Low refractive index molecules, materials and low refractive index thin films, light emitting devices

Abstract

The application relates to a low-refractive molecular, which is one of molecules represented by formula (I), formula (II) or formula (III): wherein R1 and R2 are substituents. The application solves the problem that the low-refractive material is poor in flexibility and cannot be evaporated in an electroluminescent device.

Description

Technical Field

[0001] This application relates to the field of light-emitting diodes, and more particularly to functional layer materials for light-emitting diodes. Background Technology

[0002] Organic light-emitting diodes (OLEDs) and quantum dot light-emitting diodes (QLEDs) are cutting-edge technologies in the display field. Both are electroluminescent devices, and their light-emitting principle involves the recombination of electrons and holes in the light-emitting layer, resulting in similar structures. Both types of LEDs can have their cathode and anode as the light-emitting side. The cathode is typically made of metals such as aluminum, magnesium, silver, or ytterbium, or their alloys, and has a high refractive index, significantly different from that of air. This results in a relatively small critical angle when light propagates from the cathode into the air, making total internal reflection more likely.

[0003] To increase the light extraction efficiency of top-emitting electroluminescent devices, a high-refractive-index layer is typically formed by adding a layer of material with a higher refractive index on a semi-transparent cathode to reduce total internal reflection. In recent years, researchers have proposed adding a low-refractive-index layer on top of the high-refractive-index layer to further improve light utilization. However, most existing low-refractive-index molecules are inorganic or polymeric materials, such as SiO2, SiON, and LiF, with refractive indices mostly between 1.3 and 1.6 for 460nm light. Inorganic materials have poor flexibility, which can lead to a shorter screen lifespan when the flexible screen is bent. While there are existing technologies using polymers to create low-refractive-index layers, polymers cannot be vapor-deposited and must be prepared from solutions, affecting subsequent packaging processes. Summary of the Invention

[0004] This application provides a low-refractive-index molecule, material, low-refractive-index thin film, and light-emitting device to solve the technical problems of poor flexibility and inability to vapor deposit low-refractive-index materials in existing electroluminescent devices.

[0005] In a first aspect, embodiments of this application provide a low-refractive-index molecule, wherein the low-refractive-index molecule is one of the molecules represented by formula (I), formula (II), or formula (III):

[0006]

[0007]

[0008] R1 and R2 are substituents.

[0009] In some embodiments of this application, R1 and R2 are each independently selected from one of halogen, nitro, nitrile, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkoxy, substituted or unsubstituted thioether, substituted or unsubstituted aryl, and substituted or unsubstituted heteroaryl.

[0010] In some embodiments of this application, R1 and R2 are each independently selected from one of the groups represented by formula (Ⅳ) or formula (Ⅴ):

[0011]

[0012] Ar1, Ar2, and Ar3 are substituents.

[0013] In some embodiments of this application, Ar1 to Ar3 are each independently selected from one of the following: halogen, nitro, nitrile, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkoxy, substituted or unsubstituted thioether, substituted or unsubstituted aryl, and substituted or unsubstituted heteroaryl.

[0014] In some embodiments of this application, Ar1 to Ar3 are each independently selected from one of the groups represented by free formula (VI):

[0015]

[0016] Each of the six X's is independently selected from either C or N;

[0017] Ar4 appears each time as one of the following: a hydrogen atom, a deuterium atom, a non-linked group, a linked group, or a direct bond.

[0018] n is an integer in the interval [1, 6].

[0019] In some embodiments of this application, Ar4 is, each time it appears, one of the following: hydrogen atom, deuterium atom, direct bond, halogen, nitro group, nitrile group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted thioether group, substituted or unsubstituted aryl group, or substituted or unsubstituted heteroaryl group.

[0020] In some embodiments of this application, Ar4 is, each time it appears, one of hydrogen atom, deuterium atom, direct bond, or alkyl group.

[0021] In some embodiments of this application, Ar1 to Ar3 are each independently selected from one of the following groups:

[0022]

[0023] In some embodiments of this application, the low refractive index molecule is one of the following molecules:

[0024]

[0025]

[0026]

[0027]

[0028] Secondly, embodiments of this application provide a low refractive index material, the low refractive index material comprising at least one of the low refractive index molecules described in any embodiment of the first aspect.

[0029] Thirdly, embodiments of this application provide a low refractive index thin film, wherein the material of the low refractive index thin film is the low refractive index material described in any embodiment of the second aspect.

[0030] Fourthly, embodiments of this application provide a light-emitting device, the light-emitting device comprising the low-refractive-index thin film described in any embodiment of the third aspect.

[0031] In some embodiments of this application, the light-emitting device is one of organic light-emitting diodes and quantum dot light-emitting diodes.

[0032] In some embodiments of this application, the light-emitting device includes:

[0033] anode;

[0034] A light-emitting layer disposed on the anode;

[0035] A cathode disposed on the light-emitting layer;

[0036] A high refractive index layer disposed on the cathode;

[0037] The low-refractive-index thin film disposed on the high-refractive-index layer.

