KR20190028142A - The structural color filter using multicavity resonances - Google Patents

Abstract

According to the present invention, it is possible to provide a structural color filter having low angle dependency, high efficiency, high purity, and high transmittance. In the structural color filter of the present invention, RGB can be adjusted depending on the thickness of the semiconductor layer.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a structure color filter using multi-cavity resonance,

The present invention relates to a color filter, and more particularly, to a color filter having a low dependence on an incident angle using multi-cavity resonance and exhibiting high purity and high transmission characteristics at the same time.

Color filters are used in various fields such as liquid crystal display technology, optical measurement systems, light emitting diodes, CMOS image sensors and the like. However, color filters based on organic dyes and chemical pigments have been mainly used. Since dyes and pigments are sensitive to continuous ultraviolet radiation, high temperature and humidity, organic dyes and chemical pigments (pigments) ) Has a problem that the performance of the color filter is deteriorated rapidly. In addition, in order to reduce the pixel size in such a conventional color filter, a complex and highly accurate alignment process is necessarily required.

In order to solve the above-mentioned problems of color filters based on conventional organic dyes and chemical pigments, a structural color filter has received a lot of attention in recent years. Such structured color filters have the potential to achieve high efficiency, high resolution, small pixel size, long term stability and nonphotobleaching. In order to trigger one of the photon resonance mode and the plasmon resonance mode, the structure color filter mainly utilizes the nanostructure of silver (Ag) or gold (Au) having a width less than the wavelength of visible light. Ag and Au have a lower optical absorption loss in the visible light spectrum as compared with other metals.

However, there is a problem that Ag or Au is not only applicable to current CMOS manufacturing methods, but also expensive. In addition, a structural color filter using Ag or Au has a problem of showing poor performance efficiency and remarkable color degradation with time. The gold material causes an interband transition of the Au material at 468 nm, and the Ag material is oxidized or sulfided. In addition, realizing performance characteristics that are insensitive to the angle of incidence of light in color generation is also one of the problems to be solved.

In order to achieve such angular non-sensitive performance characteristics, various structure color filters have been proposed. However, many complicated lithographic processes were required, and the use of optical interference effects on lossy materials not only greatly reduced efficiency, but also efficiency and color purity tradeoffs, resulting in high efficiency At the same time, it is difficult to obtain a high-purity structural color filter, and therefore, a method for improving such a problem is needed.

It is an object of the present invention to provide a structural color filter having a low degree of angle dependency and high efficiency, high purity and high permeability.

The structure color filters for one purpose of the present invention include first to third metal layers spaced apart from one another and arranged sequentially; A first semiconductor layer disposed between the first metal layer and the second metal layer; And a second semiconductor layer disposed between the second metal layer and the third metal layer.

In one embodiment, the first to third metal layers may include silver (Ag).

In one embodiment, the thickness of the metal layer may be between 10 nm and 50 nm.

In one embodiment, the first and second semiconductor layers may comprise zinc sulphide (ZnS).

In one embodiment, the light emitting device may further include a first antireflection layer disposed on the first metal layer and a second antireflection layer disposed under the third metal layer.

In one embodiment, the first and second semiconductor layers include zinc sulfide (ZnS), and the first and second anti-reflection layers may include zinc sulfide (ZnS).

In one embodiment, the thickness of the first antireflection layer and the second antireflection layer may be 40% to 60% of the thickness of the first and second semiconductor layers.

In one embodiment, the first to third metal layers and the first and second semiconductor layers may be stacked on a flexible substrate.

In one embodiment, RGB may be implemented by adjusting the thickness of the first and second semiconductor layers.

In one embodiment, the first and second semiconductor layers include zinc sulfide (ZnS), and red when the thickness of the first and second semiconductor layers is 95 nm to 115 nm, respectively.

In one embodiment, the first and second semiconductor layers comprise zinc sulfide (ZnS), and may be green when the thickness of the first and second semiconductor layers is 60 nm to 80 nm, respectively.

In one embodiment, the first and second semiconductor layers include zinc sulfide (ZnS), and may exhibit blue when the thickness of the first and second semiconductor layers is 30 nm to 50 nm, respectively.

According to the present invention, first to third metal layers which are spaced apart from each other and arranged sequentially; A first semiconductor layer disposed between the first metal layer and the second metal layer; And a second semiconductor layer disposed between the second metal layer and the third metal layer, the first antireflection layer disposed on the first metal layer and the second antireflection layer disposed under the third metal layer The structure color filter of the present invention exhibits high efficiency, high purity, and high transmittance, and RGB can be realized by adjusting the thickness of the semiconductor layer. Further, since the structure color filter of the present invention does not require a complicated manufacturing process, it can be easily applied in various fields.

