WO2022152062A1 - 显示面板 - Google Patents

显示面板 Download PDF

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Publication number
WO2022152062A1
WO2022152062A1 PCT/CN2022/070887 CN2022070887W WO2022152062A1 WO 2022152062 A1 WO2022152062 A1 WO 2022152062A1 CN 2022070887 W CN2022070887 W CN 2022070887W WO 2022152062 A1 WO2022152062 A1 WO 2022152062A1
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Prior art keywords
light
display panel
sub
light extraction
layer
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PCT/CN2022/070887
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English (en)
French (fr)
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顾辛艳
艾文玲
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纳晶科技股份有限公司
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Publication of WO2022152062A1 publication Critical patent/WO2022152062A1/zh

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/80—Constructional details
    • H10K50/85—Arrangements for extracting light from the devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/80—Constructional details
    • H10K50/85—Arrangements for extracting light from the devices
    • H10K50/858—Arrangements for extracting light from the devices comprising refractive means, e.g. lenses
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/30—Devices specially adapted for multicolour light emission
    • H10K59/35—Devices specially adapted for multicolour light emission comprising red-green-blue [RGB] subpixels

Definitions

  • the present disclosure relates to the field of optoelectronic technology, and in particular, to a display panel.
  • OLED Organic Light Emitting Diode
  • OLED Organic Light Emitting Diode
  • the electrodes of this type of electroluminescent device generally, the electrode on one side is metal
  • the circular polarizer has become an indispensable component of the display panel, but its introduction will cause about half of the light output loss.
  • the top emission panel with high aperture ratio has become the focus of research in this field.
  • Setting a capping layer on top of a top-emission display panel has become a conventional method to improve its external quantum efficiency, but the improvement ratio is still very limited.
  • the lens-type and scattering-type light extraction structures can significantly improve the light extraction efficiency of the display panel, but when they are used in combination with the circular polarizer, the effect of the circular polarizer on the reflection of ambient light will be destroyed, that is, When the display panel is not lit, the circular polarizer is used to observe the display panel, and the "dark field" effect of all-in-one black can no longer be seen (the effect of all-in-one black refers to ambient light entering but not exiting), Instead, it presents a certain gray, and the destruction of the "dark field” effect will have a great impact on the contrast ratio of the display panel.
  • the purpose of the present disclosure is to provide a display panel, including an anti-reflection film and a light-emitting element, the light-emitting element includes a substrate and a plurality of mutually isolated sub-pixels disposed on one side surface of the substrate, each of the sub-pixels including sequentially stacked sub-pixels
  • the bottom electrode, the functional layer and the top electrode, at least some of the sub-pixels also include a light extraction layer, the light extraction layer is arranged on the side surface of the top electrode away from the functional layer, and nanoparticles are provided in the light extraction layer. , the particle size of the above-mentioned nanoparticles does not exceed 40nm.
  • the mass fraction of the nanoparticles contained in the light extraction layer is ⁇ 70 wt %.
  • the mass fraction of the nanoparticles contained in the light extraction layer is greater than or equal to 50 wt %, and the light extraction layer includes a polymer matrix, and the refractive index of the polymer matrix is greater than 1.65.
  • the particle size of the above-mentioned nanoparticles is 5-30 nm.
  • the refractive index of the above-mentioned nanoparticles is greater than or equal to 1.8.
  • the surfaces of the above-mentioned nanoparticles are curved surfaces.
  • the above-mentioned nanoparticles are selected from any one or more of zinc oxide, titanium oxide, tantalum pentoxide, yttrium oxide, zirconium oxide, aluminum oxide, niobium oxide, tungsten oxide, antimony oxide, vanadium oxide, and molybdenum oxide. combination of species.
  • the thickness of the above-mentioned light extraction layer is 0.5-10 ⁇ m.
  • the flatness Ra of the above-mentioned light extraction layer is less than or equal to 20 nm.
  • the transmittance of the above-mentioned light extraction layer does not exceed 80%.
  • the above-mentioned light extraction layer includes at least one auxiliary material, and under the irradiation of visible light, the light transmittance of the above-mentioned auxiliary material is not less than 80%.
  • the total mass fraction of the above-mentioned auxiliary materials in the above-mentioned light extraction layer is not more than 30 wt %, and the refractive index of each of the above-mentioned auxiliary materials is not less than 1.4.
  • the above-mentioned auxiliary material includes an interface modifier, and the above-mentioned interface modifier is coordinated on the surface of the above-mentioned nanoparticles.
  • the light-emitting element further includes an interface layer, the interface layer is disposed on the surface of the light extraction layer on the side away from the substrate, and the transmittance of the interface layer is not lower than the light with a wavelength of 550 nm. 80%, the refractive index of the interface layer is less than or equal to 1.8.
  • the thickness of the above-mentioned interface layer is 0.1-5 ⁇ m.
  • the sub-pixel with the highest original external quantum efficiency is defined as the first sub-pixel, the sub-pixel with the lowest original external quantum efficiency is the third sub-pixel, and the original external quantum efficiency is between the first sub-pixel and the third sub-pixel.
  • the sub-pixel between the sub-pixels is the second sub-pixel; the external quantum efficiency improvement ratio of the light extraction layer to the first sub-pixel is X 1 , and the external quantum efficiency improvement ratio of the light extraction layer to the second sub-pixel is X 1 .
  • X 2 is X 2
  • the external quantum efficiency improvement ratio of the light extraction layer to the third sub-pixel is X 3
  • the X 1 , the X 2 and the X 3 are not equal
  • X n (Q 2 -Q 1 )/ Q 1 , where n is selected from any natural number from 1 to 3
  • Q 1 is the original external quantum efficiency corresponding to the sub-pixel
  • Q 2 is the actual external quantum efficiency corresponding to the sub-pixel; the above X n ⁇ 0.5.
  • the display panel when the display panel is not lit, the display panel presents the effect of being all black.
  • the external quantum efficiency of the display panel is greatly improved, and the dark field of the anti-reflection film is not affected at the same time. Therefore, the effect of improving the service life of the display panel is achieved under the condition of ensuring that the display panel has a high contrast ratio.
  • FIG. 1 shows a schematic cross-sectional structure diagram of a display panel according to an embodiment of the present disclosure
  • FIG. 2 shows a schematic cross-sectional structure diagram of a display panel according to an embodiment of the present disclosure
  • FIG. 3 shows a schematic cross-sectional structure diagram of a display panel according to an embodiment of the present disclosure
  • FIG. 4 shows a schematic cross-sectional structure diagram of a display panel according to an embodiment of the present disclosure
  • FIG. 5 is a photograph of the light-emitting element with circular polarizer of Comparative Example 2 and Examples 1, 2, 6, 7, and 8 of the present disclosure in an unlit state, and the first row corresponds to Comparative Example 2 from left to right. , Example 1, Example 2, the second row corresponds to Example 6, Example 7, and Example 8 in order from left to right (the circle in the photo is the bubble caused by the film sticking).
  • Substrate 1. Substrate; 2. Pixel isolation structure; 3. Bottom electrode; 4. Functional layer; 5. Top electrode; 6. Light extraction layer; 7. Anti-reflection film; 8. Encapsulation layer; 9. Interface layer.
