Micro-LED-based display device and manufacturing method thereof

Abstract

Embodiments of a display device are described. A display device includes a substrate (204) and a sub-pixel (R1, R2) configured to emit display light having an emission spectrum having a first peak wavelength and a second peak wavelength. The sub-pixel includes a micro LED (218) disposed on the substrate and an NS-based CC layer (220) disposed on the micro LED. The NS-based CC layer includes a QD configured to emit first light having a first peak wavelength. The micro LED is configured to emit second light having a second peak wavelength. A first portion of the second light is absorbed by the QD and down-converted into the first light and a second portion of the second light is transmitted through the NS-based CC layer (220).

Description

Technical Field

[0001] The present invention relates to a display device having sub-pixels with micro-sized light emitting diodes ("micro-LEDs") and a color conversion (CC) layer. Background Art

[0002] Light-emitting nanostructures (NS), such as quantum dots (QDs), represent a class of phosphors that have the ability to emit light at a single spectral peak with a narrow line width, thereby producing highly saturated colors. The emission wavelength can be tuned based on the size of the NS. The NS is used to produce a NS film, which can be used as a color conversion (CC) layer (also known as a color down-conversion layer) in a display device. The NS-based CC layer can down-convert (down-convert) light from a shorter wavelength region of the visible spectrum to light in a longer wavelength region of the visible spectrum.

[0003] The display device may be based on micro-LED technology and may have red, green, and blue emitting micro-LEDs as light sources in its red, green, and blue sub-pixels. These micro-LED-based display devices have a tradeoff between achieving the required high color brightness (e.g., brightness equal to or greater than about 50,000 nits) and the required primary emission peak wavelength corresponding to the desired color point and / or color gamut for light emitted from the red, green, and / or blue sub-pixels on the RGB color space (e.g., the 1931 CIE color space). For example, a GaN-based micro-LED used in a red sub-pixel emits red light in the wavelength region of about 620 nm to about 630 nm, but has a low color brightness equal to or less than about 5,000 nits and a current equal to or less than about 2 A / cm 2 GaN-based micro-LEDs cannot achieve the desired high color brightness of about 50,000 nits or more and current density of about 4A / cm 2 In contrast, GaN-based micro LEDs emit light in a wavelength region of about 580 nm to about 600 nm, which corresponds to orange light and an orange point on the 1931 CIE color space, thus reducing the image quality of the display device.

[0004] One of the parameters used to define the light emitted from a display device is Figure 1The chromaticity (x, y) coordinates of the 1931 CIE chromaticity diagram shown in . The 1931 CIE chromaticity diagram (also called the "1931 CIE color space") is a graphical representation of all colors perceived by the human eye. The horseshoe-shaped spectrum locus 100 is a set of points representing the chromaticity (x, y) coordinates of spectral (monochromatic) colors, plotted against their wavelength. The chromaticity (x, y) coordinates of any naturally occurring color lie within the boundaries of the spectrum locus 100.

[0005] The color gamut boundaries of various display device technologies or specifications can be plotted within the 1931 CIE Chromaticity Diagram by connecting the chromaticity (x,y) coordinates of the display device's three display color primaries. The color gamut defines the limits of the colors that can be produced or defined for a display device technology or specification. Figure 1 The color gamut of the DCI specification is illustrated as a triangle 102 with vertices for each of the primary display colors of red, green, and blue (RGB). The chromaticity (x, y) coordinates of the vertices of triangle 102 are (0.680, 0.320), (0.265, 0.690), and (0.150, 0.060) for red, green, and blue, respectively. Summary of the invention

[0006] The present disclosure provides an exemplary micro-LED-based display device that minimizes or eliminates the existing tradeoff between achieving a desired color brightness of a micro-LED-based display device and a desired color point and / or color gamut of light emitted from a red subpixel. The present disclosure also provides an exemplary cost-effective method for manufacturing such an improved device.