1 and 2 are diagrams illustrating a structure color filter according to an embodiment of the present invention.
FIGS. 3 to 19 are views showing the result of analyzing the structure color filter according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the term "comprises" or "having ", etc. is intended to specify that there is a feature, step, operation, element, part or combination thereof described in the specification, , &Quot; an ", " an ", " an "

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, embodiments of the present invention will be described in detail. However, the following examples are only a few embodiments of the present invention, and the present invention should not be construed as being limited to the following examples.

1 is a diagram illustrating a structure color filter according to an embodiment of the present invention. 1, a structural color filter 100 according to an exemplary embodiment of the present invention includes a substrate 200, a first metal layer 310, a second metal layer 320, a third metal layer 330, Layer 410, a second semiconductor layer 420, a first antireflection (AR) layer 510, and a second antireflection layer 520.

The structure color filter 100 includes a second antireflection layer 510, a first metal layer 310, a first semiconductor layer 410, a second metal layer 320, a second semiconductor layer 420, The third metal layer 330, and the first antireflection layer 520 may be stacked. In other words, the structure color filter 100 includes first to third metal layers 310, 320 and 330 spaced apart from each other, a first semiconductor layer 310 disposed between the first metal layer 310 and the second metal layer 320, And a second semiconductor layer 420 disposed between the second metal layer 320 and the third metal layer 330. The first semiconductor layer 310 may include a first antireflection layer 520 and a third anti-reflection layer 510 disposed under the third metal layer 330.

The material and structure of the substrate 200 are not particularly limited as long as they can stably support the metal layers 310, 320, and 330 and the semiconductor layers 410 and 420. For example, the substrate 150 may be a glass substrate, an insulating polymer substrate, a semiconductor substrate, or the like, or may be a flexible substrate.

At this time, ZnS, which is a wide bandgap semiconductor material having a high refractive index with a negligible light absorptivity in the visible light region, can be included in the semiconductor layer as an optical medium, and Ag, which exhibits the highest reflectance and the lowest light absorption rate in the visible light wavelength range, And can be used as a metallic mirror. That is, the structure color filter may be composed of a plurality of thin film layers in which a semiconductor layer and a metal layer are alternately repeated and laminated. In other words, the first to third metal layers 310, 320, and 330 may include metals having high reflectance and low light absorption characteristics. For example, silver (Ag), gold (Au), or aluminum (Al), and may be a thin film type Ag layer made only of Ag. The first and second semiconductor layers 410 and 420 may include a semiconductor material having a high refractive index, for example, a thin film ZnS layer made of only ZnS.

The structure color filter of the present invention may include, for example, a structure in which an Ag layer and a ZnS layer are alternately repeatedly stacked, and may include a structure in which an Ag layer and a ZnS layer are stacked in a vertically symmetrical manner. Zn layer, an Ag layer, an Ag layer, an Ag layer, a Zn layer, an Ag layer, an Ag layer, an Ag layer, a Zn layer, and an Zn layer Layer-Ag layer.

On the other hand, when a plurality of Fabry-Perot resonances are generated at almost the same position of the visible wavelengths in the two ZnS layers in the structure color filter shown in Fig. 1, a specific portion of visible light is selectively And it can be controlled according to the thickness of the first and second semiconductor layers 410 and 420.

In one embodiment, the thickness of the first to third metal layers 310, 320 and 330 may be between 10 nm and 50 nm.

The first antireflection layer 520 and the second antireflection layer 510 may include zinc sulfide (ZnS), and the thicknesses of the first antireflection layer 520 and the second antireflection layer 510 may be, respectively, 2 < / RTI > semiconductor layers 410 and 420, respectively. For example, the first antireflection layer 520 and the second antireflection layer 510 may be in the form of a film made of ZnS having a thickness of about 50% of the first and second semiconductor layers 410 and 420.

The first antireflection layer 520 and the second antireflection layer 510 may mitigate reflection at the interface between the first and third metal layers 310, 320, and 330 and the air or glass. Therefore, the structure color filter 100 of the present invention can be improved in transmittance by the first antireflection layer 520 and the second antireflection layer 510.

The first to third metal layers 310, 320 and 330, the first and second semiconductor layers 410 and 420 and the first and second antireflection layers 520 and 510 are formed by E-beam evaporation ) Evaporator on a substrate.

In one embodiment, the structural color filter of the present invention may comprise a second antireflection layer-a first metal layer-a first semiconductor layer-a second metal layer-a second semiconductor layer-a third metal layer-a first antireflection layer, The lower antireflection layer-Ag layer-ZnS layer-Ag layer-ZnS layer-Ag layer-upper antireflection layer.

