Patent Publication Number: US-2022216447-A1

Title: Display substrate, method of manufacturing the same, and display apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national phase entry under 35 USC 371 of International Patent Application No. PCT/CN2020/130921, filed on Nov. 23, 2020, which claims priority to Chinese Patent Application No. 201922114417.1, filed on Nov. 29, 2019, which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the field of display technologies, and in particular, to a display substrate and a method of manufacturing the same, and a display apparatus. 
     BACKGROUND 
     Organic light-emitting diode (OLED) display substrates have advantages of high contrast, thin thickness, wide viewing angle, fast response speed, applicability to a flexible panel, wide temperature range, and the like, and have been widely applied to smart watches, mobile phones, tablet computers, computer monitors and other devices. 
     SUMMARY 
     In an aspect, a display substrate is provided. The display substrate includes a base and a first electrode layer disposed on a side of the base. The first electrode layer includes a transparent conductive layer and a reflective layer. The transparent conductive layer includes a plurality of transparent conductive units that are spaced apart. A transparent conductive unit includes a flat surface in a middle and side faces on peripheries, and an included angle between the flat surface and a side face is an obtuse angle. The reflective layer is located on a side of the transparent conductive layer proximate to the base. The reflective layer includes a plurality of reflective units that are spaced apart, the reflective units and the transparent conductive units are in one-to-one correspondence, and a reflective unit and a corresponding transparent conductive unit are electrically connected; and an orthographic projection of the reflective unit on the base is within a range of an orthographic projection of the flat surface of the corresponding transparent conductive unit on the base. 
     In some embodiments, the first electrode layer further includes: an insulating layer disposed between the reflective layer and the transparent conductive layer. The insulating layer has a plurality of via holes, and each reflective unit and the corresponding transparent conductive unit are electrically connected through a via hole. 
     In some embodiments, a thickness of a portion of the insulating layer located between the transparent conductive unit and the corresponding reflective unit is in a range from approximately 10 nm to approximately 500 nm. 
     In some embodiments, the via hole is filled with tungsten. 
     In some embodiments, the reflective unit includes a metal portion. 
     In some embodiments, a material of the metal portion includes at least one of aluminum, copper, or titanium nitride. 
     In some embodiments, the reflective unit further includes a first protective portion disposed on a side of the metal portion facing away from the transparent conductive layer, and/or a second protective portion disposed on a side of the metal portion proximate to the transparent conductive layer. 
     In some embodiments, the first protective portion includes a first protective sub-portion and/or a second protective sub-portion. A material of the first protective sub-portion includes titanium, and a material of the second protective sub-portion includes titanium nitride. The second protective portion includes a third protective sub-portion and/or a fourth protective sub-portion. A material of the third protective sub-portion includes titanium, and a material of the fourth protective sub-portion includes titanium nitride. 
     In some embodiments, the second protective sub-portion in the first protective portion is closer to the metal portion than the first protective sub-portion in the first protective portion; and/or, the fourth protective sub-portion in the second protective portion is closer to the metal portion than the third protective sub-portion in the second protective portion. 
     In some embodiments, the included angle between any side face and the flat surface of the transparent conductive unit is greater than or equal to approximately 120°. 
     In some embodiments, the display substrate further includes a light-emitting functional layer located on a side of the transparent conductive layer away from the reflective layer; and a second electrode layer located on a side of the light-emitting functional layer away from the transparent conductive layer. 
     In another aspect, a display apparatus is provided. The display apparatus includes the display substrate as described in any of the above embodiments. 
     In some embodiments, the display apparatus is a top-emission display apparatus. 
     In yet another aspect, a method of manufacturing a display substrate is provided. The method includes: providing a base; and forming a first electrode layer on a side of the base. Forming the first electrode layer on the side of the base includes: forming a reflective layer on the side of the base, the reflective layer including a plurality of reflective units that are spaced apart; and forming a transparent conductive layer on a side of the reflective layer away from the base, the transparent conductive layer including a plurality of transparent conductive units that are spaced apart; and a transparent conductive unit including a flat surface in a middle and side faces on peripheries, and an included angle between the flat surface and a side face being an obtuse angle. The reflective units and the transparent conductive units are in one-to-one correspondence, and a reflective unit and a corresponding transparent conductive unit are electrically connected; and an orthographic projection of the reflective unit on the base is within a range of an orthographic projection of the flat surface of the corresponding transparent conductive unit on the base. 
