CN109216407B

CN109216407B - OLED display panel and preparation method thereof

Info

Publication number: CN109216407B
Application number: CN201710526518.2A
Authority: CN
Inventors: 敖伟; 高峰; 王明晖; 姜海峰; 王岩; 彭兆基
Original assignee: Kunshan Govisionox Optoelectronics Co Ltd
Current assignee: Kunshan Govisionox Optoelectronics Co Ltd
Priority date: 2017-06-30
Filing date: 2017-06-30
Publication date: 2022-08-26
Anticipated expiration: 2037-06-30
Also published as: CN109216407A

Abstract

The invention provides an OLED display panel and a preparation method thereof. At least part of the pixel definition layer is provided with a boss, the film packaging layer comprises a first film packaging layer, a second film packaging layer and a third film packaging layer, the first film packaging layer and the third film packaging layer are inorganic film layers, the second film packaging layer is an organic film layer, the third film packaging layer which is the inorganic film layer above the boss is in contact with the first film packaging layer, the shearing resistance of the OLED display panel can be improved, and the separation or position deviation between the film packaging layer and the cathode and between the film layers in the functional layer is reduced or avoided.

Description

OLED display panel and preparation method thereof

Technical Field

The invention relates to the technical field of display, in particular to an OLED display panel and a preparation method thereof.

Background

In recent years, organic electroluminescent displays have received increasing attention as a new flat panel display. The core component of an organic electroluminescent display is an organic electroluminescent device (OLED, also called an organic light emitting diode). The OLED light-emitting principle is that under the drive of a certain voltage, electrons and holes are respectively injected into an electron transport layer and a hole transport layer from a cathode and an anode, the electrons and the holes respectively migrate to a light-emitting layer through the electron transport layer and the hole transport layer and meet in the light-emitting layer to form excitons, so that light-emitting molecules are excited, and visible light is emitted through radiation relaxation.

The OLED display panel has the characteristics of lightness, thinness, wide visual angle, low power consumption, high response speed, capability of realizing flexible display and the like. Since it is an active light emitting type device, it is considered to have great advantages in displaying high definition high speed video, and is developing toward practical use in recent years. However, since the light emitting layer of the OLED display panel, which functions to emit light, is sensitive to external environmental factors such as moisture and oxygen, if the OLED display panel is exposed to moisture or oxygen, the performance of the device may be drastically reduced or completely damaged. In order to improve the lifetime of OLEDs and the stability of the devices, good encapsulation is required to exclude ambient moisture and oxygen.

Conventional glass cover plates or metal cover plate packages have achieved good results but are not fully suitable for some important or potential applications such as top-emitting OLED display technology, flexible OLED display technology or flexible OPVs. Therefore, a film packaging technology is developed in the industry, and one or more layers of films are adopted to block water and oxygen, so that the emergent or incident path of light is not blocked, and the flexibility of the substrate is not influenced. However, the inventor researches and discovers that the adhesion between the film packaging layer and the cathode is weak, and particularly in the bending process of the flexible display panel, the phenomena of curling and cracking even occur between the film packaging layer and the cathode and between film layers in the functional layer, so that the capability of blocking water and oxygen is reduced, the performance of the light emitting layer is influenced, and the service life and the performance of the OLED display panel are further influenced.

Disclosure of Invention

The invention aims to solve the problem that separation or position deviation occurs between a thin film packaging layer and a cathode and between film layers in a functional layer in an OLED display panel.

In order to solve the above problems, in one aspect, an OLED display panel is provided, which includes a substrate, and a bottom electrode, a pixel defining layer, a functional layer, a top electrode, and a thin film encapsulation layer formed on the substrate; the pixel definition layer is provided with a plurality of pixel openings, and a bottom electrode, a functional layer and a top electrode which are positioned in the pixel openings form a pixel unit; the OLED display panel further comprises a boss formed on at least part of the pixel defining layer, the film packaging layer comprises a first film packaging layer, a second film packaging layer and a third film packaging layer, the first film packaging layer and the third film packaging layer are inorganic film layers, the second film packaging layer is an organic film layer, and the third film packaging layer above the boss is in contact with the first film packaging layer.

Optionally, a cross-sectional width of an end of the boss close to the pixel defining layer is smaller than a cross-sectional width of an end of the boss far from the pixel defining layer, a recess is formed between the pixel defining layer and the boss, and the thin film encapsulation layer fills the recess.

Optionally, the cross section of the boss perpendicular to the substrate surface and parallel to the width direction of the pixel definition layer is in an inverted trapezoid shape.

Optionally, the cross-sectional width of the pixel definition layer at an end close to the substrate is greater than the cross-sectional width at an end far from the substrate.

Optionally, a boss opening is further formed in the boss, and the boss opening at least partially penetrates through the boss.

Optionally, the OLED display panel further includes a planarization layer formed on the substrate, and the bottom electrode is formed on the planarization layer; the boss opening further penetrates through a portion of the thickness or the entire thickness of the pixel defining layer, or the boss opening further penetrates through the entire thickness of the pixel defining layer and a portion of the thickness or the entire thickness of the planarization layer.

Optionally, each pixel unit is formed with one or more of the bosses.

Optionally, the material of the boss is the same as that of the pixel defining layer.

Optionally, the total thickness of the pixel defining layer and the mesa is between 2 μm and 8 μm.

In another aspect, a method for manufacturing an OLED display panel is provided, including: providing a substrate; and forming a bottom electrode, a pixel definition layer, a functional layer, a top electrode and a film packaging layer on the substrate, wherein the pixel definition layer is provided with a plurality of pixel openings, a plurality of bosses are also formed on the OLED display panel, the film packaging layer comprises a first film packaging layer, a second film packaging layer and a third film packaging layer, the first film packaging layer and the third film packaging layer are inorganic film layers, the second film packaging layer is an organic film layer, and the third film packaging layer above the bosses is in contact with the first film packaging layer.

Compared with the prior art, the invention has the advantages that the bosses are arranged on at least part of the pixel defining layer, the film packaging layer comprises the first film packaging layer, the second film packaging layer and the third film packaging layer, the first film packaging layer and the third film packaging layer are inorganic film layers, the second film packaging layer is an organic film layer, the third film packaging layer which is the inorganic film layer and is arranged above the bosses is contacted with the first film packaging layer, the shearing resistance of the OLED display panel can be improved, and the separation or position offset between the film packaging layer and the cathode and between the film layers in the functional layer can be reduced or avoided.

Drawings

FIG. 1 is a schematic cross-sectional view illustrating an OLED display panel according to an embodiment of the present invention;

FIGS. 2a to 2f are schematic cross-sectional views illustrating a manufacturing process of the OLED display panel shown in FIG. 1;

FIG. 3 is a schematic cross-sectional view of an OLED display panel according to a second embodiment of the present invention;

FIGS. 4a to 4b are schematic cross-sectional views illustrating the OLED display panel shown in FIG. 3 during a manufacturing process;

FIG. 5 is a schematic cross-sectional view of an OLED display panel according to a third embodiment of the present invention;

FIGS. 6 a-6 b are schematic cross-sectional views illustrating a manufacturing process of the OLED display panel shown in FIG. 5;

FIG. 7 is a schematic cross-sectional view illustrating an OLED display panel according to a fourth embodiment of the present invention;

FIGS. 8a 8b are schematic cross-sectional views illustrating a manufacturing process of the OLED display panel shown in FIG. 7;

FIG. 9 is a schematic cross-sectional view of an OLED display panel according to a fifth embodiment of the present invention;

FIGS. 10 a-10 b are schematic cross-sectional views illustrating the OLED display panel shown in FIG. 9 during a manufacturing process;

fig. 11 is a schematic top view illustrating an OLED display panel according to a fifth embodiment of the invention;

FIG. 12 is a schematic top view of another OLED display panel according to a fifth embodiment of the present invention;

FIG. 13 is a schematic cross-sectional view of another OLED display panel in accordance with a fifth embodiment of the present invention;

FIG. 14 is a schematic cross-sectional view of another OLED display panel according to a fifth embodiment of the present invention;

FIG. 15 is a schematic view of the distribution of dimples in a sixth embodiment of the present invention;

FIG. 16 is a schematic view of laser drilling according to a sixth embodiment of the present invention;

FIG. 17 is a schematic cross-sectional view of an OLED display panel according to a seventh embodiment of the present invention;

FIGS. 18 a-18 b are schematic cross-sectional views illustrating a manufacturing process of the OLED display panel shown in FIG. 17;

FIG. 19 is a schematic cross-sectional view of an OLED display panel according to an eighth embodiment of the present invention;

FIGS. 20 a-20 b are schematic cross-sectional views illustrating a manufacturing process of the OLED display panel shown in FIG. 19;

FIG. 21 is a schematic view of a bank of an OLED display panel according to a ninth embodiment of the present invention;

reference numerals in the drawings indicate:

100-a substrate; 110-bottom electrode; 120-pixel definition layer; 120' -well; 130-pixel openings; 140-a functional layer; 150-a top electrode; 160-thin film encapsulation layer; 161-a first thin film encapsulation layer; 162-a second thin film encapsulation layer; 163-third thin film encapsulation layer; 164-a fourth thin film encapsulation layer; 165-fifth thin film encapsulation layer; 166-a sixth thin film encapsulation layer; 167-a seventh thin film encapsulation layer; 168-eighth thin film encapsulation layer; 170-concave; 170a, 170 b-side walls of the recess; 170 c-bottom wall of recess; 180-boss; 191-a first dike; 192-a second dam; 200-a hard mask layer; 200' -a patterned hard mask layer; 210-patterned photoresist layer.

Detailed Description

In the background art, it has been mentioned that the functional layer in the OLED display panel is very sensitive to external environmental factors such as moisture and oxygen, and if the functional layer in the OLED display panel is directly exposed to the moisture and oxygen, the performance of the OLED display panel may be drastically reduced or completely damaged. Therefore, the encapsulation is very important for the OLED device, and the multilayer Thin Film Encapsulation (TFE) technology has a good development prospect as a novel OLED encapsulation method. However, the inventor researches and finds that, due to poor adhesion of the thin film encapsulation layer and the underlying top electrode, especially in a flexible display panel, under the alternating action of tensile stress and compressive stress, separation or position shift of the thin film encapsulation layer and the underlying film layers and separation or position shift between the film layers inside the OLED functional layer occur, thereby causing premature failure of the encapsulation and shortening the service life of the display device.

Based on the above research, an embodiment of the present invention provides an OLED display panel, which includes a substrate, and a bottom electrode, a pixel defining layer, a functional layer, a top electrode, and a thin film encapsulation layer formed on the substrate. The pixel definition layer is formed with a plurality of pixel openings, and the bottom electrodes, the functional layer and the top electrodes positioned in the pixel openings form a plurality of pixel units. The OLED display panel further comprises a boss formed on at least part of the pixel definition layer, the film packaging layer comprises a first film packaging layer, a second film packaging layer and a third film packaging layer, the first film packaging layer and the third film packaging layer are inorganic film layers, the second film packaging layer is an organic film layer, the third film packaging layer above the boss is in contact with the first film packaging layer, the shearing resistance of the OLED display panel can be improved, and separation or position deviation between the film packaging layer and the cathode and between the film layers inside the functional layer is reduced or avoided.

The cross section width of one end of the boss close to the pixel defining layer is smaller than that of one end of the boss far away from the pixel defining layer, a recess is formed between the pixel defining layer and the boss, and the thin film packaging layer fills the recess. Furthermore, the cross section of the boss, which is perpendicular to the surface of the substrate and parallel to the width direction of the pixel defining layer, is in an inverted trapezoid shape.

The cross-sectional width of one end of the pixel defining layer close to the substrate is larger than that of one end of the pixel defining layer far away from the substrate.

Wherein, still be formed with the boss opening in the boss, the boss opening at least part is run through the boss. Further, the OLED display panel also comprises a planarization layer formed on the substrate, and the bottom electrode is formed on the planarization layer; the boss opening may also extend through a portion or all of the thickness of the pixel definition layer, or the boss opening may also extend through the entire thickness of the pixel definition layer and a portion or all of the thickness of the planarization layer.

Wherein, each pixel unit is provided with one or more bosses.

The material of the boss and the material of the pixel defining layer can be the same or different.

Wherein the total thickness of the pixel defining layer and the boss is between 2 μm and 8 μm.

The embodiment of the invention also provides a preparation method of the OLED display panel, which comprises the following steps:

providing a substrate; and

the substrate is provided with a bottom electrode, a pixel definition layer, a functional layer, a top electrode and a thin film packaging layer, wherein the pixel definition layer is provided with a plurality of pixel openings, a plurality of bosses are further formed at the pixel definition layer, the thin film packaging layer comprises a first thin film packaging layer, a second thin film packaging layer and a third thin film packaging layer, the first thin film packaging layer and the third thin film packaging layer are inorganic film layers, the second thin film packaging layer is an organic film layer, and the third thin film packaging layer above the bosses is in contact with the first thin film packaging layer.

The OLED display panel, the packaging method thereof, and the OLED display device according to the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. Advantages and features of the present invention will become apparent from the following description and from the claims.

It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention. Wherein the thickness of layers, films, panels, regions are exaggerated for clarity. In order to more clearly explain the present invention, parts not related to the explanation are omitted from the drawings, and the same reference numerals denote the same parts throughout.

