Highly transparent rare earth nanoparticle / caged polysilsesquioxane composite photoresist, and preparation method and application thereof

Abstract

The application discloses a kind of high transparent rare earth nanoparticles / cage polysilsesquioxane composite photoresist and its preparation method and application, the photoresist includes the composite matrix consisting of cage polysilsesquioxane, multifunctional acrylate and photoinitiator, and the rare earth nanoparticles modified by bifunctional ligand.The bifunctional ligand anchors nanoparticles by first functional group, and forms chemical bonding with matrix by second functional group, realizes the atomic level uniform dispersion of nanoparticle.The photoresist has very high optical transparency, high-efficiency up-conversion luminescence performance and very high ultraviolet photosensitivity.Its preparation process is simple, without high-temperature expensive equipment, can be adapted to a variety of photo-curing technology realizes the integration precision forming of complex three-dimensional structure luminescence device, has wide application prospect in integrated photonics device field.

Description

Technical Field

[0001] This application relates to the field of rare earth polymer composite material preparation technology, and mainly to a highly transparent rare earth nanoparticle / cage-shaped polysilsesquioxane composite photoresist and its preparation method and application. Background Technology

[0002] Rare earth-doped luminescent materials (such as Er) 3+ Tm 3+ Yb 3+ Rare-earth light-emitting devices (RADs) play an irreplaceable role in fields such as fiber optic communication, fiber lasers, sensing, displays, and bioimaging due to their unique energy level structures. With the rapid development of integrated photonics and micro / nano optics technologies, the market demand for micro / nano devices with active light-emitting capabilities is increasing. Traditional rare-earth light-emitting device manufacturing typically relies on high-temperature processes such as chemical vapor deposition (MCVD) and melt-drawing. While these technologies are mature, the equipment is expensive and the processes are complex, making it difficult to meet the customized requirements of modern optical devices for complex three-dimensional structures and spatially selective doping.

[0003] In recent years, to expand the application of light-emitting optical fibers and micro / nano devices in integrated photonics, researchers have attempted to introduce rare-earth nanoparticles (RE-NPs, such as NaYF4:Yb, Er) into polymer matrices, aiming to achieve flexible fabrication of light-emitting devices using photopolymerization molding technology. However, existing technological approaches have significant limitations: traditional processes such as chemical vapor deposition involve multiple steps of high-temperature vapor deposition and sintering, requiring extremely high equipment precision and making it difficult to flexibly fabricate complex structures or functionally graded optical fibers. In the emerging composite material approach, rare-earth nanoparticles are often coated with long-chain organic ligands such as oleic acid, which have extremely poor compatibility with common polar photoresist matrices and are prone to aggregation. This aggregation not only produces severe physical light scattering, significantly reducing the transparency and light transmission efficiency of the material, but also causes concentration quenching, reducing luminescence efficiency.

[0004] Furthermore, the fabrication of transparent light-emitting materials (such as luminescent glass and optical fibers) is often limited by traditional molding processes. Methods such as melt drawing and preform stretching are difficult to rapidly fabricate complex three-dimensional structures, microchannels, or customized optical fiber networks. Although 3D printing technology based on two-photon polymerization provides a new approach for the fabrication of micro- and nano-optical devices, the resin material systems suitable for this technology are limited, especially photoresist materials that combine high transparency, good formability, and efficient rare-earth luminescence. Common polymer-based photoresists are prone to aging and yellowing under high temperatures or long-term light exposure, while inorganic glass materials are difficult to directly perform high-precision 3D printing. This makes balancing the requirements of "high transparency," "efficient luminescence," and "precision processing suitability" a major challenge.

[0005] In summary, developing a novel composite photoresist system that can achieve uniform dispersion of rare earth nanoparticles in a photoresist matrix to maintain high transparency, and is compatible with high-precision photopolymerization technology, thereby preparing a complex three-dimensional structure, excellent stability, and high-efficiency light-emitting performance, is of great scientific significance and application value for promoting the development of next-generation integrated and customized photonic devices. Summary of the Invention

[0006] To address the technical problems in existing technologies, such as the tendency of rare earth nanoparticles to agglomerate, leading to decreased transparency, and the difficulty of achieving precision machining of complex three-dimensional light-emitting structures using traditional molding processes, this application proposes a highly transparent rare earth nanoparticle / cage-like polysilsesquioxane composite photoresist, its preparation method, and its application.