[0038] The technical solutions provided in this application have the following advantages compared with the prior art:

[0039] The low refractive index molecule provided in this application has a molecular formula that conforms to one of formulas (I), (II), or (III), wherein formulas (I), (II), and (III) all have an adamantane structure, i.e. The adamantane structure consists of multiple alkyl groups linked together to form a complex spatial structure. On one hand, the electronic configurations of all carbon atoms in the adamantane structure are similar to those of methane carbon atoms, with the outermost electrons evenly distributed outside the nucleus and the carbon-carbon bond angles close to 109°28′. This makes the adamantane structure very stable, meaning the core structure of the low-refractive-index molecule described in this application is highly stable, and therefore it is not easily decomposed during vapor deposition. On the other hand, adamantane has multiple alkyl groups. From formulas (I), (II), and (III), it can be seen that the groups connected to both sides of the adamantane structure are linked by the... The adamantane structure consists of multiple saturated carbon atoms linked by carbon chains, with even the shortest chain containing three carbon atoms. This makes it difficult for the polarities of the groups on both sides of the adamantane structure to interfere with each other, thus contributing to the low polarity of the low-refractive-index molecule. Furthermore, the complex spatial structure of adamantane results in a relatively large volume for the low-refractive-index molecule, making it easier for materials formed from this molecule to possess a low optical refractive index. Finally, the low-refractive-index molecule is a small organic molecule, easily prepared into thin films via vapor deposition. The low-refractive-index molecules are bonded together by weak van der Waals forces in the formed film, giving it flexibility. Therefore, this application solves the problems of poor flexibility and inability to vapor deposit low-refractive-index materials in electroluminescent devices. Attached Figure Description

[0040] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0041] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the structure of the light-emitting device provided in the embodiments of this application. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] Unless otherwise specified, the terminology used herein should be understood as having the meaning as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In case of any conflict, this specification shall prevail.

[0045] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0046] Existing electroluminescent devices suffer from technical problems such as poor flexibility of low-refractive-index materials and the inability to vapor deposit them.

[0047] The technical solution provided in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0048] In a first aspect, embodiments of this application provide a low-refractive-index molecule, wherein the low-refractive-index molecule is one of the molecules represented by formula (I), formula (II), or formula (III):

[0049]

[0050] R1 and R2 are substituents.

[0051] When organic small molecules form a transparent thin film, the polarity of the organic small molecules and the refractive index of the film show a certain positive correlation.

[0052] The low-refractive-index molecule described in this application has a molecular formula that conforms to one of formulas (I), (II), or (III), wherein formulas (I), (II), and (III) all have an adamantane structure, i.e. The adamantane structure consists of multiple alkyl groups linked together to form a complex spatial structure. On one hand, the electronic configurations of all carbon atoms in the adamantane structure are similar to those of methane carbon atoms, with the outermost electrons evenly distributed outside the nucleus and the carbon-carbon bond angles close to 109°28′. This makes the adamantane structure very stable, meaning the core structure of the low-refractive-index molecule described in this application is highly stable, and therefore it is not easily decomposed during vapor deposition. On the other hand, adamantane has multiple alkyl groups. From formulas (I), (II), and (III), it can be seen that the groups connected to both sides of the adamantane structure are linked by the... The adamantane structure consists of multiple saturated carbon atoms linked by carbon chains, with even the shortest chain containing three carbon atoms. This makes it difficult for the polarities of the groups on both sides of the adamantane structure to interfere with each other, thus contributing to the low polarity of the low-refractive-index molecule. Furthermore, the complex spatial structure of adamantane results in a relatively large volume for the low-refractive-index molecule, making it easier for materials formed from this molecule to possess a low optical refractive index. Finally, the low-refractive-index molecule is a small organic molecule, easily prepared into thin films via vapor deposition. The low-refractive-index molecules are bonded together by weak van der Waals forces in the formed film, giving it flexibility. Therefore, this application solves the problems of poor flexibility and inability to vapor deposit low-refractive-index materials in electroluminescent devices.

[0053] In this application, the R1 or R2 group is connected to the adamantane structure via an ester group, an oxygen atom, or a peptide bond. These three structural uses also help to reduce the overall polarity of the low-refractive-index molecule.

[0054] In some embodiments of this application, R1 and R2 are each independently selected from one of halogen, nitro, nitrile, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkoxy, substituted or unsubstituted thioether, substituted or unsubstituted aryl, and substituted or unsubstituted heteroaryl.

[0055] In some embodiments of this application, R1 and R2 are each independently selected from one of the groups represented by formula (Ⅳ) or formula (Ⅴ):

[0056]

[0057] Ar1, Ar2, and Ar3 are substituents.

[0058] It should be noted that in this application The symbol refers to the connection point, that is, R1 and R2 are connected through the... The symbol is located at a point that is connected to an O atom or a carbonyl group in formula (I), formula (II), or formula (III).

