WO2012144954A1

WO2012144954A1 - Anti-reflective nanostructures

Info

Publication number: WO2012144954A1
Application number: PCT/SG2012/000132
Authority: WO
Inventors: Zsolt Szabo; Eng Huat KHOO; Tze Wei Martin ANG
Original assignee: Agency For Science, Technology And Research
Priority date: 2011-04-19
Filing date: 2012-04-16
Publication date: 2012-10-26

Abstract

An antireflective surface is provided. The antireflective surface includes a plurality of composite antireflective structures. Each of the plurality of composite antireflective structures includes a primary structure and a plurality of secondary structures formed on the primary structure. The primary structure has dimensions in the nanometer range and each of the plurality of secondary structures has dimensions in the nanometer range with the dimensions of each of the secondary structures being in a range that is approximately ten to fifteen per cent of the dimensions of the primary structure. For example, the primary structure has dimensions less than 500nm and the secondary structures have dimensions less than 50nm.

Description

ANTI-REFLECTIVE NANOSTRUCTURES

FIELD OF THE INVENTION

[0001] The present invention generally relates to antireflective nanostructures, and more particularly relates to two-part composite antireflective nanostructures.

BACKGROUND OF THE DISCLOSURE

[0002] Anti-reflection surfaces can be used with photovoltaic to improve solar cell light collection efficiency, with light sensors and optical devices to improve performance and with displays to improve contrast, reduce glare and prevent "ghost images". Conventional approaches to create antireflection surfaces by ordered surface structuring have used a "motheye" structure. The "motheye" structure imitates the eye structures of nocturnal insects, such as moths, which have unique antireflection property due to regular arrays of protrusions on the eye surface. "Motheye" structures have been artificially created using fabrication techniques such as interference lithography, photolithography and etching, and molding. Some companies have manufactured these structures on plastic films to create antireflection films. However, utilization of the "motheye" structures typically results in a lowest reflectivity of one per cent in the visible wavelength range (400-800nm). In addition, the films and the structures thereon typically lack robustness and scalability; in fact, many such structures require complex fabrication techniques to manufacture.

[0003] Thus, what is needed is an antireflective surface that achieves reflectivity less than one per cent and is scalable without complex fabrication. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims. taken_m_conjunctign_with_the- accompanying drawings and this background of the disclosure. SUMMARY

[0004] According to the Detailed Description, an antireflective surface is provided. The antireflective surface includes a plurality of composite antireflective structures. Each of the plurality of composite antireflective structures includes a first nanostructure and a plurality of second nanostructures formed on the first nanostructure. The first nanostructure has a diameter in a plane of the antireflective surface of less than 600nm, while each of the plurality of second nanostructures has a diameter in a plane tangent to a surface of the first nanostructure of less than 1 OOnm.

[0005] In accordance with another aspect, a composite antireflective structure is provided. The composite antireflective structure includes a primary structure and a plurality of secondary structures formed on the primary structure. The primary structure has dimensions in the nanometer range. And each of the plurality of secondary structures also has dimensions in the nanometer range, wherein the dimensions of each of the plurality of secondary structures are in a range that is approximately ten to fifteen percent of the dimensions of the primary structure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to illustrate various embodiments and to explain various principles and advantages in accordance with the present invention.

[0007] FIG. 1 illustrates a cross-sectional view of a composite antireflective structure of an antireflective surface in accordance with the present embodiment. [0008] FIG. 2 illustrates a graph of the reflectivity across the visible light spectrum of the primary structures and the secondary structures of the composite antireflective structure at various angles of reflection in accordance with the present embodiment.

[0009] FIG. 3, including FIGs. 3 A and 3B, illustrates graphs of reflectivity of the present embodiment in accordance with the present embodiment, wherein FIG. 3A illustrates a graph of the reflectivity of the secondary structures of the composite antireflective structure across various wavelengths and FIG. 3B illustrates a graph of the reflectivity of various structures of the composite antireflective structure.

[0010] FIG. 4, including FIGs. 4A and 4B, illustrates graphs of reflectivity across the visible light spectrum in relation to various angles of incidence of the light, wherein FIG. 4A illustrates a graph of the reflectivity across the visible light spectrum of a conventional pyramidal shaped structure at a thirty degree angle of incidence and FIG. 4B illustrates a graph of the reflectivity across the visible light spectrum at different angles of incidence projected on the composite antireflective structure in accordance with the present embodiment.

