Transmission structure color device based on nanostructure cavity and preparation method thereof

Abstract

The invention provides a transmission structure color device based on a nanostructure cavity. The transmission structure color device is composed of a substrate layer, the nanostructure cavity and a top high-refractive-index dielectric layer. The nanostructure cavity is composed of a lower metal layer, an upper metal layer and a low-refractive-index intermediate dielectric layer comprising a high-refractive-index dielectric square array. The thickness h2 of the lower metal layer is 25 nm, the thickness h3 of the upper metal layer is 25-55 nm, the thickness h4 of the high-refractive-index dielectric square array is 192 nm, the thickness h5 of the low-refractive-index intermediate dielectric layer is 240 nm, the thickness h6 of the top high-refractive-index dielectric layer 6 is 50 nm, the width w of the high-refractive-index dielectric square array is 30-150 nm, and the period P is 160 nm. Under the condition that the thickness of the upper metal layer is kept unchanged, transmission colors which are insensitive in angle, high in saturation degree and large in color gamut coverage range can be obtained only by adjusting the width of the high-refractive-index dielectric square array.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of micro-nano optics, in particular to a transmission structural color device based on nano-structured cavity and a preparation method thereof. BACKGROUND

[0002] Biomimetic structural colors based on metallic surfaces are considered to have high-quality full-color display, high-angle tolerance, flexible polarization control and low loss, which are crucial for optical devices in advanced information encryption, display and filtering technologies. Due to the excellent performance of structural color, the color characteristics (such as hue, saturation and brightness) of structural color devices (especially, structural color devices based on Fabry-Perot resonant cavity (F-P cavity)) have been widely studied.

[0003] At present, the deficiencies of structural color devices based on F-P cavity mainly focus on two aspects: 1) structural color devices based on F-P cavity cannot simultaneously achieve good angle insensitivity and coverage of wide color gamut range, that is, there is always a trade-off between angle insensitivity and color gamut range; 2) traditional structural color devices based on F-P cavity are adjusted by adjusting the thickness of the intermediate medium layer to control the color, which is not conducive to the realization of monolithic integrated full-color display. Therefore, if the structural color devices based on F-P cavity can simultaneously achieve good angle insensitivity and coverage of wide color gamut range, and also meet the demand of monolithic integrated full-color display, it will promote the application of structural color devices based on F-P cavity in advanced display fields such as photography and dynamic color display. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a transmission structural color device based on nano-structured cavity, which can realize angle-insensitive, wide color gamut, high-saturation transmission structural color, and also has the characteristics of adjustable color brightness and monolithic integration.

[0005] Technical scheme of the present application:

[0006] A transmission structural color device based on nano-structured cavity, which is stacked from bottom to top by a substrate layer, a nano-structured cavity and a top high-refractive-index medium layer; the nano-structured cavity is composed of a lower metal layer, an upper metal layer, a high-refractive-index medium square array and a low-refractive-index intermediate medium layer; the high-refractive-index medium square array is embedded in the low-refractive-index intermediate medium layer to form a nano-structured intermediate layer.

[0007] Further, the material of the substrate layer is silicon dioxide, the materials of the upper metal layer and the lower metal layer are silver, the thickness h2 of the lower metal layer is 25 nm, and the thickness h3 of the upper metal layer ranges from 25 nm to 55 nm. By increasing the thickness of the upper metal layer, part of the light is absorbed and reflected, so as to adjust the brightness of the transmission color.

[0008] Further, the material of the high refractive index medium square array is one of titanium dioxide or zinc sulfide, and the thickness h4 thereof is 192 nm, the period P of the high refractive index medium square array is 160 nm, and the width w of the high refractive index medium square array is 30-150 nm; the material of the low refractive index intermediate medium layer is one of dimethyl polysiloxane, polyvinyl alcohol, and polyimide, and the thickness h5 thereof is 240 nm. Embedding the high refractive index medium square array with different widths in the low refractive index intermediate medium layer can regulate the equivalent refractive index of the nanostructure intermediate layer, thereby realizing a monolithic integrated full-color structural color device.

[0009] Further, the material of the top layer high refractive index medium layer is one of titanium dioxide or zinc sulfide, and the thickness h6 thereof is 50 nm. The top layer high refractive index medium layer functions as an antireflection layer in the device.

