Brightness enhancement film and light-emitting device

Abstract

The utility model provides a brightness enhancement film and a light-emitting device, and relates to the technical field of display, the brightness enhancement film comprises a first composite film layer and a second liquid crystal polymer layer located on one side of the first composite film layer; the first composite film layer comprises a microporous structure and a first liquid crystal polymer arranged in the microporous structure; the second liquid crystal polymer layer comprises at least one sub-layer, and the sub-layer is provided with a plurality of spiral structures; wherein in the direction from the second liquid crystal polymer layer to the first composite thin film layer, the screw pitches of the multiple spiral structures change in a gradient mode. The brightness enhancement film can improve the light-emitting brightness of the light-emitting device, and also can give consideration to the brightness of a large visual angle, thereby improving the display effect.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a brightness enhancement film and a light-emitting device. Background Art

[0002] With the development of display technology, people's requirements for the image quality and performance of display products are becoming increasingly higher. The industry trend is to achieve a balance between low reflectivity and high light extraction efficiency. In related display products, polarizers are often used to reduce the reflection of ambient light. However, polarizers absorb a certain amount of display light, which significantly reduces the light extraction efficiency of the display product and results in poor display quality. Utility Model Content

[0003] The embodiments of the present application provide a brightness enhancement film and a light-emitting device; the brightness enhancement film can improve the brightness of the light-emitting device while also taking into account the brightness at a wide viewing angle, thereby improving the display effect.

[0004] The embodiments of this application adopt the following technical solutions:

[0005] In a first aspect, an embodiment of the present application provides a brightness enhancement film, comprising:

[0006] a first composite film layer, the first composite film layer comprising a microporous structure and a first liquid crystal polymer disposed in the microporous structure;

[0007] and a second liquid crystal polymer layer located on one side of the first composite film layer; the second liquid crystal polymer layer includes at least one sublayer, and the sublayer has a plurality of helical structures.

[0008] In some brightness enhancement films provided by embodiments of the present application, the pitches of the multiple helical structures vary gradually along the direction from the second liquid crystal polymer layer to the first composite film layer.

[0009] In some brightness enhancement films provided by embodiments of the present application, along the direction from the second liquid crystal polymer layer to the first composite film layer, the pitches of the multiple spiral structures in the same sub-layer gradually increase.

[0010] In some brightness enhancement films provided by embodiments of the present application, along a direction from the second liquid crystal polymer layer toward the first composite film layer, the pitches of the plurality of spiral structures in the second liquid crystal polymer layer gradually increase.

[0011] In some brightness enhancement films provided in the embodiments of the present application, the half pitch of the plurality of spiral structures ranges from 125 nm to 220 nm.

[0012] In some brightness enhancement films provided by embodiments of the present application, the second liquid crystal polymer layer includes one sub-layer, and the thickness of the second liquid crystal polymer layer is in the range of 0.5 μm to 50 μm.

[0013] In some brightness enhancement films provided by embodiments of the present application, the second liquid crystal polymer layer includes a first sublayer, a second sublayer, and a third sublayer arranged in sequence, and the first sublayer is in contact with the first composite film layer;

[0014] The half pitch of the multiple helical structures in the first sublayer ranges from 125 nm to 165 nm, the half pitch of the multiple helical structures in the second sublayer ranges from 155 nm to 195 nm, and the half pitch of the multiple helical structures in the third sublayer ranges from 185 nm to 220 nm.

[0015] The thickness of the first sublayer, the second sublayer and the third sublayer are all in the range of 0.5 μm to 5 μm.

[0016] In a second aspect, an embodiment of the present application provides a light-emitting device, comprising the brightness enhancement film as described in any one of the first aspects, further comprising:

[0017] substrate;

[0018] A first electrode, a light-emitting layer, a second electrode, an encapsulation layer, the brightness enhancement film and a polarizer are sequentially arranged on the substrate;

[0019] The second liquid crystal polymer layer in the brightness enhancement film is located on a side of the first composite film layer in the brightness enhancement film away from the polarizer.

[0020] An embodiment of the present application provides a brightness enhancing film and a light-emitting device, wherein the brightness enhancing film comprises: a first composite film layer, and a second liquid crystal polymer layer located on one side of the first composite film layer; the first composite film layer comprises a microporous structure and a first liquid crystal polymer arranged in the microporous structure; the second liquid crystal polymer layer comprises at least one sublayer, and the sublayer has multiple spiral structures; wherein, in the direction from the second liquid crystal polymer layer to the first composite film layer, the pitch of the multiple spiral structures changes gradiently.

[0021] In this way, when the brightness enhancement film is used in a light-emitting device, since the second liquid crystal polymer layer has multiple spiral structures, the spiral structure can transmit circularly polarized light in a specific band and reflect circularly polarized light in other bands. The circularly polarized light in the reflected band can be reflected by the reflective electrode in the light-emitting device and then emitted after passing through the spiral structure and the first composite film layer, thereby greatly improving the light extraction efficiency of the light-emitting device; in addition, when the light passes through the interface between the microporous structure in the first composite film layer and the first liquid crystal polymer, refraction or scattering occurs, causing part of the light to be emitted from the wide viewing angle (side viewing angle) of the light-emitting device, thereby taking into account the improvement of the wide viewing angle brightness of the light-emitting device.

[0022] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 A schematic structural diagram of a brightness enhancement film provided in an embodiment of the present application; wherein, Figure 1 Figure (1) is a schematic structural diagram of a brightness enhancement film including a first composite film layer and a second liquid crystal polymer layer. Figure 1 Figure (2) is a schematic diagram of the microstructure of the first composite film layer. Figure 1 Figure (3) is a schematic diagram of the microstructure of the second liquid crystal polymer layer;

[0025] Figure 2A A schematic diagram of a rotating structure provided in an embodiment of the present application;

[0026] Figure 2B A schematic diagram of a multi-layer liquid crystal structure provided in an embodiment of the present application;

[0027] Figure 3 A schematic cross-sectional structure diagram of a second liquid crystal polymer having a multilayer structure provided in an embodiment of the present application;

[0028] Figures 4 to 6 Schematic diagram of the structures of three light-emitting devices provided in the embodiments of the present application. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0030] In the embodiments of the present application, words such as "first", "second", "third", and "fourth" are used to distinguish between identical or similar items with basically the same functions and effects. This is only for the purpose of clearly describing the technical solutions of the embodiments of the present application, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0031] In the embodiments of the present application, the terms "upper" and "lower" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0032] Throughout the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of the present application. Schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be included in any one or more embodiments or examples in any suitable manner.