[0011] FIG. 5 is a top, front, right perspective of a portion of the antireflective surface depicting an arrangement of seven composite antireflective structures in accordance with the present embodiment.

[0012] FIG. 6 is a cross-sectional view of composite antireflective structures in accordance with the present embodiment.

[0013] FIG. 7 is a top, front, right perspective of a portion of an antireflective surface depicting an arrangement of seven composite antireflective structures including irregular spaced secondary structures in accordance with an alternate embodiment. [0014] And FIG. 8, including FIGs. 8A and 8B, depicts composite antireflective structures in accordance with yet another embodiment wherein the secondary structures are formed using a mold developed with carbon nanotubes, wherein FIG. 8A is a top planar view of a grouping of seven composite antireflective structures, and wherein FIG. 8B is a cross-sectional view of one of the composite antireflective structures.

[0015] Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures illustrating integrated circuit architecture may be exaggerated relative to other elements to help to improve understanding of the present and alternate embodiments.

DETAILED DESCRIPTION

[0016] The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description. It is the intent of this invention to manage and control the lubricant accumulation on a slider body by eliminating the impact of transferred lubricants to the slider body by channeling the lubricant to non-critical areas of the slider and containing it within lubricant reservoirs at those non-critical areas.

[0017] Referring to FIG. 1, a cross-sectional view 100 of a composite antireflective structure in accordance with the present embodiment is depicted. The view 100 illustrates the two-part antireflective composite structure including-a-primary_.structure- 102 and a plurality of secondary structures 104 formed on the primary structure. The nanostmcture 102 of the primary layer (i.e., the first nanostructure or the primary structure) is semi-spherical or parabolic shaped and the diameter of the primary structure is approximately 300nm. Each of the plurality of nanostructures 104 of the secondary layer (i.e., the second nanostructures or the secondary structures) has a pitch of 40 nm and a height of 20nm.

[0018] While the dimensions of the primary structure 102 are in the nanometer range (typically 600nm or less), the preferable dimensions of the primary nanostructure 102 include a diameter of 300nm or less, and a height in the range of lOOnm to 300nm. The dimensions of the secondary structures 104 are also in the nanometer range. Preferably, the dimensions of each of the plurality of secondary structures 104 include a diameter (as measured on a plane tangential to a surface of the primary structure 102) ranging between lOnm to 100 nm. Further, each of the plurality of secondary structures has a pitch of 40 nm or less.

[0019} The primary structure 102 can be semispherical, parabolic, or conical in shape, wherein the shape is selected to increase an incident light contact angle to the surface of the substrate of the primary structure 102 from a typical thirty degrees to sixty degrees. This advantageously increases light transmission due to higher angular acceptance angles. Reflectivity of 0.35% has been achieved at a minimum incident light angle of zero degrees (see FIG. 4B).

[0020] Each of the plurality of secondary structures 104 can also have a cross- section which is semi-spherical, parabolic, or conical in shape. The secondary structures 104 are nanostructures that are also shaped to further increase incident light contact angle to the surface of the substrate of the nanostructures from 30 degrees to 60 degrees.. In a further embodiment, the primary structure. 1.02 and the secondary structure 104 are made of a substrate of organic polymer-based materials such as polycarbonate, PMMA, acrylic or plastic.

[0021] Table 1 illustrates the optimal critical dimensions of the nanostructure of the primary structure 102 and each of the sub-nanostructures of the secondary structures 104. Experiments have shown that reflectivity is optimal at these dimensions.

Table 1

[0022] Referring to FIG. 2, graph 200depicts reflectivity (on y-axis 204) across the visible light spectrum (plotted on x-axis 202) of the primary structures and the secondary structures of the composite antireflective structure in accordance with the present embodiment. The various traces 206, 208, 210, 212, 214, 216, 218 show the reflectivity across the visible light spectrum at various angles of incidence of the light projected on the composite antireflective structure. At an angle of zero degrees (i.e., light perpendicular to the composite antireflective structure), the reflectivity across the visible light spectrum is shown by trace 206 in the graph 200. Similarly, traces 208, 210, 212, 214, 216, 218 show the reflectivity across the visible light spectrum at angles of incidence of, respectively, ten degrees, twenty degrees, thirty degrees, forty degrees, fifty degrees and sixty degrees. In the prior art, the lowest reflectivity achieved by the existing "motheyes" and hemisphere structures is 1% to 1.3%. The technical merits can be supported by the simulation results of our invention which produces the lowest reflectivity of 0.35% (at a wavelength of approximately 550nm and a zero degree angle of incidence as depicted on trace 206).