  • the lens-type and scattering-type light extraction structures in the prior art can significantly improve the light extraction efficiency of the display panel, but when they are used in combination with a circular polarizer, the effect of the circular polarizer on the reflection of ambient light will be destroyed.
  • the inventor's research found that the main reason for the above problem is that the combination of the circular polarizer and the specular reflection can achieve an integrated black effect, and the above-mentioned light extraction structure or other film layers and components located on the side of the circular polarizer near the substrate will cause the problem. Destruction of specular reflection results in part of the light that cannot be absorbed by the circular polarizer, so that part of the light will be reflected and enter the human eye.
  • the present disclosure provides a display panel, including an anti-reflection film 7 and a light-emitting element, the light-emitting element includes a substrate 1 and a plurality of mutually isolated sub-pixels disposed on a surface of one side of the substrate 1 , each sub-pixel includes a bottom electrode stacked in sequence 3.
  • the functional layer 4, the top electrode 5, and at least some of the sub-pixels also include a light extraction layer 6.
  • the light extraction layer 6 is arranged on the surface of the top electrode 5 away from the functional layer 4, and the light extraction layer 6 is provided with nanoparticles. , the particle size of nanoparticles does not exceed 40nm.
  • the technical solution of the present disclosure adopts nano-scale small particle size particles as light-extracting particles, and arranges a light-extracting layer above the top electrode.
  • an anti-reflection film such as circularly polarized light.
  • the remaining half of the light exits the anti-reflection film and reaches the interface of the light extraction layer, most of the light is reflected by the reflective interface and then re-emitted to the anti-reflection film, and the phase of the reflected light is just in line with the anti-reflection film. In this way, almost all ambient light is absorbed by the anti-reflection film, thereby reducing the adverse effect of ambient light on the contrast ratio of the display panel.
  • the external quantum efficiency of the display panel is greatly improved, and at the same time, the dark field effect of the anti-reflection film is not affected. Under the condition of ensuring that the display panel has a high contrast ratio, the effect of improving the service life of the display panel is achieved.
  • the above-mentioned nanoparticles function as light-extracting particles in the light-extracting layer, and the nanoparticles have no light-conversion function, and the light-extracting layer does not include micron-scale light-extracting particles.
  • the particle diameter of the above-mentioned nanoparticles refers to the average particle diameter of the nanoparticles.
  • the particle size of the nanoparticles in the light extraction layer deviates within plus or minus 25%, preferably within plus or minus 10%. On the premise that the particle size does not exceed 40 nm, the nanoparticles with good particle size uniformity are beneficial to obtain a light extraction layer with good flatness.
  • At least part of the sub-pixels further include the light extraction layer 6 ” means that at least part of the top electrode 5 is covered by the light extraction layer 6 .
  • the light extraction layer 6 is a continuous layer, in other embodiments, the light extraction layer 6 comprises a plurality of spaced layers arranged in an array.
  • the above-mentioned light-emitting element further includes a plurality of pixel isolation structures 2 (also referred to as banks) disposed on the substrate 1, and a plurality of mutually isolated light-emitting regions defined and formed by the pixel isolation structures 2, and the above-mentioned plurality of sub-pixels They are arranged in a plurality of light-emitting regions in a one-to-one correspondence.
  • pixel isolation structures 2 also referred to as banks
  • the functional layer 4 of each sub-pixel may include an electron injection layer, an electron transport layer, a light emitting layer, a hole transport layer and a hole injection layer stacked in sequence.
  • the light-emitting element and the anti-reflection film 7 are arranged in parallel, and other layers (eg, an encapsulation layer 8 ) may be arranged between the light-emitting element and the anti-reflection film 7 .
  • other structures are also arranged on the outside of the anti-reflection film 7 to form a complete display panel.
  • the display panel includes an encapsulation layer 8 located on a side of the light extraction layer 6 away from the substrate 1 .
  • the encapsulation layer can improve the water and oxygen barrier properties of the display panel.
  • the stacked layers of the thin-film encapsulation can be arranged on the surface of the light-extraction layer to flatten the light-extraction layer. effect.
  • the display panel further includes a layer between the encapsulation layer 8 and the anti-reflection film 7 .
  • the light extraction layer 6 may be disposed on the entire surface of the top electrode 5 , as shown in FIG. 3 . In this way, the light-emitting device can be prepared by a coating process, and the preparation method is simple.
  • the anti-reflection film 7 in the display panel is a circular polarizer.
  • the anti-reflection film can also be selected from other substitutes in the technical field that have the same or similar effect as the circular polarizer.
  • the anti-reflection film plays the role of preventing ambient light from being reflected by the panel to be emitted, and mixing with the self-luminous light of the panel to reduce the contrast ratio of the display panel.
  • the nanoparticles have a particle size greater than 1 nm but not greater than 3 nm, or not greater than 5 nm, or not greater than 7 nm, or not greater than 9 nm, or not greater than 13 nm, or not greater than 16 nm, or not greater than 19 nm, or not greater than More than 21nm, or not more than 24nm, or not more than 27nm, or not more than 29nm, or not more than 33nm, or not more than 36nm, or not more than 39nm.
  • the nanoparticles have a particle size of 5-30 nm.
  • the nanoparticles have a particle size of 10-25 nm. The above particle size can ensure that the nanoparticles have high refractive index and light extraction effect.
  • the mass fraction of nanoparticles contained in the light extraction layer 6 is ⁇ 70 wt %, or ⁇ 75 wt %, or ⁇ 80 wt %, or ⁇ 85 wt %, or ⁇ 90 wt %, or ⁇ 95 wt %.
  • the above-mentioned mass fraction of nanoparticles can ensure that the comprehensive refractive index of the light extraction layer is relatively high.
  • Comprehensive refractive index ⁇ (volume ratio of a single component)*(refractive index value of a single component).
  • the mass fraction of nanoparticles contained in the light extraction layer 6 is ⁇ 50 wt %, or ⁇ 55 wt %, or ⁇ 60 wt %, or ⁇ 65 wt %, and the light extraction layer includes a polymer matrix, and the above-mentioned polymer matrix The refractive index is greater than 1.65.
  • the nanoparticle has a refractive index > 1.8, or > 2.
  • the surface of the nanoparticle is a curved surface, preferably the shape of the nanoparticle is spherical, spheroid-like, ellipsoid or ellipsoid-like.
  • the packing flatness of such nanoparticles will be better.
  • the nanoparticles may be selected from any of zinc oxide, titanium oxide, tantalum pentoxide, yttrium oxide, zirconium oxide, aluminum oxide, niobium oxide, tungsten oxide, antimony oxide, vanadium oxide, molybdenum oxide or a combination of more than one, but not limited to this.
  • the thickness of the light extraction layer 6 is 0.5-10 ⁇ m, or 0.8-3 ⁇ m.
  • the flatness Ra of the light extraction layer 6 is less than or equal to 20 nm, or less than or equal to 10 nm, or less than or equal to 5 nm.
  • the above-mentioned flatness can ensure that the light extraction layer has a good reflection interface, thereby further reducing the adverse effect of ambient light on the contrast ratio of the display panel.