[0033] In the embodiments of the present application, “a plurality of” means two or more, and “at least one” means one or more, unless otherwise clearly defined.

[0034] The features "parallel," "perpendicular," and "identical" used in the embodiments of the present application include features such as "parallel," "perpendicular," and "identical" in the strict sense, as well as "approximately parallel," "approximately perpendicular," and "approximately identical" that include certain tolerances, taking into account the measurement and tolerances associated with the measurement of a particular quantity (e.g., limitations of the measurement system), and represent within an acceptable range of deviation for a particular value determined by a person of ordinary skill in the art. For example, "approximately" can mean within one or more standard deviations, or within 3% or 5% of the stated value.

[0035] Unless the context requires otherwise, throughout the specification and claims, the term "comprising" is to be construed in an open, inclusive sense, that is, meaning "including, but not limited to."

[0036] The polygons in this specification are not in a strict sense, and may be approximate triangles, parallelograms, trapezoids, pentagons or hexagons, etc., and may have some small deformations due to tolerances.

[0037] With the development of display technology, people have increasingly higher requirements for the image quality and performance of display products. Among them, the industry trend is to achieve a balance between low reflectivity and high light extraction efficiency. In related OLED (Organic Light Emitting Diode) display products, polarizers are typically used to reduce ambient light reflection. However, polarizers have low transmittance and can absorb a certain amount of display light, which seriously reduces the light extraction efficiency of the display product and thus poor display quality.

[0038] In order to improve the above problems, the current solution is as follows: using COE (Color filter On Encapsulation) technology, that is, by constructing a black matrix and color filter (BM and RGB Color-filter) on the light-emitting side of the OLED device, eliminating the polarizer. This can improve the light-emitting efficiency and reduce power consumption by about 25%. However, its reflectivity of ambient light is not as low as that of a polarizer, and its use effect needs to be further improved, and its usage scenarios are limited.

[0039] Based on this, an embodiment of the present application provides a brightness enhancement film that can increase the brightness of light emitted by a light-emitting device while also taking into account the brightness at a wide viewing angle, thereby improving the display effect.

[0040] Specifically, such as Figure 1 As shown in Figures (1), (2) and (3), the brightness enhancement film 8 includes: a first composite film layer 81, and a second liquid crystal polymer layer 82 located on one side of the first composite film layer 81; the first composite film layer 81 includes Figure 1 The microporous structure shown by the arrow in Figure (2) and the microporous structure ( Figure 1 The first liquid crystal polymer LC in the second liquid crystal polymer layer 82 includes at least one sublayer, and each sublayer has a plurality of helical structures.

[0041] in, Figure 1 Figure (2) is Figure 1 The microstructure diagram of the first composite film layer 81 in Figure (1) is shown. Figure 1 Figure (3) is Figure 1 Schematic diagram of the microstructure of the second liquid crystal polymer layer 82 in Figure (1).

[0042] exist Figure 1In the figure, the position marked Bottom is the side where the light enters, and the position marked Top is the side where the light exits.

[0043] In an exemplary embodiment, the first composite film layer 81 includes a microporous structure formed of a polymer. In some examples, the microporous structure has a plurality of holes. The holes can be independently arranged or connected to each other.

[0044] Figure 1 In the schematic diagram drawn in Figure (2), polymerized liquid crystal (first liquid crystal polymer LC) is set in the hole, so LC (Liquid Crystal) is marked at the hole position for illustration.

[0045] Exemplarily, the size of the pores in the microporous structure is less than or equal to 2 μm. For example, the size of some pores ranges from 1 μm to 2 μm, and the size of some pores ranges from 0.3 μm to 1.5 μm.

[0046] In some areas of the first composite film layer 81, the first liquid crystal polymer LC completely fills the microporous structure, so that the first liquid crystal polymer LC is in direct contact with the pore walls of the microporous structure; in other areas of the first composite film layer 81, the first liquid crystal polymer LC does not completely fill the microporous structure, so that there is still a gap between the first liquid crystal polymer LC and the pore walls of the microporous structure.

[0047] Since the first composite film layer 81 includes a microporous structure formed by a high molecular polymer, and Figure 1 The first liquid crystal polymer LC within the microporous structure (not labeled) is shown. Whether the first liquid crystal polymer LC is in direct contact with the pore walls of the microporous structure or there are gaps between them, multiple interfaces exist within the first composite film layer 81, such as the interface between the first liquid crystal polymer LC and the pore walls of the microporous structure, the solid-gas interface between the first liquid crystal polymer LC and the gaps, or the solid-gas interface between the gaps and the pore walls of the microporous structure. When display light passes through various interfaces within the first composite film layer 81, it can be refracted or scattered, allowing it to be emitted not only from the front viewing angle but also from the side viewing angle. This improves the light intensity at the side viewing angle, thereby alleviating the problem of rapid brightness decay at wide viewing angles in the light-emitting device.

[0048] In an exemplary embodiment, the second liquid crystal polymer layer 82 includes one sub-layer, and the thickness of the second liquid crystal polymer layer is in a range of 0.5 μm to 50 μm.

[0049] Illustratively, the thickness of the second liquid crystal polymer layer 82 may be 0.6 μm, 1.0 μm, 1.8 μm, 2.5 μm, 3.5 μm, 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 20 μm, 22 μm, 25 μm, 35 μm, 38 μm, 40 μm, 42 μm, 45 μm or 48 μm.

[0050] After polymerization, the cholesteric liquid crystal molecules form a stable polymer film.

[0051] In an exemplary embodiment, the second liquid crystal polymer layer 82 includes a plurality of sub-layers, each of which has a thickness ranging from 0.5 μm to 5 μm. For example, the thickness of each sub-layer may be 0.6 μm, 0.7 μm, 0.8 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.8 μm, 2.5 μm, 3.5 μm, 4.2 μm, 4.5 μm, or 4.8 μm.

