OLED DISPLAY PANEL

An OLED display panel includes a base substrate and an OLED device on the base substrate. The OLED device includes: an auxiliary electrode in the non-light-emitting region, the auxiliary electrode includes a conductive layer and a conductive column on a side of the conductive layer away from the base substrate, and an orthographic projection of the conductive column on the base substrate is within an orthographic projection of the conductive layer on the base substrate; and an insulating layer between the conductive layer and the base substrate; a groove is arranged on a surface of the insulating layer away from the base substrate, and an orthographic projection of the groove on the base substrate at least partially overlaps with the orthographic projection of the isolation structure on the base substrate.

TECHNICAL FIELD

The present disclosure relates to the display technology, in particular an OLED display panel.

BACKGROUND

Compared with LCD display apparatuses, OLED (organic light-emitting diode) display apparatuses have the characteristics of self-illumination, high luminous efficiency, low operating voltage, light weight, flexibility and simple manufacturing process, and are widely used in display lighting and other fields. According to a position of the light-emitting surface, OLED devices include top emitting OLED devices and bottom emitting OLED devices. Top emitting OLED devices have been widely focused studied because of their high opening ratio.

SUMMARY

The inventors noticed that top emitting OLED devices require thin cathodes and emitting anodes to increase the light transmittance. However, a surface resistance of a thin transparent cathode is large, and the IR drop is particularly obvious at the position far away from the electrode. In large size OLED display apparatuses, the cathode and the auxiliary electrode of OLED devices are usually separated by organic materials and cannot be effectively electrically connected. This results in uneven brightness of the display apparatuses.

The disclosure provides an OLED display panel. According to embodiments of the present disclosure, a contact area between a second electrode (e.g., a cathode) and an auxiliary electrode of an OLED device is increased, the bonding effect is improved, the IR drop on the second electrode is effectively reduced, and the uneven brightness of the display apparatus is eliminated.

According to an aspect of the present disclosure, an OLED display panel is provided. The OLED display panel comprises a base substrate and an OLED device on the base substrate. The OLED device comprises a light-emitting region and a non-light-emitting region; the OLED device comprises: a first electrode in the light-emitting region; an auxiliary electrode in the non-light-emitting region, the auxiliary electrode comprises a conductive layer and a conductive column on a side of the conductive layer away from the base substrate, and an orthographic projection of the conductive column on the base substrate is within an orthographic projection of the conductive layer on the base substrate; an organic light-emitting layer on a side of the first electrode away from the base substrate; a second electrode on a side of the organic light-emitting layer away from the base substrate; an isolation structure on a side of the conductive column away from the substrate, and the orthographic projection of the conductive column on the base substrate is within an orthographic projection of the isolation structure on the base substrate; and an insulating layer between the conductive layer and the base substrate; a groove is arranged on a surface of the insulating layer away from the base substrate, and an orthographic projection of the groove on the base substrate at least partially overlaps with the orthographic projection of the isolation structure on the base substrate.

Optionally, in some embodiments, the second electrode contacts a part of a top surface of the conductive layer and a part of a side surface of the conductive column.

Optionally, in some embodiments, a distance of the orthographic projection of the isolation structure on the base substrate extending beyond the orthographic projection of the conductive column on the base substrate is a, a distance between an orthographic projection of an edge of the groove on the base substrate and the orthographic projection of the conductive column on the base substrate is z, and z is less than a.

Optionally, in some embodiments, a depth of the groove is greater than a thickness of the organic light-emitting layer.

Optionally, in some embodiments, a shape of the groove is a spherical crown, and a diameter of the groove is greater than a (that is, a distance of an orthographic projection of the isolation structure on the substrate extending beyond an orthographic projection of the conductive column on the base substrate).

Optionally, in some embodiments, the diameter of the groove is greater than z (that is, a distance between an orthographic projection of an edge of the groove on the base substrate and the orthographic projection of the conductive column on the base substrate).

Optionally, in some embodiments, a shape of the groove is selected from any one of a cuboid, a spherical crown, and a connected shape of at least two spherical crowns.

Optionally, in some embodiments, a bottom surface of the isolation structure is in direct contact with a top surface of the conductive column; a material of the isolation structure comprises one of indium tin oxide and indium zinc oxide; a material of the conductive column comprises at least one of aluminum, copper, molybdenum and gold.

