KR20230110917A - Optical device including photonic crystal structure, manufacturing method thereof, and method for improving light absorption and light conversion efficiency of optical device - Google Patents

Abstract

One embodiment of the present invention is a phosphor layer having a pattern of a structure protruding periodically on the top surface; and a thin film layer in which a dielectric having a refractive index different from that of the phosphor is deposited on the upper surface of the pattern of the protruding structure, wherein the phosphor layer and the thin film layer form a photonic crystal structure. Provides an optical device. According to one embodiment of the present invention, the interaction between the medium and the incident light is greatly increased by the photonic band edge resonance effect, which is a phenomenon that appears over the entire area of the device in which the micro/nanoscale fine optical structure is formed, so the performance of a large area/high power light emitting device can be improved.

Description

Optical device including photonic crystal structure and method for manufacturing the same, method for improving light absorption rate and light conversion efficiency of optical device

An optical device including the present photonic crystal structure, a method for manufacturing the same, and a method for improving light absorption and light conversion efficiency of the optical device.

Fluorescence is a phenomenon in which a light emitting material absorbs the energy of an excitation photon and emits a photon having a different energy from the absorbed energy. This light conversion phenomenon is applied to various optical devices such as light emitting devices, optical sensors, lasers, and lighting industries, and a method of manufacturing a white LED is representative of active applications in real life.

In particular, a fluorescence phenomenon is used in a dichroic white LED manufactured by forming a light emitting material layer emitting yellow light on an electric driving light-emitting diode (LED) emitting blue light. A portion of the blue light emitted from the blue LED excites the fluorescent material layer to emit yellow light, and as a result, a white LED emitting white light in a wide range of visible light wavelengths can be manufactured. A method of using an LED emitting ultraviolet rays as an excitation light source to excite fluorescent materials emitting red, green, and blue light corresponding to the three primary colors to realize white color is also used in the production of trichromatic white LEDs based on fluorescence. The development direction of the prior art for increasing the light conversion efficiency of a fluorescent material has focused only on changing the chemical properties of the fluorescent material itself.

In addition, research on methods of improving light absorption efficiency and light conversion efficiency by structural design of photonic crystals continues, but according to the prior art, since it is not easy to set a large thickness of the phosphor, there is a problem that the intensity of fluorescence is limited because the amount of light absorbed is small.

The present invention has been made to solve the above problems, and one embodiment of the present invention provides an optical device.

In addition, another embodiment of the present invention provides a method for improving light absorption and light conversion efficiency of an optical element.

In addition, another embodiment of the present invention provides a method of manufacturing an optical element.

The technical problem to be achieved by the present invention is not limited to the technical problem mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

As a technical means for achieving the above-described technical problem, one aspect of the present invention,

a phosphor layer having a pattern of a structure protruding periodically on an upper surface; and a thin film layer in which a dielectric having a refractive index different from that of the phosphor is deposited on the upper surface of the pattern of the protruding structure, wherein the phosphor layer and the thin film layer form a photonic crystal structure. Provides an optical device.

The photonic crystal structure may be characterized in that at least one selected from the period, diameter, and height of the pattern of the protruding structure of the phosphor layer is adjusted so that the wavelength of light from the excitation light source becomes a wavelength corresponding to a photoband edge resonance mode in the photonic band structure of the photonic crystal structure.

The phosphor may include at least one of quantum dots, ceramic material phosphors, and organic dyes.

The quantum dots are 0-dimensional semiconductor nanoparticles, and may include at least one of cadmium selenide (CdSe), cadmium selenide/zinc sulfide (CdSe/ZnS), cadmium telluride (CdTe), and cadmium sulfide (CdS).

The ceramic material phosphor may be selected from Y ₂ O ₃ :Eu, Y ₂ O ₃ :Tb, SrGa ₂ S ₄ :Eu, YAG:Ce, ZnS:Mn, CMS:Eu, BAM:Eu, ZnS:AgAl, and ZnS:CuAl.