It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.

Example one

Fig. 1 is a schematic cross-sectional view of an OLED display panel in this embodiment. As shown in fig. 1, the OLED display panel includes a substrate 100, and a bottom electrode 110 (an anode in this embodiment), a pixel defining layer 120, a functional layer 140, a top electrode 150 (a cathode in this embodiment), and a thin film encapsulation layer 160 formed on the substrate 100.

The substrate material of the substrate 100 may be quartz, glass, metal, resin, etc., wherein the resin substrate includes, but is not limited to, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyethylene naphthalate (PBN), and polycarbonate resin. For flexible display devices, flexible substrates, such as Polyimide (PI) substrates, are preferred. In addition, the substrate 100 preferably has good barrier properties against water and gas, and for bottom emission devices, the substrate should also have good transparency, i.e., light in the visible wavelength range can pass through the substrate.

The bottom electrode 110 is formed on the substrate 100, for example, as anodes of the red, green, and blue pixel units, respectively. The bottom electrode material composition may include a simple substance or an alloy of a metal element such as chromium (Cr), gold (Au), platinum (Pt), nickel (Ni), copper (Cu), tungsten (W), aluminum (Al), and silver (Ag). The selected metal elements may be from the list above, but are not limited to the above ranges. The bottom electrode 110 may also be formed of a transparent conductive oxide thin film, for example, a transparent conductive thin film composed of Indium Tin Oxide (ITO), indium zinc oxide (InZnO), zinc oxide (ZnO).

The pixel defining layer 120 serves to define the shape and size of a light emitting region (pixel region). In this embodiment, the pixel defining layer 120 has a single-layer structure and is made of Polyimide (PI). In a specific implementation, the pixel defining layer 120 may also be a stacked structure, for example, when a functional layer is prepared by a solution method, the pixel defining layer 120 preferably includes two separating layers, each separating layer is prepared by an organic material, for example, the separating layer is composed of a layer of lyophilic material and a layer of lyophobic organic material, and the lyophobic organic material is located on an upper layer.

The pixel defining layer 120 is provided with a pixel opening 130 corresponding to a light emitting region. The OLED display panel includes an emitting region and a non-emitting region, the pixel opening 130 of the pixel defining layer 120 is used to define the emitting region and the non-emitting region, a region corresponding to the pixel opening 130 is the emitting region, and a region outside the pixel opening 130 is the non-emitting region. The pixel definition layer 120 is typically a grid-like structure. The functional layer 140 and the top electrode 150 may be disposed not only in the pixel opening 130 but also above the pixel defining layer 120, and only a portion corresponding to the pixel opening 130 emits light to form a light emitting region. Preferably, the cross-sectional width (aperture) of the pixel defining layer 120 at the end (bottom end) close to the substrate 100 is larger than the cross-sectional width at the end (top end) far from the substrate 100, so as to ensure that the subsequently formed top electrode 150 continuously covers the sidewall of the pixel defining layer 120, i.e. ensure the continuity of the cathode. In this embodiment, a cross section (a longitudinal section) of the pixel defining layer 120 perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer is an isosceles trapezoid, and preferably, the longitudinal section of the pixel defining layer 120 is an isosceles trapezoid. It is understood that, in the specific implementation, the longitudinal section of the pixel defining layer 120 may have other shapes, for example, the longitudinal section of the pixel defining layer 120 may have a slope shape other than a regular trapezoid, and the included angle between the sidewall and the bottom wall of the pixel defining layer 120 is, for example, between 30 to 80 degrees, so as to avoid that the evaporation of the top electrode is affected by an excessively large slope, and to avoid that the pixel defining layer occupies an excessively large area by an excessively small slope.

The functional layer 140 may have a multi-layer structure, and in addition to a light emitting layer necessary for ensuring normal light emitting display of the organic light emitting display panel, based on the consideration of product cost, light emitting brightness and light emitting efficiency, other film layers may be optionally disposed by those skilled in the art according to actual product requirements, for example, an electron transport layer and a hole transport layer for balancing electrons and holes, and an electron injection layer and a hole injection layer for enhancing injection of electrons and holes are further included. In general, a red pixel unit, a green pixel unit, and a blue pixel unit are mainly formed on the substrate 100, and each pixel unit includes a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer, which are sequentially stacked on the substrate 100. The light emitting layer is disposed in the pixel opening 130, and other film layers (the hole injection layer, the hole transport layer, the electron transport layer, and the electron injection layer) may be selectively patterned, or alternatively, the entire film layer may be prepared without performing a patterning process, so as to save mask cost and simplify process flow.

The hole injection layer is used for improving the injection capability of holes and has the function of modifying the surface of the bottom electrode (anode) to play a role of a buffer layer. The hole injection layer may have a thickness of 5nm to 100nm, and preferably a thickness of 8nm to 50 nm. The thickness of the hole transport layer depends on the overall structure of the device, but is preferably from 10nm to 200nm, more preferably from 15nm to 150 nm. Examples of the polymer material constituting the hole transport layer include organic solvent-soluble light-emitting materials such as polyvinylcarbazoles and derivatives thereof, polyfluorenes and derivatives thereof, polyanilines and derivatives thereof, polysilanes and derivatives thereof, polyoxosilane derivatives having an arylamine structure in a main chain or a side chain, polythiophenes and derivatives thereof, polypyrroles and derivatives thereof, and the like. The hole transport layer may be taken from the above range, but is not limited thereto. The light emitting layer is a region where holes and electrons are recombined under the action of an electric field to generate excitons and emit light. The thickness of the light-emitting layer depends on the overall performance requirements of the device, but is preferably from 10nm to 200nm, more preferably from 15nm to 100 nm. The materials for forming the red light emitting layer, the green light emitting layer and the blue light emitting layer can be small molecule materials or high molecule materials. For small molecule systemsThe light-emitting layer can be prepared by either evaporation or solution methods, in which small molecules are generally used as guests, for example, doped in a polymer host to emit light. Polymers are generally prepared by solution processes due to their intrinsic properties. Examples of the light-emitting polymer include polyfluorenes and derivatives thereof, poly-p-phenylenevinylene derivatives, polyphenylene derivatives, polyvinylcarbazole derivatives, polythiol derivatives; examples of the small molecule light emitting material include perylene pigments, coumarin pigments, rhodamine pigments, fluorescein pigments, diene or polyene derivatives, and the like. In addition, a material obtained by doping an organic electroluminescent material in the aforementioned polymer, for example, a material obtained by doping rubrene, perylene, tetraphenylbutadiene, nile red, and coumarin is also within such a luminescent material. It should be understood that the above is only given as an example of the luminescent material, but the selection range is not limited to the above range, and can be selected from the existing disclosed or commercialized material range. The electron transport layer serves to improve electron transport efficiency of the light emitting unit. The electron transport layer preferably also has the ability to block holes. The electron transport layer in this embodiment is disposed above the red light emitting layer, the green light emitting layer, and the blue light emitting layer as a common layer to be deposited. Examples of the material constituting the electron transport layer include, but are not limited to, quinoline, perylene, phenanthroline, bisstyrene, pyrimidine, triazole, oxazole, fullerene, oxadiazole, and fluorenone, or their derivatives or metal complexes. The electron injection layer is provided between the electron transport layer and the cathode for improving the efficiency of electron injection from the cathode. Examples of the electron injection layer constituent material include oxides of lithium (Li) ₂ O), fluoride of Lithium (LiF), and composite oxide of cesium (Cs) ₂ CO ₃ ) And mixtures of oxides/complex oxides. The material of the electron injection layer is not limited to the foregoing materials. The constituent material of the electron injection layer also includes alkaline earth metals such as calcium and barium, alkali metals such as lithium and cesium, and oxides/composite oxides/fluorides of metals having a low work function (such as indium and magnesium) as the above metal elements. It should be understood that the above is only given as an example of a functional layer, but thatThe range of choice is not limited to the above examples and can be selected from the range of existing published or commercialized materials.

The top electrode 150 is made of a conductive thin film and may have a thickness of 5nm to 1000nm, preferably 10nm to 150 nm. The top electrode material includes aluminum (Al), magnesium (Mg), calcium (Ca), sodium (Na), gold (Au), silver (Ag), copper (Cu), chromium (Cr), platinum (Pt), nickel (Ni), and alloys thereof. The top electrode 150 may also be formed of a thin film made of a simple substance or an alloy or an oxide of the aforementioned metal elements, such as Indium Tin Oxide (ITO), indium zinc oxide (InZnO), zinc oxide (ZnO) conductive thin film.

The thin film encapsulation layer 160 is located above the top electrodes of the red pixel unit, the green pixel unit and the blue pixel unit, and the thin film encapsulation layer 160 may be one or more layers, and the material used may be an organic film layer or an inorganic film layer, or a stacked structure of an organic film layer and an inorganic film layer. The thickness of the thin film encapsulation layer 160 is preferably between 200nm and 20 μm, and can be adjusted according to the material and process for preparing the thin film encapsulation layer and the actual requirement. The top surface (the surface far from the substrate 100) of the thin film encapsulation layer 160 may be flat (as shown in fig. 1), but of course, the top surface of the thin film encapsulation layer 160 may also be sloped, and the flatness of the top surface of the thin film encapsulation layer may be adjusted by adjusting the thickness of the organic film layer.

The inventor researches and discovers that the advantages of the organic material for preparing the thin film packaging layer are mainly as follows: 1. the flatness is good, the flatness can be realized (the depression existing on the substrate is filled), and the subsequent growth of an inorganic film layer by a method such as Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD) or Atomic Layer Deposition (ALD) is facilitated; 2. organic materials with larger thickness can be prepared by the existing process; 3. the organic material has better bending resistance. However, organic materials are inferior to inorganic materials in water oxygen barrier properties. The organic material commonly used in the OLED display panel manufacturing process is mainly polymethyl methacrylate (PMMA), which is commonly called acrylic or organic glass. The organic materials in the thin film encapsulation layer are typically prepared using flash evaporation and inkjet printing processes. The main advantage of inorganic material is that the water-oxygen barrier property is betterThe organic material is good, but the bending resistance of the organic material is poor, and an inorganic film layer with larger thickness is not easy to prepare in the actual process. The inorganic materials preferably used in the thin film package are: silicon oxide (SiO) ₂ ) Silicon nitride (SiN), aluminum oxide (Al) ₂ O ₃ ) Titanium oxide (TiO) ₂ ). Among them, silicon nitride and aluminum oxide are superior to silicon oxide and titanium oxide in refractive index (denseness), and thus silicon nitride and aluminum oxide are superior to silicon oxide and titanium oxide in water-oxygen barrier property. However, the silicon oxide has better bonding force with other films and better bending resistance. Based on the above research, the thin film package preferably adopts a combination of an organic material and an inorganic material, for example, a stacked structure of an inorganic material/an organic material/an inorganic material, and specifically, the following combination may be adopted: silicon nitride/organic material/silicon nitride; alumina + silicon nitride/organic material/silicon nitride + alumina; silicon oxide + silicon nitride/organic material/silicon nitride + silicon oxide. Of course, several inorganic material layers may be stacked, for example, alumina + titania/alumina + titania, i.e. the combination is composed of four layers of alumina and titania, which has a good water and oxygen barrier effect, and at the same time, each inorganic material layer has a small thickness, and thus, the flexible display device can still be applied.

The inventor also finds that, although the film encapsulation layer 160 can isolate the surrounding water vapor and oxygen, and prevent the functional layer 140 from being exposed to the environment with water vapor or oxygen, the adhesion between the film encapsulation layer 160 and the functional layer 140 is weak, especially when the OLED display panel needs to be bent frequently, separation or displacement between the film encapsulation layer 160 and the top electrode 150 and between organic film layers inside the functional layer 140 is easy to occur, and the shear resistance of the OLED display panel is poor, resulting in the reduction of the water and oxygen barrier ability. Based on this, in the present embodiment, a recess 170 is formed through the pixel defining layer 120 (refer to fig. 2e and fig. 2f for emphasis), the recess 170 is formed in the pixel defining layer 120, and may penetrate through the pixel defining layer 120 to expose a film layer (such as a planarization layer) below the pixel defining layer 120, may penetrate through only a portion of the thickness of the pixel defining layer 120, may penetrate through the pixel defining layer 120 and then extend downward through a portion of the thickness of the planarization layer, may penetrate through the pixel defining layer 120 and then extend downward through the entire thickness of the planarization layer to expose a film layer (such as a passivation layer) below the planarization layer, and the depth of the recess 170 may be adjusted accordingly according to actual needs. In addition, if the pixel definition layer is below corresponding to an inactive area in the product, the recess 170 may even continue to extend downward as long as the OLED display function is not affected. In addition, the present invention does not limit the width of the recess (the dimension in the direction parallel to the substrate), and the width of the recess can be appropriately adjusted on the premise that the recess does not affect the original function of the pixel defining layer.

In the present embodiment, as shown in fig. 2e and 2f, the recess 170 is a vertical hole, i.e. the

side walls

170a, 170b of the recess 170 are perpendicular to the bottom wall 170c of the recess 170. It has been found that the use of vertical holes can reduce or prevent the adhesion of the functional layer 140 and the top electrode 150 to the sidewalls 170a, 170b, i.e., the functional layer 140 and the top electrode 150 mainly cover the bottom wall of the recess 170, but not cover or reduce the coverage of the sidewalls of the recess 170, so that the encapsulation film layer 160 subsequently filled in the recess 170 can be directly bonded to the sidewalls of the recess 170, and the adhesion is better, and the shear resistance is better in this structure.

