Formulations for producing optical metal oxide layers

Abstract

The present invention relates to a formulation for preparing an optical metal oxide layer, comprising a polyoxometallate (POM) complexed with metal oxide nanoparticles (NP); a process for preparing an optical metal oxide layer using the formulation; and an optical device comprising the optical metal oxide layer.

Description

Technical Field

[0001] The present invention relates to a formulation for preparing an optical metal oxide layer, the formulation comprising a polyoxometalate (POM) complexed with metal oxide nanoparticles (NPs); a method for preparing an optical metal oxide layer; and an optical device comprising an optical metal oxide layer. The formulation and method according to the present invention are particularly suitable for preparing metal oxide optical layers for optical applications or devices, such as diffraction gratings for augmented reality (AR) and / or virtual reality (VR) devices. The metal oxide layer exhibits (a) favorable optical properties, such as a high refractive index (RI) of >1.7, preferably >2.0 at a wavelength of ≤520 nm and / or a low absorption of <0.1% at 480 nm and / or a low degree of haze formation; (b) favorable mechanical properties, such as low shrinkage; (c) favorable coating properties, such as a dense layer and a flat surface structure; and / or (d) favorable filling properties, such as homogeneous filling of topographical features on patterned substrates.

[0002] Embodiments of the present invention allow for the fabrication of optical metal oxide layers on the surfaces of patterned and unpatterned substrates. The metal oxide layers can be formed into various structures, such as layers covering the surface of unpatterned substrates and / or fillers covering topographical features, such as gaps, on the surface of patterned substrates, thereby providing highly refractive optical structures. In particular, embodiments of the present invention allow for the fabrication of advanced optical gap fillers with low coverage, thereby enabling easy and cost-effective mass production of complex optical devices by avoiding typical problems associated with layer deposition or gap filling using physical vapor deposition (PVD) or chemical vapor deposition (CVD) techniques, such as incomplete or excessive gap filling due to unfavorable deposition and layer growth characteristics, such as reduced or increased deposition or growth rates at corners and edges.

[0003] Embodiments of the present invention are particularly suitable for preparing optical metal oxide layers with high refractive index for optical devices, such as for diffraction gratings in AR and / or VR devices.

[0004] Finally, the present invention provides an optical device, preferably an AR and / or VR device, comprising an optical metal oxide layer obtainable by the process according to the invention or prepared by using a formulation according to the invention. Background Art

[0005] Cutting-edge optical devices often include gratings made of composite materials with a substrate as a support and a complex, interlaced pattern made up of different layers or stacks of layers. Typically, forming such complex, interlaced patterns requires a structuring process, which becomes increasingly challenging as the size of the structures being fabricated decreases.

[0006] In addition to a wide range of possible uses in various application areas, such as in spectrometers or optical storage systems (CDs, DVDs, etc.), diffraction gratings are core components of so-called XR devices (mostly glasses). In this context, R stands for the term reality, and X stands for different attributes, such as virtual, augmented, mixed, etc. Therefore, diffraction gratings form part of the core of the so-called optical engine in XR devices, especially augmented and mixed reality glasses. Virtual reality glasses, when constructed as head-mounted displays, often consist of conventional liquid crystal (LC) or organic light-emitting diode (OLED) displays embedded in the device and therefore do not necessarily require a diffraction grating. In contrast, augmented and mixed reality glasses are designed to enable consumers to obtain a visual impression of their environment, preferably as if they were not wearing any glasses at all. However, these augmented and mixed reality glasses also make it possible to provide and supply digital information and also project it into the individual's field of view. The additional digital information is collected by identifying and analyzing the environment that the individual is monitoring or currently viewing. In order to transmit and project supporting digital information into the individual's eyes, augmented reality or mixed reality glasses are equipped with an information supply unit that is coupled to an optical waveguide system, via which the optically encoded supporting information is transmitted directly to the lenses of the glasses. Here, the information passes through a diffraction grating, which couples the incident light into the lens and splits the incident light by diffraction according to the angular information of the incident light and the spectral band of the incident light. After the light is coupled in, the lens acts as a waveguide capable of transmitting the light to and into the individual's pupil. The position of the light coupling is independent of any preferred position and is therefore not affected by technical requirements. The propagation direction of the light within the lens is determined by diffraction or splitting the light by the diffraction grating. At certain positions in the lens, a second diffraction grating and a third diffraction grating are used to change the propagation direction of the light and thereby force the light to be projected into the user's pupil. Light propagation in the glasses is achieved by total internal reflection (TIR) of light, so the light bounces several times between the glass interfaces until it reaches another diffraction grating, which changes the internal TIR direction of the light (see Figure 2). The second and third gratings are geometrically aligned in different directions relative to the first coupling-in grating (for example, by a certain angular twist of the longitudinal axis), thus allowing to change the propagation direction of the totally internally reflected light. It goes without saying that the lens itself or the material from which the lens is made should not be absorptive. Otherwise, the supporting information never reaches the user's pupil, or only reaches the user's pupil when the light intensity is largely depleted. The process works whether a reflection grating or a transmission grating is used. Usually, the lens is equipped with two types of gratings to guide the light appropriately. It should also be mentioned that there are differences in the optical properties of reflection and transmission gratings, which, however, are not of further concern in the context of the present invention. The basic structure of the gratings is very similar, which is more important at this point.

[0007] However, there are different designs and structures, such as surface relief (SR) or volume phase holographic (VPH) gratings, used to implement waveguides. Both types are very similar in appearance. In the simplest case, the grating is mounted to the surface of a waveguide material (here, a lens) in some way. The grating itself consists of an array of fine structures, primarily, but not limited to, grooves in a first material type, material O1, having a refractive index RI01. The groove geometry can vary, from rectangular grooves to V-shaped grooves, U-shaped grooves, and the like. The width (including structures with different widths), the groove geometry, their spacing, and their depth (including different depths) are specifically designed to influence the diffraction pattern of the incident light to be diffracted.

[0008] In the case of SR gratings (SRGs), trenches or structures of a first material type (Material 01) with a refractive index (RI 01) are filled with a second material type (Material 02) with a refractive index (RI 02) that gradually differs from RI 01 (see Figure 1 and Figure 3 ). For the sake of completeness, it should be mentioned that material O1 or material O2 can be composed of a stack of structured layers each containing different material compositions with different refractive indices, which structured layers are stacked on top of each other, thereby forming material O1 or material O2 with an effective or gradient refractive index RI O1 or RI O2, respectively. Incidentally, the (effective or gradient) refractive indices RI O1 and RI O2 depend on the refractive index of the waveguide or lens of which the glasses are made. If a glass lens with a high refractive index (nO3>1.46) is used, the (effective or gradient) refractive index of material O1 and material O2 is considered to be higher than the refractive index of the lens itself, whereby RI values of 2.0 can be reached and exceeded. High-performance gratings, in particular SR-type gratings, can be manufactured using standard lithography and deposition techniques known from microfabrication, such as the manufacture of integrated circuits.

[0009] Such standard techniques typically include physical vapor deposition (PVD) or chemical vapor deposition (CVD) processes and often suffer from incomplete gap filling due to unfavorable deposition and / or layer growth deposition properties, including increased deposition and / or growth rates at corners and edges. Such incomplete gap filling results in the formation of voids within the structures to be filled by the PVD and CVD materials. In addition to the formation of voids, the surface of the substrate is also covered with a PVD and / or CVD layer that is almost as thick as the maximum depth of the deepest structure to be filled by the deposited gap fill 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, there is a need to remove undesired overlying layers from PVD or CVD, for example by chemical mechanical planarization (CMP), without damaging the underlying original substrate surface. Although CMP is well established in the process of manufacturing integrated circuits, it is a time-consuming and expensive process and can be seen as a potential economic disadvantage for the mass production of leading-edge optical devices, especially diffraction gratings. Therefore, there is a need for an advanced and cost-effective solution for manufacturing gratings, where CMP is not required for gap filling (see Figure 6 ).

[0010] The present invention addresses the various shortcomings of the techniques used to prepare gratings for cutting-edge optical devices described above. The focus here is on improved optical properties, improved mechanical properties, improved coating properties, and improved filling properties.

[0011] Objectives of the present invention

[0012] The object of the present invention is to provide a formulation and a method for preparing an optical metal oxide layer, wherein the metal oxide layer is particularly suitable for optical applications and can be used in optical devices, such as diffraction gratings for AR and / or VR devices. The obtained optical metal oxide layer exhibits (a) favorable optical properties, such as a high refractive index (RI) of >1.7, preferably >2.0 at a wavelength of ≤520 nm, low absorption and low haze formation; (b) favorable mechanical properties, such as low shrinkage; (c) favorable coating properties, such as a dense layer and a flat surface structure; and (d) favorable filling properties, such as homogeneous filling of topographical features on patterned substrates.

[0013] Furthermore, it was an object of the present invention to provide a formulation and a method which allow easy and cost-effective production of optical metal oxide layers.

[0014] Another object of the present invention is to enable the preparation of optical metal oxide layers on the surfaces of patterned or unpatterned substrates. The metal oxide layer can be formed into various structures, such as a layer covering the surface of an unpatterned substrate and / or a filler covering topographical features (such as gaps) on the surface of a patterned substrate, thereby providing highly refractive optical structures.

[0015] It was therefore an object of the present invention to provide a formulation and a method for producing optical metal oxide layers, wherein the method allows the preparation of advanced optical gap fillers with low coverage, thus enabling easy and cost-effective mass production of complex optical devices.

[0016] Another object of the present invention is to provide a method for producing optical metal oxide layers which avoids typical problems arising when layer deposition or gap filling is performed by PVD or CVD techniques, such as incomplete or excessive gap filling due to unfavorable deposition and layer growth characteristics, such as reduced or increased deposition or growth rates at corners and edges.

[0017] The present invention targets metal complexes and formulations that are particularly suitable for producing metal oxide optical layers with high refractive index and at the same time low absorption (light loss) for optical devices, such as diffraction gratings in AR and / or VR devices.

[0018] Finally, it is an object of the present invention to provide an optical device, preferably an AR and / or VR device, comprising an optical metal oxide layer obtainable by the process according to the invention or prepared by using the formulation according to the invention and thereby exhibiting the above-mentioned beneficial effects. Summary of the Invention

[0019] The inventors of the present invention have surprisingly found that the above objects are achieved by a formulation for preparing an optical metal oxide layer, alone or in any combination, wherein the formulation comprises:

[0020] (i) a complex comprising

[0021] a polyoxometalate moiety of formula (Ia), and

[0022] [Q l ] n+ [X z Y p O y ] n- (Ia)

[0023] Nanoparticles of formula (Ib)

[0024] M i M' j M” f Ok (Ib)

[0025] in

[0026] Each Q independently represents a cation, preferably wherein the cation is selected from the group consisting of ammonium cations, alkali metal cations, alkaline earth metal cations,

[0027] l is any number within the range of 1 to 20, preferably 1 to 10;

[0028] n represents the total positive charge n+ of the cation Q and the polyanion [X z Y p O y ] corresponds to the number of negative charges n-;

[0029] X is a heteroatom such as B, Si, Ge, P, Al, As or Sb;

[0030] Y is a metal, preferably a transition metal;

[0031] z is 0 to 20; p is 1 to 100; and y is 2 to 400;

[0032] M, M' and M" are each independently a metal;

[0033] i, j and f are each independently an integer or fraction from 0 to 10; provided that at least one of i, j and f is not 0; and

[0034] k is any number within the range of 1 to 20, preferably 1 to 5;

[0035] and

[0036] (ii) one or more formulation media.

[0037] In addition, a method for preparing an optical metal oxide layer is provided, comprising the following steps (a) to (c):

[0038] (a) providing a formulation, wherein the formulation comprises:

[0039] (i) a complex comprising a polyoxometalate moiety of formula (Ia) and a nanoparticle of formula (Ib); and

[0040] (ii) one or more formulation media; and

[0041] (b) applying the formulation to the surface of a substrate; and

[0042] (c) converting the formulation on the surface of the substrate into an optical metal oxide layer.

[0043] Furthermore, an optical device is provided, comprising an optical metal oxide layer obtainable by or by a method according to the above-described preparation method.

[0044] The present invention further relates to the use of the above-described formulation for forming optical metal oxide layers.

[0045] Preferred embodiments of the invention are described below and in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 : Schematic cross-section of an SR grating having material 01 and material 02, wherein the refractive index IR01 of material 01 gradually differs from the refractive index IR02 of material 02.

[0047] Figure 2 : Schematic cross-sectional view of an SR grating, which implements light diffraction (transmission case) by propagating diffracted light within a waveguide (e.g., a lens) by total internal reflection.

[0048] Figure 3 : A schematic cross-sectional view of an SR grating is provided with a gap (groove) to be filled with a high refractive index material (material 02), wherein the refractive index of material 02 gradually differs from the refractive index of material 01 flanking the gap (groove).

[0049] Figure 4 : Schematic representation of the PVD or CVD mediated gap filling process and removal of undesired overlying layers.

[0050] Figure 5 : Schematic representation of a PVD or CVD mediated gap fill process that creates and leaves voids within the gap and deposited layer.

[0051] Figure 6 : Schematic representation of a gap filling process using a formulation containing the metal complexes of the invention or formulations thereof for conversion to metal oxides.

[0052] Figure 7A and Figure 7B : Shows a comparison of UV-Vis spectra of diluted samples of supernatant solution (A) and lysate (B) obtained using standard and solvent methods.

[0053] Figure 8 : shows the FT-IR spectra of dried samples of the products obtained using purification methods 1 and 2.

[0054] Figure 9 : Shows the reaction mixture containing the product which precipitated over time after addition of 10% (v / v) solvent.

[0055] Figure 10 :Show K8Nb6O19 Pure solution in a mixed solvent system of added solvent, isopropanol and water.

[0056] Figure 11 : Demonstrates the refractive index dependence of PW-TiO2 weight fraction of PW-TiO2 / PW-SnO2 mixtures.

[0057] Figure 12 : Shows the refractive index of the mixtures PW-TiO2 and PW-A as a function of the weight percentage content of PW-TiO2 on films deposited on Si substrates and cured at 300°C.

[0058] Figure 13 : Shows the refractive index of PW-TiO2 and PW-SnO2 mixtures (0.94PW-TiO2 weight fraction) as the weight fraction of added PW-A changes.

[0059] Figure 14 : Shows surface feature filling of a spin-coated 5 wt% PW-SnO2 formulation after soft baking at 100°C for 1 min and hard baking at 300°C for 10 min.