The organic dye may include rhodamine or fluorescein.

The dielectric may be characterized in that it includes a nitride or an oxide.

The nitride may include silicon nitride (Si ₃ N ₄ ) or gallium nitride (GaN).

The oxide may include at least one of SiO ₂ , TiO ₂ , ZnO, Al ₂ O ₃ , Ta ₂ O ₅ , HfO ₂ and ZrO ₂ .

The thickness of the phosphor layer may be characterized in that it is 100 nm or more and 100 μm or less.

The optical element may further include a substrate, and the phosphor layer may be provided on the substrate.

The substrate may be transparent in ultraviolet and visible light wavelength bands, and may include at least one of quartz, silicon dioxide (SiO ₂ ), and sapphire (Al ₂ O ₃ ).

Another aspect of the present invention is,

a phosphor layer having a pattern of a structure protruding periodically on an upper surface; and a thin film layer in which a dielectric material having a refractive index different from that of the phosphor is deposited on the upper surface of the pattern of the protruding structure, wherein the phosphor layer and the thin film layer form a photonic crystal structure. A method for improving absorption rate and light conversion efficiency is provided.

Another aspect of the present invention is,

forming a sol solution containing a phosphor material in a patterned mold; forming a phosphor film; forming a phosphor layer having a pattern of periodically protruding structures by transferring the sol solution onto the phosphor film; removing the mold from the phosphor layer having the pattern of the structure protruding periodically from the upper surface of the phosphor film; and depositing a thin film layer including a dielectric material having a refractive index different from that of the phosphor layer on the phosphor layer to form a photonic crystal structure composed of the phosphor layer and the thin film layer.

The mold may be at least one selected from PDMS, glass, and Si, and may be a stamp copied from a master stamp.

The thin film layer may be formed by a physical vapor deposition process (PVD) such as one selected from the group consisting of atomic layer deposition (ALD), chemical vapor deposition (CVD), or sputtering, thermal evaporation, and e-beam evaporation.

Forming the phosphor film; may be characterized in that the phosphor film is provided on a substrate.

According to an embodiment of the present invention, according to an embodiment of the present invention made as described above, an optical element capable of improving the excitation photon absorption rate and the light conversion efficiency of a phosphor due to the photonic band edge effect of a photonic crystal and a manufacturing method of the optical element can be implemented.

In addition, since the phosphor can be formed with a wide thickness, the amount of absorbed light is increased, thereby maximizing the light absorption and light conversion efficiency of the optical element.

The effects of the present invention are not limited to the above effects, and should be understood to include all effects that can be inferred from the description of the present invention or the configuration of the invention described in the claims.

1 is a diagram schematically showing the structure of an optical device according to an embodiment of the present invention.
2 is a flowchart illustrating a method of manufacturing an optical device according to an embodiment of the present invention.
3 is a diagram showing the strength of an electromagnetic field in a photonic crystal region of an optical device according to an embodiment of the present invention.
4 is a diagram illustrating an absorption spectrum analysis result of an optical element according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail. However, the present invention can be implemented in many different forms, and the present invention is not limited by the embodiments described herein, and the present invention is only defined by the claims to be described later.

In addition, terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In the entire specification of the present invention, 'include' a certain element means that other elements may be further included without excluding other elements unless otherwise stated.

Throughout the specification, when a part is said to be "connected (connected, contacted, coupled)" with another part, this includes not only the case of being "directly connected" but also the case of being "indirectly connected" with another member interposed therebetween. In addition, when a part "includes" a certain component, it means that it may further include other components without excluding other components unless otherwise stated.

Terms used in this specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

The first aspect of the present application is,

a phosphor layer having a pattern of a structure protruding periodically on an upper surface; and a thin film layer in which a dielectric having a refractive index different from that of the phosphor is deposited on the upper surface of the pattern of the protruding structure, wherein the phosphor layer and the thin film layer form a photonic crystal structure. Provides an optical device.

