High-stability polarization holographic optical element and preparation method and application thereof
By introducing NiO or ZnO nanoparticles and siloxane-based surfactants into the orientation layer of the polarized body holographic grating, the problem of restricted orientation shift and dynamic response capabilities of liquid crystal molecules is solved, and the stability and lifetime of polarized holographic optical elements are significantly improved.
Patent Information
- Application Number
- CN202510563967.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-30
- Publication Date
- 2025-06-27
AI Technical Summary
Polarized holographic gratings are prone to liquid crystal molecules orientation deviation, limited dynamic response capability and stability problems in long-term or high temperatures, resulting in reduced device life.
NiO or ZnO nanoparticles with a particle size of 1-10 nm were introduced into the orientation layer, and a high-stability polarization holographic optical element was prepared using siloxane surfactant and toluene as solvents. Nanoparticles capture moving ions in the light-oriented layer, reduce electron transport resistance, accelerate the reorientation of liquid crystal molecules, and enhance the deflection response sensitivity of liquid crystal molecules by enhancing the optical resonance effect.
The deflection response sensitivity and orientation order of liquid crystal molecules are improved, orientation relaxation caused by external disturbances is suppressed, and the performance stability and lifetime of polarized holographic optical elements are significantly improved.
Smart Images
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Figure BDA0005385426020000061
Abstract
Description
Technical Field
[0001] This application relates to the technical field of optical elements, and particularly relates to a highly stable polarization holographic optical element, a preparation method thereof, and an application thereof. Background Art
[0002] Compared with traditional volume gratings, polarization volume holographic gratings (PVGs) have a higher refractive index modulation and a wider response bandwidth, solve the problem of limited FOV of traditional gratings, and are more suitable for the field of near-eye display optical waveguides. PVGs also have polarization sensitivity that traditional gratings lack, ensuring high transmittance at a large field of view angle, and can be customized in small or large sizes according to the application field, expanding the application range of optical waveguide coupling elements. With its excellent large-angle Bragg diffraction characteristics and good polarization response characteristics, PVG technology has made remarkable progress in recent research and development.
[0003] However, PVGs form diffraction gratings through periodically arranged liquid crystal molecules and face the following problems: First, the photo-orientation anchoring energy is insufficient, the orientation stability of liquid crystal molecules on the substrate surface is poor, and they are prone to shift under long-term or high-temperature conditions; second, the dynamic response ability of liquid crystal molecules is limited, affecting the light modulation efficiency; third, there is a stability problem, and changes in environmental temperature and humidity are likely to cause oxidation of the alignment layer, reducing the device life. Summary of the Invention
[0004] To solve the above technical problems, this application provides a highly stable polarization holographic optical element, a preparation method thereof, and an application thereof.
[0005] In a first aspect, this application provides a highly stable polarization holographic optical element, which is prepared from a substrate, an alignment layer, and a liquid crystal layer; The alignment layer is prepared from a dye, nanoparticles, a silicone surfactant, and toluene with a weight ratio of 8.4 - 10.4:0.2 - 0.6:0.08 - 0.20:1000; the nanoparticles are selected from one or more of NiO nanoparticles with a particle size of 1 - 10 nm and ZnO nanoparticles with a particle size of 1 - 10 nm; The liquid crystal layer is prepared from RM257 liquid crystal, a photoinitiator, a chiral agent, a surfactant, and PGMEA with a weight ratio of 12 - 16:1 - 2:0.008 - 0.013:0.01 - 0.03:80 - 86.
[0006] In this application, an alignment layer material is prepared by blending a dye, nanoparticles, a siloxane surfactant, and toluene. NiO nanoparticles or ZnO nanoparticles are introduced into the alignment layer. Utilizing their wide-bandgap semiconductor properties, mobile ions in the photo-alignment layer are captured, reducing the electron transport resistance and accelerating the reorientation of liquid crystal molecules. Meanwhile, the nanoparticles can enhance the local field intensity of incident light by enhancing the optical resonance effect, further improving the deflection response sensitivity of liquid crystal molecules. Moreover, the nanoparticles can bind to the dye through π-π stacking or electrostatic interactions, providing additional anchoring sites and enhancing the liquid crystal alignment order to ensure stability. By precisely controlling the distribution and arrangement of NiO and ZnO nanoparticles in the alignment layer, the orientation of liquid crystal molecules can be guided, thereby enhancing the stability of the pretilt angle. At the same time, this structure can effectively regulate the diffraction behavior of light, not only improving the diffraction efficiency but also maintaining its long-term stability. The introduction of the siloxane surfactant can form a uniform thin film on the surface of the alignment layer, reducing surface defects and further enhancing stability. Meanwhile, the functional groups modified on the surface of the nanoparticles form hydrogen bonds with liquid crystal molecules, optimizing the refractive index of the alignment layer, suppressing the orientation relaxation caused by external perturbations, reducing the scattering loss of light during propagation, and further improving the stability. Using toluene as the solvent of the alignment layer can effectively adjust the compatibility between the dye, nanoparticles, and siloxane surfactant, improve the synergistic effect between raw materials, and thus improve the stability of the performance of the polarization holographic optical element.