[0007] In some embodiments, a micro-LED-based display device may include red, green, and blue sub-pixels. Each of the red, green, and blue sub-pixels may include a micro-LED. In some embodiments, the blue sub-pixel may include a micro-LED that emits blue light having a primary emission peak wavelength (PWL) in a wavelength range of about 435 nm to about 495 nm of the EM spectrum. In some embodiments, the green sub-pixel may include a micro-LED that emits green light having a primary emission PWL in a wavelength range of about 495 nm to about 570 nm of the EM spectrum. In some embodiments, the red sub-pixel may include a micro-LED that emits green light having a primary emission PWL in a wavelength range of about 4A / cm 2In some embodiments, the red sub-pixel may further include a nanostructure-based (NS-based) color conversion (CC) layer disposed on the red sub-pixel micro-LED. The NS-based CC layer may include a light-emitting nanostructure having a primary emission PWL in a wavelength range of about 620 nm to about 750 nm (which may correspond to red light).

[0008] In some embodiments, a first portion of the light from the red sub-pixel micro-LED may be absorbed by the light-emitting nanostructures of the NS-based CC layer and re-emitted as light with a primary emission PWL of the light-emitting nanostructures. In some embodiments, a second portion of the light from the red sub-pixel micro-LED may be allowed to transmit through the NS-based CC layer. In some embodiments, the NS-based CC layer may be formed to have an optical density of about 0.1 to about 3.0 to allow about 70% to about 1% of the micro-LED light to be transmitted through the NS-based CC layer at the primary emission PWL, respectively. As a result, the light transmitted from the red sub-pixel may have a dual PWL emission spectrum.

[0009] In some embodiments, the dual PWL emission spectrum may include a first emission PWL corresponding to a primary emission PWL of the light-emitting nanostructure (e.g., about 620 nm to about 750 nm) and a second emission PWL corresponding to a primary emission PWL of the transmitted micro-LED light (e.g., about 550 nm to about 610 nm). In some embodiments, the dual PWL emission spectrum may correspond to Figure 1 In some embodiments, the mixed color point may have a chromaticity (x, y) coordinate along a line between a chromaticity (x, y) coordinate of about (0.5, 0.5) and a chromaticity (x, y) coordinate of about (0.7, 0.3) on the 1931 CIE chromaticity diagram. In some embodiments, the dual PWL emission spectrum may include a first emission PWL at about 640 nm and a second emission PWL at about 595 nm. The dual PWL emission spectrum may correspond to a mixed color point having a chromaticity (x, y) coordinate of about (0.680, 0.320), which is a red point on the 1931 CIE color space perceived by the human eye.

[0010] Thus, by using a NS-based CC layer having a red-emitting (red-light-emitting) light-emitting nanostructure on an orange-emitting microLED having an external quantum efficiency greater than about 2% in the red sub-pixel, red light emission with high red brightness (e.g., a brightness greater than about 25,000 nits, or a brightness greater than about 50,000 nits) can be achieved from the red sub-pixel of a micro-LED-based display device.

[0011] According to some embodiments, a display device includes a substrate and a sub-pixel configured to emit display light having an emission spectrum having a first peak wavelength and a second peak wavelength. The sub-pixel includes a micro-LED disposed on the substrate and a NS-based CC layer disposed on the micro-LED. The NS-based CC layer includes a QD configured to emit a first light having a first peak wavelength. The micro-LED is configured to emit a second light having a second peak wavelength. A first portion of the second light is absorbed by the QD and down-converted into the first light, and a second portion of the second light is transmitted through the NS-based CC layer.

[0012] According to some embodiments, the first peak wavelength is within a wavelength range of about 620 nm to about 750 nm.

[0013] According to some embodiments, the second peak wavelength is within a wavelength range of about 550 nm to about 610 nm.

[0014] According to some embodiments, the first peak wavelength and the second peak wavelength are in different and adjacent wavelength regions of the electromagnetic (EM) spectrum.

[0015] According to some embodiments, the first peak wavelength is in the red wavelength region of the electromagnetic (EM) spectrum and the second peak wavelength is in the orange or yellow wavelength region of the EM spectrum.