Hereinafter, the optical device according to the first aspect of the present disclosure will be described in detail. 1 is a diagram schematically showing the structure of an optical device according to an embodiment of the present invention. Referring to FIG. 1, the photonic crystal fluorescent film includes a phosphor layer 1 structured in the form of a photonic crystal and a thin film layer 2 having a refractive index different from that of the phosphor layer 1.

The optical element according to one embodiment of the present application may have a structure including only a phosphor layer and a thin film layer without a separate substrate, as shown in FIG. 1, and in another embodiment, the optical element may further include a substrate, and the phosphor layer 1 may be provided on the substrate. The above can be applied to all of the first to third aspects of the present application.

In one embodiment of the present application, when a substrate (not shown) is included, the substrate may include, but is not limited to, a base material that is transparent in ultraviolet and visible light wavelength bands, and the substrate may include, for example, quartz, silicon dioxide (SiO ₂ ) and sapphire (Al ₂ O ₃ ).

In one embodiment of the present application, the phosphor layer may include a phosphor. The phosphor 12 may include at least one of quantum dots, ceramic phosphors, and organic dyes.

In one embodiment of the present application, the quantum dots are zero-dimensional semiconductor nanoparticles, and may include at least one of cadmium selenide (CdSe), cadmium selenide/zinc sulfide (CdSe/ZnS), cadmium telluride (CdTe), and cadmium sulfide (CdS).

In one embodiment of the present application, the ceramic material phosphor may be selected from Y ₂ O ₃ :Eu, Y ₂ O ₃ :Tb, SrGa ₂ S ₄ :Eu, YAG:Ce, ZnS:Mn, CMS:Eu, BAM:Eu, ZnS:AgAl, and ZnS:CuAl.

In one embodiment of the present application, the organic dye may include rhodamine or fluorescein.

In one embodiment of the present application, the thickness of the phosphor layer may be set without limitation in consideration of the size, area, optical performance, etc. of a product requiring an optical element. The thickness of the phosphor layer may be 100 nm or more, 250 nm or more, 500 nm or more, 5 μm or more, 10 μm or more, or 15 μm or more, 200 μm or less, 150 μm or less, 100 μm or less, 90 μm or less, or 80 μm or less. If the thickness is less than the above-mentioned range, sufficient light absorption may not be achieved, and if it exceeds the above-mentioned range, it will not be preferable in terms of thinning of the product. In particular, in the case of the optical device according to one embodiment of the present application, it may be characterized in that light absorption and light conversion efficiency can be maximized because a large thickness phosphor can be applied while being able to utilize the optical band edge effect.

In one embodiment of the present application, the phosphor layer may have a pattern of a structure that protrudes periodically on an upper surface.

In an embodiment of the present application, in the photonic crystal structure according to the wavelength of light from the excitation light source, at least one selected from the period, diameter, and height of the pattern of the protruding structure of the phosphor layer can be adjusted so that the wavelength of the light from the excitation light source becomes a wavelength corresponding to the gamma point photonic band edge resonance mode in which the lateral component of the wavenumber k in the photonic band structure of the photonic crystal structure is 0.

In one embodiment of the present application, the period and diameter of the pattern of the protruding structure of the phosphor layer may be set in consideration of the relationship with the light wavelength of the light source to maximize the photonic band edge effect. For example, the period of the pattern of the protruding structure of the phosphor layer may be 200 to 500 nm, or 250 to 450 nm. Also, preferably, the diameter of the pattern of the protruding structure of the phosphor layer may be 200 to 500 nm, or 250 to 450 nm, and the diameter of the pattern of the protruding structure of the phosphor layer may be the same as or partially different from the period (separation distance).

In one embodiment of the present application, the optical element may include a thin film layer in which a dielectric material having a refractive index different from that of the phosphor layer is deposited on an upper surface of the pattern of the protruding structure of the phosphor layer.