     In some embodiments, after forming the reflective layer and before forming the transparent conductive layer, the method further includes: forming an insulating layer on the base on which the plurality of reflective units are formed; etching the insulating layer to form a plurality of via holes exposing the plurality of reflective units; and filling tungsten in the plurality of via holes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to describe technical solutions in the present disclosure more clearly, the accompanying drawings to be used in some embodiments of the present disclosure will be introduced briefly below. Obviously, the accompanying drawings to be described below are merely accompanying drawings of some embodiments of the present disclosure, and a person of ordinary skill in the art can obtain other drawings according to these drawings. In addition, the accompanying drawings to be described below may be regarded as schematic diagrams, but are not limitations on an actual size of a product, and an actual process of a method involved in the embodiments of the present disclosure. 
         FIG. 1  is a structural diagram of a display substrate, in accordance with some embodiments; 
         FIG. 2  is a cross-sectional diagram of the display substrate in  FIG. 1  taken along the line A-A 1 ; 
         FIG. 3  is a structural diagram of another display substrate, in accordance with some embodiments; 
         FIG. 4  is a structural diagram of yet another display substrate, in accordance with some embodiments; 
         FIG. 5  is a structural diagram of yet another display substrate, in accordance with some embodiments; 
         FIG. 6  is a structural diagram of yet another display substrate, in accordance with some embodiments; 
         FIG. 7  is a structural diagram of yet another display substrate, in accordance with some embodiments; 
         FIG. 8  is a structural diagram of a first overcoat (or a second overcoat), in accordance with some embodiments; 
         FIG. 9  is a structural diagram of yet another display substrate, in accordance with some embodiments; 
         FIG. 10  is a structural diagram of yet another display substrate, in accordance with some embodiments; 
         FIG. 11  is a structural diagram of yet another display substrate, in accordance with some embodiments; 
         FIG. 12  is a structural diagram of a display device, in accordance with some embodiments; 
         FIG. 13  is a flow diagram of a method of manufacturing a display substrate, in accordance with some embodiments; 
         FIG. 14  is a flow diagram of another method of manufacturing a display substrate, in accordance with some embodiments; and 
         FIG. 15  is a flow diagram of yet another method of manufacturing a display substrate, in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Technical solutions in some embodiments of the present disclosure will be described clearly and completely below with reference to the accompanying drawings. Obviously, the described embodiments are merely some but not all embodiments of the present disclosure. All other embodiments obtained on a basis of the embodiments of the present disclosure by a person of ordinary skill in the art shall be included in the protection scope of the present disclosure. 
     Unless the context requires otherwise, throughout the description and the claims, the term “comprise” and other forms thereof such as the third-person singular form “comprises” and the present participle form “comprising” are construed as an open and inclusive meaning, i.e., “including, but not limited to.” In the description of the specification, the terms such as “one embodiment,” “some embodiments,” “exemplary embodiments,” “example,” “specific example” or “some examples” are intended to indicate that specific features, structures, materials or characteristics related to the embodiment(s) or example(s) are included in at least one embodiment or example of the present disclosure. Schematic representations of the above terms do not necessarily refer to the same embodiment(s) or example(s). In addition, the specific features, structures, materials, or characteristics may be included in any one or more embodiments or examples in any suitable manner. 
     Below, the terms “first” and “second” are only used for descriptive purposes, and are not to be construed as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined with “first” or “second” may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, the term “a plurality of”, “the plurality of” or “multiple” means two or more unless otherwise specified. 
     In the description of some embodiments, the terms “coupled” and “connected” and their extensions may be used. For example, the term “connected” may be used in the description of some embodiments to indicate that two or more components are in direct physical or electrical contact with each other. As another example, the term “coupled” may be used in the description of some embodiments to indicate that two or more components are in direct physical or electrical contact. However, the term “coupled” or “communicatively coupled” may also mean that two or more components are not in direct contact with each other, but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the contents herein. 
     The phrase “at least one of A, B and C” has a same meaning as the phrase “at least one of A, B or C”, and they both include the following combinations of A, B and C: only A, only B, only C, a combination of A and B, a combination of A and C, a combination of B and C, and a combination of A, B and C. 
     The phrase “A and/or B” includes the following three combinations: only A, only B, and a combination of A and B. 
     In addition, the use of the phrase “based on” is meant to be open and inclusive, since a process, step, calculation or other action that is “based on” one or more of the stated conditions or values may, in practice, be based on additional conditions or values exceeding those stated. 
