Display panel and method for manufacturing display panel

Abstract

The present application relates to a display panel and a method for preparing the display panel. The display panel includes a driving backplane, a plurality of first electrodes, a pixel defining layer, a light-emitting functional layer and a plurality of heat conversion units. The pixel defining layer includes a plurality of pixel openings, the pixel openings expose at least a portion of the first electrode, the light-emitting functional layer includes a plurality of light-emitting units, the light-emitting units are correspondingly arranged in the pixel openings, the heat conversion unit is sandwiched between the first electrode and the driving backplane, and the heat conversion unit is electrically connected to the first electrode, and the heat conversion unit has a middle area corresponding to the first electrode and an edge area surrounding the middle area; when laser irradiation is performed from the side of the driving backplane away from the first electrode to print the light-emitting functional layer, the heat temperature of the edge area after absorbing the laser is lower than the heat temperature of the middle area after absorbing the laser, thereby improving the evaporation rate of the solvent, making the evaporation rates of the edge area and the middle area tend to be consistent, and ensuring uniform deposition of the solute.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a display panel and a method for preparing the display panel. Background Art

[0002] OLED (Organic Light-Emitting Diode), also known as organic electroluminescence display, organic light-emitting semiconductor (Organic Electroluminescence Display, referred to as OLED). OLED display is equipped with three RGB (red, green, blue) color light-emitting layers, which are light-emitting films formed by patterning technology.

[0003] The main patterning processes include vacuum evaporation and inkjet printing. Inkjet printing is a non-contact patterning technology. Compared with the mature vacuum evaporation process for preparing OLED technology, inkjet printing technology has unique advantages. In actual application, the material utilization rate of vacuum evaporation is 5%-20%, while the material utilization rate of inkjet printing is about 90%, which is significantly improved.

[0004] Inkjet printing is to spray ink droplets onto designated locations on a substrate to directly form patterns. It does not require the use of expensive vacuum evaporation equipment and precision masks, and is not limited by equipment and large-size fine metal masks. It helps to realize large-size display panels, save materials, and reduce preparation costs.

[0005] When the light-emitting layer is deposited using inkjet printing technology, the evaporation rates of the solvent at different positions are different, resulting in different deposition thicknesses of the solute at the center and edge of the droplet, resulting in a "coffee ring" phenomenon, forming an uneven light-emitting film, reducing the quality of the light-emitting film, and affecting the display effect of the display panel. Summary of the invention

[0006] The present application provides a display panel and a method for preparing the display panel. When inkjet printing is used, uniform deposition of the solute is ensured to obtain a high-quality light-emitting film and improve the display effect of the display panel.

[0007] In the first aspect, the present application provides a display panel, comprising a driving backplane, a plurality of first electrodes arrayed on the driving backplane, a pixel defining layer and a light-emitting function layer, wherein the pixel defining layer comprises a plurality of pixel openings, wherein the pixel openings expose at least a portion of the first electrode, the light-emitting function layer comprises a plurality of light-emitting units, wherein the light-emitting units are correspondingly arranged in the pixel openings, the display panel comprises a plurality of heat conversion units, wherein the heat conversion units are sandwiched between the first electrode and the driving backplane, and the heat conversion units are electrically connected to the first electrode, and the heat conversion units have a middle area corresponding to the first electrode and an edge area surrounding the middle area; wherein, when laser irradiation is performed from the side of the driving backplane away from the first electrode to print the light-emitting function layer, the heat temperature of the edge area after absorbing the laser is lower than the heat temperature of the middle area after absorbing the laser.

[0008] In a possible implementation, the middle area of ​​the heat conversion unit is made of a first absorbing material, and the edge area is made of a second absorbing material. After the heat conversion unit is irradiated by the laser, the heat conversion efficiency of the first absorbing material is greater than the heat conversion efficiency of the second absorbing material.

[0009] In a possible implementation, the heat conversion unit includes a first heat conversion layer, the first heat conversion layer is connected to the driving back plate, and a protrusion is provided in the middle area of ​​the first heat conversion layer corresponding to the first electrode, and the protrusion abuts against the first electrode.

[0010] In a possible implementation, the heat conversion unit includes a second heat conversion layer, which is sandwiched between the first electrode and the first heat conversion layer; an avoidance through hole is provided in the middle area corresponding to the second heat conversion layer and the first electrode, and the protrusion passes through the avoidance through hole and abuts against the first electrode, wherein after the heat conversion unit is irradiated by the laser, the heat conversion efficiency of the first heat conversion layer is greater than the heat conversion efficiency of the second heat conversion layer.

