JP6549525B2 - Omnidirectional high chroma red structural color with combination of semiconductor absorber layer and dielectric absorber layer - Google Patents

Description

This application is a continuation-in-part of US patent application Ser. No. 14 / 607,933 filed on Jan. 28, 2015 (CIP), which is further filed on Aug. 28, 2014. No. 14 / 471,834 CIP, which is further a U.S. patent application no. 14 / 460,511 filed Aug. 15, 2014, CIP, which is also known as April 2014 A CIP of US Patent Application No. 14/242 429 filed on a one-day basis, which is further a CIP of US Patent Application No. 14/138 499 filed on Dec. 23, 2013, which is further No. 13 / 913,402, filed on Jun. 8, 2013, which is also CIP, which is further incorporated by reference into US patent application Ser. No. 13/7606, filed Feb. 6, 2013. 99 CIP, which is further the CIP of US patent application Ser. No. 13 / 57,2071, filed Aug. 10, 2012, all of which are incorporated by reference in their entirety.

  The present invention relates to multilayer laminate structures that exhibit high saturation red with minimal or unperceivable color shift when exposed to broadband electromagnetic radiation and observed from various angles.

  Pigments made from multilayer structures are known. In addition, pigments which exhibit or provide high chroma omnidirectional structural colors are also known. However, such prior art pigments required as many as 39 thin film layers to obtain the desired color characteristics.

  It is understood that the cost associated with the production of thin film multilayer pigments is proportional to the number of layers required. Thus, the cost associated with the production of high chroma omnidirectional structural colors using multilayer stacks of dielectric materials can be very high. Thus, a high saturation omnidirectional structural color is desirable which minimizes the number of thin film layers required.

  In addition to the above, it is also understood that red pigment designs face additional difficulties in addition to the case of pigments of other colors such as blue, green and the like. In particular, control of angular independence in the case of red requires thicker dielectric layers and results in higher harmonic designs, ie second and possibly third order It is difficult because the presence of harmonics is inevitable. Also, the dark red hue space is very narrow. Thus, the red multilayer laminate has higher angular variance.

  In view of the above, highly saturated red omnidirectional structural color pigments with a minimal number of layers are desirable.

An omnidirectional high chroma red structural color pigment is provided. The omnidirectional structural color pigment comprises a reflective core layer, a semiconductor absorber layer extending across the reflective core layer, a dielectric absorber layer extending across the semiconductor absorber layer, and a dielectric absorber layer. In the form of a multilayer stack having a high refractive index dielectric layer extending thereacross. The multilayer stack reflects a single band of visible light having a hue between 0-40 °, preferably 10-30 ° on the a ^* b ^* Lab color map. In addition, this single band of visible light is less than 30 ° on the a ^* b ^* Lab color map when viewed from all angles between 0 and 45 ° perpendicular to the outer surface of the multilayer stack And the resulting color shift is not perceived by the human eye.

  The reflective core layer has a thickness between 50 and 200 nanometers (nm), including the lower limit upper limit, and reflective metals such as aluminum (Al), silver (Ag), platinum (Pt), tin (Sn), combinations thereof, and the like. The reflective core layer may also be made of a colorful metal such as gold (Au), copper (Cu), brass, bronze and the like.

The semiconductor absorber layer may have a thickness of between 5 and 500 nm, including the lower limit, and may be made of materials such as amorphous silicon (Si), germanium (Ge), and combinations thereof. The dielectric absorber layer may have a thickness of 5 to 500 nm, including upper limits, and may be made of materials such as, but not limited to, iron oxide (Fe ₂ O ₃ ).

The thickness of the high refractive index dielectric layer is greater than and less than 4 QW from the quarter wave thickness (QW) for the target wavelength, and the target wavelength is a ^* b ^* have a defined hue in the range between 0-40 °, preferably 10-30 °, on the Lab color map. The high refractive index dielectric layer is a dielectric material such as zinc sulfide (ZnS), titanium dioxide (TiO ₂ ), hafnium oxide (HfO ₂ ), niobium oxide (Nb ₂ O ₅ ), tantalum oxide (Ta ₂ O ₅ ) , And combinations of these.

  The reflective core layer, the semiconductor absorber layer, and / or the dielectric absorber layer may be a dry deposit layer, while the high refractive index dielectric layer may be a wet deposit layer. In addition, the reflective core layer may be a central reflective core layer, and the semiconductor absorber layer may be a pair of semiconductor absorber layers extending across the central reflective core layer, ie The central reflective core layer is sandwiched between a pair of semiconductor absorber layers. Furthermore, the dielectric absorber layer may be a pair of dielectric absorber layers, whereby the central reflective core layer and the pair of semiconductor absorber layers are sandwiched between the pair of dielectric absorber layers . Finally, the high refractive index dielectric layer may be a pair of high refractive index layers, whereby the central reflective core layer, the pair of semiconductor absorber layers, and the pair of dielectric absorber layers are: It is sandwiched between a pair of high refractive index dielectric layers.

  A process for producing such an omnidirectional high chroma red structural color comprises dry depositing a reflective core layer, dry depositing a semiconductor absorber layer extending over the reflective core layer, and over the semiconductor absorber layer. Manufacturing the multilayer stack by dry depositing an extending dielectric absorber layer. Next, a high refractive index dielectric layer extending across the semiconductor absorber layer is wet deposited thereon. By this method, a hybrid manufacturing process is used to create an omnidirectional high chroma red structural color that can be used for pigments, coatings, and the like.

