Formulations for producing optical layers containing metal oxides

Abstract

The invention relates to a formulation for producing an optical layer containing a metal oxide. The formulation may exhibit at least one of properties as a higher material or as a high performance material. The formulations may be used in nanotechnology processes to fabricate semiconductor device / display device applications, such as semiconductor chips, or liquid crystals, quantum dots, OLED displays fabricated on semiconductor controlled substrates.

Description

Technical Field

[0001] This invention relates to a formulation for preparing an optical layer containing a metal oxide, a method for preparing the formulation, the use of the formulation, a method for preparing a composite material, composite materials, optical devices, and display devices. Background Technology

[0002] Cutting-edge optical devices typically include optical gratings made of composite materials having a supporting substrate and a complex, interwoven pattern thereon, consisting of different layers or stacks of layers. Creating such complex, interwoven patterns usually requires structuring processes, which become increasingly challenging as the size of the structures to be fabricated decreases.

[0003] Besides their wide range of applications, such as in spectrometers or optical storage systems (CDs, DVDs, etc.), diffraction gratings are also a core component of so-called XR devices (usually in the form of glasses). In this context, R stands for the term "reality," and X represents different attributes such as virtual, augmented, mixed, etc. Therefore, diffraction gratings form a core part of the so-called optical engine in XR devices, specifically in augmented reality and mixed reality glasses. Virtual reality glasses, when built as head-mounted displays, typically consist of conventional liquid crystal (LC) organic light-emitting diode (OLED) displays embedded in devices directly in front of the user's eyes, and therefore do not necessarily require diffraction gratings. In contrast, augmented reality and mixed reality glasses are designed to allow consumers to receive a visual impression of their environment, ideally as if they were not wearing any glasses at all. However, they also provide and serve digital information and project it into the individual's field of vision. Additional digital information is collected from the identification and analysis of the environment for personal inspection or viewing. To enable the transmission and projection of supporting digital information into an individual's eyes, augmented reality or mixed reality glasses are equipped with an information supply unit coupled to an optical waveguide system through which optically encoded supporting information is directly transmitted to the lenses of the glasses. Here, the information passes through a diffraction grating that couples the incident light into the lens and splits it according to its angular information and spectral bands via diffraction. After the optical coupling input, the lens acts as a waveguide, allowing light to travel to and enter the individual's pupil. The location of the optical coupling input is independent of any preferred location and therefore irrelevant to technical requirements. The direction of light travel within the lens is determined by a diffraction grating that diffracts or splits the light. At specific locations on the lens, second and third diffraction gratings are used to change the direction of light travel, thereby forcing the light to be projected into the user's pupil. Light travels through the glasses via total internal reflection (TIR), thus bouncing several times between the eyepiece interfaces until reaching another diffraction grating, thereby changing the internal TIR direction of the light (see...). Figure 2The second and third gratings are geometrically aligned in different directions relative to the first and coupled gratings, for example, by a specific angular distortion along the longitudinal axis, thereby allowing for a change in the propagation direction of the total internal reflection light. Needless to say, the lens itself or the material used to manufacture the lens should not be light-absorbing. Otherwise, the supporting information will never reach the user's pupil, or will only reach the user's pupil under conditions of strong light depletion. This process is effective regardless of whether a reflective or transmissive grating is used. Typically, lenses are equipped with two types of gratings to properly guide light. It should also be mentioned that there are differences in the optical performance of reflective and transmissive gratings; however, these are no longer of interest in the context of this invention. The basic structure of the gratings is very similar, which is more important at this point.

[0004] However, different designs and structures exist for waveguides, such as surface relief (SR) or volume holographic (VPH) gratings. The two types are very similar in appearance. In the simplest case, the grating is fixed to the surface of the waveguide material (here, a lens). The grating itself consists of an array of fine structures, primarily, but not limited to, trenches of a first material type 01 with a refractive index RI 01. The geometry of the trenches can vary widely, from rectangular to V-shaped, U-shaped, and so on. The width (including structures of different widths), the geometry of the trenches, their spacing, and their depth (including different depths) are all specifically designed to influence the diffraction pattern of the incident light to be diffracted.

[0005] In the case of a VPH grating, the grooves or structures of a first material type (material 01) having a refractive index (RI 01) are filled with a second material type (material 02) having a refractive index (RI 02), wherein the difference between RI 02 and RI 01 is increasing (see...). Figure 1 and Figure 3 For completeness, it should be mentioned that material 01 or material 02 can be composed of a stack of structured layers, each containing a different material composition with different refractive indices, stacked on top of each other to form material 01 or material 02 with an effective refractive index or a graded refractive index RI 01 or RI 02, respectively. Incidentally, the (effective or graded) refractive indices RI 01 and RI 02 depend on the refractive index of the waveguide or lens that makes up the eyeglasses. If a glass lens with a high refractive index (n03 > 1.46) is used, the (effective or graded) refractive indices of material 01 and material 02 are considered to be higher than the (effective or graded) refractive index of the lens itself, thus achieving and exceeding an RI value of 2.0. Surface relief (SR) gratings can look similar and may also include a second type of material as a filler for the trenches, but the trenches may also be just air. High-performance gratings, especially VPH type gratings, can be fabricated using standard photolithography and deposition techniques known from microfabrication such as integrated circuit manufacturing.

[0006] These standard techniques typically include physical vapor deposition (PVD) or chemical vapor deposition (CVD) processes, and due to unfavorable deposition and / or layer growth characteristics, including increased deposition and / or growth rates at corners and edges, incomplete gap filling is often resulted. This incomplete gap filling leads to the formation of voids within the structure to be filled by the PVD and CVD materials. In addition to void formation, the substrate surface is also covered by PVD and / or CVD layers, the thickness of which is almost the same as the maximum depth of the deepest structure to be filled by the deposited gap-filling material (see...). Figure 4 and Figure 5 However, in some applications, it may be necessary to expose the surface of the substrate so that it can be used for further processing. Therefore, it is necessary to remove unwanted capping layers from PVD or CVD, for example by chemical mechanical planarization (CMP), without damaging the underlying pristine substrate surface. While CMP has been used in the fabrication of integrated circuits for a long time, it is a time-consuming and expensive process and can be considered a potential economic disadvantage for the mass production of cutting-edge optical devices, particularly diffraction gratings. Therefore, there is a need for an advanced and cost-effective solution for fabricating optical gratings where gap filling does not require CMP (see...). Figure 6 ).

[0007] Therefore, there is a need to allow for more cost-effective production technologies with lower ownership costs. Summary of the Invention

[0008] The inventors have recently discovered that one or more significant problems still require improvement, as described below: Provided are printable formulations for preparing optical layers / composite materials containing a material that provides a sufficiently high refractive index after curing; provided are formulations for manufacturing optical layers that enable the preparation of dense, less cracked or crack-free optical layers and the filling of voids, grooves or gaps after curing. Provides formulations for preparing optical layers comprising metal oxide precursor materials containing high refractive index materials, wherein the high refractive index materials are sufficiently dispersed in the formulation; simpler and / or cost-effective methods for preparing optical layers / composite materials using the formulations; achieving more stable formulations with zero or reduced viscosity changes; and providing suitable formulations for wet printing, i.e. for spin coating or inkjet printing, thereby enabling continuous inkjet printing.

[0009] The inventors aimed to solve one or more of the problems mentioned above.

[0010] Then, the inventors of this application were surprised to find that one or more of the above-mentioned technical problems could be solved by the features defined in the claims.

[0011] That is, a novel formulation has been discovered for preparing optical layers containing metal oxides, preferably for preparing composite materials, more preferably for preparing layered composite materials, wherein the formulation comprises at least: - A metal oxide precursor containing elements of Group 4 and / or Group 5 of the periodic table, preferably a metal alkoxide, metal halide or metal carboxylate containing elements of Group 4 and / or Group 5 of the periodic table, more preferably a metal alkoxide containing elements of Group 4 and / or Group 5 of the periodic table. - An optional acid, said acid being selected from one or more members of sulfonic acids, amine hydrochlorides, and carboxylic acids; and - A solvent, wherein the solvent is a secondary alcohol having one or two alkoxy groups or one or two alkyl groups, wherein one or more non-adjacent groups of the alkyl group are replaced by an oxygen atom; or a secondary alcohol of ≥C3 with a straight chain or branched chain, preferably selected from one or more members of 2-propanol, 2-butanol, 2-pentanol and 3-pentanol, preferably a secondary alcohol of ≥C4 with a straight chain or branched chain; preferably the solvent is selected from propylene glycol monoalkyl ether, glycerol 1,3-dialkyl ether, glycerol 1,3-dialkyl ether or a combination of propylene glycol monoalkyl ether, glycerol 1,3-dialkyl ether and glycerol 1,3-dialkyl ether; - Wherein, based on the total amount of the formulation, the total amount of the metal oxide precursor in the formulation is in the range of 0.1 wt% to 40 wt%, preferably in the range of 1 wt% to 35 wt%, more preferably in the range of 2 wt% to 30 wt%, and even more preferably in the range of 3 wt% to 28 wt%.