In one embodiment of the present application, the dielectric may be characterized in that it includes a nitride or an oxide. The nitride may include silicon nitride (Si ₃ N ₄ ) or gallium nitride (GaN).

Also, in one embodiment of the present application, the oxide may include at least one of SiO ₂ , TiO ₂ , ZnO, Al ₂ O ₃ , Ta ₂ O ₅ , HfO ₂ and ZrO ₂ .

The second aspect of the present application is,

a phosphor layer having a pattern of a structure protruding periodically on an upper surface; and a thin film layer in which a dielectric material having a refractive index different from that of the phosphor is deposited on the upper surface of the pattern of the protruding structure, wherein the phosphor layer and the thin film layer form a photonic crystal structure. A method for improving absorption rate and light conversion efficiency is provided.

Detailed descriptions of portions overlapping with those of the first aspect of the present application have been omitted, but the contents described for the first aspect of the present application can be equally applied even if the description is omitted from the second aspect.

Hereinafter, a method for improving light absorption and light conversion efficiency of an optical element according to a second aspect of the present disclosure will be described in detail.

The photonic crystal refers to a structure in which two or more materials having different refractive indices are arranged in periodicity. Depending on the direction of the periodicity, there are three types of photonic crystal structures: one-dimensional, two-dimensional, and three-dimensional. The photonic crystal has a unique photonic band structure representing a dispersion relation between a photon frequency (ω) and a wave vector according to the refractive index and period of the constituent material.

In addition, a photonic band-gap wavelength band in which photons having a wavelength of a specific band cannot propagate in at least one specific crystal direction may exist within a photonic band structure for a specific photonic crystal structure. The optical bandgap characteristics of the photonic crystal can be used to construct subminiature optical devices such as optical cavities and optical waveguides.

On the other hand, in the photonic band-edge wavelength band corresponding to the boundary of the photonic band-gap wavelength band, the group velocity of photons passing through the inside of the photonic crystal structure approaches 0, and there is a photonic band-edge effect characteristic in which the interaction between the photon and the material constituting the photonic crystal structure increases. The above two optical properties can be applied to the development of various optical devices.

Therefore, as described above, the photonic crystal structure has a unique photonic band structure along the direction of the period, and in particular, the photonic crystal structure may have a photonic band gap in at least one specific crystal direction. That is, the photonic crystal structure may have photonic band gap and photonic band edge characteristics in a specific wavelength band. The photonic bandgap and the wavelength band of the photonic band edge may be determined by the thickness and period of the photonic crystal structure pattern and the refractive index of each material (substrate, phosphor, and dielectric).

For example, when a phosphor is excited with excitation photons having the photonic bandedge wavelength band, the group velocity of the excitation photons may approach 0 inside the photonic crystal structure due to the photonic bandedge effect. At this time, energy can be more effectively transferred to the dielectric and phosphor constituting the photonic crystal structure. Here, the photon may be emitted from an external excitation source of the optical device, and the external excitation source may include a light emitting diode (LED) or a laser diode (LD) emitting light in a range of ultraviolet or blue light wavelength bands. However, the incident direction of the excitation photon (L_exc) is not limited to the direction depicted in FIG. 1, and may be incident in a direction opposite to that depicted.

In addition, the absolute value of the electromagnetic wave function representing the distribution probability of the excitation photon may appear remarkably high in a region where a photonic crystal structure exists. More specifically, for efficient coupling between the photonic bandedge resonance mode of the photonic crystal structure and the excitation photon, the wavenumber vector of the photonic bandedge resonance mode and the traveling direction of the excitation photon may coincide.

On the other hand, as exemplified above, in order for the wave number vector of the photonic crystal structure, which is in the form of a pattern with periodicity in the transverse direction, to coincide with the propagation direction of the excitation photon, the direction of the wave number vector of the photonic crystal structure must be in the vertical direction (thickness direction of the substrate) perpendicular to the photonic crystal structure. Here, the periodicity of the pattern of the protrusion structure in the transverse direction may be, for example, about 1 micron or less, 750 nm or less, 600 nm or less, 550 nm or less, or 500 nm or less.