It will be appreciated that in actual production, some deviation is allowed between the actual shape (and size) and the design shape (and size) of the various products. Generally, the use requirements can be met as long as the actual shape (and size) of the product is within the allowable deviation range of the design shape (and size). For example, the side wall of the recess 170 may be a straight wall, and the straight wall forms an angle of 90 degrees or close to 90 degrees with the bottom wall; the side wall of the recess 170 may also be an arc-shaped wall having some curvature, and when the side wall is an arc-shaped wall, the included angle between the tangent line and the bottom wall is 90 degrees or close to 90 degrees.

In addition, in this embodiment, in all regions of the OLED display panel, recesses are formed in the pixel defining layer corresponding to each pixel unit, and the recesses are annularly distributed and surround each pixel unit. It should be appreciated that it is not necessary to form the recesses in the pixel definition layers in all regions of the substrate 100, for example, for a foldable flexible display panel, the recesses may be formed only in the pixel definition layer at the folding position, and since the folding probability of the region is large, and the film encapsulation layer and the cathode at the folding position and the film layers inside the functional layer are more easily separated from each other than the region with less folding probability, the recesses are preferably formed in the pixel definition layer at this region. In yet another aspect, the depressions in each region may be all the same size and shape, may be all the same shape but not all the same size, or may be all different shapes and sizes. In fact, as long as the recess is formed, so that the subsequent encapsulation film is filled into the recess to form the anchoring structure, the shear resistance of the OLED display panel can be improved.

The following describes the manufacturing process of the above OLED display panel in detail with reference to fig. 1 and fig. 2a to 2 f.

First, referring to fig. 2a, a substrate 100 is provided, and a known driving circuit may be formed on the substrate 100, wherein a drain electrode of a driving transistor of the driving circuit is electrically connected to a bottom electrode 110 of the OLED through a via hole. The specific structure and forming method of the driving circuit are well known in the art and will not be described in detail here. A passivation layer may be further formed on the substrate 100 to protect the driving circuit on the substrate. The passivation layer is preferably an inorganic material such as silicon nitride, silicon oxide, aluminum oxide, etc., but it should be understood that the above is only an example of the passivation layer, but the selection range is not limited to the above example and can be selected from the existing published or commercialized material range.

Next, as shown in fig. 2a, a conductive film is formed on the substrate 100 and patterned, the conductive film in the pixel region (light-emitting region) is remained, and a plurality of bottom electrodes 110 are formed, wherein the plurality of bottom electrodes 110 are respectively connected to the drain electrodes of the driving transistors of different pixel units. It will be appreciated that for bottom emitting devices the bottom electrode is preferably made of a transparent conductive film such as ITO, whereas for top emitting devices the bottom electrode need not be made of a transparent conductive film. Preferably, before forming the bottom electrode 110, a polymer film is formed on the bottom electrode 110 by, for example, spin coating, thereby forming a planarization layer.

Next, as shown in fig. 2a, a polymer film is prepared on the bottom electrode 110 by, for example, spin coating, and a pixel defining layer 120 is formed in a corresponding patterning manner according to the properties of the polymer, wherein the pixel defining layer 120 is provided with a pixel opening 130 corresponding to a light emitting region. Specifically, the polymer film may be patterned by a method of exposure development (when the polymer is a photosensitive polymer) or by a method of exposure development and dry etching (when the polymer is a non-photosensitive polymer), thereby forming the plurality of pixel openings 130. The pixel defining layer 120 may have a single-layer structure or a stacked structure in which a plurality of spacer layers are stacked. For the composition process of the pixel defining layer formed by laminating a plurality of separating layers, the composition process can be optimized to adopt one-time composition process after all the pixel defining layer films are formed, such as an exposure development process and/or a dry etching process, thereby saving more cost. In this embodiment, the pixel definition layer 120 adopts a grid-shaped (lattice-shaped) structure, and the pixel openings 130 defined by the pixel definition layer 120 are, for example, square openings.

Next, forming the recess 170 in the pixel defining layer 120 may specifically include the following steps:

referring to fig. 2b, a hard mask layer (hard mask) 200 is formed on the bottom electrode 110 and the pixel defining layer 120 by a method such as Chemical Vapor Deposition (CVD) or Physical Vapor Deposition (PVD). The hard mask layer 200 is preferably an inorganic material because the inorganic material has a high etch selectivity with respect to the organic material forming the pixel defining layer 120, which may facilitate patterning of the pixel defining layer 120 to form the recess 170 therein. Specifically, the material of the hard mask layer 200 is, for example, silicon nitride, silicon oxide, aluminum oxide, etc., but it should be understood that the above is only an example of the hard mask layer, but the selection range is not limited to the above example, and the hard mask layer may be selected from the range of the existing published or commercialized materials, and may be any hard mask layer as long as the hard mask layer has a high etching selectivity with respect to the material of the pixel defining layer so that a recess may be formed.

Referring to fig. 2c, a photoresist layer is prepared on the hard mask layer 200 by, for example, spin coating, and patterned by exposure and development, the patterned photoresist layer 210 covers a partial region of the top surface and a full region of the side surface of the hard mask layer 200, has a photoresist opening at a position where a recess is to be formed, and exposes the hard mask layer 200 not covered by the pixel defining layer;

referring to fig. 2d, the hard mask layer 200 is etched using the patterned photoresist layer 210 as a mask, so as to form a patterned hard mask layer 200 ', where the patterned hard mask layer 200' covers a partial region of the top surface and a full region of the side surface of the pixel defining layer 120, and has a hard mask layer opening at a position where a recess is to be formed.

Referring to fig. 2e, the pixel defining layer 120 is etched using the patterned photoresist layer 210 and the patterned hard mask layer 200' as a mask, thereby forming the recess 170. In the process of etching the pixel defining layer 120, the patterned photoresist layer 210 is simultaneously consumed, so that the step of removing the photoresist can be omitted, and the remaining photoresist can also be removed by plasma ashing or the like. The etching process is, for example, a dry etching process, and specific etching process parameters may be adaptively adjusted according to the depth of a recess to be formed, and details are not described herein. In this embodiment, the recess 170 penetrates through the pixel defining layer 120 to expose a layer below the pixel defining layer 120. In practical implementation, the recess 170 may also be a portion of the pixel defining layer 120, and does not expose a layer below the pixel defining layer 120. Alternatively, the recess 170 may be a planarization layer that extends through the pixel definition layer 120 and then extends downward through a portion of the thickness, or may extend through the pixel definition layer 120 and then extends downward through the entire planarization layer to expose a film layer (such as a passivation layer) below the planarization layer.

In the above description, the pixel defining layer 120 is formed first, and then the recess 170 is formed in the pixel defining layer 120, because the pixel defining layer 120 has a different shape from the recess 170 in this embodiment, the pixel defining layer 120 has a regular trapezoid structure (with a slope), the recess 170 is a vertical through hole (the side wall of the recess is perpendicular to the bottom wall of the recess), and the difficulty of forming the two shapes in one patterning process is high, so a multiple patterning process is selected. However, it should be appreciated that if the pixel defining layer 120 and the recesses 170 have the same or nearly the same topography, such as both regular trapezoid structures or both vertical structures, a single patterning process, such as an exposure and development process and/or a dry etching process, may be used, which may save mask costs and simplify the process flow.

Referring to fig. 2f, after the recess 170 is formed in the pixel defining layer 120, the functional layer 140 and the top electrode 150 are sequentially formed. At the pixel opening 130, the functional layer 140 covers the bottom electrode 110, the top electrode 150 covers the functional layer 140, and the bottom electrode 110, the functional layer 140, and the top electrode 150, which are sequentially stacked at the pixel opening, form a pixel unit. At the pixel defining layer 120, the functional layer 140 covers the patterned hard mask layer 200' on the pixel defining layer 120 and the bottom of the recess 170, and the cathode 150 covers the functional layer 140. Since the recess 170 is a vertical through hole in the present embodiment, the functional layer 140 and the top electrode 150 are not easily attached to the sidewall of the recess 170, which is beneficial for the subsequently formed planarization layer to contact the sidewall of the pixel defining layer 120, thereby improving the adhesion.

The functional layer 140 includes, for example, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer. The functional layer may be formed in the regions partitioned by the aforementioned pixel defining layer 120 or formed on all the regions together. Specifically, a solution or other dispersion system containing a material forming the hole injection layer, such as polyaniline, polythiophene, or the like, is sprayed on the exposed surface of the bottom electrode 110, for example, by an inkjet method. Then, the hole injection layer is formed by heat treatment (drying treatment) in which the atmosphere and temperature are determined according to the characteristics of the hole injection material used. The hole transport layer is prepared on the hole injection layer described above in a manner similar to the hole injection layer. The red light emitting layer and the green light emitting layer are prepared on the hole transport layer by a coating method. And then removing the organic solvent by means of heat treatment to obtain a uniform thin film. The blue light emitting layer is fabricated according to the material or device structure used. For the polymer light emitting material, a solution method such as coating is generally used to prepare a thin film. For the small-molecule blue light-emitting material, a thin film is generally deposited by evaporation, and may be located only in the blue light-emitting pixel unit, or may be located as a common layer above the entire hole transport layers of the red light-emitting layer, the green light-emitting layer, and the blue light-emitting pixel unit, depending on the requirements of the device structure. After the light emitting layer is formed, an electron transport layer, an electron injection layer, and a top electrode made of the foregoing materials may be formed over the entire area by evaporation. The light-emitting layer is disposed in the pixel opening 130 to form a pixel unit only at the pixel opening, and other film layers (the hole injection layer, the hole transport layer, the electron transport layer, and the electron injection layer) may be selectively patterned, or a film layer on the whole surface may be prepared without performing a patterning process, so as to save the mask cost and simplify the process flow. For simplicity, the functional layer is schematically shown as a continuous film, but it is understood that the functional layer may be a laminate structure, and at least the light-emitting layer therein is patterned.

After the top electrode 150 is formed, as shown in fig. 1, a thin film encapsulation layer 160 is formed by a method such as an evaporation method or an inkjet printing method. Since the recess 170 is formed in the pixel defining layer 120, the thin film encapsulation layer 160 fills the recess 170 and covers the top electrode 150, and thus, the thin film encapsulation layer 160 filled in the recess 170 forms a plurality of anchoring structures, which effectively enhances the shear resistance of the OLED display panel and prevents the thin film encapsulation layer and the top electrode and the functional layer from being separated.

Specifically, the film encapsulation layer 160 includes four layers, which are a first film encapsulation layer 161 and a second film encapsulation layer 161 respectivelyTwo thin film encapsulation layers 162, a third thin film encapsulation layer 163, and a fourth thin film encapsulation layer 164. Specifically, a first thin film encapsulation layer 161 fills the recess 170 and covers the top electrode 150, and a second thin film encapsulation layer 162, a third thin film encapsulation layer 163, and a fourth thin film encapsulation layer 164 are sequentially stacked on the first thin film encapsulation layer 161. The second thin film encapsulation layer 162 and the fourth thin film encapsulation layer 164 may be silicon oxide (SiO) ₂ ) Silicon nitride (SiN), aluminum oxide (Al) ₂ O ₃ ) Titanium oxide (TiO) ₂ ) Any one or a combination of more of them. The thickness of each layer in the film encapsulation layer 160 can be adjusted according to the requirement, which is not limited by the invention.

In summary, in the embodiment, the recess is formed in the pixel defining layer, the recess at least penetrates through a part of the thickness of the pixel defining layer, the first film encapsulating layer in the film encapsulating layer fills the recess to form the anchoring structure, and the anchoring structure is adopted to effectively enhance the adhesion between the film encapsulating layer and the top electrode, improve the anti-shearing force of the OLED display panel, and reduce or avoid the separation or position offset phenomenon between the film encapsulating layer and the cathode and between the film layers in the functional layer. Furthermore, the recess is a vertical hole, which is beneficial for the contact between the first thin film encapsulation layer prepared by organic materials and the pixel defining layer, and the adhesion between the organic materials is better.

Example two

Fig. 3 is a schematic cross-sectional view of an OLED display panel according to a second embodiment of the invention. As shown in fig. 3, the OLED display panel includes a substrate 100, and a bottom electrode 110 (an anode in this embodiment), a pixel defining layer 120, a functional layer 140, a top electrode 150 (a cathode in this embodiment), and a thin film encapsulation layer 160 formed on the substrate 100.