[0060] Figure 15A : Shows surface feature filling of drop-cast H2O containing 10 wt% PW-SnO2 and 0.5 wt% BYK348 after soft baking at 100°C for 1 min and baking at 300°C for 10 min.

[0061] Figure 15B : Shows surface feature filling of a spin-coated H2O containing 10 wt% PW-SnO2 and 0.5 wt% BYK348 after soft baking at 100°C for 1 min and baking at 200°C for 10 min.

[0062] Figure 16 : Shows surface feature filling of a mixture of spin-coated Example T3 (PW-SnO2 / PW at a 1.8 / 1 weight ratio) after soft baking at 100°C for 1 min and hard baking at 300°C for 10 min.

[0063] Figure 17A and Figure 17B Shows spin coating of NbO-Sn mixture after pre-baking at 100℃ for 1min .25 Ti .75 O2+NbO-A surface feature filling. Showing two groove widths: 114nm ( Figure 17A ) and 87.5nm( Figure 17B ).

[0064] Figure 17CThe spin coating of the mixture NbO-Sn was demonstrated after hard baking at 300°C for 10 min followed by soft baking at 100°C for 1 min. .25 Ti .75 Surface feature filling with O2+NbO-A. Demonstrating 84nm trench width.

[0065] Figure 18A and Figure 18B Surface feature filling of spin-coated mixture NbO-SnO2\TiO225 / 75%+NbO after soft baking at 100°C for 1 min and hard baking at 300°C for 10 min is shown. The groove width is 114 nm ( Figure 18A ) and 131nm( Figure 18B ).

[0066] Figure 18C : Shows surface feature filling of spin-coated mixture NbO—SnO 2 \ TiO 2 25 / 75% + NbO—A without any soft bake between two layers and after final soft bake at 100°C for 1 min after the second layer and hard bake at 300°C for 10 min after the soft bake.

[0067] Figure 19A : An exemplary scheme showing POM complexed with nanoparticles.

[0068] Figure 19B : Demonstrates the encapsulation of POM on the surface of NPs, where the radius of the NPs is much larger than that of the POM, to illustrate the calculation of the core radius.

[0069] Reference Symbols List

[0070] 1 Material 02 with RI 02

[0071] 2 Material 01 with RI 01

[0072] 3. Substrate (e.g., glass)

[0073] 4 Diffraction of incident light indicated by broad arrows

[0074] 5 Total Internal Reflection (TIR) of Light

[0075] 6 Waveguide

[0076] 7 Stack of structured layers with gaps (grooves)

[0077] 8 Substrate (e.g., glass or silicon)

[0078] 9 Covering layer of material (e.g., high refractive index material or high etching resistance material)

[0079] 10 Provide gap-filling materials (e.g., high refractive index materials or high etch resistance materials)

[0080] 11 Gap

[0081] 12 Formulations (e.g., inks) of high refractive index materials (e.g., metal oxide precursors)

[0082] 13 Provide a gap-filled high refractive index material (e.g., metal oxide) with optional concave geometry

[0083] 14 Covering layer (optional)

[0084] 15 Energy

[0085] 100 nanoparticles (NPs)

[0086] 102 Polyoxometalates (POM)

[0087] 104 Projection of POM on the NP spherical surface

[0088] 106 Radius R DETAILED DESCRIPTION

[0089] definition

[0090] In the context of the present invention, the term "formulation medium" or the plural term "formulation medium" as used herein refers to one or more compounds that act as a solvent, suspending agent, carrier and / or matrix for the complex and any other components included in the formulation. The formulation medium is generally an inert compound that does not react with the complex and the other components. The formulation medium can be a liquid compound, a solid compound, or a mixture thereof. The preferred formulation medium is water.

[0091] When the numerical range is indicated using "to", it includes both endpoints. For example, 1 to 10 means 1 or more and 10 or less.

[0092] As used herein, the term "surfactant" refers to an additive that reduces the surface tension of a given formulation.

[0093] The term "wetting agents and dispersants" as used herein refers to additives that increase the spreading and penetration properties of a given formulation. In this way, the tendency of molecules to stick to each other is reduced.

[0094] As used herein, the term "tackifier" refers to an additive that increases the adhesion of a given formulation.

[0095] As used herein, the term "coordinating surfactant" refers to an additive that coordinates metal ions and acts as a surfactant.

[0096] As used herein, the term "viscosity enhancer" refers to an additive that increases the viscosity of a given formulation.

[0097] 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, and optical coatings. Preferred optical devices in the context of the present invention are augmented reality (AR) glasses and / or virtual reality (VR) glasses.

[0098] As used herein, the term "metal" includes alkali metals, alkaline earth metals, transition metals, rare earth elements, post-transition metals, actinides, metalloids, and lanthanides.

[0099] As used herein, the term "late transition metal" refers to Al, Ga, In, Sn, Ti, Pb, Bi, Nh, Fl, Mc, and Lv.

[0100] The term "metalloid" as used herein refers to B, Si, Ge, As, Sb, Te and Po.

[0101] As used herein, the cation "Q" may be a proton, an ammonium cation, an alkali metal cation, and an alkaline earth metal cation.

[0102] As used herein, the term "nanoparticle" or "NP" refers generally to any unit having a structure in which at least one dimension is nanoscale (i.e., from 1 nm to 1 μM). The term "nanoparticle" includes quantum dots, spherical and pseudo-spherical particles, polyhedral particles, nanorods, nanowires, tetrahedral pyramids, anisotropic particles, nanosheets, and other suitable particles. In addition, the term "nanoparticle" includes single-crystalline nanoparticles (i.e., nanocrystals), polycrystalline nanoparticles, and amorphous nanoparticles. The nanoparticles referred to herein are represented by formula (Ib):

[0103] M i M' j M” f O k (Ib)

[0104] M, M' and M" are each independently a metal;

[0105] i, j and f are each independently an integer or fraction from 0 to 10; provided that at least one of i, j and f is not 0; and

[0106] k is any number within the range of 1-20, preferably 1-5.

[0107] The polyoxometalates or "POMs" referred to herein are represented by formula (Ia),

[0108] [Ql ] n+ [X z Y p O y ] n- (Ia)

[0109] in

[0110] Each Q independently represents a cation, preferably wherein the cation is selected from the group consisting of ammonium cations, alkali metal cations, alkaline earth metal cations,

[0111] l is any number within the range of 1 to 20, preferably 1 to 10;

[0112] n represents the total positive charge n+ of the cation Q and the polyanion [X z Y p O y ] corresponds to the number of negative charges n-;

[0113] X is a heteroatom such as B, Si, Ge, P, Al, As or Sb;

[0114] Y is a metal, preferably a transition metal; and

[0115] z is 0 to 20; p is 1 to 100; and y is 2 to 400.

[0116] The complexes referred to herein relate to metal oxide nanoparticles complexed with POMs acting as ligands. Figure 15A Schematic diagrams of such complexes comprising a polyoxometalate moiety according to Formula Ia and a nanoparticle according to Formula Ib are shown. In some cases, a single M, M', and M" of the nanoparticle can be considered as part of the polyoxometalate, for example, when the polyoxometalate is a vacant polyoxometalate, Na7[PW complexed with TiO2 11 O 39 The polyoxometalate portion of [PW 11 O 39 Ti]-O - When reference is made herein to POMs complexed with NPs, it is to be understood that the preceding description is also covered.

[0117] The use of POM as a protective ligand complexed with NPs to produce POM-NP separable and water-soluble nanostructures is known from the literature, e.g.

[0118] (1) Y. Wang, I. Weinstock, Chem. Soc. Rev., 2012, 41, 7479-7496.

[0119] (2) M. Raula, G. Gan Or, M. Saganovich, O. Zeiri, Y. Wang, M Chierotti, R. Gobetto, I. Weinstock, Angew. Chem. Int. Ed. 2015, 54, 12416-12421.

[0120] (3) Anna Llordes, Aaron T. Hammack, Raffaella Buonsanti, Ravisubhash Tangirala, Shaul Aloni, Brett A. Helmsa and Delia J. Milliron, J. Mater. Chem., 2011, 21, 11631-11638.

[0121] Preferred Implementation

[0122] Formulations for producing optical metal oxide layers

[0123] In a first aspect, a formulation for preparing an optical metal oxide layer is provided, wherein the formulation comprises:

[0124] (i) a complex comprising a polyoxometalate moiety of formula (Ia), and

[0125] [Q l ] n+ [X z Y p O y ] n- (Ia)

[0126] Nanoparticles represented by formula (Ib)

[0127] M i M' j M” f O k (Ib)

[0128] in

[0129] Each Q independently represents a cation, preferably wherein the cation is selected from the group consisting of ammonium cations, alkali metal cations, alkaline earth metal cations,

[0130] l is any number within the range of 1 to 20, preferably 1 to 10;

[0131] n represents the total positive charge n+ of the cation Q and the polyanion [X z Y p O y ] corresponds to the number of negative charges n-;

[0132] X is a heteroatom such as B, Si, Ge, P, Al, As or Sb;

[0133] Y is a metal, preferably a transition metal;

[0134] z is 0 to 20; p is 1 to 100; and y is 2 to 400;

[0135] M, M' and M" are each independently a metal;

[0136] i, j and f are each independently an integer or fraction from 0 to 10; provided that at least one of i, j and f is not 0; and

[0137] k is any number within the range of 1 to 20, preferably 1 to 5;

[0138] and

[0139] (ii) one or more formulation media.

[0140] Preferably, (Na7[α-PW 11 O 39 ]), Na3[PMo complexed with TiO2 12 O 40 ]、K6[P2W complexed with TiO2 18 O 62 ]、K6[P2Mo complexed with TiO2 18 O 62 ] or Q complexed with TiO2 l [SiW 11 O 39 ], are excluded from the formulation according to the first aspect.

[0141] In some embodiments, the complex is represented by formula (I):

[0142] ([Q l ] n+ [POM] n- ) m (NP) r (I)

[0143] in

[0144] l is any number in the range of 1 to 40;

[0145] POM is a polyoxometalate ligand represented by formula (Ia);

[0146] n is the total positive charge representing Q + and the corresponding negative charge n of the polyoxometalate ligand -, and wherein n may be any number in the range of 2 to 20;

[0147] NP is a nanoparticle represented by formula (Ib);

[0148] m represents the number of polyoxometalate ligands per nanoparticle and is any number in the range of 1 to 5000; and

[0149] r is any number in the range of 1 to 20,000 and represents the empirical metal oxide unit in the nanoparticle.

[0150] In formula (I) or (Ia), each Q independently represents a cation selected from the group consisting of a proton, an ammonium cation, an alkali metal cation, an alkaline earth metal cation. In a preferred embodiment, each Q independently represents an alkali metal, such as Na or K.

[0151] Polyoxometalates (POMs) can be viewed as clusters of monomeric oxo species of transition metals with one or more bridging oxygen atoms, usually anions. The basic POM framework is named "Y p O y ”, where p and y are the total amount of metal and oxygen ions, respectively. Such POMs are also called heteropolyanions or heteropolyoxometalates. In addition to Y and O, other elements (labeled as X in this article) can be part of the POM framework. Generally, the X element is 4 or 6 coordinated and is located in the Y p O y The center of the shell or cage (X may also be referred to as a "core heteroatom"). If X is present, the POM may be referred to as a heteropolyanion or heteropolyoxometalate, which may be represented by [X z Y p O y ] n- In some embodiments, the POM is a vacant POM, such as [PW 11 O 39 ] 7- .

[0152] "X" can be referred to as a primary or central heteroatom. Generally speaking, any element can participate in the POM cluster as X, as there are no strict physical requirements for this position. Exemplary "X" includes, but is not limited to, B, Si, Ge, P, Al, As, Sb, etc. "Y" can be referred to as a secondary, peripheral, or additional atom. Y can be one or more different metals. Generally, only certain metals are typically found in such compounds. In anions where more than one type of Y addition is present in the framework, the molecule can be referred to as a mixed-addition cluster. Exemplary "Y" includes, but is not limited to, W, Nb, V, Ta, Ti, Zr, Hf, Mo, Zn, In, or Sn.

[0153] In some embodiments, POM is a heteropolyoxometalate, preferably [Q7][PW 11 O 39 ], such as [Na7][PW 11 O 39 In some embodiments, POM is an isopolyoxometalate, preferably [Q8][Nb6O 19 ], such as [K8][Nb6O 19 ].

[0154] In some embodiments, z is 0. In preferred embodiments, X is P, Si, or Al, and / or Y is W, Nb, V, Ta, Ti, Zr, Hf, Mo, Zn, In, or Sn. In particularly preferred embodiments, POM is a heteropolyoxotungstate or an isopolyoxoniobate. A particularly preferred heteropolyoxotungstate is Q7[PW 11 O 39 ], wherein each Q is independently Na or K, preferably wherein Q is Na. A particularly preferred isopolyoxoniobate is Q8[Nb6O 19 ], wherein each Q is independently Na or K, preferably wherein Q is K.

[0155] Each nanoparticle may comprise "r" units of Formula Ib. The number of POMs complexed to a NP "m" may increase as r increases, which varies with the crystal structure. "m" may be any number in the range of 1 to 5,000, and r may be any number in the range of 1 to 20,000. The complex may comprise a POM covalently complexed to a NP.

[0156] In some embodiments, the nanoparticles represented by Formula Ib are crystalline and are referred to herein as nanocrystals.

[0157] In some embodiments, M, M' and M" are each independently Ba, Sr, Ti, Zr, Nb, Hf, Ta, Zn, Al, In, Sn or Ce, optionally in a higher oxidation state. In preferred embodiments, M, M' and M" are each independently Ba(II), Sr(II), Ti(III), Ti(IV), Zr(IV), Nb(V), Nb(III), Hf(IV), Ta(V), Zn(II), Al(III), In(III), Sn(II), Sn(IV) or Ce(IV).

[0158] In particularly preferred embodiments, M' is Ti, optionally Ti(IV) and / or M is Sn, optionally Sn(IV).

