixel openings on the base substrate respectively fall within the orthographic projections of the plurality of first electrodes on the base substrate; the pixel defining portion further includes a pixel defining main portion and an overlapping portion, the orthographic projection of the pixel defining main portion on the base substrate being located between the orthographic projections of two adjacent first electrodes on the base substrate, the orthographic projection of the overlapping portion on the base substrate overlaps with the orthographic projection of the first electrode on the base substrate, and the overlapping portion protrudes relative to the pixel defining main portion in a direction away from the base substrate.

[0012] According to some exemplary embodiments, the display substrate further includes a plurality of third electrodes, wherein the third electrodes are electrically connected to the first electrodes; the orthographic projection of the third electrodes on the base substrate at least partially overlaps with the orthographic projection of the pixel defining body portion on the base substrate; the third electrodes protrude relative to the first electrodes in a direction close to the base substrate; and the third electrodes protrude a third distance relative to the first electrode in a direction away from the pixel opening, wherein the third distance is greater than the second distance.

[0013] According to some exemplary embodiments, the side of the second portion facing the pixel opening direction has a sixth slope angle, the side of the overlapping portion away from the pixel opening direction has a seventh slope angle, and the side of the pixel-defining main portion facing the pixel opening direction has an eighth slope angle, wherein the sixth slope angle is greater than the seventh slope angle; and / or the seventh slope angle is greater than the first slope angle; and / or the first slope angle is greater than the eighth slope angle.

[0014] According to some exemplary embodiments, the first portion, the second portion and the third portion are all located on a side of the overlapping portion facing the pixel opening, and a surface of the second portion facing the pixel opening is a curved surface concave toward the pixel defining body portion.

[0015] According to some exemplary embodiments, the multiple sub-pixels include a first sub-pixel and a second sub-pixel adjacent to each other in a first direction or a second direction, the first sub-pixel includes a first pixel opening, and the second sub-pixel includes a second pixel opening; the pixel defining portion includes a pixel defining portion located between the first pixel opening and the second pixel opening, the pixel defining portion having an undercut structure on a first side toward the first pixel opening and a second side toward the second pixel opening, and the charge generating layer is disconnected at the undercut structure.

[0016] According to some exemplary embodiments, the display substrate includes a first charge generating sub-portion, a second charge generating sub-portion and a third charge generating sub-portion located in the charge generating layer, the orthographic projection of the first charge generating sub-portion on the substrate substrate at least partially overlaps with the orthographic projection of the first pixel opening on the substrate substrate, the orthographic projection of the second charge generating sub-portion on the substrate substrate at least partially overlaps with the orthographic projection of the second pixel opening on the substrate substrate, and the orthographic projection of the third charge generating sub-portion on the substrate substrate at least partially overlaps with the orthographic projection of the pixel defining portion on the substrate substrate, wherein the first charge generating sub-portion and the third charge generating sub-portion are disconnected at the undercut structure on the first side of the pixel defining portion, and the second charge generating sub-portion and the third charge generating sub-portion are disconnected at the undercut structure on the second side of the pixel defining portion.

[0017] According to some exemplary embodiments, the light-emitting functional layer includes a first light-emitting sublayer and a second light-emitting sublayer, the first light-emitting sublayer is located between the first electrode layer and the charge generation layer, and the second light-emitting sublayer is located on the side of the charge generation layer away from the substrate, wherein the first light-emitting sublayer is used to generate light of a first wavelength, and the second light-emitting sublayer is used to generate light of a second wavelength, wherein the light of the first wavelength includes yellow light or a mixed light of red and green; and / or the light of the second wavelength includes blue light.

[0018] According to some exemplary embodiments, the orthographic projections of any two of the second light-emitting sublayer, the first charge generating subportion, and the first portion of the undercut structure located on the first side of the pixel defining portion on the substrate at least partially overlap; and / or the orthographic projections of any two of the second light-emitting sublayer, the second charge generating subportion, and the first portion of the undercut structure located on the second side of the pixel defining portion on the substrate at least partially overlap.

[0019] According to some exemplary embodiments, the second pixel-defining sublayer has a second thickness in the third direction, the third pixel-defining sublayer has a third thickness in the third direction, and the maximum distance between the surface of the first charge generation sub-portion or the second charge generation sub-portion away from the substrate and the surface of the first electrode layer away from the substrate is a first height, wherein the third direction is perpendicular to both the first direction and the second direction, and the sum of the second thickness and the third thickness is greater than the first height.

[0020] According to some exemplary embodiments, the second distance is greater than the sum of the second thickness, the third thickness, and 0.5 times the first distance, wherein the sum of the second thickness, the third thickness, and 0.5 times the first distance is greater than 1100 angstroms.

[0021] According to some exemplary embodiments, the first distance is greater than or equal to 400 angstroms and less than or equal to 600 angstroms.

[0022] According to some exemplary embodiments, the second thickness is greater than or equal to 300 angstroms and less than or equal to 600 angstroms; and / or the third thickness is greater than or equal to 200 angstroms.

[0023] According to some exemplary embodiments, the first pixel defining sublayer has a first thickness in the third direction, and the first thickness is greater than or equal to 200 angstroms and less than or equal to 300 angstroms.

[0024] According to some exemplary embodiments, the third electrode has a fourth thickness in the third direction, and the first thickness is smaller than the fourth thickness.

[0025] According to some exemplary embodiments, a side of the overlapping portion away from the pixel opening has a fifth thickness, and the fifth thickness is less than the sum of the first thickness, the second thickness, and the third thickness.

[0026] According to some exemplary embodiments, the second distance is greater than 0.15 micrometers.

[0027] According to some exemplary embodiments, the third charge generating sub-section includes a first sub-section and a second sub-section, the orthographic projection of the first sub-section on the substrate substrate at least partially overlaps with the orthographic projection of the pixel defining main section on the substrate substrate, and the orthographic projection of the second sub-section on the substrate substrate at least partially overlaps with the orthographic projection of any one of the overlapping section and the third section on the substrate substrate; in the third direction, the maximum distance between the surface of the first sub-section away from the substrate substrate and the surface of the first electrode layer away from the substrate substrate is a second height, and the maximum distance between the surface of the second sub-section away from the substrate substrate and the surface of the first electrode layer away from the substrate substrate is a third height, and the third height is greater than the second height.

[0028] According to some exemplary embodiments, the second height is greater than the first height.

[0029] According to some exemplary embodiments, a height difference between the third height and the second height is greater than a height difference between the second height and the first height.

[0030] According to some exemplary embodiments, the second electrode layer further includes a first sub-portion of a second electrode and a third sub-portion of a second electrode, the orthographic projection of the first sub-portion of the second electrode on the substrate substrate at least partially overlaps with the orthographic projection of the first electrode on the substrate substrate; the orthographic projection of the second sub-portion of the second electrode on the substrate substrate at least partially overlaps with the orthographic projection of the overlapping portion on the substrate substrate; and the orthographic projection of the third sub-portion of the second electrode on the substrate substrate at least partially overlaps with the orthographic projection of the pixel-defining main portion on the substrate substrate; in the third direction, the maximum distance between the surface of the first sub-portion of the second electrode away from the substrate substrate and the surface of the first electrode layer away from the substrate substrate is a fourth height, the maximum distance between the surface of the second sub-portion of the second electrode away from the substrate substrate and the surface of the first electrode layer away from the substrate substrate is a fifth height, and the maximum distance between the surface of the third sub-portion of the second electrode away from the substrate substrate and the surface of the first electrode layer away from the substrate substrate is a sixth height, wherein the fifth height is greater than the sixth height, and the sixth height is greater than the fourth height.

[0031] According to some exemplary embodiments, a height difference between the fifth height and the sixth height is greater than a height difference between the sixth height and the fourth height.

[0032] According to some exemplary embodiments, the material of the first pixel defining sublayer includes SiO x ; and / or, the material of the second pixel definition sublayer includes SiN x; and / or, the material of the third pixel defining sublayer includes SiO x ; and / or, the material of the second electrode layer includes IZO.

[0033] In another aspect, a display panel is provided, comprising the display substrate as described in any one of the above items.

