Photosensitive composition, pixel definition layer, and display panel

Abstract

A photosensitive composition, a pixel definition layer, and a display panel. The pixel definition layer comprises 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. The first pigment can reduce the surface roughness of the pixel definition layer, thereby mitigating the problem of short circuits occurring in light-emitting devices due to excessive surface roughness of the pixel definition layer, and thus mitigating the problem of dark spots occurring on the display panel during display due to short circuits.

Description

Photosensitive composition, pixel definition layer and display panel Technical Field

[0001] This application relates to the field of display technology, and more particularly to a photosensitive composition, a pixel definition layer, and a display panel. Background Technology

[0002] With increasingly demanding requirements for the display quality of electronic devices, organic light-emitting diode (OLED) panels have become a major research and development direction in the display field due to their self-emissive nature, wide viewing angle, wide color gamut, high contrast, thinness, foldability, flexibility, and portability. Currently, most OLED panels are based on organic light-emitting diode (OLED) technology. However, OLED panels suffer from dark spot problems during display, where the OLEDs fail to emit light. A high percentage of dark spots degrades the display's overall performance. Technical issues

[0003] This application provides a photosensitive composition, a pixel definition layer, and a display panel to improve the problem of dark spots appearing when the display panel is displayed. Technical solutions

[0004] In a first aspect, embodiments of this application provide 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] Secondly, embodiments of this application also provide a display panel. The display panel includes the aforementioned pixel definition layer.

[0006] Thirdly, embodiments of this application also provide a photosensitive composition. The photosensitive composition includes a photocurable monomer, a photoinitiator, and a plurality of pigments. The plurality of pigments includes a first pigment, the first pigment having a particle size less than or equal to 90 nanometers. Beneficial effects

[0007] In some embodiments of the photosensitive composition, pixel definition layer, and display panel of this application, the first pigment can reduce the surface roughness of the pixel definition layer, improve the problem of short circuits in the light-emitting device due to the excessive surface roughness of the pixel definition layer, and thereby improve the problem of dark spots appearing in the display panel due to short circuits during display. Attached Figure Description

[0008] Figure 1 is a schematic diagram of the structure of the display panel provided in an embodiment of this application.

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

[0010] The reference numerals in the attached figures are as follows: 100, display panel; 11, substrate; 21, driving circuit layer; 31, light-emitting device layer; 310, pixel definition layer; 311, pigment; 311A, first pigment; 312, dam; 313, pixel opening; 320, anode layer; 330, cathode layer; 340, organic light-emitting layer; R, red organic light-emitting layer; G, green organic light-emitting layer; B, blue organic light-emitting layer; 41, thin film encapsulation layer; 51, color filter layer; 511, black matrix layer; 511A, light-transmitting opening; 512, first filter unit; 513, second filter unit; 514, third filter unit. Embodiments of the present invention

[0011] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0012] Please refer to Figure 1. This application embodiment 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.

[0013] The substrate 11 may include at least one of a rigid substrate and a flexible substrate. For example, the substrate 11 includes a rigid substrate such as a glass substrate.

[0014] The driving circuit layer 21 includes multiple pixel driving circuits. The pixel driving circuits include driving devices, including but not limited to thin-film transistors.

[0015] 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 disposed around the pixel opening 313. The pixel opening 313 exposes a portion of the anode. In some embodiments, a plurality of organic light-emitting layers 340 emitting multiple different colors of light may be located in a plurality of pixel openings 313, for example, a red organic light-emitting layer R, a green organic light-emitting layer G, and a blue organic light-emitting layer B may be located in a plurality of pixel openings 313. In other embodiments, an organic light-emitting layer 340 may be located within the pixel opening 313 and on the pixel dam 312 outside the pixel opening 313. For example, a white light-emitting organic light-emitting layer may be located within multiple pixel openings 313 and on the pixel dam 312 outside the pixel openings 313. A 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.