FIG. 1 is a schematic view of an omnidirectional structural color multilayer laminate made from a dielectric layer, a selective absorption layer (SAL), and a reflector layer. FIG. 2A is a schematic view of a zero or near zero field point in a ZnS dielectric layer exposed to electromagnetic radiation (EMR) having a wavelength of 500 nm. FIG. 2B shows the square of the absolute value of the electric field with respect to the thickness of the ZnS dielectric layer shown in FIG. 2A (| E | ² ) when exposed to EMR having a wavelength of 300, 400, 500, 600 and 700 nm. ) Is shown graphically. FIG. 3 is a schematic view of a dielectric layer spread over a substrate or reflector layer and exposed to electromagnetic radiation at an angle θ relative to the perpendicular to the outer surface of the dielectric layer. FIG. 4 is a schematic of a ZnS dielectric layer having a Cr absorber layer located at a zero or near zero field point in the ZnS dielectric layer for an incident EMR having a wavelength of 434 nm. FIG. 5 shows the reflectance to the reflective EMR wavelength in a multilayer laminate without a Cr absorber layer exposed to white light (eg: FIG. 2A) and in a multilayer laminate with a Cr absorber layer (eg: FIG. 4) The percentages are shown graphically. FIG. 6A is a graph showing the first and second harmonics exhibited by a ZnS dielectric layer (eg, FIG. 2A) extending over an Al reflector layer. FIG. 6B shows, in addition to the ZnS dielectric layer extending over the Al reflector layer, a Cr absorber layer disposed in the ZnS dielectric layer such that the second harmonic shown in FIG. 6A is absorbed. FIG. 5 graphically illustrates the percent reflectance versus the reflective EMR wavelength in a multilayer stack having: FIG. FIG. 6C has a Cr absorber layer disposed in the ZnS dielectric layer such that the first harmonic shown in FIG. 6A is absorbed, in addition to the ZnS dielectric layer extending across the Al reflector layer FIG. 6 graphically illustrates the percent reflectance versus the reflective EMR wavelength in a multilayer stack. FIG. 7A is a graphical representation of the square of the electric field versus the dielectric layer thickness showing the angular dependence of the electric field of the Cr absorber layer upon exposure to 0 and 45 degrees incident light. FIG. 7B shows the percent absorptivity by the Cr absorber layer to the reflected EMR wavelength when exposed to white light at angles of 0 and 45 ° with respect to the vertical direction of the outer surface (0 ° perpendicular to the surface) Is shown graphically. FIG. 8A is a schematic view of a red omnidirectional structural color multilayer laminate in the aspect disclosed herein. FIG. 8B graphically illustrates the percent absorptivity of the Cu absorber layer shown in FIG. 8A against the reflected EMR wavelength when the multilayer stack shown in FIG. 8A is exposed to white light at incident angles of 0 and 45 °. It is FIG. 9 is a graph showing a comparison of calculated / simulated data with experimental data for percent reflectance versus reflected EMR wavelength in a proof-of-concept red omnidirectional color multilayer stack exposed to white light at an incidence angle of 0 °. It is. FIG. 10 is a graphical representation of the percent reflectance versus wavelength for the omnidirectional structural color multilayer stack in the embodiments disclosed herein. FIG. 11 is a graphical representation of the percent reflectance versus wavelength for the omnidirectional structural color multilayer laminate in the aspect disclosed herein. FIG. 12 graphically depicts a portion of the a ^* b ^* color map using the CIELAB (Lab) color space, a paint made from a conventional paint and a pigment in the embodiments disclosed herein. The chroma and hue shifts of (sample (b)) are compared. FIG. 13 is a schematic view of a red omnidirectional structural color multilayer laminate in accordance with another aspect disclosed herein. FIG. 14 is a graphical representation of the percent reflectance versus wavelength for the embodiment shown in FIG. FIG. 15 is a graphical representation of the percent absorptivity versus wavelength for the embodiment shown in FIG. FIG. 16 is a graphical representation of percent reflectance versus wavelength versus viewing angle for the embodiment shown in FIG. FIG. 17 is a graph showing the saturation and the hue with respect to the observation angle in the embodiment shown in FIG. FIG. 18 is a graphical representation of the color reflected by the multilayer stack shown in FIG. 13 for the a ^* b ^* Lab color map. FIG. 19 is a schematic view of a process for manufacturing an omnidirectional red structural color multilayer laminate in the embodiments disclosed herein.

  An omnidirectional high chroma red structural color pigment is provided. The omnidirectional high chroma red structured color pigment is in the form of a multilayer stack having a reflective core layer, a semiconductor absorber layer, a dielectric absorber layer, and a high refractive index dielectric layer. The semiconductor absorber layer extends across the reflective core layer, and in some instances, is in direct contact with or on the reflective core layer. The dielectric absorber layer extends across the semiconductor absorber layer, and in some instances is in direct contact with or on the semiconductor absorber layer. The high refractive index dielectric layer extends across the semiconductor absorber layer, and in some instances is in direct contact with or on the semiconductor absorber layer. The multilayer stack may be a symmetrical stack, ie, the reflective core layer is a central reflective core layer adjacent to a pair of semiconductor absorber layers, the pair of semiconductor absorber layers is a pair of dielectrics. Adjacent to the body absorber layer, and a pair of dielectric semiconductor layers, the pair of semiconductor absorber layers is adjacent to a pair of high refractive index dielectric layers.