[0023] While typical "motheye" solutions achieve reflectivity in the one per cent range, some prior art approaches have attempted to achieve reflectivity below one per cent. For example, high aspect ratio "motheye" structures have been used to create a more gradual refractive index profile. However, the problem with such high aspect ratio structures is their robustness. An additional approach uses shape variations to the protrusions by using "S" shaped protrusions to reduce the reflectivity beyond one per cent. The disadvantage with this approach is the more complex fabrication necessary to achieve the "S" shape through a combination of widening and etching of the protrusion. Also, direct replication from the biotemplate of a compound "fly" eye structure has been attempted. However, this approach is only in a proof-of-concept stage of development and it is limited for practical applications as replication from the biotemplate of the fly-eye is not scalable. None of these prior art approaches has reported reflectivity of 0.15% (as seen towards the left end of the traces 206, 216) and these approaches have drawbacks of non-scalability, complex fabrication and lack of robustness. The present embodiment, as will be discussed in more detail, provides a robust, highly scalable solution with very low reflectivity.

[0024] Referring next to FIG. 3, including FIGs. 3A and 3B, graphs 300, 310 of reflectivity of the present embodiment in accordance with the present embodiment are depicted. FIG. 3A illustrates a graph 300 of the reflectivity (on y-axis 304) of the secondary structures 104 of the composite antireflective structure across various wavelengths (on x-axis 302) and FIG. 3B illustrates a graph 310 of the reflectivity (on y-axis 314) of various structures (plotted and depicted along x-axis 312) of the composite antireflective structure. Graphs 300, 310 illustrate the variation in reflectivity of the primary structure and the secondary structures over a range of dimensions and shapes. Referring to FIG. 3B, a trace 316 shows the change of shapes when the edges of the primary structures 102 have merged and the trace 318 shows the change in reflectivity due to the change of shapes when the edges of the primary structures 102 have not merged. In arrangement 320, the adjoining primary structures 102 overlap and the secondary structures 104 touch. The leftmost portion of trace 318 depicts the reflectivity of the arrangement 320. An arrangement 322 depicts adjoining primary structures 102 overlapping without the secondary structures. The leftmost portion of trace 316 depicts the reflectivity of the arrangement 322.

[0025] Arrangement 324 depicts the adjoining primary structures 102 touching. The center portions of traces 316, 318 depict the reflectivity of the arrangement 324. And arrangement 326 depicts the adjoining primary structures 102 not touching. The rightmost portions of traces 316, 318 depict the reflectivity of the arrangement 326.

[0026] Referring next to FIG. 4, including FIGs. 4A and 4B, graphs 400, 420 depict reflectivity across the visible light spectrum in relation to various angles of incidence of the light. FIG. 4A illustrates a graph 400 of the reflectivity (plotted along y-axis 410) across the visible light spectrum (plotted along x-axis 408) of a conventional pyramidal shaped structure 402 at a thirty degree angle of incidence 404. FIG. 4B illustrates a graph 420 of the reflectivity (plotted along y-axis 428) across the visible light spectrum (plotted along x-axis 426) of light at different angles of incidence 424 projected on the composite antireflective structure 422 in accordance with the present embodiment.

[0027] As the angle varies from zero degrees to sixty degrees in ten degree steps, the various traces 430, 432, 434, 436, 438, 440, 442 depict the reflectivity_of the composite antireflective structure 422. At zero degrees, the trace 430 shows that reflectivity is between 0.1% and 0.2%. In fact, reflectivity does not go over 0.3% until around forty degrees (see trace 438). Thus it can be seen that varying the angle of incidence can improve antireflectivity (i.e., decrease reflectivity). When light comes in at various angles of incidence, the effect of the composite antireflective structure 422 on the combined light still provides improved antireflectivity properties.

[0028] Referring to FIG. 5, a top, front, right perspective 500 of a portion of the antireflective surface 502 includes a cluster of composite antireflective structures 504 in accordance with the present embodiment. The arrangement of the composite antireflective structures 504 is illustrative of the preferred arrangement of the antireflective nanostructures arranged in a cluster.