[0016] In some embodiments, the thickness of the pixel definition layer 310 is 0.5 micrometers to 3 micrometers. This ensures that the pixel dam 312 of the pixel definition layer 310 can play a role in preventing crosstalk and reduces its manufacturing difficulty.

[0017] In some embodiments, referring to FIG1, the pixel definition layer 310 includes a polymer and a plurality of pigments 311 to give the pixel definition layer 310 a specific color.

[0018] Multiple pigments 311 are dispersed in the polymer, including a first pigment 311A. The particle size of the first pigment 311A ​​is less than or equal to 90 nanometers. This improves the problem of excessively large particle size of the first pigment 311A ​​leading to a large surface roughness of the pixel definition layer 310, thereby mitigating the problem of short circuits in the light-emitting device due to the excessive surface roughness of the pixel definition layer 310, and further improving the problem of dark spots appearing in the display panel 100 during display due to short circuits.

[0019] In some embodiments, the particle size of the first pigment 311A ​​is greater than or equal to 60 nanometers to improve the problem of aggregation of the first pigment 311A ​​due to its small particle size, thereby reducing the problem of excessive surface roughness of the pixel definition layer 310 caused by the aggregation of the first pigment 311A. This improves the problem of short circuits in the light-emitting device due to excessive surface roughness of the pixel definition layer 310, and further improves the problem of dark spots appearing when the display panel 100 is displayed.

[0020] 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. Thus, controlling the particle size of the first pigment 311A ​​within a suitable range mitigates the problem that an excessively large particle size of the first pigment 311A ​​directly leads to excessive surface roughness of the pixel definition layer 310, and also mitigates the problem that an excessively small particle size of the first pigment 311A ​​causes it to easily aggregate, thereby leading to excessive surface roughness of the pixel definition layer 310.

[0021] Optionally, the particle size of the first pigment 311A ​​can be 60 nm to 75 nm, 70 nm to 85 nm, or 80 nm to 90 nm.

[0022] Understandably, the particle size of each of the multiple 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.

[0023] In some embodiments, when the particle size of the first pigment 311A ​​is less than or equal to 90 nanometers, the percentage of the first pigment 311A ​​in the plurality of pigments 311 is greater than or equal to 40%. This ensures that the percentage of the first pigment 311A ​​in the plurality of pigments 311 is relatively large, further improving the problem of short circuits in the light-emitting device due to the excessive surface roughness of the pixel definition layer 310.

[0024] It should be noted that the statistical method for the percentage of the first pigment 311A ​​among the multiple pigments 311 includes, but is not limited to: 1) selecting at least three different regions in the pixel definition layer 310, each region having the same number of pigments 311, for example, 50; 2) counting the number of the first pigment 311A ​​in each region; 3) summing the number of the first pigment 311A ​​in at least three regions, and dividing the total number of the first pigment 311A ​​by the total number of pigments 311 in the three regions to obtain the percentage of the first pigment 311A ​​among the multiple pigments 311.

[0025] In some embodiments, when the particle size of the first pigment 311A ​​is less than or equal to 90 nanometers, the percentage of the first pigment 311A ​​in the plurality of pigments 311 is greater than or equal to 50%. This further increases the percentage of the first pigment 311A ​​in the plurality of pigments 311 and reduces the percentage of pigments 311 with a size greater than 90 nanometers, further improving the problem of short circuits in the light-emitting device due to excessive surface roughness of the pixel definition layer 310.

[0026] Optionally, when the particle size of the first pigment 311A ​​is less than or equal to 90 nanometers, the percentage of the first pigment 311A ​​in the plurality of pigments 311 is greater than or equal to 55%, or the percentage of the first pigment 311A ​​in the plurality of pigments 311 is greater than or equal to 60%, or the percentage of the first pigment 311A ​​in the plurality of pigments 311 is greater than or equal to 65%, or the percentage of the first pigment 311A ​​in the plurality of pigments 311 is greater than or equal to 70%.

[0027] In some embodiments, the 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.

[0028] 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, by controlling the first pigment 311A ​​with a suitable particle size to have a large percentage, the surface roughness of the pixel definition layer 310 is reduced.