Optionally, in some embodiments, a material of the insulating layer is resin.

Optionally, in some embodiments, a material of the conductive layer comprises one of indium tin oxide and indium zinc oxide; a material of the second electrode comprises one of indium tin oxide and indium zinc oxide.

Optionally, in some embodiments, the conductive layer comprises a through hole, and a part of the conductive column fills the through hole.

Optionally, in some embodiments, a bottom surface of the conductive column is in direct contact with a top surface of the conductive layer.

Optionally, in some embodiments, the first electrode is connected to a thin film transistor through a via hole in the insulating layer, and a width of the groove is less than a width of the via hole in the insulating layer.

Optionally, in some embodiments, a slope angle of the groove is less than a slope angle of the via hole in the insulating layer.

Optionally, in some embodiments, the OLED display panel further comprises a pixel definition layer; an edge of the pixel definition layer extends to the groove.

Optionally, in some embodiments, a slope angle of the groove is less than a slope angle of the edge of the pixel definition layer.

Optionally, in some embodiments, a bottom vertex of the groove and the isolation structure do not overlap in the direction perpendicular to the base substrate.

Optionally, in some embodiments, the OLED display panel further comprises a gate layer and a source drain layer; wherein at least one of the gate layer and the source drain layer has a concave structure at a position corresponding to the groove.

Optionally, in some embodiments, the OLED display panel further comprises an interlayer dielectric layer; wherein the interlayer dielectric layer is provided with a concave structure at a position corresponding to the groove.

Optionally, in some embodiments, a source electrode and a drain electrode of the thin film transistor are connected with an active layer of the thin film transistor through a via hole in the interlayer dielectric layer, and a size of the via hole in the interlayer dielectric layer is larger than a size of the via hole in the insulating layer.

DETAILED DESCRIPTION OF THE DISCLOSURE

In the following, the technical solutions in the embodiments of the disclosure will be described clearly and completely in connection with the drawings in the embodiments of the disclosure. Obviously, the described embodiments are only part of the embodiments of the disclosure, and not all of the embodiments. Based on the embodiments in the disclosure, all other embodiments obtained by those of ordinary skills in the art under the premise of not paying out creative work pertain to the protection scope of the disclosure.

According to an aspect of the present disclosure, an OLED display panel is provided.FIG.1is a schematic diagram of an OLED display panel according to an embodiment of the present disclosure. The OLED display panel100comprises: a base substrate101and an OLED device102on the base substrate101; wherein the OLED device102comprises a light-emitting region103and a non-light-emitting region104; the OLED device102comprises: a first electrode105in the light-emitting region103; an auxiliary electrode in the non-light-emitting region104, the auxiliary electrode comprises a conductive layer106and a conductive column107on a side of the conductive layer106away from the base substrate101, and an orthographic projection of the conductive column107on the base substrate101is within an orthographic projection of the conductive layer106on the base substrate101; an organic light-emitting layer108on a side of the first electrode105away from the base substrate101; a second electrode109on a side of the organic light-emitting layer108away from the base substrate101; an isolation structure110on a side of the conductive column107away from the substrate101, and the orthographic projection of the conductive column107on the base substrate101is within an orthographic projection of the isolation structure110on the base substrate101; and an insulating layer111between the conductive layer106and the base substrate101; a groove112is arranged on a surface of the insulating layer111away from the base substrate101, and an orthographic projection of the groove112on the base substrate101at least partially overlaps with the orthographic projection of the isolation structure110on the base substrate101.

Those skilled in the art can understand that an array composed of multiple OLED devices may be arranged on the OLED display panel, and multiple OLED devices may have the same structure.

As shown inFIG.1, the OLED display panel100may comprise a thin film transistor TFT for driving the OLED device102. The thin film transistor TFT may comprise a gate113, an active layer114, a source115, and a drain116. The OLED display panel100may further comprise an interlayer dielectric layer ILD and a passivation layer PVX. The pixel definition layer PDL may be arranged between the light-emitting region103and the non-light-emitting region104to define the light-emitting region103. The auxiliary electrode may be connected to an external circuit via a conductor plug117. The isolation structure110may comprise a conductive material. A layer of organic light-emitting material1101and a layer of second electrode material1102may be stacked on a top of the isolation structure110in turn.

