Display substrate, preparation method thereof and display device

Abstract

The invention provides a display substrate, a preparation method thereof and a display device. The display substrate comprises a substrate body and a pixel limiting layer, the pixel limiting layer is provided with a plurality of pixel openings, the pixel openings define a plurality of sub-pixels, and the pixel limiting layer comprises pixel limiting parts located between every two adjacent pixel openings. The side, facing the pixel opening, of the pixel limiting part is provided with an undercut structure, the undercut structure comprises a first part, a second part and a third part, the first part is located on the side, close to the substrate, of the second part, and the first part protrudes in the direction facing the pixel opening relative to the third part; the third part is located on the side, away from the substrate, of the second part, and the second part retracts relative to the third part in the direction away from the pixel opening. The first part comprises a main body part, a heightening part and a first lug boss, and the first lug boss protrudes relative to the main body part in the direction away from the substrate; the first protruding part is located on the side, close to the pixel opening, of the first part.

Description

Technical Field

[0001] The present disclosure relates to the field of display technologies, and in particular, to a display substrate, a preparation method thereof, and a display device. Background Art

[0002] Silicon-based organic light-emitting diodes (OLEDs) are micro displays developed in recent years. With mature silicon-based semiconductor manufacturing processes, OLED displays with high PPI (pixel density) and high refresh rates can be fabricated and applied in the fields of VR (Virtual Reality) and AR (Augmented Reality). Silicon-based OLEDs can achieve color display by using white light + three-color filters, and by using a charge generation layer (CGL) to connect multiple light-emitting layers in series, the effect of light emission superposition can be achieved. However, due to the accuracy limitation of traditional fine metal masks (FMMs), adjacent pixel units need to adopt a pixel isolation process to achieve isolation between pixels. How to effectively isolate pixels, reduce 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 art section is only used to enhance the understanding of the background of the present disclosure, and thus may include information that does not constitute the prior art known to those skilled in the art. Summary of the Invention

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

[0005] A substrate; and

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

[0007] wherein the pixel defining layer includes a pixel defining portion located between two adjacent pixel openings, the pixel defining portion having an undercut structure on a side facing the pixel opening, the undercut structure including a first portion, a second portion, and a third portion, the first portion being located on a side of the second portion close to the substrate, the first portion protruding in a direction towards the pixel opening relative to the third portion, the third portion being located on a side of the second portion away from the substrate, and the second portion being indented in a direction away from the pixel opening relative to the third portion,

[0008] Wherein, the first part includes a main body part, a heightening part, and a first convex part. The first convex part is located on a side of the heightening part away from the substrate, and the first convex part protrudes in a direction away from the substrate relative to the main body part; and

[0009] The first convex part is located on a side of the first part 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 part located in an intersection region of the undercut structure and the pixel opening. The first light-emitting functional part 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, and in a direction pointing from the pixel defining part to the pixel opening, the first spacing distance gradually decreases. The third direction is parallel to a light-emitting direction of the display substrate; and

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

[0012] According to some exemplary embodiments, in a direction pointing from the pixel defining part to the pixel opening, the first convex part has a second width, and 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 convex part has a first thickness, and the second part has a second thickness, and the first thickness is less than the second thickness.

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

[0015] According to some exemplary embodiments, the first convex part includes a second surface away from the substrate. In the third direction, the second surface is spaced apart from a surface of the substrate close to the pixel defining layer by a second spacing distance, and in a direction pointing from the pixel defining part to the pixel opening, the second spacing distance gradually increases.

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

[0017] According to some exemplary embodiments, the light-emitting functional layer includes: a first light-emitting sublayer; a charge generation layer located on a side of the first light-emitting sublayer away from the substrate; and a second light-emitting sublayer located on a side of the charge generation layer away from the substrate. The first light-emitting sublayer is configured to generate light of a first wavelength, and the second light-emitting sublayer is configured to generate light of a second wavelength, where the first wavelength is greater than the second wavelength.

[0018] Wherein, the second light-emitting sublayer includes a first light-emitting sub-portion and a second light-emitting sub-portion. A positive projection of the first light-emitting sub-portion on the substrate at least partially overlaps with a positive projection of the pixel defining portion on the substrate, and a positive projection of the second light-emitting sub-portion on the substrate at least partially overlaps with a positive projection 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 positive projection of the elevation portion on the substrate does not overlap with a positive projection 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 facing the pixel opening is greater than a distance by which the second portion is indented relative to the third portion in a direction away from the pixel opening.

[0021] According to some exemplary embodiments, in a direction of the pixel defining portion facing the pixel opening, a spacing distance between the elevation portion and the third portion 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 includes a first charge generation sub-portion located at an intersection region of the undercut structure and the pixel opening. The first charge generation sub-portion includes a third surface facing away from the substrate, and in a direction away from the substrate, the third surface has a convex arc surface protruding away from the substrate.

[0023] According to some exemplary embodiments, the first charge generation sub-portion includes a first side edge facing away from the pixel opening, and the second light-emitting sub-portion includes a second side edge facing away from the pixel opening.

[0024] Wherein, in the same sub-pixel, in a direction from the pixel defining portion towards the pixel opening, the first side edge is further away from the pixel opening than the second side edge.

[0025] According to some exemplary embodiments, the light-emitting functional layer includes a plurality of first light-emitting functional sub-layers located between the substrate and the second light-emitting sub-layer. At least a portion of the plurality of first light-emitting functional sub-layers includes a plurality of second protrusions located above the first portion. The orthographic projection of the plurality of second protrusions on the substrate at least partially overlaps with the orthographic projection of the first protrusion on the substrate; and

[0026] In a direction away from the substrate, the plurality of second protrusions have convex arc surfaces away from the substrate, and the curvatures of the convex arc surfaces of the plurality of second protrusions decrease in sequence.

[0027] According to some exemplary embodiments, the light-emitting functional layer includes 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 a portion of the plurality of second light-emitting functional sub-layers includes a plurality of recesses located above the first portion. The plurality of recesses have a plurality of concave surfaces close to the substrate,

[0028] wherein the orthographic projection of the plurality of recesses on the substrate at least partially overlaps with the orthographic projection of the first protrusion on the substrate; and

[0029] In a direction away from the substrate, the curvatures of the concave surfaces of the plurality of recesses decrease in sequence.

[0030] According to some exemplary embodiments, a second protrusion that is farthest from the substrate among the plurality of second protrusions is in direct contact with a recess that is closest to the substrate among the plurality of recesses.

[0031] According to some exemplary embodiments, in a plane parallel to the light-emitting direction of the display substrate, the first protrusion has a first cross-sectional shape, and the first cross-sectional shape includes 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. The ratio of the first thickness to 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 the first plane direction, 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.

[0034] According to some exemplary embodiments, one side of the first protrusion near the pixel opening has a first slope angle, and the other side of the first protrusion 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, and the display device includes the display substrate described in any one of the above.