[0011] In a possible implementation, the first heat conversion layer includes a composite wave-absorbing material of carbon nanotubes and reduced graphene oxide; and the second heat conversion layer includes a composite wave-absorbing material of carbon nanotubes and a metal matrix.

[0012] In a possible implementation manner, an orthographic projection area of ​​the heat conversion unit on the driving backplane is larger than an orthographic projection area of ​​the first electrode on the driving backplane.

[0013] In a possible implementation, a plurality of insulation units are included, and the insulation unit is arranged between two adjacent heat conversion units.

[0014] In the second aspect, the present application provides a method for preparing a display panel, comprising: providing a driving backplane; depositing a plurality of heat conversion units on the driving backplane; depositing a plurality of first electrodes on the plurality of heat conversion units; depositing a pixel defining layer on the plurality of first electrodes, the pixel defining layer comprising a plurality of pixel openings, the pixel openings exposing at least a portion of the first electrodes; performing laser irradiation from a side of the driving backplane away from the first electrodes; spraying a solvent in the plurality of pixel openings to print a light-emitting functional layer, the light-emitting functional layer comprising a plurality of light-emitting units, the light-emitting units being formed in the pixel openings; wherein the heat conversion unit has a middle region corresponding to the first electrode and an edge region surrounding the middle region, the heat temperature of the edge region after absorbing the laser is lower than the heat temperature of the middle region after absorbing the laser, so that the evaporation rates of the solvent in the middle region and the edge region tend to be consistent.

[0015] In a possible implementation, before depositing a plurality of first electrodes on the plurality of heat conversion units, the method further includes: depositing an insulating unit between two adjacent heat conversion units, wherein the insulating unit is connected to the driving backplane.

[0016] In a possible implementation, the heating temperature of the middle area and the heating temperature of the edge area of ​​the heat conversion unit are both lower than 85°C.

[0017] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0018] The display panel provided in the embodiment of the present application, i.e., the method for preparing a display panel, is provided with a heat conversion unit. Since the heat temperature of the edge area after absorbing the laser is lower than the heat temperature of the middle area after absorbing the laser, when inkjet printing is adopted, the evaporation rate of the solvent can be improved, so that the evaporation rates of the edge area and the middle area tend to be consistent, thereby ensuring uniform deposition of the solute, obtaining a high-quality light-emitting film, and improving the display effect of the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0021] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0022] Figure 1 A schematic cross-sectional view of a display panel provided in an embodiment of the present application;

[0023] Figure 2 It is a schematic diagram of solute solidification in the related art;

[0024] Figure 3 A schematic cross-sectional view of a display panel provided in an embodiment of the present application;

[0025] Figure 4 A schematic cross-sectional view of a display panel provided in an embodiment of the present application;

[0026] Figure 5 for Figure 4 The illustrated embodiment provides a schematic diagram of solute solidification;

[0027] Figure 6 A flow chart of a method for preparing a display panel provided in an embodiment of the present application.

[0028] Description of reference numerals:

[0029] 1. Driving backplane; 2. First electrode; 3. Pixel defining layer; 31. Pixel opening; 4. Light-emitting functional layer; 41. Light-emitting unit; 5. Second electrode; 6. Encapsulation layer; 61. First inorganic encapsulation layer; 62. Organic encapsulation layer; 63. Second inorganic encapsulation layer; 7. Heat conversion unit; 71. First heat conversion layer; 711. Protrusion; 72. Second heat conversion layer; 721. Avoidance through hole; 8. Insulation unit; A', solvent; B', solute; A, solvent; B, solute. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0031] The disclosure below provides many different embodiments or examples to implement different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0032] For ease of description, spatial relative terms may be used herein to describe the relative positional relationship or movement of one element or feature relative to another element or feature as shown in the figure, such as "inside", "outside", "inner side", "outer side", "below", "below", "above", "above", "front", "back", etc. Such spatial relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure undergoes a position flip or a posture change or a motion state change, then these directional indications also change accordingly, for example: an element described as "below other elements or features" or "below other elements or features" will subsequently be oriented as "above other elements or features" or "above other elements or features". Therefore, the example term "below..." may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions) and the spatial relative descriptors used herein are interpreted accordingly.