     The term “approximately” as used herein includes a stated value and an average value within an acceptable range of deviation of a particular value. The acceptable range of deviation is determined by a person of ordinary skill in the art in view of the measurement in question and the errors associated with the measurement of a particular quantity (i.e., the limitations of a measurement system). 
     Exemplary embodiments are described herein with reference to cross-sectional views and/or plan views as idealized exemplary drawings. In the accompanying drawings, thickness of layers and sizes of regions are enlarged for clarity. Therefore, variations in shape with respect to the accompanying drawings due to, for example, manufacturing technologies and/or tolerances may be envisaged. Therefore, the exemplary embodiments should not be construed as being limited to the shapes of the regions shown herein, but including deviations in the shape due to, for example, manufacturing. For example, an etched region shown in a rectangular shape generally has a curved feature. Therefore, the regions shown in the accompanying drawings are schematic in nature, and their shapes are not intended to show actual shapes of the regions in a device, and are not intended to limit the scope of the exemplary embodiments. 
     In the related art, an organic light-emitting diode (OLED) display substrate includes a base and a light-emitting device layer disposed on a side of the base, and the light-emitting device layer include an anode layer, a light-emitting functional layer, and a cathode layer that are stacked. The anode layer includes a plurality of anodes that are separately disposed, and side faces of each anode form inclined side slopes, so that the light-emitting functional layer and the cathode layer are not easily broken when being evaporated subsequently. However, the inclined side slopes will make a surface of the anode uneven, which will result in poor uniformity of the light-emitting device corresponding to regions of the anode. 
     In order to solve the above problem, in one implementation, a pixel defining layer is provided on the anodes, the pixel defining layer covers the side slopes of the anode, and an opening of the pixel defining layer exposes an even region of the anode. In this way, the light-emitting devices do not emit light in the regions corresponding to the side to slopes of each anode, so that the opening of the pixel defining layer may be used to define a sub-pixel region of an OLED display panel to prevent cross-color in adjacent sub-pixel regions. However, the preparation of the pixel defining layer requires additional process steps, which will result in a complicated manufacturing process of the display substrate and an increase in manufacturing cost. 
     Based on this, some embodiments of the present disclosure provide a display substrate  100 . Referring to  FIGS. 1 and 2 , the display substrate  100  includes a base  10  and a first electrode layer  12  disposed on a side of the base  10 . The first electrode layer  12  may be used to replace the anode layer in the light-emitting device layer described above. On this basis, for example, as shown in  FIG. 3 , the display substrate  100  may further include a light-emitting functional layer  14  and a second electrode layer  15  that are sequentially disposed on a side of the first electrode layer  12  facing away from the base  10 , so as to constitute light-emitting devices used to display images. It will be understood that in a case where the first electrode layer  12  is an anode layer, the second electrode layer  15  is a cathode layer. 
     The first electrode layer  12  includes a reflective layer  12 A and a transparent conductive layer  12 B that are sequentially stacked on the base  10 . 
     The transparent conductive layer  12 B includes a plurality of transparent conductive units  122  that are spaced apart. A surface of a transparent conductive unit  122  facing away from the base  10  is a raised face that is flat in a middle and inclined at obtuse angles on sides, and a flat portion of the raised face is a flat surface  1221 . That is, the transparent conductive unit  122  includes the flat surface  1221  in the middle and side faces  1222  on peripheries, and an included angle between the flat surface  1221  and a side face  1222  is an obtuse angle. This arrangement enables subsequent layers (e.g., the light-emitting functional layer  14 , the second electrode layer  15 ) to be unlikely to be broken during a formation process. In addition, the display substrate  100  may emit light uniformly in a region corresponding to the flat surface  1221 . 
     The reflective layer  12 A includes a plurality of reflective units  121  that are spaced apart. The reflective units  121  and the transparent conductive units  122  are in one-to-one correspondence, and a reflective unit  121  and a corresponding transparent conductive unit  122  are electrically connected. An orthographic projection of the reflective unit  121  on the base  10  is within a range of an orthographic projection of the flat surface  1221  of the corresponding transparent conductive unit  122  on the base  10 . 