2 is a diagram illustrating a structure color filter according to an embodiment of the present invention. 2 illustrates a structural color filter according to an embodiment of the present invention fabricated on a glass substrate (3 × 3 cm ² ). Referring to FIG. 2, The optical image shows that the background is vividly transmitted through the structured color filter. The structure color filter according to the embodiment can have a unique RGB color and the background can be clearly seen through the structure color filter. On the other hand, since the complicated lithography process is not required to manufacture the structural color filter of the present invention having such characteristics, it can be easily applied to various display devices of a wider size and can be applied to a flexible substrate.

By adjusting the thicknesses of the first and second semiconductor layers of the structure color filter according to an embodiment of the present invention, RGB can be realized as shown in FIG.

For example, when the thicknesses of the first and second first and second semiconductor layers are independently 95 nm to 115 nm and the thicknesses of the first to third metal layers are independently 20 nm to 40 nm, .

In another embodiment, the thicknesses of the first and second semiconductor layers are independently 60 nm to 80 nm, and the thicknesses of the first to third metal layers are each independently 25 nm to 45 nm. .

In another embodiment, the thickness of the first and second semiconductor layers may be independently from 30 nm to 50 nm, and the thickness of each of the first to third metal layers may be blue to 20 nm to 40 nm independently have.

In one embodiment, the first to third metal layers and the first and second semiconductor layers may be stacked on a flexible substrate.

FIGS. 3 to 19 are views showing the results of analyzing the characteristics of the structural color filter according to an embodiment of the present invention. For example, the first to third metal layers are spaced apart from one another and are sequentially arranged. A first semiconductor layer disposed between the first metal layer and the second metal layer; And a second semiconductor layer disposed between the second metal layer and the third metal layer, the first antireflection layer disposed on the first metal layer and the second antireflection layer disposed under the third metal layer The results are shown in Fig.

Specifically, FIG. 3 shows the transmission simulated spectroscopic curve (a) and the actually measured spectroscopic curve (b) for incident light perpendicularly incident on the structured color filter of the present invention. Referring to FIG. 3, the thickness of each of the first and second semiconductor layers and the first to third metal layers is 104 nm and 32 nm (red), 70 nm and 34 nm (green), and 40 nm and 28 nm Blue, and blue, respectively, wherein the first antireflection layer 520 and the second antireflection layer 510 may have a thickness of about half the thickness of the first and second semiconductor layers, (E. G., 52 nm, 35 nm and 20 nm, respectively). Fig. 3 (a) is a vertical incidence transmission simulation spectral curve, and it can be confirmed that it substantially coincides with Fig. 3 (b) showing the actually measured spectral curve. 3 (a) and (b) both show a double peak in the transmission spectroscopy curve.

Specifically, FIG. 4 shows a CIE 1931 color space chromaticity diagram of the color coordinates calculated from the spectral curves shown in FIG. 3, and the color purity can be confirmed. Referring to FIG. 4, the color coordinates (x, y) calculated from the simulation results (black circles) and the actual measurement results (black squares) shown in FIG. 3 are compared with the color space . The color coordinates of the actual measured color space for each RGB color were red (0.641, 0.324), green (0.355, 0.527) and blue (0.156, 0.136) (0.353, 0.520) and blue (0.155, 0.412). Referring to FIG. 4, since the color gamut of the color filter of the present invention is wide, it can be seen that a color filter capable of displaying a wide range of colors can be produced by using the structure color filter of the present invention. It can be confirmed that the transmittance can be not less than 60% even when the off-resonance wavelength component, which is essential for achieving high color purity, is greatly suppressed, as well as in the case of having a significantly high slope (i.e., high Q-factor). The color purity can be further improved by shifting the resonance to a short (or long) wavelength of blue (or red) and increasing the thickness of the first to third metal layers.

Specifically, FIG. 5 shows a comparison of one embodiment of the structure color filter. 5, the dotted line shows the simulation transmission spectral curve of the structural color filter composed of the Ag layer-ZnS layer-Ag layer, and the solid line shows the ZnS layer-Ag layer-ZnS layer-Ag layer-ZnS layer-Ag- The transmission spectral curve of the structure color filter is shown. Referring to FIG. 5, the solid line indicating the structure color filter composed of the ZnS layer-Ag layer-ZnS layer-Ag layer-ZnS layer-Ag-ZnS layer does not affect the sharpness of the resonance and color purity It can be seen that it exhibits remarkably improved luminance. The solid line at this time is the same curve as shown in Fig. 3 (a). ZnS or Ag can each be used to produce red, green and blue (RGB) in the structured color filter, and the antireflective layer can comprise ZnS and can be half the thickness of the ZnS layer constituting the structural color filter. For example, if the thicknesses of the ZnS and Ag layers are 104 nm and 32 nm, 70 nm and 34 nm or 40 nm and 28 nm, respectively, then the antireflective layer will have a thickness of 52 nm, 35 nm or 20 nm .