[0007] According to one aspect of the present invention, a highly transparent rare-earth nanoparticle / cage-like polysilsesquioxane composite photoresist is provided, comprising a cage-like polysilsesquioxane composite matrix and rare-earth nanoparticles modified with bifunctional ligands; the bifunctional ligands include a first functional group for anchoring on the surface of the rare-earth nanoparticles, and a second functional group that forms a chemical bond with the cage-like polysilsesquioxane composite matrix through a photopolymerization reaction; the cage-like polysilsesquioxane composite matrix comprises cage-like silsesquioxane, a prepolymer monomer, and a photoinitiator.

[0008] This approach utilizes bifunctional ligands to construct covalent bonds between rare-earth nanoparticles and cage-like polysilsesquioxane matrices. The first functional group is anchored to the surface of the rare-earth nanoparticles through chemical chelation, while the second functional group participates in the free radical polymerization reaction of the matrix under photoinitiation, locking the rare-earth nanoparticles in situ within a three-dimensional cross-linked network. This strategy alters the traditional physical doping mode, mechanically and thermodynamically suppressing the migration and secondary aggregation of rare-earth nanoparticles during the molding process. It significantly reduces refractive index mismatch and physical scattering loss at the interface, enabling the composite material to achieve highly efficient active light emission while maintaining extremely high optical transmittance.

[0009] Preferably, the bifunctional ligand comprises mono[2-(2-methacryloyloxy)ethyl] succinate.

[0010] More preferably, the structure of the succinate mono[2-(2-methacryloyloxy)ethyl] ester is as follows:

[0011] .

[0012] The carboxyl group at the end of succinic acid mono[2-(2-methacryloyloxy)ethyl] ester has a high affinity for rare earth ions and can effectively replace the original long-chain alkyl ligands such as oleic acid on the surface of nanoparticles through ligand exchange reactions, thereby improving the dispersion stability of the particles in polar monomers. The methacryloyl group at the other end has similar reaction kinetics characteristics to acrylate monomers in the matrix, ensuring the consistency of crosslinking density and thus improving the structural uniformity of the cured product.

[0013] Preferably, the rare earth nanoparticles comprise fluoride, oxide, or vanadate nanocrystals doped with luminescent ions; the luminescent ions include Yb 3+ Er 3+ and Tm 3+ At least one of them.

[0014] More preferably, the rare earth nanoparticles include NaYF4:Yb,Er upconversion luminescent nanoparticles or NaYF4:Yb,Tm upconversion luminescent nanoparticles. Using low-phonon-energy fluorides, oxides, or vanadates as the main lattice matrix can maximally suppress the nonradiative transition probability of rare earth ions.

[0015] Preferably, the cage-like silsesquioxane comprises acryloyloxypropyl cage-like polysilsesquioxane, the prepolymer monomer comprises a multifunctional acrylate, and the photoinitiator comprises phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. Acryloyloxypropyl cage-like polysilsesquioxane introduces an inorganic silicon-oxygen framework, endowing the composite system with excellent heat resistance, UV aging resistance, and high hardness. Meanwhile, the multifunctional acrylate, acting as a reactive diluent and crosslinking center, forms a high-density network of nodes during curing through its multifunctional structure, significantly reducing curing shrinkage and ensuring the morphological fidelity of the micro / nano structure after photolithography.

[0016] According to a second aspect of the present invention, a method for preparing a highly transparent rare-earth nanoparticle / cage-like polysilsesquioxane composite photoresist is provided, comprising the following steps:

[0017] S1. The rare earth nanoparticles are surface modified using the bifunctional ligand to obtain modified rare earth nanoparticles with polymerizable groups on their surface.

[0018] S2. The modified rare earth nanoparticles are mixed with the cage-like silsesquioxane, prepolymer monomer and photoinitiator and uniformly dispersed to obtain the composite photoresist.

[0019] This method employs a "modification-then-dispersion" process. First, the particle surface is functionalized using phase transfer or solvothermal methods to impart mesotropic properties. Then, in-situ mixing technology ensures that the modified particles achieve a uniform molecular-level distribution within the viscous cage-like polysilsesquioxane composite matrix. This process avoids the phase separation risk caused by direct mixing, guaranteeing the chemical stability of the photoresist during long-term storage.