     This arrangement enables that the orthographic projection of the reflective unit  121  on the base  10  is not beyond the orthographic projection of the corresponding flat surface  1221  on the base  10 . In this way, when the light-emitting functional layer  14  emits light, light to the first electrode layer  12  in a direction perpendicular from the light-emitting functional layer  14  to the base  10  (e.g., a direction X in  FIG. 3 ) and a small amount of small-angle light in a direction toward the first electrode layer  12 , both emitted by a portion of the light-emitting functional layer  14  that overlaps an orthographic projection of the reflective layer  12 A on the base  10 , may be reflected by the reflective layer  12 A. Light emitted by a portion of the light-emitting functional layer  14  that does not overlap the reflective layer  12 A may hardly be reflected by the reflective layer  12 A. As a result, a problem of non-uniform light emission may be improved. 
     Moreover, when the light-emitting functional layer  14  emits light, large-angle light, emitted in the direction toward the first electrode layer  12  by the portion of the light-emitting functional layer  14  that overlaps the orthographic projection of the reflective layer  12 A on the base  10  may hardly be reflected by the reflective layer  12 A. Therefore, the pixel defining layer in the related art may be replaced, process steps of manufacturing the pixel defining layer may be omitted, and the manufacturing process of the display substrate  100  may be simplified, which is beneficial to lower the manufacturing cost. 
     In some embodiments, referring to  FIGS. 2 and 3 , the display substrate  100  further includes a pixel circuit layer  11  disposed between the base  10  and the first electrode layer  12 . The pixel circuit layer  11  may be used to drive the light-emitting devices described above to emit light. In some examples, the pixel circuit layer  11  includes at least switching transistors, driving transistors, and storage capacitors. 
     In some embodiments, referring to  FIGS. 1 and 2 , the side faces  1222  of the transparent conductive unit  122  are also referred to as buffer surfaces  1222 . The arrangement of the buffer surfaces  1222  may play a role of smooth transition, so that subsequent layers (e.g., the light-emitting functional layer  14 ) are not prone to breakage. It will be noted that the embodiments of the present disclosure do not limit a shape of the buffer surface  1222 , as long as the buffer surface  1222  can have the smooth transition effect on the subsequent layers and prevent the subsequent layers from being broken. 
     For example, the included angle between any side face  1222  and the flat surface  1221  of the transparent conductive unit  122  is greater than or equal to approximately 120°. Herein, “approximately” may refer to, for example, a stated value (i.e., 120°), or it may fluctuate by ten percent up and down on a basis of the stated value (i.e., 120°). That is, the included angle α may be greater than or equal to 108°; or, the included angle α may be greater than or equal to 120°; or, the included angle α may be greater than or equal to 132°. 
     In some of the above embodiments, the range of the included angle between the to buffer surface  1222  and the flat surface  1221  in the raised face is greater than or equal to approximately 120°, so that the light-emitting functional layer  14  and the second electrode layer  15  may be buffered, which may prevent the light-emitting functional layer  14  and the second electrode layer  15  from being broken. 
     It will be noted that the embodiments of the present disclosure do not limit a material of the base  10 , and the material of the base  10  may be, for example, polyimide, glass, or silicon substrate. 
     In some examples, the first electrode layer  12  is the anode layer, and the second electrode layer  15  is the cathode layer. In some other examples, the first electrode layer  12  is the cathode layer, and the second electrode layer  15  is the anode layer. 
     In some embodiments, the first electrode layer  12  is formed using a photo-etching process. On this basis, for example, chemical mechanical polishing is performed on the first electrode layer  12 , so that a thickness of a region in the transparent conductive unit  122  corresponding to the flat surface  1221  may be relatively uniform. 
     In some examples, the display substrate  100  is applied to an OLED display apparatus, and the light-emitting functional layer  14  is an organic light-emitting functional layer. In some other examples, the display substrate  100  is applied to a quantum dot light-emitting diode (QLED) display apparatus, and the light-emitting functional layer  14  is a quantum dot light-emitting functional layer. 
     In some examples, the display substrate is applied to the OLED display apparatus, and the light-emitting functional layer  14  and the second electrode layer  15  may be manufactured using an evaporation process. 
     In some other examples, the display substrate is applied to the QLED display to apparatus, the light-emitting functional layer  14  may be formed using an ink-jet printing process, and then the second electrode layer  15  may be formed using the evaporation process. 
     In some embodiments, for a light-emitting device with a top light-emitting structure, the first electrode layer  12  includes not only the transparent conductive layer  12 B, but also the reflective layer  12 A located on a side of the transparent conductive layer  12 B proximate to the base  10 , so that light emitted by the light-emitting functional layer  14  in the direction toward the first electrode layer  12  is reflected by the reflective layer  12 A. In addition, light emitted in a direction toward the second electrode layer  15  is transmitted. Herein, a material of the reflective layer  12 A is not limited, as long as the reflective layer  12 A may conduct electricity and may reflect light. 