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

[0037] Providing a substrate;

[0038] Forming a first electrode material layer on one side of the 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 the side of the first electrode layer away from the 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 pixel defining portions located 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, and the first portion protrudes in the direction of the pixel opening relative to the third portion; the third portion is located on the side of the second portion away from the substrate, and the second portion is indented in the direction away from the pixel opening relative to the third portion, the first portion includes a main body portion, a heightening portion, and a first protrusion portion, the first protrusion portion is located on the side of the heightening portion away from the substrate, and the first protrusion portion protrudes in the direction away from the substrate relative to the main body portion; and the first protrusion portion is located on the side of the first portion close to the pixel opening,

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

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

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

[0043] Deposit a second insulating material and perform a patterning process on the second insulating material to form a second part; and

[0044] Deposit a third insulating material and perform a patterning process on the third insulating material to form a third part, so as to form an undercut structure including a first protrusion in the pixel defining layer. Description of the Drawings

[0045] Through the following description of the embodiments of the present disclosure with reference to the drawings, the above content and other objects, features and advantages of the present disclosure will become clearer. In the drawings:

[0046] Figure 1 is a partial plan view of a display substrate according to an embodiment of the present disclosure;

[0047] Figure 2 is a schematic structural diagram of a light-emitting device according to some embodiments of the present disclosure;

[0048] Figure 3A is a cross-sectional schematic view of a display substrate according to some embodiments of the present disclosure along Figure 1 the center line AA', which shows an undercut structure, Figure 3B is a cross-sectional schematic view of a display substrate according to other embodiments of the present disclosure along Figure 1 the center line AA', which shows an outer cut structure;

[0049] Figure 4 is a partial cross-sectional schematic view of a display substrate according to some embodiments of the present disclosure, which shows a situation where the second light-emitting sublayer is distorted;

[0050] Figures 5A - 5C is a spectral comparison diagram of a planarization device and a pixelization device under different voltages according to an embodiment of the present disclosure;

[0051] Figure 6 is a partial cross-sectional schematic view of a display substrate according to an embodiment of the present disclosure;

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

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

[0054] Figure 9A is a schematic cross-sectional view of a reference display substrate according to an embodiment of the present disclosure, Figure 9B is a schematic cross-sectional view of an optimized display substrate according to an embodiment of the present disclosure;

[0055] Figure 10A is according to Figure 9A a partial light emission schematic diagram of the reference display substrate, Figure 10B is according to Figure 9B a partial light emission schematic diagram of the optimized display substrate;

[0056] Figure 11A is according to Figure 9A a low gray-scale viewing angle brightness diagram of the reference display substrate, Figure 11B is according to Figure 9B a low gray-scale viewing angle brightness diagram of the optimized display substrate;

[0057] Figure 12 is a comparison diagram of the light emission efficiency of the blue light emitting layers of the reference display substrate and the optimized display substrate;

[0058] Figure 13 is a comparison diagram of the blue light spectra of the reference display substrate and the optimized display substrate;

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

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

[0061] It should be noted that, for clarity, in the drawings used to describe the embodiments of the present invention, the dimensions of layers, structures, or regions may be enlarged or reduced, that is, these drawings are not drawn to actual scale. Detailed Embodiments

[0062] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings of the embodiments of the present disclosure. Apparently, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0063] It should be noted that in the drawings, for clarity and / or for the purpose of description, the dimensions of elements may be enlarged and relative dimensions may be exaggerated. Thus, the dimensions and relative dimensions of the respective elements need not be limited to the dimensions and relative dimensions shown in the figures. In the specification and the drawings, the same or similar reference numerals denote the same or similar components.

[0064] Unless otherwise defined, technical terms or scientific terms used in this disclosure shall have the ordinary meanings as understood by those of ordinary skill in the art. The terms "first", "second" and similar words used in this disclosure do not denote any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0065] In this document, unless otherwise specifically stated, directional terms such as "upper", "lower", "left", "right", "inner", "outer", etc. are used to represent the orientation or positional relationship based on the orientation shown in the drawings, and are only for the convenience of describing this disclosure, rather than indicating or implying that the device, element or component referred to must have a specific orientation, be constructed or operated in a specific orientation. It should be understood that when the absolute position of the object being described changes, the relative positional relationship they represent may also change accordingly. Therefore, these directional terms should not be construed as limitations on this disclosure.

[0066] Those skilled in the art should understand that in this document, unless otherwise stated, the expressions "height" or "thickness" refer to the dimensions along the surfaces of the respective film layers arranged perpendicular to the display substrate, that is, the dimensions along the light-emitting direction of the display substrate, or the dimensions along the normal direction of the display device.

[0067] In this document, 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 representations are only for illustrative description and not limitations on this disclosure.

[0068] The following briefly describes the technical terms involved in this disclosure so that relevant personnel can better understand this solution.

[0069] Transfer rate: The transfer rate is the ratio of the luminous efficiency of the display substrate to the luminous efficiency of a reference light-emitting device formed in the same manufacturing process. Among them, the anode of the reference light-emitting device is a whole-surface electrode, the cathode of the reference light-emitting device is also a whole-surface 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 luminous efficiency of the reference light-emitting device. The transfer rate index can be used to measure the leakage situation between pixel units in the display substrate. 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 evaporation material film layer in the OLED device may have a rapid change in film morphology at the partition structure, forming distortion. The probability of leakage occurring at the distorted part is relatively high.

[0071] Exemplarily, embodiments of the present disclosure provide a display substrate. Specifically, the display substrate includes: a substrate; and a pixel defining layer disposed on the substrate, the pixel defining layer having a plurality of pixel openings, the plurality of pixel openings defining a plurality of sub-pixels, and the plurality of sub-pixels being arranged in an array along a first direction and a second direction. Wherein, the pixel defining layer includes a pixel defining portion located between two adjacent pixel openings, the pixel defining portion having an undercut structure on a side facing the pixel opening, the undercut structure including a first portion, a second portion, and a third portion, the first portion being located on a side of the second portion close to the substrate, the first portion protruding in a direction towards the pixel opening relative to the third portion; the third portion being located on a side of the second portion away from the substrate, the second portion being indented in a direction away from the pixel opening relative to the third portion. Wherein, the first portion includes a main body portion, a heightening portion, and a first protruding portion, the first protruding portion being located on a side of the heightening portion away from the substrate, the first protruding portion protruding in a direction away from the substrate relative to the main body portion; and the first protruding portion being located on a side of the first portion 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 separated. By designing a protruding portion in the first portion and using the protruding portion to regulate the film layer structure at the intersection region of the undercut structure and the pixel opening, the light-emitting layer above the charge generation layer can be effectively separated. By using the combined design of the undercut structure and the protruding portion, the separation effect on multiple film layers at the intersection region of the pixel opening and the undercut structure can be improved, thereby improving problems such as leakage of the display substrate, unstable low gray-scale light-emitting state of the light-emitting device, and low efficiency of the light-emitting device at low gray-scale, which is beneficial to improving the stability and display effect of the display substrate.

[0073] It should be noted that in the embodiments of the present disclosure, low gray-scale refers to a situation where the light-emitting brightness of the display substrate is relatively low. Among them, low gray-scale includes the situation where the driving voltage just reaches the turn-on voltage of the light-emitting device in the display substrate and the situation where the driving voltage is slightly higher than the turn-on voltage of the light-emitting device in the display substrate.