Therefore, since the optical element according to an embodiment of the present invention includes a photonic crystal structure, the absorption rate in the optical band edge wavelength band is relatively higher than that of the optical element having a single-layer structure, thereby improving the luminous efficiency of the optical element.

In addition, the excitation source may be used instead of the substrate of the optical element, and, for example, the same excitation source as the excitation source of the above-described embodiment may be used. That is, it may include a light emitting diode (LED) or a laser diode (LD) emitting light in a range of ultraviolet or blue light wavelengths. By exciting the photonic crystal structure with photons emitted from the excitation source of the optical device, white light can be emitted to the outside. A detailed description of the phosphor and the dielectric is omitted since it is the same as the above description.

The third aspect of the present application,

forming a sol solution containing a phosphor material in a patterned mold; forming a phosphor film; forming a phosphor layer having a pattern of periodically protruding structures by transferring the sol solution onto the phosphor film; removing the mold from the phosphor layer having the pattern of the structure protruding periodically from the upper surface of the phosphor film; and depositing a thin film layer including a dielectric material having a refractive index different from that of the phosphor layer on the phosphor layer to form a photonic crystal structure composed of the phosphor layer and the thin film layer.

Detailed descriptions of portions overlapping with the first and second aspects of the present application have been omitted, but the contents described for the first and second aspects of the present application can be equally applied even if the description is omitted in the third aspect.

Hereinafter, a method for manufacturing an optical element according to a third aspect of the present disclosure will be described in detail with reference to the drawings. 2 is a flowchart illustrating a method of manufacturing an optical device according to an embodiment of the present invention.

First, in one embodiment of the present application, a step (S100) of forming a sol solution containing a phosphor material in a patterned mold may be included.

In one embodiment of the present application, the mold may be, for example, a soft mold made of a polymer material such as PDMS (polymethylsiloxane). In addition, the mold may be a hard mold made of, for example, glass or Si. The soft mold or hard mold may be a replica mold replicated from a master mold having an opposite pattern formed on a surface thereof. At this time, a release layer may be formed on the surface of the master mold, and the release layer may be composed of, for example, PPT (pentaerythritol propoxylate triacrylate) or PUA (polyurethane acrylate). This serves to facilitate separation of the replica mold and the master mold. The periodically protruding phosphor pattern formed in the mold may have an embossed or intaglio pattern. When an embossed pattern is formed, the phosphor layer to which the pattern is transferred may have a hole-type photonic crystal pattern, and when an intaglio pattern is formed, the phosphor layer to which the pattern is transferred may have a dot-type photonic crystal pattern.

In one embodiment of the present application, a spin coating method may be used as a method of forming the sol solution on the mold. Through this, the sol solution can be sufficiently applied to the inside of the pattern of the mold. In addition, rubbing may be performed after the spin coating so that the sol solution is uniformly applied on the mold.

Next, in one embodiment of the present application, forming a phosphor film (S200) may be included. The step of forming the phosphor film (S200) may be characterized in that the phosphor film is provided on a substrate, and in another embodiment, the phosphor film is formed on a temporary substrate without a substrate as a stand-alone structure. All may be included.

In one embodiment of the present application, the phosphor film may be deposited with a thickness of a micron or sub-micron unit.

In one embodiment of the present application, the composition of the phosphor should basically conform to stoichiometry, and each element may be substituted with another element in each group on the periodic table. For example, strontium (Sr) can be replaced with alkaline earth (II) group barium (Ba), calcium (Ca) or magnesium (Mg), and yttrium (Y) can be replaced with lanthanide group terbium (Tb), ruthenium (Lu), scandium (Sc) or gadolinium (Gd). In addition, Eu, etc., which is an activator, can be substituted with cerium (Ce), terbium (Tb), preseodymium (Pr), erbium (Er), or ytterbium (Yb), etc., depending on the desired energy level, and an activator alone or an auxiliary activator may be additionally applied to modify properties.