[0029] Optionally, 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 60%, 65%, 70% or 75%.

[0030] In some embodiments, the peaks of the number particle size distribution of the plurality of pigments 311 correspond to particle sizes of 60 nanometers to 90 nanometers. Thus, the proportion of pigments with particle sizes of 60 nanometers to 90 nanometers is larger, reducing the surface roughness of the pixel definition layer 310.

[0031] Optionally, the peaks of the number particle size distribution of the multiple pigments 311 correspond to particle sizes of 65 nm to 88 nm or 75 nm to 85 nm.

[0032] In some embodiments, the plurality of pigments 311 further includes a second pigment (not shown in the figure), the particle size of which is larger than that of the first pigment 311A. The particle size of the second pigment is greater than 90 nanometers. The percentage of the second pigment in the plurality of pigments 311 is less than or equal to 5%. Thus, reducing the percentage of the second pigment reduces the risk that the larger particle size of the second pigment will cause a larger surface roughness of the pixel definition layer 310.

[0033] In some embodiments, among the plurality of pigments 311, the proportion of pigments 311 with a particle size of less than 60 nanometers is less than the proportion of the first pigment 311A ​​with a particle size of 60 nanometers to 90 nanometers. In this way, the proportion of the first pigment 311A ​​with a particle size of 60 nanometers to 90 nanometers is ensured to be larger, thereby reducing the surface roughness of the pixel definition layer 310.

[0034] In some embodiments, among the plurality of pigments 311, the percentage of the number of the second pigment is less than the percentage of the number of pigments 311 with a particle size of less than 60 nanometers. Reducing the percentage of the number of the second pigment reduces the risk that the larger particle size of the second pigment will cause greater surface roughness of the pixel definition layer 310.

[0035] In some embodiments, the proportion of pigments 311 with a particle size of less than 60 nanometers may be less than or equal to 10%. This reduces the risk of aggregation of pigments 311 with a particle size of less than 60 nanometers, improves the dispersion uniformity of pigments 311 in the polymer, improves the uniformity of light reflectivity at different locations of the pixel definition layer 310, and reduces the surface roughness of the pixel definition layer 310.

[0036] Optionally, among the multiple pigments 311, the proportion of pigments 311 with a particle size of less than 60 nanometers can be less than or equal to 8%, 5%, or 3%.

[0037] In some embodiments, the pixel definition layer 310 with a thickness of 1 micrometer has a visible light density of less than or equal to 1.2. This mitigates the problem of excessively high pigment 311 mass percentage in the pixel definition layer 310 leading to high roughness, and further mitigates the problem of high roughness resulting in a high proportion of dark spots.

[0038] It should be noted that optical density (OD) is a measure used to describe a material's ability to absorb light. It represents the degree to which light is absorbed as it passes through a material and is commonly used in optics and spectroscopy. Optical density is defined in relation to transmittance (T), which is the ratio of the intensity of light transmitted through a material to the intensity of incident light. For pixel definition layer 310, a higher optical density indicates a higher mass percentage of pigment 311 in pixel definition layer 310.

[0039] In some embodiments, the pixel definition layer 310, with a thickness of 1 micrometer, has a visible light density greater than or equal to 0.4. This improves the problem of low light reflectivity caused by an excessively low mass percentage of pigment 311 in the pixel definition layer 310, thereby enhancing the display contrast of the display panel.

[0040] Optionally, the pixel definition layer 310 with a thickness of 1 micrometer has a visible light density of 0.5–1.15, 0.6–1.1, 0.7–1, 0.8–1.2, or 0.4–1.

[0041] 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. This lower surface roughness reduces the risk that a thinner light-emitting layer or similar material may not be able to cover the surface of the pixel definition layer 310, thereby mitigating the problem of dark spots forming in pixels due to localized short circuits in the light-emitting device.

[0042] 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.

[0043] It should be noted that the instruments for measuring the root mean square roughness of the surface of the pixel definition layer 310 include, but are not limited to, atomic force microscopes.

