Display substrate and preparation method therefor, and display device

Abstract

Provided are a display substrate and a preparation method therefor, and a display device. The display substrate comprises a base substrate and a pixel defining layer, wherein the pixel defining layer has a plurality of pixel openings, the plurality of pixel openings define a plurality of sub-pixels, and the pixel defining layer comprises pixel defining portions each located between two adjacent pixel openings. The pixel defining portions each have an undercut structure on the side facing the pixel openings, and the undercut structure comprises a first portion, a second portion and a third portion, wherein the first portion is located on the side of the second portion close to the base substrate, the first portion protrudes relative to the third portion in a direction facing the pixel openings, the third portion is located on the side of the second portion away from the base substrate, and the second portion is recessed relative to the third portion in a direction away from the pixel openings. The first portion comprises a main body portion, a spacer portion and a first protruding portion, wherein the first protruding portion protrudes relative to the main body portion in a direction away from the base substrate, and the first protrusion portion is located on the side of the first portion close to the pixel openings.

Description

Display substrate, manufacturing method thereof and display device TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of display, and in particular, to a display substrate, a manufacturing method thereof and a display device. BACKGROUND

[0002] Silicon-based organic light-emitting diode (OLED) is a micro display developed in recent years. With mature silicon-based semiconductor process, high PPI (pixel density) and high refresh rate OLED display can be prepared, which is applied in the field of VR (Virtual Reality) and AR (Augmented Reality). Silicon-based OLED can realize color display by using white light + three-color filter, and can realize light superposition by using charge generation layer (CGL) in series with multiple light-emitting layers. However, due to the precision limitation of traditional fine metal mask (FMM), pixel isolation process is needed to realize the isolation between adjacent pixels. How to realize effective isolation between pixels, reduce the leakage between pixels and ensure the power consumption and stability of the display substrate is one of the important research topics for researchers.

[0003] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present disclosure, and therefore can include information that does not constitute prior art known to those skilled in the art. SUMMARY

[0004] In one aspect, a display substrate is provided, comprising:

[0005] a substrate substrate; and

[0006] a pixel definition layer disposed on the substrate substrate, the pixel definition layer having a plurality of pixel openings, the plurality of pixel openings defining a plurality of sub-pixels, the plurality of sub-pixels being arranged in an array along a first direction and a second direction,

[0007] The pixel defining layer includes a pixel defining portion between two adjacent pixel openings, the pixel defining portion has an undercut structure on a side facing the pixel opening, the undercut structure includes a first portion, a second portion and a third portion, the first portion is on a side of the second portion close to the substrate, the first portion protrudes in a direction towards the pixel opening relative to the third portion, the third portion is on a side of the second portion away from the substrate, the second portion is recessed in a direction away from the pixel opening relative to the third portion,

[0008] The first portion includes a main body portion, a raised portion and a first protruding portion, the first protruding portion is on a side of the raised portion away from the substrate, the first protruding portion protrudes in a direction away from the substrate relative to the main body portion.

[0009] The first protruding portion is on a side of the first portion close to the pixel opening.

[0010] According to some exemplary embodiments, the display substrate further includes a light emitting functional layer disposed on a side of the pixel defining layer away from the substrate, the light emitting functional layer includes a first light emitting functional portion at an intersection region of the undercut structure and the pixel opening, the first light emitting functional portion includes a first surface away from the substrate, in a third direction, the first surface is spaced apart from a surface of the substrate close to the pixel defining layer by a first spacing distance, the first spacing distance gradually decreases in a direction of the pixel defining portion pointing to the pixel opening, the third direction is parallel to a light output direction of the display substrate; and

[0011] In the direction of the pixel defining portion pointing to the pixel opening, the first light emitting functional portion has a first width, the first portion protrudes in a direction towards the pixel opening relative to the third portion by a first protruding distance, the first protruding distance is greater than or equal to the first width.

[0012] According to some exemplary embodiments, in the direction of the pixel defining portion pointing to the pixel opening, the first protruding portion has a second width, a ratio of the second width to the first protruding distance is greater than or equal to 2 / 3.

[0013] According to some exemplary embodiments, in the third direction, the first protruding portion has a first thickness, the second portion has a second thickness, the first thickness is less than the second thickness.

[0014] According to some exemplary embodiments, the first protruding portion includes a second surface away from the substrate, the second surface is substantially parallel to the surface of the substrate close to the pixel defining layer.

[0015] According to some exemplary embodiments, the first protruding portion comprises a second surface distanced from the substrate, the second surface is spaced apart from the surface of the substrate proximate to the pixel defining layer by a second spacing distance in the third direction, the second spacing distance gradually increases in a direction of the pixel defining portion pointing to the pixel opening.

[0016] According to some exemplary embodiments, the first protruding distance is greater than or equal to 0.1 microns.

[0017] According to some exemplary embodiments, the light emitting functional layer comprises: a first light emitting sub-layer; a charge generation layer located on a side of the first light emitting sub-layer distanced from the substrate; and a second light emitting sub-layer located on a side of the charge generation layer distanced from the substrate, the first light emitting sub-layer is configured to generate light of a first wavelength, the second light emitting sub-layer is configured to generate light of a second wavelength, the first wavelength is greater than the second wavelength,

[0018] wherein the second light emitting sub-layer comprises a first light emitting sub-portion and a second light emitting sub-portion, a footprint of the first light emitting sub-portion on the substrate at least partially overlaps with a footprint of the pixel defining portion on the substrate, a footprint of the second light emitting sub-portion on the substrate at least partially overlaps with a footprint of the pixel opening on the substrate, the first light emitting sub-portion and the second light emitting sub-portion are disconnected at an intersection region of the undercut structure and the pixel opening.

[0019] According to some exemplary embodiments, a footprint of the elevation portion on the substrate does not overlap with a footprint of the third portion on the substrate; and

[0020] a spacing distance between the elevation portion and the third portion in a direction of the pixel defining portion pointing to the pixel opening is greater than a distance by which the second portion is recessed relative to the third portion in a direction distanced from the pixel opening.

[0021] According to some exemplary embodiments, a spacing distance between the elevation portion and the third portion in a direction of the pixel defining portion pointing to the pixel opening is greater than a spacing distance between the first light emitting sub-portion and the second light emitting sub-portion.

[0022] According to some exemplary embodiments, the charge generation layer comprises a first charge generation sub-portion located at the intersection region of the undercut structure and the pixel opening, the first charge generation sub-portion comprises a third surface distanced from the substrate, the third surface has a convex surface convexly protruding away from the substrate in a direction distanced from the substrate.

[0023] According to some exemplary embodiments, the first charge generation sub-portion comprises a first side edge distal to the pixel opening, and the second light emitting sub-portion comprises a second side edge distal to the pixel opening,

[0024] wherein, in the same sub-pixel, the first side edge is further distal to the pixel opening than the second side edge in a direction along the pixel defining portion pointing to the pixel opening.

[0025] According to some exemplary embodiments, the light emitting functional layer comprises a plurality of first light emitting functional sub-layers between the substrate and the second light emitting sub-layer, at least part of the plurality of first light emitting functional sub-layers comprises a plurality of second protrusions on the first portion, and a projection of the plurality of second protrusions on the substrate at least partially overlaps with a projection of the first protrusions on the substrate.

[0026] In a direction distal to the substrate, the plurality of second protrusions has convex curved surfaces distal to the substrate, and curvatures of the convex curved surfaces of the plurality of second protrusions decrease in turn.

[0027] According to some exemplary embodiments, the light emitting functional layer comprises a plurality of second light emitting functional sub-layers on a side of the second light emitting sub-layer distal to the substrate, at least part of the plurality of second light emitting functional sub-layers comprises a plurality of recesses on the first portion, and the plurality of recesses has concave surfaces close to the substrate,

[0028] wherein, a projection of the plurality of recesses on the substrate at least partially overlaps with a projection of the first protrusions on the substrate.

[0029] In a direction distal to the substrate, curvatures of the concave surfaces of the plurality of recesses decrease in turn.

[0030] According to some exemplary embodiments, one of the plurality of second protrusions distal to the substrate and one of the plurality of recesses close to the substrate directly contact.

[0031] According to some exemplary embodiments, in a plane parallel to a light-out direction of the display substrate, the first protrusion has a first cross-sectional shape, and the first cross-sectional shape comprises at least one of a rectangle, a trapezoid, and a triangle.

[0032] According to some exemplary embodiments, in the third direction, the first protrusion has a first thickness, and the second light emitting sub-layer has a third thickness, and a ratio of the first thickness and the third thickness is greater than or equal to 1 / 2.

[0033] According to some exemplary embodiments, the second surface has a first included angle with a first plane direction, the first included angle being greater than or equal to 45°, the first plane direction being perpendicular to a light-out direction of the display substrate.

[0034] According to some exemplary embodiments, a side of the first protruding portion close to the pixel opening has a first slope angle, a side of the first protruding portion away from the pixel opening has a second slope angle, and the first slope angle is smaller than the second slope angle.

[0035] In another aspect, a display device is provided, which includes the display substrate according to any one of the above.