[0010] In the above technical solution, embedding the high refractive index medium square array at any position in the low refractive index intermediate medium layer does not affect the regulation of the equivalent refractive index of the nanostructure intermediate layer of the nanostructure cavity; under this premise, regulating the width of the high refractive index medium square array can still realize a monolithic integrated full-color structural color device.

[0011] The technical solution of the present application also includes a manufacturing method of a transmission structural color device based on a nanostructure cavity, comprising the following steps:

[0012] Step 1: using an electron beam evaporation technology to deposit a 25 nm thick silver layer on a substrate layer with a material of silicon dioxide, and the silver layer is a lower metal layer;

[0013] Step 2: rotating and coating one of dimethyl polysiloxane, polyvinyl alcohol, and polyimide on the upper side of the lower metal layer and curing to form a low refractive index film layer, and then etching the low refractive index film layer to a thickness of 24 nm by a reactive ion etching;

[0014] Step 3: depositing a high refractive index lossless medium layer with a thickness of 192 nm and a material of one of titanium dioxide or zinc sulfide on the low refractive index intermediate medium layer in step 2 by a plasma enhanced chemical vapor deposition method;

[0015] Step 4: rotating and coating an electron beam resist film on the high refractive index lossless medium layer and drying to form an electron beam resist layer, and making a square array on the electron beam resist layer;

[0016] Step 5: focusing ion etching the square array to obtain a high refractive index medium square array;

[0017] Step 6: spin-coat one of dimethyl polysiloxane, polyvinyl alcohol, and polyimide on the high-refractive-index medium square array and solidify to form a thin film layer, etch the low-refractive-index thin film layer to a thickness of 24 nm by reactive ion etching, and finally form a low-refractive-index intermediate medium layer with a thickness of 240 nm wrapping the high-refractive-index medium square array;

[0018] Step 7: deposit an upper metal layer with a material of silver on the low-refractive-index intermediate medium layer by electron beam evaporation technology, and deposit a top layer high-refractive-index medium layer with a thickness of 50 nm and a material of one of titanium dioxide and zinc sulfide on the upper metal layer by plasma-enhanced chemical vapor deposition.

[0019] Compared with the prior art, the application has the following advantages and positive effects:

[0020] 1. The application adopts a nano-structured cavity structure, and various transmission colors can be integrated on the same cavity length and the same substrate. By controlling the width of the high-refractive-index medium square array, the refractive index of the nano-structured intermediate layer of the nano-structured cavity can be controlled, that is, the transmission color can be controlled in a wide range by controlling the refractive index of the intermediate medium layer in the F-P cavity, and the transmission color covers about 130% of the sRGB color gamut space and about 90% of the Adobe sRGB color gamut space.

[0021] 2. Based on the cavity resonance effect, the field of view of the transmission color display of the application is not less than 25°; by controlling the thickness of the upper metal layer, the application can also provide customized brightness for the transmission color to meet the application requirements. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structural schematic diagram of a transmission structural color device based on a nano-structured cavity;

[0023] Figure 2 is the transmission spectrum and color characteristics of the application under different widths of the high-refractive-index medium square array;

[0024] Figure 3 is the angle-insensitive characteristics of the application under different widths of the high-refractive-index medium square array;

[0025] Figure 4 is the transmission spectrum and color characteristics of the application under different thicknesses of the upper metal layer;

[0026] Figure 5 is a cross-sectional schematic diagram of a transmission structural color device based on a nano-structured cavity; DETAILED DESCRIPTION

[0027] The application will be further described in detail below in combination with the drawings and examples, but the examples are not used to limit the application, and any similar structure and similar changes thereof shall be included in the protection scope of the application.

[0028] The application includes a transmission structural color device based on nano-structured cavity. The specific parameters of the embodiment are as follows: the application is stacked from bottom to top by a substrate layer 1 with a material of silicon dioxide, a nano-structured cavity, and a top layer of high refractive index medium layer 6 with a thickness h6 of 50 nm and a material of titanium dioxide, as shown in the figure. Figure 1 The nano-structured cavity is composed of a lower metal layer 2 with a thickness h2 of 25 nm and a material of silver, an upper metal layer 3 with a suitable thickness and a material of silver, a high refractive index medium square array 4 with a thickness h4 of 192 nm and a material of one of titanium dioxide or zinc sulfide, and a low refractive index medium layer 5 with a thickness h5 of 240 nm and a material of one of dimethyl polysiloxane, polyvinyl alcohol, and polyimide. Among them, the high refractive index medium square array 4 is selected to be embedded in the low refractive index medium layer 5 to form a nano-structured intermediate layer. In the above, the thickness h3 of the upper metal layer 3 ranges from 25 nm to 55 nm, the width w of the high refractive index medium square array 4 ranges from 30 nm to 150 nm, and the period P of the high refractive index medium square array 4 is 160 nm.