[0007] Preferably, the alignment layer is prepared from a dye, nanoparticles, a siloxane surfactant, and toluene with a weight ratio of 9.0 - 9.8:0.3 - 0.5:0.12 - 0.16:1000.
[0008] Preferably, the nanoparticles are composed of a mixture of NiO nanoparticles with a particle size of 1 - 10 nm and ZnO nanoparticles with a particle size of 1 - 10 nm in a weight ratio of 7 - 10:1 - 5.
[0009] In a specific embodiment, the weight ratio between the NiO nanoparticles with a particle size of 1 - 10 nm and the ZnO nanoparticles with a particle size of 1 - 10 nm can be 7:1, 8:1, 9:1, 10:1, 7:3, 8:3, 9:3, 10:3, 7:5, 8:5, 9:5, 10:5.
[0010] Through experimental analysis, it can be known that using NiO nanoparticles with a particle size of 1 - 10 nm and ZnO nanoparticles with a particle size of 1 - 10 nm in the above weight ratio to form the nanoparticles can further improve the performance of the polarization holographic optical element.
[0011] Preferably, the siloxane surfactant is selected from (3-aminopropyl)triethoxysilane surfactant APTES, polyether-modified siloxane surfactant L-77, polyether-modified siloxane surfactant L-7600, sulfonic acid group-modified siloxane surfactant Dow 193, alkyl polyether siloxane surfactant TEGOPREN 7008.
[0012] Preferably, the siloxane surfactant is composed of a polyether-modified siloxane surfactant L-7600 and a sulfonic acid group-modified siloxane surfactant Dow 193 mixed in a weight ratio of 10:0.5 - 3.
[0013] In the design of the siloxane surfactant, the polyether-modified siloxane surfactant L-7600 can reduce the surface tension of the material, improve the wettability, and reduce the defects of the alignment layer; the sulfonic acid group-modified siloxane surfactant can adjust the interfacial charge distribution, balance the charges, promote the directional arrangement of liquid crystal molecules, and enhance the stability of the alignment layer. Through multiple experiments, the applicant found that using the polyether-modified siloxane surfactant L-7600 and the sulfonic acid group-modified siloxane surfactant Dow 193 mixed to form a surfactant can further improve the stability of the polarization holographic optical element.
[0014] Preferably, the dye is selected from one or more of BY, SD1, and PI.
[0015] Preferably, in the liquid crystal layer, the surfactant is selected from one or more of fluorine-based surfactants and siloxane surfactants.
[0016] Preferably, in the liquid crystal layer, the photoinitiator is TPO and the chiral agent is R5011 / S5011.
[0017] In a second aspect, the present application provides a method for preparing the above high-stability polarization holographic optical element, which specifically includes the following steps in sequence: Under light-shielded conditions, weigh the corresponding weight ratios of the dye, nanoparticles, siloxane surfactant, and toluene, mix them, and use ultrasonic dispersion to make them uniform to obtain an alignment layer solution; Under light-shielded conditions, weigh the corresponding weight ratios of liquid crystal, photoinitiator, chiral agent, surfactant, and PGMEA, mix them evenly, and the solution after suction filtration is the liquid crystal layer solution; Apply the alignment layer solution onto a substrate and expose it using a laser; spin-coat the liquid crystal layer solution onto the exposed substrate and perform ultraviolet curing in a nitrogen environment to obtain a highly stable polarization holographic optical element.
[0018] In a second aspect, the present application provides the use of the above-mentioned highly stable polarization holographic optical element in image display or projection.