The multilayer stack reflects a single band of visible light having a red color of hue between 0-40 °, preferably between 10-30 ° on the a ^* b ^* Lab color map. In addition, this single-band hue shift of visible light is a ^* b ^* Lab color when looking at the multilayer stack from all angles between 0 and 45 degrees normal to the outer surface of the multilayer stack. Less than 30 °, preferably less than 20 °, more preferably less than 10 ° on the map. Thus, the single-band hue shift of the reflected visible light may be in the region of 0-45 °, preferably between 10-30 °, on the a ^* b ^* Lab color map.

  The reflective core layer may be a dry deposit layer having a thickness of between 50 and 200 nm, including the lower limit. The term "dry deposition" refers to dry deposition methods such as physical vapor deposition (PVD) methods including electron beam evaporation, sputtering, chemical vapor deposition (CVD), plasma CVD, and the like. In some instances, the reflective core layer is made of a reflective metal such as Al, Ag, Pt, Sn, combinations thereof, and the like. In another example, the reflective core layer is made of colored metals such as Au, Cu, brass, bronze, combinations thereof, and the like. The terms "brass" and "bronze" are understood to mean copper-zinc alloys and copper-tin alloys, respectively, which are known to the person skilled in the art.

  The semiconductor absorber layer may also be a dry deposit layer deposited on the reflective core layer. As another option, a reflective core layer may be deposited on the semiconductor absorber layer. The semiconductor absorber layer may have a thickness of between 5 and 500 nm, including the lower limit upper limit, and may be made of semiconductor materials such as amorphous silicon, germanium, combinations thereof, and the like. .

The dielectric absorber layer may also be a dry deposit layer deposited on the semiconductor absorber layer. As another option, a semiconductor absorber layer may be deposited on the dielectric absorber layer. The dielectric absorber layer may have a thickness of between 5 and 500 nm, including the lower limit and be made of a dielectric material such as iron oxide (Fe ₂ O ₃ ) and the like Good.

The high refractive index dielectric layer may be a wet deposited layer, where the term "high refractive index" means a refractive index greater than 1.6. Also, the term "wet deposition" refers to wet deposition methods such as sol-gel methods, spin coating methods, wet chemistry deposition techniques, and the like. The high refractive index dielectric layer has a thickness D according to 0.1QW <D ≦ 4QW, where QW is a quarter wave thickness for the wavelength of interest, ie, QW = λ _t / 4. Where λ _t is the target or desired reflection wavelength. The wavelength of interest has a predefined hue within the range of 0-40 °, preferably 10-30 °, on the a ^* b ^* Lab color map. In some examples, the wavelength of interest is between 600 to 700 nanometers, a dielectric layer, a dielectric material, for example _{ZnS, TiO 2, HfO 2,} Nb 2 O 5, Ta 2 O 5, of It is made from combinations and the like.

  The total thickness of the multilayer laminate may be less than 3 microns, preferably less than 2 microns, more preferably less than 1.5 microns, and even more preferably 1.0 microns or less. In addition, the multilayer laminate may have a total of 9 or less layers, preferably a total of 7 or less layers, more preferably a total of 5 or less layers.

Referring to FIG. 1, the design has a first dielectric material layer DL ₁ with an underlying reflector layer (RL) extending thereover, and a selective absorbing layer SAL extending over the DL ₁ layer. , Indicated. In addition, another DL ₁ layer may be provided, which may or may not extend across the selective absorption layer. The figure also shows that all incident electromagnetic radiation is either reflected or selectively absorbed by the multilayer structure.

  The design as shown in FIG. 1 corresponds to the different approaches used for the design and manufacture of the desired multilayer stack. In particular, zero or near-zero energy point thickness in the dielectric layer is used and is discussed below.

  For example, FIG. 2A is a schematic view of a ZnS dielectric layer extending across an Al reflector core layer. The ZnS dielectric layer has a total thickness of 143 nm, and for incident electromagnetic radiation at a wavelength of 500 nm, an energy point near or near zero exists at 77 nm. In other words, the ZnS dielectric layer exhibits an electric field near or near zero at a distance of 77 nm from the Al reflector layer for incident electromagnetic radiation (EMR) having a wavelength of 500 nm. In addition, FIG. 2B provides a graphical representation of the energy field across the ZnS dielectric layer at several different incident EMR wavelengths. As shown in the graph, the dielectric layer has a zero field at a thickness of 77 nm for a wavelength of 500 nm, but at an EMR wavelength of 77 nm for an EMR wavelength of 300, 400, 600, and 700 nm is zero. Absent.

Regarding the calculation of the electric field points at or near zero, FIG. 3 shows the total thickness "D", the incremental thickness "d", and the refractive index "n" on the substrate or core layer 2 having a refractive index n _s And a dielectric layer 4 having the Incident light strikes the outer surface 5 of the dielectric layer 4 at an angle θ relative to the line 6 which is perpendicular to the outer surface 5 and reflects from the outer surface 5 at the same angle θ. Incident light is transmitted through the outer surface 5 into the dielectric layer 4 at an angle θ _F relative to the line 6 and impinges on the surface 3 of the substrate layer 2 at an angle θ _s .

In a single dielectric layer, θ _s = θ _F and energy / electric field (E) can be expressed as E (z), where z = d. From Maxwell's equation, the electric field is for s-polarization:

  For p-polarization, which can be expressed as:

Where k = 2π / λ, where λ is the wavelength desired to be reflected. Also, an alpha = n _s sin [theta _s, where "s" corresponds to the substrate of FIG. 5,

  Is the dielectric constant of the layer as a function of z. Thus, for s-polarization

  And for p-polarization,

  It is.