In the embodiment of the present disclosure, since the orthographic projection of the conductive column107on the base substrate101is within the orthographic projection of the isolation structure110on the base substrate101, when the organic light-emitting layer108is formed by using, for example, an evaporation process, the organic light-emitting material will be disconnected at the positon of the isolation structure110. With the isolation structure110, the part of the organic light-emitting layer108of the OLED device102extending to the non-light-emitting region104can be effectively “cut off”, thereby avoiding the transverse leakage current of the organic light-emitting layer108at this position. By arranging a groove112on the surface of the insulating layer111away from the base substrate101, the conductive layer106will also form a concave structure corresponding to the groove112, and the shape of the concave structure matches the shape of the groove112. When the organic light-emitting layer108is formed (e.g., by the evaporation process), the material of the organic light-emitting layer (i.e., the organic light-emitting material) will diffuse into the concave structure of the conductive layer106. Therefore, when the second electrode109is formed (e.g., by the sputtering process), a material of the second electrode109can be filled to a side surface of the conductive column107and the top surface of the conductive layer106through the concave structure of the conductive layer106, thereby enhancing the electrical connection between the second electrode109and the auxiliary electrode, and eliminating the uneven brightness of the display device.

Optionally, in some embodiments, the second electrode109contacts a part of the top surface of the conductive layer106and a part of the side surface of the conductive column107.

As shown inFIGS.1to3, the second electrode109contacts a part of the top surface of the conductive layer106and a part of the side surface of the conductive column107. Therefore, the contact area between the second electrode109and the auxiliary electrode of the OLED device is increased, the bonding effect is improved, and the IR drop on the second electrode109is effectively reduced, thereby further eliminating the uneven brightness of the display device.

Optionally, in some embodiments, as shown inFIGS.2and3, a distance of a the orthographic projection of the isolation structure110on the base substrate101extending beyond the orthographic projection of the conductive column107on the base substrate101is in the range of 0.5 μm to 1.3 μm; a distance z between the orthographic projection of the edge of the groove112on the base substrate101and the orthographic projection of the conductive column107on the base substrate101is less than a, and the difference between a and z is 0.2 μm to 0.4 μm; a depth d of the groove112is in the range of 200 nm to 400 nm.

FIG.2is a partial schematic diagram of the OLED display panel shown inFIG.1at the non-light-emitting region104. As described above, when the organic light-emitting layer108is formed (e.g., by the evaporation process), the material of the organic light-emitting layer diffuses into the concave structure of the conductive layer106, and the organic light-emitting layer108extending below the isolation structure110. A length of the organic light-emitting layer108extending below the isolation structure110is about 0.3 μm to 0.6 μm. The inventor finds that the difference between a and z significantly affects the electrical connection between the second electrode109and the auxiliary electrode.

In some comparison examples, when the value of a is in the range of 0.5 μm to 0.7 μm, the second electrode109only contacts the side wall of the conductive column107(not shown in the figure). In other comparison examples, when the value of a is in the range of 0.8 μm to 0.9 μm, the second electrode109contacts the side wall of the conductive column107and the top of the conductive layer106. However, the contact area between the second electrode109and the side wall of the conductive column107and the top of the conductive layer106is small (not shown in the figure), resulting in large local resistance. In other comparison examples, when the value of a is in the range of 1.0 μm to 1.3 μm, the second electrode109only contacts the top of the conductive layer106(not shown in the figure).

With the above relationship, the material of the second electrode109can be filled to the side surface of the conductive column107and the top surface of the conductive layer106through the concave structure of the conductive layer106, effectively increasing the contact area between the second electrode109and the side wall of the conductive column107and the top of the conductive layer106.

Optionally, in some embodiments, as shown inFIGS.2and3, the depth d of the groove112is greater than the thickness c of the organic light-emitting layer108, and the difference between the depth d of the groove112and the thickness c of the organic light-emitting layer108is in the range of 100 nm to 300 nm.

With the above relationship, the depth d of the groove112can be determined based on the thickness c of the organic light-emitting layer108, so as to more effectively enhance the electrical connection between the second electrode109and the auxiliary electrode.