  • the transmittance of the light extraction layer 6 is not more than 80%, or not more than 75%, or not more than 70%, or not more than 65%, or not more than 65% under the irradiation of light with a wavelength of 550 nm 60%, or no more than 55%, or no more than 50%, or no more than 45%, or no more than 40%, or no more than 35%, or no more than 30%. It can be observed that the appearance of the light extraction layer in the above embodiments exhibits a certain degree of whiteness.
  • the light extraction layer 6 may not include a polymer matrix.
  • the nanoparticles and the solvent are mixed and then added to the sub-pixel area, and after the solvent is volatilized, the light extraction layer can be formed.
  • some small-molecule interface modifiers are pre-modified on the surface of the nanoparticles to increase the dispersibility of the nanoparticles in the solvent.
  • the nanoparticles and the solvent are mixed, the nanoparticles can be prevented from agglomerating with each other, so as to be applied to the sub-pixel area After that, the light extraction layer will be relatively uniform due to particle dispersion.
  • the light extraction layer 6 may comprise a polymer matrix.
  • the polymer matrix mainly plays the following roles: one is to disperse the nanoparticles, and the nanoparticles are separated by the polymer matrix to play a stabilizing role; the other is to fix the nanoparticles to make them a whole; It can play the role of filling the gaps caused by the accumulation of nanoparticles.
  • the component content of the polymer matrix is further increased, the light extraction layer can be flattened, that is, the gaps are filled, and there is even a margin to cover All nanoparticles.
  • the light extraction layer 6 includes at least one auxiliary material, and under visible light irradiation, the light transmittance of the auxiliary material is not less than 80%, preferably, the light transmittance is not less than 90%.
  • the above-mentioned light transmittance refers to the transmittance of the film obtained when the auxiliary materials in the actual light extraction ink formulation are used alone for film formation.
  • the solid content of the light extraction ink is 30wt%
  • the auxiliary material accounts for 3wt%
  • the nanometer The particles account for 27 wt%
  • the transmittance of the auxiliary material is approximately that of forming a film of the 3% auxiliary material alone, and then testing the transmittance of the film under visible light (400-700 nm).
  • the total mass fraction of auxiliary materials in the light extraction layer 6 is not more than 30 wt %, and the refractive index of each auxiliary material is not less than 1.4.
  • the auxiliary material can ensure that the comprehensive refractive index of the entire light extraction layer will not be low. On the premise of ensuring that the overall comprehensive refractive index of the light extraction layer meets the requirements, the greater the difference between the refractive index of the auxiliary material and that of the nanoparticles, the better.
  • the auxiliary material in the light extraction layer may be at least one of a binder, a viscosity modifier, an interface modifier, a rheology aid, and the like.
  • the binder can be selected from various curable resins;
  • the viscosity modifier can be selected from various polymers, such as PVK (poly(N-vinylcarbazole)), etc.;
  • the interface modifier can be a silane coupling agent or a surface active agent
  • the rheology aid can be a leveling agent, a defoaming agent, etc. Any kind of auxiliary material needs to meet the requirements of as little light absorption as possible, high transmittance, colorless and transparent.
  • the auxiliary material includes an interface modifier that is coordinated to the surface of the nanoparticle.
  • the interface modifier can increase the dispersibility of the nanoparticles in the solvent. When the nanoparticles and the solvent are mixed, the agglomeration of the nanoparticles can be avoided, so that the light extraction layer will be relatively uniform after being applied to the sub-pixel area.
  • the light-emitting element further includes an interface layer 9 (such as a first interface layer), and the interface layer 9 is disposed on the surface of the light extraction layer 6 on the side away from the substrate 1, and under the irradiation of light with a wavelength of 550 nm,
  • the transmittance of the interface layer is not less than 80%, the refractive index of the interface layer 9 is less than or equal to 1.8, preferably the refractive index of the interface layer 9 is not more than 1.5 and not less than 1.
  • the material of the interface layer 9 can be selected from inorganic materials, produced by physical vapor deposition (sputtering, evaporation) or chemical vapor deposition (CVD) process; can also be selected from organic materials, such as various resins; can also be selected from organic inorganic
  • the composite material such as a stacked structure of a layer of inorganic material combined with a layer of organic material, can also be a thin film package, which can block water and oxygen for the entire light-emitting element.
  • the thickness of the interface layer 9 is 0.1-5 ⁇ m. The above interface layer can improve the flatness of the light extraction layer.
  • the anti-reflection film such as circular polarizer
  • the remaining half of the light is emitted after the anti-reflection film.
  • the film reaches the interface on the side of the interface layer far from the light extraction layer, most of the light is reflected by the interface and re-emitted to the anti-reflection film, and the phase of the reflected light is just in line with the absorption direction of the anti-reflection film. In this way, all ambient light is absorbed by the anti-reflection film, thereby further reducing the adverse effect of ambient light on the contrast ratio of the display panel; on the other hand, the interface layer can protect the light extraction layer.
  • the interface layer 9 is provided only on the surface of the light extraction layer 6 in the light emitting region, as shown in FIG. 4 .
  • the interface layer 9 is disposed on the surface of the light extraction layer 6 and the exposed surface of the top electrode 5 , as shown in FIG. 2 .
  • the light emitting element further includes a second interface layer disposed between the top electrode and the light extraction layer.
  • the second interfacial layer can protect the top electrode and functional layer from physical or chemical damage by the light extraction material ink.
  • the thickness of the second interface layer may be 40 ⁇ 300 nm.
  • the material of the second interface layer can be selected from various metal oxides. In some embodiments, the transmittance of the above materials in the visible light region is greater than 80%, more preferably not less than 90%.
  • the material of the second interface layer can be selected from zinc oxide or zinc oxide doped with various metals, and the doping metal can be one or more of Mg, Al, etc., or ITO or molybdenum oxide, etc.
  • Fabrication of the second interfacial layer can be accomplished by curing with UV curable monomers and mixtures thereof.
  • the refractive index of the second interface layer is not lower than the refractive index of the top electrode (or the functional layer next to the top electrode), so as to ensure that the light of the light emitting layer can smoothly enter the light extraction layer.
  • the sub-pixel with the highest original external quantum efficiency (when the light extraction layer is not provided) is defined as the first sub-pixel, the sub-pixel with the lowest original external quantum efficiency is defined as the third sub-pixel, and the original external quantum efficiency is between the third sub-pixel.
  • the sub-pixel between the first sub-pixel and the third sub-pixel is the second sub-pixel; the external quantum efficiency improvement ratio of the light extraction layer to the first sub-pixel is X 1 , and the external quantum efficiency of the light extraction layer to the second sub-pixel is improved
  • the ratio is X 2
  • the external quantum efficiency improvement ratio of the light extraction layer to the third sub-pixel is X 3
  • Q 1 is the original external quantum efficiency of the corresponding sub-pixel,
  • Q 2 is the actual external quantum efficiency of the corresponding sub-pixel;
  • the lift ratio means that the light-emitting element keeps other conditions unchanged, and only increases the change of external quantum efficiency caused by the arrangement of the light extraction layer.
  • the light-emitting element may be an RGB (red, green, blue) light-emitting device, or an RGBW (red, green, blue, and white) light-emitting device.