As shown in fig. 4a and 4b, the pixel defining layer 120 is provided with a pixel opening 130 corresponding to a light emitting region. The OLED display panel includes a light emitting region and a non-light emitting region, the pixel opening 130 of the pixel defining layer 120 is used to define the light emitting region and the non-light emitting region, a region corresponding to the pixel opening 130 is the light emitting region, and regions except the pixel opening 130 are the non-light emitting regions. The functional layer 140 and the top electrode 150 may be disposed not only in the pixel opening 130 but also above the pixel defining layer 120, and only a portion corresponding to the pixel opening 130 emits light to form a light emitting region. Preferably, the cross-sectional width of the pixel defining layer 120 at one end (bottom end) close to the substrate 100 is larger than that at one end (top end) far from the substrate 100, so as to ensure that the subsequently formed top electrode 150 continuously covers the sidewall of the pixel defining layer 120, i.e. ensure the continuity of the cathode. Specifically, in the present embodiment, a cross section (longitudinal section) of the pixel defining layer 120 perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer is an isosceles trapezoid, and preferably, the longitudinal section of the pixel defining layer 120 is an isosceles trapezoid. It is understood that in an implementation, the longitudinal section of the pixel defining layer 120 may have other shapes, for example, the longitudinal section of the pixel defining layer 120 may have a slope shape other than a regular trapezoid, and the included angle between the sidewall and the bottom wall of the pixel defining layer 120 may be between 30 and 80 degrees.

In this embodiment, the cross-sectional width of the recess 170 at the end (bottom end) close to the substrate 100 is larger than the cross-sectional width at the end (top end) far from the substrate 100. Specifically, the cross section (longitudinal section) of the recess 170 perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer is an isosceles trapezoid, and preferably, the longitudinal section of the recess 170 is an isosceles trapezoid. It is understood that in the implementation, the longitudinal section of the recess 170 may have other shapes, for example, the longitudinal section of the recess 170 may have a slope shape other than a regular trapezoid, and the included angle between the side wall and the bottom wall of the recess 170 may be between 30 and 80 degrees. Research shows that the anchoring structure formed by the depressions with narrow upper parts and wide lower parts has better shear resistance. In addition, in actual production, a certain deviation is allowed between the actual shape (and size) and the designed shape (and size) of each product. In general, the use requirements can be met as long as the actual shape (and size) of the product is within the allowable deviation range of the designed shape (and size). For example, the side wall of the recess may be a straight wall, and the included angle between the straight wall and the bottom wall is less than 90 degrees, such as between 30 and 80 degrees; the side wall of the recess can also be an arc-shaped wall with some radians, and when the side wall is the arc-shaped wall, the included angle between the tangent line of the arc-shaped wall and the bottom wall is less than 90 degrees, such as between 30 and 80 degrees.

In this embodiment, the recess 170 penetrates the pixel defining layer 120 to expose a film layer (such as a planarization layer) under the pixel defining layer 120, as shown in fig. 4 a. In a specific embodiment, the recess 170 may also be the pixel defining layer 120 that only penetrates a part of the thickness, it may also be a planarization layer that penetrates the pixel defining layer 120 and then extends downward through a part of the thickness, and it may further extend downward through the pixel defining layer 120 and then extends downward through the entire thickness so as to expose a film layer (such as a passivation layer) below the planarization layer, and the depth of the recess 170 may be adjusted accordingly according to actual needs. In addition, if the pixel definition layer is below corresponding to an inactive area in the product, the recess 170 may even continue to extend downward as long as the OLED display function is not affected. Moreover, the present invention does not limit the width (dimension in the direction parallel to the substrate) of the recess, and the width of the recess can be properly adjusted on the premise that the recess does not affect the original function of the pixel definition layer.

In this embodiment, a recess is formed in the pixel definition layer corresponding to each pixel unit, and one recess is formed in each pixel definition layer. It should be appreciated that it is not necessary to form a recess in the pixel definition layer in all regions of the substrate 100, for example, in the case of a foldable flexible display panel, a recess may be formed only in the pixel definition layer at the folding portion, and since the folding probability of the region is large, the separation between the film encapsulation layer and the cathode at the folding portion and between the film layers inside the functional layer is easier to occur compared to the region with less folding, so that it is preferable to form a recess in the pixel definition layer at this region. On the other hand, the size and shape of the depressions of the respective regions may or may not be completely the same. In fact, as long as the recess is formed, so that the subsequent encapsulation film is filled into the recess to form the anchoring structure, the shear resistance of the OLED display panel can be improved.

The following describes a manufacturing process of the above OLED display panel with reference to fig. 4a to 4 b.

First, as shown in fig. 4a, a substrate 100 is provided, a conductive film is formed on the substrate 100, and the conductive film is patterned to form a plurality of bottom electrodes 110, wherein the plurality of bottom electrodes 110 are respectively connected to drain electrodes of driving transistors of different pixel units.

Next, as shown in fig. 4a, a polymer film is prepared on the bottom electrode 110 by a method such as spin coating, and a pixel defining layer 120 is formed in a corresponding patterning manner according to the properties of the polymer, the pixel defining layer 120 is provided with a pixel opening 130 corresponding to a light emitting region, and a recess 170 is formed in the pixel defining layer 120. The cross-sectional width of the pixel defining layer 120 at the end close to the substrate 100 is greater than the cross-sectional width at the end far from the substrate 100, and correspondingly, the cross-sectional width of the pixel opening 130 at the end close to the substrate 140 is less than the cross-sectional width at the end far from the substrate 100, that is, the pixel opening 130 has a structure with a wide top and a narrow bottom. The cross-sectional width of the end of the recess 170 close to the substrate 100 is greater than the cross-sectional width of the end of the recess 170 far from the substrate 100, that is, the recess 170 has a structure with a narrow top and a wide bottom.

The pixel opening 130 and the recess 170 may be formed by a double exposure and development process using the same negative photoresist as a mask. In the first exposure, a relatively small exposure amount may be selected to control the formation of the pixel defining layer 120 with a narrow top and a wide bottom and the pixel opening 130 with a wide top and a narrow bottom; in the second exposure, a relatively large exposure amount may be selected to control the formation of the recess 170 having a narrow top and a wide bottom. It should be understood that, in practice, the formation order of the pixel opening 130 and the recess 170 can be adjusted, for example, in the first exposure, a relatively large exposure can be selected, so as to control the formation of the recess 170 with a narrow top and a wide bottom; in the second exposure, a relatively small exposure amount may be selected to control the formation of the pixel defining layer 120 with a narrow top and a wide bottom and the formation of the pixel opening 130 with a wide top and a narrow bottom. In this embodiment, the relatively large exposure dose selected for the first exposure is, for example, greater than 300mJ/cm ² The second exposure is selected to a relatively small exposure, e.g., less than 30mJ/cm ² . It should be understood that the following description,the "relatively large exposure amount" used in the first exposure is a large amount of exposure amount relative to the exposure amount used in the second exposure, and similarly, the "relatively small exposure amount" used in the second exposure is a small amount of exposure amount relative to the exposure amount used in the first exposure, and is not limited to a specific numerical value. In practice, one skilled in the art can select the exposure amount values specifically adopted by the two-time exposure process through a limited number of experiments according to the above disclosure and the selected pixel definition layer material and the exposure machine, so as to control the shapes of the pixel opening 130 and the recess 170, which is not specifically limited herein.

After forming the recess, sequentially forming the functional layer 140 and the top electrode 150 by, for example, evaporation or inkjet printing, and forming the thin film encapsulation layer 160 by, for example, CVD, wherein the thin film encapsulation layer 160 adopts, for example, a stacked structure of inorganic material/organic material/inorganic material, specifically, several combinations of the following may be adopted: silicon nitride/organic material/silicon nitride; alumina + silicon nitride/organic material/silicon nitride + alumina; silicon oxide + silicon nitride/organic material/silicon nitride + silicon oxide.

In summary, in the embodiment, the recess is formed in the pixel defining layer, the recess at least penetrates through a part of the thickness of the pixel defining layer, the first film encapsulating layer in the film encapsulating layer fills the recess to form the anchoring structure, and the anchoring structure is adopted to effectively enhance the adhesion between the film encapsulating layer and the top electrode, improve the anti-shearing force of the OLED display panel, and reduce or avoid the separation or position offset phenomenon between the film encapsulating layer and the cathode and between the film layers in the functional layer. Further, the recess is a hole with a narrow top and a wide bottom, so that the anchoring structure formed by the recess has better shearing resistance.

EXAMPLE III

Fig. 5 is a schematic cross-sectional view of the OLED display panel in this embodiment. As shown in fig. 5, the OLED display panel includes a substrate 100, and a bottom electrode 110 (an anode in this embodiment), a pixel defining layer 120, a functional layer 140, a top electrode 150 (a cathode in this embodiment), and a thin film encapsulation layer 160 formed on the substrate 100.

As shown in fig. 6a and 6b, the pixel defining layer 120 is provided with a pixel opening 130 corresponding to a light emitting region. The OLED display panel includes a light emitting region and a non-light emitting region, the pixel opening 130 of the pixel defining layer 120 is used to define the light emitting region and the non-light emitting region, a region corresponding to the pixel opening 130 is the light emitting region, and regions except the pixel opening 130 are the non-light emitting regions. The functional layer 140 and the top electrode 150 may be disposed not only in the pixel opening 130 but also above the pixel defining layer 120, and only a portion corresponding to the pixel opening 130 emits light to form a light emitting region. Preferably, the cross-sectional width of the pixel defining layer 120 at one end (bottom end) close to the substrate 100 is larger than that at one end (top end) far from the substrate 100, so as to ensure that the subsequently formed top electrode 150 continuously covers the sidewall of the pixel defining layer 120, i.e. ensure the continuity of the cathode. Specifically, in the present embodiment, a cross section (longitudinal section) of the pixel defining layer 120 perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer is an isosceles trapezoid, and preferably, the longitudinal section of the pixel defining layer 120 is an isosceles trapezoid. It is understood that in an implementation, the longitudinal section of the pixel defining layer 120 may have other shapes, for example, the longitudinal section of the pixel defining layer 120 may have a slope shape other than a regular trapezoid, and the included angle between the sidewall and the bottom wall of the pixel defining layer 120 may be between 30 and 80 degrees.

In this embodiment, the film encapsulation layer 160 includes three layers, which are a first film encapsulation layer 161, a second film encapsulation layer 162 and a third film encapsulation layer 163. Specifically, a first thin film encapsulation layer 161 covers the top electrode 150, and a second thin film encapsulation layer 162 and a third thin film encapsulation layer 163 are sequentially stacked on the first thin film encapsulation layer 161. The first thin film encapsulation layer 161 and the third thin film encapsulation layer 163 are inorganic film layers, and silicon oxide (SiO) may be used ₂ ) Silicon nitride (SiN), aluminum oxide (Al) ₂ O ₃ ) Titanium oxide (TiO) ₂ ) For example by CVD, PVD or ALD. The second thin film encapsulation layer 162 is an organic film layer, and may be made ofPMMA is made, for example, by means of ink-jet printing. The thickness of each layer in the film encapsulation layer 160 can be adjusted according to the requirement, which is not limited by the invention.

Referring to fig. 6a and 6b, in the present embodiment, the recess 170 is located above the pixel defining layer 120 and penetrates through the first encapsulating thin film layer 161, the top electrode 150 and the functional layer 140, so as to expose a top portion of the pixel defining layer 120, and thus, the second encapsulating thin film layer 162 made of an organic material may fill the recess 170 to contact the pixel defining layer 120, thereby improving the adhesion of the thin film encapsulating layer. In one embodiment, after the recess 170 penetrates through the first encapsulating film 161, the top electrode 150 and the functional layer 140, it may also extend downward through a part of the thickness of the pixel defining layer 120, it may also extend down through the full thickness of the pixel definition layer 120 to expose a layer (such as a planarization layer) below the pixel definition layer 120, may also extend down through a portion of the thickness after extending through the full thickness of the pixel definition layer 120, may further extend down through the full thickness of the pixel definition layer 120 to expose a layer (such as a passivation layer) below the planarization layer, and, in addition, if the pixel definition layer below corresponds to an inactive area in the product, the recess 170 may even continue to extend downwards as long as the OLED display function is not affected, and in any case the depth of the recess 170 may be adjusted accordingly according to actual needs. In addition, the present invention does not limit the width (dimension in the direction parallel to the substrate) of the recess, and the width of the recess can be appropriately adjusted on the premise that the recess does not affect the original function of the pixel defining layer.

In this embodiment, the cross-sectional width of the end (bottom end) of the recess 170 close to the substrate 100 is smaller than the cross-sectional width of the end (top end) of the recess 170 far from the substrate 100, specifically, the cross-section (longitudinal cross-section) of the recess 170 perpendicular to the substrate surface and parallel to the width direction of the pixel definition layer is an inverted trapezoid, preferably, the longitudinal cross-section of the recess 170 is an isosceles trapezoid. It is understood that in the implementation, the longitudinal cross section of the recess 170 may have other shapes, for example, the longitudinal cross section of the recess 170 may have a cross sectional width near one end (bottom end) of the substrate 100 larger than that at an end (top end) away from the substrate 100, and the cross section of the recess 170 perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer has a regular trapezoid shape. It is understood that in actual production, a certain deviation is allowed between the actual shape (and size) and the designed shape (and size) of each product. Generally, the use requirements can be met as long as the actual shape (and size) of the product is within the allowable deviation range of the designed shape (and size). For example, the side wall of the recess may be a straight wall, and the included angle between the straight wall and the bottom wall is less than 90 degrees, for example, between 30 and 80 degrees; the side wall of the recess can also be an arc wall with a certain radian, and when the side wall is the arc wall, the included angle between the tangent line of the arc wall and the bottom wall is less than 90 degrees, such as between 30 and 80 degrees.