[0044] In some embodiments, the plurality of pigments 311 include a plurality of black pigments, so that the pixel definition layer 310 is black, thereby reducing the reflectivity of the pixel definition layer 310 to light and improving the display contrast of the display panel 100.

[0045] In some embodiments, where the plurality of pigments 311 include a plurality of black pigments, the plurality of pigments 311 may include organic black pigments. Organic black pigments include 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 dinaphthalene black. Azo black includes, but is not limited to, aniline black.

[0046] In other embodiments, where the plurality of pigments 311 include a plurality of black pigments, the plurality of pigments 311 may include an inorganic black pigment.

[0047] In other embodiments, the plurality of pigments 311 may also include pigments other than black pigments, such as one or more of red pigments, green pigments, blue pigments, and yellow pigments.

[0048] In some embodiments, the mass ratio of the plurality of pigments 311 to the polymer is (1-5):(6-13). This ensures a suitable mass ratio between the pigments 311 and the polymer, reducing the surface roughness of the pixel definition layer 310 while maintaining low light reflectivity. Furthermore, it ensures that the polymer provides sufficient heat resistance, improving its stability during high-temperature processes.

[0049] Optionally, the mass ratio of the plurality of pigments 311 to the mass of the polymer is (2-4):(6-13).

[0050] In some embodiments, the polymer is obtained by photocuring monomers through the initiation of a photoinitiator. Before the photocuring monomers are cured, the initial pixel definition layer can be patterned using a developer to achieve patterning of the initial pixel definition layer 310. After patterning, the photocuring monomers are cured to improve the mechanical properties and high-temperature resistance of the pixel definition layer 310.

[0051] In some embodiments, the photocurable monomer includes a polymeric monomer, which may include a resin having alkali-soluble groups. The alkali-soluble groups include carboxyl and / or hydroxyl groups. Resins having alkali-soluble groups include at least one of alkaline calomel resin, alkali-soluble acrylic resin, and alkali-soluble polybenzoxazole resin. Thus, patterning of an initial pixel definition layer including a resin having alkali-soluble groups can be achieved using an alkaline developer.

[0052] In some embodiments, the photocurable monomer further includes a multifunctional monomer. The multifunctional monomer plays a role in crosslinking the polymeric monomers during the photocuring process, thereby improving the polymer's high-temperature resistance.

[0053] In some embodiments, the multifunctional monomer comprises two or more vinyl unsaturated double bonds. In some embodiments, the multifunctional monomer comprises one or more of the following: 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.

[0054] In some embodiments, the mass ratio between the polymeric monomer and the multifunctional monomer is (5-10):(1-3). This ensures that the pixel definition layer 310 has suitable mechanical properties and high-temperature resistance.

[0055] Optionally, the mass ratio between the polymeric monomer and the multifunctional monomer is (6-8):(1-3).

[0056] 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 acts as a barrier against water vapor and oxygen, reducing the risk of water vapor and oxygen penetrating into the light-emitting device layer 31 and causing it to fail.

[0057] In some embodiments, the thin-film encapsulation layer comprises 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 comprises at least one of silicon oxide, silicon nitride, and silicon oxynitride. The organic thin-film encapsulation layer comprises at least one of polyacrylate and epoxy resin.

[0058] 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 facing 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 first filter unit, the second filter unit, and the third filter unit are different colors from each other. The black matrix layer includes a plurality of light-transmitting openings. The first to third filter units are all located in the plurality of light-transmitting openings. The plurality of light-transmitting openings overlap with a plurality of pixel openings 313, ensuring 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, improving the display effect of the display panel 100, but also reduces the reflectivity of light incident on the display panel 100 from the outside, reduces the interference of ambient light on the display panel 100, and improves the display contrast. In addition, the color filter layer is thinner than a polarizer, which can reduce the overall thickness of the display device.