[0034] In yet another aspect, a display device is provided, comprising the display substrate as described in any one of the above items or the display panel as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above contents and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0036] FIG1 is a partial schematic plan view of a display substrate according to an embodiment of the present disclosure;

[0037] FIG2 is a schematic cross-sectional view of a display substrate according to an embodiment of the present disclosure, taken along line AA′ in FIG1 ;

[0038] FIG3A is a schematic cross-sectional view of a display substrate taken along line BB′ in FIG1 according to some embodiments of the present disclosure;

[0039] FIG3B is a schematic cross-sectional view of a display substrate taken along line BB′ in FIG1 according to other embodiments of the present disclosure;

[0040] 4 is a diagram showing a simulated relationship between a blue light spectrum of a display substrate and a first thickness of a first portion according to some embodiments of the present disclosure;

[0041] 5A and 5B are schematic diagrams showing evaporation effects of display substrates according to some embodiments of the present disclosure;

[0042] 6A and 6B are comparative diagrams showing distortion of display substrates according to some embodiments of the present disclosure;

[0043] FIG7 is a schematic cross-sectional view of a display substrate taken along line CC′ in FIG1 according to other embodiments of the present disclosure;

[0044] FIG8 is a schematic structural diagram of a display panel provided according to some embodiments of the present disclosure;

[0045] FIG9 is a schematic structural diagram of a display device according to some embodiments of the present disclosure.

[0046] It should be noted that, for the sake of clarity, in the drawings used to describe the embodiments of the present invention, the sizes of layers, structures or regions may be enlarged or reduced, that is, these drawings are not drawn according to the actual scale. DETAILED DESCRIPTION

[0047] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0048] It should be noted that in the drawings, the sizes and relative sizes of elements may be exaggerated for clarity and / or descriptive purposes. Thus, the sizes and relative sizes of the individual elements are not necessarily limited to those shown in the drawings. In the specification and drawings, the same or similar reference numerals indicate the same or similar parts.

[0049] Unless otherwise defined, technical or scientific terms used in this disclosure should have the ordinary meanings understood by those of ordinary skill in the art. The terms "first," "second," and similar terms used in this disclosure do not denote any order, quantity, or importance, but are simply used to distinguish different components. The terms "include," "comprising," and similar words mean that the element or object preceding the word encompasses the elements or objects listed after the word, and their equivalents, without excluding other elements or objects.

[0050] Unless otherwise specified, directional terms such as "upper," "lower," "left," "right," "inner," and "outer" are used herein to indicate positions or relationships based on the figures shown. These terms are intended solely to facilitate the description of the present disclosure and are not intended to indicate or imply that the devices, components, or parts referred to must have, be constructed, or operate in a specific orientation. It should be understood that when the absolute positions of the objects being described change, the relative positions they represent may also change accordingly. Therefore, these directional terms should not be construed as limiting the present disclosure.

[0051] It should be noted that, in this article, the term "the same layer" refers to a layer structure formed by using the same film-forming process to form a film layer used to form a specific pattern, and then patterning the film layer using the same mask through a single patterning process. Depending on the specific pattern, a single patterning process may include multiple exposure, development, or etching processes, and the specific pattern in the resulting layer structure may be continuous or discontinuous. In other words, multiple elements, components, structures, and / or parts located in the "same layer" are composed of the same material and are formed through the same patterning process. Typically, multiple elements, components, structures, and / or parts located in the "same layer" have approximately the same thickness.

[0052] Those skilled in the art should understand that, in this article, unless otherwise specified, the expression "height" or "thickness" refers to the dimension of the surface of each film layer arranged perpendicular to the display substrate, that is, the dimension along the light emitting direction of the display substrate, or the dimension along the normal direction of the display device.

[0053] In this document, the directional expressions "first direction" and "second direction" are used to describe different directions along a pixel unit, such as the longitudinal and transverse directions of a pixel unit, or the row and column directions of a sub-pixel arrangement. It should be understood that such expressions are merely exemplary descriptions and are not intended to limit the present disclosure.

[0054] The following briefly describes the technical terms involved in this disclosure so that relevant personnel can better understand this solution.

[0055] Transfer rate: The transfer rate is the ratio of the display substrate's luminous efficiency to the luminous efficiency of a reference light-emitting device fabricated using the same manufacturing process. The anode and cathode of the reference light-emitting device are continuous electrodes, and the reference light-emitting device is a single, integrated light-emitting unit. This eliminates the effects of leakage and other factors on the reference light-emitting device's luminous efficiency. The transfer rate can be used to measure leakage between pixel units in a display substrate; higher transfer rates indicate lower leakage between pixel units.

[0056] Distortion: Due to the large height difference at the partition structure, the evaporation material film layer in the OLED device may experience a rapid change in film morphology at the partition structure, resulting in distortion. The probability of leakage at the distorted location is higher.

[0057] Some exemplary embodiments of the present disclosure provide a display substrate, the display substrate comprising: a base substrate; a pixel defining layer disposed on the base substrate; a light-emitting functional layer disposed on a side of the pixel defining layer away from the base substrate, wherein the light-emitting functional layer comprises a charge generating layer; the pixel defining layer comprises a plurality of pixel openings, the plurality of pixel openings defining a plurality of sub-pixels, the plurality of sub-pixels being arrayed along a first direction and a second direction, the pixel defining layer comprising a pixel defining portion located between two adjacent pixel openings, the pixel defining portion having an undercut structure on a side facing the pixel openings, wherein the undercut structure comprises a first portion, a second portion, and a third portion, the first portion being located on a side of the second portion close to the base substrate, the first portion protruding relative to the third portion by a second distance in a direction facing the pixel openings. The display substrate further comprises a second electrode layer, the second electrode layer being located on a side of the light-emitting functional layer away from the substrate, the second electrode layer comprising a second sub-portion of the second electrode, the orthographic projection of the second sub-portion of the second electrode on the substrate at least partially overlapping the orthographic projection of the undercut structure on the substrate, and the second electrode layer extending continuously at the undercut structure, wherein a line connecting an edge of the first portion facing the pixel opening and an edge of the third portion facing the pixel opening forms a first slope angle with the first direction, and a side edge of the second sub-portion of the second electrode facing the pixel opening has a second slope angle, wherein the first slope angle is less than the second slope angle. By designing a pixel defining portion having multiple undercut structures between the pixel openings, the height of the pixel defining portion can be reduced while ensuring effective isolation between pixels, thereby making the topography of the electron transport layer and the cathode smooth, reducing leakage between pixels, improving the transfer rate of the light-emitting device, and improving the in-plane uniformity of the display substrate, thereby achieving better display effects.

[0058] FIG. 1 is a partial schematic plan view of a display substrate according to an embodiment of the present disclosure.

[0059] For example, in some embodiments of the present disclosure, referring to FIG. 1 , a display substrate 100 includes a display area AA and a plurality of subpixels SP located within the display area AA. The plurality of subpixels are arranged in an array along a first direction D1 and a second direction D2. The plurality of subpixels include a first subpixel SP1 and a second subpixel SP2 adjacent to each other in the first direction D1 or the second direction D2. The display substrate 100 also includes a pixel-defining layer PDL having a plurality of pixel openings 1. The plurality of pixel openings 1 define the plurality of subpixels SP. For example, the first subpixel SP1 includes a first pixel opening 11, and the second subpixel SP2 includes a second pixel opening 12. The pixel openings may be openings that include a light-emitting area.

[0060] It should be noted that the embodiments of the present disclosure do not impose any special restrictions on the design of the pixel opening 1. For example, although the pixel opening 1 is schematically shown as a square in the accompanying drawings, in other embodiments, the pixel opening can also be various shapes such as rectangular, elliptical, circular, triangular, etc. In addition, the light-emitting units of different colors corresponding to different pixel openings can adopt various arrangement methods known in the art, and the embodiments of the present disclosure do not impose any special restrictions.

[0061] FIG. 2 is a schematic cross-sectional view of a display substrate according to an embodiment of the present disclosure, taken along line AA′ in FIG. 1 .