[0159] In another preferred embodiment, f is 0. In a more preferred embodiment, f is zero, and k or j is also 0, or k is <1 and j is 1-k. In some embodiments, i and j are each independently a fraction of 1. In some embodiments, the nanoparticles represented by Formula Ib are mixed metal oxides such as Sn i T 1-i O2, wherein i is any fraction between 0 and 1, such as 0.05, 0.12, 0.15, 0.20, 0.25, 0.35, 0.75. The term "fraction of 1" means any fraction between 0 and 1, such as 0.01, 0.008, 0.12, 0.17, 0.23, 0.28, 0.30, 0.35, 0.36, 0.41, 0.47, 0.50, 0.62, 0.77, 0.81, 0.98, or 0.99. A non-limiting example of a mixed metal oxide is Sn .13 Ti .87 O2、Sn 0.54 Ti 0.46 O2、Sn .25 Ti .75 O2 and Sn .5 Ti .5 O2. Mixed metal oxide nanoparticles may also be referred to herein as doped metal oxide nanoparticles. For example, Sn .13 Ti .87 O2 can be referred to as titanium oxide nanoparticles doped with Sn. Mixed metal oxide nanoparticles (such as Sn .13 Ti .87 O2) can allow the refractive index to be tuned by adjusting the ratio between M and M' (eg, Sn and Ti) to find the optimal ratio.

[0160] In some embodiments, the nanoparticles are SnO2, CeO2, ZrO2, TiO2, NbO2, HfO2, or Ta2O5.

[0161] In a preferred embodiment, the complex according to formula (I) is a heteropolyoxotungstate, such as ([Na7][PW 11 O 39 ]), which is mixed with TiO2NP or SnO2NP, or mixed metal oxide NP, such as Sn x T 1-x In another preferred embodiment, the complex according to formula (I) is a polyoxoniobate, such as ([K8][Nb6O 19 ]), which is mixed with TiO2NP or SnO2NP, or mixed metal oxide NP, such as Sn x T 1-x O2NP complexation.

[0162] In a preferred embodiment, the complex according to formula (I) is ([Na7][PW 11 O 39 ]), ([K8][Nb6O 19 ]), and Sn .5 Ti .5 O2 nanoparticles complexed with ([K8][Nb6O 19 ]), and Sn .25 Ti .75 O2 nanoparticles complexed with ([K8][Nb6O 19 ]), and Sn .13 Ti .87 O2 nanoparticles complexed with ([K8][Nb6O 19 ]), (K8[Nb6O 19 ]), and Sn 0.54 Ti 0.46 O2 complexed (K8[Nb6O 19 ]) or Na7[PW complexed with TiO2 nanoparticles 11 O 39 ].

[0163] In a preferred embodiment, the complex according to formula (I) is ([Na7][PW 11 O 39 ]) m (SnO2) r 、([K8][Nb6O 19 ]) m (SnO2) r 、(K8[Nb6O 19 ]) m (Sn .5 Ti .5 O2) r 、([K8][Nb6O 19 ]) m (Sn .25 Ti .75 O2) r 、([K8][Nb6O 19 ]) m (Sn .13 Ti .87 O2) r 、([K8][Nb6O 19 ]) m (Sn .54 Ti .46 O2) r 、([K8][Nb6O 19 ])m (TiO2) r or ([Na7][PW 11 O 39 ] m (TiO2) r , preferably wherein m is any number in the range of 1 to 5000; and r is any number in the range of 1 to 20000, more preferably wherein m is any number in the range of 1 to 1000, and r is any number in the range of 1 to 6000.

[0164] In some embodiments, the formulation further comprises (iii) one or more additives. Each additive can be individually selected from the group consisting of: another complex comprising a polyoxometalate represented by formula (Ia) and nanoparticles represented by formula (Ib), a polyoxometalate represented by formula (Ia), a wetting agent, a dispersant, a viscosity enhancer, a polymer matrix, and a surfactant.

[0165] The presence of one or more additives in the formulation according to the invention can improve the properties of the optical metal oxide layer which is or can be obtained by means of the formulation, such as material hardness, shrinkage, refractive index, transparency, absorption and haze suppression.

[0166] In some embodiments, the formulation further comprises a polyoxometalate represented by formula (I) as an additive. l )[PW 12 O 40 ] or (Q l )[Nb6O 19 ] is a preferred additive. In some embodiments, the polyoxometalate comprises the same elements as the polyoxometalate portion of the complex of formula (I).

[0167] In particularly preferred embodiments, each Q independently represents an alkali metal cation, preferably K or Na.

[0168] In other preferred embodiments, the formulation comprises (i) a first complex represented by formula (I); (ii) one or more formulation media; and (iii) a second complex represented by formula (I), wherein the first complex of formula (I) is not the same as the second complex of formula (I).

[0169] In other preferred embodiments, the formulation comprises (i) a first complex represented by formula (I); (ii) one or more formulation media; and (iii) a second complex represented by formula (I), wherein the first complex of formula (I) is different from the second complex of formula (I).

[0170] In a preferred embodiment, the formulation comprises

[0171] (i) Contains ([Na7][PW 11 O 39 ]) complex,

[0172] (ii) one or more formulation media,

[0173] (iii) another complex comprising ([Na7][PW 11 O 39 ]), and optionally Na3PW 12 O 40 *H2O.

[0174] In a preferred embodiment, the formulation comprises

[0175] (i) a complex comprising a heteropolyoxotungstate, such as ([Q7][PW 11 O 39 ]), or isopolyoxoniobates such as Q8[Nb6O complexed with nanoparticles according to formula (Ib) 19 ],

[0176] (ii) one or more formulation media,

[0177] (iii) polyoxometallates, preferably ([Q l ][PW 12 O 40 ]) or ([Q l ][Nb6O 19 ]).

[0178] Preferred surfactants are surface active substances, which preferably include surface active metal oxides and / or surface active organic compounds. The surface active organic compounds may include nonionic surfactants, anionic surfactants and amphoteric surfactants and may be coordinating or non-coordinating.

[0179] Examples of the nonionic surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene oleyl ether and 30 polyoxyethylene cetyl ether; polyoxyethylene fatty acid diesters; polyoxyethylene fatty acid monoesters; polyoxyethylene polyoxypropylene block polymers; acetylenic alcohols; acetylenic diols; polyethoxylates of acetylenic alcohols; acetylenic diol derivatives such as polyethoxylates of acetylenic diols; fluorine-containing surfactants such as FLUORAD (trade name, manufactured by Sumitomo 3M Limited), MEGAFAC (trade name, manufactured by DIC Cooperation), SURFLON (trade name, manufactured by Asahi Glass Co. Ltd.); or organosiloxane surfactants such as KP341 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like. Examples of the acetylene diol include 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3,6-dimethyl-4-octyne-3,6-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,5-dimethyl-1-hexyn-3-ol, 2,5-dimethyl-3-10-hexyne-2,5-diol, 2,5-dimethyl-2,5-hexane-diol and the like.

[0180] Examples of the anionic surfactant include ammonium salts or organic amine salts of alkyldiphenylether disulfonic acid, ammonium salts or organic amine salts of alkyldiphenylether sulfonic acid, ammonium salts or organic amine salts of alkylbenzenesulfonic acid, ammonium salts or organic amine salts of polyoxyethylene alkyl ether sulfate, ammonium salts or organic amine salts of alkyl sulfate, and the like.

[0181] Examples of the amphoteric surfactant include 2-alkyl-N-carboxymethyl-N-20 hydroxyethylimidazolium betaine, lauric acid amide propyl hydroxysulfone betaine, and the like.

[0182] Preferred surface-active metal oxides are selected from the list consisting of aluminum oxide, calcium oxide, silicon dioxide and zinc oxide. Such surface-active metal oxides are preferably in the form of fine powders, more preferably in the form of nanoparticles that are optionally surface-treated.

[0183] Preferred surface-active organic compounds are surface-active non-polymeric compounds or surface-active polymeric organic compounds, wherein the surface-active non-polymeric compound is preferably selected from the list consisting of alcohols, alkoxylates, aromatics, ketones, esters, modified ureas, silanes, siloxanes and soap-based foam stabilizers, which are optionally functionalized and / or modified; and wherein the surface-active polymeric compound is preferably selected from the list consisting of hydroxy polyesters, maleinate resins, polyacrylates, polyethers, polyesters, polysilanes, silicone resins and waxes, which are optionally functionalized and / or modified; and the surface-active organic compound is optionally present in the form of a copolymer. In a preferred embodiment, the surface-active organic compound is used as a solution.

[0184] Preferred silanes are polyether-modified silanes, polyester-modified silanes, and polyether-polyester-modified silanes. Preferred siloxanes are polyether-modified siloxanes, polyester-modified siloxanes, and polyether-polyester-modified siloxanes.

[0185] Preferred polyacrylates are modified polyacrylates, preferably silicone-modified polyacrylates, polyether macromonomer-modified polyacrylates, and silicone- and polyether macromonomer-modified polyacrylates, optionally in the form of copolymers.

[0186] Preferred polysilanes are polyether-modified polysilanes (eg, PEG-Silane 6-9), polyester-modified polysilanes, and polyether-polyester-modified polysilanes.

[0187] Preferred silicone resins are polyether-modified polysiloxanes, preferably polyether-modified polydialkylsiloxanes, more preferably polyether-modified polymethylalkylsiloxanes, and most preferably polyether-modified polydimethylsiloxanes and polyether-modified hydroxy-functional polydimethylsiloxanes; polyester-modified polysiloxanes, preferably polydialkylsiloxanes, more preferably polyester-modified polymethylalkylsiloxanes, and most preferably polyester-modified polydimethylsiloxanes and polyester-modified hydroxy-functional polydimethylsiloxanes. siloxane; polyether-polyester modified polysiloxane, preferably polyether-polyester modified polydialkylsiloxane, more preferably polyether-polyester modified polymethylalkylsiloxane, and most preferably polyether-polyester modified polydimethylsiloxane and polyether-polyester modified hydroxyl functional polydimethylsiloxane; epoxy functional polysiloxane, preferably epoxy functional polydialkylsiloxane, more preferably epoxy functional polymethylalkylsiloxane, and most preferably epoxy functional polydimethylsiloxane; acryl Functional polysiloxane, preferably acryl-functional polydialkylsiloxane, more preferably acryl-functional polymethylalkylsiloxane, and most preferably acryl-functional polydimethylsiloxane; polyether-modified acryl-functional polysiloxane, preferably a polyether-modified acryl-functional polydialkylsiloxane, more preferably a polyether-modified acryl-functional polymethylalkylsiloxane, and most preferably a polyether-modified acryl-functional polydimethylsiloxane; polyester-modified acryl-functional The present invention further comprises an alkyl-functional polysiloxane, preferably a polyester-modified acryl-functional polydialkylsiloxane, more preferably a polyester-modified acryl-functional polymethylalkylsiloxane, and most preferably a polyester-modified acryl-functional polydimethylsiloxane; and an aralkyl-modified polysiloxane, preferably an aralkyl-modified polydialkylsiloxane, more preferably an aralkyl-modified polymethylalkylsiloxane, and most preferably an aralkyl-modified polydimethylsiloxane; which are optionally present in the form of a copolymer.

[0188] Preferred surfactants are available from BYK-Chemie GmbH, Wesel, Germany and are provided as surface additives. Preferred surfactants are DISPERBYK (hereinafter "BYK") surfactants selected from the following: BYK-300, BYK-301, BYK-302, BYK-306, BYK-307, BYK-310, BYK-313, BYK-315N, BYK-320, BYK-322, BYK-323, BYK-325N, BYK-326, BYK-327, BYK-329, BYK-330, BYK-331, BYK-332, BYK-333, BYK-342, BYK-345, BYK-346, BYK-347, BYK-348, BYK-349, BYK-350, BYK-352, BYK-354, BYK-355, BYK-356, BYK-358N, BYK-359, BYK-360P, BYK-361N, BYK-364P, BYK-366P, BYK-368P, BYK 370, BYK375, BYK-377, BYK-378, BYK-381, BYK-390, BYK-392, BYK-394, BYK-399, BYK-2616, BYK-3400, BYK-3410, BYK-3420, BYK-3450, BYK-3451, BYK-3455, BYK-3456, BYK-3480, BYK-3481, BYK-3499, BYK-3550, BYK-3560, BYK-3565, BYK-3566, BYK-3750, BYK-3751, BYK-3752, BYK-3753, BYK-3754, BYK-3760, BYK-3761, BYK-3762, BYK-3763, BYK-3764, BYK-3770, BYK-3771, BYK-3780, BYK-3900P, BYK 3902P, BYK-3931P, BYK 3932P, BYK-3933P, BYK-8020, BYK-8070, BYK-9890, BYK-DYNWET 800, BYK-S 706, BYK-S 732, BYK-S 740, BYK-S 750N, BYK-S 760, BYK-S 780, BYK-S 782, BYK-SILCELAN 3700, BYK-SILCLEAN 3701, BYK-SILCLEAN 3710, BYK-SILCLEAN 3720, BYK-UV 3500, BYK-UV 3505, BYK-UV 3510, BYK-UV3530, BYK-UV3535, BYK-UV 3570, BYK-UV 3575, BYK-UV 3576; BYKETOL series, such as BYKETOL-AQ, BYKETOL-OK, BYKETOL-PC, BYKETOL-SPECIAL, BYKETOL-WA, NANOBYK series, such as NANOBYK-3603, NANOBYK-3605, NANOBYK-3620, NANOBYK-3650, NANOBYK-3652 and NANOBYK-3822.

[0189] The wetting agents and dispersants used in the present invention are additives that provide wetting and / or stabilization to formulations containing fine solid particles. These additives homogeneously distribute the solid particles in the formulation medium, preferably in a liquid formulation medium, and ensure the long-term stability of such systems. The formulation medium may comprise water and various organic solvents of varying polarity. Furthermore, the formulation medium improves the wettability of the solid and prevents particle flocculation through various mechanisms (e.g., electrostatic interactions, steric effects, etc.).

[0190] Preferably, the wetting agent and dispersant are organic polymers or organic copolymers having polar functional groups selected from the group consisting of: amino groups; amide groups; carbamate groups; carbonate groups; acid groups, preferably boronic acid groups, organic boronic acid groups, carboxylic acid groups, sulfate groups, sulfonic acid groups, phosphoric acid groups, phosphonic acid groups, and phosphinic acid groups; ester groups, preferably borate groups, organic boronic acid groups, carboxylic acid groups, sulfate groups, sulfonic acid groups, phosphate groups, phosphonic acid groups, and phosphinic acid groups; ether groups; hydroxyl groups; ketone groups; and urea groups. The organic polymers or copolymers may be present in the form of conjugates, derivatives, and / or salts, preferably in the form of salts. Preferred salts are ammonium salts, alkylammonium salts, alkanolammonium salts, or alkali metal salts, such as preferably Li, Na, K, and Rb salts. Polar functional groups may also be referred to as pigment-loving groups or filler-loving groups. In a preferred embodiment, the wetting agent and dispersant are used as a solution.