  It is understood that the variation of the electric field along the Z direction of the dielectric layer 4 can be estimated by calculation of the unknown parameters u (z) and v (z), where it is indicated as follows You can:

  Of course, "i" is the square root of -1. boundary condition

And the following relationship:
For s-polarization, q _s = n _s cosθ _s (6)
For p-polarization, q _s = n _s / cos θ _s (7)
For s-polarization, q = n cos θ _F (8)
For p-polarization, q = n / cos θ _F (9)
φ = k · n · d cos (θ _F ) (10)
U (z) and v (z) are

  It can be expressed as Thus, for s-polarization:

Where, φ = k · n · d cos (θ _F ), for p-polarization:

And here:
α = n _s sin θ _s = n sin θ _F (15)
q _s = n _s / cos θ _s (16) and q _s = n / cos θ _F (17)
It is.

Thus, for a simple situation where θ _F = 0, or normal incident light, φ = k · n · d and α = 0:

  This makes it possible to solve the equation for thickness "d", i.e. for a position or location in the dielectric layer where the electric field is zero.

  Referring now to FIG. 4, Equation 19 was used to calculate zero or near zero field points in the ZnS dielectric layer shown in FIG. 2A when exposed to an EMR having a wavelength of 434 nm. The field point at or near zero was calculated to be 70 nm (as opposed to 77 nm for a wavelength of 500 nm). Furthermore, a 15 nm thick Cr absorber layer was inserted at a thickness or distance of 70 nm from the Al reflector core layer to obtain a ZnS-Cr interface with an electric field near or near zero. In such an inventive structure, light having a wavelength of 434 nm is transmitted through the Cr-ZnS interface but absorbs light having a wavelength of 434 nm. In other words, the Cr-ZnS interface has an electric field near or near zero for light having a wavelength of 434 nm, so light at 434 nm is transmitted through this interface. However, the Cr-ZnS interface does not have an electric field near or near zero for light which does not have a wavelength of 434 nm, and thus such light is a Cr absorber layer and / or a Cr-ZnS. It is absorbed by the interface and not reflected by the Al reflector layer.

  It is understood that the desired percentage of light within ± 10 nm of 434 nm is transmitted through the Cr—ZnS interface. However, it is also understood that such narrow band reflected light, for example 434 ± 10 nm, still provides a sharp structural color to the human eye.

  The results for the Cr absorber layer in the multilayer stack of FIG. 4 are shown in FIG. 5 where the percent reflectance for the reflected EMR wavelength is shown. A narrow reflection peak is present at about 400 nm, but a much broader peak is present at about 550+ nm, as shown by the dashed line corresponding to the ZnS dielectric layer shown in FIG. 4 without the Cr absorber layer. Do. In addition, significant amounts of reflected light are still present in the 500 nm wavelength range. Thus, there are double peaks that prevent the multilayer stack from having or exhibiting a structural color.

  In contrast, the solid line in FIG. 5 corresponds to the structure shown in FIG. 4 with a Cr absorber layer. As shown in the figure, there is a sharp peak at about 434 nm, and a sharp decrease in reflectance for wavelengths above 434 nm is obtained by the Cr absorber layer. It is understood that the sharp peaks represented by the solid lines appear visually as sharp / structural colors. Also shown in FIG. 5 is the position at which the width of the reflection peak or band is measured, ie the width of the band is specified at 50% reflectance of the maximum reflection wavelength, which is the full width at half maximum (FWHM) Also known as

  For the omnidirectional behavior of the multilayer stack shown in FIG. 4, the thickness of the ZnS dielectric layer can be designed or set so that only the first harmonic of the reflected light is obtained. While this is sufficient for the "blue" color, it is understood that the generation of the "red" color requires further consideration. For example, a thicker dielectric layer is required, and as a result, higher order harmonic designs, ie, the angular independence of the red, since the presence of second and possibly third order harmonics is inevitable Control is difficult. Also, the dark red hue space is very narrow. Thus, the red multilayer laminate has higher angular variation.

To overcome the high angular variation for red, the present application discloses a unique and novel design / structure that results in red that is angle independent. For example, FIG. 6A shows a dielectric layer that exhibits first and second harmonics to incident white light when the outer surface of the dielectric layer is observed from 0 and 45 degrees to the normal of the outer surface. Is shown. As shown by the graphical illustration, the thickness of the dielectric layer gives a low angular dependence (small Δλ _c ), but such multilayer stacks are blue (first harmonic) and red (second harmonic) Wave) and thus not suitable for the case of the desired "red only" color. Accordingly, concepts / structures have been developed that use an absorber layer to absorb unwanted harmonic sequences. FIG. 6A also shows the position of the central wavelength (λ _c ) of the reflection band with respect to a reflection peak and the dispersion or shift (Δλ _c ) of the central wavelength when the sample is observed from 0 and 45 °. An example is also shown.

Referring now to FIG. 6B, the second harmonic shown in FIG. 6A is absorbed by the Cr absorber layer at a suitable dielectric layer thickness (eg 72 nm) to obtain a sharp blue color. Also, FIG. 6C shows that a red color can be obtained by absorbing the first harmonics by Cr absorbers at different dielectric layer thicknesses (eg 125 nm). However, FIG. 6C also shows that the use of a Cr absorber layer can result in greater angular dependence than desired by the multilayer stack, ie, Δλ _c greater than desired.

That the shift of λ _c for red is relatively large compared to blue is that the dark red hue space is very narrow and that the Cr absorber layer absorbs the wavelength associated with the non-zero electric field, ie It is understood that it is due to not absorbing light when the electric field is at or near zero. Thus, FIG. 7A shows that at different angles of incidence, the zero or non-zero field points for the light wavelength are different. Such factors result in the angular dependent absorption shown in FIG. 7B, ie, differences in the 0 ° and 45 ° absorption curves. Thus, in order to further improve the design and the angle-independent performance of the multilayer stack, absorber layers are used which absorb, for example, blue light regardless of whether the electric field is zero or non-zero.