[0059] The beneficial effect of setting benzene rings in R1 and R2 is to increase the stability of the ground refractive index molecule.

[0060] The beneficial effect of Ar1, Ar2, and Ar3 being attached to the benzene ring via phosphoxy or silyl groups is that the transfer of polarity by the phosphoxy or silyl groups is also very weak, which can keep the R1 and R2 groups low in polarity.

[0061] In some embodiments of this application, Ar1 to Ar3 are each independently selected from one of the following: halogen, nitro, nitrile, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkoxy, substituted or unsubstituted thioether, substituted or unsubstituted aryl, and substituted or unsubstituted heteroaryl.

[0062] In some embodiments of this application, Ar1 to Ar3 are each independently selected from one of the groups represented by free formula (VI):

[0063]

[0064] Each of the six X's is independently selected from either C or N;

[0065] Ar4 appears each time as one of the following: a hydrogen atom, a deuterium atom, a non-linked group, a linked group, or a direct bond.

[0066] n is an integer in the interval [1, 6].

[0067] The meaning of 'n' is the substitution number. This is easy to understand. There are a maximum of 6 substitution sites on the unit. Each X may be connected to a substituent, so a maximum of 6 Ar1s can be connected. That is, n is an integer in the interval [1, 6], which represents the number of Ar1 substitutions.

[0068] Easy to understand The unit interacts with the non-refractive index molecules via Ar1. Partial connection of units, in which case Ar1 is a linking group, or a direct bond.

[0069] It is readily understood that in this application, the linking group refers to a group having two unbonded electrons, such as -CH2-. The non-linking group refers to a group having one unbonded electron, such as -CH3.

[0070] Formula (VI) may contain only one aromatic ring and no other aromatic structures, that is, it may contain only one aromatic ring. This unit has an aromatic structure. In this case, the starting materials related to formula (IX) are easier to obtain in the synthesis of low refractive index molecules, and the difficulty of the corresponding synthetic steps is also reduced.

[0071] In some embodiments of this application, Ar4 is, each time it appears, one of the following: hydrogen atom, deuterium atom, direct bond, halogen, nitro group, nitrile group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted thioether group, substituted or unsubstituted aryl group, or substituted or unsubstituted heteroaryl group.

[0072] In some embodiments of this application, Ar4 is, each time it appears, one of hydrogen atom, deuterium atom, direct bond, or alkyl group.

[0073] In some embodiments of this application, Ar1 to Ar3 are each independently selected from one of the following groups:

[0074]

[0075] In some embodiments of this application, the low refractive index molecule is one of the following molecules:

[0076]

[0077]

[0078]

[0079]

[0080]

[0081] Secondly, embodiments of this application provide a low refractive index material, the low refractive index material comprising at least one of the low refractive index molecules described in any embodiment of the first aspect.

[0082] It is easy to understand that the low refractive index material may be composed entirely of the low refractive index molecules, or it may be composed of most of the low refractive index molecules and a small amount of other additives.

[0083] The low refractive index material described in this application is based on the low refractive index molecules described in the first aspect. Specific implementations of the low refractive index material can be referred to the embodiments of the first aspect and common knowledge in the art. Since the low refractive index material adopts all the technical solutions of the embodiments of the first aspect, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0084] Thirdly, embodiments of this application provide a low refractive index thin film, wherein the material of the low refractive index thin film is the low refractive index material described in any embodiment of the second aspect.

[0085] The low refractive index thin film described in this application is based on the low refractive index material described in the second aspect. The specific implementation of the low refractive index thin film can be referred to the embodiments of the second aspect and common knowledge in the art. Since the low refractive index thin film adopts all the technical solutions of the embodiments of the second aspect, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0086] Fourthly, embodiments of this application provide a light-emitting device, the light-emitting device comprising the low-refractive-index thin film described in any embodiment of the third aspect.

[0087] The light-emitting device described in this application is based on the low refractive index thin film described in the third aspect. The specific implementation of the light-emitting device can be referred to the embodiments of the third aspect and common knowledge in the art. Since the light-emitting device adopts all the technical solutions of the third aspect embodiments, it has at least all the beneficial effects brought about by the technical solutions of the third aspect embodiments, which will not be repeated here.

[0088] In some embodiments of this application, the light-emitting device is one of organic light-emitting diodes and quantum dot light-emitting diodes.

[0089] Please refer to Figure 1 As will be understood by those skilled in the art, both organic light-emitting diodes and quantum dot light-emitting diodes include a light-emitting layer 6.

[0090] For organic light-emitting diodes, the material of the light-emitting layer 6 is an organic light-emitting material. The organic light-emitting material is an organic light-emitting material known in the art, and may be selected from, but is not limited to, diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives or fluorene derivatives, TBPe fluorescent material emitting blue light, TTPA fluorescent material emitting green light, TBRb fluorescent material emitting orange light, and DBP fluorescent material emitting red light.