[0191] More preferably, the wetting agent and dispersant are organic polymers or organic copolymers selected from the group consisting of acrylates; amides; carboxylic acids; and esters; wherein the organic polymer or copolymer may be present in the form of a conjugate, derivative, and / or salt, preferably in the form of a salt; and wherein the organic polymer or copolymer may be further functionalized with one or more polar functional groups as described above. Preferred salts are ammonium salts, alkylammonium salts, alkanolammonium salts, or alkali metal salts, such as preferably Li, Na, K, and Rb salts. In a preferred embodiment, the wetting agent and dispersant are used as a solution.

[0192] The wetting agents and dispersants can be present in the form of a mixture, preferably in the form of a mixture with the polysiloxane copolymer.

[0193] Preferred wetting agents and dispersants are available from BYK-Chemie GmbH, Wesel, Germany. Preferred wetting agents and dispersing agents are as follows: ANTI-TERRA-202、ANTI-TERRA-203、ANTI-TERRA-204、ANTI-TERRA-205、ANTI-TERRA-210、ANTI-TERRA-250、ANTI-TERRA-U、ANTI-TERRA-U 80、ANTI-TERRA-U 100、BYK-151、BYK-153、BYK-154、BYK-155 / 35、BYK-156、BYK-220S、BYK-1160、BYK-1162、BYK-1165、BYK-9076、BYK-9077、BYK-GO 8702、BYK-GO 8720、BYK-P 104、BIK-P 104S、BYK-P105、BYK-SYNERGIST 2100、BYK-SYNERGIST 2105、BYK-W 900、BYK-W 903、BYK-W 907、BYK-W908、BYK-W 909、BYK-W 940、BYK-W 961、BYK-W966、BYK-W 969、BYK-W 972、BYK-W 974、BYK-W 980、BYK-W 985、BYK-W 995、BYK-W 996、BYK-W 9010、BYK-W 9011、BYK-W 9012、BYKJET-9131、BYKJET-9132、BYKJET-9133、BYKJET-9142、BYKJET-9150、BYKJET-9151、BYKJET-9152、BYKJET-9170、BYKJET-9171、BYKUMEN、DISPERBYK、DISPERBYK-101 N、DI DISPERBYK-102、DISPERBYK-103、DISPERBYK-106、DISPERBYK-107、DISPERBYK-108、DISPERBYK-109、DISPERBYK-110、DISPERBYK-111、DISPERB YK-115、DISPERBYK-118、DISPERBYK-130、DISPERBYK-140、DISPERBYK-142、DISPERBYK-145、DISPERBYK-161、DISPERBYK-162、DISPERBYK-162 TF、DYSPERBYK-163、DYSPERBYK-163TF、DISPERBYK-164、DISPERBYK-165、DISPERBYK-166、DISPERBYK-167、DISPERBYK-167 TF、DISPERBYK-168、DISPERBYK-168 TF、DISPERBYK-169、DISPERBYK-170、DI SPERBYK-171、DISPERBYK-174、DISPERBYK-180、DISPERBYK-181、DISPERBYK-182、DISPERBYK-184、DISPERBYK-185、DISPERBYK-187、DISPERBYK-190、DISPERBYK-190 BF、DISPERBYK-191、DISPERBYK-192、DI SPERBYK-193、DISPERBYK-194 N、DISPERBYK-199、DI SPERBYK-199 BF、DISPERBYK-2000、DISPERBYK-2001、DI SPERBYK-2008、DISPERBYK-2009、DISPERBYK-2010、DI SPERBYK-2012、DISPERBYK-2013、DISPERBYK-2014、DISPERBYK-2015、DISPERBYK-2015BF、DISPERBYK-2018、DISPERBYK-2019、DI SPERBYK-2022、DISPERBYK-2023、DISPERBYK-2025、DI SPERBYK-2026、DISPERBYK-2030、DISPERBYK-2050、DI SPERBYK-2055、DISPERBYK-2059、DISPERBYK-2060、DI SPERBYK-2061、DISPERBYK-2062、DISPERBYK-2070、DI SPERBYK-2080、DISPERBYK-2081、DISPERBYK-2096、DI SPERBYK-2117、DISPERBYK-2118、DISPERBYK-2150、DI SPERBYK-2151、DISPERBYK-2152、DISPERBYK-2155、DISPERBYK-2155 TF、DISPERBYK-2157、DISPERBYK-2158、DISPERBYK-2159、DISPERBYK-2163、DISPERBYK-2163TF, DISPERBYK-2164, DISPERBYK-2190, DISPERBYK-2200, DISPERBYK-2205, DISPERBYK-2290, DISPERBYK-2291, D ISPERPLAST-1142, DISPERPLAST-1148, DISPERPLAST-1150, DISPERPLAST-1180, DISPERPLAST-I and DISPERPLAST-P.

[0194] Preferred tackifiers are block copolymers, preferably high molecular weight block copolymers; copolymers with functional groups, preferably hydroxyl functional copolymers with acid groups; styrene-ethylene / butyl-styrene block copolymers (SEBS) functionalized with maleic anhydride, carboxyl SEBS functionalized with maleic anhydride, SEBS functionalized with glycidyl methacrylate, polyolefin block copolymers functionalized with maleic anhydride, and ethylene octene copolymers functionalized with maleic anhydride; and polymers with functional groups, preferably polymers with acid groups, and maleic anhydride functionalized polypropylene. In a preferred embodiment, the tackifier is applied as a solution.

[0195] Preferred tackifiers are commercially available from BYK-Chemie GmbH, Wesel, Germany. Preferred tackifiers are the following: BYK-4500, BYK-4509, BYK-4510, BYK-4511, BYK-4512, BYK-4513, SCONA TPKD 8102PCC, SCONA TSIN 4013GC, SCONA TSPOE 1002GBLL, SCONA TPPP 2112FA, SCONA TPPP 2112GA, SCONA TPPP 8112GA, SCONA TSKD 9103, SCONA TPPP 8112FA, SCONA TPKD 8304PCC, and SCONA TSPP 10213GB.

[0196] Preferred polymer matrices are polymethyl methacrylate, polyvinyl pyrrolidone, polycarbonate, polystyrene, polymethylpentene and silicone.

[0197] In some embodiments, one or more formulation media is a solution medium and / or a dispersion medium. In a preferred embodiment, one or more formulation media is selected from water, amides, aromatic hydrocarbons, non-aromatic hydrocarbons, alcohols, carboxylic acids, esters, ethers, ketones, diketones, lactones, and mixtures thereof. In a particularly preferred embodiment, one formulation medium is water. In other particularly preferred embodiments, the formulation medium is water.

[0198] The total content of the complex in the formulation is preferably in the range of 0.1wt% to 25wt%, preferably 0.5wt% to 20wt%, more preferably 1wt% to 12wt% based on the total mass of the formulation. The total content of the complex in the formulation may include one, two, three, four, five or more different complexes. For example, the total content of the complex in the formulation may include the first complex of formula (I) and the second complex of formula (I), wherein the first complex of formula (I) and the second complex of formula (I) are different complexes. The first complex of formula (I) and the second complex of formula (I) can exist in equal amounts. The mass ratio (w / w) between the first complex of formula (I) and the second complex of formula (I) can be in the range of 1:100 to 100:1, preferably 1:10 to 10:1, and more preferably 1:5 to 5:1.

[0199] In a preferred embodiment of the present 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 to 30 mN / m and a viscosity in the range of 5 to 10 mPa·s.

[0200] Preparation method

[0201] According to a second aspect, there is provided a method for producing a formulation comprising the complex described above, wherein the method comprises the following steps:

[0202] a) providing an aqueous solution comprising the complex described above, wherein the complex is present in a range of 0.1 wt % to 10 wt % based on the total amount of the aqueous solution;

[0203] b) Add Q l X p saturated solution, optionally adjusted to a final salt concentration of about 1 M to reversibly precipitate the complex, wherein

[0204] X is a halogen group, such as F, Cl, Br, I, preferably Cl;

[0205] Q is an ammonium cation, an alkali metal cation or an alkaline earth metal cation, preferably Na or K;

[0206] l is any number within the range of 1 to 20, preferably 1 to 10;

[0207] p is any number within the range of 1 to 20, preferably 1 to 10;

[0208] c) centrifugation to obtain the precipitated complex in the form of a pellet;

[0209] d) adding water to the pellets;

[0210] Optionally, e) repeating step b) and step d) one or more times to obtain a slurry;

[0211] f) filtration;

[0212] g) repeating steps b) and d) to obtain a slurry;

[0213] h) subjecting the slurry obtained in step g) to dialysis to obtain a concentrated solution of the complex, wherein the complex is present in the range of 0.1 to 5 wt%, preferably 0.5 to 2.5 wt%, based on the total mass of the formulation.

[0214] In some embodiments, the method further comprises the step h) of further concentrating the solution obtained or obtainable in step g) using a gentle stream of compressed air.

[0215] In some embodiments, the solution obtained or obtainable by step g) is centrifuged to form a bottom layer and a top layer, wherein the bottom layer is redissolved using one or more formulation media to obtain a final concentration of the complex in the range of 2.5 wt% to 25 wt%, preferably 5 wt% to 20 wt%, based on the total mass of the formulation.

[0216] According to an alternative second aspect, there is provided a method for producing a formulation comprising the complex described above, wherein the method comprises the steps of:

[0217] a) providing an aqueous solution comprising the complex described above, wherein the complex is present in a range of 0.1 wt % to 10 wt % based on the total amount of the aqueous solution;

[0218] b) adding an antisolvent such as DMSO, DMF, acetone, isopropanol, methanol, preferably methanol;

[0219] c) centrifugation (and / or filtration) to obtain the precipitated complex in the form of pellets;

[0220] d) adding water to the pellets;

[0221] e) optionally repeating step b) and step c) and step d) one or more times to obtain a purer slurry.

[0222] Conveniently, the use of an antisolvent, particularly methanol, allows for more efficient purification by reducing the number of steps required. Additionally, methanol can be easily removed, for example under reduced pressure. Preferably, the dialysis step can be eliminated.

[0223] And it is believed that a good antisolvent selected (such as DMSO, DMF, acetone, isopropanol, methanol, preferably methanol as mentioned above) precipitates the product without precipitating residual precursors and by-products, and the antisolvent is easy to remove, such as by evaporation.

[0224] Method for producing optical metal oxide layers

[0225] In a third aspect, a method for preparing an optical metal oxide layer is provided, wherein the method comprises the following steps (a) to (c):

[0226] (a) providing a formulation, wherein the formulation comprises:

[0227] (i) a complex comprising a polyoxometalate of formula (Ia) and nanoparticles of formula (Ib); and one or more formulation media;

[0228] (b) applying the formulation to the surface of a substrate; and

[0229] (c) converting the formulation on the surface of the substrate into an optical metal oxide layer.

[0230] In a preferred embodiment of the present invention, the formulation provided in step (a) of the method for preparing an optical metal oxide layer is an ink formulation suitable for inkjet printing. Typical requirements for the ink formulation 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 10 mPa·s.

[0231] In a preferred embodiment of the method for preparing the optical metal oxide layer according to the present invention, the formulation is applied to the surface of the substrate by a deposition method in step (b). Preferred deposition methods are drop 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, lithographic printing, or screen printing. Most preferred are spray coating and inkjet printing.

[0232] Depending on the specific problem to be solved, the formulation needs to be deposited by a coating method as a homogeneous, dense, and thin layer covering the entire surface of the substrate, or the formulation needs to be deposited locally in a structured manner, thus requiring a printing method. Both coating and printing methods require the formulation to be formulated in a suitable manner to meet the physicochemical requirements of the respective coating and printing methods and to meet certain requirements regarding the surface of the substrate to be coated or printed.

[0233] Depending on, for example, the solid content and the trench volume, step (b) is performed one or more times, such as two, three, four, five, six times.

[0234] In a preferred embodiment of the method for preparing the optical metal oxide layer according to 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 Silicon Wafer Cleaning Technology, J. Electrochem. Soc., Vol. 137, 6, 1990, 1887-1892 and New Process Technologies for Microelectronics, RCA Review 1970, 31, 2, 185-454. Such silicon wafer cleaning processes include wet cleaning processes involving cleaning solvents such as isopropyl alcohol (IPA); wet etching processes involving hydrogen peroxide solutions such as piranha solutions SC1 and SC2, choline solutions, or HF solutions; dry etching processes involving chemical vapor etching, UV / ozone treatment, or glow discharge techniques such as O plasma etching; and mechanical processes involving brush scrubbing, fluid jets, or ultrasonic techniques (ultrasonic treatment). The substrate surface can also be pretreated by silanization or atomic layer deposition (ALD) processes. Substrate surface pretreatment is used to modify the hydrophobicity / hydrophilicity of the surface. This can improve the adhesion and filling characteristics of the optical metal oxide layer on the substrate surface.

[0235] In a more preferred embodiment, a wet cleaning process involving a cleaning solvent such as isopropyl alcohol (IPA) is combined with one or more of: a wet etching process involving a hydrogen peroxide solution such as piranha solutions SC1 and SC2, a choline solution, or an HF solution; a dry etching process involving chemical vapor etching, UV / ozone treatment, or glow discharge technology such as O2 plasma etching; and a mechanical process involving brush scrubbing, fluid jet, or ultrasonic technology (ultrasonication).

[0236] In the most preferred embodiment, a wet cleaning process involving a cleaning solvent such as isopropyl alcohol (IPA) is combined with a mechanical process involving brush washing, fluid jet or ultrasonic technology (sonication) and a wet etching process involving a hydrogen peroxide solution such as piranha solutions SC1 and SC2, a choline solution or an HF solution.

[0237] In a preferred embodiment of the present invention, step (b) of the process for producing an optical metal oxide layer is performed several times in sequence, preferably 2 to 20 times, more preferably 2 to 10 times, most preferably 2, 3, 4 or 5 times.

[0238] In a preferred embodiment of the process for producing an optical metal oxide layer according to the invention, the formulation is converted into an optical metal oxide layer in step (c) on the surface of the substrate by exposure to a thermal treatment and / or an irradiation treatment.

