Light emitting element and light emitting device

Abstract

A light emitting element comprising a first LED light source (11) for emitting blue light (aa), a second LED light source (12) for emitting red light (bb) and a light emitting layer (100), the light emitting layer (100) comprising a solid polymer composition and green light emitting crystals (1). The solid polymer composition comprises a polymer (2). The green light emitting crystals (1) are perovskite crystals. The first light source (11) and the second light source (12) are directed towards the light emitting layer (100). Upon absorption of light emitted by the first light source (11), the light emitting crystals (20) emit light at wavelengths in the green light spectrum (cc).

Description

Technical Field

[0001] The present invention relates in a first aspect to a light-emitting element, and in a second aspect to a light-emitting device including the light-emitting element. Background Technology

[0002] Existing liquid crystal displays (LCDs) or display elements include quantum dot-based elements. Specifically, the backlight element of such an LCD may include RGB backlighting composed of red, blue, and green light. Currently, quantum dot particles are typically used to generate the backlight colors of such backlight elements.

[0003] Manufacturing such components presents various challenges. One challenge is embedding nanocrystals into the components. Due to the different chemical properties of quantum dots, incompatibility may exist between various embedding materials containing quantum dots, or even between quantum dots embedded in the same material. This incompatibility can lead to the degradation of materials in the display components, and thus may affect the lifespan of such displays.

[0004] US 2017 / 186922 A1 discloses an electronic device comprising: a light source having peak emission at wavelengths of about 440 nm to about 480 nm; and a light conversion layer disposed on the light source. The light conversion layer comprises a first quantum dot emitting red light and a second quantum dot emitting green light. At least one of the first and second quantum dots has a perovskite crystal structure and comprises a compound represented by chemical formula 1: AB'X 3+α Where A is a group IA metal, NR4 + B′ or a combination thereof, where B′ is a Group IVA metal, X is a halogen, BF4 - , or combinations thereof, and α is between 0 and 3.

[0005] Document WO 2017 / 195062 A1 discloses devices and systems comprising halide-containing perovskites and / or phosphors for generating visible light and / or communicating using visible light, etc.

[0006] Document WO 2018 / 146561 A1 discloses compositions and methods related to light-converting luminescent composite materials.

[0007] Document WO 2017 / 108568 A1 discloses a light-emitting element comprising: a first film containing a first solid polymer composition and a second film containing a second solid polymer composition. The first solid polymer composition contains a first light-emitting crystal. The second solid polymer composition contains a second light-emitting crystal. The first light-emitting crystal has a size between 3 nm and 3000 nm and emits red light in response to excitation by shorter wavelength light. The second light-emitting crystal has a size between 3 nm and 3000 nm and emits green light in response to excitation by shorter wavelength light.

[0008] Document WO 2020 / 130592 A1 relates to a metal halide perovskite light-emitting device and its manufacturing method. According to this invention, the metal halide perovskite light-emitting device uses a perovskite film with a multidimensional crystal structure derived from a proton transfer reaction as the light-emitting layer. This allows for the suppression of ion transfer and the removal of surface defects through a self-assembled shell, thereby improving photoluminescence intensity, luminous efficiency, and lifetime. Furthermore, by injecting fluorine-based and alkaline materials into a PEDOT:PSS conductive polymer already used as a hole injection layer to adjust its acidity and improve the work function of the interface, and by using a chemically stable graphene barrier layer to protect the acid-sensitive electrodes, a high-efficiency light-emitting device can be fabricated. Summary of the Invention

[0009] Therefore, the problem to be solved by the present invention is to provide a light-emitting element manufactured in a manner that prevents incompatibility of quantum dot materials in light-emitting elements (especially LCD displays).

[0010] The present invention will now be described in detail. It should be understood that the various embodiments, preferences, and scopes provided / disclosed in this specification can be combined arbitrarily. Furthermore, depending on the specific embodiment, the selected definition, embodiment, or scope may not apply.

[0011] Unless otherwise stated, the following definitions shall apply to this specification:

[0012] The terms “a,” “an,” “the,” and similar terms as used in the context of this invention are to be interpreted to cover both the singular and plural unless otherwise stated herein or obviously contradicted by the context. The term “comprising” shall include all of the following: “comprising,” “consistently comprising,” and “composed of.” Percentages are given in weight % unless otherwise stated herein or obviously contradicted by the context. “Independently” means that a substituent / ion may be selected from one of the specified substituents / ions or may be a combination of more than one of the foregoing items.

[0013] The term "luminescent crystal" (LC) is known in the art and refers to crystals of 2-100 nm made of semiconductor materials. This term includes nanocrystals, typically in the 2-100 nm range, and quantum dots, typically in the 2-10 nm range. Preferably, the luminescent crystal is approximately isometric (e.g., spherical or cubic). A particle is considered approximately isometric if the aspect ratio (longest direction: shortest direction) of all three orthogonal dimensions is 1-2. Therefore, components of an LC preferably contain 50-100% (n / n), preferably 66-100% (n / n), and more preferably 75-100% (n / n) of isometric nanocrystals.

