CN100380139C - Biological template method for preparing anti-reflection film - Google Patents

Abstract

The invention provides a method for preparing an anti-reflection film through two-stage replication using the biological nanostructure existing in nature as a template. The biological templates used include anti-reflection photonic crystals on the surface of insect compound eyes and wings. First, the biological nanostructure is used as a template to vacuum-deposit metal, and the negative structure corresponding to the biological template is obtained on the metal film; The structure is template-cast organic polymer, and after solidification, an organic polymer film with a nanostructure consistent with the biological template is obtained on the surface. The anti-reflection film preparation technology of the present invention has simple process, low cost and high yield, and can realize the preparation of large-area nanostructures. The prepared organic polymer film with surface nanostructures has a strong anti-reflection effect and has been successfully It imitates the anti-reflection function of nanostructures on the biological surface, and has a wide range of applications in optics.

Description

Biological template method for preparing anti-reflection film

technical field

The invention relates to a new nanostructure preparation technology, in particular to a method for preparing an anti-reflection structure by copying a biological structure as a template, and belongs to the field of nanomaterial preparation.

Background technique

There are micro-nano structures on the surface of many organisms in nature. These structures have special biological functions after long-term evolution of biological populations in nature, and are closely related to their survival (Pete Vukusic and J.Roy Sambles, nature 424 (2003) 852-855). For example, the compound eyes and wing surfaces of some insects have conical array nanostructures arranged in a regular hexagon, also known as photonic crystals, as shown in Figure 1. The diameter is 150nm, the top diameter is 65nm, the height is about 400nm, arranged in a regular hexagon, and the center distance is 190nm. Studies have shown that this surface conical array nanostructure has a strong anti-reflection function in the ultraviolet and visible light bands, thereby reducing the identification of enemies. The reason why the conical array nanostructures on the surface of cicada wings have anti-reflection function is that the equivalent medium (J.Opt.Soc.Am.A, 8 (1991) 549, J. . Opt. Soc. Am. A, 12(1995) 333).

Anti-reflection has a wide range of applications in optics, for example, it can be used for surface treatment of lenses, rearview mirrors, displays, solar cells, photosensitive sensors and other devices to reduce the reflection of light on the surface and enhance the transmission or absorption of light waves . Although the method of thin-film interference is widely used to reduce the reflection of light waves on the surface, the shortcomings of adhesion and thermal expansion coefficient mismatch between the films seriously affect the stability and durability of its anti-reflection effect. In contrast, it is a good choice to use the conical array structure to perform anti-reflection treatment on the surface. Photolithography, electron beam etching, focused ion beam etching, reactive ion etching, and nanoimprint nanostructure processing techniques have been used to prepare anti-reflective surfaces, but due to the relatively expensive equipment and complicated processes used in these techniques, it is difficult to Meet the requirements of low cost and mass production.

Contents of the invention

The object of the present invention is to provide an anti-reflection film preparation technology, which directly uses the biological nano-structure existing in nature as a template, and prepares an anti-reflection film with a nano-structure by a replication method.

The present invention is achieved through the following technical solutions.

The process steps of preparing anti-reflection film by biological template method are as follows: first, a metal film is vacuum-deposited with a biological nanostructure as a template, and a negative structure corresponding to the biological nanostructure is obtained on the metal film; The template casts the organic polymer, and after curing, an organic polymer antireflection film with a nanostructure consistent with the biological template is obtained on the surface.

Wherein, the biological nanostructures used exist on the surfaces of many organisms, such as the compound eyes and wing surfaces of some insects, and the preferred biological nanostructures include photonic crystals on the compound eyes of moths and cicada wings. When using metal as a material for first-level replication, a metal film with a thickness of 300-500 nm is usually vacuum-deposited on the biological template, and then the metal film is peeled off with an organic polymer glue to obtain a structure corresponding to the biological surface. The negative metal structure is shown in Figure 3. When using organic polymers as materials for secondary replication, the negative metal structure obtained by primary replication is used as a template, and organic polymers are cast on the surface, and cured by heating or ultraviolet radiation, and finally from the metal template. The organic polymer film is peeled off to obtain the desired antireflection film. As shown in FIG. 4 , through the above-mentioned two-stage replication, a nanostructure consistent with the biological template can be obtained on the surface of the organic polymer film, and the precise replication of the nanostructure on the biological surface can be realized.