[0016] According to some embodiments, the intensity of the first peak wavelength is greater than the intensity of the second peak wavelength.

[0017] According to some embodiments, a peak intensity ratio of the first peak wavelength to the second peak wavelength ranging from about 0 to about 40 corresponds to an optical transmittance of the micro-LED at the second peak wavelength ranging from about 100% to about 1%.

[0018] According to some embodiments, the emission spectrum corresponds to a single color point having first chromaticity (x, y) coordinates on an RGB color space.

[0019] According to some embodiments, a peak intensity ratio of the first peak wavelength to the second peak wavelength ranging from about 0 to about 40 corresponds to first chromaticity (x, y) coordinates ranging from about (0.6, 0.4) to about (0.7, 0.3), respectively.

[0020] According to some embodiments, the optical density of the NS-based CC layer ranging from about 0 to about 3.0 corresponds to first chromaticity (x, y) coordinates ranging from about (0.6, 0.4) to about (0.7, 0.3), respectively.

[0021] According to some embodiments, a light transmission of the micro-LED ranging from about 100% to about 1% at the second peak wavelength corresponds to an optical density of the NS-based CC layer ranging from about 0 to about 3.0.

[0022] According to some embodiments, the emission spectrum corresponds to a single color point having a first chromaticity (x, y) coordinate along a coordinate line between a second chromaticity (x, y) coordinate of approximately (0.5, 0.5) and a third chromaticity (x, y) coordinate of approximately (0.7, 0.3) of the RGB color space.

[0023] According to some embodiments, the micro LED has a light transmittance of about 1% to about 70% through the NS-based CC layer at the second peak wavelength.

[0024] According to some embodiments, the NS-based CC layer comprises a surface area of ​​about 0.5 μm x about 0.5 μm to about 1000 μm x about 1000 μm.

[0025] According to some embodiments, the NS-based CC layer covers the entire top surface area (region) of the micro-LED.

[0026] According to some embodiments, the top surface area of ​​the NS-based CC layer is larger than the top surface area of ​​the micro-LED.

[0027] According to some embodiments, the NS-based CC layer comprises a thickness of about 5 μm to about 40 μm.

[0028] According to some embodiments, the NS-based CC layer comprises an optical density of about 0.1 to about 3.0.

[0029] According to some embodiments, the display device further includes a second sub-pixel, the second sub-pixel including a second micro-LED disposed on the substrate, the second micro-LED being configured to emit a second display light having an emission spectrum including a single peak wavelength within a wavelength range of about 495 nm to about 570 nm of an electromagnetic (EM) spectrum.

[0030] According to some embodiments, the display device further includes a second sub-pixel, the second sub-pixel including a second micro-LED disposed on the substrate, the second micro-LED being configured to emit a second display light having an emission spectrum including a single peak wavelength within a wavelength range of about 435 nm to about 495 nm of an electromagnetic (EM) spectrum.

[0031] According to some embodiments, a display device includes a substrate, a first subpixel, and a second subpixel, wherein the first subpixel is configured to emit a first display light having a first emission spectrum including a first peak wavelength and a second peak wavelength, and the second subpixel is configured to emit a second display light having a second emission spectrum including a third peak wavelength and a fourth peak wavelength. The first subpixel includes a first microLED disposed on the substrate and a first nanostructure-based color conversion (NS-based CC) layer disposed on the first microLED. The first NS-based CC layer includes a first group of quantum dots (QDs) configured to emit a first light having a first peak wavelength. The first microLED is configured to emit a second light having a second peak wavelength. The second subpixel includes a second microLED disposed on the substrate and a second NS-based CC layer disposed on the second microLED. The second NS-based CC layer includes a second group of quantum dots (QDs) configured to emit a third light having a third peak wavelength. The second microLED is configured to emit a fourth light having a fourth peak wavelength.

[0032] According to some embodiments, the first emission spectrum corresponds to a first color point having a first chromaticity (x, y) coordinate on the RGB color space, and the second emission spectrum corresponds to a second color point having a second chromaticity (x, y) coordinate on the RGB color space. The second chromaticity (x, y) coordinate is different from the first chromaticity (x, y) coordinate.