[0014] As the terminology suggests, LC indicates luminescence. In the context of this invention, the term luminescent crystal includes both single-crystal and polycrystalline particles. In the latter case, a particle may consist of several crystal domains (grains) connected by crystalline or amorphous phase boundaries. A luminescent crystal is a semiconductor material exhibiting a direct bandgap (typically in the range of 1.1–3.8 eV, more typically 1.4–3.5 eV, and even more typically 1.7–3.2 eV). When irradiated with electromagnetic radiation equal to or greater than this bandgap, valence band electrons are excited to the conduction band, leaving electron-hole pairs in the valence band. The formed excitons (electron-electron-hole pairs) then radiatively recombine in the form of photoluminescence, with the maximum intensity centered near the LC bandgap value, exhibiting a photoluminescence quantum yield of at least 1%. LC can also exhibit electroluminescence upon contact with external electron and electron-hole sources.

[0015] The term "quantum dot" (QD) is known, and it specifically refers to semiconductor nanocrystals with diameters typically between 2 and 10 nm. Within this range, the physical radius of a QD is smaller than the bulk excited Bohr radius, leading to a dominance of quantum confinement effects. Therefore, the electronic states and band gap of a QD are functions of its composition and physical size; that is, the color of absorption / emission is related to the QD size. The optical quality of a QD sample is directly related to its uniformity (QDs with higher monodispersity will have smaller emission volumes with lower free wave sizes). When a QD reaches a size larger than the Bohr radius, the quantum confinement effect is hindered, and the sample may no longer emit light because the nonradiative pathway of exciton recombination may dominate. Therefore, QDs are a specific subgroup of nanocrystals, specifically determined by their size.

[0016] The term "perovskite crystal" is known, and specifically includes crystalline compounds with a perovskite structure. Such perovskite structures are known in themselves and are described as cubic, pseudocubic, tetragonal, or orthorhombic crystals of the general formula M1M2X3, where M1 is a cation with a coordination number of 12 (cuboctaeder), M2 is a cation with a coordination number of 6 (octaeder), and X is an anion in a cubic, pseudocubic, tetragonal, or orthorhombic position in the crystal lattice. In these structures, the selected cation or anion can be substituted by other ions (randomly or often up to 30 atomic percent), resulting in doped or non-stoichiometric perovskites that retain their original crystal structure. The manufacture of such luminescent crystals is known, for example, from WO2018 028869.

[0017] The term "polymer" is known and includes organic and inorganic synthetic materials containing repeating units ("monomers"). The term polymer includes homopolymers and copolymers. It also includes crosslinked and non-crosslinked polymers. Depending on the context, the term polymer should include both its monomers and oligomers. For example, polymers include: acrylate polymers, carbonate polymers, sulfone polymers, epoxy polymers, vinyl polymers, urethane polymers, imide polymers, ester polymers, furan polymers, melamine polymers, styrene polymers, norbornene polymers, silicone polymers, silazane polymers, and cycloolefin copolymers. Polymers may include other materials conventional in the art, such as polymerization initiators, stabilizers, fillers, and solvents.

[0018] Polymers can be further characterized by physical parameters, such as polarity, glass transition temperature (Tg), Young's modulus, and light transmittance.

[0019] Transmittance: Typically, the polymers used in the context of this invention are light-transmitting (i.e., transparent) to allow light emitted by the light-emitting crystal and possible light from the light source used to excite the light-emitting crystal to pass through. Transmittance can be determined by white light interferometry or ultraviolet-visible spectroscopy.

[0020] Glass transition temperature (Tg) is a recognized parameter in the field of polymers; it describes the temperature at which an amorphous or semi-crystalline polymer transitions from a glassy (hard) state to a softer, more pliable, or rubbery state. Polymers with high Tg are considered "hard," while those with low Tg are considered "soft." At the molecular level, Tg is not a discrete thermodynamic transition, but rather the temperature range in which the mobility of polymer chains increases significantly. However, it is customary to report a single temperature, defined as the midpoint of the temperature range, bounded by the tangents to the two flat regions of the heat flow curve measured by DSC. Tg can be determined using DSC according to DIN EN ISO 11357-2 or ASTM E 1356. This method is particularly suitable if the polymer exists in the form of a loose material. Alternatively, Tg can be determined by measuring temperature-dependent micron or nanohardness using microindentation or nanoindentation according to ISO 14577-1 or ASTM E 2546-15. This method is applicable to the light-emitting elements and lighting devices disclosed herein. Suitable analytical equipment includes MHT (Anton Paar), Hysitron TI Premier (Bruker), or NanoIndenter G200 (Keysight Technologies). Data obtained through temperature-controlled microindentation and nanoindentation can be converted to Tg. Typically, the change in plastic deformation work, Young's modulus, or hardness with temperature is measured, and Tg is the temperature at which these parameters change significantly.