[0036] In yet another aspect, a method for manufacturing a display substrate is provided, which includes:

[0037] providing a substrate substrate;

[0038] forming a first electrode material layer on one side of the substrate substrate, and performing a patterning process on the first electrode material layer to form a first electrode layer; and

[0039] forming a pixel defining material layer on a side of the first electrode layer away from the substrate substrate, and performing a patterning process on the pixel defining material layer to form a pixel defining layer, wherein the pixel defining layer has a plurality of pixel openings, the pixel defining layer includes a pixel defining portion between two adjacent pixel openings, the pixel defining portion has an undercut structure on a side thereof facing the pixel opening, 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, the first portion protrudes in a direction towards 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, the second portion is recessed in a direction away from the pixel opening relative to the third portion, the first portion includes a main body portion, a raised portion, and a first protruding portion, the first protruding portion is located on a side of the raised portion away from the substrate substrate, the first protruding portion protrudes in a direction away from the substrate substrate relative to the main body portion; and the first protruding portion is located on a side of the first portion close to the pixel opening,

[0040] wherein the forming the pixel defining material layer on the side of the first electrode layer away from the substrate substrate, and performing the patterning process on the pixel defining material layer to form the pixel defining layer includes:

[0041] depositing a layer of first insulating material on a side of the first electrode layer away from the substrate substrate, and performing a patterning process on the first insulating material;

[0042] repeating the steps of depositing a first insulating material and performing a patterning process on the first insulating material n times to form a first portion comprising a first protrusion, n being a positive integer greater than or equal to 3;

[0043] depositing a second insulating material and performing a patterning process on the second insulating material to form a second portion; and

[0044] depositing a third insulating material and performing a patterning process on the third insulating material to form a third portion to form an undercut structure comprising a first protrusion in the pixel defining layer. BRIEF DESCRIPTION OF DRAWINGS

[0045] The above content of the present disclosure and other purposes, features and advantages will be more apparent through the following description of embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0046] FIG. 1 is a partial plan view of a display substrate according to embodiments of the present disclosure;

[0047] FIG. 2 is a structural schematic view of a light emitting device according to some embodiments of the present disclosure;

[0048] FIG. 3A is a cross-sectional schematic view of a display substrate taken along line AA’ in FIG. 1 according to some embodiments of the present disclosure, in which an undercut structure is shown, and FIG. 3B is a cross-sectional schematic view of a display substrate taken along line AA’ in FIG. 1 according to other embodiments of the present disclosure, in which an excircle structure is shown;

[0049] FIG. 4 is a partial cross-sectional schematic view of a display substrate according to some embodiments of the present disclosure, in which a case where a second light emitting sublayer is distorted is shown;

[0050] FIGS. 5A-5C are spectral comparison diagrams of planarized devices and pixelated devices at different voltages according to embodiments of the present disclosure;

[0051] FIG. 6 is a partial cross-sectional schematic view of a display substrate according to embodiments of the present disclosure;

[0052] FIG. 7A is a partial enlarged schematic view of a display substrate in an S2 region in FIG. 6 according to some embodiments of the present disclosure, and FIG. 7B is a partial enlarged schematic view of a display substrate in the S2 region in FIG. 6 according to other embodiments of the present disclosure;

[0053] FIG. 8A is a partial cross-sectional schematic view of a display substrate according to embodiments of the present disclosure, and FIG. 8B is a partial cross-sectional schematic view of a display substrate according to other embodiments of the present disclosure;

[0054] FIG. 9A is a cross-sectional schematic view of a display substrate according to embodiments of the present disclosure, and FIG. 9B is a cross-sectional schematic view of an optimized display substrate according to embodiments of the present disclosure;

[0055] FIG. 10A is a partial light emission schematic diagram of a reference display substrate according to FIG. 9A, and FIG. 10B is a partial light emission schematic diagram of an optimized display substrate according to FIG. 9B;

[0056] FIG. 11A is a low gray scale viewing angle luminance diagram of a reference display substrate according to FIG. 9A, and FIG. 11B is a low gray scale viewing angle luminance diagram of an optimized display substrate according to FIG. 9B;

[0057] FIG. 12 is a light emission efficiency comparison diagram of a blue light emission layer according to a reference display substrate and an optimized display substrate;

[0058] FIG. 13 is a blue light spectrum comparison diagram according to a reference display substrate and an optimized display substrate;

[0059] FIG. 14 is a structural schematic diagram of a display device according to an embodiment of the disclosure; and

[0060] FIG. 15 is a flowchart of a method of manufacturing a display substrate according to an embodiment of the disclosure.

[0061] It should be noted that, for the sake of clarity, the size of a layer, structure, or region in the drawings can be exaggerated or reduced, i.e., the drawings are not necessarily drawn to scale relative to each other. DETAILED DESCRIPTION

[0062] To make the objects, technical solutions, and advantages of the embodiments of the disclosure clearer, the technical solutions of the embodiments of the disclosure will be described clearly and completely below with reference to the drawings of the embodiments of the disclosure. Obviously, the described embodiments are some, but not all, of the embodiments of the disclosure. Based on the described embodiments of the disclosure, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong within the scope of the protection of the disclosure.

[0063] It should be noted that, in the drawings, the size and relative size of elements can be exaggerated for the sake of clarity and / or description. Thus, the size and relative size of the various elements in the drawings are not necessarily drawn to scale relative to each other. In the description and drawings, identical or similar reference numerals indicate identical or similar components.

[0064] Unless otherwise defined, technical terms or scientific terms used in the disclosure should be understood as having the same meaning as commonly understood by a person of ordinary skill in the art. The terms “first”, “second”, and similar terms used in the disclosure do not denote any order, quantity, or importance, but are used to distinguish different constituent parts. The terms “comprise”, “include”, and similar terms mean that the elements or objects before the terms encompass the elements or objects listed after the terms and equivalents thereof, and do not exclude other elements or objects.

[0065] In this document, unless otherwise specified, directional terms such as "upper", "lower", "left", "right", "inner", "outer", and the like are used for convenience with reference to the orientation or positional relationship shown in the drawings, and are merely intended to facilitate the description of the present disclosure, and do not indicate or imply that the device, element or component referred to must have a particular orientation, be constructed or operated in a particular orientation. It should be understood that when the absolute position of the described object changes, the relative positional relationship they represent may also change accordingly. Therefore, these directional terms cannot be understood as a limitation on the present disclosure.

[0066] Those skilled in the art should understand that, in this document, unless otherwise specified, the expression "height" or "thickness" refers to the size along the surface of each film layer arranged perpendicular to the display substrate, i.e. the size along the light-emitting direction of the display substrate, or the size along the normal direction of the display device.

[0067] In this document, the directional expressions "first direction" and "second direction" are used to describe different directions along the pixel unit, for example, the longitudinal direction and the transverse direction of the pixel unit, or the row direction and the column direction of the sub-pixel arrangement. It should be understood that such representation is only an exemplary description, and is not a limitation on the present disclosure.

[0068] The technical terms involved in the present disclosure are briefly described below to help relevant personnel better understand the present scheme.

[0069] Transfer rate: The transfer rate is the ratio of the light-emitting efficiency of the display substrate to the light-emitting efficiency of a reference light-emitting device formed in the same process. Among them, the anode of the reference light-emitting device is an integral electrode, the cathode of the reference light-emitting device is also an integral electrode, and the reference light-emitting device is an integral light-emitting unit, which can exclude the interference of factors such as leakage on the light-emitting efficiency of the reference light-emitting device. The leakage between pixel units in the display substrate can be measured by the transfer rate index, and the higher the transfer rate, the lower the leakage level between pixel units.

[0070] Distortion: Due to the large height difference at the partition structure, the film layer of the evaporation material in the OLED device may have a rapid change in film morphology at the partition structure, forming a distortion. The probability of leakage at the distortion is relatively large.

[0071] Exemplarily, the embodiment of the present disclosure provides a display substrate. Specifically, the display substrate comprises: a substrate substrate; and a pixel defining layer disposed on the substrate substrate, the pixel defining layer has a plurality of pixel openings, the plurality of pixel openings define a plurality of sub-pixels, the plurality of sub-pixels are arranged in a first direction and a second direction. Wherein, the pixel defining layer comprises a pixel defining portion between two adjacent pixel openings, the pixel defining portion has an undercut structure on a side facing the pixel opening, the undercut structure comprises a first part, a second part and a third part, the first part is located on a side of the second part close to the substrate substrate, the first part protrudes in a direction towards the pixel opening relative to the third part; the third part is located on a side of the second part away from the substrate substrate, the second part is recessed in a direction away from the pixel opening relative to the third part. Wherein, the first part comprises a main body part, a raised part and a first protruding part, the first protruding part is located on a side of the raised part away from the substrate substrate, the first protruding part protrudes in a direction away from the substrate substrate relative to the main body part; and the first protruding part is located on a side of the first part close to the pixel opening.

[0072] By designing the undercut structure, the charge generation layer and the light-emitting layer below the charge generation layer can be effectively blocked. By designing the protruding part in the first part, the film layer structure of the intersection area of the undercut structure and the pixel opening is adjusted by the protruding part, and the light-emitting layer above the charge generation layer can be effectively blocked. By using the combination design of the undercut structure and the protruding part, the blocking effect of the multiple film layers of the intersection area of the pixel opening and the undercut structure can be improved, and thus the problems of display substrate leakage, unstable low gray scale light-emitting state of light-emitting device, low efficiency of low gray scale of light-emitting device and the like can be solved, which is beneficial to improve the stability and display effect of the display substrate.

[0073] It should be noted that in the embodiment of the present disclosure, the low gray scale refers to the case that the luminance of the display substrate is low. Wherein, the low gray scale includes the case that the driving voltage just reaches the light-on voltage of the light-emitting device in the display substrate and the case that the driving voltage is slightly higher than the light-on voltage of the light-emitting device in the display substrate.

[0074] FIG. 1 is a partial plan view of a display substrate according to an embodiment of the present disclosure.