[0020] Preferably, the mass ratio of the cage-like silsesquioxane, prepolymer monomer, and photoinitiator is (90-91):(8-10):(0.4-0.6). The high content of cage-like silsesquioxane ensures the glass-like properties of the material, while the specific ratio of prepolymer monomer and photoinitiator guarantees that the photoresist has suitable photosensitivity and reaction rate under ultraviolet exposure.

[0021] According to a third aspect of the present invention, a three-dimensional transparent light-emitting device is proposed, which is fabricated by photocuring a highly transparent rare-earth nanoparticle / cage-like polysilsesquioxane composite photoresist.

[0022] Preferably, the three-dimensional transparent light-emitting device includes at least one of optical fiber, optical waveguide and photonic crystal, or includes an integrated structure composed of at least two of the optical fiber, optical waveguide and photonic crystal.

[0023] Based on the excellent processing adaptability of this photoresist, spatially selective curing technologies such as digital light processing (DLP) or stereolithography (SLA) can be used to precisely shape complex three-dimensional geometries. The fabricated devices possess both high transparency and high-efficiency light emission, and their physicochemical properties are stable, effectively overcoming the limitations of traditional wire drawing processes in fabricating irregular, micro-scale, and functionally integrated optical structures.

[0024] Compared with the prior art, this application has the following beneficial effects:

[0025] (1) This application achieves a transformation of the surface properties of rare earth nanoparticles from hydrophobic to polymerizable affinity through an innovative ligand exchange process. The modified rare earth nanoparticles are covalently locked in situ within a three-dimensional cross-linked network of cage-like polysilsesquioxane in the form of "macromonomers," transforming the nanoparticles from traditional "physical doping points" into "chemical cross-linking points" of the matrix. Utilizing this molecular-level confinement effect, this scheme can effectively suppress the migration and secondary aggregation of particles during molding and storage, achieving atomic-level dispersion of rare earth nanoparticles in photoresist. This fundamentally eliminates interface defects and physical light scattering caused by phase separation, ensuring that the material maintains chemical homogeneity at the microscale while exhibiting extremely high optical transparency at the macroscale.

[0026] (2) The preparation method provided in this application is free from the dependence on high temperature environment and complex and expensive equipment of traditional melt drawing or chemical vapor deposition processes. The device can be manufactured by conventional chemical surface modification and photocuring processes. This solution greatly reduces the preparation threshold and cost of high-performance transparent light-emitting devices and provides a feasible path for the large-scale production of rare earth doped micro and nano optical components.

[0027] (3) Based on the excellent processability of composite photoresist, this scheme allows for arbitrary arrangement and encoding of rare-earth light-emitting units in three-dimensional space, enabling the integrated precision molding of complex irregular structures such as irregular optical waveguide networks, photonic crystals, and microchannels. The fabricated devices possess both high transparency and efficient active light-emitting function, providing unprecedented flexibility for the design and expansion of next-generation highly integrated and customized photonic chips and multifunctional optoelectronic devices. Attached Figure Description

[0028] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of this application. Other embodiments and many anticipated advantages of these embodiments will be readily recognized as they become better understood through reference to the following detailed description. Elements in the drawings are not necessarily to scale. The same reference numerals refer to corresponding similar parts.

[0029] Figure 1 A schematic diagram of surface modification of rare earth nanoparticles according to an embodiment of this application is shown;

[0030] Figure 2 A schematic diagram of the preparation process of a highly transparent rare earth nanoparticle / cage-like polysilsesquioxane composite photoresist according to an embodiment of this application is shown.

[0031] Figure 3 A schematic diagram of the molding process of a transparent light-emitting device using a highly transparent rare-earth nanoparticle / cage-shaped polysilsesquioxane composite photoresist according to an embodiment of this application is shown.

[0032] Figure 4 A schematic diagram of the preparation process of a highly transparent rare earth nanoparticle / cage-like polysilsesquioxane composite photoresist according to a specific embodiment of this application is shown;

[0033] Figure 5 The transmittance spectrum of a transparent luminescent bulk material of NaYF4: 18%Yb, 2%Er according to a specific embodiment of this application is shown.

[0034] Figure 6The fluorescence spectrum of a NaYF4:18%Yb,2%Er composite photoresist according to a specific embodiment of this application is shown.