[0074] Figure 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, with reference to Figure 1, the display substrate 100 includes a display area AA and a plurality of sub-pixels SP located within the display area AA. The plurality of sub-pixels are arranged in an array along 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 to each other 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 may be an opening area including a light-emitting region.

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

[0077] Exemplarily, the plurality of sub-pixels SP may 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 may include an OLED light-emitting device.

[0079] Exemplarily, in some embodiments of the present disclosure, the display substrate may include a silicon-based OLED display substrate. For example, the silicon-based OLED may achieve color display by using the method of white light + three-color filtering. The white light OLED may include a plurality of stacked light-emitting layers, and different light-emitting layers may generate different colors of light. White light is formed by mixing different colors of light. Further, the mixed white light is combined with a filtering structure to achieve the effect of color display. For example, different light-emitting layers may include a yellow light-emitting layer and a blue light-emitting layer, or a red-green mixed light-emitting layer and a blue light-emitting layer. White light emission can be achieved through the mixed design of yellow light and blue light, or the mixed design of red-green mixed light and blue light.

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

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

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

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

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

[0085] In some embodiments, the second light-emitting sublayer 47 may include a single film layer formed by co-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 layers between adjacent pixels are not separated, it is easy to cause lateral crosstalk between pixels. To reduce or eliminate the lateral crosstalk between pixels, a separation structure may be designed between the pixels, so that the charge generation layer is disconnected at the separation structure, thereby reducing the probability of lateral crosstalk, which is beneficial to reducing leakage and improving the stability and display effect of the display substrate.

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

[0088] Exemplarily, in some embodiments of the present disclosure, the pixel defining portion may be designed with an undercut structure (also known as an inner cut structure) or an outer cut structure (also known as an outer undercut structure) for partitioning between pixels. By means of the undercut structure or the outer cut structure, the step difference at the partitioning structure can be increased, so that the charge generation layer is disconnected at the partitioning structure.

[0089] Exemplarily, with reference to Figure 1 and Figure 3A , the pixel defining layer PDL includes a plurality of pixel defining portions PDL0. The pixel defining portion PDL0 may include an undercut structure UDC. The undercut structure UDC includes a first portion UDC1, a second portion UDC2, and a third portion UDC3. Among them, 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 indented in a direction away from the pixel opening VH with respect to the third portion UDC3. The first portion UDC1 protrudes in a direction towards the pixel opening VH with respect to the third portion UDC3.

[0090] By designing an undercut structure in the pixel defining portion, that is, designing the portion of the pixel defining portion close to the pixel opening area into a structure with both ends protruding and the middle concave, it is possible to make the pixel defining portion have a better partitioning effect on the charge generation layer, and at the same time, the height of the required pixel defining layer is lower. Therefore, the film layer located above the pixel defining layer can become smoother at the edge of the undercut structure. For example, the cathode layer can become smoother, thereby improving the uniformity of the electric field distribution within the pixel and reducing edge stray light.

[0091] In some embodiments, a plurality of undercut structures may be designed in the area of the pixel defining portion facing the plurality of pixel openings. For example, the pixel defining portion 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 portion facing different pixel openings may 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 VHl protrudes in the direction towards the first pixel opening VH1 with respect to the third portion UDC3 may 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 in the direction towards the second pixel opening VH2 with respect to the third portion UDC3. 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 indented in a direction away from the first pixel opening VH1 with respect to the third portion UDC3 may 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 indented in a direction away from the second pixel opening VH2 with respect to the third portion UDC3.

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

[0094] Exemplarily, continuing to refer to Figure 3A , the pixel defining layer PDL may include a plurality of pixel defining sub-layers, and the plurality of pixel defining sub-layers may be stacked. For example, the pixel defining layer PDL may include: a first pixel defining sub-layer PDL1, a second pixel defining sub-layer PDL2, and a third pixel defining sub-layer PDL3 that are sequentially stacked along the side away from the substrate 1.

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

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

[0097] The depth of the undercut structure will affect the blocking effect of the pixel defining portion. Generally speaking, the depth of the undercut structure, that is, Figure 3A the indentation distance (such as d2 or d3) of the second part UDC2 relative to the third part UDC3 in the direction away from the pixel opening is larger, the better the blocking effect. However, the design of the indentation distance of the second part UDC2 relative to the third part UDC3 also needs to consider the stability of the undercut structure itself and the influence of parameters such as 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 using a synchronous etching process for the second pixel definition sub-layer PDL2 and the third pixel definition sub-layer PDL3. Due to limitations such as etching rate and film support structure, the depth of the undercut structure will be affected by the material properties and film thickness of the second pixel definition sub-layer PDL2 and the third pixel definition sub-layer PDL3. For example, when the material of the second pixel definition sub-layer PDL2 is SiN x , and the material of the third pixel definition sub-layer PDL3 is SiO x , preferably, the indentation distance of the second part UDC2 relative to the third part UDC3 in the direction away from the pixel opening is greater than or equal to 400 Å and less than or equal to 600 Å.

[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 definition layer can be improved as much as possible, reducing leakage and increasing the transfer rate of the display substrate.

[0100] Due to the use of an undercut structure with protruding ends and concave middle, when the pixel definition part blocks the charge generation layer, the distance of the concave section in the second pixel definition sub-layer is increased. Therefore, the height required for the pixel definition layer is smaller, which can make the second electrode layer above the pixel definition layer smoother, and the electric field distribution above the second electrode layer will be more uniform, which is beneficial to improving the in-plane uniformity of the display substrate.

[0101] In some embodiments, through the optimized design of the undercut structure UDC, it can be ensured that while the charge generation layer is blocked at the undercut structure, the second electrode layer is not broken at the undercut structure UDC, thereby improving the in-plane uniformity of the display substrate.

[0102] Exemplarily, in some embodiments, referring to Figure 3B , the pixel definition part PDL0 can adopt an outer cut structure OTC. Among them, the outer cut structure OTC refers to a local hollowing-out design of the pixel definition part PDL0 in the gap area between two adjacent pixel openings VH, forming a structure with a protruding top and a retracted bottom. For example, the outer cut structure OTC includes a fourth part OTC1 and a fifth part OTC2. The fifth part OTC2 is located on the side of the fourth part OTC1 away from the substrate 2, and the fifth part OTC2 protrudes relative to the first part OTC1 on the side away from the pixel opening VH. Through such a design, multiple film layers above the pixel definition part can be disconnected at the outer cut structure OTC, thereby reducing the probability of lateral crosstalk between pixels.

[0103] The inventors have found through research that although the pixel definition part can block 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 definition part close to the pixel opening, multiple film layers (such asFigure 2 At least a part of multiple film layers such as the hole injection layer 41, the first hole transport layer 42, the first light-emitting sublayer 43, the first electron transport layer 44, the charge generation layer (CGL) 45, the second hole transport layer 46, the second light-emitting sublayer 47, the second electron transport layer 48, and the electron injection layer 49 in follows the undulation of the pixel definition layer, and some film layers are distorted in the intersection area of the pixel definition part and the pixel opening, resulting in leakage current at the edge area of the pixel opening of the light-emitting device, leading to uneven light-emitting state of the device, poor low gray-scale stability, slow response of the device from the initial unstable light-emitting state to the normal light-emitting state, low device efficiency, and affecting the display effect of the display substrate.