 Transmission spectroscopy (transmission spectrum) was measured with a spectrometer (V-770 UV-Visible-Near Infrared Spectrophotometer, JASCO). Optical simulation was performed based on the transfer matrix method to evaluate vertical incidence angles, angular decomposition transmission spectroscopy curves, and the strength of the electric field. The refractive index of the Ag layer and ZnS layer was measured with a spectroscopic ellipsometer (Elli-SE, Ellipso Technology Co.) and used for optical simulation.

The simulated transmission spectroscopy curve for blue exhibits only one resonance peak with an efficiency of 63.49% at 430 nm, whereas the actual measured transmission spectroscopy shows two peaks with efficiencies of 52.14% and 34.51% at 395 nm and 474 nm, respectively And exhibits a relatively broad spectrum. This difference is caused by the fact that the absorption coefficient of ZnS used in simulation modeled by ellipsometry may be somewhat higher than the absorption coefficient of ZnS in actual color filter manufacturing. From the simulation results, can do. The broad resonance behavior with low transmission efficiency in the measured spectroscopic curves compared to the simulated spectroscopic curves can be seen as the thinner Ag thickness in the manufactured color filters. This may result in a reduced reflection effect and hence a weaker interference effect. On the other hand, in the simulation, the green resonance showed 70.85% and 55.37% efficiency at 508 nm and 574 nm, and the red case showed 71.93% and 50.29% efficiency at 652 nm and 737 nm, The efficiencies of 65.05% and 49.85% are shown at 517 nm and 582 nm, respectively, and the red colors are almost the same as 67.42% and 48.48% efficiency at 655 nm and 741 nm, respectively.

The blocking capabilities of the structured color filter of the present invention can be represented by optical density (OD), which is a degree of attenuation of light energy, when passing through a color filter. ) Is used. Where T is the transmittance.

(1)

(One)

When the OD value calculated through the calculation formula is low, it means that the degree of attenuation of the light energy is low, which indicates that the transmission is good.

Specifically, FIG. 6 shows the OD values of the RGB colors of the structural color filter of the present invention obtained from the transmission simulation spectral curve and the measured transmission spectral curve of the present invention. The lower the OD value, the higher the transmittance And a higher OD value indicates a lower transmittance. Referring to FIG. 6, although it shows a low OD value at the resonant wavelengths, it is confirmed that the OD value is high at the off resonance wavelength with respect to the RGB colors. Therefore, the structure color filter of the present invention shows a high transmittance. As a result of comparing the performance of the structure color filter of the present invention with the performance of a commercially available dichroic color filter depending on the optical interference effect of the multilayer thin film structure, A higher transmittance can be exhibited. This is because, in the case of a dichroic color filter, the metal layer having light absorption properties does not affect the color filter. However, the dichroic color filter is very sensitive to the incident angle, and the structural color filter of the present invention exhibits a wide-angle performance, so that the structural color filter of the present invention can be more usefully used.

Fig. 7 shows the transmission spectroscopic curves of the simulations for comparison of the presence or absence of the antireflection layer. The simulated transmission spectroscopic curves in green were compared for each case with no antireflection layer and antireflection layer. Referring to FIG. 7, the black, blue, red, and green lines from below indicate the case where there is no antireflection layer at both the top and bottom, only the bottom antireflection layer, only the top antireflection layer, (For example, Ag layer-ZnS layer-Ag layer-ZnS layer-Ag layer) in the case of the black line, and the lowest transmission efficiency of less than about 40% even in the resonance . In the case of the red line and the blue line, strong reflection may occur at the interfaces of Ag and air or glass, and the transmittance may be low. On the other hand, in the case of a green line indicating a symmetrical antireflection layer (for example, an antireflection layer including an antireflection layer-Ag layer-ZnS layer-Ag layer-ZnS layer-Ag layer-ZnS including ZnS) While exhibiting high transmittance and exhibiting high efficiency and high purity color. By arranging the antireflection layers symmetrically, the reflection at the upper and lower interfaces between Ag and air or glass is remarkably relaxed and the transmittance is improved.

Specifically, Figure 8 shows a computed 2D contour plot of a structured color filter (510 nm) showing green with both top and bottom antireflective layers as the transmittance change for the refractive index and film thickness variations of the antireflective layer will be. Considering that the refractive index of ZnS is about 2.37 at 510 nm, the optimized thickness was about 35 nm. Although the thickness of the antireflective layer can be reduced by using a material having a refractive index greater than 2.5, lossless materials exhibiting such a high refractive index are difficult to find, and ZnS and titanium dioxide (TiO ₂ ) can be used. The effect of the antireflective layer is shown using an optical admittance diagram showing the surface admittance change of the entire structure from the substrate to the incident medium.

