WO2018139866A1 - Micro led, and display device including same - Google Patents

Abstract

The present specification provides a micro LED, and a display device including the same, the micro LED comprising: a micro LED chip; and an organic dye layer formed on the micro LED chip, wherein the organic dye layer contains one or more types of organic dyes.

Description

Micro LED and display device including same

This application claims the benefit of the filing date of Korean Patent Application No. 10-2017-0012617 filed with the Korea Intellectual Property Office on January 26, 2017, the entire contents of which are incorporated herein.

The present specification relates to a micro LED and a display device including the same.

LED is a device that converts electrical energy into light energy by using the semiconductor characteristics of compounds. Recently, the size of LED chips has been reduced to micro size to overcome the disadvantages of bending due to the characteristics of inorganic materials. Is being studied as a flexible device material.

In addition, since the micro LEDs drive each pixel separately, there is no need to use a liquid crystal, which is an essential element of the conventional LCD, and thus, there is an advantage that the power consumption can be reduced by minimizing the loss of light generated from the pixels. I am getting it.

Meanwhile, conventionally, since the color purity and luminance of the LED chips generating blue, green, and red light are low, after the use of the blue chip, inorganic phosphors are applied to realize green and red light. However, the inorganic phosphor has a low luminous efficiency and should be used in a large amount, and there is a problem in that a separate reflective layer must be formed inside a separate partition wall to avoid color mixing. On the other hand, organic dyes have various light emission spectra, excellent quantum efficiency, and low cost, which is sufficient for use in devices.

The present specification provides a micro LED and a display device including the same.

One embodiment of the present specification is a micro LED chip; And an organic dye layer formed on the micro LED chip, wherein the organic dye layer provides a micro LED including one or more organic dyes.

In addition, an exemplary embodiment of the present disclosure provides a display device including the micro LED.

Micro LED according to one embodiment of the present specification can reproduce high brightness and high color purity.

Micro LED according to an exemplary embodiment of the present specification may be provided with a diffusion layer, thereby improving durability.

Micro LED according to an exemplary embodiment of the present disclosure can exhibit high brightness and durability by spreading the LED light coming from a small area in a large area.

1 to 5 are diagrams illustrating micro LEDs according to exemplary embodiments of the present specification.

6 to 9 is a view showing the light emission intensity according to the wavelength of the micro LED according to one embodiment of the present specification.

10: micro LED chip

20: organic dye layer

30: diffusion layer

40: color filter

a: blue area

b: green area

c: red area

Hereinafter, this specification is demonstrated in detail.

In the present specification, when a part "includes" a certain component, it means that it may further include other components, without excluding the other components unless otherwise stated.

In this specification, when a member is located "on" another member, this includes not only when one member is in contact with another member, but also when another member exists between the two members.

In the present specification, "LED" may be interpreted as a light emitting diode.

Micro LED according to an embodiment of the present disclosure is a micro LED chip; And an organic dye layer formed on the micro LED chip, wherein the organic dye layer includes one or more organic dyes.

The organic dye layer absorbs light from the LED chip and converts the light from the LED chip into high efficiency, thereby improving color purity and improving brightness.

In one embodiment of the present specification, the thickness of the organic dye layer is 1 μm to 20 μm. When the thickness of the organic dye layer is 1 μm to 20 μm, the effect of color purity improvement and luminance improvement can be obtained. On the other hand, when the thickness of the organic dye layer is less than 1μm, there is a problem that it is difficult to improve the color purity because the number of dyes that can convert the light from the LED chip is insufficient. In addition, when the thickness of the organic dye layer is more than 20μm, there is a problem of color mixing, there is a problem that a metal layer for preventing the color mixing should be formed inside the partition wall.

In general, the inorganic phosphor has a low luminous efficiency and should be used in a large amount, and there is a problem in that a separate reflective layer or a metal layer is formed inside the partition wall in order to avoid color mixing. The partition wall is a transparent pillar having a height of several tens of micrometers formed between the pixels so that light emitted from the R, G, and B pixels does not interfere with each other. In the prior art, after forming a partition wall through photolithography, a metal layer such as aluminum is applied to the inside, thereby emitting light emitted from each pixel to the front side instead of moving to the next pixel.