In this embodiment, a recess is formed in each pixel defining layer corresponding to each pixel unit, and a plurality of recesses are formed in each pixel defining layer. It should be appreciated that a recess may be formed in each pixel defining layer. In fact, it is not necessary to form the recesses in all regions of the substrate 100, for example, in the case of a foldable flexible display panel, the recesses may be formed only in the pixel definition layer at the folding portion, and since the probability of bending is high in the region, and the film encapsulation layer and the cathode at the folding portion and the film layers inside the functional layer are more easily separated from each other than in the region with less bending, the recesses are preferably formed in the pixel definition layer in this region. On the other hand, the size and shape of the recess of each region may or may not be completely the same. In practice, as long as the recess is formed, so that the subsequent encapsulation film is filled into the recess to form the anchoring structure, the shear resistance of the OLED display panel can be improved.

The following describes a manufacturing process of the above OLED display panel with reference to fig. 6a to 6 b.

First, as shown in fig. 6a, a substrate 100 is provided, a conductive film is formed on the substrate 100, and the conductive film is patterned to form a plurality of bottom electrodes 110, wherein the plurality of bottom electrodes 110 are respectively connected to drain electrodes of driving transistors of different pixel units.

Next, as shown in fig. 6a, a polymer film is formed on the bottom electrode 110 by, for example, spin coating, and a pixel defining layer 120 is formed in a corresponding patterning manner according to the properties of the polymer, wherein the pixel defining layer 120 is provided with a pixel opening 130 corresponding to a light emitting region. Specifically, the polymer film may be patterned by exposure development (when the polymer is a photosensitive polymer) or by exposure development and dry etching (when the polymer is a non-photosensitive polymer), thereby forming the plurality of pixel openings 130.

Next, the functional layer 140 and the top electrode 150 are sequentially formed by a method such as evaporation or inkjet printing, and the first thin film encapsulation layer 161 is formed by a method such as CVD. The first thin film encapsulation layer 161 is an inorganic film layer, and may be made of silicon oxide (SiO) ₂ ) Silicon nitride (SiN), aluminum oxide (Al) ₂ O ₃ ) Titanium oxide (TiO) ₂ ) Any one or a combination of more of them.

Next, the first thin film encapsulation layer 161, the top electrode 150, and the functional layer 140 are etched to form a recess 170 exposing the pixel defining layer 120.

Subsequently, a second thin film encapsulation layer 162 and a third thin film encapsulation layer 163 are formed. The third thin film encapsulation layer 162 is also an inorganic film layer, and may be made of silicon oxide (SiO) ₂ ) Silicon nitride (SiN), aluminum oxide (Al) ₂ O ₃ ) Titanium oxide (TiO) ₂ ) Any one or a combination of more of them. The second encapsulation film layer 162 is an organic film layer, and may fill the recess 170 and contact the pixel defining layer 120. Since the second encapsulation thin film layer 162 and the pixel defining layer 120 are both organic materials, the adhesion between the two layers is good, and the adhesion of the thin film insulating layer can be improved.

In summary, in the embodiment, the recess is formed above the pixel defining layer, and the recess penetrates through the first thin film encapsulation layer, the top electrode and the functional layer, and the recess is filled with the second thin film encapsulation layer made of an organic material to form the anchoring structure.

Example four

Fig. 7 is a schematic cross-sectional view of an OLED display panel according to a fourth embodiment of the invention. As shown in fig. 7, the OLED display panel includes a substrate 100, and a bottom electrode 110 (an anode in this embodiment), a pixel defining layer 120, a functional layer 140, a top electrode 150 (a cathode in this embodiment), and a thin film encapsulation layer 160 formed on the substrate 100.

As shown in fig. 8a and 8b, the pixel defining layer 120 is provided with a pixel opening 130 corresponding to a light emitting region. The OLED display panel includes an emitting region and a non-emitting region, the pixel opening 130 of the pixel defining layer 120 is used to define the emitting region and the non-emitting region, a region corresponding to the pixel opening 130 is the emitting region, and regions except the pixel opening 130 are the non-emitting regions. The functional layer 140 and the top electrode 150 may be disposed not only in the pixel opening 130 but also above the pixel defining layer 120, and only a portion corresponding to the pixel opening 130 emits light to form a light emitting region. Preferably, the cross-sectional width of the pixel defining layer 120 at one end (bottom end) close to the substrate 100 is larger than that at one end (top end) far from the substrate 100, so as to ensure that the subsequently formed top electrode 150 continuously covers the sidewall of the pixel defining layer 120, i.e. ensure the continuity of the cathode. Specifically, in the present embodiment, a cross section (longitudinal section) of the pixel defining layer 120 perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer is an isosceles trapezoid, and preferably, the longitudinal section of the pixel defining layer 120 is an isosceles trapezoid. It is understood that in an implementation, the longitudinal section of the pixel defining layer 120 may have other shapes, for example, the longitudinal section of the pixel defining layer 120 may have a slope shape other than a regular trapezoid, and the included angle between the sidewall and the bottom wall of the pixel defining layer 120 may be between 30 and 80 degrees.

It has been found that in order to ensure the bending property of the flexible panel, it is desirable that the thickness of the thin film encapsulation layer is as thin as possible, but it is desirable that the thickness is as thin as possible in the pixel region (light emitting region)The inorganic film layer in the film packaging layer is thicker to ensure the effect of blocking water and oxygen. Meanwhile, it is also desirable that the inorganic film layer in the thin film encapsulation layer can be in contact with the pixel defining layer to improve the adhesion capability of the thin film encapsulation layer. Based on these analyses, in the present embodiment, the thin film encapsulation layer 160 includes a first thin film encapsulation layer 161 and a second thin film encapsulation layer 162, both of which are inorganic film layers, and silicon oxide (SiO) may be used ₂ ) Silicon nitride (SiN), aluminum oxide (Al) ₂ O ₃ ) Titanium oxide (TiO) ₂ ) Any one or a combination of more of them. Specifically, a first thin film encapsulation layer 161 is formed first, then a recess 170 penetrating through the first encapsulation thin film layer 161, the top electrode 150 and the functional layer 140 is formed above the pixel definition layer 120, and then a second thin film encapsulation layer 162 is formed, wherein the second thin film encapsulation layer 162 covers the first encapsulation thin film layer 161 and fills the recess 170. Thus, the first film encapsulation layer 161 and the second film encapsulation layer 162 are formed at the pixel opening, and the first film encapsulation layer 161 above the pixel defining layer 120 is formed with a recess, so that the first film encapsulation layer 161 corresponding to a partial region above the pixel defining layer 120 is excavated, and only the second film encapsulation layer 162 reduces the thickness of the inorganic film layer in a partial region above the pixel defining layer 120. In addition, the second thin film encapsulation layer 162 contacts the pixel defining layer 120 through the recess 170, so that the contact area between the second thin film encapsulation layer 162 and the pixel defining layer 120 is increased, although the adhesion between the inorganic material and the pixel defining layer is not as good as the adhesion between the organic material and the pixel defining layer, the adhesion between the second thin film encapsulation layer 162 and the pixel defining layer 120 is better than the adhesion between the second thin film encapsulation layer 162 and the top electrode 150, so that the adhesion of the thin film encapsulation layer can be improved, and the anchoring structure itself also helps to improve the anti-shearing force of the device.

In this embodiment, the first thin film encapsulation layer 161 and the second thin film encapsulation layer 162 are both inorganic film layers, and in fact, the conventional once deposited inorganic film layer is formed in two times, that is, the total thickness of the first thin film encapsulation layer 161 and the second thin film encapsulation layer 162 is the same as the thickness of the conventional once deposited inorganic film layer, for example, 0.5 μm to 1.5 μm. Specifically, the thickness of the first film encapsulation layer 161 is greater than or equal to the thickness of the second film encapsulation layer 162, for example, the thickness ratio of the first film encapsulation layer 161 to the second film encapsulation layer 162 may be 1:1 to 10:1, so that the arrangement is to give consideration to both the water and oxygen blocking performance and the bending performance, on one hand, the thickness of the first film encapsulation layer 161 is not too thin to avoid damaging the functional layer when the recess is formed by etching, and on the other hand, the thickness of the second film encapsulation layer 162 is set to be smaller than the thickness of the first film encapsulation layer 161, so that the thickness of the second film encapsulation layer 162 retained in the recess 170 subsequently is relatively thin, and the bending effect can be achieved well. Practice shows that the thickness of the first film encapsulation layer 161 and the second film encapsulation layer 162 is 1:1 (i.e. the thickness of the first film encapsulation layer and the second film encapsulation layer are equal), the water and oxygen barrier property and the bending property can be better considered.

In this embodiment, the cross-sectional width of the end (bottom end) of the recess 170 close to the substrate 100 is smaller than the cross-sectional width of the end (top end) of the recess 170 far from the substrate 100, specifically, the cross-section (longitudinal section) of the recess 170 perpendicular to the substrate surface and parallel to the width direction of the pixel definition layer is an inverted trapezoid, preferably, the longitudinal section of the recess 170 is an isosceles trapezoid. It is understood that in the implementation, the longitudinal cross section of the recess 170 may have other shapes, for example, the longitudinal cross section of the recess 170 may have a cross sectional width near one end (bottom end) of the substrate 100 larger than that at an end (top end) away from the substrate 100, and the cross section of the recess 170 perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer has a regular trapezoid shape. It will be appreciated that in actual production, there is a certain deviation allowable between the actual shape (and size) and the design shape (and size) of each product. Generally, the use requirements can be met as long as the actual shape (and size) of the product is within the allowable deviation range of the design shape (and size). For example, the side wall of the recess may be a straight wall, and the included angle between the straight wall and the bottom wall is less than 90 degrees, for example, between 30 and 80 degrees; the side wall of the recess can also be an arc wall with a certain radian, and when the side wall is the arc wall, the included angle between the tangent line of the arc wall and the bottom wall is less than 90 degrees, such as between 30 and 80 degrees.

In this embodiment, the cross-sectional shape (parallel to the substrate surface) of the recess 170 may be a circle, an ellipse, or a polygon, such as a triangle, a rectangle, a diamond, etc., which is not limited by the invention.

In this embodiment, a recess is formed in each pixel defining layer corresponding to each pixel unit, and a plurality of recesses are formed in each pixel defining layer. In a specific implementation, a recess may be formed on each pixel defining layer. Furthermore, it is not necessary to form the recesses in all regions of the substrate 100, for example, in the case of a foldable flexible display panel, the recesses may be formed only in the pixel defining layer at the folding portion, and since the probability of bending is high in the region, and the separation or displacement between the thin film encapsulation layer and the cathode and between the film layers inside the functional layer is more likely to occur in the region where the folding portion is not bent, the recesses are preferably formed in the pixel defining layer in the region. On the other hand, the size and shape of the depressions of the respective regions may or may not be completely the same. In fact, the shear resistance of the OLED can be improved as long as the recess is formed so that the subsequent encapsulation film is filled into the recess to form the anchoring structure.

The following briefly describes the manufacturing process of the above OLED display panel with reference to fig. 8a to 8 b.

First, as shown in fig. 8a, a substrate 100 is provided, a conductive thin film is formed on the substrate 100, and the conductive thin film is patterned to form a plurality of bottom electrodes 110, wherein the plurality of bottom electrodes 110 are respectively connected to drain electrodes of driving transistors of different pixel units.

Next, as shown in fig. 8a, a polymer film is formed on the bottom electrode 110 by, for example, spin coating, and a pixel defining layer 120 is formed in a corresponding patterning manner according to the properties of the polymer, wherein the pixel defining layer 120 is provided with a pixel opening 130 corresponding to a light emitting region. Specifically, the polymer film may be patterned by exposure development (when the polymer is a photosensitive polymer) or by exposure development and dry etching (when the polymer is a non-photosensitive polymer), thereby forming the plurality of pixel openings 130.

Next, as shown in fig. 8b, the first thin film encapsulation layer 161, the top electrode 150 and the functional layer 140 are etched to form a recess 170 exposing the pixel defining layer 120. Specifically, a patterned protective layer is formed over the first thin film encapsulation layer 161 by, for example, an inkjet printing process, the patterned protective layer protects the region where the recess 170 is not to be formed, and the first thin film encapsulation layer 161, the top electrode 150, and the functional layer 140 over the pixel defining layer 120 are etched by, for example, dry etching to form the recess 170. Subsequently, the protective layer formed by inkjet printing may be removed, and a second thin film encapsulation layer 162 is formed, as shown in fig. 7. Of course, the protective layer may not be removed, but the second film encapsulation layer 162 is directly formed on the protective layer, so as to achieve the purpose of improving the bending performance without losing the water and oxygen blocking capability.

In the specific implementation, a photoresist layer may be formed over the first thin film encapsulation layer 161 by spin coating, and then a patterned photoresist layer is formed by performing an exposure and development process, where the patterned photoresist layer protects a region where the recess 170 is not required to be formed, and then the first thin film encapsulation layer 161, the top electrode 150, and the functional layer 140 over the pixel defining layer 120 are etched by, for example, dry etching, so as to form the recess 170. Subsequently, the patterned photoresist layer may be removed, and a second thin film encapsulation layer 162 is formed.

