Photosensitive composition, pixel definition layer and display panel

Abstract

The embodiment of the invention provides a photosensitive composition, a pixel definition layer and a display panel. The pixel definition layer includes a polymer and a plurality of pigments. A plurality of pigments are dispersed in the polymer and include a first pigment. The particle size of the first pigment is less than or equal to 90 nanometers. Thus, the first pigment can reduce the roughness of the surface of the pixel definition layer, the problem of short circuit of the light-emitting device due to too large surface roughness of the pixel definition layer is improved, and the problem of dark spots of the display panel during display due to short circuit is further improved.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a photosensitive composition, a pixel definition layer and a display panel. Background Art

[0002] As people's requirements for the display effects of electronic devices become more and more diverse, organic light-emitting display panels have become the main research and development direction in the display field due to their self-luminescence, wide viewing angle, wide color gamut, high contrast, thin, foldable, bendable, thin and easy to carry and other characteristics. At present, organic light-emitting display panels are mostly based on organic light-emitting diode (OLED) technology. However, organic light-emitting display panels will have dark spot problems during the display process, that is, the organic light-emitting diodes will not emit light. If the proportion of dark spots is too high, it will reduce the display effect of the display panel. Summary of the invention

[0003] The embodiments of the present application provide a photosensitive composition, a pixel definition layer and a display panel to improve the problem of dark spots appearing when the display panel displays.

[0004] In a first aspect, an embodiment of the present application provides a pixel definition layer. The pixel definition layer includes a polymer and a plurality of pigments. The plurality of pigments are dispersed in the polymer and include a first pigment. The particle size of the first pigment is less than or equal to 90 nanometers.

[0005] In a second aspect, an embodiment of the present application further provides a display panel, which includes the above-mentioned pixel definition layer.

[0006] In a third aspect, the present application also provides a photosensitive composition, which includes a photocurable monomer, a photoinitiator, and a plurality of pigments, wherein the plurality of pigments includes a first pigment, wherein the particle size of the first pigment is less than or equal to 90 nanometers.

[0007] In the photosensitive composition, pixel definition layer and display panel of some embodiments of the present application, the first pigment can reduce the surface roughness of the pixel definition layer, improve the problem of short circuit of the light-emitting device due to excessive surface roughness of the pixel definition layer, and further improve the problem of dark spots appearing on the display panel due to short circuit during display. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A schematic diagram of the structure of a display panel provided in an embodiment of the present application;

[0009] Figures 2 to 5 The SEM test images of the surface of the pixel definition layer in Examples 6 to 7, Example 10 and Comparative Example 2;

[0010] Figures 6 to 8The SEM test images of the cathode layer of the display panel in Example 12 to Example 13 and Comparative Example 3;

[0011] Figures 9 to 11 TEM test images of the surface of the pixel definition layer in the display panel in Examples 12 to 13 and Comparative Example 3.

[0012] The reference numerals are as follows:

[0013] 100. Display panel;

[0014] 11. Substrate;

[0015] 21. Driving circuit layer;

[0016] 31. Light-emitting device layer;

[0017] 310, pixel definition layer; 311, pigment; 311A, first pigment; 312, dam; 313, pixel opening;

[0018] 320, anode layer;

[0019] 330, cathode layer;

[0020] 340, organic light-emitting layer; R, red light organic light-emitting layer; G, green light organic light-emitting layer; B, blue light organic light-emitting layer;

[0021] 41. Thin film encapsulation layer;

[0022] 51, color filter layer; 511, black matrix layer; 511A, light-transmitting opening; 512, first filter unit; 513, second filter unit; 514, third filter unit. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0024] See also Figure 1 As shown, an embodiment of the present application provides a display panel 100. The display panel 100 includes a substrate 11, a driving circuit layer 21 and a light emitting device layer 31. The driving circuit layer 21 is located between the light emitting device layer 31 and the substrate 11.

[0025] The substrate 11 may include at least one of a hard substrate and a flexible substrate. For example, the substrate 11 includes a hard substrate such as a glass substrate.

[0026] The driving circuit layer 21 includes a plurality of pixel driving circuits. The pixel driving circuits include driving devices, which include but are not limited to thin film transistors and the like.