     The material of the reflective layer  12 A may be, for example, metal. A material of the transparent conductive layer  12 B may be, for example, an oxide transparent conductive material, such as indium tin oxide (ITO). 
     It will be noted that the embodiments of the present disclosure do not limit a thickness of the transparent conductive layer  12 B. For example, referring to  FIG. 2 , the thickness dl of the transparent conductive layer  12 B is greater than 0 nm and less than or equal to approximately 200 nm. Herein, “approximately” may refer to, for example, a stated value (i.e., 200 nm), or it may also fluctuate by ten percent up and down on a basis of the stated value (i.e., 200 nm). 
     The embodiments of the present disclosure do not limit shapes of the reflective unit  121  and the transparent conductive unit  122 , for example, they may be designed according to a required light-emitting area. 
     Shapes of orthographic projections of the reflective unit  121  and the transparent conductive unit  122  on the base  10  may be same or different. 
     For example, as shown in  FIG. 1 , a shape of an orthographic projection of the reflective unit  121  on the base  10  and a shape of an orthographic projection of the transparent conductive unit  122  on the base  10  are both rectangular; or, as shown in  FIG. 4 , the shape of the orthographic projection of the reflective unit  121  on the base  10  and the shape of the orthographic projection of the transparent conductive unit  122  on the base  10  are both hexagons. 
     In some embodiments, the reflective units  121  and the transparent conductive units  122  are in one-to-one correspondence, and the transparent conductive unit  122  includes a flat surface  1221 . Therefore, the reflective units  121  and the flat surface  1221  are also in one-to-one correspondence. 
     In some embodiments, as shown in  FIG. 5 , the display substrate  100  further includes an insulating layer  13  disposed between the reflective layer  12 A and the transparent conductive layer  12 B. The insulating layer  13  has via holes  31 . The reflective unit  121  and the corresponding transparent conductive unit  122  are electrically connected through a via hole  31 . 
     A material of the insulating layer  13  may be an organic insulating material or an inorganic insulating material. In a case where the material of the insulating layer  13  is the inorganic insulating material, an effect of preventing penetration of water vapor and oxygen may be improved, so that the reflective layer  12 A may be well protected. 
     For example, the material of the insulating layer  13  is silicon oxide. 
     The embodiments of the present disclosure do not limit a size and shape of the via hole  31 , as long as the transparent conductive unit  122  may be fully electrically connected to a corresponding reflective unit  121 . 
     For example, an orthographic projection of the via hole  31  on the base  10  is a circle, and a diameter of the circle is greater than 0 nm and less than or equal to approximately 500 nm. Herein, “approximately” may refer to, for example, a stated value (i.e., 500 nm), or it may also fluctuate by ten percent up and down on a basis of the stated value (i.e., 500 nm). 
     Herein, a distance between the second electrode layer  15  and the reflective layer  12 A in the light-emitting device is a length of a microcavity thereof. In this embodiment, the insulating layer  13  is provided between the reflective layer  12 A and the transparent conductive layer  12 B. In an aspect, the length of the microcavity of the light-emitting device may be adjusted by adjusting a thickness of the insulating layer  13 , so that light may satisfy resonance conditions in the microcavity and then be strengthened, that is, a microcavity effect is generated. As a result, a microcavity resonance effect is used to improve a luminous efficiency of the light-emitting device. In another aspect, when metal materials whose chemical properties are prone to change such as aluminum are in direct contact with other conductive materials, chemical properties of the metal materials are prone to change, so that if the material of the reflective layer  12 A includes the metal materials whose chemical properties are prone to change such as aluminum, the insulating layer  13  may be used to prevent a large-area direct contact between the reflective layer  12 A and the transparent conductive layer  12 B, thereby avoiding an increase in a contact resistance of the reflective layer  12 A, a decrease in current, and affecting a display effect of the display substrate  100 . 
     On this basis, for example, as shown in  FIG. 5 , when the transparent conductive layer  12 B is manufactured, the material of each transparent conductive unit  122  passes through the via hole  31  to be in contact with a corresponding reflective unit  121 , so that to the reflective units  121  are connected to the transparent conductive units  122  in a one-to-one correspondence. 
     As another example, as shown in  FIG. 6 , the via hole  31  is filled with tungsten  32 . Since tungsten  32  has almost no effect on a contact resistance of the metal materials whose chemical properties are prone to change such as aluminum, a stable electrical connection between the reflective unit  121  and the corresponding transparent conductive unit  122  may be achieved. 