The second thin film encapsulation layer 162 is also an inorganic film layer, and may be made of silicon oxide (SiO) ₂ ) Silicon nitride (SiN), aluminum oxide (Al) ₂ O ₃ ) Titanium oxide (Ti)O ₂ ) Any one or a combination of more of them.

In this embodiment, the film encapsulation layer 160 may further include a third film encapsulation layer 163 and a fourth film encapsulation layer 164, where the third film encapsulation layer 163 is an organic film layer, and the fourth film encapsulation layer 164 is an inorganic film layer.

In summary, in the embodiment, the recess is formed above the pixel defining layer, and the recess penetrates through the functional layer, the top electrode and the first thin film encapsulation layer, and the recess is filled with the second thin film encapsulation layer made of an inorganic material to form the anchoring structure. In addition, a first film packaging layer and a second film packaging layer are formed at the pixel opening, a recess is formed in the first film packaging layer above the pixel definition layer, and the first film packaging layer in a partial area above the pixel definition layer is dug out, so that the thickness of the inorganic film layer in a partial area above the pixel definition layer is reduced, and the bending performance is improved.

EXAMPLE five

Fig. 9 is a schematic cross-sectional view of an OLED display panel according to a fifth embodiment of the invention. As shown in fig. 9, the OLED display panel includes a substrate 100, and a bottom electrode 110 (an anode in this embodiment), a pixel defining layer 120, a functional layer 140, a top electrode 150 (a cathode in this embodiment), and a thin film encapsulation layer 160 formed on the substrate 100.

In this embodiment, the cross-sectional width of the end (bottom end) of the pixel definition layer 120 close to the substrate 100 is smaller than the cross-sectional width of the end (top end) of the pixel definition layer 120 far from the substrate 100, that is, the pixel definition layer 120 has a structure with a wide top and a narrow bottom. Specifically, the cross section (longitudinal section) of the recess 170 perpendicular to the substrate surface and parallel to the width direction of the pixel definition layer is an inverted trapezoid. It will be appreciated that in actual production, some deviation is allowed between the actual shape (and size) and the design shape (and size) of each product. Generally, the use requirements can be met as long as the actual shape (and size) of the product is within the allowable deviation range of the designed shape (and size). For example, the side wall of the recess may be a straight wall, and the included angle between the straight wall and the bottom wall is less than 90 degrees, for example, between 30 and 80 degrees; the side wall of the recess can also be an arc wall with some radians, and when the side wall is the arc wall, the included angle between the tangent line and the bottom wall is less than 90 degrees, such as between 30-80 degrees.

Since the pixel defining layer 120 has a structure with a wide top and a narrow bottom, when the functional layer 140 and the top electrode 150 are formed subsequently, the functional layer 140 and the top electrode 150 are not easily filled into the bottom corner of the pixel defining layer 120, the functional layer 140 and the top electrode 150 in the pixel opening 130 are disconnected from the functional layer 140 and the top electrode 150 in the pixel defining layer 120, a recess 170 (refer to fig. 10b for emphasis) is formed between the pixel defining layer 120 and the functional layer in the pixel opening, the recess 170 is located on two sides of the pixel defining layer 120 in the width direction, and the thin film encapsulation layer 160 can be filled in the recess 170 to form an anchor structure, thereby improving the shear resistance of the OLED.

Since the top electrode 150 at the pixel opening 130 is disconnected from the top electrode 150 above the pixel defining layer 120, correspondingly, the pixel defining layer 120 around the pixel opening 130 can be set to be a segmented structure, as shown in fig. 11, four segments of pixel defining layers 120 (one segment of pixel defining layer 120 is set at each side) can be set around the pixel opening 130, and the top electrode 150 can be evaporated at a position between two adjacent segments of pixel defining layers, so that the top electrode 150 can be ensured to be electrically connected. Alternatively, a plurality of segments of the pixel defining layer 120 are disposed on each side of the pixel opening 130. Of course, the shape and number of the pixel defining layer 120 are not limited to the above examples, for example, referring to fig. 12, a segment of the pixel defining layer 120 may be disposed around the pixel opening 130, and the pixel defining layer 120 has a gap for electrically connecting the top electrode 150.

The thin film encapsulation layer 160 is formed by alternately arranging organic film layers and inorganic film layers. Specifically, in the present embodiment, as shown in fig. 9, the film encapsulation layer 160 includes six layers of sequentially stacked first film encapsulation layer 161, second film encapsulation layer 162, and third film encapsulation layerLayer 163, fourth thin film encapsulation layer 164, fifth thin film encapsulation layer 165, sixth thin film encapsulation layer 166. The first film encapsulation layer 161, the third film encapsulation layer 163 and the fifth film encapsulation layer 165 are organic film layers, and the second film encapsulation layer 162, the fourth film encapsulation layer 164 and the sixth film encapsulation layer 166 are inorganic film layers, that is, the first to sixth encapsulation film layers adopt a mode of alternately distributing organic film layers and inorganic film layers. The second thin film encapsulation layer 162, the fourth thin film encapsulation layer 164, and the sixth thin film encapsulation layer 166 may be silicon oxide (SiO) ₂ ) Silicon nitride (SiN), aluminum oxide (Al) ₂ O ₃ ) Titanium oxide (TiO) ₂ ) Any one or a combination of more of them. It should be understood that the thin film encapsulation layer 160 is not limited to a six-layer structure, and may be composed of more layers, for example, eight-layer structures (e.g., four organic layers + four inorganic layers), or fewer layers, for example, four-layer structures (e.g., two organic layers + two inorganic layers), and the number of the thin film encapsulation layers and the thickness of each layer may be adjusted according to actual needs, which is not limited by the present invention.

Preferably, as shown in fig. 9, the inorganic film layers (in this embodiment, the second thin film encapsulation layer 162 and the fourth thin film encapsulation layer 164) except for the topmost layer in the thin film encapsulation layer 160 are all of a segmented structure, that is, the inorganic film layers except for the topmost layer are not the entire film layer, but have some openings, so that two adjacent organic film layers are connected to each other through the openings to form a closed structure, thereby further improving the shear resistance.

Although the above description has been made in a case where all inorganic layers except the topmost layer in the film encapsulation layer 160 are of a segmented structure, it should be understood that all inorganic layers except the topmost layer may be of segmented structures only partially, and the upper and lower organic layers of the segmented structure may be connected to each other, for example, as shown in fig. 13, the film encapsulation layer 160 includes eight layers of first to eighth film encapsulation layers 161 to 168, which are sequentially stacked, wherein the first film encapsulation layer 161, the third film encapsulation layer 163, the fifth film encapsulation layer 165, and the seventh film encapsulation layer 167 are organic layers, the second film encapsulation layer 162, the fourth film encapsulation layer 164, the sixth film encapsulation layer 166, and the eighth film encapsulation layer 168 are inorganic layers, and the second segmented film encapsulation layer 162 and the fourth segmented film encapsulation layer 164 are organic layers, the sixth thin film encapsulation layer 166 and the eighth thin film encapsulation layer 168 adopt a whole surface structure, so that the anti-shearing force can be improved to a certain extent, and the multiple inorganic film layers (here, the sixth thin film encapsulation layer 166 and the eighth thin film encapsulation layer 168) arranged above the pixel definition layer 120 are also beneficial to ensuring the effect of blocking water and oxygen at the position.

The following describes a manufacturing process of the above OLED display panel with reference to fig. 10a to 10 b.

First, as shown in fig. 10a, a substrate 100 is provided, a conductive thin film is formed on the substrate 100, and the conductive thin film is patterned to form a plurality of bottom electrodes 110, wherein the plurality of bottom electrodes 110 are respectively connected to drain electrodes of driving transistors of different pixel units.

Next, as shown in fig. 10a, a polymer thin film is prepared on the bottom electrode 110 by a method such as spin coating, and a pixel defining layer 120 is formed in a corresponding patterning manner according to the properties of the polymer, the pixel defining layer 120 being provided with a pixel opening 130 corresponding to a light emitting region. Specifically, the polymer film may be patterned by exposure development (when the polymer is a photosensitive polymer) or by exposure development and dry etching (when the polymer is a non-photosensitive polymer) to form the plurality of pixel openings 130. In this embodiment, the pixel defining layer 120 has a structure with a wide top and a narrow bottom, so the pixel defining layer 120 with a wide top and a narrow bottom can be formed by using a negative photoresist as a mask and an exposure and development process.

Next, the functional layer 140 and the top electrode 150 are sequentially formed by, for example, an evaporation method or an inkjet printing method. Since the pixel defining layer 120 has a structure with a wide top and a narrow bottom, a recess is formed at a corner near the bottom electrode 110, and the functional layer 140 and the top electrode 150 have relatively thin thicknesses and are not easy to fill the recess, so that after the functional layer 140 and the top electrode 150 are formed, a recess 170 (a fillable gap) is formed between the pixel defining layer 120 and the functional layer in the pixel opening, as shown in fig. 10 b. Preferably, for the top emission device, after the top electrode 150 is formed, a light coupling layer (CPL) is further formed on the top electrode 150 by, for example, an evaporation method or an inkjet printing method, so as to improve light extraction efficiency. In addition, when the functional layer 140, the top electrode 150, and the CPL are formed by vapor deposition, an FMM (vapor deposition MASK having a small opening) may be used, and an OPEN MASK (vapor deposition MASK having a large opening) may also be used, and since the pixel defining layer 120 has a structure (for example, an inverted trapezoidal structure) having a wide top and a narrow bottom, the film layer in the light emitting region and the film layer in the pixel defining layer may be separated by vapor deposition of the functional layer 140, the top electrode 150, and the CPL itself using the OPEN MASK, and when the functional layer 140, the top electrode 150, and the CPL are vapor deposited using the OPEN MASK, the film layers are also formed on the upper surface of the pixel defining layer 120.

After the top electrode 150 is formed, as shown in fig. 10b, a thin film encapsulation layer 160 is formed by a method such as an evaporation method or an inkjet printing method. Since the recess 170 is formed between the pixel defining layer 120 and the functional layer 140, the thin film encapsulation layer 160 fills the recess 170 and covers the top electrode 150, and thus, the thin film encapsulation layer 160 filled in the recess 170 constitutes a plurality of anchoring structures, which effectively enhances the shear resistance of the OLED display panel and prevents the separation or displacement between the thin film encapsulation layer and the top electrode and between the film layers inside the functional layer.

Specifically, in this embodiment, the film encapsulation layer 160 includes a first film encapsulation layer 161, a second film encapsulation layer 162, a third film encapsulation layer 163, a fourth film encapsulation layer 164, a fifth film encapsulation layer 165, and a sixth film encapsulation layer 166, which are sequentially stacked. The second thin film encapsulation layer 162 and the fourth thin film encapsulation layer 164 are patterned to form a segmented structure, which is beneficial to the interconnection of the three organic film layers of the first thin film encapsulation layer 161, the third thin film encapsulation layer 163 and the fifth thin film encapsulation layer 165 to form a closed structure, and can further enhance the shear resistance of the OLED display panel. The inorganic layer (in this embodiment, the sixth thin film encapsulation layer 166) at the topmost layer of the thin film encapsulation layers 160 adopts a full-surface structure, so as to achieve a better water and oxygen blocking effect.

FIG. 14 is a schematic cross-sectional view of an OLED display panel according to an embodiment of the present invention. As shown in fig. 14, the pixel defining layer 120 may further have a hole 120 'formed therein, and the hole 120' has a larger cross-sectional width at an end (bottom end) close to the substrate 100 than at an end (top end) far from the substrate 100. The hole 120' may penetrate through the pixel defining layer 120 to expose the bottom electrode 110, or may penetrate through only a portion of the thickness of the pixel defining layer 120. As a non-limiting example, a cross section (longitudinal section) of the hole 120 'perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer is an isosceles trapezoid, and preferably, the longitudinal section of the hole 120' is an isosceles trapezoid. Since the hole 120 ' and the pixel opening 130 are both narrow at the top and wide at the bottom, the hole 120 ' and the pixel opening 130 can be formed simultaneously by one-step patterning process, such as an exposure-development process and/or a dry etching process, that is, the hole 120 ' is also formed in the pixel definition layer 120 while the pixel definition layer 120 is formed, so that the mask cost can be saved and the process flow can be simplified. The presence of the holes 120' can further improve the adhesion of the encapsulating film layer 160 and prevent separation or displacement between the film encapsulating layer and the cathode and between the film layers within the functional layer.

EXAMPLE six

The above embodiments describe a method of forming the recesses by a patterning process including an exposure development process and/or an etching process. In this embodiment, after the functional layer and the top electrode are formed, i.e., after the pixel unit is formed, a laser (or dry etching, etc.) process is used to destroy part of the OLED film layer in the inactive area in the product to form a recess, so as to create an area where the thin film encapsulation layer is in direct contact with the pixel definition layer below, thereby improving the adhesion of the encapsulation film layer.