[0104] In some embodiments, although using the undercut structure UDC can reduce the film layer step difference of the pixel definition part near the pixel opening area compared with using the outer cut structure OTC, and reduce the probability of distortion of some film layers above the pixel definition part, there is still a situation where some film layers (such as the second light-emitting sublayer 47) are distorted in the intersection area of the pixel definition part and the pixel opening.

[0105] Figure 4 is a partial cross-sectional schematic diagram of a display substrate according to some embodiments of the present disclosure, which shows the situation where the second light-emitting sublayer is distorted. Figures 5A - 5C is a spectral comparison diagram of a planarized device and a pixelated device under different voltages according to an embodiment of the present disclosure.

[0106] Exemplarily, in the intersection area DS1 of the pixel definition part and the pixel opening, due to the large film layer step difference of the partition structure (such as the undercut structure UDC), the film layer undulation of at least some film layers in this area is large, and some film layers are prone to distortion in this area. For example, referring to Figure 4 , the second light-emitting sublayer 47 is distorted in the intersection area DS1 of the pixel definition part and the pixel opening. The second light-emitting sublayer 47 includes a first light-emitting subpart 471, a second light-emitting subpart 472, and a third light-emitting subpart 473. Among them, the orthographic projection of the first light-emitting subpart 471 on the substrate at least partially overlaps with the orthographic projection of the pixel definition part PDL0 on the substrate, and the orthographic projection of the second light-emitting subpart 472 on the substrate at least partially overlaps with the orthographic projection of the pixel opening VH on the substrate. One end of the third light-emitting subpart 473 is connected to both the first light-emitting subpart 471 and the second light-emitting subpart 472, and the other end of the third light-emitting subpart 473 extends towards the concave area near the undercut structure (that is, the area where the second part UDC2 of the undercut structure indents relative to the third part UDC3).

[0107] In some embodiments, the first light-emitting sublayer 43 is a red and green light-emitting layer, and the second light-emitting sublayer 47 is a blue light-emitting layer. Since the first light-emitting sublayer 43 is disconnected in the intersection area DS1 of the pixel defining portion and the pixel opening, and the second light-emitting sublayer is distorted in the intersection area DS1 (also called the distortion area) of the pixel defining portion and the pixel opening, the first light-emitting subsection 471 and the second light-emitting subsection 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, while the resistance of the distortion area is small, and the current will preferentially pass through the distortion area, causing the blue light at the edge of the pixel to light up first, which may cause the device to have an uneven light-emitting state, poor low grayscale stability, slow response of the device from the unstable light-emitting state to the normal light-emitting state, and low device efficiency, affecting the display effect of the display substrate.

[0108] For example, in conjunction with reference Figures 5A - 5C , the horizontal axis is the wavelength, and the vertical axis is the relative light intensity. Figures 5A - 5C The comparison of the relative light intensity of the pixelated device and the planar device at different voltages (e.g., 5.5V, 6V, and 6.5V) is shown. The difference between the pixelated device and the planar device is that the anode of the planar device is an electrode on the whole surface, the cathode of the planar device is also an electrode on the whole surface, and the planar device is an integral light-emitting unit, which can eliminate the interference of leakage and other factors on the light-emitting efficiency of the planar device, while the pixelated device (refer to Figure 1 and Figure 4 ) includes a plurality of anodes arranged at intervals, and a pixel defining portion is provided between adjacent anodes for separating pixels. Since the pixel defining portion of the pixelated device may cause film layer distortion and edge leakage, the relative light extraction efficiency of the pixelated device is significantly lower than that of the planar device at the same voltage. In particular, at low grayscale (e.g., at 5.5V voltage), the blue light extraction efficiency of the pixelated device is significantly lower than that of the planar device.

[0109] In order to improve the film layer distortion at the intersection of the pixel defining portion and the pixel opening, the embodiment of the present disclosure further optimizes the design of the undercut structure. By designing a first protrusion in the area of ​​the first part of the undercut structure close to the pixel opening, the morphology of at least part of the film layer located above the first part can be regulated. For example, the morphology of the second light-emitting sublayer located at the intersection of the pixel defining portion and the pixel opening can be regulated to avoid distortion of the second light-emitting sublayer in this area, thereby reducing the probability of leakage of the display substrate and improving the low grayscale blue light phenomenon. At the same time, the light-emitting boundary moves toward the side of the pixel opening, which is conducive to improving the transfer rate and light output efficiency of the blue light, increasing the color purity of the blue light, and thus improving the overall light output efficiency.

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

[0111] Exemplarily, with reference to Figure 1 and Figure 6 and Figure 7A , the display substrate includes a substrate 1; and a pixel defining layer PDL disposed on the substrate, the pixel defining layer PDL having a plurality of pixel openings VH, and the plurality of pixel openings VH defining 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. Among them, the pixel defining layer PDL includes a pixel defining portion PDL0 located between two adjacent pixel openings VH, and the pixel defining portion PDL0 has an undercut structure UDC on a side facing the pixel opening 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 towards the pixel opening VH with respect to the third portion UDC3. The third portion UDC3 is located on a side of the second portion UDC2 away from the substrate, and the second portion UDC2 indents in a direction away from the pixel opening with respect to the third portion UDC3. Among them, the first portion UDC1 includes a main body portion UDC11, a first protrusion portion UDC12, and a heightening portion UDC13. The first protrusion portion UDC12 is located on a side of the heightening portion UDC13 away from the substrate 1, and the first protrusion portion UDC12 protrudes in a direction away from the substrate 1 with respect to the main body portion UDC11; and the first protrusion portion UDC12 is located on a side of the first portion close to the pixel opening VH.

[0113] By providing the first protrusion portion on a side of the first portion close to the pixel opening, the first protrusion portion can adjust the step difference of the upper film layer, can improve the distortion condition of the light-emitting functional layer in the intersection region of the pixel defining portion and the pixel opening, so that the second light-emitting sub-layer is blocked in the intersection region, thereby reducing the probability of leakage of the light-emitting device at the edge region of the pixel opening, which is beneficial to improving problems such as unstable low gray-scale light-emitting state and low efficiency of the device at low gray-scale, and further can stabilize the low gray-scale performance of the display substrate, making the low gray-scale of the display product more stable and adjustable.

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

[0115] To ensure the adjustment effect of the first part on the upper film layer, the protruding distance of the first part relative to the third part toward the pixel opening side should exceed the width of the region where the light-emitting functional layer is prone to distortion, so that the first part can adjust the film layer of the entire distortion region, which is beneficial to reducing the leakage probability of the display substrate and improving the low gray-scale performance of the display substrate.