According to the situation of the biological template, the nanostructure preparation technology of the present invention can be used to realize the preparation of large-scale nanostructures. Metal materials used ⁱⁿ the present invention include gold (Au), chromium (Cr), titanium (Ti), nickel (Ni) and aluminum (Al) and other metals and their alloy materials with certain strength and hardness; The metal is evaporated under certain conditions, and the evaporation rate is 0.15-0.50nm/s. The organic polymer used in the present invention includes polymethyl methacrylate (polymethyl methacrylate, PMMA) and polyurethane (polyurethane, PU) and other organic polymers with relatively high elastic modulus (>1.2Gpa). The curing condition of PMMA is baking at 90-170°C for 30-60 minutes, and the curing condition of PU is irradiating with 8w ultraviolet lamp for 15 minutes-30 minutes.

The nanostructure anti-reflection film preparation technology of the present invention directly uses the photonic crystal on the biological surface as a template, and realizes the precise replication of the nanostructure on the biological surface through the method of secondary replication, avoiding photolithography, electron beam etching, and focused ion Complex traditional nanostructure processing techniques such as beam etching and reactive ion etching provide a simple, low-cost, and high-yield antireflection film preparation technology. Among them, the material used in the first-level replication is a commonly used metal material, which is cheap and easy to obtain, and can be used repeatedly as a template for the second-level replication, which can further reduce the process cost; the curing conditions of the second-level replication are mild, and no external pressure is required. Short curing time, suitable for mass production. The technology of the invention can be used to realize the preparation of large-area nanostructures.

Ultraviolet-visible (UV-Vis) optical characterization shows that in the ultraviolet-visible band, the organic polymer film with surface nanostructure prepared by the present invention has a strong anti-reflection effect, and its reflectivity to ultraviolet-visible light is only About 1/3 of the unstructured organic polymer film has successfully imitated the anti-reflection function of the biological surface nanostructure, and has a wide range of applications in optics, for example, it can be used in lenses, rearview mirrors, displays, solar cells, photosensitive Surface treatment of sensors and other devices to reduce the reflection of light on the surface and enhance the transmission or absorption of light waves.

Description of drawings

Figure 1 is an electron micrograph of the nanostructure on the surface of a cicada wing.

Fig. 2 is a process flow chart of preparing nanostructure anti-reflection film by biological template method of the present invention.

Fig. 3 is an electron micrograph of the negative structure corresponding to the biological surface nanostructure on the metal film.

Fig. 4 is an electron micrograph of the nanostructure of the organic polymer film prepared by the present invention.

In the picture:

1——Biological nanostructure 2——Organic glue

3——Silicon substrate 4——Metal film

5——Organic polymer film

Detailed ways

Example 1

(1) Adult cicada wings were ultrasonically cleaned in acetone for 5 minutes, then ultrasonically cleaned in ultrapure water for 2 minutes, and placed in air to dry naturally.

(2) Paste the cleaned and dried cicada wings on the surface of the silicon substrate with an organic adhesive, and place it in a vacuum coating machine, and vapor-deposit metal Au with a thickness of 300 nm under a vacuum condition of 10 ^-6 mbar.

(3) Take out the evaporated metal sample from the vacuum coating machine, use EPO-TEK 377 organic glue to bond the evaporated metal Au film to another silicon substrate under the condition of curing 1hr at 150°C, and remove the Au film from The surface of the cicada wing is peeled off, and a negative structure corresponding to the surface structure of the cicada wing is obtained on the surface of the Au film (the side closely attached to the cicada wing), as shown in FIG. 3 . This metal film is used as a template for secondary replication.