[0091] For quantum dot light-emitting diodes, the material of the light-emitting layer 6 is a quantum dot luminescent material. The quantum dot luminescent material can be any of the luminescent quantum dots known in the art, such as red quantum dots, green quantum dots, and blue quantum dots. The quantum dots can be selected from, but are not limited to, at least one of single-structure quantum dots and core-shell structure quantum dots. For example, the quantum dots can be selected from, but are not limited to, one or more of group II-VI compounds, group III-V compounds, and group I-III-VI compounds. As an example, group II-VI compounds may be selected from, but are not limited to, one or more of CdSe, CdS, CdTe, ZnSe, ZnS, CdTe, ZnTe, CdZnS, CdZnSe, CdZnTe, ZnSeS, ZnSeTe, ZnTeS, CdSeS, CdSeTe, CdTeS; CdZnSeS, CdZnSeTe, and CdZnSTe; group III-V compounds may be selected from, but are not limited to, one or more of InP, InAs, GaP, GaAs, GaSb, AlN, AlP, InAsP, InNP, InNSb, GaAlNP, and InAlNP; and group I-III-VI compounds may be selected from, but are not limited to, CuInS2.

[0092] Please refer to some embodiments of this application. Figure 1 The light-emitting device includes:

[0093] Anode 2;

[0094] Light-emitting layer 6 is disposed on the anode;

[0095] A cathode 10 is disposed on the light-emitting layer;

[0096] The low-refractive-index thin film disposed on the cathode.

[0097] Those skilled in the art will understand that light-emitting devices generally also include a substrate. Please refer to... Figure 1 The light-emitting device includes:

[0098] Substrate 1;

[0099] Anode 2 is disposed on the substrate 1;

[0100] The light-emitting layer 6 is disposed on the anode 2;

[0101] A cathode 10 is disposed on the light-emitting layer 6;

[0102] A high refractive index layer 11 is disposed on the cathode 10;

[0103] The low-refractive-index thin film disposed on the high-refractive-index layer 11.

[0104] Those skilled in the art will understand that the low refractive index thin film described in this application is generally applicable to top-mounted emitting devices.

[0105] Those skilled in the art will understand that the substrate 1 can be a transparent rigid or flexible material, such as glass, polyimide, etc., which can realize rigid substrate display and flexible display.

[0106] Those skilled in the art will understand that the materials of the anode 2 and the cathode 10 can be one or more of metals, carbon materials, and metal oxides. Metals can be, for example, one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, and Mg. Carbon materials can be, for example, one or more of graphite, carbon nanotubes, graphene, and carbon fibers. Metal oxides can be doped or undoped metal oxides, including one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, and AMO, as well as composite electrodes with metal sandwiched between doped or undoped transparent metal oxides.

[0107] Those skilled in the art will understand that the material of the high refractive index layer 11 may be selected from at least one of bis(aryl)amine derivatives and mono(aryl)amine derivatives.

[0108] In some embodiments of this application, the light-emitting device further includes at least one of hole injection layer 3, hole transport layer 4, electron transport layer 8, and electron injection layer 9.

[0109] Those skilled in the art will understand that the material of the hole injection layer 3 is a material known in the art for use in hole injection layers. The material of the hole injection layer 3 may be selected from materials with hole injection capability, including but not limited to poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinone-dimethylethane (F4-TCNQ), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzphenanthrene (HATCN), copper polyester carbonate (CuPc), transition metal oxides, and transition metal chalcogenides.

[0110] Those skilled in the art will understand that the material of the hole transport layer 4 can be selected from organic materials with hole transport capabilities, including but not limited to poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB), polyvinylcarbazole (PVK), poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (poly-TPD), poly(9,9-dioctylfluorene-co-bis-N,N-phenyl-1,4-phenylenediamine) (PFB), and 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCATA). The hole transport layer may be selected from one or more of the following: 4,4'-bis(9-carbazole)biphenyl (CBP), N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), doped graphene, undoped graphene, and C60. The hole transport layer material may also be selected from inorganic materials with hole transport capabilities, including but not limited to one or more of doped or undoped NiO, WO3, MoO3, and CuO.

[0111] Those skilled in the art will understand that the electron transport layer includes an electron transport material, which includes, but is not limited to, at least one of ZnO, TiO2, Cs2CO3, or 8-hydroxyquinoline aluminum (Alq3).

[0112] Those skilled in the art will understand that the electron injection layer 9 material includes at least one of Li2O, K2SiO3, LiF, Yb, Mg, and Ca.

[0113] In some embodiments of this application, the light-emitting device further includes at least one of a hole blocking layer 7 and an electron blocking layer 5.

[0114] Those skilled in the art will understand that the electron blocking layer 5 has hole transport characteristics and can be a red light-emitting auxiliary layer, a green light-emitting auxiliary layer, or a blue light-emitting auxiliary layer. The material of the electron blocking layer 5 can be an aromatic amine or carbazole material, such as 4,4-bis(9-carbazole)biphenyl (CBP), 9-phenyl-3-[4-(10-phenyl-9-anthrayl)phenyl]-9H-carbazole (PCzPA), etc. The thickness of the electron blocking layer 5 can be 5 to 50 nm.