[0021] Young's modulus, or the modulus of elasticity, is a mechanical property that measures the stiffness of a solid material. It defines the relationship between stress (force per unit area) and strain (proportional deformation) in a material within the linear elastic range of uniaxial deformation.

[0022] According to the present invention, the above-mentioned problems are solved by a first aspect of the invention. A light-emitting element includes: a first light source for emitting blue light, a second light source for emitting red light, and a light-emitting layer. The light-emitting layer includes a solid polymer composition and a green light-emitting crystal. The solid polymer composition comprises a polymer. The green light-emitting crystal is a perovskite crystal selected from compounds of formula (I).

[0023] [M 1 A 1 ] a M 2 b X c (I), where:

[0024] A 1 It represents one or more organic cations, particularly formamidinium (FA).

[0025] M 1It represents one or more alkali metals, especially Cs.

[0026] M 2 Indicates one or more except M 1 Other metals, especially Pb,

[0027] X represents one or more anions selected from halide ions, pseudohalides, and sulfides, especially Br.

[0028] a represents 1-4,

[0029] b represents 1-2,

[0030] c represents 3-9, and

[0031] Where there exists M 1 、or A 1 、 or M 1 and A 1 .

[0032] Blue light emitted by the first light source and red light emitted by the second light source pass through the light-emitting layer. When absorbing the blue light emitted by the first light source, the light-emitting crystal emits light of wavelengths in the green light spectrum.

[0033] In particular, the second layer of light-emitting crystals emits light with a wavelength longer than that of the first light source.

[0034] In particular, Equation (I) describes a perovskite luminescent crystal that, when absorbing blue light, emits light with wavelengths between 500 nm and 550 nm in the green light spectrum, especially centered at about 527 nm.

[0035] In another advantageous embodiment of the invention, the green luminescent crystal is a perovskite crystal of formula (I'):

[0036] FAPbBr3 (I').

[0037] In another advantageous embodiment of the invention, M in the light-emitting layer (100) 2 The concentration is 100-1000 ppm, preferably 300-1000 ppm, and very preferably 500-1000 ppm.

[0038] In another advantageous embodiment of the invention, the M of the light-emitting layer (100) 2 Loading amount is 5-200 mg / m³ 2 Favorable concentration is 10-100 mg / m³ 2 Very favorable at 20-80 mg / m² 2 .

[0039] In addition, the haze h1 of the luminescent layer is 10%.

[0040] In another advantageous embodiment of the invention, the haze h1 of the luminescent layer is h1 > 10%, particularly h1 > 20%, particularly h1 > 30%, and h1 < 80%, particularly h1 < 70%, very particularly h1 < 60%.

[0041] In another advantageous embodiment of the invention, the haze h1 of the luminescent layer is 20% ≤ h1 ≤ 80%, preferably 20% ≤ h1 ≤ 70%, and most preferably 30% ≤ h1 ≤ 60%.

[0042] In the context of this invention, haze refers to transmitted haze. Transmitted haze is the amount of light that is scattered at a wide angle, which means that when passing through a transparent material (the light-emitting layer in this invention), the angle from the normal incident direction is greater than 2.5° (measured by ASTM D1003; for example, using a Byk Gardner haze meter).

[0043] The low haze of the luminescent layer has the following technical advantages: the luminescent perovskite crystals in the luminescent layer are more stable, especially when exposed to blue light. This stability is a result of reduced multiple scattering of blue light in the luminescent layer due to the lower haze.

[0044] In addition, another technical effect of low haze is that lower haze results in higher display brightness, measured by the "light conversion factor" (LCF) of the second layer. The LCF of the emissive layer refers to the ratio between the intensity of green light emitted from the emissive layer in the vertical direction and the intensity of blue light that is extinct by the emissive layer in the vertical direction (e.g., through absorption, reflection, or scattering).

[0045] In another advantageous embodiment of the invention, the light-emitting layer is disposed away from the first and / or second light source. "Away" as used herein specifically means that the light-emitting layer is disposed such that it does not contact or substantially does not contact the first and / or second light source. "Away" can also mean that the light-emitting layer is disposed parallel to the first and / or second light source, and that there is a certain distance between the light-emitting layer and the first and / or second light source.

[0046] "Distance" can also refer to the arrangement where there is an air gap between the light-emitting layer and the first and / or second light source. This gap can be a vacuum gap or a gap filled with other gases. There may still be contact points or supporting structures between the first and / or second light source and the light-emitting layer.

[0047] In an advantageous embodiment of the invention, the first and second light sources are arranged adjacent to each other and at the same distance from the light-emitting layer. Therefore, the emitted light from the first and second light sources impacts the light-emitting layer with the same or similar intensity and / or at the same angle.​

[0048] Specifically, first and second light sources are positioned such that they are both located on the back side of the light-emitting layer, wherein light emitted from the first and / or second light sources impacts the light-emitting layer. Blue light from the first light source is partially absorbed by the light-emitting crystals of the light-emitting layer and partially passes through the light-emitting layer. Red light emitted from the second light source passes through the light-emitting layer substantially without being absorbed by the light-emitting crystals. Therefore, blue, red, and green light are emitted from the front side of the light-emitting layer.