[0027] The light-emitting device layer 31 includes a pixel definition layer 310, an anode layer 320, a cathode layer 330, and an organic light-emitting layer 340. The anode layer 320 is located on the driving circuit layer 21. The anode layer 320 includes a plurality of spaced anodes. The pixel definition layer 310 is located on the anode layer 320 and the driving circuit layer 21, and includes a pixel opening 313 and a pixel dam 312. The pixel dam 312 is arranged around the pixel opening 313. The pixel opening 313 exposes part of the anode. In some embodiments, a plurality of organic light-emitting layers 340 emitting a plurality of different colors of light can be respectively located in a plurality of pixel openings 313, for example, a red light organic light-emitting layer R, a green light organic light-emitting layer G, and a blue light organic light-emitting layer B can be respectively located in a plurality of pixel openings 313. In other embodiments, an organic light emitting layer 340 may be located in the pixel opening 313 and on the pixel dam 312 outside the pixel opening 313. For example, a white light organic light emitting layer is located in a plurality of pixel openings 313 and on the pixel dam 312 outside the pixel opening 313. The cathode layer 330 covers the organic light emitting layer 340 and the pixel dam 312. The anode, the cathode layer 330, and the organic light emitting layer 340 located between the anode and the cathode layer 330 constitute a light emitting device.

[0028] In some embodiments, the thickness of the pixel definition layer 310 is 0.5 micrometers to 3 micrometers, so as to ensure that the pixel dam 312 of the pixel definition layer 310 can play a role in preventing crosstalk and reduce its manufacturing difficulty.

[0029] In some embodiments, see Figure 1 As shown, the pixel definition layer 310 includes a polymer and a plurality of pigments 311 so that the pixel definition layer 310 has a specific color.

[0030] A plurality of pigments 311 are dispersed in the polymer and include a first pigment 311A. The particle size of the first pigment 311A ​​is less than or equal to 90 nanometers. In this way, the problem of the large surface roughness of the pixel definition layer 310 caused by the large particle size of the first pigment 311A ​​is improved, so as to improve the problem of short circuit of the light emitting device due to the large surface roughness of the pixel definition layer 310, and further improve the problem of dark spots appearing due to the short circuit when the display panel 100 is displayed.

[0031] In some embodiments, the particle size of the first pigment 311A ​​is greater than or equal to 60 nanometers, so as to improve the problem of the first pigment 311A ​​agglomerating due to the small particle size of the first pigment 311A, thereby reducing the problem of the surface roughness of the pixel definition layer 310 being too large due to the aggregation of the first pigment 311A. The problem of the light emitting device short-circuiting due to the excessive surface roughness of the pixel definition layer 310 is improved, and the problem of dark spots appearing when the display panel 100 is displayed is further improved.

[0032] In some embodiments, the particle size of the first pigment 311A ​​is greater than or equal to 65 nanometers and less than or equal to 85 nanometers. In this way, the particle size of the first pigment 311A ​​is controlled within a suitable range, which improves the problem that the particle size of the first pigment 311A ​​is too large, directly leading to excessive surface roughness of the pixel definition layer 310, and also improves the problem that the particle size of the first pigment 311A ​​is too small, which leads to easy aggregation and thus excessive surface roughness of the pixel definition layer 310.

[0033] Optionally, the particle size of the first pigment 311A ​​may be 60 nanometers to 75 nanometers, 70 nanometers to 85 nanometers, or 80 nanometers to 90 nanometers.

[0034] It is understandable that the particle size of each of the plurality of first pigments 311A ​​can be any value between 60 nanometers and 90 nanometers, for example, 60 nanometers, 65 nanometers, 70 nanometers, 75 nanometers, 80 nanometers, 85 nanometers or 90 nanometers.

[0035] In some embodiments, when the particle size of the first pigment 311A ​​is less than or equal to 90 nanometers, the percentage of the number of the first pigment 311A ​​in the plurality of pigments 311 is greater than or equal to 40%. In this way, the percentage of the number of the first pigment 311A ​​in the plurality of pigments 311 is ensured to be large, further improving the problem of short circuit of the light-emitting device due to excessive surface roughness of the pixel definition layer 310.