[0062] For example, in some embodiments of the present disclosure, with reference to FIG1 and FIG2 , a display substrate 100 includes a base substrate 2 and a first electrode layer 3 disposed on the base substrate 2. The first electrode layer includes a plurality of first electrodes 31 arranged in an array in a first direction D1 and a second direction D2. The orthographic projections of the plurality of pixel openings 1 on the base substrate 2 fall within the orthographic projections of the plurality of first electrodes 31 on the base substrate 2. In other words, the plurality of first electrodes 31 correspond one-to-one to the positions of the plurality of sub-pixels SP, and the area of ​​the first electrodes is larger than the light-emitting area of ​​the sub-pixels.

[0063] For example, with continued reference to FIG. 2 , the pixel-defining layer (PDL) is located on a side of the first electrode layer 3 away from the base substrate. The pixel-defining layer (PDL) includes a pixel-defining portion PL1 located between the first pixel opening 11 and the second pixel opening 12. The pixel-defining portion PL1 has an undercut structure (UDC) on both a first side 111 facing the first pixel opening 11 and a second side 121 facing the second pixel opening 12. The display substrate further includes a light-emitting functional layer disposed on a side of the pixel-defining layer away from the base substrate 2. The light-emitting functional layer includes a charge generation layer 44. The charge generation layer 44 is disconnected at the undercut structure (UDC).

[0064] In stacked OLED devices, the high conductivity of the charge generation layer 44 can easily lead to lateral crosstalk between pixels when the charge generation layer is not isolated between adjacent pixels. By designing undercut structures at both ends of the pixel-defining portion, the charge generation layer between adjacent pixels can be disconnected at the undercuts, thereby reducing lateral crosstalk between pixels and improving the display quality of the display substrate.

[0065] For example, in some embodiments of the present disclosure, with continued reference to FIG. 2 , the undercut structure UDC includes a first portion UDC1, a second portion UDC2, and a third portion UDC3. The third portion UDC3 is located on a side of the second portion UDC2 away from the substrate 2. The second portion UDC2 is retracted from the third portion UDC3 by a first distance d1 away from the pixel opening. The first portion UDC1 protrudes from the third portion UDC3 toward the pixel opening by a second distance d2. For example, on the side of the pixel defining portion PL1 near the pixel opening 11, the second portion UDC2 is retracted from the third portion UDC3 by a first distance d1 away from the pixel opening 11. The first portion UDC1 protrudes from the third portion UDC3 toward the pixel opening 11 by a second distance d2. On the side of the pixel defining portion PL1 near the pixel opening 12, the second portion UDC2 is retracted from the third portion UDC3 by a first distance d1 away from the pixel opening 12. The first portion UDC1 protrudes from the third portion UDC3 toward the pixel opening 12 by a second distance d2. For example, in some embodiments of the present disclosure, the undercut structures on both sides of the pixel defining portion include a stacked structure of a first portion UDC1, a second portion UDC2, and a third portion UDC3, wherein the second portion UDC2 is recessed relative to the first portion UDC1 and the third portion UDC3. The undercut structures on both sides can be the same or different. For example, the second distance by which the first portion UDC1 of the UDC structure near the opening 11 protrudes relative to the third portion UDC3 toward the pixel opening can be the same or different from the second distance by which the first portion UDC1 of the UDC structure near the opening 12 protrudes relative to the third portion UDC3 toward the pixel opening. The recessed depths of the second portion UDC2 of the undercut structures UDC on both sides can also be the same or different.

[0066] By designing the undercut structures on both sides of the pixel defining portion into a structure with protruding ends and a concave middle, the required height of the pixel defining layer is relatively low while ensuring effective isolation of the charge generating layer. Therefore, the film layer located above the pixel defining layer can be made flatter at the edge of the undercut structure. For example, the cathode layer can be made flatter, thereby improving the uniformity of the electric field distribution within the pixel and reducing edge stray light.

[0067] For example, in some embodiments of the present disclosure, with continued reference to FIG. 2 , the pixel-defining layer (PDL) may include multiple pixel-defining sublayers, which may be stacked. For example, the pixel-defining layer (PDL) may include: a first pixel-defining sublayer (PDL1), a second pixel-defining sublayer (PDL2), and a third pixel-defining sublayer (PDL3), stacked sequentially along a side away from the base substrate 2. The first portion (UDC1) is located in the first pixel-defining sublayer (PDL1), the second portion (UDC2) is located in the second pixel-defining sublayer (PDL2), and the third portion (UDC3) is located in the third pixel-defining sublayer (PDL3).

[0068] The materials of the plurality of pixel definition sublayers may be the same or different. For example, the material of the first pixel definition sublayer PDL1 may include SiO x and / or, the material of the second pixel defining sublayer PDL2 may include SiN x and / or, the material of the third pixel defining sublayer PDL3 includes SiO x . Multiple pixel-defining sublayers can have different etching rates under the same etching process conditions. For example, the etching rate of the second pixel-defining sublayer can be higher than the etching rate of the third pixel-defining sublayer, so that an inward concave structure in which the second portion UDC2 is indented relative to the third portion UDC3 in a direction away from the pixel opening can be formed in the etching process, forming a pixel-defining portion with an undercut structure, which can effectively isolate the charge generation layer, reduce lateral crosstalk between pixels, reduce leakage rate, improve the transfer rate of the display substrate, and improve the display effect of the display substrate.

[0069] For example, continuing to refer to Figure 2, the pixel-defining portion PL1 also includes a pixel-defining main portion PL11 and an overlapping portion PL12. The orthographic projection of the pixel-defining main portion PL11 on the base substrate 2 is located between the orthographic projections of the two adjacent first electrodes 31 on the base substrate 2. The orthographic projection of the overlapping portion PL12 on the base substrate 2 overlaps with the orthographic projection of the first electrode 31 on the base substrate 2. The overlapping portion PL12 protrudes relative to the pixel-defining main portion PL11 in a direction away from the base substrate 2.

[0070] For example, in some embodiments of the present disclosure, the first portion UDC1, the second portion UDC2, and the third portion UDC3 are all located on the side of the overlap portion PL12 facing the pixel opening. The surface of the second portion UDC2 facing the pixel opening 1 is a curved surface concave toward the pixel defining body portion PL11.

[0071] Because the overlapping portion PL12 has a significant height difference from the first electrode 31 in the third direction D3, and the overlapping portion PL12 includes a concave curved surface in the middle, the charge generation layer 44 is susceptible to film fracture in the area near the overlapping portion PL12. This disconnects the charge generation layer and reduces lateral crosstalk between pixels. The third direction D3 is perpendicular to both the first direction D1 and the second direction D2.

[0072] For example, in some embodiments of the present disclosure, with continued reference to FIG. 2 , the display substrate 100 includes a first charge generation sub-section 441, a second charge generation sub-section 442, and a third charge generation sub-section 443 located in the charge generation layer 44. The orthographic projection of the first charge generation sub-section 441 on the substrate at least partially overlaps with the orthographic projection of the first pixel opening 11 on the substrate, the orthographic projection of the second charge generation sub-section 442 on the substrate at least partially overlaps with the orthographic projection of the second pixel opening 12 on the substrate, and the orthographic projection of the third charge generation sub-section 443 on the substrate at least partially overlaps with the orthographic projection of the pixel defining portion PL1 on the substrate. In other words, the charge generation layer between two adjacent pixels can be divided into three distinct sub-sections due to the interruption of the pixel defining portion. The first charge generation sub-section 441 and the third charge generation sub-section 443 are disconnected at an undercut structure on the first side 111 of the pixel defining portion, while the second charge generation sub-section 442 and the third charge generation sub-section 443 are disconnected at an undercut structure on the second side 121 of the pixel defining portion.

[0073] By designing undercut structures on both sides of the pixel defining portion, it can be ensured that the charge generation layers above the pixel opening areas on both sides of the pixel defining portion are effectively disconnected from the charge generation layer above the pixel defining portion, thereby avoiding lateral leakage between some pixel units and the charge generation layer above the pixel defining portion, which would result in uneven luminescence of the display substrate.