     It will be noted that the embodiments of the present disclosure do not limit the thickness of the insulating layer  13 , for example, the thickness of the insulating layer  13  may be designed according to factors such as the required length of the microcavity and insulating capacity. For example, a thickness of a portion of the insulating layer  13  located between the transparent conductive unit  122  and the corresponding reflective unit  121  is in a range from approximately 10 nm to approximately 500 nm. Herein, “approximately” may refer to, for example, a stated value (i.e., 10 nm and 500 nm), or it may also fluctuate by ten percent up and down on a basis of the stated value (i.e., 10 nm and 500 nm). 
     In the above example, since the thickness of the portion of the insulating layer  13  located between the transparent conductive unit  122  and the corresponding reflective unit  121  is set to be in the range from approximately 10 nm to approximately 500 nm, it is possible to avoid an overlarge thickness of the display substrate  100  due to an overlarge thickness of the insulating layer  13  on a basis of adjusting the length of the microcavity of the light-emitting device. 
     In some embodiments, as shown in  FIG. 7 , the reflective unit  121  includes a metal portion  1211 . 
     On this basis, for example, a material of the metal portion  1211  includes at least one of aluminum, copper, or titanium nitride. 
     For example, the material of the metal portion  1211  may only include aluminum. Aluminum has a high reflectivity to light, which may improve display brightness without changing the current. 
     Of course, the material of the metal portion  1211  may also be other metals. For example, the material of the metal portion  1211  may include copper. Since a cost of copper is relatively low, the manufacturing cost of the display substrate may be saved. As another example, the material of the metal portion  1211  may also be titanium nitride or the like. 
     In some embodiments, as shown in  FIG. 7 , the reflective unit  121  further includes a first protective portion  1212  disposed on a side of the metal portion  1211  facing away from the transparent conductive layer. In this way, the first protective portion  1212  may be used to protect the metal portion  1211  to avoid water vapor and oxygen entering the metal portion  1211  from the side of the metal portion  1211  facing away from the transparent conductive layer, thereby preventing the metal portion  1211  from being oxidized. 
     A thickness of the first protective portion  1212  may be, for example, greater than 0 nm and less than or equal to approximately 200 nm. Herein, “approximately” may refer to, for example, a stated value (i.e., 200 nm), or it may also fluctuate by ten percent up and down on a basis of the stated value (i.e., 200 nm). 
     A material of the first protective portion  1212  may be, for example, a conductive material. In this way, the first protective portion  1212  may be used to be electrically connected to the pixel circuit layer  11  on the base  10 , so that electrical signals sent by the pixel circuit layer  11  may sequentially flow through the first protective portion  1212 , the metal portion  1211 , and the transparent conductive units  122 . As a result, the display substrate  100  may achieve a light-emitting display function. It will be understood that in a case where the insulating layer  13  is provided, the electrical signals flowing from the metal portion  1211  to the transparent conductive units  122  further needs to pass through the via holes  31  (e.g., the tungsten  32  filled in the via holes  31 ) before the electrical signals flow to the transparent conductive units  122 . 
     It will be noted that the embodiments of the present disclosure do not limit a thickness and a material of the first protective portion  1212 , as long as the first protective portion  1212  may be used to protect the metal portion  1211  and prevent the metal portion  1211  from being oxidized. 
     For example, referring to  FIG. 8 , the first protective portion  1212  includes a first protective sub-portion a 1  and/or a second protective sub-portion a 2 . In a case where the first protective portion  1212  includes both the first protective sub-portion a 1  and the second protective sub-layer a 2 , the first protective sub-portion a 1  and the second protective sub-portion a 2  are stacked in a thickness direction of the base  10 . 
     A material of the first protective sub-portion a 1  includes titanium, and a material of the second protective sub-portion a 2  includes titanium nitride. 
     On this basis, for example, referring to  FIG. 9 , the second protective sub-portion a 2  in the first protective portion  1212  is closer to the metal portion  1211  than the first protective sub-portion a 1  in the first protective portion  1212 . With this arrangement, the second protective sub-portion a 2  made of titanium nitride material may be used to block mobility of metal ions (e.g., the metal materials whose chemical properties are prone to change such as aluminum) in the metal portion  1211 , and the first protective sub-portion a 1  made of titanium material may be used to improve adhesive performance between adjacent layers, thereby helping to improve stability and reliability of the display substrate  100 . 