[0052] The second liquid crystal polymer layer 82 includes cholesteric liquid crystal molecules, such as Figure 2B As shown, this type of liquid crystal molecules are flat and arranged in layers. The molecules in the layer are parallel to each other, and the long axis of the molecules is parallel to the layer plane. Figure 2A As shown, the angles of the molecular long axes of different layers vary slightly, and the layers are stacked along the normal direction of the layer as shown in Figure 2A The spiral structure shown.

[0053] like Figure 2A and Figure 2B As shown in Figure 1, the orientation of the liquid crystal molecules in each layer of cholesteric liquid crystal is slightly twisted from that of the adjacent layers, typically by about 15°. The layers are stacked to form a helical structure. The molecular orientation returns to its original state after a 360° rotation. The minimum distance P between two layers of liquid crystal molecules with the same orientation is called the helical pitch.

[0054] Cholesteric liquid crystals (CLCs) are molecules that self-assemble into a helical structure and exhibit the ability to reflect circularly polarized light within a specific wavelength range. This is because the helical pitch of the liquid crystal is very sensitive to temperature. When the helical pitch P matches the wavelength of light, the helical structure produces a selective light reflection phenomenon.

[0055] After the cholesteric liquid crystal molecules are polymerized to form a polymer film (for example, the second liquid crystal polymer layer 82), in a system composed of achiral monomers, or a combination of achiral monomers and chiral monomers, the helical structure is retained during the polymerization process, while in a system composed only of chiral monomers, the helical structure may be destroyed by polymerization.

[0056] In the embodiment of the present application, when the brightness enhancement film is used in a light-emitting device, since the second liquid crystal polymer layer 82 has multiple spiral structures, the spiral structure can transmit circularly polarized light of a specific band and reflect circularly polarized light of other bands. The circularly polarized light of the reflected band can be reflected by the reflective electrode in the light-emitting device and then pass through the spiral structure and the first composite film layer 81 in turn and then be emitted, thereby greatly improving the light extraction efficiency of the light-emitting device; in addition, when the light passes through multiple interfaces in the first composite film layer 81, refraction or scattering can occur, so that part of the light is emitted from the wide viewing angle direction (side viewing angle) of the light-emitting device, thereby taking into account the improvement of the wide viewing angle brightness of the light-emitting device.

[0057] In some brightness enhancement films provided in the embodiments of the present application, such as Figure 1 As shown in FIG. (3), along the direction from the second liquid crystal polymer layer 82 to the first composite film layer 81, the pitches P (including P1 and P2) of the multiple helical structures change in a gradient.

[0058] In the embodiments of the present application, by controlling the intensity and direction of light during the preparation of the second liquid crystal polymer layer 82, the pitches P (including P1 and P2) of the multiple helical structures in the second liquid crystal polymer layer 82 can be controlled to vary in a gradient. This allows different regions along the thickness of the same second liquid crystal polymer layer 82 to transmit and reflect circularly polarized light of different wavelengths, thereby enabling the same second liquid crystal polymer layer 82 to improve the light extraction efficiency of different color display lights. For example, the same second liquid crystal polymer layer 82 can simultaneously improve the light extraction efficiency of red, green, and blue display lights.

[0059] For example, in Figure 1 In FIG. (3), along the direction from the second liquid crystal polymer layer 82 to the first composite film layer 81, the pitch of the multiple spiral structures in the second liquid crystal polymer layer 82 gradually increases, for example, the pitch P1 is greater than the pitch P2.

[0060] In some brightness enhancement films 8 provided in the embodiments of the present application, the pitch P of the multiple helical structures in the same sub-layer gradually increases along the direction from the second liquid crystal polymer layer 82 to the first composite film layer 81 .

[0061] For example, when the second liquid crystal polymer layer 82 includes multiple sublayers, the pitch P of multiple spiral structures in the same sublayer gradually increases, but the pitch P of multiple spiral structures in two adjacent sublayers does not necessarily follow a pattern of gradually increasing, and can be specifically designed according to the number of sublayers and the thickness of the sublayers.

[0062] In some brightness enhancement films provided in the embodiments of the present application, the half pitch P of the plurality of spiral structures ranges from 125 nm to 220 nm.

[0063] For this type of helical structure, since half the pitch P of the helical structure can be directly measured by optical means, half the pitch P is used in this specification to define the characteristics of the helical structure.

[0064] Illustratively, the half pitch P of the plurality of helical structures may be 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 195 nm, 200 nm, 210 nm, or 215 nm.

[0065] In some brightness enhancement films provided by the embodiments of the present application, the second liquid crystal polymer layer 82 includes a first sublayer, a second sublayer, and a third sublayer arranged in sequence, and the first sublayer is in contact with the first composite film layer 81;

[0066] Among them, the half pitch of multiple helical structures in the first sublayer ranges from 125nm to 165nm, the half pitch of multiple helical structures in the second sublayer ranges from 155nm to 195nm, and the half pitch of multiple helical structures in the third sublayer ranges from 185nm to 220nm.

[0067] For example, the first sublayer may be a film layer mainly used to improve the brightness of red light, the second sublayer may be a film layer mainly used to improve the brightness of green light, and the third sublayer may be a film layer mainly used to improve the brightness of blue light.

[0068] Exemplarily, the first sublayer is mainly used to improve the brightness of red light, but may also improve the brightness of green light or blue light, but the improvement effect on red light is the most significant.

[0069] In practical applications, since the wavelength of red light is greater than the wavelength of green light and greater than the wavelength of blue light, when the first sublayer is mainly used to increase the brightness of red light, the second sublayer is mainly used to increase the brightness of green light, and the third sublayer is mainly used to increase the brightness of blue light, the first sublayer needs to transmit light in the high wavelength band and reflect light in the low wavelength band; the third sublayer needs to transmit light in the low wavelength band and reflect light in the high wavelength band; the second sublayer is in the middle; the pitch range of the spiral structure is equivalent to the wavelength band of the reflectable light, so in some cases, half the pitch of multiple spiral structures in the first sublayer can be set to be less than or equal to half the pitch of multiple spiral structures in the second sublayer, and half the pitch of multiple spiral structures in the second sublayer can be less than or equal to half the pitch of multiple spiral structures in the third sublayer.

[0070] Exemplarily, the thickness of the first sub-layer, the second sub-layer and the third sub-layer are all in the range of 0.5 μm to 5 μm.