[0012] In another aspect, the present invention also relates to a method for preparing the formulation of the present invention, the method comprising at least the following steps: (X1) The metal oxide precursor is dissolved in solvent 1 to form a metal oxide precursor solution, preferably the solvent 1 is a dry or anhydrous solvent; (X2) Optionally, the acid is dissolved in solvent 2 to form an acid solution, preferably the solvent 2 is dry or anhydrous, wherein the acid is selected from one or more members of sulfonic acid, amine hydrochloride and carboxylic acid; (X3) Optionally, the acid solution obtained in step (X2) is added to the metal oxide precursor solution obtained in step (X1); (X4) Mix water and solvent 3 to form an aqueous solvent; and (X5) Add the aqueous solvent to the alkoxide solution obtained in step (X1) or the metal oxide precursor solution obtained in step (X3); (X6) Optionally, the acid and water are dissolved in solvent 4 to form an acid solution to form an aqueous acid solution, preferably the solvent 4 is a dry or anhydrous solvent, wherein the acid is selected from one or more members of sulfonic acid, amine hydrochloride and carboxylic acid; (X7) Optionally, the aqueous acid solution (X6) is added to the metal oxide precursor solution (X1). The solvents 1 to 4 are independently selected from one or more members of the following: propylene glycol monoalkyl ethers, preferably propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether and / or propylene glycol monopropyl ether; glycerol 1,3-dialkyl ether, 1,3-dimethoxy-2-propanol; a linear or branched secondary alcohol of ≥C3, preferably selected from 2-propanol, 2-butanol, 2-pentanol, 3-pentanol, more preferably a linear or branched secondary alcohol of ≥C4; preferably the solvent is selected from propylene glycol monoalkyl ether, glycerol 1,3-dialkyl ether, glycerol 1,3-dialkyl ether.

[0013] In another aspect, the present invention also relates to the use of the formulation of the present invention for preparing optical layers containing metal oxides, preferably for preparing composite materials, and more preferably for preparing layered composite materials.

[0014] In another aspect, the present invention also relates to a method for preparing a composite material containing a metal oxide, preferably the metal oxide being selected from metal monooxides, metal dioxides, and metal pentoxides, or combinations thereof; the method comprising the steps (a) and (b): (a) The formulation of the present invention is preferably provided to the surface of a substrate by a wet deposition method, more preferably by spin coating or zone-selective printing, preferably by inkjet printing, and even more preferably by inkjet printing; and (b) Applying heat treatment to the formulation provided on the surface of the substrate to convert at least a portion of the metal oxide precursor of the formulation into a metal oxide.

[0015] Preferably, the composite material is a layered composite material, and more preferably, the layered composite material is an optical layer.

[0016] In another aspect, the present invention also relates to composite materials obtained or obtainable by the method of the present invention, wherein the composite material is preferably a layered composite material, and more preferably the layered composite material is an optical layer.

[0017] In another aspect, the present invention also relates to a composite material derived from the formulation of the present invention, wherein the composite material is preferably a layered composite material, and more preferably the layered composite material is an optical layer.

[0018] In another aspect, the present invention also relates to an optical device comprising: the composite material of the present invention, and a substrate comprising a patterned surface or an uneven surface. Preferably, the gaps or grooves of the patterned surface or the uneven surface of the substrate are at least partially filled with the composite material.

[0019] Preferably, the substrate is a patterned substrate having morphological features on its surface. Preferably, the composite material fills at least a portion of the gaps in the morphological features; more preferably, the composite material fills the grooves in the patterned substrate.

[0020] In another aspect, the present invention also relates to a display device comprising: at least one functional medium configured to guide and modulate light or configured to emit light; and the composite material of the present invention.

[0021] Technical effects of the present invention

[0022] This invention provides one or more of the following effects: Provided are printable formulations for preparing optical layers / composite materials containing materials that provide a sufficiently high refractive index after curing; provided are formulations capable of preparing dense, less cracked or crack-free optical layers, enabling defect-free filling of voids, grooves or gaps after curing; Provides formulations for preparing optical layers comprising metal oxide precursor materials containing high refractive index materials, wherein the high refractive index materials are sufficiently dispersed in the formulation; provides a simpler and / or more cost-effective method for preparing optical layers / composite materials using the formulations; achieves more stable formulations with zero or reduced viscosity changes; provides suitable formulations for wet printing, i.e. for spin coating or inkjet printing, thereby enabling continuous inkjet printing.

[0023] Preferred embodiments of the invention are described below and in the dependent claims. Attached Figure Description

[0024] Figure 1 : A schematic cross-sectional view of a VPH grating with material 01 and material 02, wherein the difference between the refractive index IR 01 of material 01 and the refractive index IR 02 of material 02 is increasing.

[0025] Figure 2 : A schematic cross-sectional view of a VPH grating capable of optical diffraction (transmission case), including the propagation of diffracted light within a waveguide (e.g., a mirror) via total internal reflection.

[0026] Figure 3A schematic cross-sectional view of a VPH grating with gaps (grooves) to be filled with a high-refractive-index material (material 02), wherein the difference between the refractive index of material 02 and the refractive index of material 01 on the side of the gap (groove) is increasing.

[0027] Figure 4 : Schematic diagram of PVD or CVD-mediated gap filling process and removal of unwanted capping layers.

[0028] Figure 5 : A schematic diagram illustrating how PVD or CVD-mediated gap-filling processes create and leave voids within gaps and deposited layers.

[0029] Figure 6 : A schematic diagram of a gap-filling process using a formulation containing the metal complex of the present invention or a formulation converted into a metal oxide thereof.

[0030] Figure 7a The image shows a TEM image of the Zr-2 sample.

[0031] Figure 7b The image shows a TEM image of the Zr-3 sample.

[0032] List of reference numerals

[0033] 1. Materials with RI 02

[0034] 2. Materials with RI 01

[0035] 3. Substrate (e.g., glass)

[0036] 4. Diffraction of incident light, indicated by the broad arrow.

[0037] 5. Total internal reflection (TIR) ​​of light

[0038] 6. Waveguide

[0039] 7. Structured laminates with gaps (grooves)

[0040] 8. Substrate (e.g., glass or silicon)

[0041] 9. Coatings of materials (e.g., high refractive index materials or highly etch-resistant materials)

[0042] 10. Provide gap-filling materials (e.g., high refractive index materials or highly etch-resistant materials).

[0043] 11. Gaps

[0044] 12. Formulations of high refractive index materials (e.g., metal oxide precursors) (e.g., inks)

[0045] 13. Provide high refractive index materials (e.g., metal oxides) with optional concave geometry for gap filling.

[0046] 14. Overlay (Optional)

[0047] 15. Energy

[0048] Definition of terminology

[0049] In the context of this invention, the term "formulation medium" or its plural form as used herein refers to one or more compounds that serve as a solvent, suspending agent, carrier, and / or matrix for the metal oxide precursor compound and any other components contained in the formulation. Formulation media are generally inert compounds that do not react with the metal oxide precursor compound and the other components. Formulation media can be liquid compounds, solid compounds, or mixtures thereof. Typically, formulation media are organic compounds.

[0050] As used in this article, the term "surfactant" refers to an additive that reduces the surface tension of a given formulation.

[0051] As used herein, the term "wetting and dispersing agent" refers to an additive that enhances the dispersing and filling properties of a given formulation. In this way, the tendency of molecules to adhere to each other is reduced.

[0052] As used in this article, the term "adhesion promoter" refers to an additive that increases the adhesion of a given formulation.

[0053] As used herein, the term "polymer matrix" refers to an additive that serves as a macromolecular matrix for one or more components of a given formulation.

[0054] As used herein, the term "optical device" refers to a device containing one or more optical components for forming a light beam, including but not limited to gratings, lenses, prisms, mirrors, optical windows, filters, polarizing optics, UV and IR optics, waveguides, and optical coatings. In the context of this invention, preferred optical devices are waveguides for augmented reality (AR) devices, virtual reality (VR) devices, and / or mixed reality (MR) devices, or preferably, augmented reality (AR) glasses, virtual reality (VR) glasses, and / or mixed reality (MR) glasses.

[0055] As used herein, the term "display device" is an optical device configured to output / present information in a visual or tactile form. Examples include liquid crystal displays (LCDs), light-emitting diode displays (LED displays), organic light-emitting displays (OLEDs), micro-LED displays, quantum dot displays (QLEDs), AR displays, VR displays, MR displays, plasma display panels (PDPs), and electroluminescent displays (ELDs). Preferred optical devices in the context of this invention are AR displays, VR displays, or MR displays. Detailed Implementation

[0056] This invention relates to a formulation for preparing an optical layer containing a metal oxide, preferably for preparing a composite material, and more preferably for preparing a layered composite material, said formulation comprising at least, substantially, or consisting of the following components: - A metal oxide precursor containing elements of Group 4 and / or Group 5 of the periodic table, preferably a metal alkoxide, metal halide or metal carboxylate containing elements of Group 4 and / or Group 5 of the periodic table, more preferably a metal alkoxide containing elements of Group 4 and / or Group 5 of the periodic table. - An optional acid, said acid being selected from one or more members of sulfonic acids, amine hydrochlorides, and carboxylic acids; and - A solvent, wherein the solvent is a secondary alcohol having one or two alkoxy groups or one or two alkyl groups, wherein one or more non-adjacent groups of the alkyl group are replaced by an oxygen atom; or a straight-chain or branched secondary alcohol with a ≥C3 chain, preferably selected from one or more members of 2-propanol, 2-butanol, 2-pentanol and 3-pentanol, preferably a straight-chain or branched secondary alcohol with a ≥C4 chain; preferably the solvent is selected from propylene glycol monoalkyl ether, glycerol 1,3-dialkyl ether, glycerol 1,3-dialkyl ether or a combination of propylene glycol monoalkyl ether, glycerol 1,3-dialkyl ether and glycerol 1,3-dialkyl ether; - Wherein, based on the total amount of the formulation, the total amount of the metal oxide precursor in the formulation is in the range of 0.1 wt% to 40 wt%, preferably in the range of 1 wt% to 35 wt%, more preferably in the range of 2 wt% to 30 wt%, and even more preferably in the range of 3 wt% to 28 wt%.