  In particular, FIG. 8A shows a multilayer stack in which a Cu absorber layer extends across the dielectric ZnS layer instead of the Cr absorber layer. The results using such “colored” or “selective” absorber layers are shown in FIG. 8B, which shows that the 0 ° and 45 ° absorption curves in the multilayer stack shown in FIG. 8A are very “more It shows that they are "tightly" organized. Therefore, comparison of FIG. 8B with FIG. 7B shows that the angular independence of absorption is greatly improved when the selective absorber layer is used instead of the nonselective absorber layer.

  Based on the above, a proof of concept multilayer laminate was designed and manufactured. In addition, calculation / simulation results and actual experimental data for proof-of-concept samples were compared. In particular, as shown by the plot of the graph in FIG. 9, a sharp red color is generated (wavelengths above 700 nm are usually not visible to the human eye), and experimental light obtained from calculations / simulations and actual samples The data matched very well. In other words, the calculations / simulation can simulate and / or simulate the results of the multilayer laminate design and / or the prior art multilayer laminate in one or more embodiments disclosed herein. Used for

  FIG. 10 is a plot of percent reflectance versus reflected EMR wavelength in another omnidirectional reflector design when exposed to white light from angles of 0 and 45 degrees with respect to the vertical direction of the outer surface of the reflector. Show. As shown by this plot, at wavelengths less than 550 nm, both the 0 ° and 45 ° curves provide very low reflectivity, eg less than 10%, by this omnidirectional reflector Is shown. However, as shown by these curves, the reflector shows a sharp increase in reflectance at wavelengths between 560 and 570 nm, reaching a maximum of approximately 90% at 700 nm. It is understood that the portion or area of the graph to the right (IR side) of the curve represents the IR portion of the reflection band provided by the reflector.

The sharp increase in reflectance provided by the omnidirectional reflector is the UV-sided edge of each curve, eg> 70, extending from the low reflectance portion at wavelengths less than 550 nm to the high reflectance portion. It is characterized by%. The linear portion 200 at the UV end has an inclination of length L and 1.4, which is inclined at an angle (β) of more than 60 ° to the x-axis and approximately 40 on the reflectivity axis. The straight portion may be inclined at an angle of more than 70 ° with respect to the x-axis, and β may be more than 75 °. Also, the reflection band has a visible FWHM of less than 200 nm, in some instances a visible FWHM of less than 150 nm, and in other instances a visible FWHM of less than 100 nm. In addition, the central wavelength λ _c of the visible reflection band shown in FIG. 10 is defined as the wavelength equidistant from the UV end of the reflection band in the visible FWHM and the IR end of the IR spectrum.

  The reflection band between the UV-side end of this curve and the end of the IR spectral range beyond which the reflection provided by the omnidirectional reflector is invisible to the human eye, as the term "visible FWHM" It is understood to mean the width of. By this method, the inventive design and multilayer laminates disclosed herein provide sharp or structural colors by using the invisible IR portion of the electromagnetic radiation spectrum. In other words, the omnidirectional reflector disclosed herein is capable of reflecting narrow bands of reflected light despite the fact that the reflector can reflect a much wider band of electromagnetic radiation extending into the IR region. The invisible IR portion of the electromagnetic radiation spectrum is utilized to provide light.

Referring now to FIG. 11, a plot of percent reflectance versus wavelength for another seven layer design omnidirectional reflector when exposed to white light from angles of 0 and 45 degrees with respect to the plane of the reflector. Is shown. In addition, a definition or characterization of the omnidirectional characteristics provided by the omnidirectional reflector disclosed herein is also shown. In particular, if the reflection band provided by the reflector of the invention has a maximum or peak, as shown in the figure, each curve is defined as the central wavelength defined as the wavelength exhibiting or causing the maximum reflectance ( It has λ _c ). The term of maximum reflection wavelength may be used for λ _c .

As shown in FIG. 11, if the outer surface of the omnidirectional reflector is viewed from an angle of 45 °, for example, if the outer surface is tilted 45 ° with respect to the human eye viewing the surface (λ _c (45 ^o )), shift or displacement of λ _c as compared to when the face is observed at an angle of 0 °, ie perpendicular to the face ((λ _c (0 ^o )) This shift in λ _c (Δλ _c ) provides a measure of the omnidirectional character of the omnidirectional reflector: Of course, zero shift, ie a completely omnidirectional reflector if no shift occurs at all. However, the omnidirectional reflector disclosed herein can provide a Δλ _c of less than 50 nm, which causes the face of the reflector to change color in the human eye. It looks as if there were no, so from a practical point of view this reflector is omnidirectional In some instances, the omnidirectional reflectors disclosed herein can provide Δλ _c of less than 40 nm, in other instances Δλ _c of less than 30 nm, and in yet other instances a [Delta] [lambda] _c of less than 20 nm, still yet another example, a [Delta] [lambda] _c of less than 15 nm. such a shift of [Delta] [lambda] _c is the plot of the actual reflectance versus wavelength of the reflector, and / or other As an option, if the materials and layer thicknesses are known, they can be identified by reflector modeling.