[0074] For example, in some embodiments of the present disclosure, the display substrate may include a silicon-based OLED display substrate. Among them, the silicon-based OLED can realize the colorization of the display by using white light + three-color filtering. White light OLED can generally include a plurality of light-emitting layers with a stacked design, and different light-emitting layers can produce light of different colors. White light is formed by mixing light of different colors, and further, the mixed white light is combined with the filter structure to achieve the effect of color display. For example, different light-emitting layers may include a yellow light-emitting layer and a blue light-emitting layer, or a red and green mixed light-emitting layer and a blue light-emitting layer. White light can be achieved by mixing yellow light with blue light, or mixing red and green mixed light with blue light. However, since the lighting voltages of the light-emitting layers of different colors in the stacked device are different, the luminous efficiency is also different. Under different external electric fields, the color of the mixed light is prone to color deviation as the voltage changes, thereby reducing the display effect. For example, the lighting voltage of blue light is higher than that of yellow light or red and green light. When displaying at low grayscale, due to the low voltage of the external electric field, the blue light emitting layer may not be lit or the lighting brightness may be insufficient, resulting in a yellowish display at low grayscale.

[0075] The inventors have found that the pixel defining portion can be used to adjust the luminous areas of different luminous layers to a certain extent, for example, adjusting the area of ​​the blue light emitting layer to be slightly larger than the luminous area of ​​the yellow light emitting layer, thereby adjusting the display effect of the display substrate.

[0076] FIG. 3A is a schematic cross-sectional view of a display substrate taken along line BB′ in FIG. 1 according to some embodiments of the present disclosure.

[0077] For example, in some embodiments of the present disclosure, referring to FIG3A , the display substrate further comprises a second electrode layer 5 . The second electrode layer 5 is located on a side of the light-emitting functional layer 4 away from the base substrate. The second electrode layer comprises a first second electrode sub-portion 51, a second second electrode sub-portion 52, and a third second electrode sub-portion 53. The orthographic projection of the first second electrode sub-portion 51 on the base substrate at least partially overlaps with the orthographic projection of the pixel opening on the base substrate; the orthographic projection of the second second electrode sub-portion 52 on the base substrate at least partially overlaps with the orthographic projection of the undercut structure UDC on the base substrate; the orthographic projection of the third second electrode sub-portion 53 on the base substrate at least partially overlaps with the orthographic projection of the pixel defining body on the base substrate; and the second electrode layer 5 extends continuously at the undercut structure. For example, the first second electrode sub-portion 51 is located in the light-emitting area of ​​the display substrate, the third second electrode sub-portion 53 is located in the non-light-emitting area of ​​the display substrate, and the second second electrode sub-portion 52 is located at the intersection of the non-light-emitting and light-emitting areas of the display substrate. Because the pixel defining portion is provided at the edge of the light-emitting area of ​​the pixel unit, the film layer of the second second electrode sub-portion 52 in this area becomes uneven.

[0078] Exemplarily, a line connecting an edge of the first portion UDC1 toward the pixel opening 1 and an edge of the third portion UDC3 toward the pixel opening 1 forms a first slope angle α1 with the first direction D1, and a side of the second sub-portion 52 of the second electrode toward the pixel opening 1 has a second slope angle α2, wherein the first slope angle α1 is smaller than the second slope angle α2.

[0079] Exemplarily, in some embodiments of the present disclosure, referring to FIG. 3A , the first slope angle α1 is less than 30°.

[0080] For example, in some embodiments of the present disclosure, referring to FIG. 3A , a side of the second electrode second sub-portion 52 away from the pixel opening 1 has a fifth slope angle α5 , and the fifth slope angle α5 is smaller than the first slope angle α1 .

[0081] Exemplarily, in some embodiments of the present disclosure, referring to FIG. 2 , the second distance d2 is greater than twice the first distance d1 .

[0082] By designing the undercut structure (UDC) and ensuring that the first slope angle of the undercut structure is smaller than the second slope angle of the second electrode layer, the charge generation layer is isolated at the UDC while the second electrode layer is not broken at the UDC, thereby improving the in-plane uniformity of the display substrate. By ensuring that the fifth slope angle is smaller than the first slope angle, the second electrode layer located on the side of the overlap away from the pixel opening is more gently sloping, which helps improve the uniformity of the electric field distribution and the in-plane uniformity of the display substrate.

[0083] For example, in some embodiments of the present disclosure, continuing to refer to Figure 3A, the edge of the layer where the first part UDC1 is located in the direction toward the pixel opening 1 has a third slope angle α3, and the edge of the layer where the third part UDC3 is located in the direction toward the pixel opening 1 has a fourth slope angle α4, and the third slope angle α3 is smaller than the fourth slope angle α4.

[0084] Exemplarily, in some embodiments of the present disclosure, in combination with Figures 2 and 3A, the side of the second part UDC2 toward the pixel opening 1 has a sixth slope angle α6, the side of the overlapping portion PL12 away from the pixel opening 1 has a seventh slope angle α7, and the side of the pixel-defining main portion PL11 toward the pixel opening 1 has an eighth slope angle α8, wherein the sixth slope angle α6 is greater than the seventh slope angle α7; and / or the seventh slope angle α7 is greater than the first slope angle α1; and / or the first slope angle α1 is greater than the eighth slope angle α8.

[0085] By optimizing the edge inclination angles of the pixel defining main portion and the overlapping portion in the pixel defining portion, the film layer of the second electrode layer at the undercut structure can be made smoother, ensuring that the second electrode layer is not broken at the undercut structure, thereby improving the in-plane uniformity of the display substrate.

[0086] For example, in some embodiments of the present disclosure, a sub-pixel may include an OLED stacked device, which is configured to generate white light under electric field control. Referring to FIG3 , the light-emitting functional layer 4 in the OLED stacked device may include a first light-emitting sublayer 42 and a second light-emitting sublayer 46. The first light-emitting sublayer 42 is located between the first electrode layer 3 and the charge generation layer 44, and the second light-emitting sublayer 46 is located on the side of the charge generation layer 44 away from the substrate 2. The first light-emitting sublayer 42 is configured to generate light of a first wavelength, and the second light-emitting sublayer 46 is configured to generate light of a second wavelength. For example, the first wavelength of light may include yellow light or a mixture of red and green light; the second wavelength of light may include blue light.

[0087] In some embodiments, the first luminescent sublayer may include a single film layer formed by the mixed vaporization of a main material and a yellow luminescent dye; or, the first luminescent sublayer may include a single film layer formed by the mixed vaporization of multiple materials including a main material, a green luminescent dye, and a red luminescent dye; or, the first luminescent sublayer may include multiple luminescent film layers. For example, the first luminescent sublayer may include a film layer formed by the mixed vaporization of a main material one and a green luminescent material, and a film layer formed by the mixed vaporization of a main material two and a red luminescent material. The main material one and the main material two may be the same or different.

[0088] Exemplarily, the light-emitting functional layer 4 may further include a first hole functional layer 41, a first electron functional layer 43, a second hole functional layer 45, and a second electron functional layer 47. For example, the first hole functional layer 41 and the second hole functional layer 45 may include multiple film layers such as a hole injection layer, a hole transport layer, and an electron blocking layer, and the first electron functional layer 43 and the second electron functional layer 47 may include multiple film layers such as an electron injection layer, an electron transport layer, and a hole blocking layer.

[0089] For example, the orthographic projections of any two of the second light-emitting sublayer 46, the first charge generating sub-section 441, and the first portion UDC1 of the undercut structure located on the first side 111 of the pixel defining portion on the substrate at least partially overlap. Because the first portion UDC1 is an insulating layer, the portion 421 of the first light-emitting sublayer 42 located within the dotted box region S cannot emit light due to the isolation of the insulating layer. However, the portion 461 of the second light-emitting sublayer 46 located within region S can emit light, for example, blue light, because both the first charge generating sub-section 441 and the second electrode layer 5 are conductive. Due to the protruding design of the first portion UDC1, the light-emitting area of ​​the second light-emitting sublayer within the same sub-pixel is slightly larger than that of the first light-emitting sublayer, partially compensating for the insufficient brightness of the second light-emitting sublayer at low voltages. For example, when the second light-emitting sublayer emits blue light, the blue light emission efficiency at low voltages can be relatively improved, thereby enhancing the display quality of the display substrate at low grayscales.