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

[0117] Exemplarily, the light-emitting functional layer 4 includes: a first light-emitting sublayer 43; a charge generation layer 45 located on the side of the first light-emitting sublayer 43 away from the substrate; and a second light-emitting sublayer 47 located on the side of the charge generation layer 45 away from the substrate. The first light-emitting sublayer 43 is used to generate light of a first wavelength, the second light-emitting sublayer 47 is used to generate light of a second wavelength, and 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 portion 410 located in the intersection region DS1 of the undercut structure UDC and the pixel opening VH. The first light-emitting functional portion 410 includes a first surface 4101 away from the substrate. In the third direction Z, the first surface 4101 is spaced apart from the surface 101 of the substrate 1 close to the pixel defining layer by a first spacing distance H1. In the direction pointing from the pixel defining portion PDL0 to the pixel opening VH, the first spacing distance H1 gradually decreases, and the third direction Z is parallel to the light-emitting direction of the display substrate. For example, the spacing distance H11 between a point O1 on the first surface 4101 away from the pixel opening and the surface 101 of the substrate 1 close to the pixel defining layer is greater than the spacing distance H12 between a point O2 on the first surface 4101 close to the pixel opening and the surface 101 of the substrate 1 close to the pixel defining layer.

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

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

[0121] Through such a design, the first part UDC1 can be used to reduce the step difference of the film layer below the region where the first light-emitting functional part 410 is located, thereby reducing the probability of distortion of the first light-emitting functional part, and further reducing the probability of leakage at the pixel opening edge region of the light-emitting device, which is beneficial to improving the light-emitting efficiency and low gray-scale stability of the light-emitting device.

[0122] The inventor has found through research that: referring to Figure 4 , starting from one end far from the third part UDC3, the light-emitting layer (such as the second light-emitting sub-layer 47) above the charge generation layer is prone to distortion near the 1 / 3 position of the first part UDC1. For example, in the direction from the pixel defining part to the pixel opening, the ratio of the interval distance d5 between the position where the second light-emitting sub-layer is distorted and the third part UDC3 to the first protrusion distance M1 is approximately 1 / 3. In this way, it may cause the formation of a third light-emitting sub-part 473 in this region, and the first light-emitting sub-part 471 and the second light-emitting sub-part 472 are connected through the third light-emitting sub-part 473, resulting in a smaller resistance in the pixel opening edge region, making it easy for the pixel opening edge region to leak electricity, affecting the low gray-scale efficiency and stability of the display substrate.

[0123] In order to effectively isolate the light-emitting layer above the charge generation layer, in some embodiments of the present disclosure, a first protrusion is designed on the first part, which can raise the film layer above the first protrusion, thereby realizing the adjustment of the film layer topography of the light-emitting functional layer in the intersection region of the pixel defining part and the pixel opening.

[0124] In some embodiments, by adjusting the width, height, and shape of the first protrusion, a targeted adjustment effect can be produced on the topography of the upper light-emitting functional layer, so that the second light-emitting sub-layer in this intersection region can be effectively isolated, which is beneficial to improving the edge leakage situation of the device, thereby improving the stability of the low gray-scale light-emitting state of the device and the low gray-scale light-emitting efficiency of the device.

[0125] Exemplarily, referring to Figure 7A , in the direction from the pixel defining part PDL0 to the pixel opening VH, the first protrusion UDC12 has a second width D2. The ratio of the second width D2 to the first protrusion distance M1 is greater than or equal to 2 / 3. For example, the first protrusion distance M1 is approximately 0.15 micrometer, and the second width D2 is approximately 0.12 micrometer.

[0126] Exemplarily, referring to Figure 6In the third direction Z, the first protrusion 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 Å and less than or equal to 600 Å. For example, the second thickness h2 is about 300 Å, 350 Å, 400 Å, 500 Å, or 600 Å. By optimizing the second thickness h2 of the second part UDC2, while effectively isolating the charge generation layer, the effect of low gray-scale spectrum regulation of the display substrate can be maintained. On the one hand, the leakage rate is reduced, the transfer rate of the display substrate is increased, and the efficiency and lifespan of the display substrate are improved. On the other hand, the spectrum of the display substrate can be regulated to enhance the display effect of the display substrate.

[0128] Exemplarily, the first thickness h1 is less than the second thickness h2. By optimizing the height relationship between the second part UDC2 and the first protrusion 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 isolated, which is beneficial to reducing the probability of leakage, thereby improving the stability of the device in the low gray-scale light-emitting state and the low gray-scale light-emitting efficiency of the device.

[0129] In some embodiments, the thicker the second light-emitting sublayer, the thicker the thickness of the first protrusion required to isolate the second light-emitting sublayer at the intersection region of the pixel defining part and the pixel opening.

[0130] Exemplarily, referring to Figure 7A , in the third direction Z, the first protrusion 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 nm, and the third thickness h3 is about 100 nm. For another example, the first thickness h1 is about 100 nm, and the third thickness h3 is about 150 nm.

[0131] Through such a design, the adjustment effect of the first protrusion on the morphology of the second light-emitting sublayer can be improved, thereby realizing the isolation of the second light-emitting sublayer at the intersection region of the pixel defining part 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 subpart 471 and a second light-emitting subpart 472. The orthographic projection of the first light-emitting subpart 471 on the substrate at least partially overlaps with the orthographic projection of the pixel defining part PDL0 on the substrate, and the orthographic projection of the second light-emitting subpart 472 on the substrate at least partially overlaps with the orthographic projection of the pixel opening VH on the substrate. The first light-emitting subpart 471 and the second light-emitting subpart 472 are disconnected at the intersection region DS1 of the undercut structure UDC and the pixel opening VH.

[0133] In some embodiments, by optimizing the width and height of the first protrusion, the second light-emitting sub-part 472 located above the first protrusion can be locally elevated, forming a step difference with the first light-emitting sub-part 471 located above the pixel defining part, so that the second light-emitting sub-part 472 and the first light-emitting sub-part 471 are disconnected, which is beneficial to reducing the probability of edge leakage of the light-emitting device, improving the low gray-scale stability of the display substrate, and increasing 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 protrusion 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 Figure 6 , the first cross-sectional shape includes a rectangle.

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

[0136] Through such a design, it is convenient to adjust the height and width of the first protrusion, so that the adjustment effect of the first protrusion on the morphology of the second light-emitting sub-layer can be better controlled, and the second light-emitting sub-layer is separated in the intersection area of the pixel defining part and the pixel opening, which is beneficial to reducing the leakage probability of the display substrate, 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 protrusion may also include a shape similar to a rectangle. For example, the first cross-sectional shape may include a trapezoid; or, an approximate rectangle shape including a combination of a curved edge and a right angle edge.

[0138] Exemplarily, continuing to refer to Figure 7A , the charge generation layer 45 includes a first charge generation sub-part 451 located in the intersection area DS1 of the undercut structure and the pixel opening. The first charge generation sub-part 451 includes a third surface 4510 away from the substrate. In the direction away from the substrate (e.g., the third direction Z), the third surface 4510 has a convex arc surface protruding away from the substrate. By designing the first protrusion, at least part of the film layer located above the first protrusion can be elevated, so that at least part of the film layer (e.g., 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 - part 451 includes a first side L1 away from the pixel opening, and the second light - emitting sub - part 472 includes a second side L2 away from the pixel opening. Among them, in the same sub - pixel, in the direction from the pixel defining part PDL0 to the pixel opening VH, the first side L1 is farther away from the pixel opening VH than the second side 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 region DS1 of the pixel defining part and the pixel opening, which is beneficial to reducing the lateral leakage of the display substrate and improving the low - gray - scale stability of the display substrate.

[0140] Exemplarily, referring to Figure 7B , the orthographic projection of the elevation part UDC13 on the substrate does not overlap with the orthographic projection of the third part UDC3 on the substrate.