[0035] Figure 7 The transmittance spectrum of a transparent luminescent bulk material, NaYF4: 20%Yb, 1%Tm, according to a specific embodiment of this application, is shown.

[0036] Figure 8 The fluorescence spectrum of a NaYF4: 20%Yb, 1%Tm composite photoresist according to a specific embodiment of this application is shown.

[0037] Figure 9 This illustration shows a schematic diagram of the forming process of a transparent light-emitting device using a highly transparent rare-earth nanoparticle / cage-like polysilsesquioxane composite photoresist according to a specific embodiment of this application.

[0038] Figure 10 An optical microscope image of a micropatterned device according to a specific embodiment of this application is shown. Detailed Implementation

[0039] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0040] Where there is no conflict, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] A highly transparent rare earth nanoparticle / cage-like polysilsesquioxane composite photoresist comprises a cage-like polysilsesquioxane composite matrix and rare earth nanoparticles modified with bifunctional ligands.

[0042] Specifically, the bifunctional ligand is mono[2-(2-methacryloyloxy)ethyl] succinate, with the following structural formula:

[0043] ,

[0044] It includes a first functional group for anchoring onto the surface of rare earth nanoparticles, namely the carboxyl group at the end of the molecule, and a second functional group, namely the methacryloyl group located at the other end of the molecule, which forms a chemical bond with the cage-like polysilsesquioxane composite matrix through photopolymerization.

[0045] Figure 1 This is a schematic diagram of surface modification of rare earth nanoparticles, such as... Figure 1As shown, the carboxyl group at the end of succinic acid mono[2-(2-methacryloyloxy)ethyl] ester has a high affinity for rare earth ions and can effectively replace the original long-chain alkyl ligands such as oleic acid on the surface of nanoparticles through ligand exchange reactions, thereby improving the dispersion stability of the particles in polar monomers.

[0046] The methacryloyl group at the other end can participate in free radical polymerization. Based on this, the surface properties of rare earth nanoparticles change from hydrophobic to an affinity surface with polymerizable active groups. This allows the nanoparticles to directly participate in the crosslinking reaction of cage-like polysilsesquioxanes as "macromonomers" during photocuring. This molecular-level confinement effectively inhibits the migration and aggregation of nanoparticles during solvent evaporation and polymerization shrinkage, thus maintaining the chemical homogeneity of the components at the microscale. By eliminating interfacial defects caused by phase separation, the composite material exhibits excellent optical isotropy on a macroscopic scale, minimizing scattering losses during light propagation and ensuring that the device maintains high upconversion luminescence intensity while possessing high transparency to meet the requirements of precision optical applications.

[0047] Specifically, rare earth nanoparticles include fluoride, oxide, or vanadate nanocrystals doped with luminescent ions; the luminescent ions include Yb 3+ Er 3+ and Tm 3+ At least one of them.

[0048] In specific embodiments, rare earth nanoparticles include NaYF4:Yb,Er upconversion luminescent nanoparticles or NaYF4:Yb,Tm upconversion luminescent nanoparticles. Through Yb... 3+ / Er 3+ or Yb 3+ / Tm 3+ The energy transfer system allows the material to achieve a highly efficient upconversion process under 980nm near-infrared light excitation, outputting highly saturated green and blue light respectively, providing a stable active light-emitting center for micro-nano optical devices.

[0049] Specifically, the cage-like polysilsesquioxane composite matrix includes cage-like silsesquioxane, prepolymer monomer and photoinitiator, with a mass ratio of (90-91):(8-10):(0.4-0.6).

[0050] In a specific embodiment, the cage-like silsesquioxane is acryloyloxypropyl cage-like polysilsesquioxane, the prepolymer monomer is ethoxylated trimethylolpropane triacrylate, and the photoinitiator is phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPOs) or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO).

[0051] Figure 2This is a schematic diagram illustrating the fabrication process of the highly transparent rare-earth nanoparticle / cage-like polysilsesquioxane composite photoresist, for reference. Figure 2 The specific steps are as follows:

[0052] S1. Take an appropriate amount of oleic acid-coated rare earth nanoparticles and disperse them in cyclohexane to form a dispersion. Then, add liquid succinic acid mono[2-(2-methacryloyloxy)ethyl] ester to the dispersion to obtain a preliminary mixture. Next, stir the preliminary mixture at room temperature and then treat it with ultrasound to obtain a mixed solution. Finally, centrifuge the mixed solution, discard the supernatant, and collect the viscous liquid in the lower layer to obtain a concentrated dispersion of surface-modified rare earth nanoparticles.