[0057] - Metal oxide precursor

[0058] According to the present invention, the metal oxide precursor contains elements of Group 4 and / or Group 5 of the periodic table, preferably the metal oxide precursor is a metal alkoxide, metal halide or metal carboxylate containing elements of Group 4 and / or Group 5 of the periodic table, more preferably the metal oxide precursor is a metal alkoxide containing elements of Group 4 and / or Group 5 of the periodic table.

[0059] Any known metal oxide precursor can be used as a metal oxide precursor.

[0060] -Metal alkoxides

[0061] According to the present invention, a metal alkoxide containing elements of Group 4 and / or Group 5 of the periodic table is used. As said metal alkoxide, a commercially available metal alkoxide containing elements of Group 4 and / or Group 5 of the periodic table can be used.

[0062] Preferably, tetra-n-butoxide titanium, tetra-n-butoxide zirconium, or pentaethanol niobium can be used.

[0063] In a preferred embodiment of the invention, the metal oxide precursor (preferably a metal alkoxide) is represented by the following chemical formula (IV) or formula (V): M b1 O(R b1 R b2 R b3 R b4 )4 -(IV) M b2 O(R b1 R b2 R b3 R b4 R b5 )5 -(V) Where M b1 It is a tetravalent metal of Group 4 elements in the periodic table, preferably Ti or Zr; M b2 It is a pentavalent metal of Group 5 elements in the periodic table, preferably Nb or Ta; R b1 R b2 R b3 R b4 and R b5 Each of the following is independently selected from H and D, and comprises: a straight-chain alkyl group having 1 to 25 carbon atoms, preferably 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms; a branched or cyclic alkyl group having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; an aryl group having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; a straight-chain alkyl-cycloalkyl group having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; a branched alkyl-cycloalkyl group having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms; a straight-chain alkyl-aryl group having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; and a branched alkyl-aryl group having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms. One or more non-adjacent CH2 groups and / or one or more adjacent CH2 groups of the above groups may be replaced by oxygen atoms, and one or more H atoms may be replaced by D or NO2. Each group can be represented by one or more groups R. a replace; R a Each occurrence may be identical or different and may be H, D, a straight-chain alkyl or alkoxy group having 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms; a branched or cyclic alkyl or alkoxy group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; a straight-chain alkenyl or alkynyl group having 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms; a branched alkenyl or alkynyl group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; an aromatic or heteroaromatic ring system having 5 to 15 aromatic ring atoms, preferably 5 to 10 aromatic ring atoms; wherein in each of the above groups, one or more H atoms may be replaced by D, and wherein two or more adjacent substituents R a Here, they can optionally form monocyclic or polycyclic aliphatic ring systems.

[0064] According to the present invention, based on the total amount of the formulation, the total amount of the metal oxide precursor in the formulation is in the range of 0.1% by weight to 40% by weight, preferably in the range of 1% by weight to 35% by weight, more preferably in the range of 2% by weight to 30% by weight, and even more preferably in the range of 3% by weight to 28% by weight.

[0065] It is believed that the aforementioned total amount of the metal oxide precursor, based on the total amount of the formulation, is crucial for achieving improved gap filling or manufacturing thin layers placed directly on patterned surfaces or directly on uneven surfaces of the substrate / underlying layer. When manufacturing thin layers directly onto the patterned or uneven surface of the substrate or the patterned or uneven surface of the underlying layer, it is desirable to fill the bumps, grooves, and recesses of the patterned surface and / or uneven structure with air, and to place the thin layer to cover the air-filled patterned bumps, grooves, and recesses. It is believed that by adjusting the total amount of the metal oxide precursor in the formulation, improved gap filling or good thin layers can be preferably prepared. That is, for improved gap filling (filling the gaps in grooves, bumps, and recesses) of patterned surfaces and uneven structures, a lower amount of metal oxide precursor is desired to achieve a lower condensation rate. Based on the total amount of the formulation, the preferred amount of the metal oxide precursor for achieving improved gap filling is, for example, in the range of 0.1% to 15% by weight, more preferably, in the range of 1% to 10% by weight, and even more preferably in the range of 2% to 8% by weight.

[0066] According to the present invention, based on the total amount of composite materials, the nominal relative weight content of metal oxides in the formulation of the present invention is theoretically in the range of 0.1 wt% to 15 wt%, preferably in the range of 0.2 wt% to 10 wt%, more preferably in the range of 0.5 wt% to 5 wt%, and even more preferably in the range of 0.7 wt% to 4 wt%.

[0067] According to the present invention, the nominal relative weight content of the metal oxide in the formulation is calculated using the following formula: M(OR) in the total dosage form x and MO x (w%) = the general formula (MO2 and M2O5) of metal alkoxides and metal oxides in the formulation (sol-gel mixture) and their nominal relative weight content.

[0068] -solvent

[0069] According to the present invention, the formulation of the present invention contains a solvent, wherein the solvent is a secondary alcohol having one or two alkoxy groups or one or two alkyl groups, wherein one or more non-adjacent groups of the alkyl group are replaced by oxygen atoms.

[0070] It is believed that the secondary alcohol solvent chemically interacts with the metal oxide precursor in the formulation and allows control over the formation rate of the continuous metal oxide material during formulation deposition and final thermal curing processes.

[0071] Preferably, the alkoxy group of the secondary alcohol is an alkoxy group having 1-10 carbon atoms, more preferably it is an alkoxy group having 1-5 carbon atoms, and even more preferably it is an alkoxy group having 1-3 carbon atoms.

[0072] Preferably, the alkyl group in which one or more non-adjacent groups of the alkyl group are replaced by oxygen atoms is an alkyl group having 1-10 carbon atoms, wherein one or more non-adjacent carbon groups of the alkyl group are replaced by oxygen atoms, more preferably having 2-5 carbon atoms, and even more preferably having 2 or 3 carbon atoms.

[0073] Furthermore, the solvent is preferably selected from one or more members of the following: propylene glycol monoalkyl ether, preferably propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether and / or propylene glycol monopropyl ether; glycerol 1,3-dialkyl ether, 1,3-dimethoxy-2-propanol, more preferably the solvent is selected from propylene glycol monoalkyl ether, glycerol 1,3-dialkyl ether, straight-chain or branched ≥C3 secondary alcohols, preferably selected from 2-propanol, 2-butanol, 2-pentanol, 3-pentanol, more preferably straight-chain or branched ≥C4 secondary alcohols; preferably the solvent is selected from propylene glycol monoalkyl ether, glycerol 1,3-dialkyl ether, glycerol 1,3-dialkyl ether.

[0074] It is believed that printing structures, especially inkjet printing, is considered a cost-effective production step. Spin coating is a convenient method and is preferably used to form uniform thin layers. Therefore, suitable solvents for spin-coating / inkjet printing of structures or filling voids and structures are described herein.

[0075] It is believed that selecting chemically closely related secondary alcohols as solvents for reactive sol-gel mixtures containing Group 4 and / or Group 5 elements of the periodic table formed from metal alkoxides allows for control of the formation rate of continuous metal oxide materials during formulation deposition and final thermal curing.

[0076] After printing, depositing, and filling the structure, at least a portion of the material, as a precursor of a metal oxide, needs to be converted into the corresponding metal oxide by any known means (thermal, photochemical, etc.) known to those skilled in the art.

[0077] -acid

[0078] According to the present invention, the formulation may optionally contain an acid selected from one or more members of sulfonic acids, amine hydrochlorides, and carboxylic acids. It is believed that the acid can be used as a reaction medium.

[0079] In a preferred embodiment of the present invention, the formulation of the present invention contains an acid selected from one or more members of sulfonic acids, amine hydrochlorides, and carboxylic acids.

[0080] These acids are believed to be suitable as reaction media according to the present invention.

[0081] In a more preferred embodiment of the invention, the sulfonic acid is represented by the following chemical formula (I): R a1 SO3H -(I) in R a1The group is selected from straight-chain alkyl groups having 1 to 25 carbon atoms, preferably 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms; branched or cyclic alkyl groups having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; aryl groups having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; straight-chain alkyl-cycloalkyl groups having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; branched alkyl-cycloalkyl groups having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms; straight-chain alkyl-aryl groups having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; and branched alkyl-aryl groups having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms. One or more non-adjacent CH2 groups of the above groups may be replaced by oxygen atoms, C=O, C=S, C=Se, C=NH, SiH2, SO, SO2, OS or CONH, and one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2; Each group can be represented by one or more groups R. ax replace; R ax Each occurrence may be identical or different and may be H, D; a straight-chain alkyl or alkoxy group having 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms; a branched or cyclic alkyl or alkoxy group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; a straight-chain alkenyl or alkynyl group having 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms; a branched alkenyl or alkynyl group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; an aromatic or heteroaromatic ring system having 5 to 15 aromatic ring atoms, preferably 5 to 10 aromatic ring atoms; wherein in each of the above groups, one or more H atoms may be replaced by D, F, Cl, Br, I, and wherein two or more adjacent substituents R ax Here, they can optionally form monocyclic or polycyclic aliphatic ring systems with each other; The amine hydrochloride is represented by the following chemical formula (II): HCl·R a2 -(II) in R a2 Selected from N2H4, ammonia, hydroxylamine, imidazole and 1,4-diazabicyclo[2.2.2]octane; and / or The carboxylic acid is represented by the following chemical formula (III): R a3 -COOH in R a3 The group is selected from straight-chain alkyl groups having 1 to 25 carbon atoms, preferably 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms; branched or cyclic alkyl groups having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; aryl groups having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; straight-chain alkyl-cycloalkyl groups having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; branched alkyl-cycloalkyl groups having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms; straight-chain alkyl-aryl groups having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; and branched alkyl-aryl groups having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms. One or more non-adjacent CH2 groups of the above groups may be replaced by oxygen atoms, C=O, C=S, C=Se, C=NH, SiH2, SO, SO2, OS or CONH, and one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2; Each group can be represented by one or more groups R. ax replace; R ax Each occurrence may be identical or different and may be H, D; a straight-chain alkyl or alkoxy group having 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms; a branched or cyclic alkyl or alkoxy group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; a straight-chain alkenyl or alkynyl group having 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms; a branched alkenyl or alkynyl group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; an aromatic or heteroaromatic ring system having 5 to 15 aromatic ring atoms, preferably 5 to 10 aromatic ring atoms; wherein in each of the above groups, one or more H atoms may be replaced by D, F, Cl, Br, I, and wherein two or more adjacent substituents R ax Here, they can optionally form monocyclic or polycyclic aliphatic ring systems.