[0115] Those skilled in the art will understand that the hole-blocking layer 7 includes at least one of an aromatic heterocyclic compound and a compound having phosphine oxide substituents on the heterocycle. The aromatic heterocyclic compound may be, for example, an imidazole derivative such as benzimidazole derivative, imidazopyridine derivative, or benzimidazolephenanthridine derivative, or a azine derivative such as a pyrimidine derivative or a triazine derivative, or a compound containing a nitrogen-containing six-membered ring structure such as a quinoline derivative, isoquinoline derivative, or phenanthreneroline derivative, having phosphine oxide substituents on the heterocycle. Compounds such as these can be 2,2'-(1,3-phenyl)bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazole] (OXD-7), 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenyl)-1,2,4-triazole (TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenyl)-1,2,4-triazole (p-EtTAZ), phenanthroline (BPhen), bromocresol purple (BCP), etc.

[0116] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0117] Example 1

[0118] This embodiment provides the compound numbered 1 in this application.

[0119] This embodiment also provides a method for preparing the compound, including the following steps:

[0120] Under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 2 and 0.22 mol of intermediate 1 were added, and the reaction was carried out at 80 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was obtained. After concentration, it was heated, a small amount of ethanol was added, and it was allowed to stand at room temperature for recrystallization. The mixture was filtered and washed with ethanol to obtain the recrystallized solid, which was intermediate 3.

[0121] Subsequently, under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 4 and 0.22 mol of intermediate 5 were added, and the reaction was carried out at 80 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was obtained. After concentration, it was heated, a small amount of ethanol was added, and it was allowed to stand at room temperature for recrystallization. The mixture was filtered and washed with ethanol to obtain the recrystallized solid, which yielded intermediate 6.

[0122] Subsequently, under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 6 and 0.102 mol of intermediate 7 were added, and the reaction was carried out at 80 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was obtained. After concentration, it was heated, a small amount of ethanol was added, and it was allowed to stand at room temperature for recrystallization. The mixture was filtered and washed with ethanol to obtain the recrystallized solid, which yielded intermediate 8.

[0123] Subsequently, under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 3 and 0.22 mol of intermediate 8 were added, and the reaction was carried out at 135 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was concentrated, heated, and a small amount of ethanol was added. The mixture was allowed to stand at room temperature for recrystallization, filtered under vacuum, and washed with ethanol to obtain the recrystallized solid, yielding compound 1.

[0124] The molecular structures of each intermediate are as follows:

[0125]

[0126] Mass spectrometry and nuclear magnetic resonance (NMR) tests were performed on compound 1, and the results are as follows:

[0127] Mass spectrometry m / z: 1564.72, elemental composition (%): C108H150N2O2Si2, C, 82.91; H, 9.66; N, 1.79; O, 2.05; Si, 3.59.

[0128] 1H NMR (300MHz, DMSO): 8.09(4H), 7.84(2H), 7.64(4H), 7.55(6H), 7.39(12H), 1.97(1H), 1.71-1.715(5H), 1.45-1.5(7H), 1.32(108H), 1.195(1H).

[0129] Please refer to Figure 1 This embodiment also provides a light-emitting device having the following structure:

[0130] Substrate 1 / Anode 2 / Hole injection layer 3 (10nm) / Hole transport layer 4 (110nm) / Electron blocking layer 5 (5nm) / Light emitting layer 6 (20nm) / Hole blocking layer 7 (5nm) / Electron transport layer 8 (30nm) / Electron injection layer 9 (1nm) / Cathode 10 (13nm) / High refractive index layer 11 (50nm) / Low refractive index layer 12 (50nm)

[0131] In this design, substrate 1 is made of polyimide, anode 2 is made of indium tin oxide (ITO), hole injection layer 3 is a mixture of m-MTDATA and F4TCNQ in a 97:3 mass ratio, hole transport layer 4 is made of m-MTDATA, electron blocking layer 5 is made of CBP, light-emitting layer 6 is a mixture of BH and BD in a 19:1 mass ratio, hole blocking layer 7 is made of TPBI, electron transport layer 8 is a mixture of BCP and lithium hydroxyquinoline (Liq) in a 1:1 mass ratio, electron injection layer 9 is made of Yb, cathode 10 is made of silver-magnesium alloy, high refractive index layer 11 is made of CP1, and low refractive index layer 12 is made of compound number 4. The structural formulas of the compounds involved are as follows:

[0132]

[0133] The light-emitting device described in this embodiment is prepared through the following steps:

[0134] The glass substrate 1 containing ITO was ultrasonically treated in a cleaning agent, rinsed in deionized water, ultrasonically degreased in an acetone-ethanol mixed solvent, and baked in a clean environment until all moisture was removed.