[0239] Preferred heat treatments include exposure to elevated temperatures of up to 1200° C., preferably up to 600° C., more preferably up to 550° C., and most preferably up to 500° C. The heat treatment is not limited to any particular heat treatment method or number of times. Depending on the type of substrate and formulation, one skilled in the art will be able to determine the appropriate heat treatment method and number of times.

[0240] Preferred irradiation treatments include exposure to infrared (IR) light, visible (Vis) light, and / or ultraviolet (UV) light. IR light has a wavelength greater than 800 nm. Vis light has a wavelength between 400 and 800 nm. UV light has a wavelength less than 400 nm and may include EUV (extreme UV). The irradiation treatment is not limited to any particular irradiation treatment method or number of times. Depending on the type of substrate and formulation, one skilled in the art will be able to determine the appropriate irradiation treatment method and number of times.

[0241] In a more preferred embodiment of the method for producing an optical metal oxide layer according to the invention, the formulation is converted into an optical metal oxide layer in step (c) on the surface of the substrate by prebaking (soft baking) at a temperature of 40°C to 150°C, preferably 50°C to 120°C, more preferably 60°C to 100°C; and subsequently baking (hard baking, sintering or annealing) at a temperature of 150°C to 600°C, preferably 250°C to 550°C, more preferably 300°C to 500°C.

[0242] Soft baking (also known as pre-baking) is used to remove volatile and low-boiling components (such as volatile and low-boiling formulation media or additives) from the film that has been drop-cast, coated, or printed. Soft baking is preferably performed for a period of 1 to 10 minutes. After soft baking, a substrate-adherent film layer of the metal oxide precursor or metal oxide precursor mixture is obtained. The film may still contain residual formulation media or additives.

[0243] In an alternative, more preferred embodiment of the process for producing an optical metal oxide layer according to the invention, the soft bake can be omitted so that in step (c) the formulation is converted directly into an optical metal oxide layer on the surface of the substrate by baking (hard bake, sintering or annealing) at a temperature of 150° C. to 600° C., preferably 250° C. to 550° C., more preferably 300° C. to 500° C.

[0244] Baking (hard baking, sintering or annealing) is used to convert the metal oxide precursor or metal oxide precursor mixture layer on the substrate into a metal oxide layer. In addition, the final properties of the metal oxide layer can be adjusted by the baking process. Baking is preferably carried out for a period of 1 to 300 minutes, preferably 1 to 60 minutes, to obtain a refractive index (RI) of >1.8.

[0245] The soft bake and hard bake may be performed in ambient atmosphere or in an atmosphere with increased oxygen content to decompose undesirable organic components that may result in a lower activation energy in forming the metal oxide layer.

[0246] In a preferred embodiment of the method for preparing an optical metal oxide layer according to the present invention, the substrate is a patterned substrate comprising topographical features, and the metal oxide forms a coating covering the surface of the substrate and filling the topographical features. Thus, the topographical features are filled and leveled by the metal oxide.

[0247] Preferred topographical features include, for example, gaps, grooves, surface relief gratings, trenches and through-holes. The topographical features may be distributed uniformly or non-uniformly on the surface of the substrate. Preferably, the topographical features are configured as an array or grating on the surface of the substrate. Preferably, the topographical features have different lengths, widths, diameters and different aspect ratios. Preferably, the aspect ratio of the topographical features is 1:20 to 20:1, more preferably 1:10 to 10:1. The aspect ratio is defined as the width of the structure and its height (or depth). From a dimensional perspective, the depth of the topographical features is preferably in the range of 10 nm to 10 μm, more preferably in the range of 50 nm to 5 μm, and most preferably in the range of 100 nm to 1 μm.

[0248] It is also preferred that the topographical features are tilted at an angle, such as an angle of 10° to 80°, preferably 20° to 60°, more preferably 30° to 50°, and most preferably about 40°. Such tilted topographical features are also referred to as tilted or blazed topographical features.

[0249] It may also be necessary to partially fill a topographical feature with the optical metal oxide layer (either completely or to a certain level), but not cover adjacent surfaces of the substrate where the topographical feature to be filled is not accessible.

[0250] Therefore, it is preferred that the method for preparing the optical metal oxide layer according to the present invention further comprises the following step (d):

[0251] (d) removing a portion of the optical metal oxide layer covering the top of the topographical feature, thereby obtaining a filled topographical feature, wherein the coverage of the optical metal oxide layer on top of the topographical feature is reduced, preferably to a coverage between 0 nm and 100 nm, more preferably between 0 nm and 50 nm, and most preferably between 0 nm and 20 nm.

[0252] Step (d) occurs after steps (a) to (c) of the method according to the present invention. Preferably, the portion of the optical metal oxide layer covering the top of the topographical features in step (d) is removed by using the surface cleaning process described above. Preferred surface cleaning processes are silicon wafer cleaning processes such as those described in W. Kern, The Evolution of Silicon Wafer Cleaning Technology, J. Electrochem. Soc., Vol. 137, 6, 1990, 1887-1892 and New Process Technologies for Microelectronics, RCA Review 1970, 31, 2, 185-454. Such silicon wafer cleaning processes include 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 etching, UV / ozone treatment, or glow discharge techniques (e.g., O2 plasma etching); and mechanical processes involving brush scrubbing, fluid jets, or ultrasonic techniques.

[0253] The substrate is preferably a substrate for an optical device. Preferred substrates are made of inorganic or organic base materials, preferably inorganic base materials. Preferred inorganic base materials include materials selected from the group consisting of ceramics, glass, fused silica, sapphire, silicon, silicon nitride, quartz, and transparent polymers or resins. The geometric shape of the substrate is not particularly limited, but preferably it is a thin sheet or wafer.

[0254] In step (b) of the process for producing an optical metal oxide layer, the formulation is applied to the surface of a substrate, wherein the surface may be the surface of the base material of the substrate or the surface of a layer of a material different from the base material of the substrate, wherein such a layer has been formed before applying the formulation.

[0255] In this way, sequences of different layers (layer stacks) can be formed on top of each other. Such layer stacks can also be structured, wherein such structures typically have nanoscale dimensions, at least with respect to diameter, width and / or aspect ratio.

[0256] Use of formulations

[0257] In a fourth aspect, the present invention relates to the use of a formulation for producing an optical metal oxide layer, wherein the formulation comprises: (i) a complex comprising:

[0258] a polyoxometalate moiety represented by formula (Ia), and

[0259] ([Q l ] n+ [X z Y p O y ]) n- (Ia)

[0260] Nanoparticles represented by formula (Ib)

[0261] M i M' j M” f O k (Ib)

[0262] in

[0263] Each Q independently represents a cation, preferably wherein the cation is selected from the group consisting of ammonium cations, alkali metal cations, alkaline earth metal cations,

[0264] l is any number within the range of 1 to 20, preferably 1 to 10;

[0265] n represents the total positive charge n+ of the cation Q and the polyanion [X z Y p O y ] corresponds to the number of negative charges n-;

[0266] X is a heteroatom such as B, Si, Ge, P, Al, As or Sb;

[0267] Y is a metal, preferably a transition metal;

[0268] z is 0 to 20; p is 1 to 100; and y is 2 to 400;

[0269] M, M' and M" are each independently a metal;

[0270] i, j and f are each independently an integer or fraction from 0 to 10; provided that at least one of i, j and f is not 0; and

[0271] k is any number within the range of 1 to 20, preferably 1 to 5; and

[0272] (ii) one or more formulation media.

[0273] Optical device

[0274] In a fifth aspect, an optical device comprising an optical metal oxide layer is provided, which can be obtained by or by the method for preparing the optical metal oxide layer according to the present invention as described above. Preferably, the optical device is an augmented reality (AR) and / or virtual reality (VR) device.

[0275] Preferred Implementation

[0276] Embodiment 1. A formulation for preparing an optical metal oxide layer, wherein the formulation comprises:

[0277] (i) a complex comprising

[0278] a polyoxometalate moiety represented by formula (Ia), and

[0279] (Q l ) n+ [X z Y p O y ] n- (Ia)

[0280] Nanoparticles represented by formula (Ib)

[0281] M i M' j M” f O k (Ib)

[0282] in

[0283] Each Q independently represents a cation, preferably wherein the cation is selected from the group consisting of ammonium cations, alkali metal cations and alkaline earth metal cations,

[0284] l is any number within the range of 1 to 20, preferably 1 to 10;

[0285] n represents the total positive charge n+ of the cation Q and the polyanion [X z Y p O y ] corresponds to the number of negative charges n-;

[0286] X is a heteroatom, preferably B, Si, Ge, P, Al, As or Sb;

[0287] Y is a metal, preferably a transition metal;

[0288] z is 0 to 20; p is 1 to 100; and y is 2 to 400;

[0289] M, M' and M" are each independently a metal;

[0290] i, j and f are each independently an integer or fraction from 0 to 10; provided that at least one of i, j and f is not 0; and

[0291] k is any number within the range of 1 to 20, preferably 1 to 5; and

[0292] (ii) one or more formulation media.

[0293] Embodiment 2. The complex according to embodiment 1, wherein the complex is not Na7[PW complexed with TiO2 11 O 39 ]、Na3[PMo complexed with TiO2 12 O 40 ]、K6[P2W complexed with TiO2 18 O 62 ]、K6[P2Mo complexed with TiO2 18 O 62 ] or Q complexed with TiO2 l [SiW 11 O 39 ], preferably wherein the complex is not Na7[PW complexed with TiO2 11 O 39 ].

[0294] Embodiment 3. The formulation according to embodiment 1, with the proviso that if formula Ib is TiO2, then formula Ia is not Na7[PW 11 O 39 ]、Na3[PMo 12 O 40 ]、K6[P2Mo 18 O 62 ]、K6[P2W 18 O 62 ] or Q l [SiW 11 O 39 ], preferably wherein formula Ia is not Na7[PW 11 O 39 ].

[0295] Embodiment 4. The formulation according to any one of embodiments 1 to 3, wherein the complex is represented by formula (I):

[0296] ([Q l ] n+ [POM] n- ) m (NP) r (I)

[0297] in

[0298] POM is a polyoxometalate represented by formula (Ia);

[0299] NP is a metal oxide or mixed metal oxide nanoparticle represented by formula (Ib);

[0300] m represents the number of polyoxometalate ligands per nanoparticle and is any number in the range of 1 to 5000; and

[0301] r is any number in the range of 1 to 20,000 and represents the empirical metal oxide unit in the nanoparticle.

[0302] Embodiment 5. The formulation according to any of the preceding embodiments, wherein M, M′ and M″ are each independently Ba, Sr, Ti, Zr, Nb, Hf, Ta, Zn, Al, In, Sn or Ce, preferably Ba(II), Sr(II), Ti(III), Ti(IV), Zr(IV), Nb(V), Nb(III), Hf(IV), Ta(V), Zn(II), Al(III), In(III), Sn(II), Sn(IV) or Ce(IV).

[0303] Embodiment 6. The formulation according to any one of the preceding embodiments, wherein M' is Ti and / or wherein M is Sn.

[0304] Embodiment 7. The formulation according to any one of embodiments 1 to 6, wherein i is <1, j is 1-i, and f is 0.

[0305] Embodiment 8. The formulation according to any one of embodiments 1 to 6, wherein the nanoparticles are SnO2, CeO2, ZrO2, TiO2, NbO2, HfO2 or Ta2O5, preferably wherein the nanoparticles are SnO2 or TiO2.

[0306] Embodiment 9. The formulation according to any one of embodiments 1 to 7, wherein the nanoparticles are mixed nanoparticles such as Sn 0.5 Ti 0.5 O2、Sn 0.25 Ti 0.75 O2、Sn 0.54 Ti 0.46 O2 or Sn 0.13 Ti 0.87 O2.

[0307] Embodiment 10. The formulation according to any one of the preceding embodiments, wherein X is P, Ar, Sb, S, Si, Ge, B, Be, Mg, Ca, Sr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga or absent, preferably wherein X is P, Si, Al or absent.

[0308] Embodiment 11. The formulation according to any of the preceding embodiments, wherein Y is W, Nb, V, Ta, Ti, Zr, Hf, Mo, Zn, In or Sn, preferably wherein Y is W or Nb.

[0309] Embodiment 12. The formulation according to any one of the preceding embodiments, wherein the polyoxometalate moiety is a heteropolyoxotungstate or a polyoxoniobate, preferably wherein the polyoxometalate moiety is Na7[PW 11 O 39 ] or K8[Nb6O 19 ].

[0310] Embodiment 13. The formulation according to any one of the preceding embodiments, wherein the formulation comprises (iii) one or more additives.

[0311] Embodiment 14. The formulation according to any one of the preceding embodiments, wherein the one or more additives are each independently selected from the group consisting of: another complex as defined in one or more of embodiments 1 to 12, Na3PW 12 O 40 *nH2O, K8NbO 19 *nH2O, wetting agent, dispersant, tackifier, polymer matrix and surfactant.

[0312] Embodiment 15. The formulation according to any one of the preceding embodiments, wherein the formulation further comprises Na3PW 12 O 40 *nH2O or K8Nb6O 19 *nH2O, and optionally a surfactant such as a polyether-modified silicone.

[0313] Embodiment 16. The formulation according to embodiment 14 or embodiment 15, wherein the other complex is Na7[PW 11 O 39 ]-TiO2.

[0314] Embodiment 17. The formulation according to any one of embodiments 1 to 16, wherein the formulation medium is water.

[0315] Embodiment 18. Use of the formulation according to any one of embodiments 1 to 16 for producing optical metal oxide layers.

[0316] Embodiment 19. A method for preparing an optical metal oxide layer, comprising the steps of:

[0317] (a) providing a formulation according to any one of embodiments 1 to 17;

[0318] (b) applying the formulation to the surface of a substrate; and

[0319] (c) converting the formulation on the surface of the substrate into an optical metal oxide layer.

[0320] Embodiment 20. An optical device, preferably an augmented reality and / or virtual reality device, comprising an optical metal oxide layer, wherein the layer is obtainable by the method according to embodiment 19.

[0321] The present invention is further illustrated by the following examples which should in no way be construed as limiting. It will be appreciated by those skilled in the art that various modifications, additions and alterations may be made to the present invention without departing from the spirit and scope of the invention as defined in the appended claims.

[0322] Example

[0323] List of abbreviations:

[0324] NP nanoparticles

[0325] ·POM polyoxometalate

[0326] Conc. concentration

[0327] Cald. calculation

[0328] RI refractive index n

[0329] Materials and methods

[0330] Material:

[0331] K7[PW] was prepared following known procedures. 11 O 39 ]*nH2O. (Haraguchi et al., Inorg. Chem. 2002, 33(6):1015-1020.)