[0019] In summary, the technical solution of the present application has the following effects: By introducing NiO nanoparticles or ZnO nanoparticles and a siloxane surfactant into the alignment layer, and using toluene as a solvent, the pretilt angle, diffraction efficiency, and stability of the polarization holographic optical element prepared are relatively good; the deflection response sensitivity of liquid crystal molecules is improved by the technical solution provided by the present application, the alignment order of liquid crystals is enhanced, the alignment relaxation caused by external disturbances is inhibited, and the performance stability of the polarization holographic optical element is effectively improved. Specific Embodiments
[0020] The present application will be further described in detail below with reference to examples, comparative examples, and performance detection tests. These examples should not be construed as limiting the scope claimed by the present application.
[0021] The NiO nanoparticles and ZnO nanoparticles used in the present application are sourced from pixelligent. Examples
[0022] Examples 1 - 5 Examples 1 - 5 respectively provide a highly stable polarization holographic optical element and a preparation method thereof.
[0023] The difference between the above examples lies in: the dosage ratio between the raw materials in the alignment layer is different, as shown in Table 1 specifically.
[0024] The preparation method of the highly stable polarization holographic optical element in the above examples is as follows: Preparation of the alignment layer solution: Under light-shielded conditions, weigh the corresponding weight ratios of the dye azobenzene derivative SD1, nanoparticles (composed of NiO nanoparticles with a particle size of 1 - 10 nm and ZnO nanoparticles with a particle size of 1 - 10 nm in a weight ratio of 8:3), a siloxane surfactant (composed of a polyether-modified siloxane surfactant L-7600 and a sulfonic acid group-modified siloxane surfactant Dow 193 in a weight ratio of 10:1), and toluene, and disperse them using a 1000w ultrasonic wave at 60 °C for 2h to obtain the alignment layer solution.
[0025] Preparation of liquid crystal layer solution: Under light-shielded conditions, weigh RM257 liquid crystal, photoinitiator, chiral agent, polyoxyethylene fluorinated alcohol Zonyl FSN-100 surfactant, and PGMEA in a ratio of 14:1:0.01:0.02:83, mix them, and after 30 minutes, perform suction filtration using a PTFE sieve with a pore size of 0.2 microns. Subsequently, seal the obtained solution with tin foil and store it at room temperature.
[0026] Setup of holographic exposure optical path: Apply 2 ml of alignment layer solution onto a 6 cm × 6 cm ITO glass substrate. The laser emitted by a 365 nm ultraviolet or 450 nm blue laser passes through a mirror (beam expander system + 15-micron aperture to expand the laser beam and then pass it through a small hole filter to eliminate stray light and improve beam quality; PBS selects linearly polarized light to ensure the same polarization direction; collimating lens adjusts the beam into parallel light to ensure the uniformity of the exposure area), and the laser is directed onto the substrate coated with the alignment dye solution to achieve holographic recording and obtain the exposed substrate.
[0027] Preparation of polarization holographic optical element: Place the exposed substrate on a spin coater with a vacuum chuck, use a rotation speed of 6000 rpm, and uniformly drop and spin coat 7 ml of high-refractive-index liquid crystal layer solution onto the exposed substrate to form a grating. Subsequently, in a nitrogen environment, cure it with 365 nm ultraviolet light at 20 mW / cm 2 to obtain a polarization holographic optical element.
[0028] Table 1 Dosage ratio between raw materials in the alignment layer in Examples 1-5 Examples 6-9 Examples 6-9 respectively provide a highly stable polarization holographic optical element and its preparation method.
[0029] The differences between the above examples and Example 3 are as follows: The types of nanoparticles in the alignment layer are different, as specifically shown below.
[0030] In Example 6: The nanoparticles are NiO nanoparticles.
[0031] In Example 7: The nanoparticles are composed of a mixture of NiO nanoparticles with a particle size of 1-10 nm and ZnO nanoparticles with a particle size of 1-10 nm in a weight ratio of 3:8.
[0032] In Example 8: The nanoparticles are composed of a mixture of NiO nanoparticles with a particle size of 1-10 nm and ZnO nanoparticles with a particle size of 1-10 nm in a weight ratio of 7:5.
[0033] In Example 9: The nanoparticles are composed of a mixture of NiO nanoparticles with a particle size of 1-10 nm and ZnO nanoparticles with a particle size of 1-10 nm at a weight ratio of 10:1.