[0135] Place the PI substrate containing ITO in a vacuum chamber and evacuate it to 1×10⁻⁶. -5 ~1×10 -6 Hole injection material is vacuum-deposited on the side of ITO away from the PI substrate to form hole injection layer 3;

[0136] Hole transport material is vapor-deposited on the side of hole injection layer 3 away from ITO to form hole transport layer 4;

[0137] On the side of the hole transport layer 4 away from the hole injection layer 3, the material of the electron blocking layer is vacuum evaporated to form the electron blocking layer 5;

[0138] On the side of the electron blocking layer 5 away from the hole transport layer 4, the material of the light-emitting layer is vacuum evaporated to form the light-emitting layer 6;

[0139] On the side of the light-emitting layer 6 away from the electron blocking layer 5, the material of the hole blocking layer is vacuum evaporated to form the hole blocking layer 7;

[0140] On the side of the hole blocking layer 7 away from the light-emitting layer 6, the material of the electron transport layer is vacuum evaporated to form the electron transport layer 8.

[0141] On the side of the electron transport layer 8 away from the hole blocking layer 7, the material of the electron injection layer is vacuum evaporated to form the electron injection layer 9.

[0142] A cathode 10 is formed by plating a silver-magnesium alloy on the side of the electron injection layer 9 away from the electron transport layer 8;

[0143] A high refractive index layer 11 is formed by vapor deposition of a material on the side of the cathode 10 away from the electron injection layer 9;

[0144] The material of the low refractive index layer 12 is vapor-deposited on the side of the high refractive index layer 11 away from the cathode 10 to form the low refractive index layer 12.

[0145] Example 2

[0146] The only difference between this embodiment and Embodiment 1 is that:

[0147] This embodiment provides the compound numbered 2 in this application.

[0148] This embodiment also provides a method for preparing the compound, including the following steps:

[0149] Under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 14 and 0.22 mol of intermediate 13 were added, and the reaction was carried out at 80 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, the mixture was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was concentrated, heated, and a small amount of ethanol was added. The mixture was allowed to stand at room temperature for recrystallization, filtered under vacuum, and washed with ethanol to obtain the recrystallized solid, which yielded intermediate 15.

[0150] Subsequently, under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 15 and 0.22 mol of intermediate 16 were added, and the reaction was carried out at 80 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was concentrated, heated, and a small amount of ethanol was added. The mixture was allowed to stand at room temperature for recrystallization, filtered under vacuum, and washed with ethanol to obtain the recrystallized solid, which yielded intermediate 17.

[0151] Subsequently, under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 17 and 0.22 mol of intermediate 18 were added, and the reaction was carried out at 80 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was concentrated, heated, and a small amount of ethanol was added. The mixture was allowed to stand at room temperature for recrystallization, filtered under vacuum, and washed with ethanol to obtain the recrystallized solid, which yielded intermediate 19.

[0152] Subsequently, under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 19 and 0.42 mol of intermediate 5 were added, and the reaction was carried out at 80 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was obtained. After concentration, it was heated, a small amount of ethanol was added, and it was allowed to stand at room temperature for recrystallization. The mixture was filtered and washed with ethanol to obtain the recrystallized solid, which yielded compound 2.

[0153] The molecular structures of each intermediate are as follows:

[0154]

[0155]

[0156] The obtained compound 2 was subjected to mass spectrometry and nuclear magnetic resonance tests, and the results are as follows:

[0157] Mass spectrometry m / z: 1225.67, elemental composition (%): C80H106O6P2, C, 78.4; H, 8.72; O, 7.83, P, 5.05.

[0158] 1H NMR (300MHz, DMSO): 7.7-7.77(8H), 7.62(8H), 7.35(4H), 2.15(1H), 1.895(1H), 1.79(4H), 1.45-1.545(7H), 1.32(72H), 1.195(1H).

[0159] Example 3

[0160] The only difference between this embodiment and Embodiment 1 is that:

[0161] This embodiment provides the compound numbered 3 in this application.

[0162] This embodiment also provides a method for preparing the compound, including the following steps:

[0163] Under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 14 and 0.22 mol of intermediate 20 were added, and the reaction was carried out at 80 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, the mixture was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was concentrated, heated, and a small amount of ethanol was added. The mixture was allowed to stand at room temperature for recrystallization, filtered under vacuum, and washed with ethanol to obtain the recrystallized solid, which yielded intermediate 21.

[0164] Subsequently, under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 21 and 0.22 mol of intermediate 16 were added, and the reaction was carried out at 135 °C. A 100W tungsten filtrate bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was concentrated, heated, and a small amount of ethanol was added. The mixture was allowed to stand at room temperature for recrystallization, filtered under vacuum, and washed with ethanol to obtain the recrystallized solid, which yielded intermediate 22.

[0165] Subsequently, under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 22 and 0.22 mol of intermediate 18 were added, and the reaction was carried out at 80 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was obtained. After concentration, it was heated, a small amount of ethanol was added, and it was allowed to stand at room temperature for recrystallization. The mixture was filtered and washed with ethanol to obtain the recrystallized solid, which yielded intermediate 23.