[0049] As previously described, the light-emitting layer comprises a solid polymer composition and a green light-emitting crystal. Advantageously, the light-emitting crystal is embedded in the solid polymer composition.

[0050] 1. In an advantageous embodiment, the solid polymer composition comprises a polymer, wherein the polymer (2) is characterized by a molar ratio z of the sum of (oxygen + nitrogen) to carbon, wherein z ≤ 0.9, z ≤ 0.75, particularly z ≤ 0.4, particularly z ≤ 0.3, particularly z ≤ 0.25.

[0051] In another advantageous embodiment of the invention, the polymer comprises an acrylate. Advantageously, the polymer comprises or consists of repeating units selected from or composed of cyclic aliphatic acrylates.

[0052] In another advantageous embodiment, the polymer is crosslinked and comprises a polyfunctional acrylate.

[0053] In another advantageous embodiment, the glass transition temperature T of the solid polymer composition is... g For T g ≤120℃ (favorable T) g ≤100℃, very advantageous T g ≤80℃, most preferably T g ≤70℃). Each T g All measurements were taken during the second heating cycle according to DIN ENISO 11357-2:2014-07, with a heating rate of 20 K / min applied from -90 °C up to 250 °C. The purge gas was nitrogen (5.0 mL / min) at a rate of 20 mL / min. A DSC system, DSC 204 F1 Phoenix (Netzsch), was used. T was measured during the second heating cycle. g (The first heating from -90°C to 250°C showed superposition effects in addition to the glass transition).

[0054] In another advantageous embodiment of the invention, the solid polymer composition comprises scattering particles selected from metal oxide particles and polymer particles, preferably selected from TiO2, ZrO2, Al2O3 and organopolysiloxanes.

[0055] In another advantageous embodiment, the solid polymer composition is configured as a sheet polymer. The sheet polymer can have the shape of a polymer film with a film thickness typically 0.001-10 mm, most typically 0.01-0.5 mm. The sheet polymer can be continuous and flat, or discontinuous, having, for example, microstructures (e.g., prismatic shapes).

[0056] In another advantageous embodiment of the invention, the light-emitting layer forms a self-supporting film or a portion thereof.

[0057] In another advantageous embodiment of the invention, the light-emitting layer is sandwiched between two barrier layers to form a sandwich structure. Advantageously, the sandwich structure itself forms a self-supporting film or a portion thereof.

[0058] Specifically, this sandwich configuration refers to a configuration having a barrier layer, a light-emitting layer, and another barrier layer in the horizontal direction. The two barrier layers of the sandwich structure can be made of the same barrier layer material or different barrier layer materials.

[0059] The technical effect of the barrier layer is to improve the stability of the light-emitting crystals contained in the light-emitting layer, especially their stability against oxygen or moisture.

[0060] In particular, such barrier layers are known in the art; they typically comprise materials / combinations of materials with low water vapor transmission rate (WVTR) and / or low oxygen transmission rate (OTR). By selecting such materials, degradation of the light-emitting crystal in the element due to exposure to water vapor and / or oxygen is reduced or even avoided. At 40°C / 90% relative humidity and atmospheric pressure, the WVTR of the barrier layer or membrane is preferably less than 10 (g) / (m³). 2 *day), more preferably less than 1(g) / (m 2 *day), and the optimal value is less than 0.1(g) / (m 2 *sky).

[0061] In one embodiment, the barrier membrane may be oxygen-permeable. In an alternative embodiment, the barrier membrane is oxygen-impermeable and has an OTR (oxygen permeability) of <10 (mL) / (m²) at 23°C / 90% relative humidity and atmospheric pressure. 2 *day), more preferably <1(mL) / (m 2 *day), the optimal value is <0.1(mL) / (m 2 *sky).

[0062] In one embodiment, the barrier film is light-transmitting, i.e., its transmittance to visible light is >80%, preferably >85%, and most preferably >90%.

[0063] Suitable barrier films can exist in a single-layer form. Such barrier films are known in the art and comprise glass, ceramics, metal oxides, and polymers. Suitable polymers for the barrier film can be selected from polyvinylidene chloride (PVdC), cyclic olefin copolymers (COC), ethylene-vinyl alcohol copolymers (EVOH), high-density polyethylene (HDPE), and polypropylene (PP); suitable inorganic materials can be selected from metal oxides, SiOx, SixNy, and AlOx. Most preferably, the polymeric moisture-proof material comprises materials selected from PVdC and COC.

[0064] Most advantageously, the polymeric oxygen barrier material comprises a material selected from EVOH polymers.

[0065] Suitable barrier films can exist in a multilayer form. Such barrier films are known in the art and typically comprise a substrate, such as PET, with a thickness in the range of 10-200 μm, and a thin inorganic layer containing a material selected from SiOx and AlOx, or an organic layer based on liquid crystals embedded in a polymer matrix, or an organic layer containing a polymer with the desired barrier properties. Possible polymers for such organic layers include, for example, PVdC, COC, and EVOH.