  • RGB red, green, blue
  • RGBW red, green, blue, and white
  • the display panel when the display panel is not lit, the display panel presents the effect of being all black.
  • all-in-one black means that since ambient light is completely absorbed after entering the display panel, the display panel can be seen to be black as a whole when the display panel is not lit, without a gray effect.
  • one-piece black also includes other situations of one-piece black considered by those skilled in the art.
  • Top emission pixel substrate (the overall light-emitting area is 3*3mm, the light-emitting area is composed of 80*80 ⁇ m sub-pixel groups and a bank to prevent light mixing, and the overall aperture ratio is about 52%), and the reflective electrode is made of Ag with a thickness of 100nm and a thickness of 10nm.
  • the composition of ITO, the hole injection layer HIL is PEDOT:PSS with a thickness of 40nm, the hole transport layer HTL is TFB with a thickness of 30nm, the light-emitting layer EL is CdSe/ZnS red quantum dots with a thickness of 25nm, and the electron transport layer ETL is a thickness of 50nm.
  • the above-mentioned layers are all made by inkjet printing process, and the film layer is obtained by vacuum, heating, etc., under certain process conditions, vacuum sputtering mass ratio of 9:1 indium oxide/tin oxide mixed.
  • a high-purity ITO target was used to obtain an ITO top electrode with a thickness of 80 nm.
  • Nanoparticles (ie, light extraction particles) dispersion ie, light extraction particles
  • the self-made UV glue with a refractive index of 1.48 was diluted and dispersed with decane, the above-mentioned siloxane-modified TiO 2 solution was added, and after thorough mixing, a light extraction ink was obtained, and the total solid content of the UV glue and nanoparticles was 15wt%, Among them, the nanoparticles account for 70% of the total mass of the UV glue and the nanoparticles, and the UV glue accounts for 30% of the total mass of the UV glue and the nanoparticles.
  • Transmittance of the light extraction layer use the same formula and the same film-forming process to form a film on the transparent plain glass, use the UV-vis spectrophotometer UV-vis to take the plain glass as a reference, and deduct the background to obtain the light extraction transmittance of the layer.
  • External quantum efficiency use Keithley2400 power supply to provide voltage input to the light-emitting element and obtain the corresponding current output, and use integrating sphere (FOIS-1) combined with Ocean Optics spectrometer (QE-pro) to measure the brightness of the light-emitting element (the test object is a band with light-emitting element of circular polarizer).
  • the test structure is recorded in Table 2. According to the measured parameters such as current density and brightness, the external quantum efficiency of the light-emitting element can be obtained.
  • the initial brightness read by the instrument is 1000nit, but in fact the light-emitting element Its initial brightness is about 2000nit, that is, the life of the light-emitting element is obtained by testing under the condition of about 2000nit initial brightness.
  • Example 1 The same manufacturing process as in Example 1 was adopted, and the specific parameters are shown in Table 1.
  • Example 2 The difference from Example 1 is that an interface layer is also provided on the side of the light extraction layer away from the top emission pixel substrate, and a polystyrene (PS) interface layer with a thickness of 4.2 ⁇ m is obtained by printing with an inkjet printing device.
  • PS polystyrene
  • Example 1 The difference from Example 1 is that the light extraction layer is not provided.
  • Example 2 The difference from Example 1 is that the particle diameter of the light extraction particles is 300 nm.
  • the mass fraction in "light-extracting particles and their mass fraction" in Table 1 refers to the proportion of light-extracting particles in the total solid content, that is, the mass percentage of light-extracting particles in the cured light-extracting layer.
  • the flatness Ra of the light extraction layer in Example 7 is actually tested for the surface roughness of the PS interface layer.
  • Example 2 Example 3
  • Example 4 Example 5 External quantum efficiency 7.3% 7.2% 8.9% 7.9% 8.7% T95 life 81h 79h 113h 92.7h 104.9h Numbering Example 6
  • Example 7 Example 8 Comparative Example 1 Comparative Example 2 External quantum efficiency 9.9% 7.5% 6.7% 5.2% 9.3% T95 life 149h 89.6h 73.5h 50.1h 145.2h
  • the light-emitting element may also include an encapsulation layer. After the stacked layer of the thin film encapsulation is placed on the surface of the light extraction layer, the Ra value of the overall film layer will be further reduced, that is, the overall film layer will be further reduced. The flatness will be further improved, then after the circular polarizer is attached, the integrated black effect of the display panel will be better. Therefore, in order to show that the beneficial effect of the present disclosure really comes from the improvement of the light extraction layer, in the above embodiments and comparative examples Select the light-emitting element (or the light-emitting element with circular polarizer) as the object of the photoelectric performance test. From this, it can be seen that the display panel using the light-emitting element of the present disclosure has good display contrast, and can present the effect of integral black in the unlit state.
  • Example 2 small-sized nanoparticles are still used as light-extracting particles, and the mass fraction of nanoparticles is appropriately reduced, and UV glue with high refractive index is used, so that the overall refractive index of the light-extracting layer remains the same. Higher than the refractive index of the top electrode, a better light extraction effect is also achieved.