[0082] In some preferred embodiments, the acid is an amine hydrochloride represented by the following chemical formula (II): HCl·R a2 -(II) in R a2 Selected from N2H4, ammonia, hydroxylamine, imidazole and 1,4-diazabicyclo[2.2.2]octane.

[0083] In a preferred embodiment, the acid is a sulfonic acid represented by the following chemical formula (I): R a1 SO3H -(I) in R a1 The group is selected from straight-chain alkyl groups having 1 to 25 carbon atoms, preferably 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms; branched or cyclic alkyl groups having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; aryl groups having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; straight-chain alkyl-cycloalkyl groups having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; branched alkyl-cycloalkyl groups having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms; straight-chain alkyl-aryl groups having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; and branched alkyl-aryl groups having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms. One or more non-adjacent CH2 groups of the above groups may be replaced by oxygen atoms, C=O, C=S, C=Se, C=NH, SiH2, SO, SO2, OS or CONH, and one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2; Each group can be represented by one or more groups R. ax replace; R ax Each occurrence may be identical or different and may be H, D; a straight-chain alkyl or alkoxy group having 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms; a branched or cyclic alkyl or alkoxy group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; a straight-chain alkenyl or alkynyl group having 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms; a branched alkenyl or alkynyl group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; an aromatic or heteroaromatic ring system having 5 to 15 aromatic ring atoms, preferably 5 to 10 aromatic ring atoms; wherein in each of the above groups, one or more H atoms may be replaced by D, F, Cl, Br, I, and wherein two or more adjacent substituents R ax Here, they can optionally form monocyclic or polycyclic aliphatic ring systems.

[0084] In a preferred embodiment of the invention, the stoichiometric molar ratio of acid to metal oxide precursor, preferably metal alkoxide, is in the range of 0.01:100 to 120:100, and preferably, based on the total amount of metal oxide precursor, the relative molar amount of acid is in the range of 0.1 to 50, more preferably in the range of 1 to 10.

[0085] It is believed that when the stoichiometric molar ratio of the acid and the metal oxide precursor is within the above range, it improves film stability, improves gap-filling properties, and / or provides an improved refractive index value.

[0086] -water

[0087] According to the present invention, the formulation comprises water, and the stoichiometric amount of water is in the range of 100 mol% to 400 mol% based on the total amount of the metal oxide precursor, preferably in the range of 150 mol% to 300 mol% based on the total amount of the metal oxide precursor, and even more preferably in the range of 180 mol% to 270 mol%.

[0088] -additive

[0089] In some embodiments of the invention, the formulation may optionally comprise one or more additives selected from surfactants, wetting and dispersing agents, adhesion promoters, and polymer matrices. Alternatively, in some embodiments, the formulation of the invention does not contain any additives.

[0090] In some embodiments of the invention, the formulation may further comprise one or more additional metal complexes, which may act as additional metal oxide precursors.

[0091] Preferably, based on the total mass of the formulation, the total content of the metal oxide precursor contained in the formulation is in the range of 0.1% to 50% (w / w), more preferably 0.5% to 40% (w / w), and even more preferably 1% to 30% (w / w).

[0092] In a preferred embodiment of the invention, the formulation is an ink formulation suitable for inkjet printing. Typical requirements for ink formulations are a surface tension in the range of 20 mN / m to 30 mN / m and a viscosity in the range of 5 mPa·s to 30 mPa·s.

[0093] -Preparation methods

[0094] In another aspect, the present invention also relates to a method for preparing the formulation of the present invention, said method comprising at least the following steps, substantially consisting of the following steps, or consisting of the following steps: (X1) The metal oxide precursor is dissolved in solvent 1 to form a metal oxide precursor solution, preferably the solvent 1 is dry or anhydrous; (X2) Optionally, the acid is dissolved in solvent 2 to form an acid solution, preferably the solvent 2 is dry or anhydrous, wherein the acid is selected from one or more members of sulfonic acid, amine hydrochloride and carboxylic acid; (X3) Optionally, the acid solution obtained in step (X2) is added to the metal oxide precursor solution obtained in step (X1); (X4) Mix water and solvent 3 to form an aqueous solvent; and (X5) Add the aqueous solvent obtained in step (X4) to the alkoxide solution obtained in step (X1) or the metal oxide precursor solution obtained in step (X3); (X6) Optionally, the acid and water are dissolved in solvent 4 to form an acid solution, to form an aqueous acid solution, preferably the solvent 4 is dry or anhydrous, wherein the acid is selected from one or more members of sulfonic acid, amine hydrochloride and carboxylic acid; (X7) Optionally, the aqueous acid solution (X6) is added to the metal oxide precursor solution (X1). The solvents 1 to 4 are independently selected from one or more members of the following: propylene glycol monoalkyl ethers, preferably propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, and / or propylene glycol monopropyl ether; glycerol 1,3-dialkyl ether, 1,3-dimethoxy-2-propanol, more preferably the solvent is selected from propylene glycol monoalkyl ether, glycerol 1,3-dialkyl ether, glycerol 1,3-dialkyl ether; a straight-chain or branched ≥C3 secondary alcohol, preferably selected from 2-propanol, 2-butanol, 2-pentanol, 3-pentanol, more preferably a straight-chain or branched ≥C4 secondary alcohol; preferably the solvent is selected from propylene glycol monoalkyl ether, glycerol 1,3-dialkyl ether, glycerol 1,3-dialkyl ether.

[0095] Preferably, based on the total amount of the obtained formulation, the total amount of the metal oxide precursor added in step (X1) is set in the range of 0.1 wt% to 40 wt%, preferably in the range of 1 wt% to 35 wt%, more preferably in the range of 2 wt% to 30 wt%, and even more preferably in the range of 3 wt% to 28 wt%.

[0096] Preferably, the metal oxide precursor is a metal alkoxide, metal halide, or metal carboxylate containing elements of Group 4 and / or Group 5 of the periodic table; more preferably, the metal oxide precursor is a metal alkoxide containing elements of Group 4 and / or Group 5 of the periodic table.

[0097] -use

[0098] In another aspect, the present invention also relates to the use of the formulations of the present invention for preparing optical layers containing metal oxides, preferably for preparing composite materials, and more preferably for preparing layered composite materials. The present invention may also relate to the use of the formulations of the present invention for preparing encapsulation layers for electronic devices.

[0099] - Methods for preparing composite materials containing metal oxides

[0100] In another aspect, the present invention also relates to a method for preparing a composite material containing a metal oxide, preferably the metal oxide being selected from metal monooxides, metal dioxides, or metal pentoxides, or combinations thereof; the method comprising at least the steps (a) and (b): (a) The formulation of the present invention is preferably provided to the surface of a substrate or to the surface of a sublayer placed on the substrate by a wet deposition method, more preferably by spin coating or inkjet printing, and even more preferably by inkjet printing; and (b) Apply heat treatment to the formulation provided on the surface of the substrate or on the surface of the bottom layer placed on the substrate to convert at least a portion of the metal oxide precursor of the formulation into a metal oxide.

[0101] Preferably, the composite material is a layered composite material, and more preferably, the layered composite material is an optical layer or an encapsulation layer.

[0102] -Step (a)

[0103] According to the present invention, the formulation can preferably be provided to the surface of a substrate or the surface of a sublayer by a wet deposition method. The wet deposition method is droplet casting, coating, or printing. More preferred coating methods are spin coating, spray coating, slot coating, or slot die coating. More preferred printing methods are flexographic printing, gravure printing, inkjet printing, EHD printing, offset printing, or screen printing. Furthermore, preferred printing methods are spray coating and inkjet printing, with inkjet printing being the most preferred method.

[0104] Therefore, in a preferred embodiment, the formulation is applied to the surface of the substrate or the surface of the sublayer in step (a) by spin coating or inkjet printing. From a cost-effectiveness point of view, inkjet printing is preferred.

[0105] In a preferred embodiment of the invention, the formulation provided in step (a) of the method is an ink formulation suitable for inkjet printing. Typical requirements for ink formulations are a surface tension in the range of 20 mN / m to 30 mN / m and a viscosity in the range of 5 mPa·s to 30 mPa·s.

[0106] Depending on the specific problem to be solved, the formulation may need to be deposited by a coating method as a homogeneous, dense thin layer covering the entire surface of a substrate or the entire underlayer, or the formulation may need to be deposited locally in a structured manner, thus requiring a printing method. Both coating and printing methods require the formulation to be formulated appropriately to meet the physicochemical requirements of the respective coating or printing method, as well as the specific requirements of the substrate surface to be coated or printed.