[0066] In one implementation, the blue light emitting source and the red light emitting source are LEDs.

[0067] In another implementation, the blue light emitting source and the red light emitting source are separate light-emitting diodes (LEDs).

[0068] In another embodiment, the blue light emitting source and the red light emitting source are electroluminescent sources, such as light-emitting diodes (LEDs).

[0069] In another embodiment, the blue light emitting source is an LED chip containing gallium nitride, while the red light emitting source is an LED chip containing gallium indium phosphide.

[0070] A second aspect of the invention relates to a light-emitting device, particularly a liquid crystal display (LCD), which includes a light-emitting element according to the first aspect.

[0071] An advantageous embodiment of the light-emitting device includes a light-emitting layer and an array of light sources. The array of light sources includes more than one first light source and more than one second light source. Advantageously, the array of light sources includes pairs of first and second light sources. Therefore, the term "pair" refers to the arrangement of first and second light sources that are repeatedly arranged in the array.

[0072] In particular, the array of light sources and / or the light-emitting layer extends substantially over the entire area of ​​the liquid crystal display.

[0073] The pair of first and second light sources are specifically positioned on the back side of the light-emitting layer, such that the pair of first and second light sources emit light toward the light-emitting layer.

[0074] In another advantageous embodiment of the invention, the light-emitting device includes a diffuser plate or diffuser film disposed between the array of light sources and the light-emitting layer.

[0075] In another advantageous embodiment of the invention, a light guide plate and a diffuser film are disposed between the light source array and the light-emitting layer. Advantageously, the light emitted from the light source enters the light guide plate at a 90° angle relative to the light emitted by the light guide plate, which is then directed to the diffuser film and ultimately excites the light-emitting crystals in the light-emitting layer.

[0076] Advantageously, light emitted from the light source enters the diffuser or film at an angle of 0°, relative to light emitted from the light guide plate onto the diffuser and ultimately excites the light-emitting crystals in the light-emitting layer.

[0077] In another advantageous embodiment of the invention, one or more light sources in the array are each adapted to switch between on and off at a frequency f, wherein f ≥ 150 Hz, preferably f ≥ 300 Hz, and very preferably f ≥ 600 Hz.

[0078] Other advantageous embodiments are set forth in the dependent claims and the description below. Attached Figure Description

[0079] The invention will be better understood from the following detailed description, and other objects besides those described above will become apparent. This description refers to the accompanying drawings, in which:

[0080] Figure 1 a shows the emission spectra of the first and second light sources;

[0081] Figure 1 b shows the corresponding Figure 1 A schematic diagram of the first and second light sources for the emission spectrum of a;

[0082] Figure 2 a shows the emission spectrum of an embodiment of the light-emitting element;

[0083] Figure 2 b shows the corresponding Figure 2 A schematic diagram of the light-emitting element with emission spectrum of b;

[0084] Figure 3 A schematic diagram of another embodiment of the light-emitting element is shown; and

[0085] Figure 4 A schematic diagram of an embodiment of the light-emitting device is shown. Detailed Implementation Plan

[0086] The embodiments, examples, and experiments that represent or lead to the embodiments, aspects, and advantages of the invention will be better understood from the following detailed description of the invention. This description refers to the accompanying drawings, in which:

[0087] Figure 1 a shows the emission spectra of a first light source 11 for emitting blue light aa and a second light source 12 for emitting red light bb.

[0088] As expected, the emission spectrum shows that the peak of blue light (aa) is at about 440 nm, and the peak of red light (bb) is at about 630 nm.

[0089] Figure 1 b shows a schematic diagram of a first light source 11 for emitting blue light aa and a second light source 12 for emitting red light bb.

[0090] Figure 2 a shows the emission spectrum of a light-emitting element according to a first embodiment of the present invention.

[0091] Figure 2 b shows a schematic diagram of a light-emitting element according to an embodiment of the present invention. The light-emitting element includes a first light source 11 for emitting blue light aa and a second light source 12 for emitting red light bb. Furthermore, the light-emitting element includes a light-emitting layer 100, which comprises a solid polymer composition and a green light-emitting crystal 1. The solid polymer composition comprises a polymer 2. The green light-emitting crystal is a perovskite crystal selected from compounds of formula (I).

[0092] Light emitted by the first light source 11 and the second light source 12 passes through the light-emitting layer. Upon absorbing light emitted by the first light source 11, the light-emitting crystal 20 emits light with a wavelength in the green light spectrum cc. The haze h1 of the light-emitting layer 100 is 10% < h1 < 100%.

[0093] Advantageously, the green luminescent crystal 1 is a perovskite crystal of formula (I').

[0094] More advantageously, M in the light-emitting layer 100 2 The concentration can be 100-1000 ppm, especially 300-1000 ppm, and very especially 500-1000 ppm.