[0071] For example, the thickness of the first, second and third sublayers may be 0.8 μm, 1.0 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2.0 μm, 2.3 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.3 μm, 4.5 μm or 4.8 μm.

[0072] In some embodiments, the first sub-layer, the second sub-layer, and the third sub-layer have the same thickness.

[0073] In some embodiments, the thicknesses of the first sub-layer, the second sub-layer, and the third sub-layer are not exactly the same.

[0074] In some brightness enhancement films provided in the embodiments of the present application, such as Figure 3 As shown, an adhesive layer (OCA) is provided between the first sublayer (eg, R-CLC) and the second sublayer (eg, G-CLC), and between the second sublayer (eg, G-CLC) and the third sublayer (eg, B-CLC).

[0075] For example, the material of the bonding layer may be optical adhesive.

[0076] In the embodiments of the present application, by providing an adhesive layer between the multiple sub-layers, the adhesion between the multiple sub-layers can be greatly improved, thereby improving the mechanical strength and stability of the optical film.

[0077] In some brightness enhancement films provided in the embodiments of the present application, the second liquid crystal polymer layer 82 includes a second liquid crystal polymer, which is polymerized by at least one nematic liquid crystal monomer, at least one chiral additive and at least one reaction aid; wherein the content of the nematic liquid crystal monomer is 50wt% to 90wt%, the content of the chiral additive is 5wt% to 30wt%, and the content of the reaction aid is 2wt% to 10wt%.

[0078] After the cholesteric liquid crystal molecules are polymerized to form a polymer film (e.g., second liquid crystal polymer layer 82), the helical structure is retained during the polymerization process in a system composed of achiral monomers, or a combination of achiral and chiral monomers. In an embodiment of the present application, by configuring the second liquid crystal polymer to be polymerized from at least one nematic liquid crystal monomer, at least one chiral additive, and at least one reaction aid, the helical structure is retained after polymerization, thereby providing the second liquid crystal polymer layer 82 with more stable optical properties.

[0079] In some brightness enhancement films provided in the embodiments of the present application, the first composite film layer 81 is formed by polymerizing a non-liquid crystal monomer R10-X-R11, a nematic liquid crystal monomer, and a photoinitiator; wherein the content of the non-liquid crystal monomer R10-X-R11 is 5wt% to 50wt%, the content of the nematic liquid crystal monomer is 50wt% to 9wt%, and the content of the photoinitiator is 2wt% to 10wt%;

[0080] Among them, one of R10 and R11 is acrylate or methacrylate, and the other is methyl, cyano, halogen, ethyl formate or hydrogen; and X is a flexible alkyl or alkoxy group.

[0081] For example, the photoinitiator includes at least one of Irg184 (1-hydroxycyclohexyl phenyl ketone) and Irg651 (benzoin diethyl ether).

[0082] Among them, the chemical structures of Irg184 (1-hydroxycyclohexyl phenyl ketone) and Irg651 (benzoin diethyl ether) are as follows:

[0083]

[0084] In some brightness enhancement films provided by embodiments of the present application, the nematic liquid crystal monomer in the component system of the first composite film layer 81 and the second liquid crystal polymer layer 82 includes at least one of the following structural formulas 1 and 2:

[0085] Structural formula 1,

[0086]

[0087] Structural formula 2,

[0088]

[0089] Among them, R1 is methyl, cyano, halogen, ethyl formate or hydrogen, R2, R3 and R4 are all selected from acrylate or methacrylate, R5 is an alkane group, alkoxy group, aromatic group or heterocyclic structure, A1, A2, A3 are all selected from flexible alkane group, alkoxy group, aromatic group or heterocyclic structure, and B1 and B2 are both selected from cyclohexane, aromatic group or heterocyclic structure.

[0090] For example, the above structural formula 1 may include the following specific structure:

[0091]

[0092] For example, the above structural formula 2 may include the following specific structure:

[0093]

[0094] In some brightness enhancement films provided in the embodiments of the present application, the chiral additives include: And the following structural formula 3,

[0095]

[0096] Among them, R6~R9 are all selected from acrylate group, methacrylate group or hydrogen; A4~A7 are alkane group, alkoxy group, ester group, aromatic group or heterocyclic structure; B3 is selected from cholesterol, isosorbide, helical binaphthyl or asymmetric carbon atom.

[0097] For example, the specific structure of the chiral additive may include:

[0098]

[0099] The reaction aids include a photoinitiator and a light absorber; wherein the photoinitiator includes 1-hydroxycyclohexyl phenyl ketone and benzoin diethyl ether; the light absorber includes 2-hydroxy-4-n-octyloxybenzophenone (UV531) and 2-[2-hydroxy-3,5-bis(1,1-dimethylpropylphenyl)]-2H-benzotriazole (UV328).

[0100] Among them, the chemical structures of Irg184 (1-hydroxycyclohexyl phenyl ketone) and Irg651 (benzoin diethyl ether) are as follows:

[0101]

[0102] The chemical structures of light absorbers UV328 and UV531 are as follows:

[0103]

[0104] The embodiment of the present application provides a light emitting device, such as Figure 6 As shown, comprising a brightness enhancement film 8 (BEF) as any one of the above, further comprising:

[0105] Substrate 1 (Substrate);

[0106] A first electrode 2, a light-emitting layer 4, a second electrode 6, an encapsulation layer 7, a brightness enhancement film 8 and a polarizer 9 are sequentially arranged on a substrate 1;

[0107] The second liquid crystal polymer layer 82 in the brightness enhancement film 8 is located on a side of the first composite film layer 81 in the brightness enhancement film 8 away from the polarizer 9 .

[0108] Exemplarily, the encapsulation layer 7 includes three sublayers, namely inorganic sublayer / organic sublayer / inorganic sublayer, wherein the materials used for the inorganic sublayer are SiNx, SiOx, etc., and the thickness of each inorganic sublayer ranges from 0.4 to 1.6 μm. The materials used for the organic sublayer are polymers such as acrylates and epoxies, and the thickness of the organic sublayer ranges from 6 to 12 μm.

[0109] Illustratively, the first composite film layer 81 may be in contact with the polarizer 9 .

[0110] For example, Figure 6 As shown, the light-emitting device further includes a hole transport layer 3 and an electron transport layer 5 .

[0111] In an exemplary embodiment, the light-emitting device may be an organic light-emitting diode (OLED); or, the light-emitting device may be a quantum dot light-emitting diode (QD LED).