[0036] It should be noted that the statistical method for calculating the percentage of the number of the first pigment 311A ​​in the multiple pigments 311 includes but is not limited to: 1) selecting at least three different areas in the pixel definition layer 310, each area having the same number of pigments 311, for example, 50; 2) counting the number of first pigments 311A ​​in each area; 3) counting the sum of the numbers of first pigments 311A ​​in at least three areas, and dividing the total number of first pigments 311A ​​by the total number of pigments 311 in the three areas to obtain the percentage of the number of the first pigment 311A ​​in the multiple pigments 311.

[0037] In some embodiments, when the particle size of the first pigment 311A ​​is less than or equal to 90 nanometers, the number percentage of the first pigment 311A ​​in the plurality of pigments 311 is greater than or equal to 50%. In this way, the number percentage of the first pigment 311A ​​in the plurality of pigments 311 is further increased, and the number percentage of the pigment 311 with a size greater than 90 nanometers is reduced, further improving the problem of short circuit of the light-emitting device due to excessive surface roughness of the pixel definition layer 310.

[0038] Optionally, when the particle size of the first pigment 311A ​​is less than or equal to 90 nanometers, the number percentage of the first pigment 311A ​​in the multiple pigments 311 is greater than or equal to 55%, or the number percentage of the first pigment 311A ​​in the multiple pigments 311 is greater than or equal to 60%, or the number percentage of the first pigment 311A ​​in the multiple pigments 311 is greater than or equal to 65%, or the number percentage of the first pigment 311A ​​in the multiple pigments 311 is greater than or equal to 70%.

[0039] In some embodiments, the number percentage of the first pigment 311A ​​in the plurality of pigments 311 is less than or equal to 99%, thereby reducing the difficulty of forming the plurality of pigments 311 in the process.

[0040] In some embodiments, the percentage of the first pigment 311A ​​with a particle size of 60 nm to 90 nm in the plurality of pigments 311 is greater than or equal to 50%. Thus, the first pigment 311A ​​with a suitable particle size is controlled to have a larger percentage, thereby reducing the surface roughness of the pixel definition layer 310.

[0041] Optionally, the percentage of the number of first pigments 311A ​​having a particle size of 60 nanometers to 90 nanometers in the plurality of pigments 311 is greater than or equal to 60%, 65%, 70% or 75%.

[0042] In some embodiments, the peak of the number particle size distribution of the plurality of pigments 311 corresponds to a particle size of 60 nm to 90 nm. Thus, the number of pigments with a particle size of 60 nm to 90 nm accounts for a larger proportion, thereby reducing the surface roughness of the pixel definition layer 310 .

[0043] Optionally, the particle size corresponding to the peak of the number particle size distribution of the plurality of pigments 311 is 65 nanometers to 88 nanometers or 75 nanometers to 85 nanometers.

[0044] In some embodiments, the plurality of pigments 311 further include a second pigment (not shown in the figure), and the particle size of the second pigment is larger than the particle size of the first pigment 311A. The particle size of the second pigment is larger than 90 nanometers. The number percentage of the second pigment in the plurality of pigments 311 is less than or equal to 5%. In this way, the number percentage of the second pigment is reduced, and the risk of the second pigment with a larger particle size causing a larger surface roughness of the pixel definition layer 310 is reduced.

[0045] In some embodiments, among the plurality of pigments 311, the number of pigments 311 with a particle size less than 60 nanometers accounts for less than the number of first pigments 311A ​​with a particle size of 60 nanometers to 90 nanometers. In this way, the number of first pigments 311A ​​with a particle size of 60 nanometers to 90 nanometers accounts for a larger proportion, thereby reducing the surface roughness of the pixel definition layer 310.

[0046] In some embodiments, the percentage of the second pigment in the plurality of pigments 311 is less than the percentage of the pigments 311 with a particle size less than 60 nanometers. Reducing the percentage of the second pigment reduces the risk of the second pigment with a larger particle size causing greater surface roughness of the pixel definition layer 310.