     In some embodiments, as shown in  FIG. 10 , the reflective unit  121  further includes a second protective portion  1213  disposed on a side of the metal portion  1211  proximate to the transparent conductive layer. In this way, the second protective portion  1213  may be used to protect the metal portion  1211  to avoid water vapor and oxygen entering the metal portion  1211  from the side of the metal portion  1211  proximate to the transparent conductive layer, thereby preventing the metal portion  1211  from being oxidized. 
     A thickness of the second protective portion  1213  may be, for example, greater than 0 nm and less than or equal to approximately 200 nm. Herein, “approximately” may refer to, for example, a stated value (i.e., 200 nm) or it may also fluctuate by ten percent up and down on a basis of the stated value (i.e., 200 nm). 
     A material of the second protective portion  1213  may be, for example, a conductive material. With this arrangement, the electrical signals flowing from the metal portion  1211  to the transparent conductive units  122  may be transmitted through the second protective portion  1213 . In addition, in a case where the insulating layer  13  is provided, the electrical signals flowing from the metal portion  1211  to the transparent conductive units  122  needs to pass through the via holes  31  (e.g., the tungsten  32  filled in the via holes  31 ) after passing through the second protective portion  1213 , and then may be transmitted to the transparent conductive units  122 . 
     It will be noted that the embodiments of the present disclosure do not limit a thickness and a material of the second protective portion  1213 , as long as the second protective portion  1213  may be used to protect the metal portion  1211  and prevent the metal portion  1211  from being oxidized. 
     For example, referring to  FIG. 8 , the second protective portion  1213  includes a third protective sub-portion a 3  and a fourth protective sub-portion a 4 . In a case where the second protective portion  1213  includes both the third protective sub-portion a 3  and the fourth protective sub-portion a 4 , the third protective sub-portion a 3  and the fourth protective sub-portion a 4  are stacked in the thickness direction of the base  10 . 
     A material of the third protective sub-portion a 3  includes titanium, and a material of the fourth protective sub-portion a 4  includes titanium nitride. 
     On this basis, for example, referring to  FIG. 11 , the fourth protective sub-portion a 4  in the second protective portion  1213  is closer to the metal portion  1211  than the third protective sub-portion a 3  in the second protective portion  1213 . With this arrangement, the fourth protective sub-portion a 4  made of titanium nitride material may be used to block mobility of metal ions (e.g., the metal materials whose chemical properties are prone to change such as aluminum) in the metal portion  1211 , and the third protective sub-portion a 3  made of titanium material may be used to improve adhesive performance between adjacent layers, thereby helping to improve the stability and reliability of the display substrate  100 . 
     It will be understood that the reflective unit  121  described above may include only the second protective layer  1213 , or may include only the first protective layer  1212 , or may simultaneously include the second protective layer  1213  and the first protective layer  1212 . 
     Some embodiments of the present disclosure provide a display apparatus  200 . As shown in  FIG. 12 , the display apparatus  200  includes the display substrate  100  to described in any of the foregoing embodiments. 
     The display apparatus  200  may be used as, for example, a mobile phone, a tablet computer, a personal digital assistant (PDA), and a vehicle-mounted computer. The embodiments of the present disclosure do not specifically limit a specific use of the display apparatus  200 . 
     Beneficial effects that can be achieved by the display apparatus  200  provided by some embodiments of the present disclosure are the same as beneficial effects that can be achieved by the display substrate  100 , and will not be described herein again. 
     For example, as shown in  FIG. 12 , the display apparatus  200  may include, for example, a frame  1 , a display panel  2 , a circuit board  3 , a cover plate  4 , a camera and other electronic accessories. The display panel  2  includes the display substrate  100  and an encapsulation layer  101 . 
     In addition, the display apparatus  200  may be, for example, the OLED display apparatus, or the QLED display apparatus. 
     For example, a light exit direction of the display substrate  100  may be top-emitting, and the frame  1  may be a U-shaped frame. The display substrate  100  and the circuit board  3  are arranged in the frame  1 . The cover plate  4  is disposed on a light exit side of the display panel  2 , and the circuit board  3  is disposed on a side of the display panel  2  facing away from the cover plate  4 . 
     Some embodiments of the present disclosure provide a method of manufacturing a display substrate. Referring to  FIGS. 1, 2 and 13 , the method includes steps  1  and  2  (S 1  and S 2 ). 
     In S 1 , a base  10  is provided. 