Another definition or characterization of the omnidirectional characteristics of the reflector can be specified by the shift of the side edge with respect to a set of angular reflection bands. For example, referring to FIG. 11, the UV side edge (S _UV (0 ^o )) for the reflection from the omnidirectional reflector observed from 0 °, the UV for the reflection by the same reflector observed from 45 ° The shift or displacement (ΔS _UV ) compared to the side edge (S _UV (45 ^o )) provides a measure of the omnidirectional character of the omnidirectional reflector. It is understood that the UV side end shift (ΔS _UV ) may be measured and / or be measured in the visible FWHM.

Of course, a zero shift, ie no shift at all (ΔS _UV = 0 nm), would be characterized as a completely omnidirectional reflector. However, the omnidirectional reflector disclosed herein can provide a ΔS _UV of less than 50 nm, as it appears to the human eye that the face of the reflector has not changed color. As such, from a practical point of view this reflector is omnidirectional. In some examples, the omnidirectional reflector disclosed herein can provide ΔS _UV of less than 40 nm, in other examples, ΔS _UV of less than 30 nm, and in yet other examples, It is a ΔS _UV of less than 20 nm, and in yet another example, a ΔS _UV of less than 15 nm. Such shifts in ΔS _UV may be identified by plotting the actual reflectance versus wavelength in the reflector and / or, alternatively, by modeling the reflector if the material and layer thicknesses are known. can do.

The shift in omnidirectional reflection can also be evaluated by a low hue shift. For example, the hue shift of the pigment produced from the multilayer laminate in the embodiments disclosed herein is 30 ° or less, as shown in FIG. 12 (see, eg, Δθ ₁ ), and in some instances, the hue. The shift is 25 ° or less, preferably less than 20 °, more preferably less than 15 °, and even more preferably less than 10 °. In contrast, conventional pigments exhibit hue shifts of 45 ° or more (see, eg, Δθ ₂ ). The hue shift associated with Δθ ₁ generally corresponds to red, but the low hue shift is appropriate for any color reflected by the hybrid omnidirectional structural color pigment disclosed herein It is understood.

  A schematic of an omnidirectional multilayer laminate in accordance with another aspect disclosed herein is shown at 10 in FIG. The multilayer stack 10 has a first layer 110, a second layer 120, and a third layer 130. A reflector layer 100 may be included, as desired. Examples of materials for the reflector layer 100, which may also be referred to as a reflector core layer, include, but are not limited to, Al, Ag, Pt, Cr, Cu, Zn, Au, Sn, and combinations thereof Or alloys may be mentioned. Thus, the reflector layer 100 may be a metal reflector layer, but this is not a requirement. In addition, a typical thickness of the core reflector layer is in the range between 30 and 200 nm.

  A pair of layers that are symmetrical may be present on both sides of the reflector layer 100, ie, the reflector layer 100 is such that the reflector layer 100 is sandwiched between the pair of first layers. It may have another first layer disposed opposite to one layer 110. In addition, another second layer 120 and a third layer 130 may be disposed on the opposite side of the reflector layer 100 such that a seven-layer structure is provided. Thus, it should be understood that the discussion of multilayer laminates provided herein also includes the possibility of mirror image construction to one or more central layers. Thus, FIG. 13 can be a half view of a seven-layer multilayer laminate.

In contrast to the embodiment discussed above, the first layer 110 may be an absorber layer, for example a semiconductor absorber layer having a thickness of between 5 and 500 nm, including the lower limit upper limit, and The second layer may be a dielectric absorber layer having a thickness of between 5 and 500 nm, including the lower limit. The semiconductor absorber layer 110 may be made of amorphous Si or Ge, and the dielectric absorber layer 120 may be made of Fe ₂ O ₃ . The semiconductor absorber layer 110 and the dielectric absorber layer 120 generally absorb electromagnetic radiation such that wavelengths less than 550-575 nm have a reflectivity of less than 10-15%, as shown in FIG. You may The third layer 130 is a reflection of wavelengths generally in excess of 575-600 nm, corresponding to a hue between 0-40 °, preferably between 10-30 °, on the a ^* b ^* Lab color space map The high refractive index dielectric layer may have a thickness to obtain In addition, the saturation for the reflection band of visible light is more than 70, preferably more than 80, more preferably more than 90 or more. The reflection spectrum of a multilayer stack as shown in FIG. 13 and having the layer thicknesses listed in Table 1 below is graphically illustrated in FIG. 14 for viewing angles of 0 ° and 45 °. As shown in the figure, the shift of the central wavelength is less than 50 nm, preferably less than 30 nm, and even more preferably less than 20 nm. In addition, it is understood that the UV side of the reflection band is also a very small shift. Taken together with the width of the bands in the visible spectrum, the shift of the reflection band between angles of 0 and 45 ° corresponds to a color change not perceived by the human eye.

FIG. 15 shows absorption versus wavelength for the design shown in FIG. As shown in this figure, multilayer stack 10 absorbs more than 80% of the visible light spectrum at wavelengths up to approximately 550 nm. In addition, embodiment 10 absorbs more than 40% of all wavelengths up to about 610 nm. Thus, the combination of the semiconductor absorbing layer 110, the dielectric absorber layer 120 and the dielectric layer 130 has a hue between 0 and 40 °, preferably between 10 and 30 ° on the a ^* b ^* Lab color space Provide a visible reflection band, i.e., reflection wavelengths in the red spectrum.

  A graphical representation of the case of aspect 10 as a function of percent reflectance, reflected wavelength, and viewing angle is shown in FIG. As shown in this 3D contour plot, at wavelengths between 400 and 550 nm and at observation angles between 0 and 45 to 50, the reflectivity is very low, ie less than 20%. However, at a wavelength of approximately 600 nm, a sharp rise in the percent reflectance is seen.