In contrast, organic dyes have various light emission spectra, excellent quantum efficiency, and low cost, and are easy to use in devices. In addition, when the above-mentioned thickness is satisfied, there is no problem of color mixing, so it is not necessary to form a separate reflective layer or metal layer in the partition wall.

In one embodiment of the present specification, the organic dye includes both an organic fluorescent dye and an organic phosphorescent dye, and an organic metal complex or an organic dye may be used.

In one embodiment of the present specification, the organic dye includes carbon, and means a dye consisting of a nonmetallic element and / or a metalloid element.

In one embodiment of the present specification, the organic dye includes a green phosphor and / or a red phosphor.

In the present specification, the "green phosphor" absorbs at least a portion of blue light to emit green light, and the "red phosphor" absorbs blue light or at least a portion of green light to emit red light. For example, the red phosphor can absorb not only blue light but also light having a wavelength between 500 nm and 600 nm.

In the present specification, the blue light, the green light, and the red light may use definitions known in the art. For example, blue light is light having a wavelength selected from a wavelength of 400 nm to 480 nm, green light is light having a wavelength selected from a wavelength of 500 nm to 570 nm, and red light is light having a wavelength selected from a wavelength of 600 nm to 780 nm. In the present specification, the organic dye may absorb at least a portion of the red light and at least a portion of the green light at the same time. For example, the organic dye may absorb light of a wavelength of 570nm to 600nm.

In an exemplary embodiment of the present specification, the organic dye is a bodypy series, perylene series, acridine series, xanthene series, aryl methane series, coumarin series, pyrrole series, rhodamine series, pyril series, phenoxazone series, stilbene series, ter It contains at least one of phenyl type and quarter phenyl type. Specifically, the organic dye may include a bodypi or perylene dye.

In one embodiment of the present specification, the organic dye layer includes one or two organic dyes described above.

In general, when the organic dye is applied to micro LEDs, there is a problem in that the discoloration or discoloration occurs quickly due to weak durability. On the other hand, the organic dyes used in the present invention, in particular, body-based or perylene-based dyes have a strong durability for LED light, the half width of the emission wavelength is narrow, high color conversion efficiency has the effect of showing high brightness.

In one embodiment of the present specification, the organic dye layer includes two or more organic dyes. When two or more organic dyes are included, color reproducibility may be improved than when one is used.

In an exemplary embodiment of the present specification, the organic dye layer improves both brightness and color reproduction by using a first organic dye having a maximum emission wavelength of relatively short wavelength and a second organic dye having a maximum emission wavelength of relatively long wavelength. can do. For example, by using a first organic dye having a maximum emission wavelength at a wavelength of 480 nm to 540 nm and a second organic dye having a maximum emission wavelength at a wavelength of 600 nm to 780 nm, color reproducibility at 480 nm to 780 nm can be improved. .

In one embodiment of the present specification, when the organic dye layer includes two or more organic dyes, the first organic dye serves to effectively absorb the light of the micro LED, the second organic dye is the first organic dye The light absorbs the light emitted can emit light of high color purity. In this case, the first organic dye may be referred to as a pumping dye.

In one embodiment of the present specification, the organic dye content in the organic dye layer is 0.1 parts by weight to 5 parts by weight relative to 100 parts by weight of the organic dye layer.

When the content of the organic dye satisfies the above range, it may exhibit the effect of improving color purity and improving luminance.

In one embodiment of the present specification, the particle diameter of the organic dye is 0.2nm to 50nm.

In one embodiment of the present specification, the organic dye has a half width at 60 nm or less at an emission peak representing a maximum height.

In the present specification, "half-width" means the width of the luminescence peak when half of the maximum height of the maximum height of the light absorbed and emitted by the organic dye. The smaller the half width of the organic dye is, the better.