[0090] Similarly, referring to FIG2 and FIG3A , the orthographic projections of any two of the second light-emitting sublayer 46, the second charge generation sub-section 442, and the first portion UDC1 of the undercut structure located on the second side 121 of the pixel-defining portion on the substrate also at least partially overlap. By designing the first portion UDC1 of the pixel-defining portion between multiple pixel units to protrude relative to the second portion UDC2, the light-emitting area of ​​the second light-emitting sublayer located above the charge generation layer in the same pixel unit can be slightly larger than the light-emitting area of ​​the first light-emitting sublayer located below the charge generation layer. This allows for adjusting the light color of the OLED light-emitting device at low grayscale levels, improving the display quality of the display substrate.

[0091] For example, in some embodiments of the present disclosure, continuing to refer to Figure 3A, the second pixel defining sublayer PDL2 has a second thickness h2 in the third direction D3, the third pixel defining sublayer PDL3 has a third thickness h3 in the third direction D3, and the maximum distance between the surface of the first charge generating sub-portion 441 away from the substrate and the surface of the first electrode layer 3 away from the substrate is a first height H1, wherein the third direction D3 is perpendicular to both the first direction D1 and the second direction D2, and the sum of the second thickness h2 and the third thickness h3 is greater than the first height H1.

[0092] By designing a portion of the charge generation layer located in the pixel opening area to be at a height less than the sum of the thicknesses of the two upper pixel-defining sublayers in the pixel-defining layer from the first electrode layer, it is possible to ensure that there is a height difference between the charge generation layer located in the pixel opening area and the charge generation layer located above the pixel-defining layer. This can better achieve the isolation of the charge generation layer at the bottom cut structure of the pixel-defining layer, thereby reducing lateral crosstalk between pixels and reducing leakage in the display substrate, which is beneficial to improving the transfer rate of the display substrate and improving the display effect of the display substrate.

[0093] For example, in some embodiments of the present disclosure, referring to FIG. 2 and FIG. 3A , the second distance d2 is greater than the sum of the second thickness h2 , the third thickness h3 , and 0.5 times the first distance d1 , ie, d2 > h2 + h3 + 0.5*d1 .

[0094] For example, the sum of the second thickness h2, the third thickness h3, and 0.5 times the first distance d1 is greater than 1100 angstroms. The concave design of the second portion UDC2 increases the effective isolation distance of the undercut structure, reducing the physical thickness of the undercut structure while ensuring that the undercut structure effectively isolates the charge generation layer. When the physical thickness of the undercut structure is reduced, the second electrode layer located above the undercut structure can become flatter, ensuring that the second electrode layer remains continuous at the undercut structure, which helps improve the in-plane uniformity of the display substrate.

[0095] In some embodiments, the larger the second thickness h2 of the second pixel defining sublayer PDL2, the better the isolation effect of the charge generation layer between pixels. However, the thickness selection of the second thickness h2 also needs to take into account the impact on the spectrum of the stacked device. When the second thickness is larger, the distance between the first charge generating subsection 441 and the third charge generating subsection 443 is greater, and the function of the first charge generating subsection 441 in the distortion area (the area formed by the abrupt change of the film layer near a part of the undercut structure) is reduced. For example, it may cause the luminous effect of the second light-emitting sublayer 461 within the range of area S to be weakened, and the OLED device tends to light up first with the intrinsic yellow light or green light, thereby causing the low grayscale of the display substrate to be yellowish.

[0096] For example, the second thickness h2 is greater than or equal to 300 angstroms and less than or equal to 600 angstroms; and / or the third thickness h3 is greater than or equal to 200 angstroms. By optimizing the second thickness h2 of the second pixel-defining sublayer (PDL2), it is possible to maintain the effect of regulating the low-grayscale spectrum of the display substrate while ensuring effective isolation of the charge generation layer. This can reduce leakage rate and improve the transfer rate of the display substrate, which is conducive to improving the efficiency and lifespan of the display substrate. It can also regulate the spectrum of the display substrate and enhance the display effect of the display substrate.

[0097] For example, in some embodiments of the present disclosure, referring to FIG2 , the second portion UDC2 located in the second pixel-defining sublayer is retracted by a first distance d1 relative to the third portion UDC3 located in the third pixel-defining sublayer in a direction away from the pixel opening, thereby forming a pixel-defining portion having an undercut structure. The depth of the undercut structure will affect the isolation effect of the pixel-defining portion. Generally speaking, the greater the depth of the undercut structure, that is, the greater the first distance d1, the better the isolation effect. However, the design of the first distance also needs to take into account the influence of parameters such as the stability of the undercut structure itself and the etching rate of the materials of both the second pixel-defining sublayer and the third pixel-defining sublayer.

[0098] For example, the undercut structure can be formed by a simultaneous etching process of the second pixel definition sublayer PDL2 and the third pixel definition sublayer PDL3. Due to limitations such as etching rate and film support structure, the depth of the undercut structure will be affected by the material properties and film thickness of the second pixel definition sublayer PDL2 and the third pixel definition sublayer PDL3. For example, when the material of the second pixel definition sublayer PDL2 is SiN x The material of the third pixel definition sublayer PDL3 is SiO x When, preferably, the first distance d1 is greater than or equal to 400 angstroms and less than or equal to 600 angstroms. By optimizing the depth of the undercut structure, on the one hand, the structural stability of the undercut structure itself can be ensured, and on the other hand, the isolation effect of the pixel defining layer can be improved as much as possible, leakage can be reduced, and the transfer rate of the display substrate can be improved. Due to the use of an undercut structure with protruding ends and a concave middle, when the pixel defining portion isolates the charge generation layer, a certain distance of the concave second pixel defining sublayer is increased, so that the required height of the pixel defining layer is smaller, thereby making the second electrode layer located above the pixel defining layer flatter, and the electric field distribution above the second electrode layer will be more uniform, which is beneficial to improving the in-plane uniformity of the display substrate.

[0099] FIG. 3B is a schematic cross-sectional view of a display substrate taken along line BB′ in FIG. 1 according to some other embodiments of the present disclosure.

[0100] For example, in some embodiments of the present disclosure, referring to FIG. 3B , the display substrate further includes a plurality of third electrodes 8, wherein the third electrodes 8 are electrically connected to the first electrodes 31. For example, the first electrode 31 may include a plurality of electrode sublayers arranged in a stacked manner, such as a first electrode first sublayer 311, a first electrode second sublayer 312, and a first electrode third sublayer 313, and the third electrode 8 may be located on the same layer as the first electrode third sublayer 313. For example, the material of the first electrode first sublayer 311 may include titanium, the material of the first electrode second sublayer 312 may include silver, the material of the first electrode third sublayer 313 may include ITO, and the material of the third electrode 8 may include ITO.

[0101] Exemplarily, in combination with FIG2 and FIG3B , the orthographic projection of the third electrode 8 on the base substrate at least partially overlaps with the orthographic projection of the pixel defining main portion PL11 on the base substrate; the third electrode 8 protrudes relative to the first electrode 31 in a direction close to the base substrate; and the third electrode 8 protrudes relative to the first electrode 31 in a direction away from the pixel opening 1 by a third distance d3, wherein the third distance d3 is greater than the second distance d2.

[0102] By arranging a third electrode at the edge of the gap between adjacent pixel openings and electrically connecting the third electrode to the first electrode, the edge electric field of the pixel unit can be balanced, the edge stray light of the pixel unit can be reduced, the uniformity of the display unit can be improved, and the display effect of the display substrate can be enhanced.

[0103] For example, in some embodiments of the present disclosure, with continued reference to FIG. 3B , the third electrode 8 has a fourth thickness h4 in the third direction D3, and the first portion UDC1 has a first thickness h1 in the third direction, where the first thickness h1 is less than the fourth thickness h4. The layer where the first portion UDC1 is located is closer to the light-emitting region. By adjusting the first thickness h1 of the first portion UDC1 and the fourth thickness h4 of the third electrode 8, the electric field transition from the light-emitting region to the non-light-emitting region can be smoother, thereby improving the uniformity of the pixel unit.

[0104] For example, in some embodiments of the present disclosure, with continued reference to FIG. 3B , the side of the overlapping portion PL12 facing away from the pixel opening 1 has a fifth thickness h5, which is less than the sum of the first thickness h1, the second thickness h2, and the third thickness h3. By designing the side of the overlapping portion of the pixel defining portion facing away from the pixel opening to have a gradually descending structure, the second electrode layer located on the side of the overlapping portion facing away from the pixel opening can be made smoother, ensuring that the second electrode layer located at the intersection of the overlapping portion and the pixel defining body remains continuous, thereby improving the in-plane uniformity of the display substrate.