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

[0142] Through such a design, the concave second part UDC2 can be used to increase the film - layer step difference in the intersection region of the pixel defining part and the pixel opening, and at the same time, the first convex part UDC12 can be used to adjust the film - layer morphology of this intersection region, so as to improve the blocking effect of the undercut structure on the upper film layer and ensure that multiple light - emitting layers are blocked.

[0143] Exemplarily, continuing to refer to Figure 7B , in the direction of the pixel defining part towards the pixel opening, the spacing distance d0 between the elevation part UDC13 and the third part UDC3 is greater than the spacing distance d6 between the first light - emitting sub - part 471 and the second light - emitting sub - part 472. Among them, the spacing distance d6 between the first light - emitting sub - part 471 and the second light - emitting sub - part 472 refers to the blocking width of the first light - emitting sub - part 471 and the second light - emitting sub - part 472 in the intersection region DS1 of the pixel defining part and the pixel opening.

[0144] By increasing the spacing distance between the elevation part UDC13 and the third part UDC3, the blocking width between the first light - emitting sub - part 471 and the second light - emitting sub - part 472 can be increased, so as to reduce the lateral leakage current and improve the light - emitting efficiency of the display substrate.

[0145] Exemplarily, referring to Figure 7B , the light - emitting functional layer 4 includes a plurality of first light - emitting functional sub - layers 411 located between the substrate 1 and the second light - emitting sub - layer 47. For example, the first light - emitting functional sub - layer 411 may include multiple film layers such as 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.

[0146] Exemplarily, at least a part of the plurality of first light-emitting functional sub-layers 411 includes a plurality of second protrusions T411 located above the first part UDCl. The orthographic projection of the plurality of second protrusions T411 on the substrate substrate at least partially overlaps with the orthographic projection of the first protrusion UDC12 on the substrate substrate; and in the direction away from the substrate substrate (e.g., the third direction Z), the plurality of second protrusions T411 have convex arc surfaces T4110 away from the substrate substrate, and the curvatures of the convex arc surfaces T4110 of the plurality of second protrusions decrease in sequence.

[0147] Exemplarily, the light-emitting functional layer 4 includes a plurality of second light-emitting functional sub-layers 412 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 may include a plurality of film layers such as a second electron transport layer and an electron injection layer.

[0148] Exemplarily, at least a part of the plurality of second light-emitting functional sub-layers 412 includes a plurality of recesses A412 located above the first part UDCl. The plurality of recesses A412 have a plurality of concave surfaces A4120 close to the substrate substrate. Among them, the orthographic projection of the plurality of recesses A412 on the substrate substrate at least partially overlaps with the orthographic projection of the first protrusion UDC12 on the substrate substrate; and in the direction away from the substrate substrate, the curvatures of the concave surfaces of the plurality of recesses A4120 decrease in sequence.

[0149] Exemplarily, a second protrusion T4111 that is the farthest from the substrate substrate among the plurality of second protrusions T411 and a recess A4121 that is the closest to the substrate substrate among the plurality of recesses A412 are in direct contact.

[0150] Through such a design, a pinch-off structure can be formed by using the second protrusions of the plurality of first light-emitting functional sub-layers 411 and the recesses of the plurality of second light-emitting functional sub-layers 412, so that the second light-emitting sub-layer is cut off at the intersection region DS1 of the undercut structure and the pixel opening, which is beneficial to reducing the lateral leakage of the display substrate and improving the low gray-scale stability of the display substrate.

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

[0152] Exemplarily, in some embodiments of the present disclosure, the first protrusion may also adopt a wedge-shaped design. For example, referring to Figure 8A , the first cross-sectional shape includes a triangle.

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

[0154] Exemplarily, in the third direction Z, the vertex UDC120 of the first protrusion UDC12 farthest from the substrate is located on the side close to the pixel opening VH.

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

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

[0157] Exemplarily, with reference to Figure 7A and Figure 8A , in the third direction Z, the first protrusion UDC12 has a first thickness h1, and the second light-emitting sub-layer 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. It should be noted that the first thickness of the first protrusion here refers to the maximum thickness of the first protrusion in the third direction.

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

[0159] By designing the first protrusion in the undercut structure, not only can the blocking effect between pixels 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 protrusion may also adopt a prismatic design. For example, with reference to Figure 8B , the first cross-sectional shape includes a trapezoid.

[0161] Exemplarily, one side of the first protrusion UDC12 close to the pixel opening VH has a first slope angle α1, and the side of the first protrusion UDC12 away from the pixel opening VH has a second slope angle α2, and the first slope angle α1 is less than the second slope angle α2.

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

[0163] In the embodiments of the present disclosure, in order to further analyze the display differences between the second light-emitting sub-layer being partitioned and not being partitioned, a set of control display substrates was designed. One set of display substrates (referred to as the reference display substrate S1) adopts an undercut structure but no first protrusion is designed in the undercut structure, and another set of display substrates (referred to as the optimized display substrate S2) adopts an undercut structure, and the first part of the undercut structure is provided with a first protrusion.

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

[0165] Exemplarily, referring to Figure 9A , when the undercut structure of the display substrate is not provided with a protrusion, the second light-emitting sub-layer located in 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 part; referring to Figure 9B , when the first part of the undercut structure of the display substrate is provided with a first protrusion UDC12, through the elevation effect of the first protrusion, the morphology of multiple light-emitting functional film layers located in the intersection area of the pixel defining part and the pixel opening can be adjusted, so that the second light-emitting sub-layer is partitioned in this area.

[0166] Combined with referring to Figure 10A and Figure 10B it can be found that: in the low gray-scale state, when the second light-emitting sub-layer is not partitioned in the intersection area of the pixel defining part and the pixel opening, the edge area of the light-emitting device is first lit, forming as Figure 10AThe reason for the annular light-emitting phenomenon shown is that the second light-emitting sub-layer leaks electricity at the part near the pixel defining part (i.e., the edge area), resulting in the second light-emitting sub-layer in this area being turned on first, forming an annular light-emitting effect as shown in Figure 10A This situation will lead to a decrease in the overall luminous efficiency of the light-emitting device, and it is not easy to control the light-emitting state of low gray levels, which has an adverse impact on the display effect of the display product; when the second light-emitting sub-layer is blocked at the intersection area of the pixel defining part and the pixel opening, the edge leakage of the second light-emitting sub-layer is alleviated or even eliminated, so that the light-emitting device in the pixel opening can be turned on as a whole, realizing an overall surface light-emitting effect as shown in Figure 10B In this case, it is beneficial to improve the luminous efficiency of the light-emitting device, and at the same time, the brightness adjustment of the light-emitting device is more controllable, so that the low gray level stability and controllability of the display substrate can be improved.

[0167] In the reference display substrate S1, referring to Figure 9A , the first light-emitting sub-part 471 above the pixel defining part and the second light-emitting sub-part 472 above the pixel opening VH are continuous, and the second light-emitting sub-layer leaks electricity in the edge area of the pixel opening, resulting in abnormal attenuation of the blue light brightness of the light-emitting device at low gray levels. For example, referring to Figure 11A , the abscissa is the viewing angle, the ordinate is the relative brightness, and there is an obvious warp of the blue light B near 10°. The brightness attenuation speed of the blue light at low gray levels is slower than that of the red light R and the green light G, which may lead to a blue shift at low gray levels in a small viewing angle, and the light extraction structure (such as a light enhancement prism) above the blue light has a reduced light enhancement effect due to the edge light emission of the blue sub-pixel.