In one embodiment of the present specification, the organic dye has a small diameter compared to the size of the inorganic dye, a few μm, high so that the light conversion efficiency is close to 100%, because the width of the light emitting wavelength is small amount Also, high brightness and high color purity can be reproduced.

In one embodiment of the present specification, the organic dye layer includes an organic dye and a binder resin.

In one embodiment of the present specification, the binder resin may be a photocurable resin, a thermosetting resin or a thermoplastic resin. Specifically, the binder resin may be a thermosetting resin and a thermoplastic resin. More specifically, the binder resin is poly (meth) acrylic, polycarbonate, polystyrene, polyarylene, polyurethane, styrene-acrylonitrile, polyvinylidene fluoride, and poly such as polymethyl methacrylate. Vinylidene fluoride derivatives and the like can be used. In addition, the binder resin may be a water-soluble polymer.

In one embodiment of the present specification, the binder resin may be used only one kind, two or more kinds may be used together.

In one embodiment of the present specification, the organic dye layer may further include at least one of a diffusion agent composed of inorganic particles, an antioxidant for preventing oxidation, or a surfactant and a dispersant for improving processability, in addition to the organic dye.

In one embodiment of the present specification, the inorganic particles used as the diffusing agent include metal oxide particles. The metal oxide may be at least one of titanium oxide, zirconium oxide, tin oxide, zinc oxide, niobium oxide, hafnium oxide, indium oxide, and tungsten oxide, but is not limited thereto. Specifically, the inorganic particles may be SiO ₂ , TiO ₂ , ZrO ₂ or SnO ₂ , but is not limited thereto.

In one embodiment of the present specification, the diameter of the inorganic particles used as the diffusion agent is 10nm to 5μm.

In one embodiment of the present specification, when the diffusion agent is used in the organic dye layer, the diffusion agent is dispersed in the organic dye layer is present. Therefore, LED light is more effectively diffused to reach the dye than when the inorganic particles are present zone by zone or when no diffusion agent is included.

In one embodiment of the specification, the method of manufacturing the organic dye layer is not particularly limited as long as it is a method used in the art, for example, to be prepared using a dispensing, bar coating, inkjet, spin coating or screen printing method Can be.

1 illustrates a lamination structure of a micro LED according to an exemplary embodiment of the present specification. Specifically, FIG. 1 illustrates a structure in which the organic dye layer 20 is provided on the micro LED chip 10.

In the present specification, the organic dye layer includes two or more regions having different maximum emission wavelengths.

In the present specification, the organic dye layer includes three regions having different maximum emission wavelengths. For example, the organic dye layer includes a first region having a maximum emission wavelength at a wavelength of 420 nm to 480 nm, a second region having a maximum emission wavelength at a wavelength of 480 nm to 540 nm, and a third having a maximum emission wavelength at a wavelength of 600 nm to 780 nm. It can be composed of areas.

FIG. 2 is a diagram illustrating that the blue region (a), the green region (b), and the red region (c) are divided while the organic dye layer 20 is provided on the micro LED chip 10. The micro LED according to the present specification is not limited to the structure of FIGS. 1 and 2, and further members may be further included.

In one embodiment of the present specification, a diffusion layer may be provided between the micro LED chip and the organic dye layer.

When the diffusion layer is provided, the light emitted from the micro LED chip is effectively scattered, thereby preventing the organic dye from being oxidized or decomposed by the light. In addition, the diffusion layer by spreading the LED light coming from a small area in a large area, the organic dyes of the organic dye layer can be in contact with the LED light evenly to exhibit the effect of improving the brightness and durability.

In one embodiment of the present specification, the diffusion layer exhibits a positive effect opposite to that of the DBR layer in which the light emitted from the micro LED is reflected and directed to the opposite side before reaching the dye by performing the above-described functions.

In one embodiment of the present specification, the diffusion layer includes an inorganic particle and a binder resin.

In one embodiment of the present specification, the inorganic particles in the diffusion layer may be included in 5 parts by weight to 50 parts by weight based on 100 parts by weight of the diffusion layer.