[0033] According to some embodiments, the first peak wavelength and the third peak wavelength are within a wavelength range of about 620 nm to about 750 nm.

[0034] According to some embodiments, the second peak wavelength and the fourth peak wavelength are within a wavelength range of about 550 nm to about 610 nm.

[0035] According to some embodiments, the optical density of the first NS-based CC layer is different from the optical density of the second NS-based CC layer.

[0036] According to some embodiments, the thickness of the first NS-based CC layer is different from the thickness of the second NS-based CC layer.

[0037] According to some embodiments, the concentration of the first set of QDs is different from the concentration of the second set of QDs.

[0038] According to some embodiments, a first portion of the second light is absorbed by the first group of QDs and down-converted into the first light, and a second portion of the second light is transmitted through the first NS-based CC layer.

[0039] According to some embodiments, a first portion of the fourth light is absorbed by the second group of QDs and down-converted into third light, and a second portion of the fourth light is transmitted through the second NS-based CC layer.

[0040] According to some embodiments, the first microLED has a first optical transmittance of about 1% to about 70% through the first NS-based CC layer at a second peak wavelength, and the second microLED has a second optical transmittance of about 1% to about 70% through the second NS-based CC layer at a fourth peak wavelength. The second optical transmittance is different from the first optical transmittance.

[0041] According to some embodiments, a method of manufacturing a display device includes forming a first microLED and a second microLED on a substrate, depositing a quantum dot (QD) layer on the first microLED and the second microLED, masking a first portion of the QD layer, performing a hardening process on the second portion of the QD layer, and removing the first portion of the QD layer. The first microLED is formed to emit a first display light having a first emission spectrum with a double peak wavelength, and the second microLED is formed to emit a second display light having a second emission spectrum with a single peak wavelength.

[0042] According to some embodiments, depositing the layer of QDs includes spin coating, slot die coating, doctor blade coating, or rod coating a solution of QDs on the first and second microLEDs.

[0043] According to some embodiments, masking the first portion of the layer of QDs includes selectively forming a photoresist layer on the first portion of the layer of QDs on the second micro LED.

[0044] According to some embodiments, performing a hardening process on the second portion of the QD layer includes curing the second portion of the QD layer on the first micro LED with ultraviolet radiation.

[0045] According to some embodiments, removing the first portion of the QD layer includes washing the first portion of the QD layer in an alkaline solution.

[0046] According to some embodiments, a method of manufacturing a display device includes forming a first microLED and a second microLED on a substrate, forming a patterned template on the first microLED and the second microLED, depositing a quantum dot (QD) layer on the patterned template, masking a first portion of the QD layer, performing a hardening process on a second portion of the QD layer, and removing the first portion of the QD layer. The first microLED is formed to emit a first display light having a first emission spectrum with a double peak wavelength, and the second microLED is formed to emit a second display light having a second emission spectrum with a single peak wavelength. The patterned template includes an opening on the first microLED.

[0047] According to some embodiments, forming the patterned template includes depositing a polymer layer on the first microLED and the second microLED and patterning the polymer layer to form an opening on the first microLED.

[0048] According to some embodiments, depositing the QD layer includes spin coating, slot die coating, doctor blade coating, or rod coating a solution of QDs on the patterned template.

[0049] According to some embodiments, performing a hardening process on the second portion of the QDs layer includes curing the second portion of the QD layer disposed in the opening using ultraviolet radiation.

[0050] According to some embodiments, removing the first portion of the QD layer includes washing the first portion of the QD layer in toluene.

[0051] Other features and advantages of the present invention and the structure and operation of various embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited to the specific embodiments described herein. These embodiments are presented herein for illustrative purposes only. Based on the teachings included herein, other embodiments will become clear to those skilled in the relevant art. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments of the invention and, together with the description, further serve to explain the principles of embodiments of the invention and to enable those skilled in the relevant art to make and use the embodiments of the invention.