[0075] Exemplarily, in some embodiments of the present disclosure, referring to FIG. 1, the display substrate 100 includes a display area AA, and a plurality of sub-pixels SP located in the display area AA. The plurality of sub-pixels are arranged in a first direction X and a second direction Y. The plurality of sub-pixels SP include a first sub-pixel SP1 and a second sub-pixel SP2 adjacent in the first direction X or the second direction Y. The display substrate 100 further includes a pixel definition layer PDL. The pixel definition layer PDL has a plurality of pixel openings VH, and the plurality of pixel openings VH define the plurality of sub-pixels SP. For example, the first sub-pixel SP1 includes a first pixel opening VH1, and the second sub-pixel SP2 includes a second pixel opening VH2. The pixel opening can be an opening area including a light-emitting area.

[0076] It should be noted that although the embodiments of the present disclosure exemplarily show that the pixel opening VH is a square, in some embodiments of the present disclosure, the pixel opening can also be various shapes such as a rectangle, an ellipse, a circle, a triangle, etc.

[0077] Exemplarily, the plurality of sub-pixels SP can include a plurality of light-emitting devices. For example, one sub-pixel includes one light-emitting device.

[0078] In some embodiments, the light-emitting device can include an OLED light-emitting device.

[0079] Exemplarily, in some embodiments of the present disclosure, the display substrate can include a silicon-based OLED display substrate. For example, the silicon-based OLED can realize color display by adopting white light + three-color filtering. The white OLED can include a plurality of light-emitting layers designed in a stack, and different light-emitting layers can generate light of different colors. The light of different colors is mixed to form white light, and further, the formed white light is mixed with a filtering structure to achieve the effect of color display. For example, different light-emitting layers can include a yellow light-emitting layer and a blue light-emitting layer, or a red-green mixed light-emitting layer and a blue light-emitting layer. Through the yellow light and blue light mixed design, or the red-green mixed light and blue light mixed design, white light can be realized.

[0080] FIG. 2 is a structural schematic diagram of a light-emitting device according to some embodiments of the present disclosure.

[0081] Exemplarily, in combination with reference to FIGS. 1 and 2, the display substrate 100 includes a substrate substrate 1 and a first electrode layer 3 disposed on the substrate substrate 1, and the first electrode layer 3 includes a plurality of first electrodes 31 arranged in the first direction X and the second direction Y. The orthographic projections of the plurality of pixel openings VH on the substrate substrate 1 fall into the orthographic projections of the plurality of first electrodes 31 on the substrate substrate 1, respectively. That is, the plurality of first electrodes 31 and the plurality of sub-pixels SP are one-to-one corresponding, and the area of the first electrode is larger than the light-emitting area of the sub-pixel.

[0082] Exemplarily, the light emitting device can include a first electrode 31, a light emitting functional layer 4, and a second electrode 51. For example, the first electrode 31 can be an anode, and the second electrode 51 can be a cathode. The light emitting functional layer 4 can include a plurality of light emitting functional film layers. For example, the light emitting functional layer 4 can include, sequentially away from a substrate, a hole injection layer 41, a first hole transport layer 42, a first light emitting sub-layer 43, a first electron transport layer 44, a charge generation layer (CGL) 45, a second hole transport layer 46, a second light emitting sub-layer 47, a second electron transport layer 48, and an electron injection layer 49.

[0083] Exemplarily, the first light emitting sub-layer 43 can be configured to generate light of a first wavelength, and the second light emitting sub-layer 47 can be configured to generate light of a second wavelength. For example, the light of the first wavelength can include yellow light or red-green mixed light, and the light of the second wavelength can include blue light.

[0084] In some embodiments, the first light emitting sub-layer 43 can include a single film layer formed by mixing and evaporating a host material and a yellow light emitting dye, or the first light emitting sub-layer 43 can include a single film layer formed by mixing and evaporating a host material, a green light emitting dye, and a red light emitting dye, or the first light emitting sub-layer 43 can include a plurality of light emitting film layers. For example, the first light emitting sub-layer can include a film layer formed by mixing and evaporating a host material one and a green light emitting dye, and a film layer formed by mixing and evaporating a host material two and a red light emitting dye. The host material one and the host material two can be the same or different.

[0085] In some embodiments, the second light emitting sub-layer 47 can include a single film layer formed by mixing and evaporating a host material and a blue light emitting dye.

[0086] In a stacked OLED device, due to the high conductivity of the charge generation layer (CGL) 45, when the charge generation layer between adjacent pixels is not blocked, it is easy to cause horizontal crosstalk between the pixels. In order to reduce or eliminate the horizontal crosstalk between the pixels, a blocking structure can be designed between the pixels, so that the charge generation layer is disconnected at the blocking structure, thereby reducing the probability of horizontal crosstalk and facilitating to reduce the electric leakage and improve the stability and display effect of the display substrate.

[0087] FIG. 3A is a cross-sectional view of a display substrate taken along line AA' in FIG. 1, according to some embodiments of the present disclosure, in which an undercut structure is shown, and FIG. 3B is a cross-sectional view of a display substrate taken along line AA' in FIG. 1, according to some other embodiments of the present disclosure, in which an overcut structure is shown.

[0088] Exemplarily, in some embodiments of the present disclosure, the pixel defining part can adopt an undercut structure (also referred to as an inner undercut structure) design or an outer undercut structure (also referred to as an outer undercut structure) design for the partition between pixels. The undercut structure or the outer undercut structure can increase the step at the partition structure, so that the charge generation layer is disconnected at the partition structure.

[0089] Exemplarily, in combination with reference to FIGS. 1 and 3A, the pixel defining layer PDL includes a plurality of pixel defining parts PDL0. The pixel defining part PDL0 can include an undercut structure UDC. 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 the side of the second portion UDC2 away from the substrate 1, and the second portion UDC2 is recessed relative to the third portion UDC3 in a direction away from the pixel opening VH. The first portion UDC1 protrudes relative to the third portion UDC3 in a direction toward the pixel opening VH.

[0090] By designing the undercut structure in the pixel defining part, that is, designing the part of the pixel defining part close to the pixel opening area as a structure with protruding ends and a recessed middle, the pixel defining part can have a better partition effect on the charge generation layer, and the height of the pixel defining layer required is lower. Therefore, the film layer above the pixel defining layer can be made more flat at the edge of the undercut structure, for example, the cathode layer can be made more flat, so that the uniformity of the electric field distribution in the pixel can be improved, and the edge stray light can be reduced.

[0091] In some embodiments, the pixel defining part can be designed with multiple undercut structures in the area facing the plurality of pixel openings. For example, the pixel defining part has an undercut structure on the side facing the first pixel opening VH1, and also has an undercut structure on the side facing the second pixel opening VH2.

[0092] Exemplarily, the undercut structures in the pixel defining part facing different pixel openings can be the same or different. For example, the distance d1 by which the first portion UDC1 of the UDC structure on the side close to the first pixel opening VH1 protrudes relative to the third portion UDC3 in a direction toward the first pixel opening VH1 can be the same as or different from the distance d4 by which the first portion UDC1 of the UDC structure on the side close to the second pixel opening VH2 protrudes relative to the third portion UDC3 in a direction toward the second pixel opening VH2. For another example, the distance d2 by which the second portion UDC2 of the UDC structure on the side close to the first pixel opening VH1 is recessed relative to the third portion UDC3 in a direction away from the first pixel opening VH1 can be the same as or different from the distance d3 by which the second portion UDC2 of the UDC structure on the side close to the second pixel opening VH2 is recessed relative to the third portion UDC3 in a direction away from the second pixel opening VH2.

[0093] By designing the undercut structure at both ends of the pixel defining part, the number of undercut structures between adjacent pixels can be increased, which is beneficial to further reduce the probability of horizontal crosstalk between pixels, thereby improving the display effect of the display substrate.

[0094] Illustratively, continuing to refer to FIG. 3A, the pixel defining layer PDL can include a plurality of pixel defining sub-layers, which can be stacked. For example, the pixel defining layer PDL can include a first pixel defining sub-layer PDL1, a second pixel defining sub-layer PDL2 and a third pixel defining sub-layer PDL3 which are sequentially stacked away from the substrate 1.

[0095] Illustratively, the first portion UDC1 is located in the first pixel defining sub-layer PDL1, the second portion UDC2 is located in the second pixel defining sub-layer PDL2, and the third portion UDC3 is located in the third pixel defining sub-layer PDL3.

[0096] The materials of the plurality of pixel defining sub-layers can be the same or different. For example, the material of the first pixel defining sub-layer PDL1 can include SiO x ; and / or, the material of the second pixel defining sub-layer PDL2 can include SiN x ; and / or, the material of the third pixel defining sub-layer PDL3 includes SiO x . The plurality of pixel defining sub-layers can have different etching rates under the same etching process conditions. For example, the etching rate of the second pixel defining sub-layer PDL2 can be higher than that of the third pixel defining sub-layer PDL3, so that the second portion UDC2 can form a recessed structure relative to the third portion UDC3 in the direction away from the pixel opening in the etching process. By forming the pixel defining part with the undercut structure, the charge generation layer can be effectively blocked, the horizontal crosstalk between pixels can be reduced, the leakage rate can be reduced, the transfer rate of the display substrate can be improved, and the display effect of the display substrate can be improved.

[0097] The depth of the undercut structure will affect the blocking effect of the pixel defining part. Generally speaking, the greater the depth of the undercut structure, that is, the greater the recess distance (e.g., d2 or d3) of the second portion UDC2 relative to the third portion UDC3 in the direction away from the pixel opening in FIG. 3A, the better the blocking effect. However, the design of the recess distance of the second portion UDC2 relative to the third portion UDC3 also needs to take into account the stability of the undercut structure itself and the influence of the etching rates of the materials of the second pixel defining sub-layer and the third pixel defining sub-layer.