In one embodiment of the present specification, the diffusion layer may have an effect of scattering light by including inorganic particles and a binder resin.

In one embodiment of the present specification, the kind of the binder resin included in the diffusion layer is the same as described above for the organic dye layer.

In one embodiment of the present specification, the type of inorganic particles included in the diffusion layer is the same as described above for the organic dye layer.

In one embodiment of the present specification, the diffusion layer may further include at least one of an organic dye and an inorganic phosphor.

In one embodiment of the present specification, the diffusion layer further includes an organic dye and / or an inorganic phosphor, thereby scattering light and simultaneously absorbing LED light, thereby exhibiting an additional effect of improving luminance.

In the present specification, the type of organic dye included in the diffusion layer is the same as described above for the organic dye layer.

In the present specification, the content of the organic dye in the diffusion layer may be 0.1 to 10 parts by weight based on 100 parts by weight of the diffusion layer.

In the exemplary embodiment of the present specification, the inorganic phosphor may include YAG, SiAlON, Gallium nitride, Silicon carbide, Zinc selenide, GaAlAsP, and the like, but is not limited thereto.

In one embodiment of the present specification, the content of the inorganic phosphor in the diffusion layer may be 1 to 30 parts by weight based on 100 parts by weight of the diffusion layer.

In one embodiment of the present specification, the diffusion layer may be provided entirely on the micro LED chip, or may be provided only in a partial region. For example, the diffusion layer may be provided only in the green and / or red portion of the micro LED chip.

In one embodiment of the present specification, the thickness of the diffusion layer is 100 nm to 10 μm. When the thickness of the diffusion layer satisfies the above range, there is an effect of effectively scattering light emitted from the micro LED chip.

In one embodiment of the present specification, the manufacturing method of the diffusion layer is not particularly limited as long as it is a method used in the art, for example, using a dispensing, bar coating, inkjet printing, sputtering, spin coating or screen printing method Can be prepared.

In one embodiment of the present specification, the diffusion layer may be formed by coating inorganic particles using a sputtering method without using a binder resin.

Figure 3 shows a laminated structure of a micro LED according to an embodiment of the present specification. Specifically, FIG. 3 illustrates a structure in which the diffusion layer 30 is provided on the micro LED chip 10 and the organic dye layer 20 is provided on the diffusion layer 30. The micro LED according to the present specification is not limited to the laminated structure of FIG. 3, and further members may be further included.

In one embodiment of the present specification, the micro LED chip may have the same configuration as the LED chip known in the art. For example, n-type GaN may be positioned below the device reference, and p-type GaN may be positioned directly above.

In one embodiment of the present specification, a color filter may be further included on the organic dye layer. The color filter may be disposed on a path of light emitted from the micro LED.

In the present specification, that the color filter is provided on the organic dye layer means that the color filter is provided on the opposite side of the surface provided with the LED chip in the organic dye layer.

In one embodiment of the present specification, by providing the color filter, it is possible to improve the purity and to block unnecessary light. For example, when green light is required, if the light passing through the organic dye layer includes green and blue light, the green filter may be included only by passing through the color filter.

In one embodiment of the present specification, the color filter may be made of a colorant pigment, a binder resin, and an additive.

In one embodiment of the present specification, the colorant pigment is not limited as long as it is a material used in the art, specifically, may be at least one of phthalocyanine-based, quinophthalone-based, diketopyrrolopyrrole-based.

4 illustrates a lamination structure of a micro LED according to an exemplary embodiment of the present specification. Specifically, FIG. 4 illustrates a structure in which the organic dye layer 20 is provided on the micro LED chip 10 and the color filter 40 is provided on the organic dye layer 20. The micro LED according to the present specification is not limited to the laminated structure of FIG. 4, and further members may be further included.

5 illustrates a lamination structure of a micro LED according to an exemplary embodiment of the present specification. Specifically, FIG. 5 illustrates a diffusion layer 30 on the micro LED chip 10, an organic dye layer 20 on the diffusion layer 30, and a color filter 40 on the organic dye layer 20. It illustrates the structure provided. The micro LED according to the present specification is not limited to the laminated structure of FIG. 5, and further members may be further included.