(4) the Au thin film that step (3) is obtained is placed in the container of a 2 * 2 * 2cm, to its surface casting 1ml is dissolved in the PMMA solution (15wt%) of anisole, under room temperature condition, leave standstill 10min, then Place in an oven and bake at 60°C for 30 minutes to evaporate the organic solvent anisole. Then the cured PMMA film is peeled off from the surface of the Au film to obtain a PMMA film with a flap surface nanostructure, as shown in Figure 4.

Example 2

(1) Adult cicada wings were ultrasonically cleaned in acetone for 5 minutes, then ultrasonically cleaned in ultrapure water for 2 minutes, and placed in air to dry naturally.

(2) The cleaned and dried cicada wings were pasted on the surface of the silicon substrate with an organic adhesive, placed in a vacuum coating machine, and 500 nm thick metal Au was vapor-deposited under a vacuum condition of 10 ⁻⁶ mbar.

(3) Take out the evaporated metal sample from the vacuum coating machine, use EPO-TEK 377 organic glue to bond the evaporated metal Au film to another silicon substrate under the condition of curing 1hr at 150°C, and remove the Au film from The surface of the cicada wing is peeled off, and a negative structure corresponding to the surface structure of the cicada wing is obtained on the surface of the Au film (the side closely attached to the cicada wing). This metal film is used as a template for secondary replication.

(4) the Au thin film that step (3) is obtained is placed in the container of a 2 * 2 * 2cm, to its surface casting 1ml is dissolved in the PMMA solution (15wt%) of anisole, under room temperature condition, leave standstill 10min, then Place in an oven and bake at 60°C for 60 minutes to evaporate the organic solvent anisole. Then the cured PMMA film is peeled off from the surface of the Au film to obtain a PMMA film with a flap surface nanostructure.

Example 3

(1) Adult cicada wings were ultrasonically cleaned in acetone for 5 minutes, then ultrasonically cleaned in ultrapure water for 2 minutes, and placed in air to dry naturally.

(2) The cleaned and dried cicada wings were pasted on the surface of the silicon substrate with an organic adhesive, placed in a vacuum coating machine, and 500 nm thick metal Au was vapor-deposited under a vacuum condition of 10 ⁻⁶ mbar.

(3) Take out the evaporated metal sample from the vacuum coating machine, use EPO-TEK 377 organic glue to bond the evaporated metal Au film to another silicon substrate under the condition of curing 1hr at 150°C, and remove the Au film from The surface of the cicada wing is peeled off, and a negative structure corresponding to the surface structure of the cicada wing is obtained on the surface of the Au film (the side closely attached to the cicada wing). This metal film is used as a template for secondary replication.

(4) the Au thin film that step (3) is obtained is placed in the container of a 2 * 2 * 2cm, to its surface casting 1ml is dissolved in the PMMA solution (15wt%) of anisole, under room temperature condition, leave standstill 10min, then Place in an oven and bake at 90°C for 30 minutes to evaporate the organic solvent anisole. Then the cured PMMA film is peeled off from the surface of the Au film to obtain a PMMA film with a flap surface nanostructure.

(5) with the metal Au thin film that step (3) obtains as the same template, repeat step (4) twice to obtain the PMMA thin film of the same structure.

Example 4

(1) Adult cicada wings were ultrasonically cleaned in acetone for 5 minutes, then ultrasonically cleaned in ultrapure water for 2 minutes, and placed in air to dry naturally.

(2) The cleaned and dried cicada wings were pasted on the surface of the silicon substrate with an organic adhesive, placed in a vacuum coating machine, and 500 nm thick metal Au was vapor-deposited under a vacuum condition of 10 ⁻⁶ mbar.

(3) Take out the evaporated metal sample from the vacuum coating machine, use EPO-TEK 377 organic glue to bond the evaporated metal Au film to another silicon substrate under the condition of curing 1hr at 150°C, and remove the Au film from The surface of the cicada wing is peeled off, and a negative structure corresponding to the surface structure of the cicada wing is obtained on the surface of the Au film (the side closely attached to the cicada wing). This metal film is used as a template for secondary replication.