[0168] In some embodiments of the present disclosure, by designing the first protrusion part, the second light-emitting sub-layer can be effectively blocked, which is beneficial to improving the consistency of the light-emitting attenuation speeds of different colors and the consistency of the light-emitting areas of multiple pixels.

[0169] For example, in the optimized display substrate S2, referring to Figure 9B , the first light-emitting sub-part 471 above the pixel defining part and the second light-emitting sub-part 472 above the pixel opening VH are disconnected, and the light-emitting boundary shifts towards the side close to the pixel opening, and the sub-pixels emit light as a whole. Referring to Figure 11B , there is no warp of the blue light at a small viewing angle, and the brightness attenuation 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 level state of the display substrate, and the low gray level state of the display substrate is more stable, which is beneficial to improving the display effect of the display substrate. In addition, the edge light emission of the blue light B at low gray levels is eliminated, which can make the light enhancement effect of the light extraction structure above the blue light better.

[0170] By referring to Figures 9A - 11BIt can be found that when the second light-emitting sublayer (such as the blue light-emitting layer) in the intersection region of the pixel defining part and the pixel opening in the display substrate is blocked, the probability of leakage of the display substrate decreases, the low gray-scale light-emitting stability is significantly improved, which is beneficial to improving the stability of the display substrate, reducing power consumption, and enhancing the display effect.

[0171] Figure 12 It is a comparison chart of the luminous efficiency of the blue light-emitting layer of the reference display substrate and the optimized display substrate.

[0172] Exemplarily, referring to Figure 12 , the abscissa is the current density and the ordinate is the luminous efficiency. When the second light-emitting sublayer (such as the blue light-emitting layer) in the intersection region of the pixel defining part and the pixel opening in the display substrate is blocked, the distortion of the blue light-emitting layer decreases and the low gray-scale blue light weakens. At the same current density, the luminous efficiency of the optimized display substrate S2 is increased by about 27% compared with that of the reference display substrate S1, so that the light output of the blue light is enhanced, which is beneficial to improving the overall luminous efficiency of the display substrate.

[0173] Figure 13 It is a comparison chart of the blue light spectra of the reference display substrate and the optimized display substrate.

[0174] Exemplarily, referring to Figure 13 , the abscissa is the wavelength and the ordinate is the relative luminous intensity. When the second light-emitting sublayer (such as the blue light-emitting layer) in the intersection region of the pixel defining part and the pixel opening in the display substrate is blocked, the full width at half maximum of the blue light emitted by the blue light-emitting layer narrows (for example, narrows by about 40%), which can effectively suppress the edge stray light, improve the blue light color purity, and further improve the color gamut of the display product.

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

[0176] Optionally, an embodiment of the present disclosure further provides a display device. Referring to Figure 14 , the display device 300 may include the above-mentioned display substrate 100. The display device may include, but is not limited to: any product or component with a display function such as an electronic paper, a mobile phone, a tablet computer, a display, a notebook computer, a digital photo frame, a navigator, etc. It should be understood that the display device has the same beneficial effects as the display substrate provided in the foregoing embodiments.

[0177] Figure 15 It is a flowchart of a method for manufacturing a display substrate according to an embodiment of the present disclosure.

[0178] Exemplarily, in some embodiments of the present disclosure, a method for manufacturing a display substrate is further provided.

[0179] Combined with referring toFigure 1 , Figure 6 and Figure 15 , the method for preparing the display substrate may include the following steps S01 - S03.

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

[0181] In step 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 may be formed in the first electrode layer.

[0182] In step S03, a pixel defining material layer is formed on the side of the first electrode layer away from the substrate, and a patterning process is performed on the pixel defining material layer to form a pixel defining layer PDL. Among them, the pixel defining layer PDL has a plurality of pixel openings VH, and the pixel defining layer PDL includes a pixel defining portion PDL0 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 of 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 indents 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 protrusion portion UDC12. The first protrusion portion UDC12 is located on the side of the raised portion UDC13 away from the substrate, and the first protrusion portion UDC12 protrudes in the direction away from the substrate relative to the main body portion UDC11; and the first protrusion portion UDC12 is located on the side of the first portion UDC1 close to the pixel opening VH.

[0183] Exemplarily, forming a pixel defining material layer on the side of the first electrode layer away from the substrate in step S03 and performing a patterning process on the pixel defining material layer to form a pixel defining layer may include the following steps S031 - S034.

[0184] In step 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 step S032, the steps of depositing the first insulating material and performing a patterning process on the first insulating material are repeated n times to form a first portion UDCl including the first protrusion portion UDC12, where n is a positive integer greater than or equal to 3. For example, n is 3, 4, or 5.

[0186] In step S033, a second insulating material is deposited and a patterning process is performed on the second insulating material to form a second partial 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 partial UDC3, so as to form an undercut structure UDC including a first protruding portion UDC12 in the pixel defining layer.

[0188] Exemplarily, the insulating materials (such as the first insulating material, the second insulating material, and the third insulating material) in the pixel defining layer may include one or more of silicon nitride, silicon oxide, or silicon oxynitride.

[0189] Exemplarily, the method for preparing the display substrate may further include: after forming the pixel defining layer, continuously forming a light-emitting functional layer and a cathode on a side of the pixel defining layer away from the substrate.

[0190] Although some embodiments of the general concept of the present disclosure have been shown and described, those of ordinary skill in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the general concept of the present disclosure, and the scope of the present disclosure is defined by the claims and their equivalents.

Claims

1. A display substrate, characterized in that: include: substrate substrate; and A pixel defining layer is provided on the base substrate, wherein the pixel defining layer has a plurality of pixel openings, wherein the plurality of pixel openings define a plurality of sub-pixels, and the plurality of sub-pixels are arranged in an array along a first direction and a second direction, The pixel defining layer includes a pixel defining portion located between two adjacent pixel openings, the pixel defining portion has an undercut structure on a side facing the pixel opening, the undercut structure includes a first portion, a second portion, and a third portion, the first portion is located on a side of the second portion close to the base substrate, the first portion protrudes relative to the third portion in a direction toward the pixel opening, the third portion is located on a side of the second portion away from the base substrate, and the second portion is retracted relative to the third portion in a direction away from the pixel opening, The first part includes a main body, a raised portion and a first protrusion, the first protrusion is located on a side of the raised portion away from the base substrate, and the first protrusion protrudes relative to the main body in a direction away from the base substrate; and The first protrusion is located on a side of the first portion close to the pixel opening.