[0053] S2. Weigh appropriate amounts of cage-like silsesquioxane, prepolymer monomer, and photoinitiator and dissolve them in dichloromethane solvent to obtain a uniform and transparent photoresist precursor solution. Mix the concentrated dispersion of rare earth nanoparticles with the photoresist precursor solution at a mass ratio of 1:1, add dichloromethane to dissolve completely, and then place in a light-protected room temperature environment with continuous stirring. After the dichloromethane solvent evaporates naturally, a uniform, viscous, highly transparent rare earth nanoparticle / cage-like polysilsesquioxane composite photoresist can be obtained.

[0054] Figure 3 This is a schematic diagram of the fabrication process for a transparent light-emitting device based on this highly transparent rare-earth nanoparticle / cage-like polysilsesquioxane composite photoresist. (Refer to...) Figure 3 The specific steps are as follows:

[0055] A1. Spin-coat the photoresist directly onto a clean substrate to obtain a uniform and smooth film. The spin-coating parameters are: 500 rpm / 5s, followed by 1000 rpm / 30s.

[0056] A2. Align the mask with the target pattern (such as micro lines or dot matrix) with the coated substrate and perform contact exposure using an ultraviolet light source with a main wavelength of 365nm.

[0057] A3. After exposure, the substrate is directly immersed in propylene glycol methyl ether acetate (PGMEA) for development. The photoresist in the unexposed areas is dissolved and removed. Then, it is rinsed with isopropanol and dried with nitrogen. Because the exposed areas have been completely cured through a covalent network, they have excellent solvent resistance and clear pattern edges.

[0058] Example 1

[0059] A highly transparent upconversion luminescent composite photoresist based on the NaYF4:Yb,Er system, the preparation method of which can be found in [reference needed]. Figure 4 The specific steps are as follows:

[0060] S101. Take 0.4 mmol of oleic acid-coated NaYF4:18%Yb,2%Er nanoparticles and disperse them in 4 mL of cyclohexane to obtain a dispersion. Add approximately 600 μL of succinic acid mono[2-(2-methacryloyloxy)ethyl] ester directly to the dispersion to obtain a preliminary mixture. Place the preliminary mixture under ambient temperature and pressure and magnetically stir, supplemented with intermittent sonication, for 30 min to obtain a mixed solution. During this process, the carboxyl terminus of the liquid ligand molecule undergoes in-situ coordination exchange with the rare earth ions on the surface of the nanoparticles, effectively replacing the original oleic acid ligand. After the reaction is complete, centrifuge the mixed solution at 5000 rpm for 5 min, discard the supernatant, and collect the viscous colloidal liquid at the bottom to obtain a concentrated dispersion of surface-modified rare earth nanoparticles.

[0061] S102. Weigh 90.5% acryloyloxypropyl cage-like silsesquioxane (POSS1013), 9% ethoxylated trimethylolpropane triacrylate, and 0.5% BAPOs photoinitiator, and place them together in a sample vial. Add 10 mL of dichloromethane (DCM) as a solvent to the sample vial, and after dissolution, a uniform and transparent photoresist precursor solution is obtained. Mix the concentrated dispersion of rare earth nanoparticles with the photoresist precursor solution at a mass ratio of 1:1, and add dichloromethane to dissolve it completely. Then, place it in a light-protected room temperature environment and stir continuously for 24 hours. During this process, the dichloromethane gradually evaporates naturally, and the viscosity of the system increases accordingly, eventually forming a uniform, stable, and viscous composite photoresist suitable for coating or casting.

[0062] The highly transparent upconversion luminescent composite photoresist based on the NaYF4:Yb,Er system was placed on a clean substrate and then irradiated with a 5W ultraviolet point light source with a dominant wavelength of 365nm at a distance of approximately 5cm. Experimental results show that the composite system exhibits extremely high photosensitivity, achieving complete curing within just 5 seconds of ultraviolet irradiation to obtain a transparent composite glassy solid. This solid is clear and transparent under natural light and emits bright green upconversion fluorescence under 980nm near-infrared laser excitation. This characteristic indicates that the composite system of this invention is highly suitable for applications requiring rapid prototyping, such as continuous 3D printing.