Another method or technique for describing the omnidirectional properties of the multilayer laminate of the present invention disclosed herein is a plot of saturation and hue versus viewing angle, as shown in FIG. FIG. 17 shows the reflection characteristics of the embodiment shown in FIG. 13, where the hue for angles between 0 and 45 ° is between 20 and 30, and its change or shift is less than 10 ° is there. In addition, the saturation is between 90 and 100 for all viewing angles between 0 and 45 °, where the saturation (C ^* ) is

And a ^* and b ^* are coordinates on the Lab color space or map to the color reflected by the multilayer stack when exposed to broadband electromagnetic radiation, exemplified by white light.

FIG. 18 shows or plots the hue of the embodiment shown in FIG. 13 on an a ^* b ^* Lab color space map (see data points indicated by arrows). Also shown on the map is the region between 15 and 40 °. It is understood that these two points are as indicated for the case of an observation angle of 0 ° with respect to the direction perpendicular to the outer surface of the multilayer stack. In addition, it is also understood that the hue for the embodiment shown in FIG. 13 does not deviate from the 15-40 ° hue region at an observation angle of 0-45 °. In other words, these embodiments exhibit a low hue shift, for example a shift of less than 30 °, preferably less than 20 °, and even more preferably less than 10 °. Still further, it is understood that the embodiment shown in FIG. 13 may be designed such that a single band of visible light having a hue between 0 and 40 degrees is provided and can be plotted on FIG. Preferably a single band of visible light having a hue of between 10 and 30 °.

  Referring now to FIG. 19, a process for producing an omnidirectional high chroma red structured color is schematically illustrated at 20. Process 20 includes dry depositing a reflective core layer at step 202, and subsequently dry depositing a semiconductor absorber layer on the dry deposited reflective core layer at step 210. Then, in step 220, a dielectric absorber layer is dry deposited or wet deposited on the semiconductor absorber layer. Thereafter, at step 230, a high refractive index dielectric layer is wet deposited on the dry deposited semiconductor absorber layer. It is understood that steps 210 and 220 may be repeated to create additional layers on the dry deposited reflective core layer. In addition, a dry deposited reflective core layer may be deposited on the semiconductor absorber layer as well as a wet deposited dielectric layer.

The non-exhaustive list of airlaid n _h dielectric layer and / or wet n _h outer proactive layer (outer proactive layer) is made to be material, shown in Table 1 below.

The above examples and embodiments are for the purpose of illustration only, and alterations, modifications, and the like will be apparent to those skilled in the art and still be included within the scope of the present invention. Accordingly, the scope of the present invention is defined by the claims and all equivalents thereof.
The present invention further includes the following embodiments:
<Aspect 1>
Reflective core layer;
A semiconductor absorber layer extending across the reflective core layer;
A multilayer stack comprising: a dielectric absorber layer extending across the semiconductor absorber layer; and a high refractive index dielectric layer extending across the dielectric absorber layer;
The multilayer stack reflects a single band of visible light having a hue between 0-40 ° on the a ^* b ^* Lab color map, the single band of visible light being of the multilayer stack. Having a hue shift within the range of 0 to 40 ° on the a ^* b ^* Lab color map when viewed from all angles between 0 to 45 ° perpendicular to the outer surface,
All directions high chroma red structure color.
<Aspect 2>
The omnidirectional high saturation red according to 1, wherein the hue is between 10-30 ° and the hue shift is within the range of 10-30 ° on the a ^* b ^* Lab color map. Structure color.
<Aspect 3>
The omnidirectional high chroma red structural color according to 1, wherein the reflective core layer has a thickness of between 50 and 200 nanometers, including the lower limit upper limit.
<Aspect 4>
3. An omnidirectional high saturation red structural color according to claim 3, wherein said reflective core layer is made of a reflective metal selected from the group consisting of Al, Ag, Pt, Sn, and combinations thereof.
<Aspect 5>
3. An omnidirectional highly saturated red structural color according to claim 3, wherein said reflective core layer is made of a colored metal selected from the group consisting of Au, Cu, brass, bronze and combinations thereof.
<Aspect 6>
The omnidirectional high chroma red structural color according to 2, wherein the semiconductor absorber layer has a thickness of between 5 and 500 nanometers including the lower limit and the upper limit.
<Aspect 7>
The omnidirectional high chroma red structural color according to 6 above, wherein the semiconductor absorber layer is made from the group consisting of amorphous Si, Ge, and combinations thereof.
<Aspect 8>
The omnidirectional high saturation red structure color according to the above 6, wherein the dielectric absorber layer has a thickness of between 5 and 500 nanometers including the upper and lower limits.
Aspect 9
8. An omnidirectional high chroma red structured color according to claim 8, wherein said dielectric absorber layer is made of Fe ₂ O ₃ .
<Aspect 10>
The high refractive index dielectric layer has a thickness D according to the relation 0.1QW <D ≦ 4QW, where QW is a quarter-wave thickness to a target wavelength, and the target wavelength is the a ^* b ^{* The} omnidirectional high chroma red structural color according to 6 above, having a predetermined hue within the range of 0-40 ° on the Lab color map.
Aspect 11
The high refractive index dielectric _{layer, ZnS, TiO 2, HfO 2} , Nb 2 O 5, Ta 2 O 5, and is made of a dielectric material selected from the group consisting of, according to the 10 All directions high chroma red structure color.
<Aspect 12>
The reflective core layer is a central reflective core layer, and the semiconductor absorber layer is a pair of semiconductor absorber layers extending over both sides of the central reflective core layer. The omnidirectional highly saturated red structural color of 6, wherein the core layer is sandwiched between the pair of semiconductor absorber layers.
<Aspect 13>
The dielectric absorber layer is a pair of dielectric absorber layers, and the central reflective core layer and the pair of semiconductor absorber layers are sandwiched between the pair of dielectric absorber layers. The omnidirectional high chroma red structural color according to 12 above.
Aspect 14
The high refractive index dielectric layer is a pair of high refractive index dielectric layers, the central reflective core layer, the pair of semiconductor absorber layers, and the pair of dielectric absorber layers are The omnidirectional high saturation red structural color according to the above 13, which is sandwiched between a pair of high refractive index dielectric layers.
Aspect 15
Dry depositing the reflective core layer;
Dry depositing a semiconductor absorber layer extending over the reflective core layer;
Dry or wet depositing a dielectric absorber layer extending across said semiconductor absorber layer; and multi-layer laminate by dry or wet depositing a high refractive index dielectric layer extending across said dielectric absorber layer Including manufacturing
The multilayer stack reflects visible light having a hue between 0 and 40 ° on the a ^* b ^* Lab color map, all between 0 and 45 ° perpendicular to the outer surface of the multilayer stack. Having a hue shift within the range of 0 to 40 ° on the a ^* b ^* Lab color map when viewed from the angle of
Method of manufacturing omnidirectional high chroma red structural color.
Aspect 16
The method according to claim 15, wherein the reflective core layer has a thickness of between 50 and 200 nanometers, including upper and lower limits.
Aspect 17
The method according to claim 16, wherein the reflective core layer is made of a reflective metal selected from the group consisting of Al, Ag, Pt, Sn, and combinations thereof.
<Aspect 18>
The method according to claim 16, wherein the reflective core layer is made of a colored metal selected from the group consisting of Au, Cu, brass, bronze, and combinations thereof.
<Aspect 19>
The method according to claim 16, wherein the semiconductor absorber layer has a thickness of between 5 and 500 nanometers, including the lower limit and is made from the group consisting of amorphous Si, Ge, and combinations thereof.
<Aspect 20>
The method according to claim 16, wherein the dielectric absorber layer has a thickness of between 5 and 500 nanometers, including upper and lower limits, and is made of Fe ₂ O ₃ .