The optical admittance (Y) is the reciprocal of the impedance, and a fine magnetic effect in the visible frequency range can affect the optical admittance to be equal to the square root of the permittivity (i.e., the refractive index). Impedance can be expressed using the following equation (2). Where μ is the transmittance and ε is the permittivity.

(2)

(2)

The optical characteristics of the structured color filter of the present invention can be visually represented as an admittance locus in a complex plane. Although the optical admittance of a lossless dielectric layer and a perfect electrical conductor shows a simple circular trajectory, the admittance trajectories of metals and semiconductors appear spirally due to light absorption. The optical admittance of the structured color filter starts at one point on the substrate and can change the admittance trajectory of both the film thickness and optical properties. The discrepancy between the ending point of the multilayer structure and the admittance (1, 0) of the air indicates how large the reflection occurs in the entire structure. This minimizes the difference between the endpoint and the admittance of the air, thus confirming that the reflection is relaxed.

The reflectance can be expressed by the following equation (3). Where Y _i and Y _t are the admittance at the incident medium and at the end points.

(3)

(3)

9 shows an optical admittance diagram according to the presence or absence of an antireflective layer at 510 nm (green). FIG. 9-1 shows the case where there is no antireflection layer, and FIG. 9-2 shows the case where there is an antireflection layer . 9, the end point (4.65, -1.03) indicated by the red dot of the optical admittance is largely different from the admittance (1, 0) of the air in the case of the absence of the antireflection layer (9-1) (1.08, -0.21) indicated by red dots are not significantly different from the admittances (1, 0) of air in the case where the antireflection layer is present on both the upper and lower sides (9-2) Was about 1.12%.

Specifically, FIG. 10 (a) shows the transmission spectroscopic curve of the simulation for comparing the presence or absence of the antireflection layer of the present invention in the blue color, and for each case with the antireflection layer and the antireflection layer, Were compared. The black, blue, red, and green lines indicate structures with no antireflective layer at the top and bottom, with only the bottom antireflective layer, with only the top antireflective layer, and with both antireflective layers at the top and bottom. 10 (b) shows a calculated 2D contour plot of the structure color filter showing blue with both top and bottom antireflective layers at 425 nm as the transmittance change for the refractive index and film thickness variation of the antireflective layer. 10 (c) and 10 (d) show an optical admittance diagram according to the presence or absence of the antireflection layer at 425 nm. (C) shows a high reflectance of 49.27% without the antireflection layer, The reflectance of 1.62% was confirmed in the case where the antireflection layer was present on both the top and bottom.

Specifically, FIG. 11 (a) shows a simulation transmission spectroscopic curve for comparing the presence or absence of the antireflection layer of the present invention in red, and in each case of the absence of the antireflection layer and the antireflection layer, a simulation transmission spectral curve Respectively. The black, blue, red, and green lines indicate structures with no antireflective layer at the top and bottom, with only the bottom antireflective layer, with only the top antireflective layer, and with both antireflective layers at the top and bottom. Figure 11 (b) shows a calculated 2D contour plot of the structural color filter showing the red color with the antireflective layer both at the top and bottom at 650 nm as the transmittance change for the refractive index and film thickness variation of the antireflective layer. 11 (c) and 11 (d) show an optical admittance diagram in accordance with the presence or absence of the antireflection layer at 425 nm. (C) shows a high reflectance of 56.52% in the absence of the antireflection layer, When the reflection preventing layer was present on both the top and bottom, a low reflectance of 4.39% was confirmed.

The influence of the thicknesses of the first to third metal layers, the first and second semiconductor layers, and the first and second anti-reflection layers 520 and 510 was confirmed through an evaluation example.