[0095] More advantageously, the M of the light-emitting layer 100 2 The concentration can be 5-200 mg / m³ 2 Especially 10-100mg / m 2 Especially important is 20-80 mg / m². 2 .

[0096] More advantageously, the haze h1 of the luminescent layer 100 can be h1 < 80%, particularly h1 < 70%, and very particularly h1 < 60%.

[0097] In another advantageous embodiment of the invention, the haze h1 of the light-emitting layer is 20≤h1≤80%, preferably 20≤h1≤70%, and most preferably 30≤h1≤60%.

[0098] More advantageously, the light-emitting layer 100 can be positioned away from the first light source 11 and / or the second light source 12.

[0099] More advantageously, the solid polymer composition is characterized by a molar ratio z of the sum of (oxygen + nitrogen) to carbon, wherein z ≤ 0.9, z ≤ 0.75, particularly z ≤ 0.4, particularly z ≤ 0.3, particularly z ≤ 0.25.

[0100] More advantageously, the solid polymer composition may contain acrylates, and very particularly, polymer 2 contains cyclic aliphatic acrylates.

[0101] More advantageously, the glass transition temperature T of the solid polymer composition g For T g ≤120℃, especially T g ≤100℃, especially T g ≤80℃, especially T g ≤70℃.

[0102] In another advantageous embodiment of the invention, the solid polymer composition may comprise scattering particles selected from metal oxide particles and polymer particles, preferably selected from TiO2, ZrO2, Al2O3 and organopolysiloxanes.

[0103] In another advantageous embodiment, the light-emitting layer 100 may form a self-supporting film or a portion thereof.

[0104] Figure 3 Another embodiment of the light-emitting element is shown. Besides... Figure 2 Besides the component shown in b, Figure 3 The light-emitting element also includes a barrier layer 101, wherein the light-emitting layer 100 is sandwiched between the barrier layers 101. In particular, this sandwich structure can form a self-supporting layer or a part of a self-supporting layer.

[0105] Figure 4 A schematic diagram of an embodiment of the light-emitting device according to the second aspect of the present invention is shown. For example... Figure 2 b and Figure 3 The light-emitting element shown is integrated into the light-emitting device. The light-emitting device includes an array of light sources and a light-emitting layer 100. The array of light sources includes more than one first light source 11 and more than one second light source 12.

[0106] Advantageously, the array of light sources includes pairs of first light sources 11 and second light sources 12, which are arranged adjacent to each other, as Figure 4 shown in the embodiments of

[0107] Advantageously, the array of light sources and / or the light-emitting layer 100 extends substantially over the entire area of the liquid crystal display.

[0108] In another advantageous embodiment, the light-emitting device may include a diffuser plate or a diffuser film 101 disposed between the array of light sources and the light-emitting layer 100.

[0109] Experimental section

[0110] Example 1: A backlight unit for an LCD display was prepared by using the elements described herein. Figure 1 b shows a schematic diagram of the array element, and its emission spectrum was measured and shown in Figure 1 a. Figure 2 The element in b includes a first light source 11 for emitting blue light aa and a second light source 12 for emitting red light bb.

[0111] The emission spectrum of the element shows peaks in the visible blue and red ranges of the spectrum.

[0112] For measurement of data, a 2D array of 60 single blue GaN-based LEDs and 60 single red AlGaInP-based LEDs was used.

[0113] Example 2: Using the array of Example 1, additionally a diffuser plate was placed on top of the light source array. The diffuser plate is used to evenly distribute the light generated by the LEDs. A green remote perovskite QD film (self-supporting film) was placed on top (only loosely placed; no cementing or similar treatment). Then two cross prism films (cross BEF) and a brightness enhancement film (DBEF) were placed on top of the green perovskite film (not shown in the figure). The emission spectrum of the complete backlight structure was measured using a spectrometer (Konica Minolta CS-2000) showing blue, red, and green emission peaks, as Figure 2 shown in a.

[0114] Example 3: Preparation of a green remote perovskite QD film with low haze h1 and low T g as a self-supporting film:

[0115] Green light perovskite QDs with a composition of lead formamidinium tribromide (FAPbBr3) were synthesized in toluene as follows: Lead formamidinium tribromide (FAPbBr3) was synthesized by grinding PbBr2 and FABr. Specifically, 16 mmol PbBr2 (5.87 g, 98% ABCR, Karlsruhe (DE)) and 16 mmol FABr (2.00 g, Greatcell Solar Materials, Queanbeyan, (AU)) were ground together with yttrium-stabilized zirconia beads (5 mm diameter) for 6 hours to obtain pure cubic FAPbBr3, which was confirmed by XRD. Orange FAPbBr3 powder was added to oleylamine (80-90, Acros Organics, Geel (BE)) (weight ratio FAPbBr3:oleylamine = 100:15) and toluene (>99.5%, Puriss, Sigma Aldrich). The final concentration of FAPbBr3 was 1 wt%. The mixture was then dispersed for 1 hour by ball milling using yttrium-stabilized zirconia beads with a diameter of 200 μm under ambient conditions (unless otherwise defined, all experimental atmosphere conditions were: 35 °C, 1 atm, in air) to produce an ink with green luminescence.