In one embodiment of the present application, the coating method of the phosphor film may be largely one of a method of spraying an LED chip or a light emitting element, a method of covering in the form of a film, or a method of attaching a sheet form such as a film or ceramic phosphor. Dispensing, spray coating, etc. are common as spraying methods, and dispensing includes mechanical methods such as pneumatic methods and screw and linear types. It is also possible to control the dotting amount through the jetting method and the color coordinates through this. A method of collectively applying phosphors at a wafer level or on a head substrate by a spray method has an advantage in that productivity and thickness control can be easily performed. The method of directly covering the light emitting element or LED chip in the form of a film may be applied by electrophoresis, screen printing, or molding of a phosphor, and may have a difference in the method depending on whether or not the side of the LED chip is coated.

In addition, in one embodiment of the present application, in order to control the efficiency of a long-wavelength light-emitting phosphor that re-absorbs light emitted at a short wavelength among two or more types of phosphors having different light-emitting wavelengths, two or more types of phosphor films having different light emission wavelengths may be distinguished, and a DBR layer may be included between each layer to minimize re-absorption and interference of two or more types of wavelengths between the LED chip and the phosphor. In addition, in order to form a uniform coating film, the phosphor may be produced in the form of a film or ceramic and then attached to the LED chip or light emitting element. In order to give a difference in light efficiency and light distribution characteristics, a light conversion material may be positioned in a remote form, and at this time, the light conversion material may be positioned together with a material such as a light-transmitting polymer or glass according to durability and heat resistance.

Next, in one embodiment of the present application, a step of forming a phosphor layer having a pattern of a periodically protruding structure by transferring the sol solution onto the phosphor film may be included (S300).

In one embodiment of the present application, as described above, the mold on which the sol solution is formed is brought into contact with the phosphor film, and the sol solution is transferred to the upper surface of the phosphor film through a heating and press process. At this time, the heating temperature may be within the range of 100 ℃ to 200 ℃, pressurization conditions may be within the range of 1 atm to 20 atm. At this time, a solvent such as ethanol or water included in the sol solution 40a may be removed. The transfer process may be performed in a vacuum state.

In one embodiment of the present application, the photonic crystal structure in the transverse direction of the substrate or the excitation source, that is, the thickness and period of the pattern of the periodically protruding structure can be easily determined according to the constituent material and the wavelength band of the excitation light source to be optimized.

Next, in one embodiment of the present application, a step of removing the mold from the phosphor layer having a pattern of a structure that periodically protrudes from the upper surface of the phosphor film (S400) may be included.

In one embodiment of the present application, by lowering the temperature, it is possible to form a pattern of a structure that periodically protrudes on the phosphor film by separating the mold and the phosphor film that are in contact as described above.

Next, a thin film layer including a dielectric material having a refractive index different from that of the phosphor layer may be deposited on the phosphor layer to form a photonic crystal structure composed of the phosphor layer and the thin film layer (S500).

In one embodiment of the present application, the thin film layer may be characterized in that it is performed by a physical vapor deposition process (PVD) method such as one selected from the group consisting of an atomic layer deposition process (ALD), a chemical vapor deposition process (CVD), or sputtering, thermal evaporation, and e-beam evaporation. Preferably, the formation of the thin film layer including the dielectric may be performed by a chemical vapor deposition process (CVD). In the case of the chemical vapor deposition process (CVD), the thin film is deposited through a plasma enhanced chemical vapor deposition (PECVD) process suitable for miniaturization and low temperature in the surface treatment of metals or polymers. It is more preferable to form.