[0033] In order to solve the technical problem of different deposition thickness of solute at the center and edge of the droplet in the related art, the present application provides a display panel with a heat conversion unit. Since the heat temperature of the edge area after absorbing the laser is lower than the heat temperature of the middle area after absorbing the laser, when inkjet printing is adopted, the evaporation rate of the solvent can be improved, so that the evaporation rates of the edge area and the middle area tend to be consistent, thereby ensuring uniform deposition of the solute, obtaining a high-quality light-emitting film, and improving the display effect of the display panel.

[0034] First embodiment

[0035] Figure 1 A cross-sectional schematic diagram of a display panel provided in an embodiment of the present application is shown.

[0036] The embodiment of the present application provides a display panel, such as an OLED panel, which includes a driving backplane 1 , a plurality of first electrodes 2 arrayed on the driving backplane 1 , a pixel defining layer 3 and a light-emitting functional layer 4 .

[0037] The driving backplane 1 is, for example, a transistor circuit layer, which can control the current and drive the light-emitting functional layer 4 through the first electrode 2. The first electrode 2 is, for example, an anode.

[0038] The pixel defining layer 3 is deposited on the driving backplane 1 and the first electrode 2 , and the pixel defining layer 3 includes a plurality of pixel openings 31 , and the pixel openings 31 can expose at least a portion of the first electrode 2 so as to accommodate the light emitting functional layer 4 .

[0039] The light-emitting functional layer 4 includes a plurality of light-emitting units 41, and the plurality of light-emitting units 41 include, for example, a red light-emitting unit, a green light-emitting unit, and a blue light-emitting unit to meet the display requirements of the display panel. The light-emitting unit 41 can be patterned with pixels by maskless deposition and photolithography to form a thin film that can emit light of different colors, so that the light-emitting functional layer 4 has the characteristics of long life, low power consumption, and high brightness. The light-emitting unit 41 is made of, for example, a fluorescent material, a phosphorescent material, and a thermally activated delayed fluorescence (TADF) material.

[0040] Each light-emitting unit 41 is correspondingly arranged in the pixel opening 31, and the light-emitting unit 41 is connected to the first electrode 2. Since the colors of two adjacent light-emitting units 41 in the light-emitting functional layer 4 in the color display screen are different, when inkjet printing is used, it is necessary to prevent the solution from overflowing into the adjacent pixel pits, and an isolation area is formed by the pixel defining layer 3 to effectively avoid mutual interference. Among them, the pixel defining layer 3 uses photoresist resin as an isolation material to improve the isolation effect.

[0041] In this embodiment, the display panel further includes a second electrode 5 and an encapsulation layer 6. The second electrode 5 is stacked on the light-emitting functional layer 4 and the pixel defining layer 3. The second electrode 5 is, for example, a cathode. The second electrode 5 is, for example, lithium (Li), calcium (Ca), lithium fluoride / calcium (LiF / Ca), lithium fluoride / aluminum (LiF / Al), aluminum (Al), magnesium (Mg), silver (Ag), platinum (Pt), palladium (Pd), nickel (Ni), gold (Au), neodymium (Nd), iridium (Ir), chromium (Cr), barium fluoride (BaF), barium (Ba) or their compounds or mixtures, such as a mixture of Ag and Mg, etc., which is subject to actual conditions. The second electrode 5 is connected to the light-emitting functional layer 4. When the driving backplane 1 drives the first electrode 2, a complete circuit is formed through the first electrode 2, the light-emitting functional layer 4 and the second electrode 5 to achieve light emission.

[0042] The encapsulation layer 6 includes a first inorganic encapsulation layer 61, an organic encapsulation layer 62, and a second inorganic encapsulation layer 63 which are stacked in sequence. The first inorganic encapsulation layer 61 is connected to the second electrode 5. The first inorganic encapsulation layer 61 can prevent the light-emitting unit 41 formed by the organic light-emitting material from being invading by water and oxygen and failing. The second inorganic encapsulation layer 63 has the functions of stress release and flattening. Among them, the first inorganic encapsulation layer 61 and the second inorganic encapsulation layer 63 are, for example, ceramic-based encapsulation substrates, glass-based encapsulation substrates, etc., and the organic encapsulation layer 62 is, for example, a phenolic encapsulation substrate, a polyester encapsulation substrate, and an epoxy resin encapsulation substrate.