[0047] In some embodiments, the number of pigments 311 with a particle size less than 60 nanometers may account for less than or equal to 10%. In this way, the risk of aggregation of pigments 311 with a particle size less than 60 nanometers is reduced, the dispersion uniformity of the pigments 311 in the polymer is improved, the uniformity of the reflectivity of light at different positions of the pixel definition layer 310 is improved, and the surface roughness of the pixel definition layer 310 is reduced.

[0048] Optionally, among the plurality of pigments 311 , the number of pigments 311 having a particle size less than 60 nanometers may account for less than or equal to 8%, 5% or 3%.

[0049] In some embodiments, the optical density of the pixel definition layer 310 with a thickness of 1 micron to visible light is less than or equal to 1.2. In this way, the problem of too high a mass percentage of the pigment 311 in the pixel definition layer 310 leading to a large roughness of the pixel definition layer 310 is improved, thereby improving the problem of a large proportion of dark spots due to the large roughness.

[0050] It should be noted that optical density (OD) is a measure used to describe the light absorption capacity of a material. It indicates the degree to which light is absorbed when passing through a material and is commonly used in the fields of optics and spectroscopy. The definition of optical density is related to transmittance (T), which is the ratio of the intensity of light passing through a material to the intensity of incident light. For the pixel definition layer 310, the greater the optical density, the greater the mass percentage of the pigment 311 in the pixel definition layer 310.

[0051] In some embodiments, the optical density of the pixel definition layer 310 with a thickness of 1 micron to visible light is greater than or equal to 0.4. In this way, the problem of too low mass percentage of the pigment 311 in the pixel definition layer 310 resulting in low reflectivity of the pixel definition layer 310 to light is improved, thereby improving the display contrast of the display panel.

[0052] Optionally, the pixel definition layer 310 having a thickness of 1 micrometer has an optical density of 0.5-1.15, 0.6-1.1, 0.7-1, 0.8-1.2 or 0.4-1 to visible light.

[0053] In some embodiments, the root mean square roughness of the surface of the pixel definition layer 310 is less than or equal to 6 nm. In this way, the surface roughness of the pixel definition layer 310 is small, so as to reduce the risk that the thin light-emitting layer cannot cover the surface of the pixel definition layer 310, thereby improving the problem of dark spots in pixels caused by local short circuits of light-emitting devices.

[0054] In some embodiments, the root mean square roughness of the surface of the pixel definition layer 310 is less than or equal to 5.5 nm, or less than or equal to 4.8 nm, or less than or equal to 4 nm.

[0055] It should be noted that the instrument for measuring the root mean square roughness of the surface of the pixel definition layer 310 includes but is not limited to an atomic force microscope.

[0056] In some embodiments, the plurality of pigments 311 include a plurality of black pigments, so that the pixel definition layer 310 is black, the reflectivity of the pixel definition layer 310 to light is reduced, and the display contrast of the display panel 100 is improved.

[0057] In some embodiments, when the plurality of pigments 311 include a plurality of black pigments, the plurality of pigments 311 may include an organic black pigment. The organic black pigment includes at least one of carbon black, phthalocyanine black, azo black, quinone pigments, and indoline black. Quinone pigments include but are not limited to benzofuranone black. Phthalocyanine black includes but is not limited to at least one of lactam black and perylene black. Azo black includes but is not limited to aniline black.

[0058] In other embodiments, when the plurality of pigments 311 include a plurality of black pigments, the plurality of pigments 311 may include inorganic black pigments.

[0059] In other embodiments, the plurality of pigments 311 may also include other pigments besides black pigment, such as one or more of red pigment, green pigment, blue pigment and yellow pigment.

[0060] In some embodiments, the ratio of the mass of the plurality of pigments 311 to the mass of the polymer is (1-5):(6-13). In this way, a suitable mass ratio between the pigments 311 and the polymer is ensured, and the roughness of the surface of the pixel definition layer 310 is reduced while ensuring that the pixel definition layer 310 has a low reflectivity to light. In addition, the polymer is ensured to provide sufficient heat resistance to improve its stability under high temperature processes.

[0061] Optionally, the ratio of the mass of the plurality of pigments 311 to the mass of the polymer is (2-4):(6-13).