2. The display substrate according to claim 1, wherein: The display substrate further comprises a light-emitting function layer disposed on a side of the pixel defining layer away from the base substrate, the light-emitting function layer comprises a first light-emitting function portion located at an intersection of the undercut structure and the pixel opening, the first light-emitting function portion comprises a first surface away from the base substrate, in a third direction, the first surface is spaced apart from a surface of the base substrate close to the pixel defining layer by a first spacing distance, in a direction along the pixel defining portion pointing to the pixel opening, the first spacing distance gradually decreases, and the third direction is parallel to a light emitting direction of the display substrate; and In the direction from the pixel defining portion to the pixel opening, the first light-emitting functional portion has a first width, the first portion protrudes a first protruding distance relative to the third portion in the direction toward the pixel opening, and the first protruding distance is greater than or equal to the first width.

3. The display substrate according to claim 2, wherein: In a direction from the pixel defining portion to the pixel opening, the first protruding portion has a second width, and a ratio of the second width to the first protruding distance is greater than or equal to 2 / 3.

4. The display substrate according to claim 3, wherein: In the third direction, the first protrusion has a first thickness, the second portion has a second thickness, and the first thickness is smaller than the second thickness.

5. The display substrate according to any one of claims 2 to 4, wherein: The first protrusion includes a second surface away from the base substrate, and the second surface is substantially parallel to a surface of the base substrate close to the pixel defining layer.

6. The display substrate according to any one of claims 2 to 4, wherein: The first protrusion includes a second surface away from the base substrate. In the third direction, the second surface is spaced apart from a surface of the base substrate close to the pixel defining layer by a second spacing distance. The second spacing distance gradually increases in a direction along the pixel defining portion pointing to the pixel opening.

7. The display substrate according to any one of claims 2 to 6, wherein: The first protrusion distance is greater than or equal to 0.1 micrometers.

8. The display substrate according to any one of claims 2 to 7, wherein: The light-emitting functional layer comprises: a first light-emitting sublayer; a charge generating layer located on a side of the first light-emitting sublayer away from the substrate; and a second light-emitting sublayer located on a side of the charge generating layer away from the substrate, wherein the first light-emitting sublayer is used to generate light of a first wavelength, and the second light-emitting sublayer is used to generate light of a second wavelength, wherein the first wavelength is greater than the second wavelength. Among them, the second light-emitting sublayer includes a first light-emitting sub-portion and a second light-emitting sub-portion, the orthographic projection of the first light-emitting sub-portion on the substrate at least partially overlaps with the orthographic projection of the pixel defining portion on the substrate, the orthographic projection of the second light-emitting sub-portion on the substrate at least partially overlaps with the orthographic projection of the pixel opening on the substrate, and the first light-emitting sub-portion and the second light-emitting sub-portion are disconnected at the intersection area of ​​the undercut structure and the pixel opening.

9. The display substrate according to claim 8, wherein: The orthographic projection of the raised portion on the base substrate does not overlap with the orthographic projection of the third portion on the base substrate; as well as A distance between the raised portion and the third portion in a direction from the pixel defining portion toward the pixel opening is greater than a distance by which the second portion is retracted relative to the third portion in a direction away from the pixel opening.

10. The display substrate according to claim 9, wherein: In a direction from the pixel defining portion toward the pixel opening, a spacing distance between the raised portion and the third portion is greater than a spacing distance between the first light-emitting sub-portion and the second light-emitting sub-portion.

11. The display substrate according to claim 9, wherein: The charge generating layer includes a first charge generating sub-portion located at the intersection area of ​​the bottom cut structure and the pixel opening, and the first charge generating sub-portion includes a third surface away from the base substrate. In the direction away from the base substrate, the third surface has a convex arc surface protruding away from the base substrate.

12. The display substrate according to claim 11, wherein: The first charge generating subsection includes a first side away from the pixel opening, and the second light emitting subsection includes a second side away from the pixel opening. In the same sub-pixel, in a direction along the pixel defining portion pointing to the pixel opening, the first side is farther away from the pixel opening than the second side.

13. The display substrate according to claim 12, wherein: The light-emitting functional layer comprises a plurality of first light-emitting functional sublayers located between the base substrate and the second light-emitting sublayer, at least a portion of the plurality of first light-emitting functional sublayers comprises a plurality of second protrusions located on the first portion, and the orthographic projections of the plurality of second protrusions on the base substrate at least partially overlap with the orthographic projections of the first protrusions on the base substrate; as well as In a direction away from the base substrate, the plurality of second protrusions have convex arc surfaces away from the base substrate, and the curvatures of the convex arc surfaces of the plurality of second protrusions decrease successively.

14. The display substrate according to claim 13, wherein: The light-emitting functional layer includes a plurality of second light-emitting functional sublayers located on a side of the second light-emitting sublayer away from the base substrate, at least a portion of the plurality of second light-emitting functional sublayers includes a plurality of recessed portions located on the first portion, and the plurality of recessed portions have a plurality of concave surfaces close to the base substrate, wherein the orthographic projections of the plurality of recessed portions on the base substrate at least partially overlap with the orthographic projection of the first protruding portion on the base substrate; and In a direction away from the base substrate, the curvatures of the concave surfaces of the plurality of recessed portions decrease successively.

15. The display substrate according to claim 14, wherein: One of the plurality of second protrusions that is farthest from the base substrate is in direct contact with one of the plurality of recesses that is closest to the base substrate.

16. The display substrate according to any one of claims 1 to 15, wherein: On a plane parallel to the light emitting direction of the display substrate, the first protrusion 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 to 15, wherein: In the third direction, the first protrusion has a first thickness, the second light-emitting sublayer has a third thickness, and a ratio of the first thickness to the third thickness is greater than or equal to 1 / 2.

18. The display substrate according to claim 6, wherein: The second surface has a first angle with the first plane direction, the first 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 according to claim 4, wherein: The side of the first protrusion close to the pixel opening has a first slope angle, and the side of the first protrusion 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, characterized in that: The invention comprises a display substrate as claimed in any one of claims 1 to 19.

21. A method for preparing a display substrate, characterized in that: include: providing a substrate base plate; Forming a first electrode material layer on one side of the base substrate, and performing a patterning process on the first electrode material layer to form a first electrode layer; as well as A pixel defining material layer is formed on a side of the first electrode layer away from the substrate, and a patterning process is performed on the pixel defining material layer to form the pixel defining layer, wherein the pixel defining layer has a plurality of pixel openings, the pixel defining layer includes a pixel defining portion located between two adjacent pixel openings, the pixel defining portion has an undercut structure on a side facing the pixel opening, 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, the first portion protrudes relative to the third portion in a direction toward the pixel opening; the third portion is located on a side of the second portion away from the substrate, the second portion is retracted relative to the third portion in a direction away from the pixel opening, the first portion includes a main body portion, a padding portion and a first protrusion portion, the first protrusion portion is located on a side of the padding portion away from the substrate, the first protrusion portion protrudes relative to the main body portion in a direction away from the substrate; and the first protrusion portion is located on a side of the first portion close to the pixel opening, Wherein, forming a pixel defining material layer on a side of the first electrode layer away from the base substrate, and performing a patterning process on the pixel defining material layer to form the pixel defining layer comprises: Depositing a layer of first insulating material on a side of the first electrode layer away from the 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 for n times to form a first portion including a first protruding portion, where n is 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 A third insulating material is deposited and a patterning process is performed on the third insulating material to form a third portion, so as to form an undercut structure including a first protrusion in the pixel defining layer.

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