[0043] In order to achieve high resolution and colorization of passive matrix OLED, and better solve the problems of low resolution of electrode template and low device yield, an isolation column structure, namely pixel defining layer 3, is set. In the device preparation, no metal template is used. Instead, before forming the light-emitting functional layer 4 and the second electrode 5, an insulating partition, namely pixel defining layer 3, is formed on the driving backplane 1, and finally the different pixels of the light-emitting unit 41 are separated to realize the pixel array. Among them, the shape of the pixel defining layer 3 is the key to the isolation effect. The bottom of the pixel defining layer 3 is used to solve the short circuit problem of the first electrode 2. The trapezoidal pixel defining layer 3 is used to solve the short circuit problem of the light-emitting unit 41 between adjacent pixels. And the height of the pixel defining layer 3 is higher than the height of the light-emitting unit 41 to avoid the overflow of the light-emitting unit 41 and effectively intercept the solution of the light-emitting unit 41.

[0044] In this embodiment, the display panel includes a plurality of heat conversion units 7, which are sandwiched between the first electrode 2 and the driving backplane 1, and are electrically connected to the first electrode 2. The heat conversion unit 7 has a middle area corresponding to the first electrode 2 and an edge area surrounding the middle area, and the middle area and the edge area have different wave absorption heat conversion capabilities. For example, the wave absorption heat conversion capability of the middle area is greater than that of the edge area, so that when laser irradiation is performed from the side of the driving backplane 1 away from the first electrode 2 to print the light-emitting functional layer 4, the heat temperature of the edge area after absorbing the laser is lower than the heat temperature of the middle area after absorbing the laser, ensuring that the temperature difference between the middle area and the edge area can compensate for the evaporation rate advantage of the solvent A in the edge area, so that the evaporation rate of the solvent A tends to be consistent, and the solute B is uniformly deposited.

[0045] Among them, the middle area of ​​the heat conversion unit 7 is made of a first absorbing material, and the edge area is made of a second absorbing material. After the heat conversion unit 7 is irradiated by the laser, the heat conversion efficiency of the first absorbing material is greater than the heat conversion efficiency of the second absorbing material, so that the evaporation rate of the solvent A tends to be consistent, ensuring the uniform deposition of the solute B.

[0046] The first absorbing material is made of a composite absorbing material including at least carbon nanotubes (CNT), so that the heat conversion unit 7 has good conductivity. Carbon nanotubes have good mechanical properties, with a relative density of 1 / 6 of steel, a strength 100 times higher than steel, and an elastic strain of 5%-12%, which is about 60 times that of steel, so that its tensile strength can reach 100 times that of steel. Therefore, the super strong mechanical properties can greatly improve the strength and toughness of the composite absorbing material, and give the composite absorbing material new photoelectric properties, so as to meet the electrical connection between the heat conversion unit 7 and the first electrode 2 and the driving backplane 1.

[0047] Here, it should be noted that the second absorbing material may also be made of a composite absorbing material including at least carbon nanotubes (CNTs), and the specific material shall be subject to actual conditions.

[0048] In this embodiment, the orthographic projection area of ​​the heat conversion unit 7 on the driving back plate 1 is larger than the orthographic projection area of ​​the first electrode 2 on the driving back plate 1, so that the heat conversion unit 7 can completely wrap the cross-section of the first electrode 2 to ensure the electrical connection between the first electrode 2 and the heat conversion unit 7.

[0049] In this embodiment, the display panel includes a plurality of insulating units 8, and an insulating unit 8 is disposed between two adjacent heat conversion units 7. The insulating unit 8 is, for example, an inorganic insulating layer, which is used to fill the gap between the heat conversion units 7 and isolate two adjacent heat conversion units 7 to effectively avoid short circuits.

[0050] In related technologies, such as Figure 2 As shown, Figure 2 A schematic diagram of solute solidification in the related art is shown. When the light-emitting functional layer is deposited by inkjet printing technology and the light-emitting functional layer of the high-quality thin film is prepared, the droplet is spread and pinned, and the evaporation rate of the solvent A' in the edge area is greater than the evaporation rate of the solvent A' in the middle area. In order to compensate for the loss of solvent A' in the edge area, capillary flow from the middle area to the edge area will occur inside the droplet, and then the solute B' will be carried to the edge area. Finally, the solute B' is deposited to form an uneven thin film structure with a thick edge area and a thin middle area, namely a "coffee ring". When this morphology is formed, it will seriously affect the uniformity of the film layer of the light-emitting functional layer, resulting in abnormalities during display and reduced luminous efficiency.