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Abstract

一种显示面板，包括防反射膜（7）和发光件，发光件包括基板（1）和设置在基板（1）一侧表面上的多个相互隔离的子像素，各子像素包括依次叠置的底电极（3）、功能层（4）、顶电极（5），至少部分子像素还包括光取出层（6），光取出层（6）设置在顶电极（5）的远离功能层（4）的一侧表面上，光取出层（6）内设有纳米粒子，纳米粒子的粒径不超过40nm。该显示面板具有高对比度的情况下实现了提升其使用寿命的效果。

Description

显示面板 技术领域
本公开涉及光电技术领域，具体而言，涉及一种显示面板。
背景技术
OLED(Organic Light Emitting Diode)显示装置由于具有快速响应、高对比度等特点，在显示市场中占据越来越多的份额。然而，OLED烧屏、寿命短等问题目前依然没有很好的解决方案。并且，此类电致发光器件的电极(一般有一侧的电极为金属)具有较强的反射性，会导致环境光被面板反射而射出，并与面板的自发光混合后造成显示面板的对比度下降，为了避免上述问题的发生，圆偏光片成为显示面板不可或缺的组件，但它的引入又会造成约一半的出光损失。同时，为了提升显示面板的使用寿命，高开口率的顶发射面板成为了本领域的研究重点。在顶发射显示面板的顶部设置封盖层(capping layer)成为提升其外量子效率的常规手段，但其提升比例依然十分有限。
另一方面，透镜型、散射型光取出结构对显示面板的出光效率有非常显著的提升，但是将它们结合圆偏光片使用时，圆偏光片对环境光反射的抑制效果会被破坏，即，在显示面板不点亮的情况下，透过圆偏光片去观察显示面板，不再能看到一体黑的“暗场”效果(一体黑的效果指的是环境光射入而不射出)，而是呈现一定的灰色，“暗场”效果被破坏会对显示面板的对比度造成极大的影响。
发明内容
本公开的目的在于提供一种显示面板，包括防反射膜和发光件，上述发光件包括基板和设置在上述基板一侧表面上的多个相互隔离的子像素，各上述子像素包括依次叠置的底电极、功能层、顶电极，至少部分上述子像素还包括光取出层，上述光取出层设置在上述顶电极的远离上述功能层的一侧表面上，上述光取出层内设有纳米粒子，上述纳米粒子的粒径不超过40nm。
可选地，上述光取出层含有的上述纳米粒子的质量分数≥70wt％。
可选地，上述光取出层含有的上述纳米粒子的质量分数≥50wt％，且上述光取出层包括聚合物基质，上述聚合物基质的折光指数大于1.65。
可选地，上述纳米粒子的粒径为5～30nm。
可选地，上述纳米粒子的折光指数≥1.8。
可选地，上述纳米粒子的表面为曲面。
可选地，上述纳米粒子选自氧化锌、氧化钛、五氧化二钽、氧化钇、氧化锆、氧化铝、氧化铌、氧化钨、氧化锑、氧化钒、氧化钼中的任一种或多种的组合。
可选地，上述光取出层的厚度为0.5～10μm。
可选地，上述光取出层的平整度Ra≤20nm。
可选地，在波长为550nm的光的照射下，上述光取出层的透过率不超过80％。
可选地，上述光取出层包括至少一种辅助材料，在可见光照射下，上述辅助材料的光透过率不低于80％。
可选地，上述光取出层中上述辅助材料的总的质量分数不超过30wt％，每种上述辅助材料的折光指数不小于1.4。
可选地，上述辅助材料包括界面修饰剂，上述界面修饰剂配位于上述纳米粒子的表面。
可选地，上述发光件还包括界面层，上述界面层设置在上述光取出层的远离上述基板的一侧表面上，在波长为550nm的光的照射下上述界面层的透过率不低于80％，上述界面层的折光指数≤1.8。
可选地，上述界面层的厚度为0.1～5μm。
可选地，定义原始外量子效率最高的上述子像素为第一子像素，原始外量子效率最低的上述子像素为第三子像素，原始外量子效率介于上述第一子像素和上述第三子像素之间的上述子像素为第二子像素；上述光取出层对上述第一子像素的外量子效率提升比为X 1，上述光取出层对上述第二子像素的外量子效率提升比为X 2，上述光取出层对上 述第三子像素的外量子效率提升比为X 3，上述X 1、上述X 2和上述X 3不相等，定义X n＝(Q 2-Q 1)/Q 1，其中，n选自1～3中的任一个自然数，Q 1为对应上述子像素的原始外量子效率，Q 2为对应上述子像素的实际外量子效率；上述X n≥0.5。
可选地，在上述显示面板未点亮状态下，上述显示面板呈现一体黑的效果。
应用本公开的技术方案，即通过采用纳米级小粒径粒子作为光取出粒子，在顶电极上方设置光取出层，大幅度提升显示面板的外量子效率，同时又不影响防反射膜的暗场效果呈现，因此，在保证显示面板具有高对比度的情况下，实现了提升其使用寿命的效果。
附图说明
构成本公开的一部分的说明书附图用来提供对本公开的进一步理解，本公开的示意性实施例及其说明用于解释本公开，并不构成对本公开的不当限定。在附图中：
图1示出了本公开一种实施例的显示面板的剖面结构示意图；
图2示出了本公开一种实施例的显示面板的剖面结构示意图；
图3示出了本公开一种实施例的显示面板的剖面结构示意图；
图4示出了本公开一种实施例的显示面板的剖面结构示意图；
图5为本公开的对比例2和实施例1、2、6、7、8的具有圆偏光片的发光件在未点亮状态下的照片，第一行从左到右依次对应对比例2、实施例1、实施例2，第二行从左到右依次对应实施例6、实施例7、实施例8(照片中的圆形为贴膜时导致的气泡)。
其中，上述附图包括以下附图标记：
1、基板；2、像素隔离结构；3、底电极；4、功能层；5、顶电极；6、光取出层；7、防反射膜；8、封装层；9、界面层。
具体实施方式
应该指出，以下详细说明都是例示性的，旨在对本公开提供进一步的说明。除非另有指明，本文使用的所有技术和科学术语具有与本公开所属技术领域的普通技术人员通常理解的相同含义。
需要说明的是，本公开的说明书和权利要求书中的术语“第一”、“第二”等是用于区别类似的对象，而不必用于描述特定的顺序或先后次序。应该理解这样使用的数据在适当情况下可以互换，以便这里描述的本公开的实施例。此外，术语“包括”和 “具有”以及他们的任何变形，意图在于覆盖不排他的包含，例如，包含了一系列步骤或单元的过程、方法、系统、产品或设备不必限于清楚地列出的那些步骤或单元，而是可包括没有清楚地列出的或对于这些过程、方法、产品或设备固有的其它步骤或单元。应当理解，在本公开中描述各层结构时，“在……上”或者“位于……上”的描述仅用于表示层与层之间的相对位置，并且可以包含直接接触以及非直接接触(即存在中间层)的情况。
现有技术中的透镜型、散射型光取出结构对显示面板的出光效率有非常显著的提升，但是将它们结合圆偏光片使用时，圆偏光片对环境光反射的抑制效果会被破坏。发明人研究发现，造成上述问题的主要原因是，圆偏光片与镜面反射结合才能起到一体黑的效果，而位于圆偏光片的靠近基板一侧的上述光取出结构或其它膜层、部件会破坏镜面反射，导致有部分光不能被圆偏光片吸收，从而会有部分光反射出来进入人眼。