[0116] Film Formation: 0.1 g of green ink was mixed with a UV-curable monomer / crosslinker mixture (0.7 g FA-513AS, Hitachi Chemical, Japan / 0.3 g Miramer M240, Miwon, Korea) containing 1 wt% photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TCI Europe, Netherlands) and 2 wt% polymer scattering particles (organopolysiloxane, ShinEtsu, KMP-590) in a rapid mixer, and toluene was evaporated under vacuum (<0.01 mbar) at room temperature. The resulting mixture contained 500 ppm Pb, as measured by inductively coupled optical emission spectrometry (ICP-OES). This mixture was then coated at a 50 μm thickness onto a 100 μm barrier film (supplier: I-components (Korea); product: TBF-1007), and then laminated with a second barrier film of the same type. The laminated structure was then UV-cured for 60 seconds (UVAcube100, equipped with a mercury lamp and quartz filter, Hohenler, Germany). When placed over a blue LED light source (450nm emission wavelength) and with two intersecting prisms (X-BEF) and a brightness enhancement film (DBEF) on top of the QD film, the initial properties of the resulting green perovskite QD film showed an emission wavelength of 526nm, an FWHM of 22nm, and a color coordinate (“y-value”, CIE1931) of y = 0.15 (optical properties measured using a Konica Minolta CS-2000). The resulting QD film had a haze of 50% and a transmittance of 85% (measured using a Byk Gardner haze meter). Light conversion factor (LCF; LCF = intensity of emitted green light (integrated emission peak) divided by the decrease in intensity of blue light (integrated emission peak); measured using a Konica Minolta CS-2000 from the vertical emission of green and blue light from the QD film).

[0117] According to DIN EN ISO 11357-2:2014-07, the glass transition temperature T of the UV-cured resin composition was determined by DSC. g The initial temperature was -90℃, and the final temperature was 250℃. The heating rate in a nitrogen atmosphere was 20 K / min (20 ml / min). The purge gas was nitrogen (5.0 g) at a flow rate of 20 ml / min. A DSC system, DSC 204F1 Phoenix (Netzsch), was used. T was measured during the second heating cycle. g (The initial heating from -90°C to 250°C revealed superimposed effects in addition to the glass transition). For DSC measurements, the UV-curable resin composition was removed from the QD film by peeling off the barrier film. Measurement of the UV-curable resin composition (T) g The temperature is 75℃.

[0118] By placing the QD film in a high blue light intensity light box (supplier: Hoenle; model: LED CUBE 100IC), the blue light flux on the QD film is 220 mW / cm² at a QD film temperature of 50°C. 2 The stability of the QD film was tested under blue LED light irradiation for 1000 hours. The changes in the optical parameters of the QD film after 1000 hours of flux testing were measured using the same procedures as for measuring the initial performance (as described above). The changes in the optical parameters are as follows:

[0119] • Change in y-value: from 0.15 to 0.119 (-0.031)

[0120] • Change in LCF: from 50% to 40% (-10%)

[0121] • Changes in green light emission wavelength: from 526nm to 525nm (-1nm)

[0122] • Changes in green FWHM: 0nm

[0123] Comparative Example 1 regarding Example 3: High haze and low T g Preparation of green light remote perovskite QD films.

[0124] The process is the same as the previous process for low-haze QD membranes, except for the following parameters:

[0125] • The total phosphorus content of the UV-curable acrylate mixture is 200 ppm.

[0126] • 12% by weight of scattering particles KMP-590 were mixed into a UV-curable acrylate mixture to increase the haze of the final QD film.

[0127] The resulting green perovskite QD film exhibited an emission wavelength of 525 nm, an FWHM of 22 nm, and a y-value of 0.149 (almost identical to the low-haze QD film in Experiment 3). The LCF of the QD film was 43%. The haze of the QD film was 98%, and the transmittance was 81%. Measurements of the UV-cured resin composition (T) g The temperature was 77℃. It can be seen that the LCF was lower than in Experiment 3. Higher haze leads to a lower LCF, and lower haze leads to a higher LCF. Therefore, lower haze in the QD film is beneficial for having a higher LCF, and thus higher display efficiency (at a specific comparable white point color coordinate).

[0128] After 1000 hours of flux testing, the changes in the optical parameters of the QD film are as follows:

[0129] • Change in y-value: from 0.149 to 0.058 (-0.091)

[0130] • Change in LCF: from 43% to 14% (-29%)

[0131] • Changes in green light emission wavelength: from 525nm to 521nm (-4nm)

[0132] • Changes in green FWHM: 0nm

[0133] These results indicate that, compared to Example 3, the higher haze of the QD film at high blue light flux leads to lower QD film stability (specifically, the y-value, LCF, and emission wavelength are all less stable). Therefore, low haze in the QD film is advantageous, resulting in improved QD film stability at high blue light flux, leading to stable color coordinates and a stable white point throughout the operating life of the display device.