[0051] The display panel provided in this embodiment utilizes the difference in heat absorption and heat conversion capability between the middle area and the edge area in the heat conversion unit 7 to form a temperature difference between the middle area and the edge area, thereby compensating for the evaporation rate advantage of the solvent A in the edge area (refer to Figure 5 As shown), the evaporation rate of solvent A tends to be consistent, ensuring uniform deposition of solute B, thereby obtaining a uniform film of light-emitting functional layer 4, avoiding abnormalities during display, and improving light-emitting efficiency.

[0052] Second embodiment

[0053] Figure 3 A schematic structural diagram of a display panel provided in an embodiment of the present application is shown.

[0054] The second embodiment of the present application also provides a display panel, which is similar to the display panel structure provided by the first embodiment, except that the heat conversion unit 7 includes a first heat conversion layer 71, the first heat conversion layer 71 is connected to the driving backplane 1, and a protrusion 711 is provided in the middle area corresponding to the first heat conversion layer 71 and the first electrode 2, and the protrusion 711 abuts against the first electrode 2, thereby improving the heating temperature of the middle area, increasing the evaporation rate of the solvent A, and avoiding too fast evaporation in the edge area, resulting in the "coffee ring" phenomenon.

[0055] The insulating unit 8 is used to fill and isolate two adjacent first heat conversion layers 71 and two adjacent protrusions 711 , and supports the first electrode 2 and the pixel defining layer 3 to achieve structural stability.

[0056] The first heat conversion layer 71 is prepared with a halftone mask (HTM mask) to have a protrusion 711, ensuring that the heating temperature is slightly higher than the room temperature and lower than 40° C. during the wave absorption heat conversion. The first heat conversion layer 71 is a composite wave absorbing material, which generates heat after wave absorption, so that the evaporation rate of the solution in the middle area is increased, ensuring that the temperature difference between the middle area and the edge area can compensate for the evaporation rate advantage of the solvent A in the edge area, and the evaporation rate of the solvent A tends to be consistent, so as to achieve uniform deposition of the solute B.

[0057] The first heat conversion layer 71 , for example, includes a wave-absorbing material composite of carbon nanotubes and reduced graphene oxide, which has low density, strong conductivity, strong absorption, wide absorption band, etc., and can achieve extremely strong dielectric loss capability within the frequency range of 10 GHz–26.5 GHz, thereby ensuring that the driving backplane 1 can drive the first electrode 2 through the first heat conversion layer 71 .

[0058] Here, it should be noted that the content of carbon nanotubes and the thickness of the composite absorbing material will affect its absorbing ability, and the maximum thickness H1 of the first heat conversion layer 71 and the protrusion 711 as a whole can be, for example, 2000 angstroms to 4000 angstroms. In actual application, the absorbing ability affects the evaporation rate of the solvent A, so the content of carbon nanotubes and the relationship between the thickness of the first heat conversion layer 71 and the protrusion 711 are subject to actual conditions.

[0059] The display panel provided in this embodiment has a protrusion 711 on its first heat conversion layer 71, and the local structure is adjusted so that the protrusion 711 directly contacts the middle area. The protrusion 711 absorbs waves and generates heat, so that the evaporation rate of the solution in the middle area is accelerated, compensating for the evaporation rate advantage of the solvent A in the edge area. The evaporation rate of the solvent A tends to be consistent, thereby achieving uniform deposition of the solute B.

[0060] Third embodiment

[0061] Figure 4 A schematic structural diagram of a display panel provided in an embodiment of the present application is shown.

[0062] The second embodiment of the present application also provides a display panel, which is similar to the display panel structure provided by the first embodiment or the second embodiment, except that the heat conversion unit 7 includes a first heat conversion layer 71 and a second heat conversion layer 72, and the second heat conversion layer 72 is sandwiched between the first electrode 2 and the first heat conversion layer 71.

[0063] An avoidance through hole 721 is provided in the middle area corresponding to the second heat conversion layer 72 and the first electrode 2, and the protrusion 711 passes through the avoidance through hole 721 and abuts against the first electrode 2, wherein after the heat conversion unit 7 is irradiated by the laser, the heat conversion efficiency of the first heat conversion layer 71 is greater than the heat conversion efficiency of the second heat conversion layer 72, so that the heating temperature of the first heat conversion layer 71 is higher than the heating temperature of the second heat conversion layer 72.