[0098] Exemplarily, the undercut structure can be formed by synchronously etching the second pixel-defining sub-layer PDL2 and the third pixel-defining sub-layer PDL3. Due to the limitation of etching rate and film layer support structure, the depth of the undercut structure is affected by the material properties and film thickness of the second pixel-defining sub-layer PDL2 and the third pixel-defining sub-layer PDL3. For example, when the material of the second pixel-defining sub-layer PDL2 is SiN x and the material of the third pixel-defining sub-layer PDL3 is SiO x , preferably, the second portion UDC2 is recessed relative to the third portion UDC3 by a distance greater than or equal to 400 angstroms and less than or equal to 600 angstroms in a direction away from the pixel opening.

[0099] 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 blocking effect of the pixel-defining layer can be improved as much as possible, the leakage current can be reduced, and the transfer rate of the display substrate can be improved.

[0100] Due to the adoption of the undercut structure with two protruding ends and a concave middle, when the pixel-defining portion blocks the charge generation layer, a distance of the concave of the second pixel-defining sub-layer is increased, and thus the height required by the pixel-defining layer is smaller, so that the second electrode layer located above the pixel-defining layer is more gentle, the electric field distribution above the second electrode layer is more uniform, and the in-plane uniformity of the display substrate is improved.

[0101] In some embodiments, by optimizing the design of the undercut structure UDC, the charge generation layer can be blocked at the undercut structure, and the second electrode layer can be continuously connected at the undercut structure UDC, so as to improve the in-plane uniformity of the display substrate.

[0102] Exemplarily, in some embodiments, referring to FIG. 3B, the pixel-defining portion PDL0 can adopt an outer cutting structure OTC. The outer cutting structure OTC refers to a structure in which the pixel-defining portion PDL0 is locally hollowed in the gap region between two adjacent pixel openings VH, forming a structure with a protruding top and a recessed bottom. For example, the outer cutting structure OTC includes a fourth portion OTC1 and a fifth portion OTC2. The fifth portion OTC2 is located on the side of the fourth portion OTC1 away from the substrate 2, and the fifth portion OTC2 protrudes relative to the first portion OTC1 away from the side of the pixel opening VH. Through such a design, the multiple film layers above the pixel-defining portion can be disconnected at the outer cutting structure OTC, so as to reduce the probability of horizontal crosstalk between pixels.

[0103] The inventors have found that although the pixel defining part can isolate the charge generation layer and reduce the lateral crosstalk between adjacent pixels, due to the large film layer step difference in the area of the pixel defining part close to the pixel opening, the multiple film layers (for example, at least part of the multiple film layers such as the hole injection layer 41, the first hole transport layer 42, the first light emitting sub-layer 43, the first electron transport layer 44, the charge generation layer (CGL) 45, the second hole transport layer 46, the second light emitting sub-layer 47, the second electron transport layer 48, and the electron injection layer 49, etc.) located above the pixel defining layer follow the undulation of the pixel defining layer, and part of the film layers are distorted in the intersection area of the pixel defining part and the pixel opening, thereby causing the light emitting device to leak in the edge area of the pixel opening, resulting in uneven light emitting state, poor low gray level stability, slow response of the device from unstable light emitting state to normal light emitting state, low device efficiency, and affecting the display effect of the display substrate.

[0104] In some embodiments, although the undercut structure UDC can reduce the film layer step difference in the area of the pixel defining part close to the pixel opening, and reduce the probability of distortion of part of the film layers above the pixel defining part, compared with the outer tangent structure OTC, there is still a case of distortion of part of the film layers (for example, the second light emitting sub-layer 47) in the intersection area of the pixel defining part and the pixel opening.

[0105] FIG. 4 is a partial cross-sectional schematic view of a display substrate according to some embodiments of the present disclosure, in which a case of distortion of the second light emitting sub-layer is shown, and FIGS. 5A-5C are spectral comparison diagrams of planarized devices and pixelated devices under different voltages according to embodiments of the present disclosure.

[0106] For example, referring to FIG. 4, the second light emitting sub-layer 47 is distorted in the intersection area DS1 of the pixel defining part and the pixel opening. The second light emitting sub-layer 47 includes a first light emitting sub-part 471, a second light emitting sub-part 472, and a third light emitting sub-part 473. The orthographic projection of the first light emitting sub-part 471 on the substrate substrate at least partially overlaps with the orthographic projection of the pixel defining part PDL0 on the substrate substrate, and the orthographic projection of the second light emitting sub-part 472 on the substrate substrate at least partially overlaps with the orthographic projection of the pixel opening VH on the substrate substrate. One end of the third light emitting sub-part 473 is connected to both the first light emitting sub-part 471 and the second light emitting sub-part 472, and the other end of the third light emitting sub-part 473 extends towards the concave area close to the undercut structure (i.e., the area of the second part UDC2 relative to the third part UDC3 in the undercut structure).

[0107] In some embodiments, the first light-emitting sub-layer 43 is a red-green light-emitting layer, and the second light-emitting sub-layer 47 is a blue light-emitting layer. Since the first light-emitting sub-layer 43 is disconnected at the intersection area DS1 of the pixel defining part and the pixel opening, and the second light-emitting sub-layer is distorted at the intersection area DS1 (also referred to as the distortion area) of the pixel defining part and the pixel opening, the first light-emitting sub-part 471 and the second light-emitting sub-part 472 are electrically connected in the distortion area, which may cause the resistance of the light-emitting device near the distortion area to be affected. For example, the resistance of the light-emitting device in the pixel opening area is large, and the resistance of the distortion area is small. The current will preferentially pass through the distortion area, causing the blue light at the edge of the pixel to be turned on first, which may cause the light-emitting state of the device to be non-uniform, the low gray scale stability to be poor, the response of the device to transition from the unstable light-emitting state to the normal light-emitting state to be slow, the device efficiency to be low, and the display effect of the display substrate to be affected.

[0108] For example, in combination with reference to FIGS. 5A-5C, the abscissa is the wavelength, and the ordinate is the relative light output intensity. FIGS. 5A-5C respectively show the relative light output intensity of the pixelated device and the planarized device under different voltages (for example, 5.5V, 6V and 6.5V). The difference between the pixelated device and the planarized device is that the anode of the planarized device is an integral electrode, the cathode of the planarized device is also an integral electrode, and the planarized device is an integral light-emitting unit, which can exclude the interference of factors such as leakage on the light-emitting efficiency of the planarized device. The pixelated device (see FIGS. 1 and 4) includes a plurality of spaced anodes, and pixel defining parts are further arranged between adjacent anodes to separate the pixels. Since the pixel defining part of the pixelated device may cause film layer distortion and edge leakage, the relative light output efficiency of the pixelated device is obviously lower than that of the planarized device under the same voltage. In particular, under low gray scale (for example, under 5.5V voltage), the blue light output efficiency of the pixelated device is obviously lower than that of the planarized device.

[0109] In order to improve the film layer distortion of the intersection area of the pixel defining part and the pixel opening, the undercut structure is further optimized in the embodiments of the present disclosure. By designing a first protruding part near the area of the first part of the undercut structure close to the pixel opening, the topography of at least part of the film layer located above the first part can be regulated, for example, the topography of the second light-emitting sub-layer located in the intersection area of the pixel defining part and the pixel opening can be regulated to avoid distortion of the second light-emitting sub-layer in this area, thereby reducing the probability of leakage of the display substrate, improving the low gray scale blue light phenomenon, and moving the light-emitting boundary to the side of the pixel opening, which is beneficial to improve the transfer rate and light output efficiency of the blue light, increase the color purity of the blue light, and further improve the overall light output efficiency.

[0110] FIG. 6 is a partial cross-sectional schematic view of a display substrate according to embodiments of the present disclosure, FIG. 7A is a partial enlarged schematic view of a display substrate in the S2 region in FIG. 6 according to some embodiments of the present disclosure, and FIG. 7B is a partial enlarged schematic view of a display substrate in the S2 region in FIG. 6 according to other embodiments of the present disclosure.

[0111] Exemplarily, in combination with reference to FIGS. 1, 6, and 7A, the display substrate includes a substrate 1; and a pixel definition layer PDL disposed on the substrate 1, the pixel definition layer PDL has a plurality of pixel openings VH, and the plurality of pixel openings VH define a plurality of sub-pixels SP. The plurality of sub-pixels SP are arranged in an array along a first direction X and a second direction Y. The pixel definition layer PDL includes a pixel definition portion PDL0 between two adjacent pixel openings VH, and the pixel definition portion PDL0 has an undercut structure UDC on a side facing the pixel openings VH.

[0112] The undercut structure UDC includes a first portion UDC1, a second portion UDC2, and a third portion UDC3. The first portion UDC1 is located on a side of the second portion UDC2 close to the substrate 1, and the first portion UDC1 protrudes in a direction toward the pixel openings VH relative to the third portion UDC3. The third portion UDC3 is located on a side of the second portion UDC2 away from the substrate 1, and the second portion UDC2 is recessed in a direction away from the pixel openings relative to the third portion UDC3. The first portion UDC1 includes a main body portion UDC11, a first protruding portion UDC12, and a raised portion UDC13. The first protruding portion UDC12 is located on a side of the raised portion UDC13 away from the substrate 1, and the first protruding portion UDC12 protrudes in a direction away from the substrate 1 relative to the main body portion UDC11; and the first protruding portion UDC12 is located on a side of the first portion close to the pixel openings VH.