     A material of the base  10  may be, for example, polyimide, glass, or silicon. 
     In S 2 , a first electrode layer  12  is formed on a side of the base  10 . 
     As shown in  FIG. 14 , S 2  includes steps  21  and  22  (S 21  and S 22 ). 
     In S 21 , a reflective layer  12 A is formed on the side of the base  10 , and the reflective layer  12 A includes a plurality of reflective units  121  that are spaced apart. 
     In S 22 , a transparent conductive layer  12 B is formed on a side of the reflective layer  12 A away from the base  10 , the transparent conductive layer  12 B includes a plurality of transparent conductive units  122  that are spaced apart, a transparent conductive unit  122  includes a flat surface  1221  in a middle and side faces  1222  on peripheries, and an included angle between the flat surface  1221  and a side face  1222  is an obtuse angle; the reflective units  121  and the transparent conductive units  122  are in one-to-one correspondence, and a reflective unit and a corresponding transparent conductive unit are electrically connected; and an orthographic projection of the reflective unit  121  on the base  10  is within a range of an orthographic projection of the flat surface  1221  of the corresponding transparent conductive unit  122  on the base  10 . 
     On this basis, for example, referring to  FIG. 3 , a light-emitting functional layer  14  and a second electrode layer  15  may also be sequentially formed on the base  10  on which the first electrode layer  12  is formed. 
     Through the above method, the orthographic projection of the reflective unit  12 A on the base  10  is not beyond the orthographic projection of a corresponding flat surface  1221  on the base  10 . In this way, when the light-emitting functional layer  14  emits light, light to the first electrode layer  12  in a direction perpendicular from the light-emitting functional layer  14  to the base  10  and a small amount of small-angle light in a direction toward the first electrode layer  12 , both emitted by a portion of the light-emitting functional layer  14  that overlaps an orthographic projection of the reflective layer  12 A on the base  10 , may be reflected by the reflective layer  12 A. Light emitted by a portion of the light-emitting functional layer  14  that does not overlap the reflective layer  12 A may hardly be reflected by the reflective layer  12 A. As a result, a problem of non-uniform light emission may be improved. 
     Moreover, when the light-emitting functional layer  14  emits light, large-angle light, emitted in the direction toward the first electrode layer  12  by the portion of the light-emitting functional layer  14  that overlaps the orthographic projection of the reflective layer  12 A on the base  10  may hardly be reflected by the reflective layer  12 A. Therefore, the pixel defining layer in the related art may be replaced, process steps of manufacturing the pixel defining layer may be omitted, and manufacturing process of the display substrate  100  may be simplified, which is beneficial to lower the manufacturing cost. 
     In some embodiments, as shown in  FIG. 15 , steps  211  to  213  (S 211  to S 213 ) are further provided between S 21  and S 22 . 
     In S 211 , an insulating layer  13  is formed on the base  10  on which the plurality of reflective units  121  are formed. 
     A material of the insulating layer  13  may be, for example, silicon oxide. 
     In S 212 , the insulating layer  13  is etched to form a plurality of via holes  31  exposing the plurality of reflective units  121 . 
     In S 213 , tungsten  32  is filled in the plurality of via holes  31 . For example, as shown in  FIG. 6 , tungsten  32  may be filled in the plurality of via holes  31 , so that a surface of a side of the insulating layer  13  proximate to the transparent conductive layer  12 B is flat, which facilitates subsequent production of the transparent conductive layer  12 B. 
     A material of the reflective units  121  may include metal materials whose chemical properties are prone to change such as aluminum. When the metal materials whose chemical properties are prone to change such as aluminum are in direct contact with other conductive materials, chemical properties of the metal materials are prone to change. Therefore, in a case where the material of the reflective units  121  includes the metal materials whose chemical properties are prone to change such as aluminum, the insulating layer  13  may be used to prevent a large-area direct contact between the reflective unit  121  and a corresponding transparent conductive unit  122 , thereby avoiding an increase in a contact resistance of the reflective unit  121  and a decrease in current, and affecting a display effect of the display substrate  100 . In addition, tungsten  32  is filled in the via holes  31 . Since tungsten  32  has almost no effect on a contact resistance of the metal materials whose chemical properties are prone to change such as aluminum, a stable electrical connection between the reflective unit  121  and the corresponding transparent conductive unit  122  may be achieved. 
     The foregoing descriptions are merely specific implementations of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or replacements that a person skilled in the art could conceive of within the technical scope of the present disclosure shall be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.