[0112] It should be noted that the embodiments of the present application are described using an OLED as an example of a light-emitting device. For example, the light-emitting device may be an OLED (Organic Light Emitting Diode), such as an OLED device including three colors of RGB; or, the light-emitting device may be a WOLED (White Organic Light Emitting Diode).

[0113] In some embodiments, as Figure 4 As shown, the OLED light emitting device may include a single light emitting layer (one EL unit); in other embodiments, as shown in FIG. Figure 5 As shown, the OLED light-emitting device can include a double-layer light-emitting layer (two EL units) with a charge generation layer (CGL) added between the double-layer light-emitting layers to achieve a double-layer light-emitting (Tandem EL) design. Of course, it can also include a triple-layer light-emitting layer (three EL units) with a charge generation layer (CGL) added between any two adjacent light-emitting layers.

[0114] The above-mentioned OLED light-emitting device not only includes a film layer that directly emits light, but also includes functional film layers for auxiliary light emission, such as: a hole transport layer 3, an electron transport layer 5, a hole injection layer and an electron injection layer.

[0115] Exemplarily, the material used for the light-emitting layer 4 may include one or more fluorescent materials, phosphorescent materials or thermally activated delayed fluorescent materials, the fluorescent materials include DCM, DCJ, Alq3 and DPVPi, the phosphorescent materials include Pt7O7, PtOEP, FirPic and Ir(ppy)3, and the thermally activated delayed fluorescent materials include DACR-DPTX, TPA-DMAC and 4CzIPN.

[0116] For example, the material of the light-emitting layer 4 can be selected from pyrene derivatives, anthracene derivatives, fluorene derivatives, perylene derivatives, styrylamine derivatives, metal complexes, and the like.

[0117] For example, the charge generation layer (CGL) may be an inorganic / inorganic stack, such as Li / Ca / Ag, LiF / Al / Au, and Al / WO3 / Au, or an inorganic / organic stack, such as Alq3(Bphen or BCP):Li / Bphen:Rb2CO3 and LiF / ZnPc:C60 / MoO3, etc. The charge generation layer (CGL) may also be made of the following materials, such as Alq3:Li(or Bphen:Li) / HAT-CN, F 16 CuPc / CuPc and Li: Bphen / Al / F4-TCNQ / HAT-CN.

[0118] Exemplarily, the material of the hole injection layer may include oxides, such as molybdenum oxide, titanium oxide, vanadium oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide, tantalum oxide, silver oxide, tungsten oxide, and manganese oxide.

[0119] For example, the material of the hole injection layer may also include organic materials, such as hexacyanohexaazatriphenylene, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), and 1,2,3-tris[(cyano)(4-cyano-2,3,5,6-tetrafluorophenyl)methylene]cyclopropane.

[0120] Exemplary materials of the hole transport layer may include aromatic amines and dimethylfluorene or carbazole materials having hole transport properties, such as: 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (TPD), 4-phenyl-4'-(9-phenylfluorene-9-yl)triphenylamine (BAFLP), 4,4'-bis[N-(9,9-dimethylfluorene-2-yl)-N-phenylamino]biphenyl (DFLDPBi), 4,4'-di(9-carbazolyl)biphenyl (CBP), 9-phenyl-3-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (PCzPA).

[0121] For example, the material of the electron transport layer may include aromatic heterocyclic compounds, such as benzimidazole derivatives, imidazole derivatives, pyrimidine derivatives, oxazine derivatives, quinoline derivatives, isoquinoline derivatives, phenanthroline derivatives, and the like.

[0122] For example, the material of the electron injection layer may be an alkali metal or a metal and a compound thereof, such as lithium fluoride (LiF), ytterbium (Yb), magnesium (Mg), and calcium (Ca).

[0123] In the embodiment of the present application, when the brightness enhancement film is used in a light-emitting device, since the second liquid crystal polymer layer 82 has multiple spiral structures, the spiral structure can transmit circularly polarized light of a specific band and reflect circularly polarized light of other bands. The circularly polarized light of the reflected band can be reflected by the reflective electrode in the light-emitting device and then pass through the spiral structure and the first composite film layer 81 in turn and then be emitted, thereby greatly improving the light extraction efficiency of the light-emitting device; in addition, when the light passes through multiple interfaces in the first composite film layer 81, refraction or scattering can occur, so that part of the light is emitted from the wide viewing angle direction (side viewing angle) of the light-emitting device, thereby taking into account the improvement of the wide viewing angle brightness of the light-emitting device.

[0124] An embodiment of the present application provides a display panel, which includes the light-emitting device as described above.

[0125] The type of the display panel is not limited; the display panel may be a flexible display panel (ie, bendable or foldable), or the display panel may be a rigid display panel.

[0126] The display panel may be an OLED (Organic Light Emitting Diode) display panel. OLED display panels have advantages such as simple manufacturing process, low cost, low power consumption, high brightness, wide operating temperature range, thin size, fast response speed, and easy color and large-screen display, and have broad application prospects.

[0127] The display panel provided by the embodiments of the present application has the advantages of high light extraction efficiency, low power consumption, and slow brightness decay at a wide viewing angle.

[0128] An embodiment of the present application provides a method for preparing a brightness enhancement film, which is used to prepare any of the brightness enhancement films described above, and the method comprises:

[0129] S81, providing a substrate;

[0130] For example, the substrate may include a substrate, a first electrode (eg, an anode) on the substrate, a hole transport layer, a light emitting layer, an electron transport layer, a second electrode (eg, a cathode), and an encapsulation layer.

[0131] S82, forming a second liquid crystal polymer layer 82 on the substrate; the second liquid crystal polymer layer 82 includes at least one sublayer, and the sublayer has a plurality of helical structures; wherein the pitches of the plurality of helical structures vary gradually along the direction from the second liquid crystal polymer layer 82 to the first composite film layer 81;

[0132] The second liquid crystal polymer layer 82 is a polymer film formed by polymerizing at least one nematic liquid crystal monomer, at least one chiral additive, and at least one reaction aid.

[0133] In the actual preparation process, at least one nematic liquid crystal monomer, at least one chiral additive, and at least one reaction aid are mixed in the aforementioned proportions to form a uniform mixed crystal, referred to as a polymer precursor. This polymer precursor is polymerized under ultraviolet irradiation or heating for a predetermined time to form the second liquid crystal polymer layer 82.