[0059] 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 facing away from the substrate 11. In this way, the reflectivity of light incident on the display panel 100 from the outside is reduced by using a circular polarizer, thereby reducing the interference of ambient light on the display panel 100 and improving the display contrast.

[0060] In some embodiments, the opening area of ​​the light-transmitting opening is larger than the opening area of ​​the pixel opening 313, ensuring that the light emitted by the organic light-emitting layer 340 is emitted from the multiple light-transmitting openings. Furthermore, since the first pixel definition layer 310 is colored black by black pigment, it has low reflectivity, resulting in less reflection of light incident from the outside onto the pixel definition layer 310, thus improving display contrast.

[0061] 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, which may be self-capacitive touch electrodes or mutual-capacitive touch electrodes.

[0062] Furthermore, this application embodiment also provides a photosensitive composition, wherein the pixel defining layer 310 is prepared from the photosensitive composition. The photosensitive composition includes a photocurable monomer, a photoinitiator, and a plurality of pigments 311, wherein the plurality of pigments 311 includes a first pigment 311A. The particle size of the first pigment 311A ​​is less than or equal to 90 nanometers. Thus, the pixel defining layer 310 prepared from the photosensitive composition includes the first pigment 311A, reducing the surface roughness of the pixel defining layer 310, improving the problem of short circuits in the light-emitting device due to the excessive surface roughness of the pixel defining layer 310, and further improving the problem of dark spots appearing due to short circuits when the display panel 100 is displayed.

[0063] It should be noted that the design of multiple pigments 311 can be the same as the design of multiple pigments 311 in the pixel definition layer 310 mentioned above, and will not be repeated here.

[0064] In some embodiments, the plurality of pigments 311 include a plurality of black pigments, such that the organic polymer layer prepared from the photosensitive composition has low reflectivity to visible light.

[0065] In some embodiments, the photosensitive composition comprises, by weight percentage: 1%–5% pigment 311; 5%–10% polymeric monomer; 1%–3% multifunctional monomer; 1%–3% photoinitiator; and the balance being solvent. This not only improves the yield of the initial pixel definition layer 310 during the development process but also ensures the high-temperature resistance of the patterned initial pixel definition layer after curing.

[0066] In some embodiments, the photosensitive composition comprises, by weight percentage: 2%–4% pigment 311; 6%–8% polymeric monomer; 1%–3% multifunctional monomer; 1%–3% photoinitiator; and the balance being solvent. This not only improves the yield of the initial pixel definition layer during the development process but also ensures the high-temperature resistance and low light reflectivity of the patterned initial pixel definition layer after curing.

[0067] In some embodiments, the polymeric monomer may include a resin having alkali-soluble groups. Alkali-soluble groups include carboxyl and / or hydroxyl groups. Resins having alkali-soluble groups include at least one of alkaline calomel resin, alkali-soluble acrylic resin, and alkali-soluble polybenzoxazole resin. Thus, patterning of the initial pixel definition layer 310, including the resin having alkali-soluble groups, can be achieved using an alkaline developer.

[0068] 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 the following: 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.

[0069] In some embodiments, the photoinitiator may include, but is not limited to, oxime ester-based photopolymerization initiators.

[0070] In some embodiments, the solvent may include at least one of ether solvents and ester solvents. Ester solvents include at least one of 3-methoxy-3-methyl acetate, propylene glycol methyl ether acetate, and oxybutyl acetate. Ether solvents include, but are not limited to, propylene glycol methyl ether.

[0071] In some embodiments, the photosensitive composition further includes additives such as dispersants. The dispersant comprises 0.01% to 1% by mass in the photosensitive composition. This improves the uniformity of pigment 311 dispersion in the polymer, not only mitigating the problem of high roughness in the pixel definition layer 310 caused by pigment 311 aggregation, but also enhancing the uniformity of light reflectance in different regions of the pixel definition layer 310.

[0072] In some embodiments, the dispersant may include at least one of nonionic dispersants, anionic dispersants, and cationic dispersants. Nonionic dispersants may include, but are not limited to, at least one of polydiols and their esters, carboxylic acid esters, and polyoxyethylene. Anionic dispersants may include at least one of sulfonates, sulfonates, and carboxylates.