[0113] By providing the first protruding portion on the side of the first portion close to the pixel openings, the first protruding portion can adjust the step difference of the film layer above, and can improve the distortion of the light-emitting functional layer in the intersection region of the pixel definition portion and the pixel openings, so that the second light-emitting sub-layer is interrupted in the intersection region, thereby reducing the probability of current leakage of the light-emitting device in the edge region of the pixel openings, and being conducive to improving the problems of unstable low gray scale light-emitting state of the device, low efficiency of the device in low gray scale, and the like, and further can stabilize the low gray scale performance of the display substrate, so that the low gray scale of the display product is more stable and adjustable.

[0114] In some embodiments, the main body portion UDC11, the raised portion UDC13, and the first protruding portion UDC12 can be formed step by step in multiple process steps. For example, the main body portion UDC11 and the raised portion UDC13 can be formed first, and then the first protruding portion UDC12 is formed.

[0115] In order to ensure the adjusting effect of the first part on the upper film layer, the protruding distance of the first part relative to the third part towards the side of the pixel opening is greater than the width of the area where the light-emitting functional layer is prone to distortion, so that the first part can adjust the film layer of the entire distortion area, which is conducive to reducing the leakage probability of the display substrate and improving the low gray scale performance of the display substrate.

[0116] Exemplarily, referring to FIG. 7A, the display substrate further includes the light-emitting functional layer 4 disposed on the side of the pixel definition layer PDL away from the substrate substrate 1.

[0117] Exemplarily, the light-emitting functional layer 4 includes a first light-emitting sub-layer 43, a charge generation layer 45 located on the side of the first light-emitting sub-layer 43 away from the substrate substrate, and a second light-emitting sub-layer 47 located on the side of the charge generation layer 45 away from the substrate substrate. The first light-emitting sub-layer 43 is configured to generate light of a first wavelength, and the second light-emitting sub-layer 47 is configured to generate light of a second wavelength. The first wavelength is greater than the second wavelength. For example, the light of the first wavelength is red-green light, and the light of the second wavelength is blue light.

[0118] The light-emitting functional layer 4 includes a first light-emitting functional part 410 located at the intersection area DS1 of the undercut structure UDC and the pixel opening VH. The first light-emitting functional part 410 includes a first surface 4101 away from the substrate substrate. In the third direction Z, the first surface 4101 is spaced apart from the surface 101 of the substrate substrate 1 close to the pixel definition layer by a first interval distance H1. In the direction of the pixel definition part PDL0 pointing to the pixel opening VH, the first interval distance H1 gradually decreases, and the third direction Z is parallel to the light-emitting direction of the display substrate. For example, the interval distance H11 between one point O1 away from the pixel opening in the first surface 4101 and the surface 101 of the substrate substrate 1 close to the pixel definition layer is greater than the interval distance H12 between one point O2 close to the pixel opening in the first surface 4101 and the surface 101 of the substrate substrate 1 close to the pixel definition layer.

[0119] In the direction of the pixel definition part PDL0 pointing to the pixel opening VH, the first light-emitting functional part 410 has a first width D1. The first part UDC1 protrudes relative to the third part UDC3 in the direction towards the pixel opening by a first protruding distance M1. Exemplarily, the first protruding distance M1 is greater than or equal to the first width D1.

[0120] In some exemplary embodiments, the first protruding distance M1 is greater than or equal to 0.1 microns. For example, the first protruding distance M1 can be about 0.1 microns, 0.11 microns, 0.12 microns, 0.13 microns, or 0.15 microns.

[0121] By such a design, the first part UDC1 can be used to reduce the step difference of the film layer below the area where the first light emitting functional part 410 is located, so as to reduce the probability of distortion of the first light emitting functional part, and further reduce the probability of leakage of the light emitting device in the edge area of the pixel opening, thereby improving the light emitting efficiency and low gray level stability of the light emitting device.

[0122] The inventors have found that, with reference to FIG. 4, the light emitting layer (for example, the second light emitting sublayer 47) above the charge generation layer is prone to distortion near the position of 1 / 3 of the first part UDC1 from the end away from the third part UDC3. For example, in the direction in which the pixel defining part points to the pixel opening, the ratio of the interval distance d5 of the second light emitting sublayer to the first protruding distance M1 is about 1 / 3 at the position of distortion of the second light emitting sublayer, which may result in the formation of the third light emitting subpart 473 in this area, and the first light emitting subpart 471 and the second light emitting subpart 472 are connected through the third light emitting subpart 473, causing the resistance of the edge area of the pixel opening to be small, so that the edge area of the pixel opening is prone to leakage, affecting the low gray level efficiency and stability of the display substrate.

[0123] In order to effectively block the light emitting layer above the charge generation layer, in some embodiments of the present disclosure, a first protruding part is designed on the first part, and the film layer above the first protruding part can be raised, so as to adjust the film layer topography of the light emitting functional layer of the intersection area of the pixel defining part and the pixel opening.

[0124] In some embodiments, by adjusting the width, height and shape of the first protruding part, a targeted adjustment effect can be achieved on the topography of the light emitting functional layer, so that the second light emitting sublayer in the intersection area can be effectively blocked, thereby improving the edge leakage of the device, and improving the low gray level light emitting state stability and the low gray level light emitting efficiency of the device.

[0125] For example, with reference to FIG. 7A, in the direction in which the pixel defining part PDL0 points to the pixel opening VH, the first protruding part UDC12 has a second width D2. The ratio of the second width D2 to the first protruding distance M1 is greater than or equal to 2 / 3. For example, the first protruding distance M1 is about 0.15 microns, and the second width D2 is about 0.12 microns.

[0126] For example, with reference to FIG. 6, in the third direction Z, the first protruding part UDC12 has a first thickness h1, and the second part UDC2 has a second thickness h2.

[0127] Exemplarily, the second thickness h2 is greater than or equal to 300 angstroms and less than or equal to 600 angstroms. For example, the second thickness h2 is about 300 angstroms, 350 angstroms, 400 angstroms, 500 angstroms or 600 angstroms. By optimizing the second thickness h2 of the second portion UDC2, the effect of low gray spectrum regulation of the display substrate can be maintained while effectively blocking the charge generation layer, on the one hand, reducing the leakage rate, improving the transfer rate of the display substrate, improving the efficiency and service life of the display substrate, on the other hand, the spectrum of the display substrate can be regulated, and the display effect of the display substrate is improved.

[0128] Exemplarily, the first thickness h1 is less than the second thickness h2. By optimizing the height relationship of the second portion UDC2 and the first protruding portion UDC12, the morphology of the light emitting functional layer located above the undercut structure can be adjusted, so that the first light emitting sublayer, the charge generation layer and the second light emitting sublayer are all blocked, which is beneficial to reduce the probability of leakage occurrence, thereby improving the stability of the device in low gray light emitting state and improving the low gray light emitting efficiency of the device.

[0129] In some embodiments, the thicker the thickness of the second light emitting sublayer, the thicker the thickness of the first protruding portion required to block the second light emitting sublayer at the intersection area of the pixel defining portion and the pixel opening.

[0130] Exemplarily, referring to FIG. 7A, in the third direction Z, the first protruding portion UDC12 has a first thickness h1, and the second light emitting sublayer 47 has a third thickness h3. The ratio of the first thickness h1 to the third thickness h3 is greater than or equal to 1 / 2. For example, the first thickness h1 is about 50 nanometers, and the third thickness h3 is about 100 nanometers. For another example, the first thickness h1 is about 100 nanometers, and the third thickness h3 is about 150 nanometers.

[0131] Through such a design, the adjustment effect of the first protruding portion on the morphology of the second light emitting sublayer can be improved, thereby achieving the blocking of the second light emitting sublayer at the intersection area of the pixel defining portion and the pixel opening, and reducing the probability of edge leakage of the light emitting device.

[0132] Exemplarily, the second light emitting sublayer 47 includes a first light emitting subportion 471 and a second light emitting subportion 472. The orthographic projection of the first light emitting subportion 471 on the substrate substrate at least partially overlaps with the orthographic projection of the pixel defining portion PDL0 on the substrate substrate, and the orthographic projection of the second light emitting subportion 472 on the substrate substrate at least partially overlaps with the orthographic projection of the pixel opening VH on the substrate substrate. The first light emitting subportion 471 and the second light emitting subportion 472 are disconnected at the intersection area DS1 of the undercut structure UDC and the pixel opening VH.

[0133] In some embodiments, by optimizing the width and height of the first protruding portion, the second light emitting sub-portion 472 located above the first protruding portion can be partially elevated, a step difference is formed between the second light emitting sub-portion 472 and the first light emitting sub-portion 471 located above the pixel defining portion, so that the second light emitting sub-portion 472 and the first light emitting sub-portion 471 can be disconnected, which is conducive to reducing the probability of edge leakage of the light emitting device, improving the low gray scale stability of the display substrate, and improving the low gray scale light emitting efficiency.

[0134] In some embodiments, in a plane parallel to the light emitting direction of the display substrate, the first protruding portion has a first cross-sectional shape, and the first cross-sectional shape includes at least one of a rectangle, a trapezoid, and a triangle. For example, referring to FIG. 6, the first cross-sectional shape includes a rectangle.

[0135] Exemplarily, the first protruding portion UDC12 includes a second surface UDC121 away from the substrate substrate. The second surface UDC121 is substantially parallel to the surface 101 of the substrate substrate close to the pixel defining layer.