[0107] In a preferred embodiment of the method of the present invention, the surface of the substrate is pretreated by a surface cleaning process. Preferred surface cleaning processes are silicon wafer cleaning processes, such as those described in W. Kern, *The Evolution of SiliconWafer Cleaning Technology*, *J. Electrochem.Soc.*, vol. 137, 6, 1990, 1887-1892, and *New Process Technologies for Microelectronics*, *RCA Review*, 1970, 31, 2, 185-454. These silicon wafer cleaning processes include wet cleaning processes involving cleaning solvents (e.g., isopropanol (IPA)); wet etching processes involving hydrogen peroxide solutions (e.g., piranha solutions, SC1, and SC2), choline solutions, or HF solutions; dry etching processes involving chemical vapor deposition, UV / ozone treatment, or glow discharge techniques (e.g., O2 plasma etching); and mechanical processes involving brush scrubbing, fluid jetting, or ultrasonic techniques (ultrasonic treatment). The surface of the substrate may also be pretreated by salinization or atomic layer deposition (ALD) processes. Surface pretreatment of the substrate is used to adjust the surface's hydrophobicity / hydrophilicity. This improves the adhesion and filling properties of optical metal oxide layers on the substrate surface.

[0108] In a more preferred embodiment, a wet cleaning process involving a cleaning solvent (e.g., isopropanol (IPA)) is combined with one or more of the following: a wet etching process involving a hydrogen peroxide solution (e.g., piranha solution, SC1 and SC2), a choline solution, or an HF solution; a dry etching process involving chemical vapor deposition, UV / ozone treatment, or glow discharge technology (e.g., O2 plasma etching); and a mechanical process involving brush scrubbing, fluid jetting, or ultrasonic technology (ultrasonic treatment).

[0109] In a preferred embodiment, a wet cleaning process involving a cleaning solvent (e.g., isopropanol (IPA)) is combined with a mechanical process involving brush scrubbing, fluid jetting, or ultrasonic technology (ultrasonic treatment) and a wet etching process involving hydrogen peroxide solution (e.g., piranha solution, SC1 and SC2), choline solution, or HF solution.

[0110] Therefore, in a preferred embodiment, in step (a), the formulation is applied to the surface of the substrate or the surface of the sublayer by spin coating or inkjet printing.

[0111] In a preferred embodiment, the formulation is at least partially converted into a composite material on the surface of the substrate or the surface of the sublayer, wherein the composite material contains: a metal oxide, preferably selected from metal monooxides, metal dioxides and / or metal pentoxides; and a metal oxide precursor.

[0112] In a preferred embodiment, the substrate is a patterned substrate having topographic features on its surface. The patterned structure of the substrate may be a bottom layer placed on top of the substrate (e.g., the bottom layer of a semiconductor device).

[0113] -Step (b)

[0114] It is believed that in step (b), the agent is at least partially converted into a metal oxide on the surface of the substrate or the sublayer by heat treatment to form a composite material. The composite material is preferably a layered composite material. And the solvent is typically removed in step (b).

[0115] Preferred heat treatment includes subjecting the patient to high temperatures of 50°C to 600°C, preferably 80°C to 500°C, and more preferably 100°C to 300°C. It is believed that applying higher temperatures, for example, in the range of 100°C to 600°C, preferably 125°C to 450°C, and more preferably 150°C to 250°C, can achieve improved gap filling.

[0116] Preferably, a formulation containing a lower amount of the metal oxide precursor based on the total amount of the formulation in step (a) is used to achieve improved gap filling, for example, the metal oxide precursor being in the range of 0.1 wt% to 15 wt% based on the total amount of the formulation, more preferably in the range of 1 wt% to 10 wt% based on the total amount of the formulation, and even more preferably in the range of 2 wt% to 8 wt%; and a higher temperature is applied in step (b), for example, a temperature in the range of 100°C to 600°C, preferably 125°C to 450°C, more preferably 150°C to 250°C, to achieve improved gap filling.

[0117] The heat treatment method in step (b) is not limited to any specific heat treatment method or time. Depending on the type of substrate and the formulation, those skilled in the art can determine a suitable heat treatment method.

[0118] In some embodiments of the method for preparing an optical metal oxide layer according to the present invention, a pre-baking step may be applied before step (b) and after step (a) to remove the solvent of the formulation. The formulation may also be partially converted into an optical metal oxide layer on the surface of the substrate by pre-baking (soft baking) at a temperature of 40°C to 150°C, preferably 50°C to 120°C, more preferably 60°C to 100°C; then, the baking (hard baking, sintering, or annealing) of step (b) is applied at a temperature of 100°C to 600°C, preferably 125°C to 450°C, more preferably 150°C to 255°C.

[0119] The purpose of pre-baking (soft baking) is to remove volatile and low-boiling-point components, such as volatile and low-boiling-point formulation media or additives, from droplet-cast, coated, or printed films. Pre-baking is preferably performed for a period of 1 minute to 60 minutes. After pre-baking, a substrate-adhesive film layer of a metal oxide precursor or a mixture of metal oxide precursors is obtained. The film may also contain residual formulation media or additives.

[0120] In an alternative preferred embodiment of the method for preparing an optical metal oxide layer according to the present invention, pre-baking is omitted, such that in step (b), the formulation is directly converted into an optical metal oxide layer on the surface of the substrate or the surface of the sublayer.

[0121] The purpose of baking (hard baking, sintering, or annealing) is to transform the metal oxide precursor or metal oxide precursor mixture layer on the substrate into a metal oxide layer. Furthermore, the final properties of the metal oxide layer can be adjusted through baking. Baking is preferably performed for a time ranging from 1 to 60 minutes, more preferably from 2 to 20 minutes, and even more preferably from 3 to 10 minutes.

[0122] The pre-baking and baking (step (b)) can be carried out in an ambient atmosphere or an atmosphere with increased oxygen content in order to decompose unwanted organic components, which can result in lower activation energy when forming composite materials and is believed to improve the physicochemical properties of the resulting layered composite materials.

[0123] In a preferred embodiment of the method of the present invention, a substrate or sublayer is patterned on its surface, the patterning comprising morphological features, and a layered composite material, preferably an optical layer, forms a coating covering the surface of the substrate and filling the morphological features. Thus, the morphological features are filled and leveled by the composition.

[0124] Preferred topographic features include, for example, gaps, grooves, trenches, and through-holes. These features may be uniformly or non-uniformly distributed on the substrate surface. Preferably, they are arranged as an array or grating on the substrate surface. Preferably, the topographic features have different lengths, widths, diameters, and different aspect ratios. Preferably, the topographic features have an aspect ratio of 1:20 to 20:1, more preferably 1:10 to 10:1. The aspect ratio is defined as the ratio of the width of the structure to its height (or depth). From a dimensional viewpoint, the depth of the topographic features is preferably in the range of 10 nm to 10 μm, more preferably 50 nm to 5 μm, and most preferably 100 nm to 1 μm.

[0125] Preferably, the morphological features are tilted at a certain angle, for example, at an angle of 10° to 80°, more preferably 20° to 60°, more preferably 30° to 50°, and most preferably about 40°. These tilted morphological features are also called tilted or notched morphological features.

[0126] It may also be necessary to partially fill the topographic features with an optical metal oxide layer, either completely or to fill them to a certain extent, but without covering the adjacent surfaces of the substrate where there are no topographic features to be filled.

[0127] The substrate is preferably a substrate for optical devices. The substrate is preferably made of inorganic or organic base materials, with inorganic base materials being more preferred. Preferred inorganic base materials contain materials selected from ceramics, glass, fused silica, sapphire, silicon, silicon nitride, quartz, and transparent polymers or resins. The geometry of the substrate is not particularly limited; however, sheets or wafers are preferred.

[0128] In step (a) of the method, the formulation is applied to the surface of a substrate or the surface of a sublayer, wherein the surface may be the surface of the base material of the substrate or the surface of a layer of material different from the base material of the substrate, wherein such a layer has been formed prior to the application of the formulation.

[0129] In this way, different layers can be formed in sequence (stacked layers) on top of each other. These stacked layers can also be structured, where these structures typically have dimensions at the nanoscale, at least in terms of diameter, width, and / or aspect ratio.

[0130] Therefore, in a preferred embodiment, in step (b), the formulation is at least partially converted into a composite material, preferably a layered composite material, on the surface of the substrate by baking at a temperature of 100°C to 600°C, preferably 125°C to 450°C, more preferably 150°C to 250°C.

[0131] In a preferred embodiment of the invention, the heat treatment in step (b) is applied for a period of time ranging from 1 minute to 60 minutes, preferably from 2 minutes to 20 minutes, and more preferably from 3 minutes to 10 minutes.

[0132] In some embodiments, during the heat treatment in step (b), the formulation is at least partially converted into a composite material on the surface of the substrate, wherein the composite material contains: a metal oxide, preferably selected from metal monooxides, metal dioxides and / or metal pentoxides; and a metal alkoxide or metal halide, metal oxohalide or metal carboxylate.

[0133] - Composite materials

[0134] In another aspect, the present invention relates to a composite material obtained or obtainable by the method of the present invention, preferably a layered composite material, and more preferably, the layered composite material is an optical layer.

[0135] In another aspect, the present invention relates to a composite material derived from the formulation of the present invention, preferably a layered composite material, and more preferably, the layered composite material is an optical layer.