[0073] In summary, in some embodiments of the photosensitive composition, pixel definition layer, and display panel of this 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. Thus, the first pigment 311A ​​can reduce the surface roughness of the pixel definition layer, improving the problem of short circuits in the light-emitting device due to excessive surface roughness of the pixel definition layer, thereby improving the problem of dark spots appearing in the display panel due to short circuits.

[0074] The performance of the photosensitive composition and pixel definition layer of the present application embodiments is verified below with reference to specific examples and comparative examples.

[0075] The black pigment in Comparative Example 1 was a raw black pigment (particle size greater than or equal to 120 nm), purchased from BASF's Irgaphor Black S0100 CF. The black pigments in Examples 1 to 5 were obtained by ball milling the raw black pigment. The polymer monomers in Examples 1 to 5 and Comparative Example 1 were alkali-soluble Cardo resins (amine value 0 (mg KOH / g), resin acid value 90 (mg KOH / g)), purchased from ADEKA ARKLS WR-301. The polyfunctional monomer was tetraethylene glycol diacrylate, purchased from Dong-A Synthetic Chemical Industry Co., Ltd.'s Aronix M-240. The photocuring agent was 1-(O-acetyl oxime), purchased from BASF's OXE02. The dispersant was BYK's DISPERBYK-101. The solvent was 3-methoxy-3-methyl acetate butyl ester, which was commercially available.

[0076] Table 1. Photosensitive compositions of Examples 1 to 5 and Comparative Example 1

[0077] The peak in the number particle size distribution corresponds to a particle size of 60 nm, meaning that among multiple black pigments, those with a particle size of 60 nm constitute the largest proportion. The peaks in the number particle size distribution corresponding to particle sizes of 80 nm, 90 nm, and 140 nm can be deduced similarly, and will not be elaborated upon here.

[0078] Examples 6 to 10 and Comparative Example 2

[0079] 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 micrometer, and the pixel definition layers were tested as follows.

[0080] 1) Root mean square roughness test

[0081] The root mean square roughness of the surface of the pixel definition layer was observed using an atomic force microscope.

[0082] 2) Optical density test

[0083] The optical density of the pixel definition layer was tested using a D65 light source. Optical density = (lg(1 / Tr)) / Thk, where Tr is the light transmittance of the pixel definition layer and Thk is the thickness of the pixel definition layer.

[0084] 3) SEM test 1

[0085] The number of black pigments with a surface particle size greater than 200 nanometers in the pixel definition layer was observed using scanning electron microscopy.

[0086] Table 2 Examples 6 to 10 and Comparative Example 2

[0087] As can be seen from Table 2 and Figures 2 to 5, the roughness of the pixel definition layer in Examples 6 to 10 is less than that in Comparative Example 2. Therefore, compared to the particle size of the black pigment in Comparative Example 1, the peak of the number particle size distribution of the black pigment in the photosensitive compositions of Examples 1 to 5 corresponds to a particle size of 60 nm to 90 nm, which can reduce the number of black pigments with a surface particle size greater than 200 nm in the pixel definition layer, thereby reducing the roughness of the pixel definition layer and also reducing the optical density of the pixel definition layer.

[0088] As can be seen from Examples 7 and 9, the higher the mass percentage of black pigment in the photosensitive composition, the greater the optical density of the pixel definition layer.

[0089] Examples 11 to 13 and Comparative Example 3

[0090] Examples 11 to 13 and Comparative Example 3 all provide display panel motherboards. Each display panel motherboard includes multiple display panels, and the structure of each display panel is shown in Figure 1. The pixel definition layer of the display panel motherboards in Examples 11 to 13 and Comparative Example 3 was prepared using the formulations of Examples 1 to 2, Example 5, and Comparative Example 1. The display panel motherboards were tested as follows.