[0136] Through such a design, the height and width of the first protruding portion can be conveniently adjusted, so that the adjustment effect of the first protruding portion on the topography of the second light emitting sub-layer can be better controlled, so that the second light emitting sub-layer is disconnected in the intersection area of the pixel defining portion and the pixel opening, which is conducive to reducing the leakage probability of the display substrate and improving the light emitting efficiency and low gray scale stability of the display substrate.

[0137] In some embodiments, the first cross-sectional shape of the first protruding portion can also include a shape similar to a rectangle. For example, the first cross-sectional shape can include a trapezoid; or, a shape similar to a rectangle including a combination of curved edges and right-angled edges.

[0138] Exemplarily, continuing to refer to FIG. 7A, the charge generation layer 45 includes a first charge generation sub-portion 451 located in the intersection area DS1 of the undercut structure and the pixel opening. The first charge generation sub-portion 451 includes a third surface 4510 away from the substrate substrate. In a direction away from the substrate substrate (for example, the third direction Z), the third surface 4510 has a convex arc surface protruding away from the substrate substrate. By designing the first protruding portion, at least part of the film layer located above the first protruding portion can be elevated, so that at least part of the film layer (for example, the charge generation layer) in the light emitting functional layer forms a convex arc surface in this area.

[0139] Exemplarily, the first charge generation sub-layer 451 comprises a first side edge L1 away from the pixel opening, and the second light emitting sub-layer 472 comprises a second side edge L2 away from the pixel opening. Wherein, in the same sub-pixel, in the direction along the pixel defining part PDL0 pointing to the pixel opening VH, the first side edge L1 is farther away from the pixel opening VH than the second side edge L2. Through such a design, it can be ensured that both the charge generation layer and the second light emitting sub-layer are blocked in the intersection area DS1 of the pixel defining part and the pixel opening, which is conducive to reducing the lateral leakage of the display substrate and improving the low gray scale stability of the display substrate.

[0140] Exemplarily, referring to FIG. 7B, the orthographic projection of the raised portion UDC13 on the substrate is not overlapped with the orthographic projection of the third portion UDC3 on the substrate.

[0141] Exemplarily, in the direction of the pixel defining part towards the pixel opening, the interval distance d0 between the raised portion UDC13 and the third portion UDC3 is greater than the distance d2 by which the second portion UDC2 is recessed relative to the third portion UDC3 in the direction away from the pixel opening.

[0142] Through such a design, the recessed second portion UDC2 can be used to increase the film layer step difference of the intersection area of the pixel defining part and the pixel opening, and the first raised portion UDC12 can be used to adjust the film layer topography of the intersection area, so that the blocking effect of the undercut structure on the upper film layer can be improved, and the multiple light emitting layers can be guaranteed to be blocked.

[0143] Exemplarily, continuing to refer to FIG. 7B, in the direction of the pixel defining part towards the pixel opening, the interval distance d0 between the raised portion UDC13 and the third portion UDC3 is greater than the interval distance d6 between the first light emitting sub-layer 471 and the second light emitting sub-layer 472. Wherein, the interval distance d6 between the first light emitting sub-layer 471 and the second light emitting sub-layer 472 refers to the blocking width of the first light emitting sub-layer 471 and the second light emitting sub-layer 472 in the intersection area DS1 of the pixel defining part and the pixel opening.

[0144] By increasing the interval distance between the raised portion UDC13 and the third portion UDC3, the blocking width between the first light emitting sub-layer 471 and the second light emitting sub-layer 472 can be increased, so that the lateral leakage current can be reduced and the light emitting efficiency of the display substrate can be improved.

[0145] Exemplarily, referring to FIG. 7B, the light emitting functional layer 4 comprises a plurality of first light emitting functional sub-layers 411 between the substrate 1 and the second light emitting sub-layer 47. For example, the first light emitting functional sub-layer 411 can comprise a hole injection layer, a first hole transport layer, a first light emitting sub-layer, a first electron transport layer, a charge generation layer, and a second hole transport layer, etc.

[0146] Exemplarily, at least part of the plurality of first light-emitting functional sub-layers 411 comprises a plurality of second protruding portions T411 located on the first portion UDC1. The plurality of second protruding portions T411 has a projection on the substrate substrate which at least partially overlaps with the projection of the first protruding portion UDC12 on the substrate substrate; and in a direction away from the substrate substrate (for example, the third direction Z), the plurality of second protruding portions T411 has a convex arc surface T4110 away from the substrate substrate, and the curvature of the convex arc surface T4110 of the plurality of second protruding portions decreases in turn.

[0147] Exemplarily, the light-emitting functional layer 4 comprises a plurality of second light-emitting functional sub-layers 412 located on the side of the second light-emitting sub-layer 47 away from the substrate substrate. For example, the plurality of second light-emitting functional sub-layers 412 can comprise a second electron transport layer and an electron injection layer, and the like.

[0148] Exemplarily, at least part of the plurality of second light-emitting functional sub-layers 412 comprises a plurality of recessed portions A412 located on the first portion UDC1. The plurality of recessed portions A412 has a plurality of concave surfaces A4120 close to the substrate substrate. Wherein, the plurality of recessed portions A412 has a projection on the substrate substrate which at least partially overlaps with the projection of the first protruding portion UDC12 on the substrate substrate; and in a direction away from the substrate substrate, the curvature of the concave surface of the plurality of recessed portions A4120 decreases in turn.

[0149] Exemplarily, one of the plurality of second protruding portions T411 farthest away from the substrate substrate T4111 and one of the plurality of recessed portions A412 closest to the substrate substrate A4121 are in direct contact.

[0150] Through such a design, the second protruding portions of the plurality of first light-emitting functional sub-layers 411 and the recessed portions of the plurality of second light-emitting functional sub-layers 412 can form a pinch-off structure, so that the second light-emitting sub-layer is blocked at the intersection area DS1 of the undercut structure and the pixel opening, which is beneficial to reduce the lateral leakage of the display substrate and improve the low gray scale stability of the display substrate.

[0151] FIG. 8A is a partial cross-sectional schematic view of a display substrate according to some embodiments of the present disclosure, and FIG. 8B is a partial cross-sectional schematic view of a display substrate according to some other embodiments of the present disclosure.

[0152] Exemplarily, in some embodiments of the present disclosure, the first protruding portion can also adopt a wedge-shaped design. For example, referring to FIG. 8A, the first cross-sectional shape comprises a triangle.

[0153] Exemplarily, the first protruding portion UDC12 includes a second surface UDC121 distal to the substrate substrate. In the third direction Z, the second surface UDC121 is spaced from the surface 101 of the substrate substrate 1 proximate to the pixel defining layer by a second spacing distance H2. In a direction along the pixel defining portion PDL0 pointing to the pixel opening VH, the second spacing distance H2 gradually increases. For example, a point O3 in the second surface UDC121 proximate to the pixel opening is spaced from the surface 101 of the substrate substrate 1 proximate to the pixel defining layer by a distance H21, which is greater than a distance H22 between a point O4 in the second surface UDC121 distal to the pixel opening and the surface 101 of the substrate substrate 1 proximate to the pixel defining layer.

[0154] Exemplarily, in the third direction Z, an apex UDC120 of the first protruding portion UDC12 distal to the substrate substrate is located on a side proximate to the pixel opening VH.

[0155] Exemplarily, a ratio of the second width D2 of the first protruding portion to the first protruding distance M1 is greater than or equal to 2 / 3.

[0156] Exemplarily, the second surface UDC121 has a first included angle θ1 with the first planar direction X1. The first included angle θ1 is greater than or equal to 45°, and the first planar direction X1 is perpendicular to a light-out direction of the display substrate.

[0157] Exemplarily, in combination with reference to FIG. 7A and FIG. 8A, in the third direction Z, the first protruding portion UDC12 has a first thickness h1, and the second light-emitting sub-layer 47 has a third thickness h3. A ratio of the first thickness h1 to the third thickness h3 is greater than or equal to 1 / 2. It should be noted that the first thickness of the first protruding portion here refers to the maximum thickness of the first protruding portion in the third direction.

[0158] By adjusting the thickness of the first protruding portion and the first included angle, the adjusting effect of the first protruding portion on the topography of the second light-emitting sub-layer can be improved, so that the second light-emitting sub-layer is blocked at the intersection area of the pixel defining portion and the pixel opening, which is beneficial to reduce the leakage probability of the display substrate and improve the light-emitting efficiency and low gray scale stability of the display substrate.

[0159] By designing the first protruding portion in the undercut structure, not only the blocking effect between pixels can be improved, but also the blocking requirement for the height of the pixel defining layer can be further reduced, thereby improving the flatness of the second electrode and the light-emitting uniformity of the display substrate.

[0160] In some embodiments of the present disclosure, the first protruding portion can also adopt a prismatic design. For example, with reference to FIG. 8B, the first cross-sectional shape includes a trapezoidal shape.

[0161] Exemplarily, the first protruding part UDC12 has a first slope angle a1 close to one side of the pixel opening VH, and has a second slope angle a2 away from the pixel opening VH, and the first slope angle a1 is smaller than the second slope angle a2.

[0162] Through such a design, the flatness of the film layer in the pixel opening area can be improved while ensuring the partition effect, thereby improving the light emitting uniformity of the display substrate.

[0163] In the embodiments of the present disclosure, in order to further analyze the display difference between the partitioned and non-partitioned second light emitting sub-layers, a set of control display substrates are designed. One set of display substrates (referred to as a reference display substrate S1) adopts an undercut structure but does not have a first protruding part in the undercut structure, and another set of display substrates (referred to as an optimized display substrate S2) adopts an undercut structure, and the first part of the undercut structure is provided with a first protruding part.