[0029] The innovative shape and unique dimensions of the composite antireflective structure 504 on the surface 502 provides a low reflectivity of 0.5% and transmission of light at 99.5%, thereby improving the performance of visual displays and solar cells. As discussed hereinabove, the composite nanostructures are comprised of two layers of structures. The primary structures 102 (FIG. 1) are made up of semi- spherical shaped structures which have a diameter in the range of 200 to 400 nm. The layer of secondary structures 104 includes nanostructures of semi-spheres which have a diameter of 10 to 100 nm. The primary structures provide an anti-reflection property which has a reflectivity of 0.3% and the secondary structures further reduce the reflectivity to as low as 0.15%. The shape of the semi-spheres allows the incident contact angles of the light to increase from 30 degrees to 60 degrees. These technical merits result from the nanostructure 102, 104 being designed to constructively interface (in phase) a large percentage (99.85%) of the incident light, thereby allowing it to be transmitted through the surface of the substrate. [0030] The composite nanostructures achieve 0.5% reflectivity and 99.5% transmission of light. Currently, the state of art for anti-reflection coating has been able to achieve a reflectivity of 1% and transmission of light at 99%. The additional layer of sub-nanostructures designed and formed onto the low reflectivity primary anti-reflection structures advantageously achieves less than 0.5% reflectivity. Without an antireflection surface in accordance with the present embodiment (such as on a transparent plastic film or substrate), 6% to 10% of light is easily lost through reflection for displays and photovoltaic applications.

[0031] The present embodiment achieves the reduced reflectivity through certain key technical features. These key technical features are summarised in Table 2:

Table 2 [0032] Referring next to FIG. 6, a cross-sectional view 600 of composite antireflective structures 602, 604 in accordance with the present embodiment are illustrated. As seen in FIG. 6, the key feature in the robust antireflective design in accordance with the present embodiment lies in the second layer of smaller nanometer structures 608 having cross-sectional shapes of a pre-determinant shape arranged on top of the primary nanometer antireflection structures 606 to achieve the low reflectivity of less than 0.5%. However, it is difficult to produce the structures 608 in the nanometer range of 40 nm to 1 OOnm on the primary nanometer structures 606 which have the range of 200 nm to 600 nm. A scalable system of manufacturing the composite antireflective structures 602, 604 in accordance with the present embodiment can be achieved by double embossing using nanoimprinting technology. In this manner, an antireflection composite two-layer structure including unique dimensions of anti-reflection nanostructures providing a reflectivity of less than 0.5% and consequent transmission of light at 99.5% or above can be scalably provided, advantageously improving the performance of visual displays and solar cells.

[0033] Referring next to FIG. 7, a top, front, right perspective 700 of a portion of an antireflective surface 705 depicts an arrangement of seven composite antireflective structures including primary structures 710 and a plurality of secondary structures 720 in accordance with an alternate embodiment. The secondary structures 720 are irregularly spaced across a surface of the primary structure 710. As discussed in regards to FIG. 3B and FIG. 4 hereinabove, the spacing and shaping of the structures affect the incidence of light, thereby affecting the antireflective properties of the surface 705. The spacing and regularity/irregularity of the structures, both the primary structures 710 and the secondary structures 720, can be patterned_in_a manner to achieve the greatest reflectivity and such pattern can include secondary structures 720 regularly spaced across the surface of the primary structure 710 or such pattern can include secondary structures 720 irregularly spaced across the surface of the primary structure 710.

[0034] One such example of irregularly spaced secondary structures is depicted in FIG 8, including FIGs. 8A and 8B. A top planar view 800 of a cluster of composite antireflective structures shows spherical primary structures 810 and irregular secondary structures 820. The composite antireflective structures are formed by double embossed nanoimprinting and the mold used for nanoimprinting the secondary structures 820 is formed using carbon nanotubes. Using the secondary structure mold as described provides irregularity in spacing of the secondary structures 820 across a primary structure 810, as well as irregularity of the secondary structures 820 on various primary structures 810, as shown. Referring to FIG. 8B, a cross-sectional view 840 taken across line 830 (FIG. 8A) will perceive the cross-section of one or more secondary structures 820 as irregular shapes of non-uniform height, in part owing to the shape of the secondary structures 820, which in the top planar view 800 appear snake-like. Irregularity of the secondary structures 802 may also be appreciated in the different spacing between adjacent cross-sections of the secondary structures 820. Using carbon nanotubes to make nanoimprinting molds as described hereinabove allows a simple, scalable method for designing and forming antireflective surfaces having shape-determinant composite antireflective structures for optimizing the antireflective properties thereof.