The optical element according to one embodiment of the present application can be used for various purposes in various industrial fields where a combination of a light source and a fluorescent material is used, such as a light emitting element, a display element, LED lighting, and a micro LED field.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

Example 1: Photonic crystal structure fabrication

In all unit cells, quartz or silicon dioxide (SiO ₂ ) was used as a substrate, and a phosphor layer having a thickness of about 60 to 70 μm was formed on the substrate. A cellulose acetate polymer solution doped with rhodamine 6G organic dye was used as a material for the phosphor layer, and the phosphor layer was deposited by spin coating. A phosphor material was applied to a PDMS mold patterned with a periodic lattice structure and transferred onto the deposited phosphor film to form a phosphor layer. Looking at the structure of the patterns, the separation distance (period) between the patterns was 330 nm, the average height of each pattern was 150 nm, and the diameter was about 120 nm. In addition, when looking at the planar shape of the patterns, it was found that they had a shape consistent with the patterning shape of PDMS. After this, a thin film containing a dielectric was deposited to a thickness of 25 nm by sputtering, where the material of the dielectric was TiO ₂ .

In addition, all unit cells were excited using a blue-based excitation light source in which the central wavelength of excitation photons corresponds to a band of about 440 nm.

Comparative Example 1: Optical element including only phosphor layer

An optical device was manufactured in the same manner as in Example 1, except for forming only the phosphor layer on the substrate and subsequently patterning and depositing a thin film including a dielectric.

Comparative Example 2: Optical element including a phosphor layer and a dielectric layer without a pattern

An optical element was manufactured in the same manner as in Example 1, except for the process of forming only the phosphor layer on the substrate and smoothly depositing the dielectric layer on the phosphor layer.

Experimental Example 1: Analysis of Light Absorption Efficiency Characteristics

3 is a diagram showing the intensity of an electromagnetic field in a photonic crystal region of an optical device according to an embodiment of the present application, and FIG. 4 is a diagram showing an absorption spectrum analysis result of an optical device according to an embodiment and comparative examples of the present application.

First, referring to FIG. 3, looking at the result of computational simulation of the electromagnetic field intensity in the optical band edge resonant wavelength band in the unit cell of the optical device according to the experimental example of the present invention, it can be confirmed that the electromagnetic field intensity is strong in the one-dimensional photonic crystal structure region. More specifically, the characteristics of the photonic bandedge resonance mode can be quantified by a standardized Q-factor whose calculation method is widely known. The lower the value of the Q-factor, the more favorable the coupling between the photon outside the structure and the electromagnetic field mode inside the structure.

Referring to FIG. 4, when the photonic crystal thin film structure is included in the unit cell of the optical device, the unit cell 100a of the optical device, that is, the periodic protruding structure, the absorption rate in the optical band edge wavelength band of the unit cell of the optical device is several times higher than the absorption rate in the phosphor monolayer structure (Comparative Example 1) or the dielectric layer without phosphor and pattern (Comparative Example 2). When the period of the photonic crystal pattern is about 330 nm, 360 nm, 390 nm, and 420 nm, the optical band edge wavelength bands optimized by the excitation photons correspond to about 440 nm, 480 nm, 520 nm, and 560 nm, respectively.

As described above, in the embodiment of the present invention, as a measure of the degree of efficient excitation of the fluorescent material, the result of calculating the absorption by the imaginary refractive index or absorption coefficient of the fluorescent material is simulated and presented using the finite difference time domain (FDTD) method.

On the other hand, by comparing the absorption spectra of each of the patterned photonic crystal structures proposed in the present invention with the case of coating in the form of a simple uniform single-layer thin film made of only fluorescent materials using a conventional technique, it is possible to predict the increase in the absorption rate of excitation photons and the light conversion efficiency of the phosphor due to the photonic band edge effect of the photonic crystal thin film structure. In particular, efficient excitation can occur when the direction of the wave vector of the photonic band edge resonance mode is perpendicular to the surface of the thin film and coincides with the traveling direction of external excitation photons.