本公开提供一种显示面板，包括防反射膜7和发光件，发光件包括基板1和设置在基板1一侧表面上的多个相互隔离的子像素，各子像素包括依次叠置的底电极3、功能层4、顶电极5，至少部分子像素还包括光取出层6，光取出层6设置在顶电极5的远离功能层4的一侧表面上，光取出层6内设有纳米粒子，纳米粒子的粒径不超过40nm。
本公开的技术方案通过采用纳米级小粒径粒子作为光取出粒子，在顶电极上方设置光取出层，当环境光射向显示面板时，大约一半的环境光先被防反射膜(例如圆偏光片)吸收，剩余的一半光在射出防反射膜并到达光取出层界面时，绝大部分光被该反射界面反射而又重新射向防反射膜，这部分反射的光的相位正好符合防反射膜的吸收方向，如此环境光就几乎全部被防反射膜吸收掉，从而降低了环境光对显示面板对比度的不良影响。因而大幅度提升显示面板的外量子效率，同时又不影响防反射膜的暗场效果呈现。在保证显示面板具有高对比度的情况下，实现了提升其使用寿命的效果。
需要注意的是，上述纳米粒子在光取出层中起到光取出粒子的作用，并且纳米粒子不具有光转换功能，同时光取出层不包括微米级的光取出粒子。上述纳米粒子的粒径指的是纳米粒子的平均粒径。防反射膜和发光件光学地连接，防反射膜可以位于发光件的正上方。
在一些实施例中，光取出层中的纳米粒子的粒径的偏差范围为正负25％以内，优选 正负10％以内。在粒径不超过40nm的前提下，粒径均匀性好的纳米粒子有利于得到平整性好的光取出层。
“至少部分子像素还包括光取出层6”是指至少部分顶电极5被光取出层6覆盖。
在一些实施例中，光取出层6为连续的一层，在另一些实施例中，光取出层6包括阵列排列的多个分隔的层。
在一些实施例中，上述发光件还包括设置在基板1上的多个像素隔离结构2(也称为bank)，以及像素隔离结构2限定形成的多个相互隔离的发光区域，上述多个子像素一一对应设置在多个发光区域中。
在一些实施例中，各子像素的功能层4可以包括依次叠置的电子注入层、电子传输层、发光层、空穴传输层和空穴注入层。
在另一些实施例中，发光件和防反射膜7平行地设置，可以有其他层(如封装层8)设置于发光件和防反射膜7之间。
在另一些实施例中，防反射膜7的外侧还设置其他结构，从而组成完整的显示面板。
在一些实施例中，显示面板包括封装层8，封装层8位于光取出层6的远离基板1的一侧。封装层一方面可以提高显示面板的阻水阻氧性能，另一方面，当封装层为薄膜封装时，薄膜封装的堆叠层设置到光取出层表面上后，可以起到使光取出层平坦化的作用。
在一些实施例中，显示面板还包括位于封装层8和防反射膜7之间的层。
在一些实施例中，光取出层6可以整面设置在顶电极5的表面上，如图3所示。这样有利于采用涂布工艺制备发光器件，制作方法简单。
在一些实施例中，显示面板中的防反射膜7为圆偏光片。防反射膜也可以选自本技术领域中和圆偏光片作用相同或相似的其它替代物。防反射膜起到不使环境光被面板反射而射出，并与面板的自发光混合造成显示面板的对比度下降的作用。
在一些实施例中，纳米粒子的粒径大于1nm但不超过3nm，或者不超过5nm，或者不超过7nm，或者不超过9nm，或者不超过13nm，或者不超过16nm，或者不超过19nm，或者不超过21nm，或者不超过24nm，或者不超过27nm，或者不超过29nm，或者不超过33nm，或者不超过36nm，或者不超过39nm。在一些实施例中，纳米粒子的粒径为5～30nm。在一些实施例中，纳米粒子的粒径为10～25nm。上述粒径可以保证 纳米粒子具有较高的折光指数和光取出效果。
在一些实施例中，光取出层6含有的纳米粒子的质量分数≥70wt％，或者≥75wt％，或者≥80wt％，或者≥85wt％，或者≥90wt％，或者≥95wt％。上述质量分数的纳米粒子可以保证光取出层的综合折光指数较高。综合折光指数＝∑(单组分的体积占比)*(单组份的折光指数值)。
在一些实施例中，光取出层6含有的纳米粒子的质量分数≥50wt％，或者≥55wt％，或者≥60wt％，或者≥65wt％，且光取出层包括聚合物基质，上述聚合物基质的折光指数大于1.65。
在一些实施例中，纳米粒子的折光指数≥1.8，或者≥2。
在一些实施例中，纳米粒子的表面为曲面，优选纳米粒子的形状为球形、类球形、椭球形或类椭球形。这样的纳米粒子的堆积平整性会更好。
在一些实施例中，纳米粒子可以选自氧化锌、氧化钛、五氧化二钽、氧化钇、氧化锆、氧化铝、氧化铌、氧化钨、氧化锑、氧化钒、氧化钼中的任一种或多种的组合，但不限于此。
在一些实施例中，光取出层6的厚度为0.5～10μm，或者0.8～3μm。
在一些实施例中，光取出层6的平整度Ra≤20nm，或者≤10nm，或者≤5nm。上述平整度可以保证光取出层具备良好的反射界面，从而进一步降低环境光对显示面板对比度的不良影响。
在一些实施例中，在波长为550nm的光的照射下，光取出层6的透过率不超过80％，或者不超过75％，或者不超过70％，或者不超过65％，或者不超过60％，或者不超过55％，或者不超过50％，或者不超过45％，或者不超过40％，或者不超过35％，或者不超过30％。可以观察到，上述实施例中的光取出层外观呈现一定的白度。
在一些实施例中，光取出层6可以不包括聚合物基质。纳米粒子和溶剂混合，然后添加到子像素区域内，待溶剂挥发后，即可形成光取出层。在一些实施例中，预先在纳米粒子表面修饰一些小分子界面修饰剂，以增加纳米粒子在溶剂中的分散性，当纳米粒子和溶剂混合，可以避免纳米粒子彼此团聚，从而施加到子像素区域后，光取出层由于粒子分散会相对均匀很多。
在另一些实施例中，光取出层6可以包括聚合物基质。聚合物基质主要起以下作用：一是分散纳米粒子，并通过聚合物基质将纳米粒子隔开从而起到稳定作用；二是 固定住纳米粒子，使其成为一个整体；三是这些聚合物基质还可以起到填充由纳米粒子堆积而产生的缝隙的作用，当聚合物基质的组分含量进一步提升后，就可以平坦化光取出层了，即缝隙都填满了，甚至还有余量覆盖住所有的纳米粒子。
在一些实施例中，光取出层6包括至少一种辅助材料，在可见光照射下，辅助材料的光透过率不低于80％，优选光透过率不低于90％。上述光透过率是指把实际光取出墨水配方中的辅助材料单独用于成膜时得到的膜的透过率，例如，光取出墨水的固含量为30wt％，辅助材料占3wt％，纳米粒子占27wt％，辅助材料的透过率近似为将这3％的辅助材料单独成膜，然后测试该膜在可见光(400～700nm)下的透过率。
在一些实施例中，光取出层6中辅助材料的总的质量分数不超过30wt％，每种辅助材料的折光指数不小于1.4。辅助材料可以保证整个光取出层的综合折光指数不会偏低。在保证光取出层整体的综合折光指数符合要求的前提下，辅助材料的折光指数与纳米粒子的折光指数差异越大越好，不同材质间的折光指数不同，有利于提升光取出效果。
在一些实施例中，光取出层中辅助材料可以是粘合剂、粘度调节剂、界面修饰剂、流变助剂等中的至少一种。粘合剂可以选自各种可固化树脂；粘度调节剂可以选自各种聚合物，例如PVK(聚(N-乙烯基咔唑))等；界面修饰剂可以是硅烷偶联剂或表面活性剂；流变助剂可以是流平剂、消泡剂等。任意一种辅助材料都需要满足尽可能吸光少、透过率高、无色透明的要求。