(4) the Au thin film that step (3) is obtained is placed in the container of a 2 * 2 * 2cm, to its surface casting 1ml is dissolved in the PMMA solution (15wt%) of anisole, under room temperature condition, leave standstill 10min, then Place in an oven and bake at 170°C for 30 minutes to evaporate the organic solvent anisole. Then the cured PMMA film is peeled off from the surface of the Au film to obtain a PMMA film with a flap surface nanostructure.

Example 5

(1) Adult cicada wings were ultrasonically cleaned in acetone for 5 minutes, then ultrasonically cleaned in ultrapure water for 2 minutes, and placed in air to dry naturally.

(2) The cleaned and dried cicada wings were pasted on the surface of the silicon substrate with an organic adhesive, placed in a vacuum coating machine, and metal Cr with a thickness of 500 nm was evaporated under a vacuum condition of 10 ⁻⁶ mbar.

(3) Take out the vapor-deposited metal sample from the vacuum coating machine, and bond the vapor-deposited metal Cr film to another silicon substrate with EPO-TEK 377 organic glue at 150°C for 1 hr, and bond the metal Cr film Peel it off from the surface of the cicada wing, and obtain a negative structure corresponding to the surface structure of the cicada wing on the surface of the Cr film (the side that is close to the cicada wing), as shown in Figure 8. This metal film is used as a template for secondary replication.

(4) the Cr thin film that step (3) is obtained is placed in the container of a 2 * 2 * 2cm, toward its surface cast 1ml and be dissolved in the PMMA solution (15wt%) of anisole, leave standstill 10min under the room temperature condition, then Place in an oven and bake at 90°C for 30 minutes to evaporate the organic solvent anisole. Then the cured PMMA film is peeled off from the surface of the Cr film to obtain a PMMA film with a flap surface nanostructure.

Example 6

(1) Adult cicada wings were ultrasonically cleaned in acetone for 5 minutes, then ultrasonically cleaned in ultrapure water for 2 minutes, and placed in air to dry naturally.

(2) Paste the cleaned and dried cicada wings on the surface of the silicon substrate with an organic adhesive, and put them in a vacuum coating machine, and vapor-deposit metal Ti with a thickness of 500 nm under a vacuum condition of 10 ^-6 mbar.

(3) Take out the evaporated metal sample from the vacuum coating machine, use EPO-TEK 377 organic glue to bond the evaporated metal Ti film to another silicon substrate under the condition of curing at 150°C for 1 hr, and bond the metal Ti film Peel it off from the surface of the cicada wing, and obtain a negative structure corresponding to the surface structure of the cicada wing on the surface of the Ti film (the side that is close to the cicada wing), as shown in Figure 9. This metal film is used as a template for secondary replication.

(4) the Ti thin film that step (3) is obtained is placed in the container of a 2 * 2 * 2cm, toward its surface casting 1ml is dissolved in the PMMA solution (15wt%) of anisole, under room temperature condition, leave standstill 10min, then Place in an oven and bake at 90°C for 30 minutes to evaporate the organic solvent anisole. Then the cured PMMA film is peeled off from the surface of the Ti film to obtain a PMMA film with a flap surface nanostructure.

Example 7

(1) Adult cicada wings were ultrasonically cleaned in acetone for 5 minutes, then ultrasonically cleaned in ultrapure water for 2 minutes, and placed in air to dry naturally.

(2) The cleaned and dried cicada wings were pasted on the surface of the silicon substrate with an organic adhesive, placed in a vacuum coating machine, and 500 nm thick metal Ni was vapor-deposited under a vacuum condition of 10 ⁻⁶ mbar.