[0166] Subsequently, under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 23 and 0.22 mol of intermediate 5 were added, and the reaction was carried out at 80 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was concentrated, heated, and a small amount of ethanol was added. The mixture was allowed to stand at room temperature for recrystallization, filtered under vacuum, and washed with ethanol to obtain the recrystallized solid, yielding compound 17.

[0167] The molecular structures of each intermediate are as follows:

[0168]

[0169] The obtained compound 17 was subjected to mass spectrometry and nuclear magnetic resonance analysis, and the results are as follows:

[0170] Mass spectrometry m / z: 1197.7, elemental composition (%): C80H110O4P2, C, 80.23; H, 9.26; O, 5.34, P, 5.17.

[0171] 1H NMR (300MHz, DMSO): 7.8(4H),7.62-7.7(12H),7.48(4H),4.8(4H),1.7(1H),1.

[0172] 45-1.57(8H),1.32-1.325(76H),1.195(1H).

[0173] Example 4

[0174] The only difference between this embodiment and Embodiment 1 is that:

[0175] This embodiment provides the compound numbered 4 in this application.

[0176] This embodiment also provides a method for preparing the compound, including the following steps:

[0177] Under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 2 and 0.22 mol of intermediate 1 were added, and the reaction was carried out at 80 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was obtained. After concentration, it was heated, a small amount of ethanol was added, and it was allowed to stand at room temperature for recrystallization. The mixture was filtered and washed with ethanol to obtain the recrystallized solid, which was intermediate 3.

[0178] Subsequently, under visible light irradiation, in the presence of tetra(triphenylphosphine)palladium in a Ba(OH)₂ / 95% EtOH solvent mixture, 0.1 mol of intermediate 9 and 0.22 mol of intermediate 10 were added and reacted at 80 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filament bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was obtained. After concentration, it was heated, a small amount of ethanol was added, and it was allowed to stand at room temperature for recrystallization. The mixture was filtered and washed with ethanol to obtain the recrystallized solid, which yielded intermediate 11.

[0179] Subsequently, under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 11 and 0.102 mol of intermediate 7 were added, and the reaction was carried out at 80 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was concentrated, heated, and a small amount of ethanol was added. The mixture was allowed to stand at room temperature for recrystallization, filtered under vacuum, and washed with ethanol to obtain the recrystallized solid, which yielded intermediate 12.

[0180] Subsequently, under visible light irradiation, in a Ba(OH)₂ / 95% EtOH solvent mixture, in the presence of tetra(triphenylphosphine)palladium, 0.1 mol of intermediate 3 and 0.22 mol of intermediate 12 were added, and the reaction was carried out at 135 °C. A 100W tungsten filament bulb was used as the irradiation source, and the reaction flask was immersed in a water bath to isolate the heat transfer from the tungsten filtrate bulb. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was concentrated, heated, and a small amount of ethanol was added. The mixture was allowed to stand at room temperature for recrystallization, filtered under vacuum, and washed with ethanol to obtain the recrystallized solid, yielding compound 31.

[0181] The molecular structures of each intermediate are as follows:

[0182]

[0183]

[0184] The obtained compound 6 was subjected to mass spectrometry and nuclear magnetic resonance analysis, and the results are as follows:

[0185] Mass spectrometry m / z: 891.27, elemental composition (%): C60H54N2O2Si2, C, 80.86; H, 6.11; N, 3.14, O, 3.59, Si, 6.30.

[0186] 1H NMR (300MHz, DMSO): 8.09(4H), 7.64-7.84(6H), 7.46(12H), 7.38(18H), 1.97(1H), 1.71-1.715(5H), 1.45-1.455(5H), 1.5(2H), 1.195(1H).

[0187] Example 5

[0188] The only difference between this embodiment and Embodiment 1 is that:

[0189] This embodiment provides the compound numbered 5 in this application.

[0190] Example 6

[0191] The only difference between this embodiment and Embodiment 1 is that:

[0192] This embodiment provides the compound numbered 6 in this application.

[0193] Example 7

[0194] The only difference between this embodiment and Embodiment 1 is that:

[0195] This embodiment provides the compound numbered 7 in this application.

[0196] Example 8

[0197] The only difference between this embodiment and Embodiment 1 is that:

[0198] This embodiment provides the compound numbered 8 in this application.

[0199] Example 9

[0200] The only difference between this embodiment and Embodiment 1 is that:

[0201] This embodiment provides the compound numbered 9 in this application.

[0202] Example 10

[0203] The only difference between this embodiment and Embodiment 1 is that:

[0204] This embodiment provides the compound numbered 10 in this application.

[0205] Example 11

[0206] The only difference between this embodiment and Embodiment 1 is that:

[0207] This embodiment provides the compound numbered 11 in this application.

[0208] Example 12

[0209] The only difference between this embodiment and Embodiment 1 is that:

[0210] This embodiment provides the compound numbered 12 in this application.

[0211] Example 13

[0212] The only difference between this embodiment and Embodiment 1 is that:

[0213] This embodiment provides the compound numbered 13 in this application.