在一些实施例中，辅助材料包括界面修饰剂，界面修饰剂配位于纳米粒子的表面。界面修饰剂可以增加纳米粒子在溶剂中的分散性，当纳米粒子和溶剂混合，可以避免纳米粒子彼此团聚，从而施加到子像素区域后，光取出层会相对均匀很多。
在一些实施例中，发光件还包括界面层9(如第一界面层)，界面层9设置在光取出层6的远离基板1的一侧表面上，在波长为550nm的光的照射下，界面层的透过率不低于80％，界面层9的折光指数≤1.8，优选界面层9的折光指数不超过1.5且不小于1。界面层9的材料可以选自无机材料，通过物理气相沉积(溅射、蒸镀)或化学气相沉积(CVD)工艺制作；也可以选自有机材料，如各类树脂；也可以选自有机无机组合材料，如一层无机材料结合一层有机材料的堆叠结构，也可以是薄膜封装，其可以对发光件整体起到阻隔水氧的作用。在上述实施例中，界面层9的厚度为0.1～5μm。上述界面层可以起到提升光取出层平整度的作用，当环境光射向显示面板时，大约一半的环 境光先被防反射膜(例如圆偏光片)吸收，剩余的一半光在射出防反射膜后到达上述界面层的远离光取出层的一侧界面时，绝大部分光被该界面反射而又重新射向防反射膜，这部分反射的光的相位正好符合防反射膜的吸收方向，如此环境光就全部被防反射膜吸收掉了，从而可以进一步降低环境光对显示面板对比度的不良影响；另一方面，上述界面层可以起到保护光取出层的作用。
在一些实施例中，界面层9仅设置在发光区域的光取出层6的表面上，如图4所示。
在一些实施例中，界面层9设置在光取出层6的表面和顶电极5的裸露表面上，如图2所示。
在一些实施例中，发光件还包括第二界面层，第二界面层设置在顶电极和光取出层之间。第二界面层可以保护顶电极和功能层不受光取出材料墨水的物理或化学损伤。第二界面层的厚度可以为40～300nm。第二界面层的材料可以选自各种金属氧化物。在一些实施例中，上述材料在可见光区域内透过率大于80％，更优选不小于90％。例如，第二界面层的材料可以选自氧化锌或者各种金属掺杂的氧化锌，掺杂金属可以是Mg、Al等中的一种或多种，也可以是ITO或氧化钼等，还可以用UV可固化单体及其混合物，通过固化来实现第二界面层的制作。在一些实施例中，第二界面层的折光指数不低于顶电极(或紧挨顶电极的功能层)的折光指数，以保证发光层的光可以顺利射入到光取出层。
在一些实施例中，定义原始(未设置光取出层时)外量子效率最高的子像素为第一子像素，原始外量子效率最低的子像素为第三子像素，原始外量子效率介于第一子像素和第三子像素之间的子像素为第二子像素；光取出层对第一子像素的外量子效率提升比为X 1，光取出层对第二子像素的外量子效率提升比为X 2，光取出层对第三子像素的外量子效率提升比为X 3，X 1、X 2和X 3不相等，定义X n＝(Q 2-Q 1)/Q 1，其中，n选自1～3中的任一个自然数，Q 1为对应子像素的原始外量子效率，Q 2为对应子像素的实际外量子效率；X n≥0.5。提升比指的是发光件保持其他条件不变，仅增加设置光取出层带来的外量子效率变化。
在一些实施例中，上述发光件可以为RGB(红绿蓝)发光装置，也可以为RGBW(红绿蓝白)发光装置，针对不同发光颜色的子像素，设置有不同效率提取比例的光取出层，使不同发光颜色的子像素最终的外量子效率接近，实现同步老化，延长显示面板的使用寿命。
在一些实施例中，在显示面板未点亮状态下，显示面板呈现一体黑的效果。在一些实施例中，“一体黑”是指由于环境光射入显示面板后完全被吸收，从而在显示面板未点亮状态下肉眼可见其整体呈现黑色，而不会出现灰色的效果。在另一些实施例中，“一体黑”还包括本领域技术人员认为的其他一体黑的情况。
下面将结合具体实施例和对比例进一步介绍本公开的有益效果。
为了实验的简便，以下实施例并未制备成完整的显示面板，但本领域技术人员知悉如何形成完整的显示面板。
实施例1
1、发光件制作工艺：
顶发射像素基板(整体发光区域为3*3mm，发光区域由80*80μm的子像素群和防止混光的bank构成，整体开口率约为52％)，反射电极由厚度100nm的Ag和厚度10nm的ITO组成，空穴注入层HIL为厚度40nm的PEDOT:PSS，空穴传输层HTL为厚度30nm的TFB，发光层EL为厚度25nm的CdSe/ZnS红色量子点，电子传输层ETL为厚度50nm的ZnO纳米晶，上述各层均采用喷墨打印工艺制作，并经过真空、加热等方式得到所述膜层，在一定工艺条件下，真空溅射质量比9:1的氧化铟/氧化锡混合的高纯度ITO靶材，得到厚度80nm的ITO顶电极。
2、纳米粒子(即光取出粒子)分散：
在乙醇和乙酸体积比98:2的混合溶剂中，加入适量十二烷基三甲氧基硅烷并搅拌均匀，按硅氧烷：光取出粒子质量比1:10的比例添加粒径为40nm的TiO 2纳米粒子，保持搅拌一小时后，离心取下层沉淀，用乙醇多次洗涤并进行离心处理并适当干燥后，将其分散在癸烷中保存。
3、光取出墨水组成及制作工艺：
将自制的折光指数为1.48的UV胶用癸烷稀释分散后，加入上述硅氧烷修饰过的TiO 2溶液，充分混合后得到光取出墨水，UV胶和纳米粒子总的固含量为15wt％，其中，纳米粒子占UV胶和纳米粒子的总质量的70％，UV胶占UV胶和纳米粒子的总质量的30％。在惰性氛围中，在顶发射像素基板的顶电极上方设置上述光取出墨水，利用旋转涂布仪分步加速成膜的方式得到一定厚度的光取出湿膜，经UV固化(同时溶剂被除去)后形成光取出层，得到发光件；之后在光取出层表面直接贴合市售圆偏光片，并进行光电性能的测试(惰性氛围下进行)。
4、测试方法：
(1)光取出层透过率：利用相同配方、相同成膜工艺在透明素玻璃上成膜，用紫外-可见光分光光度计UV-vis以素玻璃为参照，将其背景扣除后得到光取出层的透过率。
(2)光取出层粗糙度：利用原子力显微镜AFM测试光取出层表面的粗糙度得到Ra值。
(3)外量子效率：采用Keithley2400电源给发光件提供电压输入并得到相应电流输出，采用积分球(FOIS-1)结合海洋光学的光谱仪(QE-pro)测定发光件的亮度(测试对象是带圆偏光片的发光件)。测试结构记录于表2。根据测定得到的电流密度与亮度等参数得到发光件的外量子效率，外量子效率越高，发光件性能越好，发光件寿命也可以得到相应的提升。
(4)寿命：以1000nit为亮度测试起点(即初始亮度)，恒定发光件的输入电流，实时记录发光件的亮度变化，并以发光件亮度衰减到初始值95％的值(1000nit*0.95＝950nit)定义为T95，即发光件亮度衰减到950nit后停止寿命测试。测试结构记录于表2。需要指出的是，这里的测试对象是带圆偏光片的发光件，由于市售圆偏光片对发光件出光有近50％的损耗，因此仪器读出的初始亮度为1000nit，但实际上发光件本身的初始亮度约为2000nit，即发光件的寿命是在初始亮度约2000nit条件下测试得到。
实施例2-6、8
采用实施例1相同的制作工艺，具体各参数见表1。
实施例7