[0029] The specific steps of the preparation method of the transmission structural color device based on the nano-structured cavity of the application are as follows:

[0030] Step 1: A 25 nm thick silver layer is deposited on the substrate layer 1 with a material of silicon dioxide by using electron beam evaporation technology, and the silver layer is the lower metal layer 2.

[0031] Step 2: One of dimethyl polysiloxane, polyvinyl alcohol, and polyimide is spin-coated on the upper side of the lower metal layer 2 and cured to form a low refractive index film layer, and then the film layer is etched to a thickness of 24 nm by reactive ion etching;

[0032] Step 3: A high refractive index lossless medium layer with a thickness of 192 nm and a material of one of titanium dioxide or zinc sulfide is deposited on the low refractive index film layer in step 2 by plasma enhanced chemical vapor deposition method;

[0033] Step 4: An electron beam resist film is spin-coated on the high refractive index lossless medium layer and dried to form an electron beam resist layer, and a square array is made on the electron beam resist layer;

[0034] Step 5: The square array in step 4 is focused ion etched to obtain a high refractive index medium square array 4;

[0035] Step 6: spin-coat one of dimethylpolysiloxane, polyvinyl alcohol, and polyimide on the high-refractive-index medium square array 4 and cure it to form a low-refractive-index thin film layer, and etch the low-refractive-index thin film layer to 24 nm by reactive ion etching; finally, form a low-refractive-index intermediate medium layer 5 with a thickness of 240 nm wrapping the high-refractive-index medium square array 4;

[0036] Step 7: deposit an upper metal layer 3 with a material of silver on the low-refractive-index intermediate medium layer 5 by electron beam evaporation technology, and deposit a top layer high-refractive-index medium layer 6 with a thickness of 50 nm and a material of one of titanium dioxide and zinc sulfide on the upper metal layer 3 by plasma-enhanced chemical vapor deposition.

[0037] Thus, the structure of the transmissive structural color device is obtained as shown in Figure 1 .

[0038] Figure 2 is the transmittance spectrum and color characteristics of the present application under different widths of the high-refractive-index medium square array 4. At this time, the thickness of the upper metal layer 3 is 25 nm. As shown in Figure 2 (a), with the width of the high-refractive-index medium square array 4 increasing from 30 nm to 150 nm, the main transmittance peak (Wavelength) of the transmittance spectrum red-shifts from 441 nm to 618 nm. At the same time, the efficiency (Transmittance) of the main transmittance peak of the present application under different widths of the high-refractive-index medium square array 4 can be maintained above 70%, and the full width at half maximum (FWHM) of the main transmittance peak can be maintained below 30 nm, as shown in Figure 2 (b). The color gamut corresponding to the transmittance spectrum of the present application under different widths of the high-refractive-index medium square array 4 can achieve coverage of about 130% of the sRGB color gamut range and 90% of the Adobe sRGB color gamut range, as shown in

[0039] Figure 3 is the angle insensitivity characteristics of the present application under different widths of the high-refractive-index medium square array 4. At this time, the thickness of the upper metal layer 3 is 25 nm. Obviously, the transmittance spectrum of the transmissive structural color device with different widths of the high-refractive-index medium square array 4 under different incident angles (Incident angle). From Figure 3It can also be found that the peak transmittance (T) and resonance wavelength of the transmissive structural color device with the high refractive index medium square array 4 of different width remain basically unchanged in the incident angle range of 0°-25°. Specifically, the peak transmittance and relative resonance wavelength shift of the transmissive structural color device with the high refractive index medium square array 4 of different width are less than 1.4% and 1.6%, respectively. The above facts demonstrate that the proposed transmissive structural color device can achieve a wide viewing angle of up to 25°.