An exemplary embodiment of the present specification provides a display device including the micro LED described above. Specifically, the display device includes a display module and the aforementioned micro LED. However, the configuration of the display device is not limited thereto, and the structure and configuration are not particularly limited as long as the display device includes the micro LED as a component.

The display device may be a liquid crystal display television, a monitor, a tablet PC or a mobile device. The display device may be manufactured according to a configuration and a method known in the art.

Hereinafter, the present invention will be described in detail with reference to Examples. However, embodiments according to the present disclosure may be modified in various other forms, and the scope of the present disclosure is not interpreted to be limited to the embodiments described below. The embodiments of the present specification are provided to more fully describe the present specification to those skilled in the art.

Example 1.

Polymethyl methacrylate (PMMA) on a blue micro LED chip (LG Innotek, 50μmX30μm), 0.5wt% bodyweight green organic dye based on the weight of polymethylmethacrylate, 5wt% titanium dioxide (TiO ₂ ) And a bar-coated solution containing butyl acetate to form an organic dye layer for realizing a green light of 5μm thickness.

Comparative Example 1.

The inorganic dye layer was formed on the blue micro LED chip (LG Innotek, 50μmX30μm) by coating a solution containing 70wt% of YAG with respect to the weight of the silicone resin to 25μm thickness.

Figure 6 shows the light emission intensity according to the wavelength of the micro LED manufactured in Example 1 and Comparative Example 1. In the case of Example 1, although the coating thickness was formed with a smaller amount of dye than in Comparative Example 1, it can be seen that the brightness is high, the color purity is improved.

Example 2.

Polymethyl methacrylate (PMMA) on green micro LED chip (LG Innotek, 50μmX30μm), 0.2 wt% of bodyweight orange organic dye based on the weight of polymethyl methacrylate, 0.1wt% bodiphy red organic dye, Barco coating a solution containing 5wt% of titanium dioxide (TiO ₂ ) and butyl acetate to form an organic dye layer 5μm thick to implement a red light.

Example 3.

Polymethyl methacrylate (PMMA) on a green micro LED chip (LG Innotek, 50μmX30μm), 0.1wt% of bodiphy red organic dyes by weight of polymethylmethacrylate, 5wt% of titanium dioxide (TiO ₂ ) And a bar-coated solution containing butyl acetate to form an organic dye layer to implement a red light to a thickness of 5μm.

Figure 7 shows the light emission intensity according to the wavelength of the micro LED manufactured in Example 2 and Example 3. From Fig. 7, it can be seen that Example 2 further includes an orange organic dye, which effectively absorbs micro LED light and emits red dye more efficiently than Example 3.

Example 4.

Polymethyl methacrylate (PMMA), 1.6 wt% body weight green organic dye based on the weight of polymethyl methacrylate, 5 wt% titanium dioxide (TiO ₂ ) and butyl acetate on a blue micro LED chip (LG Innotek, 50μmX30μm) Bar coating a solution comprising an organic dye layer for realizing green light was formed to a thickness of 5μm.

Comparative Example 2.

A solution containing polymethyl methacrylate (PMMA), 1.6 wt% dye by weight of polymethyl methacrylate, 5 wt% titanium dioxide (TiO ₂ ) and butyl acetate on a blue micro LED chip (LG Innotek, 50 μm × 30 μm) Bar coating to form a dye layer 5μm thickness to implement a green light. At this time, the dye was used by mixing the body green organic dye and YAG in a 8: 2 mass ratio.

Comparative Example 3.

In Comparative Example 2, a micro LED was manufactured in the same manner as in Comparative Example 2, except that the organic dye and YAG were mixed at a 6: 4 mass ratio.

 Comparative Example 4.

In Comparative Example 2, a micro LED was manufactured in the same manner as in Comparative Example 2, except that the organic dye and YAG were mixed at a 4: 6 mass ratio.

Comparative Example 5.