[0035] Alternatively described, a composite antireflective structure is provided which comprises a primary structure having dimensions in the nanometer range and a plurality of secondary structures formed on a surface of the primary structure, each of the plurality secondary structures also having dimensions in the nanometer range, wherein the dimensions of each of the plurality of secondary structures is in a range of approximately ten per cent of the dimensions of the primary structure.

[0036] The composite antireflective structure may also have dimensions of the primary structure including a diameter less than 600nm.

[0037] Or the composite antireflective structure may have the diameter of the primary structure less than 300nm.

[0038] The composite antireflective structure may also have dimensions of the primary structure which include a height between lOOnm to 300nm.

[0039] Or the composite antireflective structure may have the dimensions of the plurality of secondary structures which include a diameter less than 1 OOnm.

[0040] Further, the composite antireflective structure may have the dimensions of the plurality of secondary structures which include a pitch of less than 40nm.

[0041] The composite antireflective structure may also have the pitch of each of the plurality of secondary structures is between 1 Onm to 40nm.

[0042] And the composite antireflective structure may include a shape of the primary structure that is selected from the group of shapes comprising a semispherical shape, a symmetrical cone shape and a parabolic shape.

[0043] Or the composite antireflective structure may include a shape of each of the plurality of secondary structures that is selected from the group of shapes comprising a semispherical shape, a symmetrical cone shape and a parabolic shape.

[0044] In addition, the composite antireflective structure may include the primary structure comprising a material selected from the group of organic polymer-based materials comprising polycarbonate, PMMA, acrylic, and plastic. [0045] Or the composite antireflective structure may have each of the plurality of secondary structures comprise a material selected from the group of organic polymer- based materials comprising polycarbonate, PMMA, acrylic, and plastic.

[0046] The composite antireflective structure may also have a shape of a cross- section of each of the plurality of secondary structures being selected from the group of shapes comprising a semispherical shape, a symmetrical cone shape and a parabolic shape.

[0047] Or the composite antireflective structure may have the plurality of secondary structures regularly spaced across the surface of the primary structure.

[0048] In addition, the composite antireflective structure may have the plurality of secondary structures that are irregularly spaced across the surface of the primary structure.

[0049] Further, the composite antireflective structure may have the primary structure and the plurality of secondary structures combine to provide a reflectivity of less than or equal to 0.5% and a transmittance equal to or greater than 99.5%.

[0050] An antireflective surface is also provided which comprises a plurality of composite antireflective structures, each of the plurality of composite antireflective structures comprising: a first nanostructure having a diameter in a plane of the antireflective surface of less than 600 nm, and a plurality of second nanostructures formed on the first nanostructure, each of the plurality second nanostructures having a diameter in a plane tangent to a surface of the first nanostructure of less than 100 nm.

[0051] This antireflective may have the diameter in the plane of the antireflective surface of the first nanostructure being less than 300nm and a pitch of the antireflective surface of the first nanostructure being between 100nm-_.and 30_.0nm. [0052] Or this antireflective surface may have the diameter of each of the plurality of second nanostructures in the plane tangent to the surface of the first nanostructure being less than 60nm and wherein a pitch of each of the plurality of second nanostructures being between lOnm and 40nm.

[0053] This antireflective surface may have a shape of the first nanostructure selected from the group of shapes comprising a semispherical shape, a symmetrical cone shape and a parabolic shape.

[0054] Or the antireflective surface may have a shape of a cross section of each of the plurality of second nanostructures selected from the group of shapes comprising a semispherical shape, a symmetrical cone shape and a parabolic shape. Finally, this antireflective surface may have the first nanostructure and each of the second nanostructures comprising a material selected from the group of organic polymer- based materials comprising polycarbonate, PMMA, acrylic, and plastic.

[0055] Thus it can be seen that an antireflective surface that achieves reflectivity less than one per cent and is scalable without complex fabrication has been provided. The antireflective surface includes a plurality of composite antireflective structures 602, 604. Each of the plurality of composite antireflective structures includes a first nanostructure 606 and a plurality of second nanostructures 608 formed on the first nanostructure. The first nanostructure has a diameter in a plane of the antireflective surface of less than 600nm, while each of the plurality of second nanostructures has a diameter in a plane tangent to a surface of the first nanostructure of less than lOOnm. While several exemplary embodiments have been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist, including variations as to the materials,_. shapes and dimensions used to form the various structures 102, 104, 606, 608. [0056] It should further be appreciated that the exemplary embodiments are only examples, and are not intended to limit the scope, applicability, dimensions, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements and method of fabrication described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.