[0164] FIG. 9A is a cross-sectional schematic view of a reference display substrate according to an embodiment of the present disclosure, and FIG. 9B is a cross-sectional schematic view of an optimized display substrate according to an embodiment of the present disclosure; FIG. 10A is a partial light emitting schematic view of the reference display substrate according to FIG. 9A, and FIG. 10B is a partial light emitting schematic view of the optimized display substrate according to FIG. 9B; FIG. 11A is a low gray scale viewing angle luminance diagram of the reference display substrate according to FIG. 9A, and FIG. 11B is a low gray scale viewing angle luminance diagram of the optimized display substrate according to FIG. 9B.

[0165] Exemplarily, referring to FIG. 9A, when the undercut structure of the display substrate is not provided with a protruding part, the second light emitting sub-layer located at the intersection area of the pixel defining part and the pixel opening is prone to distortion in this area, resulting in light emission of the second light emitting sub-layer at the distorted area; referring to FIG. 9B, when the first part of the undercut structure of the display substrate is provided with a first protruding part UDC12, the elevation effect of the first protruding part can adjust the topography of the multiple light emitting functional film layers located at the intersection area of the pixel defining part and the pixel opening, so that the second light emitting sub-layer is partitioned in this area.

[0166] It can be found in combination with reference to FIGS. 10A and 10B that, in a low gray scale state, when the second light-emitting sub-layer is not blocked at the intersection of the pixel defining portion and the pixel opening, the edge region of the light-emitting device is first lighted, forming a ring-shaped light-emitting phenomenon as shown in FIG. 10A. The reason is that the part of the second light-emitting sub-layer close to the pixel defining portion (i.e., the edge region) leaks electricity, causing the second light-emitting sub-layer in this region to be lighted first, forming a ring-shaped light-emitting effect as shown in FIG. 10A. This case can cause the light-emitting efficiency of the whole light-emitting device to decrease, and the light-emitting state of the low gray scale is not easy to control, which adversely affects the display effect of the display product. When the second light-emitting sub-layer is blocked at the intersection of the pixel defining portion and the pixel opening, the edge leakage of the second light-emitting sub-layer is alleviated or even eliminated, so that the whole light-emitting device in the pixel opening can be lighted, realizing the whole surface light-emitting effect as shown in FIG. 10B. In this case, it is beneficial to improve the light-emitting efficiency of the light-emitting device, and the brightness adjustment of the light-emitting device is more controllable, thereby improving the low gray scale stability and controllability of the display substrate.

[0167] In the reference display substrate S1, referring to FIG. 9A, the first light-emitting sub-portion 471 located above the pixel defining portion and the second light-emitting sub-portion 472 located above the pixel opening VH are continuous, and the second light-emitting sub-layer leaks electricity at the edge region of the pixel opening, causing abnormal blue light brightness decay in a low gray scale. For example, referring to FIG. 11A, the horizontal coordinate is the visual angle, and the vertical coordinate is the relative brightness. There is obvious warping of the blue light B around 10°, and the brightness decay speed of the blue light is slower than that of the red light R and the green light B in a low gray scale. This can cause low gray scale to be blue in a small visual angle, and the blue sub-pixel edge light-emitting causes the light extraction structure (such as a light enhancement prism) above the blue light to have a reduced light enhancement effect.

[0168] In some embodiments of the present disclosure, by designing the first protruding portion, the second light-emitting sub-layer can be effectively blocked, which is beneficial to improve the consistency of the light-emitting decay speed of different colors and the consistency of the light-emitting area of multiple pixels.

[0169] For example, in the optimized display substrate S2, referring to FIG. 9B, the first light-emitting sub-portion 471 located above the pixel defining portion and the second light-emitting sub-portion 472 located above the pixel opening VH are disconnected, the light-emitting boundary is shifted towards the side close to the pixel opening, and the sub-pixel emits light in the whole surface. Referring to FIG. 11B, the blue light has no warping in a small visual angle, and the brightness decay trends of the red light R, the green light G and the blue light B are close, which is more convenient for controlling the low gray scale state of the display substrate, and the low gray scale state of the display substrate is more stable, which is beneficial to improve the display effect of the display substrate. In addition, the edge light-emitting of the blue light B in a low gray scale is eliminated, which can make the light extraction structure above the blue light have a better light enhancement effect.

[0170] It can be found by referring to FIGS. 9A-11B that when the second light-emitting sub-layer (for example, the blue light-emitting layer) located at the intersection region of the pixel defining portion and the pixel opening in the display substrate is blocked, the probability of the display substrate leaking current is reduced, the low gray scale light-emitting stability is obviously improved, and the stability of the display substrate is improved, the power consumption is reduced, and the display effect is improved.

[0171] FIG. 12 is a comparison diagram of the light-emitting efficiency of the blue light-emitting layer of a reference display substrate and an optimized display substrate.

[0172] Exemplarily, referring to FIG. 12, the abscissa is the current density, and the ordinate is the light-emitting efficiency. When the second light-emitting sub-layer (for example, the blue light-emitting layer) located at the intersection region of the pixel defining portion and the pixel opening in the display substrate is blocked, the distortion of the blue light-emitting layer is reduced, and the low gray scale blue light is weakened. Under the same current density, the light-emitting efficiency of the optimized display substrate S2 is improved by about 27% compared with the light-emitting efficiency of the reference display substrate S1, so that the blue light is enhanced, and the overall light-emitting efficiency of the display substrate is improved.

[0173] FIG. 13 is a comparison diagram of the blue light spectrum of a reference display substrate and an optimized display substrate.

[0174] Exemplarily, referring to FIG. 13, the abscissa is the wavelength, and the ordinate is the relative light-emitting intensity. When the second light-emitting sub-layer (for example, the blue light-emitting layer) located at the intersection region of the pixel defining portion and the pixel opening in the display substrate is blocked, the half peak width of the blue light emitted by the blue light-emitting layer is narrowed (for example, narrowed by about 40%), the edge stray light can be effectively suppressed, the blue light color purity is improved, and the color gamut of the display product is improved.

[0175] FIG. 14 is a structural schematic diagram of a display device according to some embodiments of the present disclosure.

[0176] Optionally, the embodiments of the present disclosure also provide a display device. Referring to FIG. 14, the display device 300 can include the display substrate 100 described above. The display device can include, but is not limited to, electronic paper, mobile phones, tablet computers, displays, notebook computers, digital photo frames, navigation devices, and any product or component with display function. It should be understood that the display device has the same beneficial effects as the display substrate provided by the foregoing embodiments.

[0177] FIG. 15 is a flow chart of a preparation method of a display substrate according to an embodiment of the present disclosure.

[0178] Exemplarily, in some embodiments of the present disclosure, a preparation method of a display substrate is also provided.

[0179] In combination with referring to FIGS. 1, 6, and 15, the preparation method of the display substrate can include the following S01-S03 steps.

[0180] In S01, a substrate 1 is provided.

[0181] In S02, a first electrode material layer is formed on one side of the substrate, and a patterning process is performed on the first electrode material layer to form a first electrode layer 3. For example, a plurality of first electrodes 31 arranged in an array can be formed in the first electrode layer.

[0182] In S03, a pixel defining material layer is formed on the side of the first electrode layer 3 away from the substrate, and a patterning process is performed on the pixel defining material layer to form a pixel defining layer PDL. The pixel defining layer PDL has a plurality of pixel openings VH, and the pixel defining layer PDL includes a pixel defining portion PDL0 located between two adjacent pixel openings VH. The pixel defining portion PDL0 has an undercut structure UDC on the side facing the pixel opening, and the undercut structure UDC includes a first portion UDC1, a second portion UDC2, and a third portion UDC3. The first portion UDC1 is located on the side of the second portion UDC2 close to the substrate, and the first portion UDC1 protrudes in the direction towards the pixel opening relative to the third portion UDC3. The third portion UDC3 is located on the side of the second portion UDC2 away from the substrate, and the second portion UDC2 is recessed in the direction away from the pixel opening relative to the third portion UDC3. The first portion UDC1 includes a main body portion UDC11, a raised portion UDC13, and a first protruding portion UDC12, the first protruding portion UDC12 is located on the side of the raised portion UDC13 away from the substrate, and the first protruding portion UDC12 protrudes in the direction away from the substrate relative to the main body portion UDC11; and the first protruding portion UDC12 is located on the side of the first portion UDC1 close to the pixel opening VH.

[0183] For example, the step of forming a pixel defining layer on the side of the first electrode layer away from the substrate in S03 can include the following S031-S034 steps.

[0184] In S031, a layer of first insulating material is deposited on the side of the first electrode layer away from the substrate, and a patterning process is performed on the first insulating material.

[0185] In S032, the steps of depositing first insulating material and performing a patterning process on the first insulating material are repeated n times to form the first portion UDC1 containing the first protruding portion UDC12, n is a positive integer greater than or equal to 3. For example, n is 3, 4, or 5.

[0186] In S033, a second insulating material is deposited and a patterning process is performed on the second insulating material to form the second portion UDC2.

[0187] In step S034, a third insulating material is deposited and a patterning process is performed on the third insulating material to form a third portion UDC3 to form an undercut structure UDC including the first protrusion UDC12 in the pixel definition layer.

[0188] Exemplarily, the insulating material (e.g., the first insulating material, the second insulating material, and the third insulating material) in the pixel definition layer can include one or more of silicon nitride, silicon oxide, or silicon oxynitride.