In Comparative Example 2, a micro LED was manufactured in the same manner as in Comparative Example 2, except that the organic dye and YAG were mixed at a weight ratio of 2: 8.

Comparative Example 6.

Solution containing polymethyl methacrylate (PMMA), 1.6 wt% YAG, 5 wt% titanium dioxide (TiO ₂ ) and butyl acetate on a blue micro LED chip (LG Innotek, 50 μm × 30 μm) Bar coating to form an organic dye layer 5μm thickness to implement a green light.

8 shows the light emission intensity according to the wavelength of the micro LEDs prepared in Example 4 and Comparative Examples 2 to 6. It can be seen that the emission intensity of the green light increased compared with the case where only the organic dye was included (Example 2), when the organic dye was mixed and used (Comparative Examples 2 to 5) and when only the inorganic dye was used (Comparative Example 6). In addition, it can be seen that as the content of the organic dye decreases and the content of the inorganic dye increases (from Comparative Example 2 to 6), the intensity of the green light decreases and the intensity of the blue light increases. That is, as the content of the inorganic dye increases, it can be confirmed that the blue light emitted from the micro LED is not effectively absorbed and thus exhibits the above-described light emission intensity difference.

Example 5.

Polymethyl methacrylate (PMMA), 1.6 wt% body weight green organic dye based on the weight of polymethyl methacrylate, 5 wt% titanium dioxide (TiO ₂ ) and butyl acetate on a blue micro LED chip (LG Innotek, 50μmX30μm) Bar coating a solution comprising an organic dye layer for realizing green light was formed to a thickness of 5μm.

Comparative Example 7.

On the blue micro LED chip (LG Innotek, 50μmX30μm), polymethyl methacrylate (PMMA), 1.6wt% of bodiphy based green organic dyes by weight of polymethylmethacrylate, 50wt% of YAG, 5wt% of dioxide A dye layer for realizing green light was formed by bar coating a solution including titanium (TiO ₂ ) and butyl acetate to a thickness of 5 μm.

Comparative Example 8.

In Comparative Example 7, a micro LED was manufactured in the same manner as in Comparative Example 7, except that 30 wt% of YAG was used.

Comparative Example 9.

Organic to realize green light by bar coating a solution containing polymethyl methacrylate (PMMA), 70wt% of YAG and butyl acetate based on the weight of polymethyl methacrylate on a blue micro LED chip (LG Innotek, 50μmX30μm) The dye layer was formed to a thickness of 5 μm.

9 shows the light emission intensity according to the wavelength of the prepared micro LED prepared in Example 5 and Comparative Examples 7 to 9. From Figure 9, it can be confirmed that the implementation of the green light should be included organic dyes. In addition, when the content of the organic dye is the same, it can be seen that the content of YAG does not affect the emission intensity.

Claims (11)

Micro LED chip; And An organic dye layer formed on the micro LED chip, The organic dye layer is a micro LED comprising one or more organic dyes. The method according to claim 1, Micro LED is provided with a diffusion layer between the micro LED chip and the organic dye layer. The method according to claim 2, The diffusion layer is a micro LED comprising an inorganic particle and a binder resin. The method according to claim 3, The diffusion layer further comprises at least one of an organic dye and an inorganic phosphor. The method according to claim 2, The thickness of the diffusion layer is from 100nm to 10μm micro LED. The method according to claim 1, The organic dye is one of bodiphy based, perylene based, acridine based, xanthene based, aryl methane based, coumarin based, pyrrole based, rhodamine based, pyryl based, phenoxazone based, stilbene based, terphenyl based and quarter phenyl based Micro LED which includes the above. The method according to claim 1, The organic dye is a micro LED comprising two or more organic dyes. The method according to claim 1, The organic dye layer is a micro LED comprising two or more regions of different maximum emission wavelength. The method according to claim 1, Micro LED further comprises a color filter on the organic dye layer. The method according to claim 1, The organic dye layer has a thickness of 1 μm to 20 μm. Display device comprising the micro LED according to any one of claims 1 to 10.

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