Optionally, in some embodiments, as shown inFIGS.1,2and3, a shape of the groove112is a spherical crown, and a diameter b of the groove112is greater than a; a difference between the diameter b of the groove112and a is 0.5 μm to 1 μm. Optionally, the diameter b of the groove112is greater than z.

Optionally, in some embodiments, as shown inFIGS.4ato4c, a shape of the groove112is selected from any one of a cuboid, a spherical crown, and a connected shape of at least two spherical crowns.

The groove112may be a groove surrounding the auxiliary electrode, that is, a circular groove. Therefore, the orthographic projection of the groove112on the base substrate101may be a circle. Similarly, the groove112may also be a semicircle between the light-emitting region103and the auxiliary electrode. In alternative embodiments, a plurality of grooves112may be arranged between the light-emitting region103and the auxiliary electrode.

Optionally, in some embodiments, as shown inFIGS.1to3, the bottom surface of the isolation structure110is in direct contact with the top surface of the conductive column107; a material of the isolation structure110comprises one of indium tin oxide and indium zinc oxide; a material of the conductive column107comprises at least one of aluminum, copper, molybdenum and gold.

In order to realize the isolation structure110, in a same etching process, the etching rate of the material of the isolation structure should be less than that of the material of the conductive column. Therefore, in the present disclosure, the material of the isolation structure110are not limited to indium tin oxide or indium zinc oxide, and the material of the conductive column107are not limited to aluminum, copper, molybdenum, or gold.

Optionally, in some embodiments, a material of the insulating layer111is resin.

The groove112can be etched in the resin layer111using a mask and a lithography process. Those skilled in the art can understand that other organic insulating materials or inorganic insulating materials may also be used to form the insulating layer111.

Optionally, in some embodiments, a material of the conductive layer106comprises one of indium tin oxide (ITO) and indium zinc oxide (IZO); a material of the second electrode109comprises one of indium tin oxide and indium zinc oxide.

In the embodiments of the present disclosure, the first electrode105may be a reflective anode of the OLED device102, and the second electrode109may be a transparent cathode of the OLED device102. Therefore, the OLED device102may be a top emitting OLED device. The reflective anode may comprise a laminated structure of a conductive layer of metal oxides (indium tin oxide or indium zinc oxide) and a metal layer, such as a laminated structure of an indium tin oxide layer/a metal layer, a laminated structure of indium tin oxide layer/a metal layer/an indium tin oxide layer, and the like.

In some embodiments, the conductive layer106may be prepared simultaneously with the first electrode105. For example, the first electrode105may comprise a laminated structure of a bottom indium tin oxide layer/a metal layer/a top indium tin oxide layer.FIG.6is a flowchart of a manufacturing method of an OLED display panel according to an embodiment of the present disclosure;FIGS.7ato7cshow schematic diagrams of the structures in the manufacturing process according to the manufacturing method shown inFIG.6. A same etching process may be used to form the bottom indium tin oxide layer (1051as shown inFIG.7a) of the first electrode105and the conductive layer106; then, in another etching process, a metal layer (1052as shown inFIG.7a) of the first electrode105and the conductive column107are formed simultaneously; in another subsequent etching process, the top indium tin oxide layer (1053as shown inFIG.7a) of the first electrode105and the isolation structure110(as shown inFIG.7a) are formed simultaneously. In the above embodiment, the bottom indium tin oxide layer of the first electrode105and the conductive layer106are made of the same material (e.g., indium tin oxide); the metal layer of the first electrode105and the conductive column107are made of the same material (e.g., aluminum or copper); the top indium tin oxide layer of the first electrode105and the isolation structure110are made of the same material (e.g., indium tin oxide).

As shown inFIG.7b, by arranging a groove112on the surface of the insulating layer111away from the base substrate101, the conductive layer106will also form a concave structure corresponding to the groove112, and the shape of the concave structure matches the shape of the groove112. When the organic light-emitting layer108is formed (e.g., by the evaporation process), the material of the organic light-emitting layer108will diffuse into the concave structure of the conductive layer106.

As shown inFIG.7c, when forming the second electrode109, a connection between the second electrode109and the auxiliary electrode is formed.