Claims (14)

Reflective core layer;
A semiconductor absorber layer extending across the reflective core layer and in direct contact with the reflective core layer;
A dielectric absorber layer extending across the semiconductor absorber layer and in direct contact with the semiconductor absorber layer; and extending across the dielectric absorber layer and absorbing the dielectric High refractive dielectric layer directly in contact with the body layer;
Comprising a multilayer laminate having
The high refractive index dielectric layer has a thickness D according to the relation 0.1QW <D ≦ 4QW, where QW is a quarter wave thickness to the target wavelength, and the target wavelength is a ^* b ^* Have a predefined hue in the range of 0-40 ° on the Lab color map,
The multilayer stack reflects a single band of visible light having the predetermined hue between 0 and 40 ° on an a ^* b ^* Lab color map, the single band of visible light being the multilayer stack. It has a hue shift of 0 to 40 ° within the predetermined hue range on the a ^* b ^* Lab color map when viewed from all angles between 0 and 45 ° perpendicular to the outer surface of the body ,
Omnidirectional high chroma red structured color pigment. The whole of claim 1, wherein the predetermined hue is between 10 and 30 ° and the hue shift is within the range of 10 to 30 ° on the a ^* b ^* Lab color map. Direction high chroma red structural color pigment.   The omnidirectional high chroma red structured color pigment according to claim 1 or 2, wherein the reflective core layer has a thickness of between 50 and 200 nanometers.   The omnidirectional high chroma red structured color pigment according to any one of claims 1 to 3, wherein the reflective core layer is made of at least one of a reflective metal and a colored metal.   The reflective metal is selected from at least one of Al, Ag, Pt, Sn, Cr, and a combination thereof, and the colored metal is Au, Cu, brass, bronze, and a combination thereof 5. The omnidirectional high chroma red structured color pigment according to claim 4, selected from at least one of them.   The omnidirectional high chroma red structured color pigment according to any one of the preceding claims, wherein the semiconducting absorber layer has a thickness of between 5 and 500 nanometers.   The omnidirectional highly saturated red structural color pigment according to any one of the preceding claims, wherein the semiconducting absorber layer is made from the group consisting of amorphous Si, Ge and combinations thereof.   The omnidirectional high chroma red structured color pigment according to any one of claims 1 to 7, wherein the dielectric absorber layer has a thickness of between 5 and 500 nanometers. It said dielectric absorber layer is made of Fe ₂ O _3, omnidirectional high chroma red structural color pigment according to any one of claims 1-8. The high refractive index dielectric _{layer, ZnS, TiO 2, HfO 2} , Nb 2 O 5, Ta 2 O 5, and is made of a dielectric material selected from the group consisting of combinations, according to claim 1 to 9 An omnidirectional high chroma red structured color pigment according to any one of the preceding claims.   The omnidirectional high chroma red structured color pigment according to any one of claims 1 to 10, wherein the reflective core layer is a dry deposit layer.   The omnidirectional high chroma red structured color pigment according to any one of claims 1 to 11, wherein the semiconductor absorber layer is a dry deposited layer.   The omnidirectional high chroma red structured color pigment according to any one of claims 1 to 12, wherein the dielectric absorber layer is a dry deposited layer or a wet deposited layer.   The omnidirectional high chroma red structured color pigment according to any one of claims 1 to 13, wherein the high refractive index dielectric layer is a dry deposited layer or a wet deposited layer.