[0332] ·K8[Nb6O 19 ]*nH2O. (Kong,

[0333] · Prepare Na3[PW 12 O 40]*nH2O. (Phillips, MA (1950), The preparation of phosphotungs ticacidand of s odium and ba rium phosphotungs tates.J.Chem.Technol.Biotechnol.,69:282-284.ht tps: / / doi.org / 10.1002 / jctb.5000690906)

[0334] • A 25 wt% BYK348 aqueous solution was prepared by adding 0.375 g (0.375 ml) of ultrapure water (Milli-Q) to 0.125 g (0.118 ml) of BYK348.

[0335] BYK348 was purchased from BYK-Chemie GmbH.

[0336] By adding 4.5g of water to 0.5g of Na3PW 12 O 40 *nH2O to prepare 10wt% Na3PW 12 O 40 *nH2O aqueous solution (PW-A).

[0337] By adding 4.5g of water to 0.5g of K8Nb6O 19 *nH2O to prepare 10wt% K8Nb6O 19 *nH2O 10wt% aqueous solution (NbO-A).

[0338] • Cellulose dialysis membrane (Spectra / Por 1 dialysis membrane MWCO: 6-8,000, nominal flat width 40 mm) was pre-treated prior to use according to the manufacturer.

[0339] General methods for detection and characterization

[0340] 1) Inductively coupled plasma optical emission spectrometry (ICP-OES).

[0341] A SPECTROARCOS FHM22 instrument equipped with a vertical plasma torch box (SOP) was used. Data were acquired and analyzed using the Smart Analyzer Vision software. Samples were diluted to meet the instrument concentration range and measured without further processing.

[0342] 2) Ellipsometry

[0343] Ellipsometry was used to determine the layer thickness, refractive index (n), and absorptivity (k) of the metal oxide layer. The measurements were performed using an alpha SE ellipsometer from JA Woollam at three different angles of incidence (65°, 70°, and 75°). The measured data were analyzed using the CompleteEase software from JA Woolam, assuming complete or almost complete transparency above a wavelength of 600 nm, and applying a Cauchy fit to determine the refractive index (n) and absorptivity (k). The optical constants were averaged from three different measurements of the sample after soft or hard baking.

[0344] Membrane preparation:

[0345] For ellipsometry measurements, materials were deposited by spin coating on Si substrates (untreated or piranha solution treated) from aqueous solutions at 2000 RPM for 25 seconds, soft-baked at 100°C for 1 minute, and then hard-baked at 300°C for 10 minutes.

[0346] Film thickness is typically in the range of 35 nm to 300 nm.

[0347] Scanning electron microscopy (SEM)

[0348] SEM images were recorded using a HR-SEM Sirion or an ultra-high resolution scanning electron microscope Magellan 400L (ThermoFisher, formerly FEI).

[0349] 3) Calculation of the estimated diameter of POM-NP

[0350] Figure 15A Schematic diagram of a NP (100) with radius R (106) complexed with m POMs (where m = 9). Also shown are the projections (104) of some POMs onto the spherical surface of the NP. Figure 15B , the same projection is shown for the case where the radius of the NP is much larger than the radius of the POM, and where the NP is shown as a planar surface to illustrate the packing of the POM spheres.

[0351] The following calculations will provide an estimate of the effective radius of the nanoparticle (core) using the following notations and assumptions:

[0352] Table 1: Parameters used to calculate the estimated diameter of POM-NPs.

[0353]

[0354]

[0355] aFor the mixed oxide cores, a weighted average of the molecular weights was used.

[0356] bFor NP, including

[0357] Only SnO2 (cassiterite) ρ is considered to be 6.95 g / cm 3 (e.g., Example 1, Example 2);

[0358] Only TiO2 (anatase) ρ is considered to be 3.78 g / cm 3 (e.g., Example 9a, Example 9b);

[0359] Only TiO2 (amorphous) ρ is considered to be 3.00 g / cm 3 (For example, Example 6, Example 7);

[0360] The average value of ρ assumed for mixed Sn / TiO2NPs is 4.23 g / cm 3 (For example, Example 3, Example 4, Example 5, Example 8).

[0361] c POM effective radius, r POM , which were used based on values obtained from Weinstock et al., J. Am. Chem. Soc. 2009, 131, 47, 17412-17422; and Nyman et al., J Clust Sci, 2006, 17: 197-219.

[0362] The following assumptions are made:

[0363] 1. The core (NP) is spherical. 2. The number of POM covering the NP is less than the number of "core units" (such as TiO2).

[0364] 3. Not considering the curvature of the core NP in geometric modeling

[0365] 4. All metal atoms are in the form of metal oxides and are part of the NP core

[0366] 5. All POM transition metal atoms are in POM form and attached to the surface of NPs

[0367] First, the mass of the NP is calculated using equation (i) assuming a spherical structure with radius R and density of the associated crystal structure ρ.

[0368]

[0369] Subsequently, the number of core-formula units r is calculated by dividing the mass by the molecular weight MW using formula (ii).

[0370]

[0371] Assume that the core radius is larger than the POM radius (R>r POM ) and ignoring the curvature of NP, the following is the derivation of the formula for the NP radius.

[0372] The number of NPs in 1 liter is calculated by dividing the concentration of the metal element (eg, Ti), [M], by the number of elements in a single core, r.

[0373] The number of NPs in 1 liter is given by [M] / r.

[0374] The number of POM per liter is given by formula (iii):

[0375] (iii) [POM] = m*[M] / r

[0376] Equation (iii) can be used to calculate m by inserting (i) and (ii):

[0377]

[0378] The surface area of NP is given by A = 4πr 2 Given, and the area of the projection of a single POM on the core is

[0379] The total area of the projection of the POM on the surface of the NP is calculated by multiplying the area of the POM by the number of POMs per NP, as shown in equation (iv):

[0380]

[0381] The total surface area of the core's projection is also given by multiplying the core's surface area by a filling factor that takes into account the covering efficiency of a closed packing set of circles over a given area:

[0382] NP* surface (filling factor) = (the sum of the projections of the POM on the NP)

[0383] And using the above formula:

[0384]

[0385] Finally, R is given by:

[0386]

[0387] Nanoparticle size is not uniform across this synthesis and can vary depending on the exact composition and synthesis method. Therefore, in this calculation format, average parameters, including the NP radius, are assumed. Furthermore, as mentioned above, various approximations are made, and experimental errors exist in the measured values [POM] and [M]. Therefore, the average radius is expected to be within ±30% of the calculated radius, and even wider variance can be expected within the distribution.

[0388] General preparation method

[0389] 1) Surface pretreatment and formulation deposition

[0390] The piranha solution treated substrates were immersed in H2SO4 (concentration) mixed with H2O2 (30%) at a ratio of 3:1 for 20 min and then washed with distilled water until the pH of the water was neutral (at least 9 times). The substrates were dried using an air gun.

[0391] The coating of wafers (square Si / SiO2, AF45 glass or 18x18 mm Si / SiN structured substrates) was performed using a spin coater from Os sila. The spin coating process using a flat substrate was as follows: 0.1 ml of the coating was deposited onto the wafer, followed by spinning at 2000 rpm for 25 seconds. The coating procedure for the structured substrate was as follows: 0.1 ml of the coating was deposited onto the wafer with a residence time of 1 min, followed by spinning at 2000 rpm for 25 seconds. After spin coating, the coated substrate was soft-baked at 100°C for 1 minute to remove solvent residues, and then cured at high temperature. Typically, but not limited to, the coated layer was hard-baked at 300°C, 400°C and 500°C for 10 minutes. A high-temperature hot plate that allowed temperatures up to 500°C to be reached was used for soft baking and layer curing.

[0392] 2) Substrate with groove structure

[0393] The structured substrate (usually a silicon wafer) is used as a square die with an edge length of 1.5 cm to 2 cm. The wafer die is cut and cleaved from the mother wafer, which is typically 8" in diameter. The structure is produced and arranged on a SiO2 / SiN x In the layer stack formed, the layer stack is deposited onto the wafer surface. The dimensions of the structure (e.g., the cross-sectional width and length of the grooves) refer to the architecture of Sematech mask 854. Generally, but not limited to, cross-sectional cleavages perpendicular to the groove array providing a width of 40nm to 50nm are used as the main groove structure of interest to study the filling of the structure by metal oxide. In addition to the foregoing, cross-sectional views of groove arrays with widths of 100nm and 150nm are used to study the groove filling by metal oxide.

[0394] Unless otherwise noted, the structured wafer dies were coated by spin coating. For this purpose, a volume of coating formulation of typically 0.1 ml per die was pipetted and cast onto the surface of the wafer. The wafer dies were spun at 2000 rpm for 25 seconds. The soft bake and hard bake conditions for the structured wafer dies were selected to be similar or identical to those already mentioned for the non-grooved substrates.

[0395] Preparation of POM-complexed nanoparticles

[0396] Example 1: Preparation of [α-PW complexed with SnO2 nanoparticles 11 O 39 ] 7-

[0397] SnCl4.5H2O (926 mg, 2.64 mmol) was added to deionized water (198 mL) as a solid. The mixture was stirred for 2 h by adding aqueous LiOH (160 mM, about 66 mL, 10.6 mmol) followed by K7[α-PW 11 O 39 ] aqueous solution (20mM, 66mL, 1.32mmol) and adjusted to pH 4.5. The reaction mixture was stirred at 25°C for two hours, transferred to a 316 stainless steel reaction vessel lined with polytetrafluoroethylene (Teflon) and heated in an oven (120°C, 24 hours), and then cooled to room temperature on the laboratory bench. 11 O 39 ] 7- Optically clear solution.

[0398] Separation. Saturated NaCl solution was added to the cooled reaction mixture to a final salt concentration of 1 M, resulting in reversible precipitation of complex 1. The turbid solution was centrifuged (6000 rpm, 5 min), the supernatant was discarded, and the pellet was redissolved in water. Two additional separation cycles of salt addition, centrifugation, and pellet redissolution were performed. The solution was then filtered using a Millex-HV syringe filter unit (0.45 μm, PVDF, 33 mm) to remove any large impurities. A minimum amount of water was used to dissolve the pellet to prepare a mixture containing [α-PW complexed with SnO2 nanoparticles]. 11 O 39 ] 7- The slurry was subjected to additional separation cycles with excess NaCl.

[0399] Purification. The slurry was transferred to a treated cellulose membrane bag and then placed in a 1 L water bath for dialysis (16 hours, with water changed after one hour). Thereafter, the [α-PW complexed with SnO2 nanoparticles] 11 O39 ] 7- A purified, completely dissolved and concentrated (approximately 1% w / v) solution of

[0400] Concentration. The dialyzed solution was further concentrated to a concentration of 8.5% (wt %) using a gentle stream of compressed air.

[0401] The films were prepared as described under the heading “2) Ellipsometry” and the results of the ellipsometry are shown in Table 2.

[0402] Example 2. Preparation of [Nb6O complexed with SnO2 nanoparticles 19 ] 8-

[0403] Deionized water (342 mL) was added to solid SnCl4·5H2O (938 mg, 2.68 mmol). KOH aqueous solution (400 M, about 26.9 mL 10.8 mmol) was added, followed by K8Nb6O 19 The pH was adjusted to 10.5 with an aqueous solution (20 mM, 66 mL, 1.32 mmol). The reaction mixture was stirred at 25°C for two hours, transferred to a 316 stainless steel reaction vessel lined with polytetrafluoroethylene and heated in an oven (120°C, 24 hours), and then cooled to room temperature on the bench. 19 ] 8- Optically clear solution.

[0404] [Nb6O] complexed with SnO2NPs was carried out as described above for complex 1. 19 ] 8- The separation, purification and concentration of the product were carried out as described above, except that a saturated KCl solution was used instead of NaCl and the product was concentrated to a final concentration of 12 wt%.

[0405] The films were prepared as described under the heading “2) Ellipsometry” and the results of the ellipsometry are shown in Table 2.

[0406] Example 3: Preparation and Sn 0.5 Ti 0.5 O2 nanoparticles complexed with [Nb6O 19 ] 8-

[0407] Solid SnCl4.5H2O (18.4 mg, 52.5 μmol) was added to deionized water (12.0 mL), followed by aqueous KOH (400 mM, 0.23 mL, 91 μmol). Subsequently, a freshly prepared titanium isopropoxide solution diluted in isopropanol (40 mM, 4 mL, 160 μmol) was added dropwise with vigorous stirring to produce a cloudy white suspension. The solution was stirred for 30 minutes, after which K8[Nb6O 19 ] aqueous solution (20 mM, 4 mL, 80 μmol). The reaction mixture was stirred for another two hours at 25°C, transferred to a 316 stainless steel reaction vessel lined with polytetrafluoroethylene and heated in an oven (120°C, 20 hours), and then cooled to room temperature on the laboratory bench. 0.54 Ti 0.46 O2NP complexed [Nb6O 19 ] 8- of solution.

[0408] Isolation and purification were performed as described in Example 1, except that a saturated solution of KCl was used instead of NaCl.

[0409] The dialyzed solution was centrifuged (18000 rcf, 1 hour) to separate the Sn 0.54 Ti 0.46 O2NP complexed [Nb6O 19 ] 8- transferred to the bottom, thereby producing a dense transparent layer (containing Sn 0.54 Ti 0.46 O2 complexed high concentration [Nb6O 19 ] 8- ) and a thinner top layer. Discard the top layer and redissolve the bottom layer with a small amount of water to make the Sn 0.54 Ti 0.46 O2NP complexed [Nb6O 19 ] 8- The final concentration was 15.1 wt%.

[0410] The films were prepared as described under the heading “2) Ellipsometry” and the results of the ellipsometry are shown in Table 2.

[0411] Example 4. Preparation of Sn 0.25 Ti 0.75 O2 nanoparticles complexed with [Nb6O 19 ] 8-

[0412] The method described in Example 3 was used with adjusted amounts of SnCl4·5H2O (9.3 mg, 26 μmol), deionized water (11.76 mL), KOH aqueous solution (400 mM, 0.26 mL, 104 μmol) and a certain amount of K8[Nb6O 19 ](4mL, 80μmol) will be combined with Sn 0.25 Ti 0.75 O2NP complexed [Nb6O 19 ] 8- Synthesize, isolate, purify and concentrate.

[0413] The product was concentrated to 9.2 wt% at pH 10.