[0063] The composite glassy solid was polished into a parallel plane and tested using a UV-Vis-NIR spectrophotometer and a fluorescence spectrometer, respectively. Figure 5 The transmittance spectrum of the transparent luminescent bulk material NaYF4: 18%Yb, 2%Er is shown in the figure. As can be seen from the figure, the material has high transmittance (>80%) in the visible light region (400-700nm), which indicates that the modified rare earth nanoparticles are well dispersed and have no obvious light scattering. Figure 6The image shows a fluorescence spectrum. As can be seen from the image, under 980 nm laser excitation, the material exhibits a strong Er-like fluorescence. 3+ The characteristic emission peaks confirm the successful introduction and maintenance of rare-earth luminescence function.

[0064] Example 2

[0065] A highly transparent upconversion luminescent composite photoresist based on the NaYF4:Yb,Tm system was prepared using a method largely consistent with Example 1, except that the rare-earth nanoparticles used were NaYF4:20%Yb, 1%Tm. The resulting composite photoresist also exhibited high transparency and rapidly cured under 5s UV irradiation. Experimental results showed that this composite system possessed extremely high photosensitivity, enabling not only rapid and precise fabrication of three-dimensional structures but also excellent optical uniformity in the cured product.

[0066] The composite glassy solid obtained by curing the NaYF4:Yb,Tm system was polished into a parallel plane and tested using a UV-Vis-NIR spectrophotometer and a fluorescence spectrometer, respectively.

[0067] Figure 7 The transmittance spectrum of this system shows that the material maintains a transmittance of over 70% in the visible light region (400-800 nm), exhibiting excellent transparency. This confirms that the ligand-exchange modified NaYF4:Yb,Tm nanoparticles achieve atomically highly uniform dispersion in cage-like polysilsesquioxane matrix, effectively suppressing interfacial scattering loss.

[0068] Figure 8 The fluorescence spectrum of this system shows that, under 980 nm laser excitation, the material exhibits strong Tm in the blue band. 3+ Characteristic upconversion emission peaks were observed, with main peaks located at ~450 nm and ~475 nm, respectively. These spectral characteristics confirm that the NaYF4:Yb,Tm nanoparticles maintained complete and efficient luminescence function after curing with the composite photoresist. Furthermore, thanks to the uniform distribution locked by covalent bonding, no significant fluorescence quenching phenomenon caused by particle aggregation was observed.

[0069] Example 3

[0070] A micropatterning method based on spin coating and ultraviolet lithography; the fabrication process can be found in [reference needed]. Figure 9 The specific steps are as follows:

[0071] A301. Spin coat the composite photoresist prepared in Example 1 directly onto a clean glass substrate (or a silicon substrate or other flat substrate) to obtain a uniform and smooth thin film. The spin coating parameters are: 500 rpm / 5s, followed by 1000 rpm / 30s.

[0072] A302. Align the mask with the target pattern (such as micro-lines or dot matrix) with the coated substrate and perform contact exposure using an ultraviolet light source with a main wavelength of 365nm.

[0073] A303. After exposure, the substrate is directly immersed in PGMEA for development. The photoresist in the unexposed areas is dissolved and removed. Then, it is rinsed with isopropanol and dried with nitrogen.

[0074] During the development process, the exposed areas are completely cured through a covalent bond network, exhibiting excellent solvent resistance, while the unexposed areas are completely removed by the developer, thus forming a high-contrast luminescent microstructure on the substrate. The developed pattern is then observed under an optical microscope, as shown... Figure 10 As shown, the edges of the pattern are clear and regular, further confirming that the composite photoresist has excellent morphological fidelity and precise processing resolution during the photolithography process.

[0075] In summary, this invention achieves efficient preparation of high-performance composite photoresists at room temperature and pressure by deeply integrating a liquid bifunctional ligand in-situ exchange method with a specific cage-like polysilsesquioxane composite system. This process fundamentally enhances the interfacial compatibility between nanoparticles and the matrix through a chemical bonding mechanism. While achieving atomic-level dispersion, eliminating interfacial scattering, and endowing the material with high transparency and efficient luminescence properties, it exhibits excellent comprehensive processing performance: thanks to the system's ultra-high photosensitivity, the material can achieve rapid and thorough curing under low-dose UV exposure, greatly improving processing efficiency; simultaneously, the system possesses excellent process compatibility, requiring no cumbersome substrate pretreatment or post-baking processes, and can be adapted to various photocuring techniques to achieve high-resolution patterning; the resulting micron-level patterns have sharp edges, complete structures, and perfectly retain the active luminescence properties of rare-earth units, fully demonstrating the material's enormous potential as a high-performance, multifunctional integrated photonic platform material.