[0064] The depth of the avoidance through hole 721 is consistent with the thickness of the second heat conversion layer 72 to ensure the flatness of the same film layer structure. The gap between the edge of the orthographic projection of the first electrode 2 on the driving back plate 1 and the edge of the orthographic projection of the first heat conversion layer 71 on the driving back plate 1 can be, for example, 2um-5um, and the second heat conversion layer 72 is flush with the side of the first heat conversion layer 71 to ensure that the heat conversion unit 7 can completely wrap the cross section of the first electrode 2.

[0065] In this embodiment, the second heat conversion layer 72 includes a composite wave absorbing material of carbon nanotubes and a metal matrix, and the metal matrix is, for example, carbonyl iron, Fe (iron) Co (cobalt) alloy, etc. The second heat conversion layer 72 has a large density, good electrical conductivity, and can have a strong absorption capacity in the frequency range of 2 GHz-18 GHz.

[0066] Here, it should be noted that the content of nanotubes and the type and morphology of the metal matrix will affect the wave absorption capacity of the composite material. The overall thickness H2 of the first heat conversion layer 71 and the second heat conversion layer 72 can also be, for example, 2000 angstroms to 4000 angstroms. In actual use, the thickness of the first heat conversion layer 71 and the second heat conversion layer 72 needs to be determined based on factors such as the wave absorption capacity and the heating rate, and the specific thickness shall be subject to the actual situation.

[0067] In this embodiment, the insulating unit 8 fills and isolates two adjacent first heat conversion layers 71 and two adjacent second heat conversion layers 72 , and supports the pixel defining layer 3 .

[0068] like Figure 5 As shown, Figure 5 A schematic diagram of solute solidification is shown. The first heat conversion layer 71 and the second heat conversion layer 72 both include two or more absorbing material layers. Since the formation of the "coffee ring" is based on the fact that the evaporation rate of the edge region is greater than the evaporation rate of the middle region when the solvent A evaporates. Therefore, the display panel provided in this embodiment uses the first heat conversion layer 71 and the second heat conversion layer 72 in combination. The absorbing heat conversion capacity of the first heat conversion layer 71 is greater than that of the second heat conversion layer 72, so that the absorbing heat conversion capacity of the edge region and the middle region can be smoothly transitioned, avoiding a sudden drop in temperature that affects the evaporation effect, and ensuring uniform deposition of solute B.

[0069] A first heat conversion layer 71 having a trapezoidal convex structure (i.e., the protrusion 711) is prepared using an HTM mask, and a second heat conversion layer 72 is deposited on the edge regions on both sides to ensure that during wave absorption heat conversion, the heating temperatures of the first heat conversion layer 71 and the second heat conversion layer 72 are both lower than 85°C, and the temperature difference between the first heat conversion layer 71 located in the middle region and the second heat conversion layer 72 located in the edge region can compensate for the evaporation rate advantage of the solvent A located in the edge region, so that the evaporation rate of the solvent A tends to be consistent, thereby ensuring uniform deposition of the solute B.

[0070] The display panel provided by the present application prepares a single-layer film structure (i.e., the first heat conversion layer) or a multi-layer film structure (i.e., the first heat conversion layer and the second heat conversion layer) of a specific shape with a composite material having different wave absorption performance, and places it under the first electrode. When the light-emitting functional layer is prepared by inkjet printing, it is irradiated with a laser. Since the wave absorption performance of the first heat conversion layer and the second heat conversion layer are different, the heat generated is different, thereby intervening the overall evaporation rate of the solvent, avoiding the "coffee ring" problem, effectively improving the uniformity of the film quality of the light-emitting functional layer, and improving the light-emitting power and display life of the display area. When the display panel is displaying, its heat conversion unit is in direct contact with the first electrode. Since it has good conductivity, it can reduce the impedance of the first electrode, reduce current loss, improve the hole injection capacity of the hole injection layer, and improve the light-emitting efficiency.

[0071] Fourth embodiment

[0072] Figure 6 A flow chart of a method for preparing a display panel provided in an embodiment of the present application is shown.

[0073] The present application provides a method for manufacturing a display panel, comprising:

[0074] S100, providing a drive backplane.

[0075] In this step, a driving backplane is provided. The driving backplane is, for example, a transistor circuit layer capable of controlling current.

[0076] S110 , depositing a plurality of heat conversion units on the driving backplane.

[0077] In this step, a plurality of heat conversion units are deposited on the driving backplane by using photolithography technology. The plurality of heat conversion units are arranged in an array, and two adjacent heat conversion units are arranged with a gap to avoid short circuit.