Optionally, in some embodiments, as shown inFIG.2, the conductive layer106comprises a through hole, and a part of the conductive column107fills the through hole. When the thickness of the conductive layer106is relatively large, such arrangement increases the contact area between the conductive column107and the conductive layer106, thereby reducing the impedance of the auxiliary electrode.

Optionally, in some embodiments, as shown inFIG.3, the bottom surface of the conductive column107is in direct contact with the top surface of the conductive layer106.

In the embodiment shown inFIG.3, the bottom surface of the conductive column107is in direct contact with the top surface of the conductive layer106. When the thickness of the conductive layer106is relatively small, such an arrangement increases the contact area between the conductive column107and the conductive layer106, thereby reducing the impedance of the auxiliary electrode.

Optionally, in some embodiments, as shown inFIGS.1and5, the first electrode105is connected to the thin film transistor TFT through the via hole118in the insulating layer111, and a width of the groove112is less than a width of the via hole118in the insulating layer111.

In the embodiments of the present disclosure, the first electrode105is connected to the thin film transistor TFT by a via hole118in the insulating layer111. Those skilled in the art can understand that the via hole118and the groove112can be formed in the insulating layer111in the same etching process, thereby simplifying the manufacturing process of the OLED display panel.

Optionally, in some embodiments, as shown inFIGS.1and5, a slope angle of the groove112is less than a slope angle of the via hole118in the insulating layer111.

In the context of the present disclosure, “slope angle” refers to the included angle between the side wall of the groove and its top surface, or the included angle between the side wall of the via hole and its bottom surface, or the included angle between the edge of the layer and the bottom surface of the layer.

Optionally, in some embodiments, as shown inFIGS.1and5, the OLED display panel100further comprises: a pixel definition layer PDL; an edge of the pixel definition layer PDL extends to the groove112.

Optionally, in some embodiments, as shown inFIGS.1and5, the slope angle of the groove112is less than the slope angle of the edge of the pixel definition layer PDL.

In the embodiment of the present disclosure, the edge of the pixel definition layer PDL extends to the groove112. With the slope of the edge of the pixel definition layer PDL and the groove112, when the conductive layer106and the second electrode109are formed, the material of the second electrode109can be filled to the side surface of the conductive column107and the top surface of the conductive layer106through the concave structure of the conductive layer106, thereby enhancing the electrical connection between the second electrode109and the auxiliary electrode.

Optionally, in some embodiments, as shown inFIGS.1and5, a bottom vertex of the groove112and the isolation structure110do not overlap in the direction perpendicular to the base substrate101.

In the embodiments of the present disclosure, the bottom vertex of the groove112and the isolation structure110do not overlap in the direction perpendicular to the base substrate101. That is, a small part of the groove112overlaps with the isolation structure110in a direction perpendicular to the substrate101. With this structure, the conductive layer106, the organic light-emitting layer108and the second electrode109can form a desired slope at the position of the groove112, so that the material of the second electrode109can be filled to the side surface of the conductive column107and the top surface of the conductive layer106.

Optionally, in some embodiments, as shown inFIG.5, the OLED display panel100further comprises: a gate layer113′ and a source drain layer115,116; at least one of the gate layer113′ and the source drain layers115,116has a concave structure120at a position corresponding to the groove112.

In some embodiments, at least one of the gate layer113′ and the source drain layers115,116has a concave structure120at a position corresponding to the groove112. Therefore, when subsequently forming the interlayer dielectric layer ILD, passivation layer PVX, and insulation layer111, the groove112can be formed using the principle of morphology inheritance (as shown inFIG.6), thereby simplifying the process steps.

Optionally, in some embodiments, as shown inFIG.5, the OLED display panel further comprises an inter layer dielectric layer ILD; the interlayer dielectric layer ILD is provided with a concave structure121at the position corresponding to the groove112.

In some embodiments, the interlayer dielectric layer ILD is provided with a concave structure121at the position corresponding to the groove112. Therefore, when subsequently forming the passivation layer PVX and insulation layer111, the groove112can be formed using the principle of morphology inheritance (as shown inFIG.5), thus simplifying the process steps. In addition, with the above structure, the concave structure121and the via hole119in the interlayer dielectric layer ILD may also be formed in the same etching process.