与实施例1的区别在于：光取出层远离顶发射像素基板一侧还设置有界面层，利用喷墨打印设备打印得到厚度为4.2μm的聚苯乙烯(PS)界面层。
对比例1
与实施例1的区别在于：未设置光取出层。
对比例2
与实施例1的区别在于：光取出粒子的粒径为300nm。
表1
Figure PCTCN2022070887-appb-000001
Figure PCTCN2022070887-appb-000002
表1列举的相关物质折光指数n(@550nm处)参考值：实施例1、4、6、7、8和对比例2的UV胶为1.48，实施例2的UV胶为1.71；ZrO 2为2.17；TiO 2为2.65；ZnO为2.02；MoO 3为2.16；硅烷偶联剂约为1.42；solsperse(商用牌号)系列是一种高分子类分散剂，折光指数约为1.48；4-氨基-2-丁醇约为1.45；PVK约为1.68。表1的“光取出粒子及其质量分数”中的质量分数指的是光取出粒子在总固含量中的占比，即光取出粒子在固化后的光取出层中所占的质量百分数。实施例7的光取出层平整度Ra实际测试的是PS界面层的表面粗糙度。
表2
编号 实施例1 实施例2 实施例3 实施例4 实施例5
外量子效率 7.3％ 7.2％ 8.9％ 7.9％ 8.7％
T95寿命 81h 79h 113h 92.7h 104.9h
编号 实施例6 实施例7 实施例8 对比例1 对比例2
外量子效率 9.9％ 7.5％ 6.7％ 5.2％ 9.3％
T95寿命 149h 89.6h 73.5h 50.1h 145.2h
从图5可以明显看出，采用大尺寸(300nm)粒子作为光取出粒子的对比例2的发光件尽管有较好的光取出效果(即外量子效率提升显著)，但贴合圆偏光片后，一体黑效果被严重破坏，整体呈现灰色，极大影响显示对比度。图5示出的实施例1、2、6、7、8的光提取层中均采用粒径不超过40nm的纳米粒子作为光取出粒子，随着光取出层表面平整度Ra值的减小，一体黑的效果越显著。
需要说明的是，在实际的显示面板产品结构中，发光件还可以包括封装层，薄膜封装的堆叠层设置到光取出层表面后，膜层整体的Ra值会进一步减小，即膜层整体的平整性会进一步提升，那么贴合圆偏光片后，显示面板的一体黑的效果会更加好，因此为了表明本公开的有益效果确实来自于光取出层的改进，上述实施例和对比例中选择发光 件(或带有圆偏光片的发光件)作为光电性能测试的对象。由此可知，采用本公开的发光件的显示面板具有良好的显示对比度，在未点亮状态下能够呈现一体黑的效果。
结合表1和表2可以看出，在实施例1-7中，当光取出层的折光指数不低于顶电极(ITO折光指数为1.8)时，在上述光取出层的厚度区间，发光件的外量子效率提升的比例(与对比例1相比计算提升比例)与光取出层的厚度增加呈正比，相应地，发光件寿命也稳步提升。在实施例8中，尽管光取出层的厚度也相对合适，但由于光取出层的折光指数偏低，因此发光件的外量子效率的提升比例(与对比例1相比计算提升比例)低于其他实施例。值得一提的是，在实施例2中，仍然采用小粒径纳米粒子作为光取出粒子，并适当降低纳米粒子的质量分数，采用高折光指数的UV胶，使得光取出层整体的折光指数仍高于顶电极的折光指数，同样取得了较好的光取出效果。
以上所述仅为本公开的优选实施例而已，并不用于限制本公开，对于本领域的技术人员来说，本公开可以有各种更改和变化。凡在本公开的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本公开的保护范围之内。

Claims (17)

  1. 一种显示面板，其特征在于，包括防反射膜和发光件，所述发光件包括基板和设置在所述基板一侧表面上的多个相互隔离的子像素，各所述子像素包括依次叠置的底电极、功能层、顶电极，至少部分所述子像素还包括光取出层，所述光取出层设置在所述顶电极的远离所述功能层的一侧表面上，所述光取出层内设有纳米粒子，所述纳米粒子的粒径不超过40nm。
  2. 根据权利要求1所述的显示面板，其特征在于，所述光取出层含有的所述纳米粒子的质量分数≥70wt％。
  3. 根据权利要求1所述的显示面板，其特征在于，所述光取出层含有的所述纳米粒子的质量分数≥50wt％，且所述光取出层包括聚合物基质，所述聚合物基质的折光指数大于1.65。
  4. 根据权利要求1所述的显示面板，其特征在于，所述纳米粒子的粒径为5～30nm。
  5. 根据权利要求1或2所述的显示面板，其特征在于，所述纳米粒子的折光指数≥1.8。
  6. 根据权利要求1或2所述的显示面板，其特征在于，所述纳米粒子的表面为曲面。
  7. 根据权利要求6所述的显示面板，其特征在于，所述纳米粒子选自氧化锌、氧化钛、五氧化二钽、氧化钇、氧化锆、氧化铝、氧化铌、氧化钨、氧化锑、氧化钒、氧化钼中的任一种或多种的组合。
  8. 根据权利要求1或2所述的显示面板，其特征在于，所述光取出层的厚度为0.5～10μm。
  9. 根据权利要求1或2所述的显示面板，其特征在于，所述光取出层的平整度Ra≤20nm。
  10. 根据权利要求1或2所述的显示面板，其特征在于，在波长为550nm的光的照射下，所述光取出层的透过率不超过80％。
  11. 根据权利要求1或2所述的显示面板，其特征在于，所述光取出层包括至少一种辅助材料，在可见光照射下，所述辅助材料的光透过率不低于80％。
  12. 根据权利要求11所述的显示面板，其特征在于，所述光取出层中所述辅助材料的总的质量分数不超过30wt％，每种所述辅助材料的折光指数不小于1.4。
  13. 根据权利要求12所述的显示面板，其特征在于，所述辅助材料包括界面修饰剂，
    所述界面修饰剂配位于所述纳米粒子的表面。
  14. 根据权利要求1或2所述的显示面板，其特征在于，所述发光件还包括界面层，所述界面层设置在所述光取出层的远离所述基板的一侧表面上，在波长为550nm的光的照射下，所述界面层的透过率不低于80％，所述界面层的折光指数≤1.8。
  15. 根据权利要求14所述的显示面板，其特征在于，所述界面层的厚度为0.1～5μm。
  16. 根据权利要求1或2所述的显示面板，其特征在于，定义原始外量子效率最高的所述子像素为第一子像素，原始外量子效率最低的所述子像素为第三子像素，原始外量子效率介于所述第一子像素和所述第三子像素之间的所述子像素为第二子像素；所述光取出层对所述第一子像素的外量子效率提升比为X 1，所述光取出层对所述第二子像素的外量子效率提升比为X 2，所述光取出层对所述第三子像素的外量子效率提升比为X 3，所述X 1、所述X 2和所述X 3不相等，定义X n＝(Q 2-Q 1)/Q 1，其中，n选自1～3中的任一个自然数，Q 1为对应的所述子像素的原始外量子效率，Q 2为对应的所述子像素的实际外量子效率；所述X n≥0.5。
  17. 根据权利要求1或2所述的显示面板，其特征在于，在所述显示面板未点亮状态下，所述显示面板呈现一体黑的效果。
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