[0091] 4) Dark spot test:

[0092] For each of Examples 11 to 13 and Comparative Example 3, 2000 display panels on a single display panel motherboard were used as a group of test samples. Each display panel was lit up, and an automatic optical inspection device was used to inspect a certain area of ​​the image on each display panel (for example, this certain area includes 10,000 pixels). When the number of unlit pixels exceeded one, the image of that display panel was 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.

[0093] 5) SEM Test 2

[0094] The cathode layer in the display panel was observed using a scanning electron microscope.

[0095] 6) TEM test

[0096] The black pigment in the pixel definition layer of the display panel was observed using a transmission electron microscope.

[0097] Table 3 shows the test results of the display panels of Examples 11 to 13 and Comparative Example 3.

[0098] As shown in Table 3, the dark spot ratio of the display panels in Examples 11 to 13 is significantly lower than that in Comparative Example 3. Furthermore, the particle size of the black pigment on the surface of the pixel definition layer in Examples 12 and 13 is smaller than that of the black pigment on the surface of the pixel definition layer in Comparative Example 3. Therefore, compared to 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 compositions in Examples 1 to 2 and 5 can reduce the roughness of the pixel definition layer, improve the wrinkling problem of the cathode layer on the pixel definition layer, and thus significantly reduce the dark spot ratio of the display panel.

[0099] The above description of the embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application; those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A pixel definition layer, wherein, include: polymer; Multiple pigments are dispersed in the polymer, including a first pigment having a particle size of less than or equal to 90 nanometers.

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

3. The pixel definition layer according to claim 1, wherein, 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, wherein, Of the plurality of pigments, the percentage of the first pigment is greater than or equal to 50%.

5. The pixel definition layer according to claim 1, wherein, The plurality of pigments further includes a second pigment having a particle size 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, wherein, The pixel definition layer, with a thickness of 1 micrometer, has a visible light density of less than or equal to 1.

2.

7. The pixel definition layer according to claim 6, wherein, The pixel definition layer, with a thickness of 1 micrometer, has a visible light density greater than or equal to 0.

4.

8. The pixel definition layer according to claim 1, wherein, 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, wherein, The plurality of pigments include a plurality of black pigments, and the mass ratio 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, wherein, The polymer is obtained by photocuring monomers through the initiation of a photoinitiator, wherein the photocuring monomers include resins having alkali-soluble groups.

11. A display panel, wherein, Includes a pixel definition layer, the pixel definition layer including: polymer; Multiple pigments are dispersed in the polymer, including a first pigment having a particle size of less than or equal to 90 nanometers.

12. The display panel according to claim 11, wherein, The particle size of the first pigment is greater than or equal to 60 nanometers.

13. The display panel according to claim 11, wherein, The particle size of the first pigment is greater than or equal to 65 nanometers and less than or equal to 85 nanometers.

14. The display panel according to claim 11, wherein, Of the plurality of pigments, the percentage of the first pigment is greater than or equal to 50%.

15. The display panel according to claim 11, wherein, The plurality of pigments further includes a second pigment having a particle size greater than 90 nanometers; and the number percentage of the second pigment in the plurality of pigments is less than or equal to 5%.

16. The display panel according to claim 11, wherein, The pixel definition layer, with a thickness of 1 micrometer, has a visible light density of less than or equal to 1.

2.

17. A photosensitizing composition, wherein, include: Photocurable monomers; Photoinitiator; as well as Multiple pigments, including a first pigment, wherein the particle size of the first pigment is less than or equal to 90 nanometers.

18. The photosensitizing composition according to claim 17, wherein, The particle size of the first pigment is greater than or equal to 60 nanometers.

19. The photosensitizing composition according to claim 17, wherein, The photosensitizing composition comprises, by weight percentage: 1%–5% pigment; 5%–10% monomer; 1%–3% multifunctional monomers; 1%–3% photoinitiator; and The remainder is solvent.

20. The photosensitizing composition according to claim 17, wherein, The multiple pigments include multiple black pigments, and / or the photosensitive composition also includes a dispersant.

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