Fig. 15 is a schematic diagram of the distribution of the recesses in the present embodiment, and as shown in fig. 15, one recess 170 is distributed at each of four corners of a pixel unit composed of a red sub-pixel R, a green sub-pixel G, and a blue sub-pixel B. Of course, the embodiment of the present invention does not limit the number and the distribution position of the recesses 170, for example, a plurality of recesses 170 may be distributed at four corners of the pixel unit, or the recesses 170 may be distributed at only one corner of the pixel unit. The depressions 170 may be uniformly distributed on the substrate or non-uniformly distributed on the substrate. The recess 170 may correspond to a position of the pixel definition layer, or may correspond to a position other than the pixel definition layer. Taking the position of the recess corresponding to the pixel defining layer as an example, the recess may be a pixel defining layer penetrating through a part of the thickness or the whole thickness, or may be a pixel defining layer penetrating through the whole thickness and a planarization layer penetrating through a part of the thickness or the whole thickness. Of course, the recess may also extend through the top electrode and the functional layer above the pixel defining layer. The invention does not limit the depth of the recess, as long as the part corresponding to the invalid area in the product is knocked down to form the recess, and the technicians in the field can correspondingly select the proper depth according to the specific product design condition as long as the normal luminescence is not influenced.

Specifically, as shown in fig. 16, the mask can be used to block light, and laser is used to perform full-panel scanning, so that the laser passing through the mask can destroy the film layer in the target area, and a recess is formed at the destroyed point, so that the thin film encapsulation layer directly contacts with the pixel definition layer below through the recess, thereby increasing the adhesion force. The destroying action may be performed by a laser cutting device, and a person skilled in the art may set a specific laser energy and select a suitable mask according to specific needs, which is not limited herein.

In addition, the present embodiment does not limit the specific shape of the depressions formed by the above method, the shape of the depressions 170 may be preferably one or any combination of a cylinder, an elliptic cylinder, a circular truncated cone, a rectangular parallelepiped, and a cube, and the depressions 170 may be irregular. The shape (and size) of the depressions in each region may be the same or different.

EXAMPLE seven

Fig. 17 is a schematic cross-sectional view of an OLED display panel according to a seventh embodiment of the invention. As shown in fig. 17, the OLED display panel includes a substrate 100, and a bottom electrode 110 (an anode in this embodiment), a pixel defining layer 120, a functional layer 140, a top electrode 150 (a cathode in this embodiment), and a thin film encapsulation layer 160 formed on the substrate 100. In addition, the OLED display panel further includes a boss 180 formed on the pixel defining layer 120.

As shown in conjunction with fig. 18a and 18b, the pixel defining layer 120 is provided with a pixel opening 130 corresponding to a light emitting region. The OLED display panel includes a light emitting region and a non-light emitting region, the pixel opening 130 of the pixel defining layer 120 is used to define the light emitting region and the non-light emitting region, a region corresponding to the pixel opening 130 is the light emitting region, and a region except the pixel opening 130 is the non-light emitting region. The functional layer 140 and the top electrode 150 may be disposed not only in the pixel opening 130 but also above the pixel defining layer 120, and only a portion corresponding to the pixel opening 130 emits light to constitute a light emitting region.

The cross-sectional width of the pixel defining layer 120 at one end (bottom end) close to the substrate 100 is greater than that at one end (top end) far from the substrate 100. The cross-sectional width of the end (bottom end) of the projection 180 near the pixel defining layer 120 is smaller than the cross-sectional width of the end (top end) thereof far from the pixel defining layer 120. Specifically, in this embodiment, a cross section (longitudinal section) of the pixel defining layer 120 perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer is a regular trapezoid, a cross section (longitudinal section) of the protrusion 180 perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer is an inverted trapezoid, and the bottom end of the protrusion 180 contacts with the top end of the pixel defining layer 120. And, a sectional width of the top end of the pixel defining layer 120 is greater than a sectional width of the top end of the pixel defining layer 120. Therefore, the recess 170 is formed between the pixel defining layer 120 and the boss 180, and the thin film encapsulation layer flows into the recess 170 to form an anchoring structure in the thin film encapsulation process, so as to achieve the effects of improving the adhesion between the thin film encapsulation layer and the substrate and preventing the OLED film layer from being separated. On the other hand, the boss 180 can also play a supporting role, for example, when a functional layer is formed by subsequent evaporation, the boss can play a certain supporting role on an evaporation mask, and if a glass cover plate needs to be formed in a hard screen, the boss also has a certain supporting role on the glass cover plate, so that the glass cover plate is prevented from being broken in the pressing process.

The longitudinal section of the pixel defining layer 120 is preferably an isosceles trapezoid, and the longitudinal section of the projection 180 is preferably an isosceles trapezoid. In a specific implementation, the longitudinal section of the pixel defining layer 120 may have other shapes, for example, the longitudinal section of the pixel defining layer 120 may have other shapes, such as a shape with a narrow top and a wide bottom except a regular trapezoid, an inverted trapezoid, etc., and the longitudinal section of the projection 180 may also have a shape with a wide top and a narrow bottom except an inverted trapezoid. It is understood that the depression 170 may be formed regardless of the shape of the pixel defining layer 120, as long as the cross-sectional width of the end (bottom end) of the projection 180 near the pixel defining layer 120 is smaller than the cross-sectional width of the end (top end) thereof far from the pixel defining layer 120.

The following describes a manufacturing process of the above OLED display panel with reference to fig. 18a to 18 b.

First, as shown in fig. 18a, a substrate 100 is provided, a conductive film is formed on the substrate 100, and the transparent conductive film is patterned to form a plurality of bottom electrodes 110, wherein the plurality of bottom electrodes 110 are respectively connected to drain electrodes of driving transistors of different pixel units.

Next, as shown in fig. 18a, a polymer thin film is prepared on the bottom electrode 110 by a method such as spin coating, and a pixel defining layer 120 is formed in a corresponding patterning manner according to the properties of the polymer, the pixel defining layer 120 being provided with a pixel opening 130 corresponding to a light emitting region. Specifically, the polymer film may be patterned by a method of exposure development (when the polymer is a photosensitive polymer) or by a method of exposure development and dry etching (when the polymer is a non-photosensitive polymer), thereby forming the plurality of pixel openings 130.

Referring to fig. 18b, after forming the pixel defining layer 120, a polymer thin film is again prepared on the pixel defining layer 120 by, for example, spin coating, and a boss 180 is formed in a corresponding patterning manner according to the properties of the polymer, wherein the boss 180 is disposed on the pixel defining layer 120. Specifically, the polymer thin film may be patterned by a method of exposure development (when the polymer is a photosensitive polymer) or by a method of exposure development and dry etching (when the polymer is a non-photosensitive polymer), thereby forming the mesa 180.

The material of the protrusion 180 and the material of the pixel defining layer 120 may be the same or different. In the case where both are made of the same photosensitive polymer, the boss 180 and the pixel defining layer 120 may be formed separately in the following manner: firstly, forming a regular-trapezoid pixel defining layer by using a positive photoresist as a mask and utilizing an exposure and development process; then, the negative photoresist is used as a mask, and the inverse trapezoidal boss 180 is formed by an exposure and development process. The total thickness (height) of the pixel defining layer 120 and the projection 180 is, for example, between 2 μm and 8 μm, which is advantageous to ensure that the thickness is not too high to affect the flexibility of the display panel, and to ensure that the thickness is not too small to affect the definition and support functions of the pixel defining layer.

Then, the thin film encapsulation layer 160 is formed by, for example, evaporation or inkjet printing. Due to the existence of the recess 170, the thin film encapsulation layer 160 can fill the recess 170, so that the thin film encapsulation layer 160 filled in the recess 170 constitutes a plurality of anchoring structures, thereby effectively enhancing the shear resistance of the OLED display panel and avoiding the separation or displacement between the thin film encapsulation layer and the top electrode and between the film layers inside the functional layer. The film package preferably adopts a combination of an organic material and an inorganic material, for example, a laminated structure of an inorganic material/an organic material/an inorganic material is adopted, and specifically, the following combination modes can be adopted: silicon nitride/organic material/silicon nitride; alumina + silicon nitride/organic material/silicon nitride + alumina; silicon oxide + silicon nitride/organic material/silicon nitride + silicon oxide.

In a specific implementation, the boss 180 may further have a boss opening (not shown) formed therein, and a cross-sectional width of an end (bottom end) of the boss opening close to the substrate 100 is larger than a cross-sectional width of an end (top end) of the boss opening far from the substrate 100. The boss opening may extend through the boss 180 and the pixel defining layer 120, may extend through only a portion of the thickness of the boss 180, and may extend through the boss 180 and a portion of the thickness of the pixel defining layer 120. Of course, the bump opening may also be a planarization layer that extends through a portion of the thickness of the pixel definition layer 120 and then extends downward, or may also extend through the entire planarization layer after extending through the pixel definition layer 120 and then exposing a film layer (such as a passivation layer) below the planarization layer. The cross section of the boss opening can be circular, oval, triangular, rectangular or other polygonal shapes. The boss opening is preferably in the shape of a regular trapezoid in a cross section (longitudinal section) perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer. The bosses 180 and the boss openings can be simultaneously formed through a one-step patterning process, such as an exposure and development process and/or a dry etching process, that is, the boss 180 is formed while the boss opening is also formed in the boss 180, so that the mask cost can be saved and the process flow can be simplified. The presence of the boss openings can further improve the adhesion of the encapsulating film layer 160 and avoid separation or displacement between the film encapsulating layer and the cathode and between the film layers within the functional layer.

Example eight

FIG. 19 is a schematic cross-sectional view of an OLED display panel according to an embodiment of the present invention. As shown in fig. 19, the OLED display panel includes a substrate 100, and a bottom electrode 110 (an anode in this embodiment), a pixel defining layer 120, a functional layer 140, a top electrode 150 (a cathode in this embodiment), and a thin film encapsulation layer 160 formed on the substrate 100. In addition, the OLED display panel further includes a boss 180 formed on the pixel defining layer 120.

As shown in fig. 20a and 20b, the pixel defining layer 120 is provided with a pixel opening 130 corresponding to a light emitting region. The OLED display panel includes a light emitting region and a non-light emitting region, the pixel opening 130 of the pixel defining layer 120 is used to define the light emitting region and the non-light emitting region, a region corresponding to the pixel opening 130 is the light emitting region, and a region except the pixel opening 130 is the non-light emitting region. The functional layer 140 and the top electrode 150 may be disposed not only in the pixel opening 130 but also above the pixel defining layer 120, and only a portion corresponding to the pixel opening 130 emits light to constitute a light emitting region.

The thin film encapsulation layer 160 is formed by alternately arranging organic film layers and inorganic film layers. This implementationIn one example, the film encapsulation layer 160 includes three layers, namely a first film encapsulation layer 161, a second film encapsulation layer 162 and a third film encapsulation layer 163. The first thin film encapsulation layer 161 and the third thin film encapsulation layer 163 are inorganic film layers, and the second thin film encapsulation layer 162 is an organic film layer. Among them, the first thin film encapsulation layer 161 and the third thin film encapsulation layer 163 may employ silicon oxide (SiO) ₂ ) Silicon nitride (SiN), aluminum oxide (Al) ₂ O ₃ ) Titanium oxide (TiO) ₂ ) Any one or a combination of more of them. Preferably, the first thin film encapsulation layer 161 and the third thin film encapsulation layer 163, which are both inorganic film layers, contact each other (without the second thin film encapsulation layer 162) above the bump 180, and the first thin film encapsulation layer 161, the second thin film encapsulation layer 162, and the third thin film encapsulation layer 163 are sequentially stacked at other positions. Therefore, the bonding force of the inorganic film layer at the position of the boss 180 is strong, and the anti-shearing force of the OLED can be improved. The total thickness (height) of the pixel defining layer 120 and the bump 180 is, for example, between 2 μm and 8 μm, the total thickness (height) of the pixel defining layer 120 and the bump 180 is, for example, between 3 μm and 4 μm, the thickness of the first thin film encapsulation layer 161 is, for example, between 0.5 μm and 1.5 μm, the thickness of the second thin film encapsulation layer 162 is, for example, between 2 μm and 3 μm, and the sum of the thicknesses of the first thin film encapsulation layer 161 and the second thin film encapsulation layer 162 is equal to the sum of the thicknesses of the pixel defining layer 120, the bump 180, and the first thin film encapsulation layer 161, that is, the top surface of the first thin film encapsulation layer 161 above the bump 180 is flush with the top surface of the second thin film encapsulation layer 162 at other positions, so that the first thin film encapsulation layer 161 above the bump 180 is in direct contact with the third thin film encapsulation layer 163.

Further, the cross-sectional width of the pixel defining layer 120 at an end (bottom end) close to the substrate 100 is larger than that at an end (top end) far from the substrate 100. The cross-sectional width of the end (bottom end) of the projection 180 near the pixel defining layer 120 is smaller than the cross-sectional width of the end (top end) thereof far from the pixel defining layer 120. Specifically, in the present embodiment, a cross section (longitudinal section) of the pixel defining layer 120 perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer is a regular trapezoid, a cross section (longitudinal section) of the projection 180 perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer is an inverted trapezoid, and the bottom end of the projection 180 contacts with the top end of the pixel defining layer 120. And, a sectional width of the top end of the pixel defining layer 120 is greater than a sectional width of the top end of the pixel defining layer 120. Therefore, the recess 170 is formed between the pixel defining layer 120 and the protrusion 180, and the thin film encapsulation layer flows into the recess 170 to form an anchoring structure during the thin film encapsulation process, thereby achieving the effects of improving the adhesion between the thin film encapsulation layer and the substrate and preventing the separation of the OLED film layer. On the other hand, the boss 180 can also play a supporting role, for example, when a functional layer is formed by subsequent evaporation, it can play a certain supporting role for an evaporation mask (mask), and if a glass cover plate needs to be formed in a hard screen, it also has a certain supporting role for the glass cover plate, so as to prevent the glass cover plate from being broken in the pressing process.