[0034] In the above examples, other process parameters are the same as those in Example 3.
[0035] Examples 10-13 Examples 10-13 respectively provide a highly stable polarization holographic optical element and a preparation method thereof.
[0036] The difference between the above examples and Example 3 is that: the types of siloxane surfactants in the alignment layer are different, as shown below.
[0037] In Example 10: The siloxane surfactant is composed of a mixture of a polyether-modified siloxane surfactant L-77 and an alkyl polyether siloxane surfactant TEGOPREN 7008 at a weight ratio of 10:1.
[0038] In Example 11: The siloxane surfactant is composed of a mixture of a polyether-modified siloxane surfactant L-7600 and a sulfonic acid group-modified siloxane surfactant Dow 193 at a weight ratio of 1:10.
[0039] In Example 12: The siloxane surfactant is composed of a mixture of a polyether-modified siloxane surfactant L-7600 and a sulfonic acid group-modified siloxane surfactant Dow 193 at a weight ratio of 10:0.5.
[0040] In Example 13: The siloxane surfactant is composed of a mixture of a polyether-modified siloxane surfactant L-7600 and a sulfonic acid group-modified siloxane surfactant Dow 193 at a weight ratio of 10:3.
[0041] In the above examples, other process parameters are the same as those in Example 3.
[0042] Comparative examples Comparative examples 1-5 Comparative examples 1-5 respectively provide a highly stable polarization holographic optical element and a preparation method thereof.
[0043] The difference between the above comparative examples and Example 3 is as shown below.
[0044] In Comparative Example 1: In the alignment layer, no nanoparticles are added.
[0045] In Comparative Example 2: In the alignment layer, the nanoparticles are composed of a mixture of TiO₂ nanoparticles with a particle size of 1 - 10 nm and ZnO nanoparticles with a particle size of 1 - 10 nm at a weight ratio of 8:3.
[0046] In Comparative Example 3: In the alignment layer, an equal amount of DMF is used to replace toluene as the solvent.
[0047] In Comparative Example 4: In the alignment layer, an equal amount of polyoxyethylene fluorinated alcohol Zonyl FSN - 100 is used to replace the silicone surfactant as the surfactant.
[0048] In Comparative Example 5: The weight ratio of the dye, nanoparticles, silicone surfactant, and toluene is 9.4:0.1:0.3:10000.
[0049] Other process parameters in the above comparative examples are the same as those in Example 3.
[0050] Performance detection test (1) Pretilt angle and its stability: The pretilt angle of the polarization holographic optical element is detected by a polarization microscope. Then, the optical element is operated under high temperature of 85 °C and high humidity of 85% RH for 500 hours, and the change value of the pretilt angle of the polarization holographic optical element after aging is detected.
[0051] (2) Diffraction efficiency and its stability: A monochromatic laser of 633 nm is vertically incident on the device to detect the diffraction efficiency of the polarization holographic optical element. Then, the optical element is operated under high temperature of 85 °C and high humidity of 85% RH for 500 hours, and the diffraction efficiency of the polarization holographic optical element after aging is detected to investigate its aging resistance.
[0052] The detection results are shown in Table 2.
[0053] Table 2 Performance detection results of the polarization holographic optical elements in the examples and comparative examples Combined with the performance detection results of the polarization holographic optical elements in the above table, it can be seen that in this application, by introducing NiO nanoparticles or ZnO nanoparticles and silicone surfactants into the alignment layer, and using toluene as the solvent at the same time, the prepared polarization holographic optical element has a pretilt angle of 6 - 9° and a diffraction efficiency as high as 94.5% - 99.1%; and after the aging test, the pretilt angle and diffraction efficiency of the polarization holographic optical element have good stability. The above detection results show that the technical solution of this application improves the deflection response sensitivity of liquid crystal molecules, enhances the liquid crystal alignment order, suppresses the orientation relaxation caused by external disturbances, and effectively improves the performance stability of the polarization holographic optical element.