[0134] Table 1. Summary of parameter changes after high-throughput testing in Experiment 3 and Comparative Example 1:

[0135]

[0136] The light-emitting element of the present invention is characterized by a lower haze (h1 = 50%) than that of the element in Comparative Example 1 (h2 = 98%). This data indicates that the embodiments of the present invention exhibit a more stable y value (higher film stability), a more stable LCF value, and a significantly increased LCF value overall.

[0137] Comparative Example 2 regarding Example 3: Features low haze and high T g Preparation of green light remote perovskite QD films.

[0138] The process is the same as in Example 3, except that the acrylate monomer mixture (0.7g FA-513AS, Hitachi Chemical, Japan / 0.3g Miramer M240, Miwon, Korea) is replaced with the following acrylate monomer mixture:

[0139] ·0.7g FA-DCPA, Hitachi Chemical, Japan / 0.3g FA-320M, Hitachi Chemical, Japan.

[0140] The resulting green perovskite QD film exhibited an emission wavelength of 526 nm, an FWHM of 22 nm, and a y-value of 0.153 (almost identical to the low-haze QD film in Experiment 3). The LCF of the QD film was 49%. The haze of the QD film was 51%, and the transmittance was 85%. The measured Tg of the UV-cured resin composition was 144 °C.

[0141] After 1000 hours of flux testing, the changes in the optical parameters of the QD film are as follows:

[0142] • Change in y-value: from 0.153 to 0.068 (-0.085)

[0143] • Change in LCF: from 49% to 21% (-28%)

[0144] • Changes in green light emission wavelength: from 526nm to 525nm (-1nm)

[0145] • Changes in green FWHM: 0nm

[0146] These results demonstrate that under high blue light flux, the solid polymer of the QD film (self-supporting film) exhibits high TL. g This leads to lower QD membrane stability. Therefore, QD membranes exhibit low TT. g This is advantageous, resulting in improved QD film stability under high blue light flux, so as to have stable color coordinates and stable white point throughout the operating life of the display device.

[0147] Table 2. Summary of parameter changes after high-throughput testing in Experiment 3 and Comparative Example 2:

[0148]

[0149] The light-emitting element of the present invention is characterized by T g (Tg=75℃) lower than the component in Comparative Example 2 (T g =144℃). This data indicates that the embodiments of the present invention exhibit a more stable y value and a more stable LCF value (higher film stability).

Claims

1. A light-emitting element comprising - The first LED light source (11) for emitting blue light (aa), - A second LED light source (12) for emitting red light (bb), - Emissive layer (100), containing - Solid polymer compositions, and - Green luminescent crystal (1) The glass transition temperature T of the solid polymer composition g The solid polymer composition comprises a polymer selected from acrylates (2) and has a Tg ≤ 80℃. The green luminescent crystal (1) is a perovskite crystal of formula (I'): FAPbBr3 (I'); - The light emitted by the first LED light source (11) and the second LED light source (12) passes through the light-emitting layer. - Wherein, when absorbing light emitted by the first LED light source (11), the green light-emitting crystal (1) emits light at a wavelength in the green light spectrum (cc), and - The haze h1 of the luminescent layer (100) is 30% < h1 < 70%.

2. The light-emitting element according to claim 1, wherein the concentration of Pb in the light-emitting layer (100) is 100-1000 ppm.

3. The light-emitting element according to claim 1 or 2, wherein the Pb loading of the light-emitting layer (100) is 5-200 mg / m³. 2 .

4. The light-emitting element according to claim 1 or 2, wherein the light-emitting layer (100) is disposed away from the first LED light source (11) and / or the second LED light source (12).

5. The light-emitting element according to claim 1 or 2, wherein the polymer (2) is characterized by a molar ratio z of the sum of (oxygen + nitrogen) to carbon, wherein z ≤ 0.

9.

6. The light-emitting element according to claim 1 or 2, wherein the polymer (2) is selected from cyclic aliphatic acrylates.

7. The light-emitting element according to claim 1 or 2, wherein the solid polymer composition comprises scattering particles selected from metal oxide particles and polymer particles.

8. The light-emitting element according to claim 1 or 2, wherein the light-emitting layer (100) forms a self-supporting film or a portion thereof.

9. The light-emitting element according to claim 1 or 2, wherein the light-emitting layer (100) is sandwiched between two barrier layers (101) to form a sandwich structure.

10. A light-emitting device comprising a light-emitting element according to any one of claims 1 to 9.

11. The light-emitting device according to claim 10, wherein the light-emitting element comprises - Array of light sources, and - Emissive layer (100) The array of light sources said therein includes more than one first LED light source (11) and more than one second LED light source (12).

12. The light-emitting device according to claim 10 or 11, comprising a diffuser plate or diffuser film (101) disposed between the array of the light source and the light-emitting layer (100).

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