[0189] Exemplarily, the preparation method of the display substrate can further include: after the pixel definition layer is formed, continuing to form the light-emitting functional layer and the cathode on a side of the pixel definition layer away from the substrate.

[0190] While some embodiments of the overall inventive concept have been shown and described, it is to be understood that changes can be made in these embodiments without departing from the principles and spirit of the overall inventive concept, the scope of which is defined in the claims and their equivalents.

Claims

1. A display substrate, characterized by, The display substrate comprises: a substrate substrate; and a pixel defining layer disposed on the substrate substrate, the pixel defining layer has a plurality of pixel openings, the plurality of pixel openings define a plurality of sub-pixels, the plurality of sub-pixels are arranged in an array along a first direction and a second direction, wherein the pixel defining layer comprises a pixel defining portion between two adjacent pixel openings, the pixel defining portion has an undercut structure on a side facing the pixel opening, the undercut structure comprises 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, the first portion protrudes in a direction towards 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, the second portion is recessed in a direction away from the pixel opening relative to the third portion, wherein the first portion comprises a main body portion, a raised portion and a first protruding portion, the first protruding portion is located on a side of the raised portion away from the substrate substrate, the first protruding portion protrudes in a direction away from the substrate substrate relative to the main body portion; and the first protruding portion is located on a side of the first portion close to the pixel opening. 2.The display substrate of claim 1, wherein, The display substrate further comprises a light emitting functional layer disposed on a side of the pixel defining layer away from the substrate substrate, the light emitting functional layer comprises a first light emitting functional portion located at an intersection region of the undercut structure and the pixel opening, the first light emitting functional portion comprises a first surface away from the substrate substrate, in a third direction, the first surface is spaced apart from a surface of the substrate substrate close to the pixel defining layer by a first spacing distance, the first spacing distance gradually decreases in a direction of the pixel defining portion pointing to the pixel opening, the third direction is parallel to a light output direction of the display substrate; and in the direction of the pixel defining portion pointing to the pixel opening, the first light emitting functional portion has a first width, the first portion protrudes in a direction towards the pixel opening relative to the third portion by a first protruding distance, the first protruding distance is greater than or equal to the first width. 3.The display substrate of claim 2, wherein, in the direction of the pixel defining portion pointing to the pixel opening, the first protruding portion has a second width, a ratio of the second width to the first protruding distance is greater than or equal to 2 / 3. 4.The display substrate of claim 3, wherein, in the third direction, the first protruding portion has a first thickness, the second portion has a second thickness, the first thickness is less than the second thickness. 5.The display substrate of any one of claims 2-4, wherein, the first protruding portion comprises a second surface away from the substrate substrate, the second surface is substantially parallel to the surface of the substrate substrate close to the pixel defining layer. 6.The display substrate of any one of claims 2-4, wherein, the first protruding portion comprises a second surface away from the substrate substrate, in the third direction, the second surface is spaced apart from the surface of the substrate substrate close to the pixel defining layer by a second spacing distance, the second spacing distance gradually increases in the direction of the pixel defining portion pointing to the pixel opening. 7.The display substrate according to any one of claims 2-6, wherein, the first protruding distance is greater than or equal to 0.1 microns. 8.The display substrate according to any one of claims 2-7, wherein, The light-emitting functional layer comprises: a first light-emitting sub-layer; a charge generation layer located on a side of the first light-emitting sub-layer away from the substrate; and a second light-emitting sub-layer located on a side of the charge generation layer away from the substrate, the first light-emitting sub-layer is configured to generate light of a first wavelength, and the second light-emitting sub-layer is configured to generate light of a second wavelength, the first wavelength being greater than the second wavelength, The second light-emitting sub-layer comprises a first light-emitting sub-sub-layer and a second light-emitting sub-sub-layer, a normal projection of the first light-emitting sub-sub-layer on the substrate at least partially overlaps a normal projection of the pixel defining portion on the substrate, and a normal projection of the second light-emitting sub-sub-layer on the substrate at least partially overlaps a normal projection of the pixel opening on the substrate, the first light-emitting sub-sub-layer and the second light-emitting sub-sub-layer are disconnected at an intersection region of the undercut structure and the pixel opening. 9.The display substrate of claim 8, wherein, A normal projection of the raised portion on the substrate does not overlap a normal projection of the third portion on the substrate; The distance between the raised portion and the third portion in a direction in which the pixel defining portion is directed towards the pixel opening is greater than a distance by which the second portion is recessed relative to the third portion in a direction away from the pixel opening. In the direction in which the pixel defining portion is directed towards the pixel opening, the distance between the raised portion and the third portion is greater than the distance between the first light-emitting sub-sub-layer and the second light-emitting sub-sub-layer. 10.The display substrate of claim 9, wherein, The charge generation layer comprises a first charge generation sub-sub-layer located at the intersection region of the undercut structure and the pixel opening, the first charge generation sub-sub-layer comprises a third surface away from the substrate, and the third surface has a convex curved surface protruding away from the substrate in a direction away from the substrate. 11.The display substrate of claim 9, wherein, The first charge generation sub-sub-layer comprises a first side edge away from the pixel opening, and the second light-emitting sub-sub-layer comprises a second side edge away from the pixel opening, 12.The display substrate of claim 11, wherein, In the same sub-pixel, in the direction in which the pixel defining portion is directed towards the pixel opening, the first side edge is farther away from the pixel opening than the second side edge. The light-emitting functional layer comprises a plurality of first light-emitting functional sub-layers between the substrate and the second light-emitting sub-layer, at least part of the plurality of first light-emitting functional sub-layers comprises a plurality of second protruding portions above the first portion, and a normal projection of the plurality of second protruding portions on the substrate at least partially overlaps a normal projection of the first protruding portion on the substrate; 13.The display substrate of claim 12, wherein, In a direction away from the substrate, the plurality of second protruding portions have convex curved surfaces away from the substrate, and curvatures of the convex curved surfaces of the plurality of second protruding portions decrease in turn. The light-emitting functional layer comprises a plurality of second light-emitting functional sub-layers on a side of the second light-emitting sub-layer away from the substrate, at least part of the plurality of second light-emitting functional sub-layers comprises a plurality of recessed portions above the first portion, and the plurality of recessed portions have a plurality of concave surfaces close to the substrate, ​ 14.The display substrate of claim 13, wherein, ​ The plurality of recessed portions have a projection on the substrate substrate that at least partially overlaps with a projection of the first protruding portion on the substrate substrate. In a direction away from the substrate substrate, the curvature of the concave surface of the plurality of recessed portions decreases in turn. 15.The display substrate of claim 14, wherein, The second protruding portion farthest from the substrate substrate and the recessed portion closest to the substrate substrate directly contact. 16.The display substrate according to any one of claims 1-15, wherein, In a plane parallel to the light-emitting direction of the display substrate, the first protruding portion has a first cross-sectional shape, and the first cross-sectional shape includes at least one of a rectangle, a trapezoid, and a triangle. 17.The display substrate according to any one of claims 9-15, wherein, In the third direction, the first protruding portion has a first thickness, and the second light-emitting sub-layer has a third thickness, and the ratio of the first thickness to the third thickness is greater than or equal to 1 / 2. 18.The display substrate of claim 6, wherein, The second surface has a first included angle with a first plane direction, and the first included angle is greater than or equal to 45°, and the first plane direction is perpendicular to the light-emitting direction of the display substrate.

19. The display substrate of claim 4, wherein, The side of the first protruding portion close to the pixel opening has a first slope angle, and the side of the first protruding portion away from the pixel opening has a second slope angle, and the first slope angle is smaller than the second slope angle.

20. A display device comprising: The display substrate as claimed in any one of claims 1-19.

21. A method for manufacturing a display substrate, comprising: The display substrate comprises: providing a substrate substrate; forming a first electrode material layer on one side of the substrate substrate, and performing a patterning process on the first electrode material layer to form a first electrode layer; and forming a pixel defining material layer on the side of the first electrode layer away from the substrate substrate, and performing a patterning process on the pixel defining material layer to form a pixel defining layer, wherein the pixel defining layer has a plurality of pixel openings, the pixel defining layer includes a pixel defining portion between two adjacent pixel openings, the pixel defining portion has an undercut structure on the side facing the pixel opening, the undercut structure includes a first portion, a second portion and a third portion, the first portion is located on the side of the second portion close to the substrate substrate, and the first portion protrudes in the direction towards the pixel opening relative to the third portion; the third portion is located on the side of the second portion away from the substrate substrate, and the second portion is recessed in the direction away from the pixel opening relative to the third portion, and the first portion includes a main body portion, a raised portion and a first protruding portion, the first protruding portion is located on the side of the raised portion away from the substrate substrate, and the first protruding portion protrudes in the direction away from the substrate substrate relative to the main body portion; and the first protruding portion is located on the side of the first portion close to the pixel opening, wherein the forming of the pixel defining material layer on the side of the first electrode layer away from the substrate substrate and the performing of the patterning process on the pixel defining material layer to form the pixel defining layer comprises: depositing a layer of first insulating material on the side of the first electrode layer away from the substrate substrate, and performing a patterning process on the first insulating material; repeating the steps of depositing a first insulating material and performing a patterning process on the first insulating material n times to form a first portion comprising a first protrusion, n being a positive integer greater than or equal to 3; depositing a second insulating material and performing a patterning process on the second insulating material to form a second portion; and depositing a third insulating material and performing a patterning process on the third insulating material to form a third portion to form an undercut structure comprising a first protrusion in the pixel defining layer.

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