[0054] In Comparative Example 1, no nanoparticles were added to the alignment layer. In Comparative Example 2, the nanoparticles in the alignment layer were composed of a mixture of TiO2 nanoparticles with a particle size of 1-10 nm and ZnO nanoparticles with a particle size of 1-10 nm at a weight ratio of 8:3. In Comparative Example 3, an equal amount of DMF was used to replace toluene as the solvent in the alignment layer. In Comparative Example 4, an equal amount of polyoxyethylene fluorinated alcohol Zonyl FSN-100 was used to replace the silicone surfactant as the surfactant in the alignment layer. In Comparative Example 5, the weight ratio of the dye, nanoparticles, silicone surfactant, and toluene was 9.4:0.1:0.3:10000, and the pretilt angle, diffraction efficiency, and stability of the prepared holographic optical element were poor.
[0055] In contrast, in Examples 1-5 of the present application, by controlling the dosage ratio between the raw materials (dye, nanoparticles, silicone surfactant, toluene) in the alignment layer, in Examples 6-9, by introducing NiO nanoparticles or ZnO nanoparticles into the alignment layer, and in Examples 10-13, by introducing silicone surfactant into the alignment layer, the performance of the polarization holographic optical element can be effectively improved.
[0056] Although the present invention has been described in detail above with general descriptions and specific embodiments, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of the present invention claimed.
Claims
1. A high-stability polarization holographic optical element, characterized in that: It is prepared from a substrate, an orientation layer, and a liquid crystal layer; The alignment layer is prepared from dye, nanoparticles, siloxane surfactant, and toluene in a weight ratio of 8.4-10.4:0.2-0.6:0.08-0.20:1000; the nanoparticles are selected from one or more of NiO nanoparticles with a particle size of 1-10 nm and ZnO nanoparticles with a particle size of 1-10 nm; The liquid crystal layer is prepared from RM257 liquid crystal, photoinitiator, chiral agent, surfactant and PGMEA in a weight ratio of 12-16: 1-2: 0.008-0.013: 0.01-0.03: 80-86.
2. The high stability polarization holographic optical element according to claim 1, characterized in that: The alignment layer is prepared from dye, nanoparticles, siloxane surfactant and toluene in a weight ratio of 9.0-9.8:0.3-0.5:0.12-0.16:1000.
3. The high stability polarization holographic optical element according to claim 1, characterized in that: The nanoparticles are composed of a mixture of NiO nanoparticles with a particle size of 1-10 nm and ZnO nanoparticles with a particle size of 1-10 nm in a weight ratio of 7-10:1-5.
4. The high stability polarization holographic optical element according to claim 1, characterized in that: The silicone surfactant is selected from (3-aminopropyl) triethoxysilane surfactant APTES, polyether modified silicone surfactant Silwet® L-77, polyether modified silicone surfactant Silwet® L-7600, sulfonic acid modified silicone surfactant Dow Corning® 193, and alkyl polyether silicone surfactant TEGOPREN 7008.
5. The high-stability polarization holographic optical element according to claim 4, characterized in that: The silicone surfactant is composed of a mixture of a polyether-modified silicone surfactant L-7600 and a sulfonic acid-modified silicone surfactant Dow Corning® 193 in a weight ratio of 10:0.5-3.
6. The high-stability polarization holographic optical element according to claim 1, characterized in that: The dye is selected from one or more of BY, SD1, and PI.
7. The high stability polarization holographic optical element according to claim 1, characterized in that: In the liquid crystal layer, the surfactant is selected from one or more of a fluorine-based surfactant and a silicone-based surfactant.
8. The high-stability polarization holographic optical element according to claim 1, characterized in that: In the liquid crystal layer, the photoinitiator is TPO, and the chiral agent is R5011 / S5011.
9. A method for preparing a high-stability polarization holographic optical element according to any one of claims 1 to 8, characterized in that: Specifically, the following steps are performed in sequence: Under light-proof conditions, weigh the dye, nanoparticles, siloxane surfactant, and toluene in corresponding weight ratios, mix them, and disperse them evenly using ultrasound to obtain an alignment layer solution; Under light-proof conditions, weigh the corresponding weight ratio of liquid crystal, photoinitiator, chiral agent, surfactant, and PGMEA and mix them evenly. The solution after suction filtration is the liquid crystal layer solution; Applying the alignment layer solution onto a substrate and exposing it using a laser; The liquid crystal layer solution is spin-coated onto the exposed substrate, and ultraviolet curing is performed in a nitrogen environment to obtain a highly stable polarization holographic optical element.
10. Use of the high-stability polarization holographic optical element according to any one of claims 1 to 8 in image display or projection.