[0414] The films were prepared as described under the heading "2) Ellipsometry", and the results of the ellipsometry are shown in Table 2. (Example 4a)

[0415] Another film was prepared as per the heading "2) Ellipsometry", but hard baked at 200°C instead of 300°C. The results of the ellipsometry are shown in Table 2. (Example 4b)

[0416] Example 5. With Sn 0.13 Ti 0.87 O2 nanoparticles complexed with [Nb6O 19 ] 8-

[0417] The method described in Example 3 was used with adjusted amounts of SnCl4·5H2O (7.2 mg, 20 μmol), deionized water (11.42 mL), aqueous KOH (400 mM, 0.58 mL, 230 μmol) and the same amount of K8[Nb6O 19 ](4mL, 80μmol) will be combined with Sn 0.13 Ti 0.87 O2NP complexed [Nb6O 19 ] 8- Synthesis, separation, purification and concentration.

[0418] Will contain Sn 0.13 Ti 0.87 O2 complexed [Nb6O 19 ] 8- The solution was concentrated to a concentration of 17.7 wt %. Subsequently, the solution was diluted four times to obtain a final concentration of 4.4 wt %.

[0419] The films were prepared as described under the heading “2) Ellipsometry” and the results of the ellipsometry are shown in Table 2.

[0420] Example 6. Preparation of [Nb6O complexed with TiO2 nanoparticles 19 ] 8-

[0421] Aqueous KOH solution (400 mM, 4.5 mL, 1.8 mmol) was added to deionized water (178.3 mL), followed by the dropwise addition of a freshly prepared titanium isopropoxide solution diluted in isopropanol (40 mM, 59.4 mL, 2.38 mmol) with vigorous stirring, resulting in a slightly turbid white suspension. 19 ] aqueous solution (20 mM, 59.4 mL, 1.19 mmol). The reaction mixture was then refluxed (80° C., 24 h) to obtain a solution containing complex 6. Isolation and purification were performed in a manner similar to that described in Example 1, except that a saturated KCl solution was used instead of NaCl; a concentrated solution of the product was obtained using the concentration method described in Example 3.

[0422] Contains [Nb6O complexed with TiO2 nanoparticles 19 ] 8- The final concentration of the solution was 18.6 wt%.

[0423] Films were prepared as described under the heading "2) Ellipsometry" and the results of the ellipsometry are shown in Table 2. (Example 6a).

[0424] The [Nb6O 19 ] 8- The solution of 18.6% w / v was diluted twice to reach a concentration of 9.8 wt%.

[0425] Films were prepared as described under the heading "2) Ellipsometry" and the results of the ellipsometry are shown in Table 2. (Example 6b).

[0426] Example 7. Preparation of [Nb6O complexed with TiO2 nanoparticles 19 ] 8-

[0427] The synthesis, isolation, purification and concentration were carried out using the protocol described in Example 6, but instead of refluxing, the reaction was heated hydrothermally. 19 ] solution, the reaction mixture was stirred at 25°C for one hour, transferred to a 316 stainless steel reaction vessel lined with polytetrafluoroethylene and heated in an oven (180°C, 20 hours), and then cooled to room temperature on the bench.

[0428] The obtained nanostructured particles [Nb6O 19 ]8- of solution (5.2wt%).

[0429] The films were prepared as described under the heading “2) Ellipsometry” and the results of the ellipsometry are shown in Table 2.

[0430] Example 8. Preparation of Sn .13 Ti .87 O2 nanoparticles complexed with [α-PW 11 O 39 ] 7-

[0431] Solid SnCl4·5H2O (103 mg, 0.294 mmol) was added to deionized water (293 mL). Subsequently, a freshly prepared solution of titanium isopropoxide in isopropanol (10% v / v, 9 mL, 3.1 mmol) was added dropwise with vigorous stirring to produce a turbid white suspension. The mixture was stirred for 2 h by adding aqueous KOH (0.4 M, approximately 3 mL, 1.2 mmol), followed by the addition of K7[α-PW 11 O 39 ]*nH2O (3.71 g, 1.17 mmol) was added to adjust the pH to 4.5. The reaction mixture was stirred at 25°C for three hours, transferred to a 316 stainless steel reaction vessel lined with polytetrafluoroethylene and heated (120°C, 17 hours), and then cooled to room temperature on the laboratory bench. .13 Ti .87 O2 nanoparticles complexed with [α-PW 11 O 39 ] 7- of solution.

[0432] The samples were isolated and purified as described in Example 1.

[0433] Concentration. The solution was concentrated by following the method described in Example 3 to a final concentration of 9.4 wt%.

[0434] The Sn-Sn bond was measured after a soft bake at 100°C (8a) for one minute and after subsequent heating periods (hard bake) of 10 minutes at 300°C (8b), 400°C (8c) and 500°C (8d). .13 Ti .87 O2 nanoparticles complexed with [PW 11 O 39 ] 7- The results of ellipsometry are shown in Table 2.

[0435] An optimum appears to be reached at 300°C with maximum RI.

[0436] The shrinkage between 100°C (for 1 minute) and 300°C is about 5%.

[0437] Example 9a-b. Preparation of [α-PW complexed with TiO2 nanoparticles 11 O 39 ] 7-

[0438] Example 9a

[0439] Under vigorous stirring, a freshly prepared 10% titanium isopropoxide solution in isopropanol (8.9 mL, 3.0 mmol) was added dropwise to 369 mL of deionized water to produce a cloudy white suspension. Thereafter, K7[α-PW 11 O 39 ]*nH2O (4.79 g, 1.51 mmol). The reaction mixture was then stirred at 25°C for 10 minutes, transferred to a 316 stainless steel reaction vessel lined with polytetrafluoroethylene and heated in an oven (170°C, 20 hours), and then cooled to room temperature on the bench. 11 O 39 ] 7- Optically clear solution.

[0440] The [α-PW complexed with TiO2 nanoparticles was carried out as described in Example 1. 11 O 39 ] 7- separation and purification.

[0441] Concentrate. Follow the procedure described in Example 3 to obtain a concentrated solution, yielding 10.7 wt%.

[0442] The films were prepared as described under the heading “2) Ellipsometry” and the results of the ellipsometry are shown in Table 2.

[0443] Example 9b

[0444] A freshly prepared solution of titanium isopropoxide diluted in isopropanol (40 mM, 59.4 mL, 2.38 mmol) was added dropwise to deionized water (178 mL) with vigorous stirring to produce a cloudy white suspension. K7[α-PW 11 O 39 ] aqueous solution (20 mM, 59.4 mL, 1.19 mmol). The reaction mixture was then stirred at 25°C for one hour, transferred to a 316 stainless steel reaction vessel lined with polytetrafluoroethylene and heated in an oven (180°C, 20 hours), and then cooled to room temperature on the bench. 11 O39 ] 7- Optically clear solution.

[0445] The separation and purification of the solution were performed as described in Example 1. The concentration method described in Example 3 was used to achieve a 10.1 wt% concentrated solution.

[0446] The films were prepared as described under the heading “2) Ellipsometry” and the results of the ellipsometry are shown in Table 2.

[0447] Table 2. Summary of ellipsometry data (thickness, n and k), material concentration in aqueous solution and calculated estimated diameters.

[0448]

[0449]

[0450] As can be seen from Table 2, the complex obtained in Example 4 exhibited the highest refractive index among the complexes having different Sn to Ti ratios, indicating that the optimal element ratio between Sn and Ti is 0.25 to 0.75. Furthermore, Example 8 showed that the optimum seems to be reached at 300°C. The shrinkage rate between 100°C and 300°C for 1 minute was approximately 5%.

[0451] The presence of both counterions "K" and "Na" in Examples 1, 8, and 9 can be easily explained by looking at the synthetic pathways. It is understood that "K" is derived from the precursor K7[α-PW 11 O 39 ]*The remaining residues of H2O.

[0452] Table 3: ICP-OES measurements of purified materials.

[0453]

[0454]

[0455] The above embodiments demonstrate the realization of the technical objectives of the present invention.

[0456] Alternative solvent-based purification methods

[0457] For the preparation of Sn x Ti 1-x O2 nanoparticles complexed with [Nb6O 19 ] 8- Synthesis scheme of

[0458] Solid SnCl4*H2O (140 mg, 399 μmol) was added to deionized water (173 mL). KOH solution (1 M, 1.4 mL, 1.4 mmol) was added to the mixture to adjust the pH to 10.3. Freshly prepared titanium isopropoxide solution (40 mM, 730 μL, 2.49 mmol titanium isopropoxide, diluted with 61.52 mL of isopropanol) and K8[Nb6O] were simultaneously added to the tin solution in a slow and steady stream (approximately 30 seconds). 19 ] aqueous solution (1.686 g, 1.25 μmol, dissolved in 62.25 mL of water) was added with vigorous stirring. The reaction mixture was then stirred for about 3 hours, after which the mixture was transferred to a 316 stainless steel reaction vessel lined with polytetrafluoroethylene and heated in an oven at 120°C for 20 hours. The reaction vessel was then cooled to room temperature to obtain a mixture containing Sn x Ti 1-x O2 nanoparticles complexed with [Nb6O 19 ] 8- of solution.

[0459] Precipitation-based purification method (Purification method 1)

[0460] Purification method 2 involves precipitating the product from the reaction mixture by adding a saturated solution of KCl until a 1M KCl concentration is reached. Under these conditions, the nanocrystals reversibly aggregate and precipitate, while the majority of the molecular clusters remain in solution. The precipitate is separated from the supernatant by centrifugation and decantation and can subsequently be redissolved in water using the same volume of solvent as the reaction itself or with a volume of approximately one-sixth the reaction volume. The precipitation, centrifugation, and redissolution steps (one purification cycle) are repeated three times.

[0461] The resulting nanocrystal solution will contain excess KCl, which limits the solubility of the product to about 1 wt %. To enhance solubility, dialysis was performed for 18 hours to remove excess KCl and some of the K of the hexaniobate ligand. + counterions, leaving 6 to 8 K per ligand + ions. The remaining relative cations are protons (0 to 2 H + ). This removal of KCl enables further concentration of the aqueous solution to greater than 5 wt% product by air evaporation.

[0462] Solvent-based purification method for removing molecular by-products via addition of solvent (Purification Method 2)

[0463] In a typical procedure, methanol is added until 10% volume is reached, thus obtaining a mixed solvent system of methanol, isopropanol and water. This step is followed by centrifugation and the pellet obtained is redissolved in water or filtered (depending on the scale).

[0464] result:

[0465] The dissolved pellets and supernatant solutions obtained after the two purification methods (Purification Method 1 and Purification Method 2) were compared using data from UV-Vis, FTIR and ICP spectroscopy after a single cycle of precipitation, separation and re-dissolution. 7A to 7B and Figure 8 , and Table 4) 1 .

[0466] 7A to 7B Shown is a comparison of the UV-VIS spectra of a diluted sample of the supernatant solution (A) and a diluted sample of the lysate (B) obtained using purification methods 1 and 2.

[0467] Figure 8 FT-IR spectra of dried samples of the products obtained using purification methods 1 and 2 are shown.

[0468] The resulting molar ratios between the elements of the separated products obtained by ICP-OES measurement are shown in Table 4.

[0469] Table 4. Molar ratios between elements of the separated products measured by ICP-OES.

[0470] The data were obtained after only one purification cycle, which means that the obtained nanoparticles may not have been completely purified. Additional purification cycles may require different solvent systems to separate the remaining by-products.

[0471] sample K Nb Sn Ti Purification method 1 2.54 1 0.18 0.96 Purification method 2 0.91 1 0.19 0.91

[0472] "Combined method" (combined purification methods 1 and 2)

[0473] After purification via purification method 1, the solution was reprecipitated using KCl, followed by centrifugation. The pellet obtained was dispersed into a 1:1 water-methanol mixture of 1 / 5 the initial sample volume, centrifuged, and the pellet was redissolved in pure water.

[0474] Table 5 shows the molar ratios between the elements of the separated products measured by ICP-OES.

[0475] Table 5. Molar ratios between elements of the separated products measured by ICP-OES.

[0476] sample K Nb Sn Ti Purification method 1 13.85 1 0.43 1.53 Purification method 2 1.43 1 0.41 1.50

[0477] Combined method samples of each [Nb6O 19 ] 8- Clusters contain excess 0.6K + ions, while the standard method samples each [Nb6O 19 ]8- Clusters contain excess 75K + ion.

[0478] The results in Tables 4 and 5 can be further optimized by repeating the purification cycles, adjusting the nature of the added solvent or the relative ratios of the solvent mixture, or by lowering the pH to control the protonation state of the ligand in the product, which affects the solubility and separation after the addition of organic solvent.

[0479] Additional solvent systems:

[0480] It is also possible to consider adding other solvents to the isopropyl alcohol-water mixture. For example, Figure 9 Shown are the reaction mixtures after addition of 10% (v / v) additional solvents such as DMSO, DMF, acetone, methanol, acetonitrile, resulting in a mixed organic-aqueous solvent system.

[0481] Figure 10 Display K8Nb6O 19 Pure solution in a mixed solvent system of added solvent, isopropanol and water.

[0482] Preparation of formulations containing complexes of varying sizes or additional polyoxometalate ligands

[0483] The purpose of the following experiments was to test whether adding smaller POM-NP complexes to larger POM-NP complexes would result in a coating with an increased refractive index.

[0484] General approach:

[0485] The material was vortex mixed for 15 seconds at room temperature.If necessary, the material was diluted in water by heating at 50°C for 10 minutes and mixing using a vortex.

[0486] Example M1

[0487] An aqueous solution of "PW-SnO2" (8.5 wt%, Example 1) and an aqueous solution of "PW-TiO2" (10.7 wt%, Example 9a) were mixed in the amounts indicated in Table 4.

[0488] The results of the ellipsometry measurements are shown in Table 6.

[0489] Table 6. Mixture of PW-SnO2 (8.5 wt%) and PW-TiO2 (10.7 wt%) and the resulting refractive index

[0490]

[0491] Table 6 shows that mixing PW-TiO2 and PW-SnO2 at various ratios results in higher refractive indices compared to pure PW-TiO2 or PW-SnO2 materials, respectively. Adding a small amount of PW-SnO2 to PW-TiO2 appears to be particularly beneficial in achieving higher refractive indices, with the highest refractive indices being achieved with PW-TiO2 weight fractions of 0.90 to 0.94.