[0134] This specification takes ultraviolet light irradiation polymerization as an example to prepare the second liquid crystal polymer layer 82 .

[0135] When the second liquid crystal polymer layer 82 includes a sublayer, the above-mentioned polymer precursor can be treated by ultraviolet irradiation from the upper surface, so that the mixed crystal is polymerized into a polymer film, i.e., the second liquid crystal polymer layer 82; since the irradiation intensity of ultraviolet light in the same sublayer decreases from the surface to the bottom, the pitch of the spiral structure in the obtained second liquid crystal polymer layer 82 shows a gradient change of decreasing size from the surface to the bottom.

[0136] In addition, step-by-step polymerization can be used to prepare a sublayer with a pitch gradient change, for example, the above-mentioned polymerization precursor is irradiated with a first irradiation intensity for a fixed time; and then the above-mentioned polymerization precursor is irradiated with a second irradiation intensity for a fixed time; wherein the second irradiation intensity is greater than the first irradiation intensity, so that the irradiation intensity received by the surface of the obtained polymer film is greater than that of the bottom layer, which is conducive to forming a trend of the pitch becoming smaller and smaller from the surface layer to the bottom layer.

[0137] Exemplarily, the specific method of preparing the second liquid crystal polymer layer 82 by step-by-step polymerization is as follows:

[0138] The first step is to use UV polymerization with an irradiation intensity of 0.01 to 0.5 mW / cm 2 , polymerization time 10~30min, polymerization temperature 5~30℃;

[0139] The second step is to use UV polymerization with an irradiation intensity of 5 to 15 mW / cm 2 , polymerization time 2 to 10 minutes, polymerization temperature 20 to 60°C.

[0140] S83 , forming a first composite thin film layer 81 on the second liquid crystal polymer layer 82 to obtain a brightness enhancement film.

[0141] The first composite film layer 81 is formed by polymerization of non-liquid crystal monomers R10-X-R11, nematic liquid crystal monomers and a photoinitiator.

[0142] In the actual preparation process, a uniform prepolymer is formed by mixing the non-liquid crystal monomer R10-X-R11, the nematic liquid crystal monomer and the photoinitiator in the proportions described above. The prepolymer is polymerized under ultraviolet irradiation or heating conditions for a preset time to obtain the first composite film layer 81.

[0143] For example, the first composite film layer 81 may be prepared by step-by-step polymerization, as exemplified below:

[0144] The first step is to use UV polymerization with an irradiation intensity of 0.01 to 0.5 mW / cm 2 , polymerization time 0.5~2min, polymerization temperature 5~30℃;

[0145] The second step is to use UV polymerization with an irradiation intensity of 5 to 15 mW / cm 2 , polymerization time 2 to 10 minutes, polymerization temperature 20 to 60° C., to obtain the first composite film layer 81.

[0146] Specifically, in some embodiments, the first composite film layer 81 can be prepared by a step-by-step polymerization method. For example, the first step of ultraviolet irradiation intensity is 0.1 mW / cm 2 , polymerization time 1min, polymerization temperature 25℃, second step UV irradiation intensity 10mW / cm2 , polymerization time 5min, polymerization temperature 25℃.

[0147] When the brightness enhancement film prepared in the embodiment of the present application is used in a light-emitting device, since the second liquid crystal polymer layer 82 has multiple spiral structures, the spiral structure can transmit circularly polarized light in a specific band and reflect circularly polarized light in other bands. The circularly polarized light in the reflected band can be reflected by the reflective electrode in the light-emitting device and then pass through the spiral structure and the first composite film layer 81 in turn and then be emitted, thereby greatly improving the light extraction efficiency of the light-emitting device; in addition, when the light passes through multiple interfaces in the first composite film layer 81, refraction or scattering can occur, so that part of the light is emitted from the wide viewing angle direction (side viewing angle) of the light-emitting device, thereby taking into account the improvement of the wide viewing angle brightness of the light-emitting device.

[0148] In some methods for preparing brightness enhancement films provided in embodiments of the present application, the step of forming a second liquid crystal polymer layer on the substrate in step S82 includes:

[0149] S821 , using step-by-step polymerization to control the intensity of ultraviolet light irradiation to form multiple sub-layers in the second liquid crystal polymer layer 82 .

[0150] For example, taking the second liquid crystal polymer layer 82 including a first sublayer, a second sublayer, and a third sublayer arranged in sequence as an example, the preparation process of the third sublayer (for example, B-CLC) is described as follows:

[0151] S10, forming a uniform B-CLC prepolymer by mixing the non-liquid crystal monomer R10-X-R11, the nematic liquid crystal monomer and the photoinitiator according to the proportions described above;

[0152] S20, coating a B-CLC prepolymer on a substrate;

[0153] S30, forming a third sublayer (e.g., B-CLC) having a pitch gradient distribution by step-by-step UV polymerization;

[0154] Specifically, the step S30 includes the following two sub-steps:

[0155] Sub-step 1: UV irradiation intensity 0.2mW / cm 2 , under the condition of temperature 25℃, polymerization for 5min;

[0156] Sub-step 2: UV irradiation intensity 10mW / cm 2 , polymerization was carried out at a temperature of 25°C for 5 minutes.

[0157] The second sublayer and the first sublayer are sequentially formed on the third sublayer. The second sublayer and the first sublayer can be prepared by the same method as the third sublayer, which will not be described again here.

[0158] In order to illustrate the application effect of the brightness enhancement film provided in the embodiments of the present application in a light-emitting device, a description of the specific components, preparation methods and experimental data of a group of brightness enhancement films is provided below.

[0159] The control group is a light-emitting device in the related art; the light-emitting devices in experimental groups 1 and 2 include a second liquid crystal polymer layer 82 formed by B-CLC, G-CLC and R-CLC polymer films, and the first composite film layer 81 is not provided; the light-emitting devices in experimental groups 3 to 7 are all provided with the brightness enhancement film provided in the embodiments of the present application.

[0160] The brightness data is obtained by testing at a straight viewing angle (0°), while the brightness decay (L-decay) data is obtained by testing at a side viewing angle (30°).