[0105] For example, in some embodiments of the present disclosure, referring to FIG3B , the display substrate may include a second electrode layer 5, the second electrode layer 5 being located on a side of the light-emitting functional layer 4 away from the base substrate, the second electrode layer including a second electrode first sub-portion 51, a second electrode second sub-portion 52, and a second electrode third sub-portion 53, the orthographic projection of the second electrode first sub-portion 51 on the base substrate at least partially overlaps with the orthographic projection of the pixel opening on the base substrate; the orthographic projection of the second electrode second sub-portion 52 on the base substrate at least partially overlaps with the orthographic projection of the undercut structure UDC on the base substrate; the orthographic projection of the second electrode third sub-portion 53 on the base substrate at least partially overlaps with the orthographic projection of the pixel defining body portion PL11 on the base substrate; and the second electrode layer 5 extends continuously at the undercut structure, wherein a line connecting an edge of the first portion UDC1 toward the pixel opening 1 and an edge of the third portion UDC3 toward the pixel opening 1 forms a first slope angle α1 with the first direction D1, and a side of the second electrode second sub-portion 52 toward the pixel opening 1 has a second slope angle α2, wherein the first slope angle α1 is smaller than the second slope angle α2.

[0106] By designing the undercut structure UDC, it can be ensured that the charge generation layer is isolated at the undercut structure while the second electrode layer is not broken at the undercut structure UDC, thereby improving the in-plane uniformity of the display substrate.

[0107] FIG. 4 is a diagram illustrating a simulated relationship between a blue light spectrum of a display substrate and a first thickness of a first portion according to some embodiments of the present disclosure.

[0108] For example, in some embodiments of the present disclosure, referring to FIG2 and FIG3A , a first portion UDC1 of the first pixel-defining sublayer protrudes toward the pixel opening relative to a third portion UDC3 of the third pixel-defining sublayer by a second distance d2. This can increase the luminous area of ​​the second light-emitting sublayer 46 at low grayscales to a certain extent, thereby adjusting the spectrum of the display substrate at low grayscales and preventing a yellowish cast in low grayscale images. Therefore, the display effect of the display substrate can be controlled by adjusting the second distance d2 by which the first portion of the first pixel-defining sublayer protrudes toward the pixel opening relative to the third portion of the third pixel-defining sublayer.

[0109] The first pixel-defining sublayer has a first thickness h1 in the third direction. This first thickness h1 affects the isolation effect of the inscribed structure of the pixel-defining portion. For example, when the depth of the inscribed structure is constant, increasing the first thickness h1 of the first pixel-defining sublayer increases the distortion inside the third portion UDC3, thereby reducing the low-resistance effect of the second light-emitting sublayer 46 and causing the light emitted by the second light-emitting sublayer to weaken. For example, FIG4 shows a blue light spectrum diagram of multiple display substrates with different first portion thicknesses based on simulation. Referring to FIG4 , the abscissa represents the blue light spectrum of the display substrate, the ordinate represents the blue light luminescence intensity, and the footing refers to the first portion UDC1 of the pixel-defining layer located in the first pixel-defining sublayer. When the first thickness h1 of the first portion UDC1 is increased, the impurity peak of blue light around 480nm increases, and the brightness of the blue light decreases, thereby affecting the display effect of the display substrate.

[0110] The inventors have found that, in an actual display substrate, when the first thickness of the first portion increases, the simulation results are consistent with the above. As the first thickness of the first portion increases, the impurity peaks of blue light around 480nm increase, and the brightness of the blue light decreases.

[0111] Therefore, the luminous effect of the second luminous sublayer can be adjusted by adjusting the first thickness h1 of the first pixel defining sublayer, thereby affecting the overall display effect of the display substrate.

[0112] Exemplarily, the second distance d2 is greater than 0.15 micrometers.

[0113] Exemplarily, the first thickness h1 of the first pixel defining sublayer is greater than or equal to 200 angstroms and less than or equal to 300 angstroms.

[0114] By optimizing the first thickness of the first pixel-defining sublayer and the second distance of the protrusion of the first portion UDC1 in the first pixel-defining sublayer, the pixel-defining portion can effectively isolate the charge generation layer to avoid leakage, and can also adjust the light-emitting area and light-emitting brightness of the second light-emitting layer relative to the first light-emitting layer, thereby improving the yellowish phenomenon of low-grayscale display of the display substrate and enhancing the display effect of the display substrate.

[0115] 5A and 5B are schematic diagrams showing the evaporation effect of a display substrate according to some embodiments of the present disclosure.

[0116] For example, in some embodiments of the present disclosure, during the production of an OLED display substrate, a point evaporation source is typically used as the evaporation source. Due to the obstruction of the pixel defining layer and the mask, during the evaporation process, the pixel unit has a negative side and a positive side relative to the point evaporation source. The positive side is less obscured, while the negative side is more obscured. Therefore, in the same evaporation process, the thickness of the film formed on the positive side and the negative side is different, resulting in different widths of the distortion zone. For example, referring to Figure 5A, the left side is the negative side S1 and the right side is the positive side S2. After the pixel defining portion is formed, the display substrate is usually further deposited on the substrate using methods such as evaporation or sputtering, such as multiple organic and inorganic film layers, such as an electron transport layer, a light-emitting functional layer, a charge generation layer, a hole transport layer, and a cathode material layer. Among them, a portion of the film layers can be disconnected at the undercut structure of the pixel defining portion, such as the charge generation layer, and a portion of the film layers can extend continuously at the undercut structure of the pixel defining portion, such as the cathode film layer. Due to the obstruction of the pixel defining portion, the film morphology and thickness of the multiple film layers deposited on both sides of the pixel defining portion will be different. For example, referring to Figure 5B, when evaporating the light-emitting functional layer, three organic sources VS, including a dual host H and a single doped dye D, can be co-evaporated to form the light-emitting functional layer. Due to the obstruction of the pixel defining part PDL, the film layer structure formed on the negative side is different from the film layer structure formed on the positive side.

[0117] It should be noted that the dual host H and single doped dye D in the light-emitting functional layer disclosed in the present invention are only for illustrative purposes and do not limit the structure of the light-emitting functional layer disclosed in the present invention. The light-emitting functional layer disclosed in the present invention can adopt various doping structures known in the art, and the embodiments of the present invention are not particularly limited.

[0118] For example, in some embodiments of the present disclosure, the distortion width inside the pixel-defining portion on the negative side is greater than the distortion width inside the pixel-defining portion on the positive side.

[0119] 6A and 6B are comparative diagrams of distortion of display substrates according to some embodiments of the present disclosure.

[0120] For example, in some embodiments of the present disclosure, due to obstruction by the pixel defining portion, the distortion of various film layers in the light-emitting device on the sun-facing and sun-facing sides varies. The degree of distortion can be measured by the ratio of the distortion width inside the pixel defining portion to the height of the charge generation layer inside the pixel defining portion. A larger ratio indicates more severe distortion and poorer display uniformity of the display substrate. Referring to Figures 6A and 6B, when the pixel defining portion also employs an undercut structure, the second distance d21 by which the first portion UDC1 protrudes from the first pixel defining sublayer in Figure 6A is smaller than the second distance d22 by which the first portion UDC1 protrudes from the first pixel defining sublayer in Figure 6B. By comparing the display substrates in Figures 6A and 6B, the effect of the second distance on the uniformity of the display substrate can be compared.

[0121] In some embodiments, the distortion width on the left side (negative side) of the display substrate in FIG6A is 60 nm, the distortion width on the right side (positive side) is 50 nm, and the height of the charge generation layer inside the pixel defining portion is 33 nm. The ratio of the distortion width on the left side of FIG6A to the height of the charge generation layer is 1.82, and the ratio of the distortion width on the right side of FIG6A to the height of the charge generation layer is 1.52. The distortion width on the left side (negative side) of the display substrate in FIG6B is 90 nm, the distortion width on the right side (positive side) is 70 nm, and the height of the charge generation layer inside the pixel defining portion is 50 nm. The ratio of the distortion width on the left side of FIG6B to the height of the charge generation layer is 1.8, and the ratio of the distortion width on the right side of FIG6B to the height of the charge generation layer is 1.4. By comparing the display substrates of FIG6A and FIG6B, it can be found that appropriately increasing the second distance can reduce the degree of distortion and improve the uniformity of the display substrate. For example, the second distance d2 is greater than 0.15 micrometers, which can improve the distortion of each film layer of the pixel unit, enhance the consistency of the positive and negative surfaces of the point source evaporation, and help improve the in-plane uniformity of the display substrate.