The above description of the present invention is for illustrative purposes, and those skilled in the art may understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims (17)

a phosphor layer having a pattern of a structure protruding periodically on an upper surface; and
A thin film layer in which a dielectric material having a refractive index different from that of the phosphor is deposited on the upper surface of the pattern of the protruding structure;
An optical device, characterized in that the phosphor layer and the thin film layer form a photonic crystal structure.
According to claim 1,
The photonic crystal structure is such that the wavelength of light from the excitation light source is a wavelength corresponding to the photonic band edge resonance mode in the photonic band structure of the photonic crystal structure.
An optical element, characterized in that at least one selected from period, diameter, and height of the pattern of the protruding structure of the phosphor layer is adjusted.
According to claim 1,
The optical element includes at least one of a quantum dot, a ceramic material phosphor, and an organic dye.
According to claim 3,
The quantum dots are zero-dimensional semiconductor nanoparticles, and include at least one of cadmium selenide (CdSe), cadmium selenide/zinc sulfide (CdSe/ZnS), cadmium telluride (CdTe), and cadmium sulfide (CdS). An optical element.
According to claim 3,
The ceramic material phosphor is selected from Y ₂ O ₃ :Eu, Y ₂ O ₃ :Tb, SrGa ₂ S ₄ :Eu, YAG:Ce, ZnS:Mn, CMS:Eu, BAM:Eu, ZnS:AgAl, and ZnS:CuAl.
According to claim 3,
The organic dye includes rhodamine (rhodamine) or fluorescein (fluorescein), an optical element.
According to claim 1,
The optical element, characterized in that the dielectric comprises a nitride or oxide.
According to claim 7,
The nitride is characterized in that it comprises silicon nitride (Si ₃ N ₄ ) or gallium nitride (GaN), the optical device.
According to claim 7,
The oxide may include at least one of SiO ₂ , TiO ₂ , ZnO, Al ₂ O ₃ , Ta ₂ O ₅ , HfO ₂ and ZrO ₂ .
According to claim 1,
The optical element, characterized in that the thickness of the phosphor layer is 100nm or more and 100μm or less.
According to claim 1,
The optical element further includes a substrate,
An optical element, characterized in that the phosphor layer is provided on the substrate.
According to claim 11,
The substrate is transparent in ultraviolet and visible light wavelength bands, and includes at least one of quartz, silicon dioxide (SiO ₂ ) and sapphire (Al ₂ O ₃ ), an optical element.
a phosphor layer having a pattern of a structure protruding periodically on an upper surface; and
A thin film layer in which a dielectric material having a refractive index different from that of the phosphor is deposited on the upper surface of the pattern of the protruding structure;
As a method for improving light absorption and light conversion efficiency of an optical element, characterized in that the phosphor layer and the thin film layer form a photonic crystal structure,
A method for improving light absorption and light conversion efficiency of an optical device, wherein light having a wavelength corresponding to the photonic band edge resonance mode in the photonic crystal structure is used as an excitation photon to excite the phosphor to increase light absorption and light conversion efficiency.
forming a sol solution containing a phosphor material in a patterned mold;
forming a phosphor film;
forming a phosphor layer having a pattern of periodically protruding structures by transferring the sol solution onto the phosphor film;
removing the mold from the phosphor layer having the pattern of the structure protruding periodically from the upper surface of the phosphor film; and
depositing a thin film layer including a dielectric material having a refractive index different from that of the phosphor layer on the phosphor layer to form a photonic crystal structure composed of the phosphor layer and the thin film layer;
Including, a method for manufacturing an optical element.
According to claim 14,
The method of manufacturing an optical element, characterized in that the mold is at least one selected from PDMS, glass and Si, and is a stamp copied from a master stamp.
According to claim 14,
The thin film layer is formed by an atomic layer deposition process (ALD), a chemical vapor deposition process (CVD), or a physical vapor deposition process (PVD) such as one selected from the group consisting of sputtering, thermal evaporation, and e-beam evaporation.
According to claim 14,
Forming the phosphor film;
A method for manufacturing an optical element, characterized in that the phosphor film is provided on a substrate.