[0076] It should be noted that the composite photoresist system of this invention, due to its extremely low light scattering characteristics, uniform nanoparticle distribution, and excellent photocuring performance, is not limited to the UV curing technology shown in the above embodiments. It will be obvious to those skilled in the art that this material system is also suitable for micro / nano 3D printing processes using the two-photon polymerization principle. In the two-photon polymerization process, a focused femtosecond laser can induce precise curing of the photoresist within the focal volume, thereby directly 'writing' arbitrary three-dimensional micro / nano structures. This invention achieves chemical bonding between nanoparticles and the matrix through ligand exchange, fundamentally ensuring that even in the high-viscosity, solvent-free environment required for two-photon printing, the nanoparticles will not aggregate, thus ensuring that the printed micro / nano structures possess both high transparency and efficient light-emitting properties. Therefore, using the materials of this invention to fabricate three-dimensional micro / nano photonic devices through two-photon polymerization technology should be considered a reasonable and feasible extension of the technical solution provided by this invention.

[0077] In the description of this application, it should be understood that the word 'comprising' does not exclude the presence of elements or steps not listed in the claims. The word 'a' or 'an' preceding an element does not exclude the presence of a plurality of such elements. The simple fact that certain measures are recited in mutually different dependent claims does not suggest that combinations of these measures cannot be used for improvement. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A composite photoresist of highly transparent rare earth nanoparticles and cage-like polysilsesquioxane, characterized in that, The invention comprises a cage-like polysilsesquioxane composite matrix and rare-earth nanoparticles modified with bifunctional ligands; the bifunctional ligands have a first functional group for anchoring on the surface of the rare-earth nanoparticles, and a second functional group that forms a chemical bond with the cage-like polysilsesquioxane composite matrix through photopolymerization; the bifunctional ligands include mono[2-(2-methacryloyloxy)ethyl] succinate; the rare-earth nanoparticles include fluoride, oxide, or vanadate nanocrystals doped with luminescent ions; the luminescent ions include Yb 3+ Er 3+ and Tm 3+ At least one of the following: the cage-like polysilsesquioxane composite matrix comprises cage-like silsesquioxane, prepolymer monomer, and photoinitiator; the mass ratio of cage-like silsesquioxane, prepolymer monomer, and photoinitiator is (90-91):(8-10):(0.4-0.6); the cage-like silsesquioxane comprises acryloyloxypropyl cage-like polysilsesquioxane, the prepolymer monomer comprises multifunctional acrylate, and the photoinitiator comprises phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

2. The highly transparent rare-earth nanoparticles and cage-like polysilsesquioxane composite photoresist according to claim 1, characterized in that, The structure of the succinic acid mono[2-(2-methacryloyloxy)ethyl] ester is as follows: 。 3. The highly transparent rare-earth nanoparticles and cage-like polysilsesquioxane composite photoresist according to claim 1, characterized in that, The rare earth nanoparticles include NaYF4:Yb,Er upconversion luminescent nanoparticles or NaYF4:Yb,Tm upconversion luminescent nanoparticles.

4. A method for preparing a composite photoresist of highly transparent rare-earth nanoparticles and cage-like polysilsesquioxane as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. The rare earth nanoparticles are surface modified using the bifunctional ligand to obtain modified rare earth nanoparticles with polymerizable groups on their surface. S2. The modified rare earth nanoparticles are mixed with the cage-like silsesquioxane, prepolymer monomer and photoinitiator and uniformly dispersed to obtain the composite photoresist.

5. A three-dimensional transparent light-emitting device, characterized in that, It is manufactured using high-transparency rare-earth nanoparticles and cage-like polysilsesquioxane composite photoresist as described in any one of claims 1-3, through photocuring molding technology.

6. The three-dimensional transparent light-emitting device according to claim 5, characterized in that, The three-dimensional transparent light-emitting device includes at least one of optical fibers, optical waveguides, and photonic crystals, or includes an integrated structure composed of at least two of the optical fibers, optical waveguides, and photonic crystals.

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