[0062] In some embodiments, the polymer is obtained by initiating the photocurable monomer with a photoinitiator. Before the photocurable monomer is cured, the initial pixel definition layer can be patterned with a developer to achieve patterning of the initial pixel definition layer 310. After patterning, the photocurable monomer is cured to improve the mechanical properties and high temperature resistance of the pixel definition layer 310.

[0063] In some embodiments, the photocurable monomer includes a polymerizable monomer, and the polymerizable monomer may include a resin having an alkali-soluble group. The alkali-soluble group includes a carboxyl group and / or a hydroxyl group. The resin having an alkali-soluble group includes at least one of an alkaline cardo resin, an alkali-soluble acrylic resin, and an alkali-soluble polybenzoxazole resin. In this way, patterning of the initial pixel definition layer including the resin having an alkali-soluble group can be achieved using an alkaline developer.

[0064] In some embodiments, the photocurable monomer further comprises a multifunctional monomer, which plays a role in cross-linking the polymerizable monomers during the photocuring process, thereby improving the high temperature resistance of the polymer.

[0065] In some embodiments, the multifunctional monomer includes two or more vinyl unsaturated double bonds. In some embodiments, the multifunctional monomer includes one or more of ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, pentaerythritol triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, bisphenol A epoxy acrylate, ethylene glycol monomethyl ether acrylate, and trimethylolpropane triacrylate.

[0066] In some embodiments, the mass ratio of the polymerizable monomer to the multifunctional monomer is (5-10):(1-3). In this way, the pixel definition layer 310 is ensured to have suitable mechanical properties and high temperature resistance.

[0067] Optionally, the mass ratio between the polymerizable monomer and the multifunctional monomer is (6-8):(1-3).

[0068] In some embodiments, the display panel 100 may further include a thin film encapsulation layer. The thin film encapsulation layer covers the light emitting device layer 31. The thin film encapsulation layer blocks water vapor and oxygen, etc., and reduces the risk of water vapor and oxygen, etc. penetrating into the light emitting device layer 31 and causing the light emitting device layer 31 to fail.

[0069] In some embodiments, the thin film encapsulation layer includes two inorganic thin film encapsulation layers and an organic thin film encapsulation layer located between the two inorganic thin film encapsulation layers. The inorganic thin film encapsulation layer includes at least one of silicon oxide, silicon nitride and silicon oxynitride. The organic thin film encapsulation layer includes at least one of polyacrylate and epoxy resin.

[0070] In some embodiments, the display panel 100 may further include a color filter layer. The color filter layer is located on the side of the light-emitting device layer 31 away from the substrate 11. The color filter layer includes a black matrix layer, a first filter unit, a second filter unit and a third filter unit. The colors of the first filter unit, the second filter unit and the third filter unit are different from each other. The black matrix layer includes a plurality of light-transmitting openings. The first filter unit to the third filter unit are all located in the plurality of light-transmitting openings. The plurality of light-transmitting openings overlap with the plurality of pixel openings 313, respectively, to ensure that the light emitted by the organic light-emitting layer 340 is emitted from the plurality of light-transmitting openings. In this way, the color filter layer not only filters the light emitted by the light-emitting device layer 31, improves the display effect of the display panel 100, but also reduces the reflectivity of the light incident from the outside to the display panel 100, reduces the interference of the ambient light on the display panel 100, and improves the display contrast. In addition, compared with the polarizer, the thickness of the color filter layer is thinner, which can reduce the overall thickness of the display device.

[0071] In other embodiments, the display panel 100 may also include a circular polarizer. The circular polarizer is located on the side of the light-emitting device layer 31 away from the substrate 11. In this way, the circular polarizer is used to reduce the reflectivity of light incident from the outside to the display panel 100, reduce the interference of ambient light on the display panel 100, and improve the display contrast.

[0072] In some embodiments, the opening area of ​​the light-transmitting opening is larger than the opening area of ​​the pixel opening 313, so that the light emitted by the organic light-emitting layer 340 is emitted from the plurality of light-transmitting openings. In addition, since the black pigment colors the first pixel definition layer 310 black, the first pixel definition layer 310 has a low reflectivity to light, and the light incident from the outside to the pixel definition layer 310 is less reflected, thereby improving the display contrast.