[0161] From the data in Table 1, it can be seen that compared with the control group, the brightness data of the red sub-pixel (R-pixel), green sub-pixel (G-pixel) and blue sub-pixel (B-pixel) in experimental group 1 and experimental group 2 are significantly improved, and the power consumption is also reduced, but the brightness decay L-decay is increased (that is, the side viewing angle brightness decay is aggravated). Compared with the control group, the brightness data of the red sub-pixel (R-pixel), green sub-pixel (G-pixel) and blue sub-pixel (B-pixel) in experimental group 3 to experimental group 7 are significantly improved, the power consumption is also reduced, and the increase in brightness decay L-decay is not obvious (that is, the side viewing angle brightness decay is much improved compared with experimental group 1 and experimental group 2). In particular, there is almost no brightness decay L-decay in experimental group 3, experimental group 4 and experimental group 7, and the brightness decay L-decay is equivalent to that of the control group. This shows that the brightness enhancement film provided by the embodiments of the present application can improve the brightness of the light-emitting device while taking into account the brightness of a large viewing angle, thereby improving the display effect.

[0162] Table 1: Comparison of photoelectric function test results of the light-emitting device in the related art and the light-emitting device of the present application

[0163]

[0164] The structural formulas of the chemical components involved in the second liquid crystal polymer layer 82 in the light-emitting devices of each experimental group are as follows:

[0165]

[0166] (called photoinitiator Irg651),

[0167] (called light absorber UV531).

[0168] Among them, I-1, I-2, and II-1 are all nematic liquid crystal monomers, and III-1, III-2, and III-3 are chiral additives.

[0169] In addition, the structural formulas of the chemical components involved in the first composite thin film layer 81 in the light-emitting devices of each experimental group are as follows:

[0170]

[0171]

[0172] (called photoinitiator Irg651);

[0173] Among them, I-1, I-2, and II-1 are all nematic liquid crystal monomers, and V-1 and V-2 are non-liquid crystal monomers.

[0174] The following briefly describes the differences in the structure and preparation methods of the light-emitting devices of the control group and each experimental group.

[0175] Control group:

[0176] The light-emitting device comprises a substrate, an anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode, a thin film encapsulation layer and a polarizer which are sequentially arranged on the substrate.

[0177] Experimental Group 1:

[0178] The light-emitting device includes a substrate, an anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode, and a thin film encapsulation layer arranged in sequence on the substrate; a B-CLC prepolymer is coated on the thin film encapsulation layer, and a single-step UV polymerization is used to form a uniform pitch cholesteric liquid crystal polymer film, and the UV irradiation intensity is 10mW / cm 2 The polymerization time was 7 minutes, and the polymerization temperature was 25°C. An adhesive layer (OCA) was then applied or left untreated. Following the same preparation process, G-CLC and R-CLC polymer films were sequentially polymerized, followed by attachment of a polarizer. In other words, Experimental Group 1 included only the second liquid crystal polymer layer 82 formed from the B-CLC, G-CLC, and R-CLC polymer films; the first composite film layer 81 was omitted.

[0179] The mass fraction ratios of the components of the B-CLC prepolymer and the mass fraction ratios of the components are as follows: I-1 / I-2 / II-1 / III-1 / III-3 / IV-1: 15 / 15 / 50 / 10 / 5 / 5.

[0180] The mass fraction ratios of the components of the G-CLC prepolymer and among the components are as follows: I-1 / I-2 / II-1 / III-1 / III-2 / IV-1:15 / 15 / 50 / 5 / 10 / 5.

[0181] The mass fraction ratios of the components of the R-CLC prepolymer and among the components are as follows: I-1 / I-2 / II-1 / III-1 / III-2 / IV-1:15 / 15 / 50 / 10 / 5 / 5.

[0182] Experimental Group 2:

[0183] The light-emitting device includes a substrate, an anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode, and a thin film encapsulation layer arranged in sequence on the substrate; a B-CLC prepolymer is coated on the thin film encapsulation layer, and a cholesteric liquid crystal polymer film with a gradient pitch is formed by step-by-step UV polymerization. The first step of UV irradiation intensity is 0.2 mW / cm 2 , polymerization time 5min, polymerization temperature 25℃, second step UV irradiation intensity 10mW / cm 2 The polymerization time was 5 minutes and the polymerization temperature was 25°C. An adhesive layer (OCA) was then applied or left untreated. Following the same preparation process, G-CLC and R-CLC polymer films were sequentially polymerized, followed by attachment of a polarizer. In other words, Experimental Group 2 included only the second liquid crystal polymer layer 82 formed from the B-CLC, G-CLC, and R-CLC polymer films; the first composite film layer 81 was omitted.

[0184] The mass fraction ratios of the components of the B-CLC prepolymer and the mass fraction ratios of the components are as follows: I-1 / I-2 / II-1 / III-1 / III-3 / IV-1 / IV-2: 15 / 15 / 50 / 10 / 5 / 4 / 1.

[0185] The mass fraction ratios of the components of the G-CLC prepolymer and among the components are as follows: I-1 / I-2 / II-1 / III-1 / III-2 / IV-1 / IV-2: 15 / 15 / 50 / 5 / 10 / 4 / 1.

[0186] The mass fraction ratios of the components of the R-CLC prepolymer and among the components are as follows: I-1 / I-2 / II-1 / III-1 / III-2 / IV-1 / IV-2: 15 / 15 / 50 / 10 / 5 / 4 / 1.

[0187] Experimental Group 3:

[0188] Based on Experimental Group 2, a first composite film layer 81 was formed on the second liquid crystal polymer layer 82. Specifically, a prepolymer consisting of a mixture of non-liquid crystal monomers R10-X-R11, nematic liquid crystal monomers, and a photoinitiator was coated on the second liquid crystal polymer layer 82. The first composite film layer 81 was prepared by step-by-step polymerization. The first step of ultraviolet irradiation had an intensity of 0.1 mW / cm 2 , polymerization time 1min, polymerization temperature 25℃, second step UV irradiation intensity 10mW / cm 2 , polymerization time 5min, polymerization temperature 25℃, the thickness of the prepared micro-scattering layer is 10μm, and then the polarizer is attached.

[0189] The mass fraction ratio of each component in the prepolymer of the second liquid crystal polymer layer 82 is as follows: I-1 / I-2 / II-1 / V-1 / V-2 / IV-1: 15 / 15 / 50 / 4 / 16 / 2.