Specifically, FIG. 12 shows the simulation transmission spectral curves (a (a), (a), and (b)) according to the thicknesses of the first and second semiconductor layers by fixing the thicknesses of the first to third metal layers ), A normal incidence transmission spectroscopic curve (b) according to the thicknesses of the first to third semiconductor layers, and the thicknesses of the first and second semiconductor layers (for example, 40 nm of the ZnS layer) (C) shows the color coordinates calculated from the transmission spectroscopic curves shown in Figs. 12 (a) and 12 (b) in the CIE 1931 chromaticity diagram. 12 (a) and 12 (b), it was confirmed that as the thickness of the first and second semiconductor layers (ZnS layers) decreases, the resonance moves to a shorter wavelength region, It can be seen that as the thickness of the two semiconductor layers, that is, the ZnS layer, decreases, wavelengths of 500 nm or more can be reflected instead of being transmitted. At shorter wavelengths, the optical absorption of the ZnS layer reduces the transmission efficiency, but the purity of the color can be further improved. As the thickness of the metallic mirror, that is, the first to third metal layers (for example, the Ag layer) increases, the spectrum appears sharp because the thickness of the metal layers increases and the reflection at the surface increases. 12 (c) showing the color coordinates of each case shown on the diagram, the resonance shift to the shorter wavelength regime and the increase in the thickness of the metal layers both improve the color purity. Can be seen. On the other hand, the color space of the 35 nm thick Ag layer (in this case, the ZnS layer thickness of 40 nm) and the 28 nm thick ZnS layer (in this case, the Ag layer thickness of 28 nm) 0.150, 0.063) and (0.160, 0.063), respectively. In both cases, it can be seen that it is quite similar to the standard color space (0.150, 0.060) for blue of the liquid crystal display device.

Specifically, FIG. 13 shows an analysis result according to the thickness of the first and second semiconductor layers and the first to third metal layers with respect to green in normal incidence, wherein the thickness (for example, 34 nm) of the Ag layer is fixed Simulation transmission spectroscopic curve (a) and ZnS layer thickness (for example, 70 nm) are fixed according to the thickness of the ZnS layer, and the vertical incidence transmission spectroscopic curve (b) according to the thickness of the Ag layer is shown. (C) shows the color coordinates calculated from the transmission spectroscopic curves shown in Figs. 13 (a) and 13 (b) in the CIE 1931 chromaticity diagram. Referring to FIG. 13, it can be seen that resonance effects are strongly exhibited as the thickness of the Ag layer increases. The color space of the 42 nm thick Ag layer (here, the thickness of the ZnS layer is 70 nm) was calculated to be (0.325, 0.606). In both cases, the standard color space for green of the liquid crystal display device (0.300, 0.600), so that the color purity is excellent. However, by changing the thickness of the ZnS layer resonance changes can occur, which can increase the difference from the standard green color. 13 (c), the color coordinates (black triangle) of a 64 nm thick ZnS layer (in this case, the thickness of the Ag layer is 34 nm) is calculated as an example of the thickness reduced to 70 nm As a result, a slight shift to the blue region (0.258, 0.429) and an increase in thickness over 70 nm are shown by the color coordinates (black asterisk) of the 76 nm thick ZnS layer (in this case, the Ag layer thickness is 34 nm) (0.426, 0.533), which was slightly shifted to the yellow region. Such a difference may occur because, by reducing or increasing the thickness of the ZnS layer in the structured color filter of the present invention, relatively shorter wavelength components or longer wavelength components can be included in the spectral characteristics.

Specifically, FIG. 14 shows an analysis result according to the thickness of the first and second semiconductor layers and the first to third metal layers with respect to red in normal incidence, wherein the thickness (for example, 32 nm) of the Ag layer is fixed The simulation transmission spectroscopic curve (a) according to the thickness of the ZnS layer, the thickness of the ZnS layer (for example, 104 nm) and the vertical incidence transmission spectroscopic curve (b) according to the thickness of the Ag layer are shown, (C) shows the color coordinates calculated from the transmission spectroscopic curves shown in Figs. 14 (a) and 14 (b) in the CIE 1931 chromaticity diagram. Referring to FIG. 14, a transmission spectroscopic curve for red shows a second resonance peak in a short wavelength range. 14 (a), the secondary resonance seems to increase as the thickness of the ZnS layer is increased, and the color purity may also decrease as shown in Fig. 14 (c). The color coordinates (black color) of the structure using the 116 nm thick ZnS layer (the Ag layer thickness is 32 nm) is (0.443, 0.181) and shows magenta color. 14 (b), it can be seen that secondary resonance is reduced as the thickness of the Ag layer is increased, and that the graph appears in a more sharp shape, and FIG. 14 (c) Together, it can be seen that the color purity is not lowered in this case. As a result of the calculation of the color space, the 38 nm thick Ag layer (here, the ZnS layer thickness was 104 nm) (0.689, 0.297), and the standard color space for the red color of the liquid crystal display device was 0.640, 0.330).