[0073] In some embodiments, the display panel 100 may further include a touch layer. The touch layer may be located between the color filter layer and the light emitting device layer 31. The touch layer may include touch electrodes, and the touch electrodes may include self-capacitive touch electrodes or mutual-capacitive touch electrodes.

[0074] In addition, the embodiment of the present application also provides a photosensitive composition, and the above-mentioned pixel definition layer 310 is prepared from the photosensitive composition. The photosensitive composition includes a photocurable monomer, a photoinitiator and a plurality of pigments 311, and the plurality of pigments 311 include a first pigment 311A. The particle size of the first pigment 311A ​​is less than or equal to 90 nanometers. In this way, the pixel definition layer 310 prepared from the photosensitive composition includes the first pigment 311A, which reduces the roughness of the surface of the pixel definition layer 310, improves the problem of short circuit of the light-emitting device due to the excessive surface roughness of the pixel definition layer 310, and further improves the problem of dark spots due to short circuit when the display panel 100 is displayed.

[0075] It should be noted that the design of the plurality of pigments 311 may be the same as the design of the plurality of pigments 311 in the above-mentioned pixel definition layer 310 , which will not be described in detail here.

[0076] In some embodiments, the plurality of pigments 311 include a plurality of black pigments, so that the organic polymer layer prepared from the photosensitive composition has low reflectivity to visible light.

[0077] In some embodiments, the photosensitive composition includes, by mass percentage, 1% to 5% pigment 311; 5% to 10% polymerizable monomer; 1% to 3% multifunctional monomer; 1% to 3% photoinitiator; and the balance is solvent. In this way, the yield of the initial pixel definition layer 310 during the development process is improved, and the high temperature resistance of the patterned initial pixel definition layer after curing is ensured.

[0078] In some embodiments, the photosensitive composition includes, by mass percentage, 2% to 4% pigment 311; 6% to 8% polymerizable monomer; 1% to 3% multifunctional monomer; 1% to 3% photoinitiator; and the balance is solvent. In this way, not only the yield of the initial pixel definition layer during the development process is improved, but also the high temperature resistance and low reflectivity of the patterned initial pixel definition layer after curing are ensured.

[0079] In some embodiments, the polymerizable monomer may include a resin having an alkali soluble group. The alkali soluble group includes a carboxyl group and / or a hydroxyl group. The resin having an alkali soluble group includes at least one of an alkaline cardo resin, an alkali soluble acrylic resin, and an alkali soluble polybenzoxazole resin. In this way, the patterning of the initial pixel definition layer 310 including the resin having an alkali soluble group can be achieved using an alkaline developer.

[0080] In some embodiments, the multifunctional monomer may include two or more vinyl unsaturated double bonds. In some embodiments, the multifunctional monomer includes one or more of ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, pentaerythritol triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, bisphenol A epoxy acrylate, ethylene glycol monomethyl ether acrylate, and trimethylolpropane triacrylate.

[0081] In some embodiments, the photoinitiator may include, but is not limited to, an oxime ester-based photopolymerization initiator.

[0082] In some embodiments, the solvent may include at least one of an ether solvent and an ester solvent. The ester solvent includes at least one of 3-methoxy-3-methyl butyl acetate, propylene glycol methyl ether acetate, and oxybutyl acetate. The ether solvent includes but is not limited to propylene glycol methyl ether.

[0083] In some embodiments, the photosensitive composition further includes additives such as a dispersant. The mass percentage of the dispersant in the photosensitive composition is 0.01% to 1% by mass. In this way, the uniformity of the dispersion of the pigment 311 in the polymer is improved, which not only improves the problem of large roughness of the pixel definition layer 310 caused by the aggregation of the pigment 311, but also improves the uniformity of the reflectivity of the pixel definition layer 310 to light in different regions.

[0084] In some embodiments, the dispersant may include at least one of a nonionic dispersant, an anionic dispersant, and a cationic dispersant. The nonionic dispersant may include, but is not limited to, at least one of polyglycol and its ester, carboxylate, and polyoxyalkylene. The anionic dispersant may include at least one of a sulfonate, a sulfonate, and a carboxylate.