The longitudinal section of the pixel defining layer 120 is preferably an isosceles trapezoid, and the longitudinal section of the projection 180 is preferably an isosceles trapezoid. It should be understood that in practical implementation, the longitudinal section of the pixel defining layer 120 may have other shapes, for example, the longitudinal section of the pixel defining layer 120 may have other shapes, such as a shape with a narrow top and a wide bottom except a regular trapezoid, an inverted trapezoid, etc., and the longitudinal section of the projection 180 may also have a shape with a wide top and a narrow bottom except an inverted trapezoid.

The following describes a manufacturing process of the above OLED display panel with reference to fig. 20a to 20 b.

First, as shown in fig. 20a, a substrate 100 is provided, a conductive film is formed on the substrate 100, and the conductive film is patterned to form a plurality of bottom electrodes 110, wherein the plurality of bottom electrodes 110 are respectively connected to drain electrodes of driving transistors of different pixel units.

Next, as shown in fig. 20a, a polymer film is prepared on the bottom electrode 110 by a method such as spin coating, and a pixel defining layer 120 is formed in a corresponding patterning manner according to the properties of the polymer, the pixel defining layer 120 being provided with a pixel opening 130 corresponding to a light emitting region. Specifically, the polymer film may be patterned by a method of exposure development (when the polymer is a photosensitive polymer) or by a method of exposure development and dry etching (when the polymer is a non-photosensitive polymer), thereby forming the plurality of pixel openings 130. Similarly, after the pixel defining layer 120 is formed, a polymer film is prepared on the pixel defining layer 120 again by, for example, spin coating, and a boss 180 is formed in a corresponding patterning manner according to the property of the polymer, wherein the boss 180 is disposed on the pixel defining layer 120. Specifically, the polymer film may be patterned by a method of exposure development (when the polymer is a photosensitive polymer) or by a method of exposure development and dry etching (when the polymer is a non-photosensitive polymer), thereby forming the mesa 180. The material of the bump 180 and the material of the pixel defining layer 120 may be the same or different. In the case where both are made of the same photosensitive polymer, the boss 180 and the pixel defining layer 120 may be formed separately in the following manner: firstly, forming a positive trapezoidal pixel defining layer by using a positive photoresist as a mask and utilizing an exposure and development process; then, the negative photoresist is used as a mask, and the inverse-trapezoidal boss 180 is formed by an exposure and development process. The total thickness (height) of the pixel defining layer 120 and the mesa 180 is, for example, between 2 μm and 8 μm.

Next, as shown in fig. 20b, a functional layer 140 and a top electrode 150 are sequentially formed by a method such as evaporation or inkjet printing, and a first thin film encapsulation layer 161 is formed by a method such as CVD. The first thin film encapsulation layer 161 is an inorganic film layer, and may be made of silicon oxide (SiO) ₂ ) Silicon nitride (SiN), aluminum oxide (Al) ₂ O ₃ ) Titanium oxide (TiO) ₂ ) Any one or a combination of more of them. The thickness of the first thin film encapsulation layer 161 is between 0.5 μm and 1.5 μm.

Subsequently, as shown in fig. 19, a second thin film encapsulation layer 162 and a third thin film encapsulation layer 163 are formed. The second encapsulation thin film layer 162 is an organic film layer, and may fill the recess 170 and contact the pixel defining layer 120. The thickness of the second thin film encapsulation layer 162 is between 2 μm and 3 μm. The third thin film encapsulation layer 162 is also an inorganic film layer, and may be made of silicon oxide (SiO) ₂ ) Silicon nitride (SiN), aluminum oxide (Al) ₂ O ₃ ) Titanium oxide (TiO) ₂ ) Any one or a combination of more of them.

In this embodiment, the top surface of the second encapsulation film layer 162 is flush with the top surface of the first film encapsulation layer 161 above the boss, and the top surface of the first film encapsulation layer 161 is exposed, so that when the third film encapsulation layer 163 is formed subsequently, the third film encapsulation layer 163, which is also an inorganic film layer, is in contact with the first film encapsulation layer 161 above the boss 180, which is equivalent to bonding the inorganic film layer at the boss 180 (where the organic film layer is in contact with the inorganic film layer at other positions (such as the third film encapsulation layer 163 and the second film encapsulation layer 162)), and experiments show that such a bonding manner is beneficial to improving the shear resistance of the OLED.

In a specific implementation, the boss 180 may further have a boss opening (not shown) formed therein, and a cross-sectional width of an end (bottom end) of the boss opening close to the substrate 100 is larger than a cross-sectional width of an end (top end) of the boss opening far from the substrate 100. The mesa openings may extend through the mesa 180 and a portion or all of the thickness of the pixel defining layer 120, or only through a portion of the thickness of the mesa 180. The cross section of the boss opening can be circular, oval, triangular, rectangular or other polygonal shapes. The cross section (longitudinal section) of the boss opening perpendicular to the substrate surface and parallel to the width direction of the pixel defining layer is preferably in a regular trapezoid shape. The bosses 180 and the boss openings may be formed simultaneously by a patterning process, such as an exposure and development process and/or a dry etching process, that is, the boss 180 is formed while the boss opening is formed in the boss 180, which may save the mask cost and simplify the process flow. The presence of the boss openings can further improve the adhesion of the encapsulating film layer 160 and avoid separation or displacement between the film encapsulating layer and the cathode and between the film layers within the functional layer.

Example nine

As shown in fig. 21, the present embodiment provides an OLED display panel, which includes a substrate 100, and a bottom electrode, a pixel defining layer 120, a functional layer, a top electrode and a thin film encapsulation layer formed on the substrate 100; the pixel defining layer 120 is formed with a plurality of pixel openings, and the bottom electrode, the functional layer and the top electrode located in the pixel openings form a pixel unit.

The OLED display panel further includes a bank formed on the substrate 100 and surrounding the pixel defining layer 120, the bank having a plurality of recesses formed therein.

The bank includes, for example, a first bank 191 and a second bank 192, the first bank 191 surrounding the pixel defining layer 120, and the second bank 192 surrounding the first bank 191.

The thin film encapsulation layer includes, for example, a first thin film encapsulation layer 161 and a second thin film encapsulation layer 162 disposed on an upper surface of the first thin film encapsulation layer 161. The first film encapsulation layer 161 is an inorganic film layer, and the second film encapsulation layer 162 is an organic film layer.

At least one of the first bank 191 and the second bank 192 has one or more depressions 160, for example, the first bank 191 has one or more depressions 160, the second bank 192 has one or more depressions 160, or both the first bank 191 and the second bank 192 have depressions 160. The recess 160 is, for example, a groove or a through hole, and the shape of the recess 160 is one of a cylinder, an elliptic cylinder, a circular truncated cone, an inverted circular truncated cone, a rectangular parallelepiped, or a cube, or any combination thereof. The depressions 160 formed on the upper surfaces of the second bank 192 and the first bank 191 prevent the organic paste from overflowing when the organic film is ink-jet printed, disperse the stress when the panel is bent, and enhance the adhesion of the inorganic layer.

The first and

second bank

191 and 192 may function as a dam to prevent diffusion of organic substances in the organic film layer when the organic film layer is formed. As shown in fig. 21, the organic substance in the organic film layer is blocked by the first bank 191 and/or the second bank 192. Further, the recess formed by the gap between the first bank 191 and the second bank 192 can be beneficial to prevent the overflow of organic matters.

In this embodiment, the organic film layer includes a polymer. Polymers include polyethylene terephthalate, polyimide, polycarbonate, epoxy, polyethylene, and/or polyacrylate, among others. The organic film layer may function to absorb stress and ensure flexibility. The material of the substrate comprises polyimide, polyethylene terephthalate or plastic.

The first bank 191 has, for example, a circular ring shape, an elliptical ring shape, or a polygonal ring shape such as a square ring shape, a rhombic ring shape, or a parallelogram ring shape in plan view. The second bank 192 is similar in structure to the first bank 191 and will not be described herein.

In one embodiment, the display device further comprises: a third thin film encapsulation layer 163 disposed on an upper surface of the second thin film encapsulation layer 162. In this embodiment, the first thin film encapsulation layer 161 and the third thin film encapsulation layer 163 include a metal oxide and/or a metal nitride. The metal oxide and/or metal nitride may include SiNx, Al ₂ O ₃ 、SiO ₂ And/or TiO ₂ 。

It should be understood that the shapes of the recesses 160 formed on the upper surfaces of the first and

second banks

191 and 192 may be the same or different, such as a portion having a circular shape and another portion having a square shape; alternatively, the shape between the openings of the first and

second dikes

191, 192 may be the same but the size may be different; further alternatively, the two recesses 160 may differ in shape and size. Furthermore, the recesses on both dikes may also be non-uniformly distributed in the dikes. The cross-sectional shape (a section parallel to the substrate direction) of the recess 160 is, for example, a circle, a triangle, a rectangle, a trapezoid, a rhombus, or an irregular shape.

The embodiment also provides a preparation method of the OLED display panel, which includes:

providing a substrate, wherein a bottom electrode, a pixel definition layer, a functional layer and a top electrode are formed on the substrate, a plurality of pixel openings are formed in the pixel definition layer, and the bottom electrode, the functional layer and the top electrode positioned in the pixel openings form a pixel unit;

a first bank 191 and a second bank 192 surrounding the pixel unit are formed on the substrate, the first bank 191 is disposed near the pixel unit, and the second bank 192 is disposed on a side of the first bank 191 away from the pixel unit; and

more than one opening is formed on at least one of the first and

second dams

191 and 192.

To sum up, the OLED display panel that this embodiment provided through one or more sunken that set up on the dykes and dams, prevents because the organic glue spills over when the organic film layer of inkjet printing, reduces because of the excessive TFE encapsulation that causes of organic film layer is invalid, has disperseed the stress when the screen body is buckled, strengthens inorganic layer adhesive force simultaneously.

It should be understood that although the present description describes embodiments, not every embodiment may include only a single embodiment, and such description is for clarity purposes only, and those skilled in the art will recognize that the embodiments described herein may be combined as a whole to form other embodiments as would be understood by those skilled in the art.

The above description is only for the purpose of describing preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are intended to fall within the scope of the appended claims.

Claims

1. The OLED display panel is characterized by comprising a substrate, and a bottom electrode, a pixel definition layer, a functional layer, a top electrode and a thin film packaging layer which are formed on the substrate; the pixel definition layer is provided with a plurality of pixel openings, and a bottom electrode, a functional layer and a top electrode which are positioned in the pixel openings form a pixel unit; the OLED display panel further comprises a boss formed on at least part of the pixel defining layer, the film packaging layer comprises a first film packaging layer, a second film packaging layer and a third film packaging layer, the first film packaging layer and the third film packaging layer are inorganic film layers, the second film packaging layer is an organic film layer, and the third film packaging layer above the boss is in contact with the first film packaging layer; the cross section width of one end, close to the pixel defining layer, of the boss is smaller than that of one end, far away from the pixel defining layer, of the boss, a recess is formed between the pixel defining layer and the boss, and the thin film packaging layer fills the recess.

2. The OLED display panel claimed in claim 1, wherein the projections have an inverted trapezoidal shape in a cross section perpendicular to the surface of the substrate and parallel to a width direction of the pixel defining layer.

3. The OLED display panel of claim 1, wherein the pixel defining layer has a greater cross-sectional width at an end thereof adjacent to the substrate than at an end thereof remote from the substrate.

4. The OLED display panel of claim 1, wherein said bosses further have boss openings formed therein, said boss openings extending at least partially through said bosses.

5. The OLED display panel of claim 4, further comprising a planarization layer formed on the substrate, the bottom electrode being formed on the planarization layer; the boss opening may also extend through a portion or all of the thickness of the pixel-defining layer, or the boss opening may also extend through a portion or all of the thickness of the pixel-defining layer and a portion or all of the thickness of the planarization layer.

6. The OLED display panel of claim 1, wherein one or more of said panels are formed on each pixel cell.

7. The OLED display panel of claim 1, wherein the panels are of the same material as the pixel defining layer.

8. The OLED display panel of claim 1, wherein a total thickness of the pixel defining layer and the mesa is between 2 μ ι η -8 μ ι η.

9. A preparation method of an OLED display panel is characterized by comprising the following steps:

providing a substrate; and

forming a bottom electrode, a pixel defining layer, a functional layer, a top electrode and a film packaging layer on the substrate, wherein the pixel defining layer is provided with a plurality of pixel openings, the OLED display panel is also provided with a plurality of bosses, the film packaging layer comprises a first film packaging layer, a second film packaging layer and a third film packaging layer, the first film packaging layer and the third film packaging layer are inorganic film layers, the second film packaging layer is an organic film layer, and the third film packaging layer above the bosses is in contact with the first film packaging layer; the cross section width of one end, close to the pixel definition layer, of the boss is smaller than that of one end, far away from the pixel definition layer, of the boss, a recess is formed between the pixel definition layer and the boss, and the thin film packaging layer fills the recess.