[0078] Some examples include Figure 3 As shown, the heat conversion unit 7 includes, for example, a first heat conversion layer 71, which is connected to the driving back plate 1, and a protrusion 711 is provided on the side of the first heat conversion layer 71 away from the driving back plate 1. Different morphologies can achieve different wave-absorbing heat conversion capabilities.

[0079] In other examples, such as Figure 4 As shown, the heat conversion unit 7 includes, for example, a first heat conversion layer 71 and a second heat conversion layer 72 which are stacked, and the first heat conversion layer 71 is connected to the driving back plate 1. The second heat conversion layer 72 is provided with an avoidance through hole 721, and the protrusion 711 is penetrated with the avoidance through hole 721, and the second heat conversion layer 72 is flush with the protrusion 711.

[0080] The first heat conversion layer 71 and the second heat conversion layer 72 are used in combination. The wave-absorbing heat conversion capacity of the first heat conversion layer 71 is greater than that of the second heat conversion layer 72, so that the wave-absorbing heat conversion capacity of the edge area and the middle area can be smoothly transitioned to avoid a sudden drop in temperature and affect the evaporation effect.

[0081] S120, depositing an insulating unit between two adjacent heat conversion units.

[0082] In this step, an insulating unit is deposited between two adjacent heat conversion units, and the insulating unit is connected to the driving backplane to separate the heat conversion units to avoid short circuit.

[0083] S130 , depositing a plurality of first electrodes on the plurality of heat conversion units.

[0084] In this step, a plurality of first electrodes are deposited on the plurality of heat conversion units by using photolithography technology, so that the first electrodes and the heat conversion units are correspondingly connected. The first electrodes are, for example, anodes.

[0085] The orthographic projection area of ​​the conversion unit on the driving back plate is larger than the orthographic projection area of ​​the first electrode on the driving back plate, so as to ensure that the heat conversion unit can wrap the cross section of the first electrode.

[0086] S140 , depositing a pixel defining layer on the plurality of first electrodes.

[0087] In this step, a pixel defining layer is deposited on the plurality of first electrodes, and the pixel defining layer is connected to the driving backplane. Using photolithography technology, a plurality of pixel openings are formed in the pixel defining layer, so that the pixel openings can expose at least part of the first electrodes.

[0088] S150, performing laser irradiation from a side of the driving back plate away from the first electrode.

[0089] In this step, the heat conversion unit has a middle area corresponding to the first electrode and an edge area surrounding the middle area. Laser irradiation is performed from the side of the driving back plate away from the first electrode. The heat conversion unit performs wave absorption heat conversion to generate heat, so that the heating temperature of the middle area is greater than the heating temperature of the edge area.

[0090] S160, spraying a solvent into a plurality of pixel openings to print a light-emitting functional layer.

[0091] In this step, an inkjet printing method is used to spray a solvent into a plurality of pixel openings to print the light-emitting functional layer.

[0092] The light-emitting functional layer includes a plurality of light-emitting units, which are formed in the pixel openings. The pixel defining layer forms an insulating partition on the driving backplane to separate two adjacent light-emitting units to avoid crosstalk. The heating temperature of the middle area is greater than the heating temperature of the edge area, so that the evaporation rate of the solvent in the middle area and the edge area tends to be consistent, ensuring uniform deposition of the solute in the light-emitting function.

[0093] The heating temperatures of the middle area and the edge area of ​​the heat conversion unit are both lower than 85° C., which can improve the deposition effect of the light-emitting functional layer without destroying the film structure of the light-emitting function.

[0094] S170, depositing a second electrode on the light-emitting functional layer.

[0095] In this step, a second electrode is deposited on the light-emitting functional layer, and the second electrode covers the pixel defining layer and the light-emitting functional layer. The second electrode is, for example, a cathode. When the driving backplane is working, under a certain voltage drive, electrons and holes move from the second electrode and the first electrode to the light-emitting functional layer, respectively, so that it emits visible light.

[0096] S180, depositing a packaging layer on the second electrode.

[0097] In this step, a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer are sequentially deposited on the second electrode, and the first inorganic encapsulation layer is connected to the second electrode. The first inorganic encapsulation layer can prevent the light-emitting unit formed by the organic light-emitting material from being invading by water and oxygen and thus failing, and the second inorganic encapsulation layer has the functions of stress release and flattening.