[0085] In summary, in the photosensitive composition, pixel definition layer and display panel of some embodiments of the present application, the pixel definition layer includes a polymer and a plurality of pigments. The plurality of pigments are dispersed in the polymer and include a first pigment 311A. The particle size of the first pigment 311A ​​is less than or equal to 90 nanometers. In this way, the first pigment 311A ​​can reduce the roughness of the surface of the pixel definition layer, improve the problem of short circuit of the light-emitting device due to excessive surface roughness of the pixel definition layer, and further improve the problem of dark spots due to short circuit when the display panel is displayed.

[0086] The performance of the photosensitive composition and the pixel definition layer of the embodiment of the present application is verified in combination with specific examples and comparative examples.

[0087] The black pigment of comparative example 1 is an original black pigment (particle size greater than or equal to 120 nanometers), and the original black pigment is purchased from BASF's Irgaphor Black S0100 CF. The black pigments of Examples 1 to 5 are obtained by ball milling the original black pigment. The polymerization monomers of Examples 1 to 5 and Comparative Example 1 are alkali-soluble Cardo resins ((amine value is 0 (mg KOH / g), resin acid value is 90 (mgKOH / g)), and are purchased from ADEKA ARKLS WR-301 of ADEKA. The multifunctional monomer is tetraethylene glycol diacrylate, and is purchased from Aronix M-240 of Toa Synthetic Chemical Industry Co., Ltd. The photocuring agent is 1-(O-acetoxime), and is purchased from BASF's OXE02. The dispersant is purchased from Bick's DISPERBYK-101. The solvent is 3-methoxy-3-methylbutyl acetate, and is commercially available.

[0088] Table 1 Photosensitive compositions of Examples 1 to 5 and Comparative Example 1

[0089]

[0090]

[0091] The peak of the number particle size distribution corresponds to a particle size of 60 nm, which means that among the multiple black pigments, the number of black pigments with a particle size of 60 nm accounts for the largest proportion. The particle sizes corresponding to the peak of the number particle size distribution are 80 nm, 90 nm, and 140 nm, and so on, which will not be repeated here.

[0092] Examples 6 to 10 and Comparative Example 2

[0093] The pixel definition layers of Examples 6 to 10 and Comparative Example 2 were prepared using the formulations of Examples 1 to 5 and Comparative Example 1. The thickness of the pixel definition layers was 1 micron, and the pixel definition layers were tested as follows.

[0094] 1) Root mean square roughness test

[0095] The root mean square roughness of the surface of the pixel definition layer was tested using an atomic force microscope.

[0096] 2) Optical density test

[0097] The optical density of the pixel definition layer is tested using a D65 light source. Optical density = (lg(1 / Tr)) / Thk, where T(λ) is the transmittance of the pixel definition layer to light, and Thk is the thickness of the pixel definition layer.

[0098] 3) SEM test 1

[0099] The number of black pigments with a surface particle size greater than 200 nanometers on the pixel definition layer was observed using a scanning electron microscope.

[0100] Table 2 Examples 6 to 10 and Comparative Example 2

[0101]

[0102] Combined with Table 2 and Figures 2 to 5 It can be seen that the roughness of the pixel definition layer of Examples 6 to 10 is less than that of Comparative Example 2. Therefore, compared with the particle size of the black pigment in Comparative Example 1, the particle size corresponding to the peak of the number particle size distribution of the black pigment in the photosensitive composition of Examples 1 to 5 is 60nm to 90nm, which can reduce the number of black pigments with a surface particle size greater than 200nm in the pixel definition layer, thereby reducing the roughness of the pixel definition layer and the optical density of the pixel definition layer.

[0103] It can be seen from Example 7 and Example 9 that the greater the mass percentage of the black pigment in the photosensitive composition, the greater the optical density of the pixel definition layer.

[0104] Examples 11 to 13 and Comparative Example 3

[0105] Embodiments 11 to 13 and Comparative Example 3 all provide display panel motherboards. Each display panel motherboard includes a plurality of display panels, and the structure of each display panel is shown in 1. The pixel definition layers of the display panel motherboards in Embodiments 11 to 13 and Comparative Example 3 are prepared using the formulas of Embodiments 1 to 2, Embodiment 5 and Comparative Example 1. The display panel motherboards are tested as follows.