[0040] In addition to realizing the angle-insensitive high-quality transmissive color (i.e., the regulation of color hue), the present application also proposes a color brightness adjustable scheme, as shown in Figure 4 Here, the transmissive structural color device with the high refractive index medium square array 4 of a width of 100 nm is taken as an example to study its transmittance spectrum and color characteristics under different thicknesses of the upper metal layer 3. Obviously, with the thickness of the upper metal layer 3 increasing from 25 nm to 55 nm, the resonance wavelength (Wavelength) of the transmissive structural color device with the high refractive index medium square array 4 of a width of 100 nm remains basically unchanged, but its peak transmittance gradually decreases. Corresponding to the change of the transmittance spectrum, the hue and saturation of the transmissive color basically do not change, but the brightness of the transmissive color gradually decreases. That is, by only changing the thickness of the upper metal layer 3, a full-color display with customized brightness can be obtained.

[0041] It is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0042] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be properly combined to form other embodiments that those skilled in the art can understand.

Claims

1. A nanostructured cavity-based transmissive structural color device, characterized in that: It is stacked from bottom to top by the base layer, nano-structured cavity and top layer high refractive index medium layer; the nano-structured cavity is composed of lower metal layer, upper metal layer, high refractive index medium square array and low refractive index intermediate medium layer; the high refractive index medium square array is embedded in the low refractive index intermediate medium layer to form a nano-structured intermediate layer.

2. The nanostructured cavity-based transmissive structural color device of claim 1, wherein: The material of the base layer is silicon dioxide.

3. The nanostructured cavity-based transmissive structural color device of claim 1, wherein: The material of the upper metal layer and the lower metal layer is silver.

4. The nanostructured cavity-based transmissive structural color device of claim 1, wherein: The material of the high refractive index medium square array and the top layer high refractive index medium layer is one of titanium dioxide or zinc sulfide.

5. The nanostructured cavity-based transmissive structural color device of claim 1, wherein: The material of the low refractive index intermediate medium layer is one of dimethyl polysiloxane, polyvinyl alcohol, polyimide.

6. The nanostructured cavity-based transmissive structural color device of claim 1, wherein: The thickness h2 of the lower metal layer is 25 nm; the thickness h3 of the upper metal layer ranges from 25 nm to 55 nm.

7. The nanostructured cavity-based transmissive structural color device of claim 1, wherein: The thickness h4 of the high refractive index medium square array is 192 nm, the width w of the high refractive index medium square array is 30-150 nm, and the period P of the high refractive index medium square array is 160 nm.

8. The nanostructured cavity-based transmissive structural color device of claim 1, wherein: The thickness h5 of the low refractive index intermediate medium layer is 240 nm.

9. The nanostructured cavity-based transmissive structural color device of claim 1, wherein: The thickness h6 of the top layer high refractive index medium layer is 50 nm.

10. A method for manufacturing a nano-structured cavity-based transmission structural color device according to any one of claims 1-9, comprising the following steps: Step 1: using electron beam evaporation technology to deposit a 25 nm thick silver layer on a base layer of material silicon dioxide, the silver layer being a lower metal layer; Step 2: spin coating one of dimethyl polysiloxane, polyvinyl alcohol, polyimide on top of the lower metal layer and curing to form a low refractive index film layer, and then etching the low refractive index film layer to a thickness of 24 nm by reactive ion etching; Step 3: depositing a layer of one of titanium dioxide or zinc sulfide with a thickness of 192 nm on the low refractive index film layer in step 2 by plasma enhanced chemical vapor deposition to form a high refractive index lossless medium layer; Step 4: spin coating an electron beam resist film on the high refractive index lossless medium layer and drying to form an electron beam resist layer, and making a square array on the electron beam resist layer; Step 5: focusing ion etching the square array to obtain a high refractive index medium square array; Step 6: spin coating one of dimethyl polysiloxane, polyvinyl alcohol, polyimide on the high refractive index medium square array and curing to form a low refractive index film layer, and then etching the low refractive index film layer to 24 nm by reactive ion etching, finally forming a low refractive index intermediate medium layer with a thickness of 240 nm wrapping the high refractive index medium square array; Step 7: using electron beam evaporation technology to deposit an upper metal layer of material silver on the low refractive index intermediate medium layer, and depositing a layer of one of titanium dioxide or zinc sulfide with a thickness of 50 nm on the upper metal layer by plasma enhanced chemical vapor deposition to form a top layer high refractive index medium layer.

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