[0190] Experimental Group 4:

[0191] Based on Experimental Group 2, a first composite film layer 81 was formed on the second liquid crystal polymer layer 82. Specifically, a prepolymer consisting of a mixture of non-liquid crystal monomers R10-X-R11, nematic liquid crystal monomers, and a photoinitiator was coated on the second liquid crystal polymer layer 82. The first composite film layer 81 was prepared by step-by-step polymerization. The first step of ultraviolet irradiation had an intensity of 0.1 mW / cm 2 , polymerization time 1min, polymerization temperature 25℃, second step UV irradiation intensity 10mW / cm 2 , polymerization time 5min, polymerization temperature 25℃, the thickness of the prepared micro-scattering layer is 10μm, and then the polarizer is attached.

[0192] The mass fraction ratio of each component in the prepolymer of the second liquid crystal polymer layer 82 is as follows: I-1 / I-2 / II-1 / V-1 / V-2 / IV-1: 13 / 12 / 45 / 6 / 24 / 2.

[0193] Experimental Group 5:

[0194] Based on Experimental Group 2, a first composite film layer 81 was formed on the second liquid crystal polymer layer 82. Specifically, a prepolymer consisting of a mixture of non-liquid crystal monomers R10-X-R11, nematic liquid crystal monomers, and a photoinitiator was coated on the second liquid crystal polymer layer 82. The first composite film layer 81 was prepared by step-by-step polymerization. The first step of ultraviolet irradiation had an intensity of 0.1 mW / cm 2 , polymerization time 1min, polymerization temperature 25℃, second step UV irradiation intensity 10mW / cm 2 , polymerization time 5min, polymerization temperature 25℃, the thickness of the prepared micro-scattering layer is 10μm, and then the polarizer is attached.

[0195] The mass fraction ratio of each component in the prepolymer of the second liquid crystal polymer layer 82 is as follows: I-1 / I-2 / II-1 / V-1 / V-2 / IV-1: 17 / 17 / 56 / 2 / 8 / 2.

[0196] Experimental Group 6:

[0197] Based on Experimental Group 2, a first composite film layer 81 was formed on the second liquid crystal polymer layer 82. Specifically, a prepolymer consisting of a mixture of non-liquid crystal monomers R10-X-R11, nematic liquid crystal monomers, and a photoinitiator was coated on the second liquid crystal polymer layer 82. The first composite film layer 81 was prepared by step-by-step polymerization. The first step of ultraviolet irradiation had an intensity of 0.1 mW / cm 2 , polymerization time 1min, polymerization temperature 25℃, second step UV irradiation intensity 10mW / cm 2 , polymerization time 5min, polymerization temperature 25℃, the thickness of the prepared micro-scattering layer is 5μm, and then the polarizer is attached.

[0198] The mass fraction ratio of each component in the prepolymer of the second liquid crystal polymer layer 82 is as follows: I-1 / I-2 / II-1 / V-1 / V-2 / IV-1: 15 / 15 / 50 / 4 / 16 / 2.

[0199] Experimental Group 7:

[0200] Based on Experimental Group 2, a first composite film layer 81 was formed on the second liquid crystal polymer layer 82. Specifically, a prepolymer consisting of a mixture of non-liquid crystal monomers R10-X-R11, nematic liquid crystal monomers, and a photoinitiator was coated on the second liquid crystal polymer layer 82. The first composite film layer 81 was prepared by step-by-step polymerization. The first step of ultraviolet irradiation had an intensity of 0.1 mW / cm 2 , polymerization time 1min, polymerization temperature 25℃, second step UV irradiation intensity 10mW / cm 2 , polymerization time 5min, polymerization temperature 25℃, the thickness of the prepared micro-scattering layer is 20μm, and then the polarizer is attached.

[0201] The mass fraction ratio of each component in the prepolymer of the second liquid crystal polymer layer 82 is as follows: I-1 / I-2 / II-1 / V-1 / V-2 / IV-1: 15 / 15 / 50 / 4 / 16 / 2.

[0202] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A brightness enhancement film, characterized in that: include: a first composite film layer, the first composite film layer comprising a microporous structure and a first liquid crystal polymer disposed in the microporous structure; and a second liquid crystal polymer layer located on one side of the first composite film layer; the second liquid crystal polymer layer includes at least one sublayer, and the sublayer has a plurality of helical structures.

2. The brightness enhancement film according to claim 1, characterized in that Along the direction from the second liquid crystal polymer layer to the first composite film layer, the pitches of the multiple helical structures change gradually.

3. The brightness enhancement film according to claim 2, characterized in that: Along the direction from the second liquid crystal polymer layer to the first composite film layer, the pitches of the plurality of helical structures in the same sub-layer gradually increase.

4. The brightness enhancement film according to claim 3, characterized in that: The half pitch of the multiple helical structures ranges from 125 nm to 220 nm.

5. The brightness enhancement film according to claim 4, characterized in that: The second liquid crystal polymer layer includes one sub-layer, and the thickness of the second liquid crystal polymer layer is in the range of 0.5 μm to 50 μm.

6. The brightness enhancement film according to claim 4, characterized in that: The second liquid crystal polymer layer includes a first sublayer, a second sublayer and a third sublayer arranged in sequence, and the first sublayer is in contact with the first composite film layer; The half pitch of the multiple helical structures in the first sublayer ranges from 125 nm to 165 nm, the half pitch of the multiple helical structures in the second sublayer ranges from 155 nm to 195 nm, and the half pitch of the multiple helical structures in the third sublayer ranges from 185 nm to 220 nm. The thickness of the first sublayer, the second sublayer and the third sublayer are all in the range of 0.5 μm to 5 μm.

7. The brightness enhancement film according to claim 6, characterized in that: An adhesive layer is provided between the first sub-layer and the second sub-layer, and between the second sub-layer and the third sub-layer.

8. A light emitting device, characterized in that: The brightness enhancement film according to any one of claims 1 to 7, further comprising: substrate; A first electrode, a light-emitting layer, a second electrode, an encapsulation layer, the brightness enhancement film and a polarizer are sequentially arranged on the substrate; The second liquid crystal polymer layer in the brightness enhancement film is located on a side of the first composite film layer in the brightness enhancement film away from the polarizer.

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