[0492] Figure 11 The refractive index dependence of the PW-TiO2 weight fraction of PW-TiO2 / PW-SnO2 mixtures is shown.

[0493] Example M2

[0494] An aqueous solution of "PW-TiO2" (10.7 wt%, Example 9a) was mixed with an aqueous solution of "PW-A" (10 wt%) in the amounts indicated in Table 7.

[0495] The results of the ellipsometry measurements are shown in Table 7.

[0496] Table 7. Mixture of PW-TiO2 and PW-A

[0497]

[0498]

[0499] Increasing the amount of PW increases the refractive index up to 2.074 at a weight fraction of 0.31 PW-A. Additional amounts of PW-A decrease the refractive index at a smaller slope than increases in weight fractions < 0.31.

[0500] A refractive index of 2.093 was achieved with a different batch of PW-TiO2 at a weight fraction of 0.35. The prepared film also had an extinction coefficient of 0.003.

[0501] Figure 12 The refractive index of a mixture comprising PW-TiO2 and PW-A is shown as a function of the PW-TiO2 wt% content, measured on films deposited on Si substrates and hard-baked at 300°C.

[0502] Example M3:

[0503] An aqueous solution of "PW-SnO2" (8.5 wt%, Example 1) was mixed with an aqueous solution of "PW-TiO2" (10.7 wt%, Example 9a) to obtain a weight fraction of PW-TiO2 of 0.94 (see Table 3). In addition, an aqueous solution of PW-A (9.5 wt%) was added in the amount indicated in Table 8.

[0504] Table 8. Refractive index after adding different amounts of PW-A aqueous solution to a PW-TiO2 / PW-SnO2 stock solution in a volume ratio of 13 / 1 in water.

[0505] PW-A weight fraction N at 520nm k at 460nm 0 1.930 0 0.062 1.942 0.0086 0.209 1.998 0.0091 0.346 2.018 0.0006 0.514 2.044 0.0061

[0506] As can be seen from Table 8, the addition of PW-A to the mixture of PW-TiO2 / PW-SnO2 increases the refractive index.

[0507] Figure 13 Shows the refractive index of the PW-TiO2 / PW-SnO2 mixture and the change in the amount of added PW-A.

[0508] Example M4

[0509] The amount of "NbO-Sn .25 Ti .75 An aqueous solution of "O2" (9.2 wt%, Example 4) was mixed with a "NbO-A" solution (10 wt%). Films were prepared from the resulting formulations. The results of the ellipsometry measurements are shown in Table 9.

[0510] Table 9. NbO-Sn containing NbO-A solution .25 Ti .75 Mixing volume of O2 (9.2 wt%) solution and ellipsometry results.

[0511]

[0512] a Hard bake at 300℃.

[0513] b Hard baked at 400℃.

[0514] For baking temperatures of 300°C and 400°C, the 1.8 / 1 wt% ratio of NbO-Sn .25 Ti .75 O2 / NbO-A produces films with higher refractive indices: 1.997 at 300°C and 2.033 at 400°C.

[0515] When the NbO-APOM content is high, the extinction parameter k is significantly higher.

[0516] Made of pure NbO-Sn .25 Ti .75 The thickness of the film prepared by O2 is 92nm, RI is 1.968, and k is 0.0031. The addition of NbO-APOM increases the RI.

[0517] Example M5 (mixed material 7 and material 15)

[0518] An aqueous solution of "NbO-TiO2" (5.2 wt%, Example 7) was mixed with a solution of "NbO-A" (10 wt%) in the amounts indicated in the table.

[0519] Table 10. Optical properties of films mixed with NbO-TiO2 and NbO-A, deposited from the resulting formulations and baked at 300°C for 10 min.

[0520]

[0521] The addition of POM increases the RI compared to the results obtained in Example 7 (RI = 1.880, k = 0.0009). As can be seen in Table 10, the highest RI is achieved for a wt% ratio (NbO-TiO2 / NbO-A) of RI = 1.992.

[0522] Example M6

[0523] The amount of "PW-Sn .13 Ti .87 An aqueous solution of "O2" (9.4 wt%, Example 8) was mixed with a "PW-A" solution (10 wt% PW-A aqueous solution).

[0524] Table 11. PW-Sn .12 Ti .87 Optical properties of films deposited from O2 mixed with PW-A formulations and baked at 300°C for 10 min.

[0525]

[0526] For high content NbO-A ligands, the extinction parameter k is not significantly higher as in the case of higher SnO2 content particles.

[0527] Table 12. Selected ellipsometry data of the individual materials mixed with POM or with another POM-NP (Examples M1 to M6).

[0528]

[0529] 1 TiO2 at 0.94wt%

[0530] The refractive index n and extinction parameter k shown in Table 12 were measured after a soft bake at 100°C followed by a hard bake at 300°C. This temperature was chosen because it provides advantages for device fabrication using these formulations. However, as can be seen in Examples M4.4, M4.5, and M4.6, higher refractive index n values can be achieved when baked at higher temperatures.

[0531] in conclusion:

[0532] Selected results from Examples M1 to M6 are summarized in Table 12. It can be seen that adding a small amount (6 wt%) of smaller POM-NPs to larger POM-NPs produces a surprising increase in refractive index (Table 10, M1). Adding a POM ligand to the POM-NPs was also beneficial in all tested examples (Table 10, M2-6). Adding PW-A to the PW-SnO2 / PW-TiO2 solution (6% PW-SnO2) further increased the refractive index to 2.04, with a lower k (Table 12: M3).

[0533] Trench filling experiment

[0534] Example T1: PW-SnO2

[0535] The solution obtained in Example 1 was diluted to a concentration of 5 wt% PW-SnO2 aqueous solution. The 5 wt% solution was used to deposit the trench sample following the procedure described above in "Substrates with a trench structure".

[0536] Briefly, a solution containing PW-SnO2 (5 wt%, 0.1 mL) was deposited on a Si substrate treated with piranha solution and then spun at 2000 rpm for 25 seconds. The substrate was soft-baked at 100°C for 1 min and then hard-baked at 300°C for 10 min. The cross-sectional SEM image is shown in Figure 14 In. Figure 14 As shown in FIG, large voids are formed in the trenches. This may be a result of incomplete gap filling due to poor penetration and adhesion of POM-NPs to the trench surface during the heating stage.

[0537] Example T2-A: BYK348 additive containing PW-SnO2

[0538] An aqueous solution of PW-SnO2 (8.5 wt %; Example 1) was mixed with an aqueous solution of BYK348 (0.5 wt %) in water.

[0539] After mixing, the droplets were cast onto a SiN surface with a groove structure. The grooved substrate was prepared as described above (see section "Substrates with a grooved structure"). The SEM images obtained are shown in Figure 15A As can be seen, a complete trench filling is obtained.

[0540] Example T2-B: BYK348 additive containing PW-SnO2

[0541] To investigate the optical properties of films containing BYK348 additive, a formulation of 8.5 wt % PW-SnO2 containing 0.5 wt % BYK348 aqueous solution was prepared.

[0542] An additional film was deposited on the grooved substrate using a spin coating technique. For this formulation, the grooves were partially filled and voids appeared after hard baking at 200°C, as shown in FIG. Figure 15B shown in.

[0543] exist Figure 15B As can be seen in the SEM images in Figure 2, there is only partial filling (about 50%) and some small side voids appear, but the filling is consistent with the Figure 14 The filling shown in the figure is better.

[0544] Example T2-C: BYK348 Additive with Ellipsometry from Example #2

[0545] [Nb6O complexed with SnO2NP 19 ] -8 An aqueous solution (12 wt %, described in Example 2) was mixed with the aqueous solution containing BYK348 to achieve 0.5 wt % BYK348.

[0546] A Si wafer was used as a substrate for the film ends, and the refractive index and extinction coefficient were measured after the film was soft-baked at 100° C. for 1 min and hard-baked at 300° C. for 10 min.

[0547] Compared with the material obtained in Example 2, the obtained material has a lower refractive index.

[0548] The results of the ellipsometry measurements are shown in Table 13.

[0549] Example T3

[0550] A formulation of PW-SnO2 (Example 1) containing the POM additive PW-A was prepared in a weight ratio of 0.85 / 1, similar to the technique described in Example M2. 100 μL of 8.5 wt% PW-SnO2 material and 100 μL of PW-A material were taken.

[0551] The formulation was deposited as a thin film on a Si substrate and after soft baking at 100°C for 1 minute and hard baking at 300°C for 10 minutes.

[0552] The results of the ellipsometry measurements are listed in Table 13.

[0553] The formulations were deposited by spin coating on the grooved samples and the SEM images of the cross sections are shown in Figure 16 middle.

[0554] This formulation produces a better trench fill than the pure material described in Example 1 (PW-SnO2), which is similar to the trench fill after spin coating with BYK 348. However, BYK 348 reduces the RI.

[0555] Example T4: NbO-Sn .25 Ti .75 O2+NbO-A

[0556] The formulation is described above in Example M4.

[0557] After soft baking at 100 °C for 1 min, spin coating was applied to the grooved samples. Figure 17A ) and 87.5nm trench ( Figure 17B ) width SEM image showing partial filling.

[0558] After hard baking at 300°C for 10 minutes (after soft baking at 100°C for 1 minute), the filled portion has a trench width of 84 nm ( Figure 17C ).

[0559] Example T5: NbO-Sn .25 Ti .75 O2+NbO-A

[0560] To obtain complete trench filling, a double layer deposition technique was performed using the same formulation as in Example T4.

[0561] After deposition of both layers, the first sample was prepared with a single soft bake step (100° C. for one minute). Figure 18A and Figure 18B Shows surface feature filling of spin-coated mixture NbO-SnO2\TiO225 / 75%+NbO-A after soft baking at 100℃ for 1 min. The groove width is 114nm ( Figure 18A ) and 131nm( Figure 18B ).

[0562] exist Figure 18A In the figure, the two trenches on the right are filled almost to the top of the trench. However, they are not completely filled. Figure 12 Wider gaps of >130 nm are depicted in B.

[0563] Figure 18C A sample made with two layers (no soft bake between layers) is shown (soft bake after the second layer and hard bake at 300° C.) It can be seen that the remaining gaps are filled and no voids are present.

[0564] Table 13. Ellipsometry data for Examples T1 to T5.

[0565]

Claims

1. A formulation for producing an optical metal oxide layer, wherein the formulation comprises: (i) a complex comprising a polyoxometalate moiety represented by formula (Ia), and (Q l ) n+ [X z Y p O y ] n- (Ia) Nanoparticles represented by formula (Ib) M i M' j M” f O k (Ib) in Each Q independently represents a cation, l is any number in the range of 1 to 20; n represents the total positive charge n+ of the cation Q and the polyanion [X z Y p O y ] corresponds to the number of negative charges n-; X is a heteroatom; Y is a metal; z is 0 to 20; p is 1 to 100; and y is 2 to 400; M, M' and M" are each independently a metal; i, j and f are each independently an integer or fraction from 0 to 10; provided that at least one of i, j and f is not 0; and k is any number in the range of 1 to 20; and (ii) one or more formulation media.

2. The complex according to claim 1, wherein the complex is not Na7[PW 11 O 39 ]、Na3[PMo complexed with TiO2 12 O 40 ]、K6[P2W complexed with TiO2 18 O 62 ]、K6[P2Mo complexed with TiO2 18 O 62 ] or Q complexed with TiO2 l [SiW 11 O 39 ].

3. The formulation according to claim 1, with the proviso that if formula Ib is TiO2, then formula Ia is not Na7[PW 11 O 39 ]、Na3[PMo 12 O 40 ]、K6[P2Mo 18 O 62 ]、K6[P2W 18 O 62 ] or Q l [SiW 11 O 39 ].

4. The formulation according to any one of claims 1 to 3, wherein the complex is represented by formula (I): ([Q l ] n+ [POM] n- ) m (NP) r (I) in POM is a polyoxometalate represented by formula (Ia); NP is a metal oxide or mixed metal oxide nanoparticle represented by formula (Ib); m represents the number of polyoxometalate ligands per nanoparticle and is any number in the range of 1 to 5000; and r is any number in the range of 1 to 20,000 and represents the empirical metal oxide unit in the nanoparticle.

5. The formulation according to any one of the preceding claims, wherein M, M′ and M″ are each independently Ba, Sr, Ti, Zr, Nb, Hf, Ta, Zn, Al, In, Sn or Ce, preferably Ba(II), Sr(II), Ti(III), Ti(IV), Zr(IV), Nb(V), Nb(III), Hf(IV), Ta(V), Zn(II), Al(III), In(III), Sn(II), Sn(IV) or Ce(IV).

6. The formulation according to any one of the preceding claims, wherein M' is Ti and / or M is Sn.

7. The formulation according to any one of claims 1 to 6, wherein i is <1, j is 1-i, and f is 0.

8. The formulation according to any one of claims 1 to 6, wherein the nanoparticles are SnO2, CeO2, ZrO2, TiO2, NbO2, HfO2 or Ta2O5.

9. The formulation according to any one of the preceding claims, wherein X is P, Ar, Sb, S, Si, Ge, B, Be, Mg, Ca, Sr, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga or is absent.

10. The formulation according to any one of the preceding claims, wherein Y is W, Nb, V, Ta, Ti, Zr, Hf, Mo, Zn, In or Sn.

11. The formulation according to any one of the preceding claims, wherein the polyoxometallate moiety is a heteropolyoxotungstate or a polyoxoniobate.

12. The formulation according to any one of the preceding claims, wherein the formulation comprises (iii) one or more additives, wherein the one or more additives are each independently selected from the group consisting of: other complexes as defined in any one of claims 1 to 11, Na3PW 12 O 40 *nH2O, K8NbO 19 *nH2O, wetting agent, dispersant, tackifier, polymer matrix and surfactant.

13. The formulation according to any one of the preceding claims, wherein the formulation further comprises Na3PW 12 O 40 *nH2O or K8Nb6O 19 *nH2O, and optionally a surfactant such as a polyether-modified silicone.

14. A method for preparing an optical metal oxide layer, comprising the following steps: (a) providing a formulation according to any one of claims 1 to 13; (b) applying the formulation to the surface of a substrate; and (c) converting the formulation on the surface of the substrate into an optical metal oxide layer.

15. An optical device, preferably an augmented reality and / or virtual reality device, comprising an optical metal oxide layer, wherein the layer is obtainable by the method according to claim 14.

16. Use of a formulation according to any one of claims 1 to 13 for producing optical metal oxide layers or optical devices.

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