15 (a) to 15 (c) illustrate electric field intensity distributions of the structure color filter according to an embodiment of the present invention. Referring to FIGS. 15 (a) to 15 (c) It can be seen that there are two regions in the ZnS layer (2 ^nd ZnS and 3 ^rd ZnS) where the electric field is concentrated at slightly unequal wavelengths. This is because the structure of the color filter structure is not perfectly symmetrical, and resonance appears at the slightly shifted wavelength. The strong optical field in the ZnS layer is related to the resonance in the visible region and is thus related to the high transmittance for color generation. FIG. 15 (d) shows the net phase shifts calculated by dividing the second (solid line) and third (dotted line) middle ZnS layers by 2π as a function of wavelength, and shows the positions of the main resonance mode and the second resonance mode . As a result of comparison, it can be seen that the two ZnS layers show a similar phase change. As shown in FIG. 15 (a), the main resonance wavelength of blue is 374 nm and 461 nm in the second middle ZnS layer and 410 nm in the third middle ZnS layer, all of which strongly increase the electric field in the middle ZnS layer It coincides well with the position where it is. This resonance also coincides with the transmission spectroscopy curve shown in Fig. 3 (a). In the case of green, the resonance obtained from the phase change calculation appeared at 508 nm and 590 nm of the second intermediate ZnS layer, and at 514 nm and 582 nm of the third intermediate ZnS layer, (a). < tb >< TABLE > Similarly, in the case of red, it appears to occur at 652 nm and 746 nm in the second intermediate ZnS layer, and at 659 nm and 737 nm in the third intermediate ZnS layer.

The structure color filter according to an embodiment of the present invention can be easily manufactured even on a flexible substrate because it can be manufactured only through a deposition process. The RGB color filter of the present invention was fabricated on a plastic substrate (for example, polyethylene terephthalate (PET)) to confirm the optical performance according to the banding deformation.

Specifically, FIGS. 16A and 16B show the transmittance and the position of the resonance wavelength with respect to the RGB color as a function of the radius of curvature, and show a large change in transmittance and resonance for the radius of curvature up to 10 mm And when the radius of curvature was 5 mm, the maximum value of the transmittance was reduced by about 1% to 5% while maintaining the resonance position. The transmission spectroscopic curves measured at different curvature radii are shown in FIG. 16 (d) (the curvature radius is 80 nm, the large dotted line is 40 nm, and the small dotted line is 5 nm) . FIG. 16 (c) shows the multi-banding evaluation result, and it can be confirmed that the maximum transmittance of the green filter does not change even in the evaluation of the banding of 3,000 times.

17, it can be seen that blue, green, and red are well represented even when the structural color filter is bent, and it can be seen that the background of each of the filters showing each color is clearly transmitted.

The characteristics of the inventive structural color filters shown in Figures 16 and 17 potentially mean that various practical applications such as flexible optoelectronic devices, electronic paper displays and wearable electronic devices are possible.

If a relatively high refractive index material is used, the refraction of the structure can be reduced when the light enters the structure at an oblique incident angle according to Snell's law. The refractive index of the measured ZnS is about 2.4 at 600 nm and can be seen to be high enough to reduce the angle dependent properties.

Specifically, Figures 18 (a) to 18 (c) show the simulation angle-decomposition transmission spectroscopy curves, resonance does not change at an incident angle of 70 ° or more in p-polarized light illumination, . FIGS. 18 (d) to 18 (f) show the actually measured angular-decomposition transmission characteristics, which can be seen to be in good agreement between the simulation results and the actual measured values. It can be seen that both the top and bottom antireflective layers can function as a phase compensation layer and thus all may affect angle-insensitive properties.

19 is a view showing a comparative example according to the structure difference of the structure color filter according to an embodiment of the present invention. 18A is a graph showing a change in transmittance according to whether an antireflection layer (in this case, ZnS) is introduced or not of a structural color filter laminated with an Ag layer-ZnS layer-Ag layer when the metal layer is an Ag layer and the semiconductor layer is a ZnS layer . When no antireflection layer was present, it was shown as dark green. When the antireflection layer was present in both the upper and lower portions, it was shown as bright fluorescent green. As a result of comparison, it can be confirmed that the transmittance increases by introducing the antireflection layer in both the upper and lower portions even in the case of the structure in which the Ag layer, the ZnS layer and the Ag layer are stacked. However, since the width of the transmission spectroscopic curve is increased, have. 19B shows the transmission spectroscopic curves of the Ag layer-ZnS layer-Ag layer-ZnS layer-Ag layer, which can broaden the transmission spectroscopy curve, but the transmittance is low and the Ag layer-ZnS Layer-Ag layer-ZnS layer-The Ag transmission layer can be increased by stacking an antireflection layer on the upper or lower side of the Ag layer. In addition, when the reflective layer is introduced into both the upper and lower portions, the transmittance can be greatly increased, and unlike the case of the Ag layer-ZnS layer-Ag layer, there is no additional line width change and the decrease in color purity can be suppressed.