[0106] 4) Dark spot test:

[0107] For each of Examples 11 to 13 and Comparative Example 3, 2000 display panels on a display panel motherboard are used as a group of test samples. Each display panel is lit, and an automatic optical detection device is used to detect a certain area of ​​each display panel (for example, the certain area includes 10,000 pixels). When the number of dark pixels exceeds 1, the display panel is considered to have a dark spot. The ratio of the number of all display panels with dark spots to 2000 is the dark spot ratio.

[0108] 5) SEM Test 2

[0109] The cathode layer in the display panel was observed using a scanning electron microscope.

[0110] 6) TEM test

[0111] Transmission electron microscopy was used to observe the black pigment in the pixel definition layer of the display panel.

[0112] Table 3 Test results of display panels of Examples 11 to 13 and Comparative Example 3

[0113]

[0114] It can be seen from Table 3 that the dark spot ratio of the display panel in Examples 11 to 13 is much smaller than that in Comparative Example 3. Moreover, the particle size of the black pigment on the surface of the pixel definition layer in Examples 12 and 13 is smaller than that in Comparative Example 3. Therefore, compared with the particle size selection of the black pigment in the photosensitive composition in Comparative Example 1, the particle size selection of the black pigment in the photosensitive composition in Examples 1 to 2 and 5 can reduce the roughness of the pixel definition layer, improve the wrinkle problem of the cathode layer on the pixel definition layer, and thus significantly reduce the dark spot ratio of the display panel.

[0115] The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application. Ordinary technical personnel in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A pixel definition layer, characterized in that: include: polymer; A plurality of pigments are dispersed in the polymer and include a first pigment, wherein the particle size of the first pigment is less than or equal to 90 nanometers.

2. The pixel definition layer according to claim 1, characterized in that: The particle size of the first pigment is greater than or equal to 60 nanometers.

3. The pixel definition layer according to claim 1 or 2, characterized in that: The particle size of the first pigment is greater than or equal to 65 nanometers and less than or equal to 85 nanometers.

4. The pixel definition layer according to claim 1 or 2, characterized in that: Among the plurality of pigments, the number percentage of the first pigment is greater than or equal to 50%.

5. The pixel definition layer according to claim 1 or 2, characterized in that: The plurality of pigments further include a second pigment, the particle size of the second pigment being greater than 90 nanometers; and the number percentage of the second pigment in the plurality of pigments is less than or equal to 5%.

6. The pixel definition layer according to claim 1, characterized in that: The optical density of the pixel definition layer with a thickness of 1 micron to visible light is less than or equal to 1.

2.

7. The pixel definition layer according to claim 6, characterized in that: The optical density of the pixel definition layer with a thickness of 1 micron to visible light is greater than or equal to 0.

4.

8. The pixel definition layer according to claim 1 or 2, characterized in that: The root mean square roughness of the surface of the pixel definition layer is less than or equal to 6 nm.

9. The pixel definition layer according to claim 1, characterized in that: The plurality of pigments include a plurality of black pigments, and a ratio of the mass of the plurality of pigments to the mass of the polymer is (1-5):(6-13).

10. The pixel definition layer according to claim 1, characterized in that: The polymer is obtained from a photocurable monomer through the initiation of a photoinitiator, and the photocurable monomer includes a resin having an alkali-soluble group.

11. A display panel, characterized in that: The invention comprises the pixel definition layer according to any one of claims 1 to 10.

12. A photosensitive composition, characterized in that: include: Photocurable monomers; Photoinitiator; as well as A plurality of pigments includes a first pigment having a particle size less than or equal to 90 nanometers.

13. The photosensitive composition according to claim 12, characterized in that The particle size of the first pigment is greater than or equal to 60 nanometers.

14. The photosensitive composition according to claim 12, characterized in that Calculated by mass percentage, the photosensitive composition includes: 1% to 5% pigment; 5% to 10% polymerized monomer; 1% to 3% multifunctional monomers; 1% to 3% photoinitiator; and The balance is solvent.

15. The photosensitive composition according to claim 12 or 14, characterized in that: The plurality of pigments include a plurality of black pigments, and / or the photosensitive composition further includes a dispersant.

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