[0214] Example 14

[0215] The only difference between this embodiment and Embodiment 1 is that:

[0216] This embodiment provides the compound numbered 14 in this application.

[0217] Example 15

[0218] The only difference between this embodiment and Embodiment 1 is that:

[0219] This embodiment provides the compound numbered 15 in this application.

[0220] Example 16

[0221] The only difference between this embodiment and Embodiment 1 is that:

[0222] This embodiment provides the compound numbered 16 in this application.

[0223] Example 17

[0224] The only difference between this embodiment and Embodiment 1 is that:

[0225] This embodiment provides the compound numbered 17 in this application.

[0226] Example 18

[0227] The only difference between this embodiment and Embodiment 1 is that:

[0228] This embodiment provides the compound numbered 18 in this application.

[0229] Example 19

[0230] The only difference between this embodiment and Embodiment 1 is that:

[0231] This embodiment provides the compound numbered 19 in this application.

[0232] Example 20

[0233] The only difference between this embodiment and Embodiment 1 is that:

[0234] This embodiment provides the compound numbered 20 in this application.

[0235] Example 21

[0236] The only difference between this embodiment and Embodiment 1 is that:

[0237] This embodiment provides the compound numbered 21 in this application.

[0238] Example 22

[0239] The only difference between this embodiment and Embodiment 1 is that:

[0240] This embodiment provides compound number 22 in this application.

[0241] Example 23

[0242] The only difference between this embodiment and Embodiment 1 is that:

[0243] This embodiment provides the compound numbered 23 in this application.

[0244] Comparative Example 1

[0245] This comparative example provides a light-emitting device, which differs from the light-emitting device described in Example 1 only in that:

[0246] The material of the low refractive index layer 12 is LiF.

[0247] Relevant experimental and effect data:

[0248] Compounds numbered 1 to 21 were prepared into thin films, and their refractive indices for 450 nm light were tested. The results are shown in Table 1.

[0249] serial number Refractive index serial number Refractive index 1 1.543 2 1.539 3 1.539 4 1.538 5 1.536 6 1.535 7 1.531 8 1.525 9 1.528 10 1.525 11 1.573 12 1.579 13 1.586 14 1.706 15 1.712 16 1.721 17 1.530 18 1.531 19 1.533 20 1.546 21 1.543

[0250] Table 1

[0251] As can be easily seen from Table 1, compounds numbered 1 to 21 all exhibit low refractive indices.

[0252] The external quantum efficiency (EQE) and lifetime of the light-emitting devices in Examples 1, 2, 3, 20, and 23 were tested, and the results are shown in Table 2.

[0253]

[0254]

[0255] Table 2

[0256] LT95@1000nit refers to the time required for the device to decay to 950nit brightness from an initial brightness of 1000nit. All lifetime measurements were taken after 21 days of storage.

[0257] As can be easily seen from Table 2, the EQE of Examples 1, 2, 3, 20, and 23 is generally higher than that of the comparative examples. The increase in EQE implies an increase in light extraction efficiency. The only difference between Examples 1, 2, 3, 20, and 23 and the comparative examples is the different low-refractive-index layers. This indicates that the increase in EQE of Examples 1, 2, 3, 20, and 23 is due to the use of different materials to prepare the low-refractive-index layers. Since the refractive indices of compounds numbered 1 to 12 are all similar, it is reasonable to believe that compounds numbered 1 to 12 are more conducive to improving EQE than existing LiF as materials for the low-refractive-index layers.

[0258] The lifetimes of Examples 1, 2, 3, 20, and 23 are generally higher than those of the comparative examples. This may be because, under the same initial brightness of 1000 nits, the different light extraction efficiencies lead to different loss efficiencies of the light-emitting layer material.

[0259] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0260] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. For associations involving three or more related objects described using "and / or", it indicates that any one of the three related objects can exist alone, or at least two of them can exist simultaneously. For example, for A, and / or B, and / or C, it can mean that any one of A, B, and C exists alone, or any two of them exist simultaneously, or all three of them exist simultaneously. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or multiple.

[0261] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A low-refractive-index molecule, characterized in that, The low-refractive-index molecule is one of the following molecules: , , .

2. A low refractive index material, characterized in that, The low-refractive-index material includes at least one of the low-refractive-index molecules described in claim 1.

3. A low refractive index thin film, characterized in that, The material of the low-refractive-index thin film is the low-refractive-index material as described in claim 2.

4. A light-emitting device, characterized in that, The light-emitting device includes the low-refractive-index thin film as described in claim 3.

5. The light-emitting device according to claim 4, characterized in that, The light-emitting device is one of organic light-emitting diodes or quantum dot light-emitting diodes.

6. The light-emitting device according to claim 4, characterized in that, The light-emitting device includes: anode; A light-emitting layer disposed on the anode; A cathode disposed on the light-emitting layer; A high refractive index layer disposed on the cathode; The low-refractive-index thin film disposed on the high-refractive-index layer.

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