[0098] The preparation method of the display panel provided in this embodiment uses a thermal conversion unit to change the temperature of the inkjet area when preparing the light-emitting functional layer by inkjet printing, thereby intervening in the overall evaporation rate of the solvent and effectively improving the film quality of the light-emitting functional layer. The thermal conversion unit has good conductivity, which can reduce current loss, enhance the hole injection capacity of the hole injection layer, and enhance the light-emitting efficiency.

[0099] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0100] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0101] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A display panel, comprising a driving backplane, a plurality of first electrodes arrayed on the driving backplane, a pixel defining layer and a light-emitting function layer, wherein the pixel defining layer comprises a plurality of pixel openings, wherein the pixel openings expose at least a portion of the first electrodes, and the light-emitting function layer comprises a plurality of light-emitting units, wherein the light-emitting units are correspondingly arranged in the pixel openings, wherein: The display panel includes a plurality of heat conversion units, the heat conversion units are sandwiched between the first electrode and the driving backplane, and the heat conversion units are electrically connected to the first electrode, and the heat conversion units have a middle area corresponding to the first electrode and an edge area surrounding the middle area; When laser irradiation is performed from a side of the driving backplane away from the first electrode to print the light-emitting functional layer, the heating temperature of the edge region after absorbing the laser is lower than the heating temperature of the middle region after absorbing the laser.

2. The display panel according to claim 1, characterized in that: The middle area of ​​the heat conversion unit is made of a first absorbing material, and the edge area is made of a second absorbing material. After the heat conversion unit is irradiated by the laser, the heat conversion efficiency of the first absorbing material is greater than the heat conversion efficiency of the second absorbing material.

3. The display panel according to claim 1, characterized in that: The heat conversion unit includes a first heat conversion layer, the first heat conversion layer is connected to the driving back plate, and a protrusion is provided in the middle area of ​​the first heat conversion layer corresponding to the first electrode, and the protrusion abuts against the first electrode.

4. The display panel according to claim 3, characterized in that: The heat conversion unit includes a second heat conversion layer, and the second heat conversion layer is sandwiched between the first electrode and the first heat conversion layer; An avoidance through hole is provided in the middle area corresponding to the second heat conversion layer and the first electrode, and the protrusion passes through the avoidance through hole and abuts against the first electrode, wherein after the heat conversion unit is irradiated by the laser, the heat conversion efficiency of the first heat conversion layer is greater than the heat conversion efficiency of the second heat conversion layer.

5. The display panel according to claim 4, characterized in that: The first heat conversion layer comprises a wave absorbing material composited with carbon nanotubes and reduced graphene oxide; the second heat conversion layer comprises a wave absorbing material composited with carbon nanotubes and a metal matrix.

6. The display panel according to claim 1, characterized in that: The orthographic projection area of ​​the heat conversion unit on the driving backplane is larger than the orthographic projection area of ​​the first electrode on the driving backplane.

7. The display panel according to claim 1, characterized in that: It comprises a plurality of insulating units, wherein the insulating unit is arranged between two adjacent heat conversion units.

8. A method for preparing a display panel, characterized in that: include: Provide drive backplane; Depositing a plurality of heat conversion units on the driving backplane; Depositing a plurality of first electrodes on the plurality of heat conversion units; Depositing a pixel defining layer on the plurality of first electrodes, the pixel defining layer comprising a plurality of pixel openings, the pixel openings exposing at least a portion of the first electrodes; Performing laser irradiation from a side of the driving back plate away from the first electrode; A solvent is sprayed in the plurality of pixel openings to print a light-emitting functional layer, wherein the light-emitting functional layer includes a plurality of light-emitting units, and the light-emitting units are formed in the pixel openings; wherein the heat conversion unit has a middle area corresponding to the first electrode and an edge area surrounding the middle area, and a heat generation temperature of the edge area after absorbing the laser is lower than a heat generation temperature of the middle area after absorbing the laser, so that the evaporation rates of the solvent in the middle area and the edge area tend to be consistent.

9. The method for preparing a display panel according to claim 8, characterized in that: Before depositing a plurality of first electrodes on the plurality of heat conversion units, the method further comprises: An insulating unit is deposited between two adjacent heat conversion units, and the insulating unit is connected to the driving backplane.

10. The method for preparing a display panel according to claim 8, characterized in that: The heating temperature of the middle area and the heating temperature of the edge area of ​​the heat conversion unit are both lower than 85°C.

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