[0122] FIG. 7 is a schematic cross-sectional view of a display substrate taken along line CC′ in FIG. 1 according to some other embodiments of the present disclosure.

[0123] Exemplarily, in some embodiments of the present disclosure, referring to Figure 7, the third charge generating sub-section 443 includes a first sub-section 4431 and a second sub-section 4432, the orthographic projection of the first sub-section 4431 on the substrate substrate at least partially overlaps with the orthographic projection of the pixel defining main section PL11 on the substrate substrate, and the orthographic projection of the second sub-section 4432 on the substrate substrate at least partially overlaps with the orthographic projection of any one of the overlapping section PL12 and the third section UDC3 on the substrate substrate.

[0124] In the third direction D3, the maximum distance between the surface of the first sub-portion 4431 away from the substrate and the surface of the first electrode layer 3 away from the substrate is a second height H2, and the maximum distance between the surface of the second sub-portion 4432 away from the substrate and the surface of the first electrode layer 3 away from the substrate is a third height H3, and the third height H3 is greater than the second height H2.

[0125] Exemplarily, the maximum distance between the surface of the second charge generating sub-unit 442 away from the substrate and the surface of the first electrode layer 3 away from the substrate is a first height H1, and the second height H2 is greater than the first height H1.

[0126] Exemplarily, a height difference between the third height H3 and the second height H2 is greater than a height difference between the second height H2 and the first height H1 .

[0127] By designing the undercut structure on both sides of the pixel defining portion, the charge generation layers located in different areas can have different heights, thereby forming a film break, thereby achieving the purpose of horizontal isolation between pixels, which is beneficial to reducing leakage, improving the transfer rate of the display substrate, and enhancing the display effect of the display substrate.

[0128] For example, in some embodiments of the present disclosure, referring to FIG7 , the display substrate includes a second electrode layer 5 . For example, the second electrode layer may be a cathode layer on the entire surface. The material of the second electrode layer may include a transparent electrode film, such as an IZO film.

[0129] Exemplarily, continuing to refer to Figure 7, the second electrode layer 5 may include a second electrode first sub-portion 51, a second electrode second sub-portion 52, and a second electrode third sub-portion 53, wherein the orthographic projection of the second electrode first sub-portion 51 on the substrate substrate at least partially overlaps with the orthographic projection of the first electrode 31 on the substrate substrate; the orthographic projection of the second electrode second sub-portion 52 on the substrate substrate at least partially overlaps with the orthographic projection of the overlapping portion PL12 on the substrate substrate; and the orthographic projection of the second electrode third sub-portion 53 on the substrate substrate at least partially overlaps with the orthographic projection of the pixel-defining main portion PL11 on the substrate substrate.

[0130] In the third direction, the maximum distance between the surface of the first sub-portion 51 of the second electrode away from the substrate and the surface of the first electrode layer 3 away from the substrate is a fourth height H4, the maximum distance between the surface of the second sub-portion 52 of the second electrode away from the substrate and the surface of the first electrode layer 3 away from the substrate is a fifth height H5, and the maximum distance between the surface of the third sub-portion 53 of the second electrode away from the substrate and the surface of the first electrode layer 3 away from the substrate is a sixth height H6, wherein the fifth height H5 is greater than the sixth height H6, and the sixth height H6 is greater than the fourth height H4.

[0131] A height difference between the fifth height H5 and the sixth height H6 is greater than a height difference between the sixth height H6 and the fourth height H4 .

[0132] The second electrode layer exhibits significant film variations at the edge of the pixel defining layer. The thicker the pixel defining layer, the more dramatic the film variations at the edge of the second electrode layer, making them more susceptible to distortion, leading to leakage or uneven electric field distribution, impacting display quality. A pixel defining portion with an undercut structure, with protruding ends and a concave center, achieves the same charge generation layer isolation effect while maintaining a smaller thickness. This effectively mitigates film variations in the second electrode layer, improving the uniformity of the electric field distribution within the second electrode layer, thereby enhancing the in-plane uniformity of the display substrate and enhancing display quality.

[0133] FIG8 is a schematic structural diagram of a display panel according to some embodiments of the present disclosure.

[0134] Optionally, an embodiment of the present disclosure provides a display panel. Referring to FIG. 8 , the display panel 200 may include the display substrate 100 described above.

[0135] FIG9 is a schematic structural diagram of a display device according to some embodiments of the present disclosure.

[0136] Optionally, embodiments of the present disclosure further provide a display device. Referring to FIG9 , the display device 300 may include the display substrate 100 or the display panel 200 described above. The display device may include, but is not limited to, electronic paper, mobile phones, tablet computers, monitors, laptop computers, digital photo frames, navigation systems, and any other product or component with a display function. It should be understood that this display device has the same beneficial effects as the display substrates provided in the aforementioned embodiments.

[0137] Although some embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined in the claims and their equivalents.

Claims

1. A display substrate, characterized in that, The display substrate includes: a substrate substrate; a pixel defining layer disposed on the substrate substrate; a light-emitting functional layer disposed on a side of the pixel defining layer away from the substrate substrate, wherein the light-emitting functional layer includes a charge generation layer; the pixel defining layer has a plurality of pixel openings, and the plurality of pixel openings define a plurality of sub-pixels, and the plurality of sub-pixels are arranged in an array in a first direction and a second direction; the pixel defining layer includes a pixel defining portion located between two adjacent pixel openings, and the pixel defining portion has an undercut structure on a side facing the pixel opening; wherein the undercut structure includes a first portion, a second portion, and a third portion, the first portion is located on a side of the second portion close to the substrate substrate, and the first portion protrudes a second distance in a direction toward the pixel opening relative to the third portion; the third portion is located on a side of the second portion away from the substrate substrate, and the second portion is indented a first distance in a direction away from the pixel opening relative to the third portion; the display substrate further includes a second electrode layer, and the second electrode layer is located on a side of the light-emitting functional layer away from the substrate substrate; wherein the second electrode layer includes a second sub-portion of the second electrode, and a positive projection of the second sub-portion of the second electrode on the substrate substrate at least partially overlaps a positive projection of the undercut structure on the substrate substrate; and the second electrode layer continuously extends at the undercut structure; wherein a connection line between an edge of the first portion facing the pixel opening direction and an edge of the third portion facing the pixel opening direction forms a first slope angle with the first direction, and a side edge of the second sub-portion of the second electrode facing the pixel opening direction has a second slope angle; wherein the first slope angle is less than the second slope angle.

2. The display substrate according to claim 1, wherein, The first slope angle is less than 30°; and / or, the second distance is greater than twice the first distance.

3. The display substrate according to claim 2, wherein An edge of the first portion facing the pixel opening direction has a third slope angle, an edge of the third portion facing the pixel opening direction has a fourth slope angle, and the third slope angle is less than the fourth slope angle.

4. The display substrate according to any one of claims 1 to 3, wherein, A side edge of the second sub-portion of the second electrode away from the pixel opening direction has a fifth slope angle, and the fifth slope angle is less than the first slope angle.

5. The display substrate according to any one of claims 1-4, wherein, The pixel defining layer includes: a first pixel defining sub-layer, a second pixel defining sub-layer, and a third pixel defining sub-layer that are sequentially stacked in a direction away from the substrate substrate; wherein the first portion is located in the first pixel defining sub-layer, the second portion is located in the second pixel defining sub-layer, and the third portion is located in the third pixel defining sub-layer.