[0136] In a preferred embodiment of the invention, the composite material comprises at least a metal oxide derived from a metal oxide precursor of the formulation and a metal oxide precursor as an unconverted portion of the formulation used in step (a) of the method.

[0137] Details of metal oxide precursors were described in the section on metal oxide precursors above.

[0138] -Optical devices

[0139] The present invention also relates to an optical device comprising the composite material of the present invention, which is prepared by using the formulation according to the present invention as described above.

[0140] Preferably, the optical device is a device comprising one or more optical components for forming a light beam, including but not limited to gratings, lenses, prisms, mirrors, optical windows, filters, polarizing optics, UV and IR optics, waveguides, and optical coatings. In the context of this invention, preferred optical devices are waveguides for augmented reality (AR) devices, virtual reality (VR) devices, and / or mixed reality (MR) devices, or preferably, augmented reality (AR) glasses, virtual reality (VR) glasses, and / or mixed reality (MR) glasses.

[0141] - Display devices

[0142] Finally, the present invention relates to a display device comprising at least one functional medium configured to modulate light or to emit light; and the composite material or optical device of the present invention.

[0143] Examples of the display device are selected from liquid crystal displays (LCDs), light-emitting diode displays (LED displays), organic light-emitting displays (OLEDs), micro LED displays, quantum dot displays (QLEDs), augmented reality (AR) hardware, virtual reality (VR) hardware, mixed reality (MR) hardware, plasma display panels (PDPs), and electroluminescent displays (ELDs). The AR, VR, and MR hardware are also referred to as AR, VR, and MR displays. Preferably, the display device is AR hardware, VR hardware, or MR hardware.

[0144] The following examples further illustrate the invention and should not be considered limiting in any way. Those skilled in the art will recognize that various modifications, additions, and substitutions can be made to the invention without departing from the spirit and scope of the invention as defined in the claims.

[0145] Example

[0146] -Analytical and measurement methods

[0147] The layer thickness, refractive index (n), and absorptivity (k) of the metal oxide layer were determined using elliptic polarization. Measurements were taken using an ellipticity meter M2000 from JAWoolam at three different incident angles (65°, 70°, and 75°). The measurement data were analyzed using CompleteEase software from JAWoolam, assuming complete or near-complete transparency above 600 nm wavelength (at 560 nm), and B-spline fitting was applied to obtain the refractive index (n) and absorptivity (k). Optical constants were averaged from three to four measured samples, each providing a different layer thickness, either after soft baking, hard baking, or a combination of soft baking and subsequent hard baking.

[0148] Unless otherwise stated elsewhere, all chemicals used in the synthesis were purchased from Sigma-Aldrich and used without further purification.

[0149] Preparation of formulation

[0150] Precursor used

[0151] Zirconium tetrabutoxide used in working examples 1 to 5; Titanium tetra-n-butoxide used in working examples 6 to 11; Niobium pentaethanol used in working examples 12 to 14 Weigh the stock solution and organic co-solvent into a glass bottle and stir the formulation for 30 minutes before use.

[0152] Working Example 1: Preparation of Formulation Zr-1

[0153] Formulation Zr-1: Zirconium tetrabutoxide with a nominal solid content of 17% by weight.

[0154] Zirconium tetrabutoxide was added to PGME (1-methoxy-2-propanol: dried with molecular sieves) in a two-necked Schlenk flask connected to an inert gas / vacuum line under an argon atmosphere. The solution was stirred at room temperature, and a solution of H₂O and methanesulfonic acid (MSA) in PGME was added dropwise at room temperature to obtain a clear solution, which was then stirred for an additional 60 minutes. Despite variations in the amounts of solvent and starting material, the mass concentration of the metal alkoxide starting material remained constant.

[0155] The weight percentage and molar percentage of each component used to manufacture the formulation Zr-1 are shown in Table 1 of Zr-1.

[0156] Working Examples 2 to 5: Preparation of Formulations Zr-2 to Zr-5a, b

[0157] Formulations Zr-2 to Zr-5a, b were prepared in the same manner as described in Working Example 1, except that the materials (Zr-2 to Zr-5) described in Table 1 and the amounts described therein were used instead of the materials in Working Example 1.

[0158] Working Examples 6 to 11: Preparation of Formulations Ti-1 to Ti-6

[0159] Formulations Ti-1 to Ti-6 were prepared in the same manner as described in Working Example 1, except that the materials (Ti-1 to Ti-6) described in Table 1 and in the amounts described therein were used instead of the materials in Working Example 1.

[0160] Working Examples 12 to 14: Preparation of Formulations Nb-1 to Nb-3

[0161] Formulations Nb-1 to Nb-3 were prepared in the same manner as described in Working Example 1, except that the materials (Nb-1 to Nb-3) described in Table 1 and the amounts described therein were used instead of the materials used in Working Example 1.

[0162] Table 1: Top layer: A continuous layer of metal oxide material formed by trenches 50 to 150 nm wide across the substrate. Interstitial filling: 50 to 150 nm wide trenches in the substrate filled with metal oxide. T / t (°C / minute): Baking temperature / baking time SC / IJP: Spin Coating / Inkjet Printing Working Example 15: Forming Layer Zr-1 samples were prepared using the following method.

[0163] The Zr-1 formulation from Working Example 1 (WE1) was spin-coated onto an O2 plasma-pretreated Si3N4 / Si substrate with 150 nm wide trenches on its surface. The coating was then baked at 200 °C for 5 minutes. The obtained Zr-1 sample was observed by TEM analysis.

[0164] Samples Zr-2, Zr-3, Zr-4, Zr-5a, and Zr-5b were prepared in the same manner as described in Working Example 15 above, except that different conditions were applied as shown in Table 1. Specifically, for sample Zr-3, two samples were prepared (sample Zr-3 (baking temperature 200℃ / 5 min) and sample Zr-3 (baking temperature 300℃ / 5 min)). For sample Zr-4, three samples were prepared (sample Zr-4 (baking temperature 100℃ / 5 min), sample Zr-4 (baking temperature 200℃ / 5 min), and sample Zr-4 (baking temperature 300℃ / 5 min)).

[0165] For sol-gel derived ZrO2, the selectivity of top-layer formation versus interstitial filling can be controlled by three different parameters: a) Curing temperature b) Solvents: PGME vs DM2P c) Nominal ZrO2 solid content of the formulation Typically, reactive structural units contained in ZrO2 sol-gel formulations exhibit a strong preference for top-layer deposition on O2 plasma-pretreated Si3N4 / Si substrates. This behavior is attributed to the high condensation rate of reactive Zr-oxoclusters formed during the controlled hydrolysis of zirconium butoxide (IV) during formulation preparation. When held in diluted form, gelation of acid-stabilized sols containing ≤8 wt% nominal ZrO2 solids is a slow process (days to weeks) under ambient conditions. Spin-coating deposition on O2 plasma-pretreated Si3N4 / Si substrates induces rapid solvent evaporation and condensation of reactive Zr-oxoclusters with surface Si-OH groups, which is believed to result in high local concentrations and thus rapid condensation into the macroscopic network on the substrate surface.

[0166] Consistent with the mechanical picture of rapid formation of macroscopic ZrO2 domains, the effect of curing temperature on the selectivity of gap filling versus topcoat formation was observed only for ZrO2 sols with a nominal solids content <3.7 wt%. The viscoelasticity of the topcoat initially formed from spin-coated 1.3 wt% ZrO2 sol appeared sufficient to induce material flow into the gaps for curing at T ≥200 °C, while the topcoat remained intact at T=100 °C. However, increasing the solids content to ≥3 wt% ZrO2 resulted in less favorable temperature-induced flow from the initial spin-coated topcoat. This description is consistent with the finding of no gap filling for gap widths <100 nm.

[0167] Figure 7a Figures 1 and 2 show the temperature dependence of top-layer formation versus interstitial filling for a ZrO2 solid content obtained from Examples Zr-2 and Zr-3, respectively. That is, Figure 7a A TEM image of the Zr-2 sample is shown, and Figure 7b A TEM image of the Zr-3 sample is shown.

[0168] The overall rate of condensation of reactive Zr-oxo species to form a macroscopic ZrO2 network can be controlled by selecting the solvent. Indications from experimental data suggest that a lower condensation rate is associated with improved interstitial filling, and this rate is influenced by the solvent i) acting as a terminal ligand for the metal sites at the surface of the reactive Zr-oxo clusters, and ii) being pH-responsive. Typically, secondary alcohols are preferred. More specifically, for ZrO2, replacing 1,3-dimethoxy-2-propanol (DM2P) with 1-methoxy-2-propanol (PGME) enables selective filling of interstitials ≥100 nm at curing temperatures T = 100 to 300 °C. However, this positive solvent effect on interstitial filling is only applicable when the nominal ZrO2 solids content is < about 3 wt%, otherwise top-layer formation will dominate.

[0169] Table 2 shows the results of the TEM analysis. It also shows the solvent dependence of top-layer formation vs. gap filling obtained from Examples Zr-2 and Zr-4, respectively.

[0170] Table 2:

[0171] Table 3 shows the nominal ZrO2 solids content dependence for top-layer formation vs. interstitial filling obtained from Examples Zr-5 and Zr-4, respectively.

[0172] Table 3:

[0173] Table 4 provides the relevant optical properties of ZrO2 films with a thickness of <100 nm.

[0174] Table 4. Optical properties of sol-gel derived ZrO2 thin films; ft = film thickness deposited on a planar Si wafer; net abs. = net absorption determined at 460 nm, normalized to a film thickness of 100 nm.