In terms of the performance of the color filter, the smaller the width of the transmission spectroscopic curve, the higher the color purity in terms of color purity. However, it may be difficult to increase the brightness of the backlight in order to increase the brightness. In this regard, it should be possible to export as much light as possible within a high purity wavelength range, and thus be used as an excellent color filter. Therefore, as the spectral curve having a width and a steep slope in which the high color purity can be realized has a high transmittance, the ZnS layer-Ag layer-ZnS layer-Ag layer-ZnS layer- In the case of the structural color filter including the structural color filter laminated with the Ag-ZnS layer, the best effect can be obtained.

The structured color filter of the present invention can generate color with high efficiency in the visible light region by using interaction of light and structure, instead of generating color based on pigment coloring. Therefore, it can be maintained even longer in chemical processes and long-lasting illumination, high color production efficiency, high stability, easy scalability, high resolution, nonphotobleaching, fidelity for reproducibility, slim dimensions and can be expressed in planar thin-film structures, in surface plasmon resonances in nanocavities in nanostructures, in guided-mode resonances in subwavelengths in subwavelength waveguide nanostructures waveguide nanostructures, and photonic crystals.

Through the present invention, it is possible to provide a wide-angle transmission structure color filter using multiple resonance of a structure color filter composed of dielectric media and alternating layers of optically thin metal films. The structured color filter of the present invention can exhibit an optimized antireflection coating effect of an optimized antireflection layer by including an in a symmetric configuration and can achieve a significantly improved transmittance without significantly degrading color purity . In particular, when a material having a high refractive index in the visible light range is present in the antireflection layer, the angle dependent property is significantly reduced to have a wide acceptance angles range of 70 ° or more. As a result, it can be seen that the refractive index of the cavity medium having a high refractive index is reduced.

On the other hand, since the structural color filter of the present invention can be manufactured through a simple thin film deposition method, it can be mass-produced and applied to various application fields. Furthermore, since a structural color filter can be manufactured only by simple vapor deposition without using an expensive and complicated lithography method, it can be easily introduced with a flexible platform, and a structural color filter according to an embodiment of the present invention can be manufactured on a plastic substrate As a result of checking the bending deformation effect, the optical properties are almost unchanged after 5 mm bending radius condition and over 3,000 banding evaluations, thus expanding the possibilities for more diverse research fields . Thus, the inventive structure color filters can be used in a variety of research fields such as displays, anticounterfeiting tags, light modulators, colored solar cells and chemical sensors, .

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims. It can be understood that it is possible.

Claims (12)

First to third metal layers spaced apart from each other and arranged sequentially;
A first semiconductor layer disposed between the first metal layer and the second metal layer; And
And a second semiconductor layer disposed between the second metal layer and the third metal layer,
Structure color filter.
The method according to claim 1,
Characterized in that the first to third metal layers comprise silver (Ag)
Structure color filter.
3. The method of claim 2,
Wherein each of the first to third metal layers has a thickness of 10 nm to 50 nm.
Structure color filter.
The method according to claim 1,
Characterized in that the first and second semiconductor layers comprise zinc sulphide (ZnS)
Structure color filter.
The method according to claim 1,
Further comprising a first antireflection layer disposed on the first metal layer and a second antireflection layer disposed under the third metal layer.
Structure color filter.
6. The method of claim 5,
Wherein the first and second semiconductor layers comprise zinc sulphide (ZnS)
Wherein the first and second anti-reflective layers comprise zinc sulphide (ZnS).
Structure color filter.
The method according to claim 6,
Wherein the thickness of the first and second anti-reflection layers is 40% to 60% of the thickness of each of the first and second semiconductor layers.
Structure color filter.
The method according to claim 1,
Wherein the first to third metal layers and the first and second semiconductor layers are stacked on a flexible substrate.
Structure color filter.
The method according to claim 1,
And the thickness of the semiconductor layers is adjusted to realize RGB.
Structure color filter.
10. The method of claim 9,
Wherein the first and second semiconductor layers comprise zinc sulphide (ZnS)
Wherein the first semiconductor layer and the second semiconductor layer exhibit a red color when the thickness of the first and second semiconductor layers is 95 nm to 115 nm, respectively.
Structure color filter.
10. The method of claim 9,
Wherein the first and second semiconductor layers comprise zinc sulphide (ZnS)
Wherein the first and second semiconductor layers exhibit green when the thickness of the first and second semiconductor layers is 60 nm to 80 nm, respectively.
Structure color filter.
10. The method of claim 9,
Wherein the first and second semiconductor layers comprise zinc sulphide (ZnS)
Wherein the first and second semiconductor layers exhibit blue when the thickness of the first and second semiconductor layers is 30 nm to 50 nm, respectively.
Structure color filter.

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