6. The display substrate according to any one of claims 1-5, wherein The display substrate further includes a first electrode layer, and the first electrode layer is located on a side of the pixel defining layer close to the substrate substrate; the display substrate includes a plurality of first electrodes in the first electrode layer, the plurality of first electrodes are arranged in an array in the first direction and the second direction, and positive projections of the plurality of pixel openings on the substrate substrate respectively fall within positive projections of the plurality of first electrodes on the substrate substrate; The pixel defining portion further includes a pixel defining main body portion and a lapping portion. A positive projection of the pixel defining main body portion on the substrate is located between positive projections of two adjacent first electrodes on the substrate. A positive projection of the lapping portion on the substrate overlaps with a positive projection of the first electrode on the substrate. The lapping portion protrudes in a direction away from the substrate with respect to the pixel defining main body portion.

7. The display substrate according to claim 6, wherein, The display substrate further includes a plurality of third electrodes. Among them, the third electrodes are electrically connected to the first electrodes; a positive projection of the third electrodes on the substrate at least partially overlaps with a positive projection of the pixel defining main body portion on the substrate; the third electrodes protrude in a direction close to the substrate with respect to the first electrodes; and the third electrodes protrude a third distance in a direction away from the pixel opening with respect to the first electrodes. Among them, the third distance is greater than the second distance.

8. The display substrate according to claim 7, wherein, A side of the second portion facing the pixel opening direction has a sixth slope angle, a side of the lapping portion away from the pixel opening direction has a seventh slope angle, and a side of the pixel defining main body portion facing the pixel opening direction has an eighth slope angle. Among them, the sixth slope angle is greater than the seventh slope angle; and / or the seventh slope angle is greater than the first slope angle; and / or the first slope angle is greater than the eighth slope angle.

9. The display substrate according to any one of claims 6-8, wherein The first portion, the second portion, and the third portion are all located on a side of the lapping portion facing the pixel opening. A surface of the second portion facing the pixel opening is a curved surface concave towards the pixel defining main body portion.

10. The display substrate according to any one of claims 1-9, wherein, The plurality of sub-pixels include a first sub-pixel and a second sub-pixel adjacent in a first direction or a second direction. The first sub-pixel includes a first pixel opening, and the second sub-pixel includes a second pixel opening; the pixel defining portion includes a pixel defining portion located between the first pixel opening and the second pixel opening. The pixel defining portion has an undercut structure on a first side facing the first pixel opening and a second side facing the second pixel opening. The charge generation layer is disconnected at the undercut structure.

11. The display substrate according to claim 10, wherein, The display substrate includes a first charge generation sub-portion, a second charge generation sub-portion, and a third charge generation sub-portion located at the charge generation layer. A positive projection of the first charge generation sub-portion on the substrate at least partially overlaps with a positive projection of the first pixel opening on the substrate. A positive projection of the second charge generation sub-portion on the substrate at least partially overlaps with a positive projection of the second pixel opening on the substrate. A positive projection of the third charge generation sub-portion on the substrate at least partially overlaps with a positive projection of the pixel defining portion on the substrate. Among them, the first charge generation sub-portion and the third charge generation sub-portion are disconnected at the undercut structure on the first side of the pixel defining portion, and the second charge generation sub-portion and the third charge generation sub-portion are disconnected at the undercut structure on the second side of the pixel defining portion.

12. The display substrate according to claim 6, wherein, The light-emitting functional layer includes a first light-emitting sub-layer and a second light-emitting sub-layer. The first light-emitting sub-layer is located between the first electrode layer and the charge generation layer, and the second light-emitting sub-layer is located on the side of the charge generation layer away from the substrate. Wherein, the first light-emitting sub-layer is used to generate light of a first wavelength, and the second light-emitting sub-layer is used to generate light of a second wavelength. Wherein, the light of the first wavelength includes yellow light or a mixture of red and green light; and / or, the light of the second wavelength includes blue light.

13. The display substrate according to claim 12, wherein, Any two of the second light-emitting sub-layer, the first charge generation sub-part, and the first part of the undercut structure located on the first side of the pixel defining part overlap at least partially in the orthographic projection on the substrate; and / or, Any two of the second light-emitting sub-layer, the second charge generation sub-part, and the first part of the undercut structure located on the second side of the pixel defining part overlap at least partially in the orthographic projection on the substrate.

14. The display substrate according to claim 11, wherein, The second pixel defining sub-layer has a second thickness in a third direction, the third pixel defining sub-layer has a third thickness in the third direction, and the maximum distance from the surface of the first charge generation sub-part or the second charge generation sub-part away from the substrate to the surface of the first electrode layer away from the substrate is a first height. Wherein, the third direction is perpendicular to both the first direction and the second direction, and the sum of the second thickness and the third thickness is greater than the first height.

15. The display substrate according to claim 14, wherein, The second distance is greater than the sum of the second thickness, the third thickness, and 0.5 times the first distance. Wherein, the sum of the second thickness, the third thickness, and 0.5 times the first distance is greater than 1100 Å.

16. The display substrate according to any one of claims 1-15, wherein, The first distance is greater than or equal to 400 Å and less than or equal to 600 Å.

17. The display substrate according to claim 14 or 15, wherein The second thickness is greater than or equal to 300 Å and less than or equal to 600 Å; and / or, The third thickness is greater than or equal to 200 Å.

18. The display substrate according to any one of claims 5-17, wherein, The first pixel defining sub-layer has a first thickness in the third direction, and the first thickness is greater than or equal to 200 Å and less than or equal to 300 Å.

19. As described in claim 18 of the display substrate, the third electrode has a fourth thickness in the third direction, and the first thickness is less than the fourth thickness.

20. The display substrate according to claim 18 or 19, wherein The side of the overlapping part away from the pixel opening direction has a fifth thickness, and the fifth thickness is less than the sum of the first thickness, the second thickness, and the third thickness.

21. The display substrate according to any one of claims 2-20, wherein, The second distance is greater than 0.15 μm.

22. The display substrate according to claim 11, wherein, The third charge generation sub-part includes a first sub-part and a second sub-part. The orthographic projection of the first sub-part on the substrate overlaps at least partially with the orthographic projection of the pixel defining main body part on the substrate, and the orthographic projection of the second sub-part on the substrate overlaps at least partially with the orthographic projection of any one of the overlapping part and the third part on the substrate. In a third direction, the maximum distance from the surface of the first sub - part away from the substrate to the surface of the first electrode layer away from the substrate is a second height, and the maximum distance from the surface of the second sub - part away from the substrate to the surface of the first electrode layer away from the substrate is a third height, and the third height is greater than the second height.

23. The display substrate according to claim 22, wherein, The second height is greater than the first height, and the height difference between the third height and the second height is greater than the height difference between the second height and the first height.

24. The display substrate according to claim 1, wherein, The second electrode layer further includes a first sub - part of the second electrode and a third sub - part of the second electrode. The orthographic projection of the first sub - part of the second electrode on the substrate at least partially overlaps with the orthographic projection of the first electrode on the substrate. The orthographic projection of the second sub - part of the second electrode on the substrate at least partially overlaps with the orthographic projection of the overlapping part on the substrate. And The orthographic projection of the third sub - part of the second electrode on the substrate at least partially overlaps with the orthographic projection of the pixel - defining main body on the substrate. In a third direction, the maximum distance from the surface of the first sub - part of the second electrode away from the substrate to the surface of the first electrode layer away from the substrate is a fourth height, the maximum distance from the surface of the second sub - part of the second electrode away from the substrate to the surface of the first electrode layer away from the substrate is a fifth height, and the maximum distance from the surface of the third sub - part of the second electrode away from the substrate to the surface of the first electrode layer away from the substrate is a sixth height. Wherein, the fifth height is greater than the sixth height, and the sixth height is greater than the fourth height.

25. The display substrate according to claim 24, wherein, The height difference between the fifth height and the sixth height is greater than the height difference between the sixth height and the fourth height.

26. The display substrate according to any one of claims 5-25, wherein, The material of the first pixel defining sublayer includes SiO x ; and / or, The material of the second pixel defining sub-layer includes SiN x ; and / or, The material of the third pixel defining sublayer includes SiO x ; and / or, The material of the second electrode layer includes IZO.

27. A display panel, wherein, The display panel includes the display substrate according to any one of claims 1 to 26.

28. A display device, wherein, The display device includes the display substrate according to any one of claims 1 to 26 or the display panel according to claim 27.

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