[0175]

[0176] Working Example 16: Forming Layer

[0177] In Working Example 16, for each case, a Si3N4 / Si substrate with O2 plasma pretreatment having a 50 nm wide trench, a Si3N4 / Si substrate with O2 plasma pretreatment having a 100 nm wide trench, and a Si3N4 / Si substrate with O2 plasma pretreatment having a 150 nm wide trench are provided.

[0178] Then, samples Ti-1 (50 nm wide trench), Ti-1 (100 nm wide trench), Ti-1 (150 nm wide trench), Ti-2 (50 nm wide trench), Ti-2 (100 nm wide trench), Ti-2 (150 nm wide trench), Ti-3 (50 nm wide trench), Ti-3 (100 nm wide trench), Ti-3 (150 nm wide trench), Ti-4a (50 nm wide trench), and Ti-4a (100 nm wide trench) were prepared in the same manner as described in Working Example 15 above. Ti-4a (150nm wide trench), Ti-4b (50nm wide trench), Ti-4b (100nm wide trench), Ti-4b (150nm wide trench), Ti-5 (50nm wide trench), Ti-5 (100nm wide trench), Ti-5 (150nm wide trench), Ti-6 (50nm wide trench), Ti-6 (100nm wide trench), Ti-6 (150nm wide trench), the difference lies in the different conditions applied as described in Table 1 (Ti-1, 2, 3, 4a, 4b, 5 and 6).

[0179] For sol-gel derived TiO2, the selectivity of top-layer formation versus interstitial filling can be mainly controlled by two parameters: a) Solvents: PGME vs DM2P b) Nominal TiO2 solid content of the formulation Typically, reactive structural units in TiO2 sol-gel formulations exhibit variable reactivity, allowing TiO2 to deposit either as a top-layer formation or as an interstitial filler. These complementary modes of deposition can be addressed through solvent selection, which controls the condensation rate of reactive Ti-oxoclusters formed from the initial controlled hydrolysis of titanium butoxide (IV). Besides the solvent, the nominal TiO2 solids content is a second parameter affecting the gelation rate of acid-stabilized sols. While 1-methoxy-2-propanol (PGME) allows for the stabilization of reactive TiO2 sols with a nominal solids content of ≤8 wt% under ambient conditions for days to weeks, substitution with 1,3-dimethoxy-2-propanol reduces the sol's shelf life and necessitates reducing the nominal solids content to ≤2.3 wt%.

[0180] Table 5 shows the solvent dependence of top-layer formation vs. gap filling obtained from Examples Ti-5 and Ti-1, respectively.

[0181] Table 5:

[0182] Spin-coating deposition on an O2 plasma-pretreated Si3N4 / Si substrate leads to rapid solvent evaporation and condensation of reactive Ti-oxoclusters with surface Si-OH groups, presumably resulting in high local concentrations that favor the easy condensation of macroscopic networks onto the substrate surface. The effect of the solvent on the condensation rate, reflected in the sol shelf life and the selectivity of TiO2 deposition as a top layer or interstitial filler, is presumably related to the acid-base properties of the Ti-oxoclusters. Compared to PGME, DM2P bound to the surface Ti(IV) sites of Ti-oxoclusters results in a twofold increase in methoxy groups acting as potential but spatially more distant proton acceptors. The net solvent effect is a stabilizing effect of reduced acid components in reactive TiO2 sols, which is further reflected in the lack of DM2P-derived sols for interstitial filling of 50 nm wide trenches.

[0183] Table 6 highlights the effect of nominal solids content on top-layer vs. gap-filling selectivity for 8 wt% TiO2 sol formulations and approximately 1 wt% TiO2 sol. Selective gap-filling was achieved for all gap widths from 1 wt% TiO2 sol, selective top-layer formation was achieved only for the narrowest gaps from 8 wt% sol, and partial filling was found in addition to top-layer deposition for trenches ≥100 nm wide.

[0184] Table 6 shows the dependence of nominal TiO2 solids content on top-layer formation versus gap filling obtained from Examples Ti-3 and Ti-1, respectively.

[0185] Table 6:

[0186] The inherent high refractive index of rutile and other forms of crystalline TiO2 is also reflected in the optical properties of films deposited by reactive TiO2 sol formulations. The relevant data, along with the processing conditions, are collected in Table 7.

[0187] Table 7. Representative optical properties of sol-gel derived TiO2 films; ft = film thickness deposited on a planar Si wafer; net abs = net absorption determined at 460 nm, normalized to a film thickness of 100 nm.

[0188]

[0189] Working Example 17: Forming Layer

[0190] In Working Example 17, Si3N4 / Si substrates with O2 plasma pretreatment having a 50 nm wide trench, Si3N4 / Si substrates with O2 plasma pretreatment having a 100 nm wide trench, and Si3N4 / Si substrates with O2 plasma pretreatment having a 150 nm wide trench are provided for all cases.

[0191] Then, samples Nb-1 (50 nm wide trench), Nb-1 (100 nm wide trench), Nb-1 (150 nm wide trench), Nb-2 (50 nm wide trench), Nb-2 (100 nm wide trench), Nb-2 (150 nm wide trench), Nb-3 (50 nm wide trench), Nb-3 (100 nm wide trench), and Nb-3 (150 nm wide trench) were prepared in the same manner as described in Working Example 15 above, except that different conditions (Nb-1, 2, and 3) were applied for each case as described in Table 1.

[0192] For sol-gel derived Nb2O5, the selectivity of top-layer formation versus interstitial filling can be controlled by two parameters: a) Solvents: PGME vs DM2P b) Nominal Nb2O5 solid content of the formulation The chemical and deposition properties of Nb₂O₅-derived sol formulations are largely consistent with those of TiO₂, except for a more pronounced solvent effect on sol shelf life and top-layer vs. interstitial filling selectivity, and similar ionic radii to 6-coordinated Ti(IV) and Nb(V). At a 5 mol% acid content, DM₂P-derived sols allow only half the nominal Nb₂O₅ solids content (approximately 3 wt%) that can be processed in PGME.

[0193] Table 8 shows the solvent dependence of top-layer formation vs. gap filling obtained from Examples Nb-3 and Nb-1, respectively.

[0194] Table 8:

[0195] Table 9 shows the nominal Nb2O5 solids content dependence of the gap-filling performance obtained from Examples Nb-2 and Nb-1.

[0196]

[0197] Table 10 provides relevant optical data for Nb2O5 sol-derived thin films.

[0198] Table 10. Optical properties of sol-gel derived Nb₂O₅ films on quartz wafers; ft = film thickness; net abs = net absorption determined at 460 nm, normalized to 100 nm film thickness.

[0199] For Nb-4 in the table, a formulation containing a nominal solid content of 12.6% by weight of Nb2O5 (28.8% by weight of pentaethanol niobium as a metal alkoxide) is prepared and used.

Claims

1. A formulation for preparing an optical layer containing a metal oxide, preferably for preparing a composite material, more preferably for preparing a layered composite material, said formulation comprising at least: - A metal oxide precursor containing elements of Group 4 and / or Group 5 of the periodic table, preferably a metal alkoxide, metal halide or metal carboxylate containing elements of Group 4 and / or Group 5 of the periodic table, more preferably a metal alkoxide containing elements of Group 4 and / or Group 5 of the periodic table. - An optional acid, said acid being selected from one or more members of sulfonic acids, amine hydrochlorides, and carboxylic acids; and - A solvent, wherein the solvent is a secondary alcohol without an alkoxy group, having one or two alkoxy groups, or having one or two alkyl groups, wherein one or more non-adjacent groups of the alkyl group are replaced by an oxygen atom, or a straight-chain or branched ≥C3 secondary alcohol, preferably selected from one or more members of 2-propanol, 2-butanol, 2-pentanol, and 3-pentanol, preferably a straight-chain or branched ≥C4 secondary alcohol; preferably the solvent is selected from propylene glycol monoalkyl ether, glycerol 1,3-dialkyl ether, glycerol 1,3-dialkyl ether, or a combination of propylene glycol monoalkyl ether, glycerol 1,3-dialkyl ether, and glycerol 1,3-dialkyl ether; - Wherein, based on the total amount of the formulation, the total amount of the metal oxide precursor in the formulation is in the range of 0.1 wt% to 40 wt%, preferably in the range of 1 to 35 wt%, more preferably in the range of 2 wt% to 30 wt%, and even more preferably in the range of 3 wt% to 28 wt%.

2. The formulation according to claim 1, wherein the metal oxide precursor is represented by the following chemical formula (IV) or formula (V): M b1 O4(R b1 R b2 R b3 R b4 ) -(IV) M b2 O5(R b1 R b2 R b3 R b4 R b5 ) -(V) Where M b1 It is a tetravalent metal of Group 4 elements in the periodic table, preferably Ti or Zr; M b2 It is a pentavalent metal of a group 5 element in the periodic table, preferably Nb or Ta; R b1 R b2 R b3 R b4 and R b5 Each of the following is independently selected from H and D, and comprises: a straight-chain alkyl group having 1 to 25 carbon atoms, preferably 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms; a branched or cyclic alkyl group having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; an aryl group having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; a straight-chain alkyl-cycloalkyl group having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; a branched alkyl-cycloalkyl group having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms; a straight-chain alkyl-aryl group having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; and a branched alkyl-aryl group having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms. One or more non-adjacent CH2 groups and / or one or more adjacent CH2 groups may be replaced by oxygen atoms, and one or more H atoms may be replaced by D, CN or NO2; Each group can be represented by one or more groups R. a replace; R a Each occurrence may be identical or different and may be H, D, a straight-chain alkyl or alkoxy group having 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms; a branched or cyclic alkyl or alkoxy group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; a straight-chain alkenyl or alkynyl group having 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms; a branched alkenyl or alkynyl group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; an aromatic or heteroaromatic ring system having 5 to 15 aromatic ring atoms, preferably 5 to 10 aromatic ring atoms; wherein in each of the above groups, one or more H atoms may be replaced by D, and wherein two or more adjacent substituents R a Here, they can optionally form monocyclic or polycyclic aliphatic ring systems.