(3) Take out the vapor-deposited metal sample from the vacuum coating machine, use EPO-TEK 377 organic glue to bond the vapor-deposited metal Ni film to another silicon substrate under the condition of curing at 150°C for 1 hr, and bond the metal Ni film Peel it off from the surface of the cicada wing, and obtain a negative structure corresponding to the surface structure of the cicada wing on the surface of the Ni film (the side that is close to the cicada wing), as shown in Figure 10. This metal film is used as a template for secondary replication.

(4) the Au thin film that step (3) is obtained is placed in the container of a 2 * 2 * 2cm, to its surface casting 1ml is dissolved in the PMMA solution (15wt%) of anisole, under room temperature condition, leave standstill 10min, then Place in an oven and bake at 90°C for 30 minutes to evaporate the organic solvent anisole. Then the cured PMMA film is peeled off from the surface of the Ni film to obtain a PMMA film with a flap surface nanostructure.

Example 8

(1) Adult cicada wings were ultrasonically cleaned in acetone for 5 minutes, then ultrasonically cleaned in ultrapure water for 2 minutes, and placed in air to dry naturally.

(2) The cleaned and dried cicada wings were pasted on the surface of the silicon substrate with an organic adhesive, placed in a vacuum coating machine, and 500 nm thick metal Au was vapor-deposited under a vacuum condition of 10 ⁻⁶ mbar.

(3) Take out the evaporated metal sample from the vacuum coating machine, use EPO-TEK 377 organic glue to bond the evaporated metal Au film to another silicon substrate under the condition of curing 1hr at 150°C, and remove the Au film from The surface of the cicada wing is peeled off, and a negative structure corresponding to the surface structure of the cicada wing is obtained on the surface of the Au film (the side closely attached to the cicada wing). This metal film is used as a template for secondary replication.

(4) Place the Au film obtained in step (3) in a 2×2×2cm container, cast 0.5ml of polyurethane (PU) precursor on its surface, let it stand at room temperature for 5min, and then place it under 8w Irradiate under ultraviolet light for 30 minutes to cure, and finally peel off the cured polyurethane film from the surface of the Au film to obtain a polyurethane film with a nanostructure on the surface of cicada wings.

Example 9

The flap, the PMMA film obtained in Example 3 and the other unstructured PMMA film are optically characterized in the ultraviolet and visible light bands, and the optical instrument used is the Lambda 950 ultraviolet-visible-near-infrared spectrophotometer of PerkinEmler company. The characterization results show that in the ultraviolet and visible light bands, the reflectivity of the PMMA film obtained in Example 3 is 36% of that of the unstructured PMMA film, which shows that the PMMA film replicated by the technology of the present invention has stronger antireflection properties.

Claims (7)

1. the preparation method of an anti-reflection film, its step is as follows: be template vacuum evaporation layer of metal film with the biological nano structure at first, obtain on metallic film and the corresponding minus structure of biological nano structure; Be that template is cast with organic polymer with metal minus structure then, after solidifying, obtain the organic polymeric antireflective film that the surface has the nanostructured consistent with biological template, the compound eye that wherein said biological nano structure is a moth or the photonic crystal on cicada's wings surface.

2. preparation method as claimed in claim 1 is characterized in that: the material of described metallic film is selected from the alloy of gold, chromium, titanium, nickel, aluminium or above-mentioned metal.

3. preparation method as claimed in claim 1 is characterized in that: 10 ^-6Evaporation metal under the vacuum condition of mbar, evaporation speed are 0.15～0.50nm/s.

4. preparation method as claimed in claim 1 is characterized in that: described thickness of metal film is 300～500nm.

5. preparation method as claimed in claim 1 is characterized in that: described organic polymer is the organic polymer of elastic modulus greater than 1.2Gpa.

6. as the described preparation method of the arbitrary claim of claim 1～5, it is characterized in that: described organic polymer is a polymethylmethacrylate, and its condition of cure is 90～170 ℃ of baking 30～60min.

7. as the described preparation method of the arbitrary claim of claim 1～5, it is characterized in that: described organic polymer is a polyamine fat, and its condition of cure is 8w ultra violet lamp 15min～30min.

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