Optionally, in some embodiments, as shown inFIG.5, the source115and drain116of the thin film transistor TFT are connected with the active layer114of the thin film transistor TFT through a via hole119in the interlayer dielectric layer ILD. A size of the via hole119in the interlayer dielectric layer ILD is larger than that of the via hole118in the insulating layer111.

In the subsequent manufacturing process, the planarization layer PVX will be applied on the interlayer dielectric layer ILD. With the above structure, a groove on the planarization layer PVX can be easily formed (as shown inFIG.5).

According to another aspect of the present disclosure, a manufacturing method of an OLED display panel is provided.FIG.6is a flowchart of a manufacturing method of an OLED display panel according to an embodiment of the present disclosure;FIGS.7ato7cshow schematic diagrams of the structures in the manufacturing process according to the manufacturing method shown inFIG.6. The method comprises the following steps: S101: providing a base substrate101, and S102: arranging an OLED device102on the base substrate101, the OLED device102comprising a light-emitting region103and a non-light-emitting region104. The step of arranging the OLED device102on the base substrate101(S102) comprises: S1021: forming a first electrode105in the light-emitting region103(as shown inFIG.7a); S1022: forming an auxiliary electrode in the non-light-emitting region104, the auxiliary electrode comprising a conductive layer106and a conductive column107on a side of the conductive layer106away from the base substrate101, an orthographic projection of the conductive column107on the base substrate101being within an orthographic projection of the conductive layer106on the base substrate101(as shown inFIG.7a); S1023: forming an organic light-emitting layer108(as shown inFIG.7b) on a side of the first electrode105away from the base substrate101by an evaporation process; and S1024: forming a second electrode109on a side of the organic light-emitting layer108away from the base substrate101by a sputtering process, the second electrode109contacting a part of a top surface of the conductive layer106and a part of a side surface of the conductive column107(as shown inFIG.7c).

In the embodiment of the present disclosure, since the orthographic projection of the conductive column107on the base substrate101is within the orthographic projection of the isolation structure110on the base substrate101, when the organic light-emitting layer108is formed by using, for example, an evaporation process, the organic light-emitting material will be disconnected at the position of the isolation structure110. With the isolation structure110, the part of the organic light-emitting layer108of the OLED device102extending to the non-light-emitting region104can be effectively “cut off”, thereby avoiding the transverse leakage current of the organic light-emitting layer108at this position. By arranging a groove112on the surface of the insulating layer111away from to the base substrate101, the conductive layer106will also form a concave structure corresponding to the groove112, and the shape of the concave structure matches the shape of the groove112. When the organic light-emitting layer108is formed (e.g., by the evaporation process), the material of the organic light-emitting layer (i.e., the organic light-emitting material) will diffuse into the concave structure of the conductive layer106. Therefore, when the second electrode109is formed (e.g., by the sputtering process), a material of the second electrode109can be filled to a side surface of the conductive column107and the top surface of the conductive layer106through the concave structure of the conductive layer106, thereby enhancing the electrical connection between the second electrode109and the auxiliary electrode, and eliminating the uneven brightness of the display device.

Those skilled in the art can understand that an array composed of multiple OLED devices can be arranged on the OLED display panel, and multiple OLED devices can have the same structure.

In the description of the disclosure, the terms such as “on” and “below” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the disclosure rather than requiring the disclosure to be constructed and operated in a specific orientation, so it cannot be understood as a limitation of the disclosure.

In the description of the present specification, the description referring to the terms “an embodiment”, “some embodiments”, “an example”, “a specific example”, or “some examples” or the like means a specific feature, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic expression of the above terms does not necessarily have to refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in any one or more of the embodiments or examples. In addition, those skilled in the art can combine the different embodiments or examples described in this specification and features of different embodiments or examples without conflicting with each other. In addition, it should be noted that the terms “first” and “second” are used for descriptive purposes only, and are not to be construed as indicating or implying relative importance or implicitly indicating the number of indicated technical features.

The above embodiments are only used for explanations rather than limitations to the present disclosure, the ordinary skilled person in the related technical field, in the case of not departing from the spirit and scope of the present disclosure, may also make various modifications and variations, therefore, all the equivalent solutions also belong to the scope of the present disclosure, the patent protection scope of the present disclosure should be defined by the claims.