Claims

CLAIMS What is claimed is:

1. A composite antireflective structure comprising:

a primary structure having dimensions in the nanometer range; and

a plurality of secondary structures formed on a surface of the primary structure, each of the plurality secondary structures also having dimensions in the nanometer range, wherein the dimensions of each of the plurality of secondary structures is in a range of approximately ten per cent of the dimensions of the primary structure.

2. The composite antireflective structure in accordance with Claim 1 wherein the dimensions of the primary structure include a diameter less than 600nm.

3. The composite antireflective structure in accordance with Claim 2 wherein the diameter of the primary structure is less than 3 OOnm.

4. The composite antireflective structure in accordance with Claim 3 wherein the dimensions of the primary structure include a height between 1 OOnm to 300nm.

5. The composite antireflective structure in accordance with Claim 1 wherein the dimensions of the plurality of secondary structures include a diameter less than lOOnm.

6. The composite antireflective structure in accordance with Claim 5 wherein the dimensions of the plurality of secondary structures include a pitch of less than 40nm.

7. The composite antireflective structure in accordance with Claim 6 wherein the pitch of each of the plurality of secondary structures is between 1 Onm to 40nm.

8. The composite antireflective structure in accordance with Claim 1 wherein a shape of the primary structure is selected from the group of shapes comprising a semispherical shape, a symmetrical cone shape and a parabolic shape.

9. The composite antireflective structure in accordance with Claim 1 wherein a shape of each of the plurality of secondary structures is selected from the group of shapes comprising a semispherical shape, a symmetrical cone shape and a parabolic shape.

10. The composite antireflective structure in accordance with Claim 1 wherein the primary structure comprises a material selected from the group of organic polymer-based materials comprising polycarbonate, PMMA, acrylic, and plastic.

1 1. The composite antireflective structure in accordance with Claim 1 wherein each of the plurality of secondary structures comprise a material selected from the group of organic polymer-based, materials comprising polycarbonate, PMMA, acrylic, and plastic.

12. The composite antireflective structure in accordance with Claim 1 wherein a shape of a cross-section of each of the plurality of secondary structures is selected from the group of shapes comprising a semispherical shape, a symmetrical cone shape and a parabolic shape.

13. The composite antireflective structure in accordance with Claim 1 wherein the plurality of secondary structures are regularly spaced across the surface of the primary structure.

14. The composite antireflective structure in accordance with Claim 1 wherein the plurality of secondary structures are irregularly spaced across the surface of the primary structure.

15. The composite antireflective structure in accordance with Claim 1 wherein the primary structure and the plurality of secondary structures combine to provide a reflectivity of less than or equal to 0.5% and a transmittance equal to or greater than 99.5%.

16. An antireflective surface comprising a plurality of composite antireflective structures, each of the plurality of composite antireflective structures comprising:

a first nanostructure having a diameter in a plane of the antireflective surface of less than 600 nm; and

a plurality of second nano structures formed on the first nanostructure, each of the plurality second nano structures having a diameter in a plane tangent to a surface of the first nanostructure of less than 100 nm.

17. The antireflective surface in accordance with Claim 16 wherein the diameter in the plane of the antireflective surface of the first nanostructure is less than 300nm and wherein a pitch of the antireflective surface of the first nanostructure is between lOOnm and 300nm.

18. The antireflective surface in accordance with Claim 16 wherein the diameter of each of the plurality of second nanostructures in the plane tangent to the surface of the first nanostructure is less than 60nm and wherein a pitch of each of the plurality of second nanostructures is between lOnm and 40nm.

19. The antireflective surface in accordance with Claim 16 wherein a shape of the first nanostructure is selected from the group of shapes comprising a semispherical shape, a symmetrical cone shape and a parabolic shape.

20. The antireflective surface in accordance with Claim 16 wherein a shape of a cross section of each of the plurality of second nanostructures is selected from the group of shapes comprising a semispherical shape, a symmetrical cone shape and a parabolic shape.

21. The antireflective surface in accordance with Claim 16 wherein the first nanostructure and each of the second nanostructures comprise a material selected from the group of organic polymer-based materials comprising polycarbonate, PMMA, acrylic, and plastic.