3. The formulation according to claim 1 or 2, wherein the formulation contains an acid selected from one or more members selected from sulfonic acids, amine hydrochlorides, and carboxylic acids.

4. The formulation according to any one of the preceding claims, wherein the sulfonic acid is represented by the following chemical formula (I). R a1 SO3H -(I) in R a1 The group is selected from straight-chain alkyl groups having 1 to 25 carbon atoms, preferably 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms; branched or cyclic alkyl groups having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; aryl groups having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; straight-chain alkyl-cycloalkyl groups having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; branched alkyl-cycloalkyl groups having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms; straight-chain alkyl-aryl groups having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; and branched alkyl-aryl groups having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms. One or more non-adjacent CH2 groups of the above groups may be replaced by oxygen atoms, C=O, C=S, C=Se, C=NH, SiH2, SO, SO2, OS or CONH; and one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2; Each group can be represented by one or more groups R. ax replace; R ax Each occurrence may be identical or different and may be H, D; a straight-chain alkyl or alkoxy group having 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms; a branched or cyclic alkyl or alkoxy group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; a straight-chain alkenyl or alkynyl group having 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms; a branched alkenyl or alkynyl group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; an aromatic or heteroaromatic ring system having 5 to 15 aromatic ring atoms, preferably 5 to 10 aromatic ring atoms; wherein in each of the above groups, one or more H atoms may be replaced by D, F, Cl, Br, I, and wherein two or more adjacent substituents R ax Here, they can optionally form monocyclic or polycyclic aliphatic ring systems with each other; The amine hydrochloride is represented by the following chemical formula (II). HCl·R a2 -(II) in R a2 Selected from N2H4, ammonia, hydroxylamine, imidazole and 1,4-diazabicyclo[2.2.2]octane; and / or The carboxylic acid is represented by the following chemical formula (III). R a3 -COOH in R a3 The group is selected from straight-chain alkyl groups having 1 to 25 carbon atoms, preferably 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms; branched or cyclic alkyl groups having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; aryl groups having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; straight-chain alkyl-cycloalkyl groups having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; branched alkyl-cycloalkyl groups having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms; straight-chain alkyl-aryl groups having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; and branched alkyl-aryl groups having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms. One or more non-adjacent CH2 groups of the above groups may be replaced by oxygen atoms, C=O, C=S, C=Se, C=NH, SiH2, SO, SO2, OS or CONH, and one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2; Each group can be represented by one or more groups R. ax replace; R ax Each occurrence may be identical or different and may be H, D; a straight-chain alkyl or alkoxy group having 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms; a branched or cyclic alkyl or alkoxy group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; a straight-chain alkenyl or alkynyl group having 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms; a branched alkenyl or alkynyl group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; an aromatic or heteroaromatic ring system having 5 to 15 aromatic ring atoms, preferably 5 to 10 aromatic ring atoms; wherein in each of the above groups, one or more H atoms may be replaced by D, F, Cl, Br, I, and wherein two or more adjacent substituents R ax Here, they can optionally form monocyclic or polycyclic aliphatic ring systems.

5. The formulation according to any one of the preceding claims, wherein the acid is an amine hydrochloride represented by the following chemical formula (II). HCl·R a2 -(II) in R a2 Selected from N2H4, ammonia, hydroxylamine, imidazole and 1,4-diazabicyclo[2.2.2]octane.

6. The formulation according to any one of claims 1 to 4, wherein the acid is a sulfonic acid represented by the following chemical formula (I): R a1 SO3H -(I) in R a1 The group is selected from straight-chain alkyl groups having 1 to 25 carbon atoms, preferably 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms; branched or cyclic alkyl groups having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; aryl groups having 3 to 25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; straight-chain alkyl-cycloalkyl groups having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; branched alkyl-cycloalkyl groups having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms; straight-chain alkyl-aryl groups having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; and branched alkyl-aryl groups having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms. One or more non-adjacent CH2 groups of the above groups may be replaced by oxygen atoms, C=O, C=S, C=Se, C=NH, SiH2, SO, SO2, OS or CONH, and one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2; Each group can be represented by one or more groups R. ax replace; R ax Each occurrence may be identical or different and may be H, D; a straight-chain alkyl or alkoxy group having 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms; a branched or cyclic alkyl or alkoxy group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; a straight-chain alkenyl or alkynyl group having 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms; a branched alkenyl or alkynyl group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; an aromatic or heteroaromatic ring system having 5 to 15 aromatic ring atoms, preferably 5 to 10 aromatic ring atoms; wherein in each of the above groups, one or more H atoms may be replaced by D, F, Cl, Br, I, and wherein two or more adjacent substituents R ax Here, they can optionally form monocyclic or polycyclic aliphatic ring systems.

7. The formulation according to any one of the preceding claims, wherein the stoichiometric molar ratio of the acid to the metal oxide precursor is in the range of 0.01:100 to 120:100, preferably, the relative molar amount of the acid is in the range of 0.1 to 50, more preferably 1 to 10, based on the total amount of the metal oxide precursor.

8. The formulation according to any one of the preceding claims, wherein the solvent is selected from one or more members of propylene glycol monoalkyl ethers, glycerol 1,3-dialkyl ethers, and 1,3-dimethoxy-2-propanol, preferably the propylene glycol monoalkyl ether is propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether and / or propylene glycol monopropyl ether; more preferably the solvent is selected from propylene glycol monoalkyl ethers, glycerol 1,3-dialkyl ethers or any mixture thereof.

9. The formulation according to any one of the preceding claims, wherein the formulation comprises water, and the stoichiometric amount of water is in the range of 100 mol% to 400 mol% based on the total amount of the metal oxide precursor, preferably in the range of 150 mol% to 300 mol% based on the total amount of the metal oxide precursor, and even more preferably in the range of 180 mol% to 270 mol%.

10. A method for preparing an formulation according to any one of the preceding claims, the method comprising at least the following steps: (X1) The metal oxide precursor is dissolved in solvent 1 to form a metal oxide precursor solution, preferably the solvent 1 is a dry or anhydrous solvent; (X2) Optionally, the acid is dissolved in solvent 2 to form an acid solution, preferably the solvent 2 is a dry or anhydrous solvent, wherein the acid is selected from one or more members of sulfonic acid, hydrochloride and carboxylic acid; (X3) Optionally, the acid solution obtained in step (X2) is added to the metal oxide precursor solution obtained in step (X1); (X4) Mix water and solvent 3 to form an aqueous solvent; and (X5) Add the aqueous solvent to the alkoxide solution obtained in step (X1) or the metal oxide precursor solution obtained in step (X3); (X6) Optionally, the acid and water are dissolved in solvent 4 to form an acid solution to form an aqueous acid solution, preferably the solvent 4 is a dry or anhydrous solvent, wherein the acid is selected from one or more members of sulfonic acid, hydrochloride and carboxylic acid; (X7) Optionally, the aqueous acid solution (X6) is added to the metal oxide precursor solution (X1). The solvents 1 to 4 are independently selected from one or more members of the following: propylene glycol monoalkyl ethers, preferably propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, and / or propylene glycol monopropyl ether; glycerol 1,3-dialkyl ether, 1,3-dimethoxy-2-propanol, more preferably the solvent is selected from propylene glycol monoalkyl ether, glycerol 1,3-dialkyl ether, glycerol 1,3-dialkyl ether; a straight-chain or branched ≥C3 secondary alcohol, preferably selected from 2-propanol, 2-butanol, 2-pentanol, 3-pentanol, more preferably a straight-chain or branched ≥C4 secondary alcohol; preferably the solvent is selected from propylene glycol monoalkyl ether, glycerol 1,3-dialkyl ether, glycerol 1,3-dialkyl ether.

11. A method for preparing a composite material containing a metal oxide, preferably said metal oxide is selected from metal monooxides, metal dioxides, or metal pentoxides, or combinations thereof; said method comprising the steps (a) and (b): (a) Preferably by wet deposition, more preferably by spin coating or zone-selective printing, preferably by inkjet printing, even more preferably by inkjet printing, the formulation according to any one of claims 1 to 9 is provided to the surface of the substrate or the surface of the sublayer; and (b) Applying heat treatment to the formulation provided on the surface of the substrate or the surface of the sublayer to convert at least a portion of the metal oxide precursor of the formulation into a metal oxide; Preferably, the composite material is a layered composite material, and more preferably, the layered composite material is an optical layer.

12. The method according to any one of claims 11, wherein the formulation is at least partially converted into a composite material on the surface of the substrate, wherein the composite material comprises: a metal oxide, preferably selected from metal monooxides, metal dioxides and / or metal pentoxides; and a metal alkoxide, metal halide, metal oxohalide or metal carboxylate.

13. A composite material derived from a formulation according to any one of claims 1 to 9, wherein the composite material is preferably a layered composite material, and more preferably the layered composite material is an optical layer.

14. An optical device comprising: the composite material of claim 13, and a substrate comprising a patterned surface or an uneven surface.

15. A display device comprising at least one functional medium configured to guide and modulate light or configured to emit light, and a composite material according to claim 13 or an optical device according to claim 14.

Images