[0053] Figure 1 is a 1931 CIE chromaticity diagram showing the color gamut of the Digital Cinema Initiatives (DCI) color space.

[0054] Figure 2A A top view of a display device having micro-LED based sub-pixels according to some embodiments is shown.

[0055] Figure 2B-2F Different cross-sectional views of a display device having micro-LED based sub-pixels according to some embodiments are shown.

[0056] Figures 3A to 4B 5 and 5 show optical characteristics of a display device having micro-LED based sub-pixels according to some embodiments.

[0057] Figure 6 is a flow chart of a method for manufacturing a display device having micro-LED based sub-pixels according to some embodiments.

[0058] Figure 7-10 Cross-sectional views of a display device having micro-LED based sub-pixels at various stages are shown, according to some embodiments.

[0059] Fig.11 is a flow chart of another method for manufacturing a display device having micro-LED based sub-pixels according to some embodiments.

[0060] Figure 12-17 Cross-sectional views of a display device having micro-LED based sub-pixels at various stages are shown, according to some embodiments.

[0061] Fig.18 A cross-sectional view of a nanostructure according to some embodiments is shown.

[0062] Fig.19 A top view of a nanostructure film according to some embodiments is shown.

[0063] When combined with the accompanying drawings, the features and advantages of the present invention will become more clear from the detailed description set forth below, wherein the same reference numerals always identify corresponding elements. In the accompanying drawings, the same reference numerals generally indicate the same, functionally similar and / or structurally similar elements. Unless otherwise stated, the discussion of elements with the same annotations applies to each other. Unless otherwise stated, the drawings provided throughout this disclosure should not be interpreted as drawings drawn to scale. DETAILED DESCRIPTION

[0064] Although specific configurations and arrangements may be discussed, it should be understood that this is done for illustrative purposes only. Those skilled in the relevant art will recognize that other configurations and arrangements may be used without departing from the spirit and scope of the present invention. It is clear to those skilled in the relevant art that the present invention may also be used in various other applications except those specifically mentioned herein. It should be understood that the specific embodiments shown and described herein are examples and are not intended to limit the scope of the application in any way.

[0065] It should be noted that references in the specification to "one (single) embodiment", "embodiment", "example embodiment", etc. indicate that the described embodiment may include a particular feature, structure or characteristic, but each (single) embodiment may not necessarily include the particular feature, structure or characteristic. In addition, such phrases do not necessarily refer to the same embodiment. In addition, when a particular feature, structure or characteristic is described in conjunction with an embodiment, whether or not explicitly described, it will be within the knowledge of those skilled in the art to implement such feature, structure or characteristic in conjunction with other embodiments.

[0066] Unless expressly indicated otherwise, all numbers in this description expressing amounts of material, ratios, physical properties of material and / or use are to be understood as modified by the word "about".

[0067] In some embodiments, the terms "about" and "substantially" can indicate that a value of a given amount varies within 5% of that value (e.g., 1%, 2%, 3%, 4%, 5%). These values ​​are examples only and are not intended to be limiting. The terms "about" and "substantially" may refer to a percentage of a value as interpreted by one skilled in the relevant art based on the teachings herein.

[0068] In some embodiments, the term "display device" refers to an arrangement of elements that allow data to be visually represented on a display screen. Suitable display screens may include various flat, curved or other shaped screens, films, sheets or other structures for visually displaying information to a user. The display device described herein may be included in, for example, a display system including a liquid crystal display (LCD), a television, a computer, a mobile phone, a smart phone, a personal digital assistant (PDA), a gaming device, an electronic reading device, a digital camera, a tablet computer, a wearable device, a car navigation system, etc.

[0069] In some embodiments, term " nanostructure " refers to the structure with at least one region or characteristic dimension less than about 500nm of size.In some embodiments, nanostructure has the size less than about 200nm, less than about 100nm, less than about 50nm, less than about 20nm or less than about 10nm.Usually, region or characteristic dimension will be along the minimum axis of structure.The example of this structure comprises nanowire, nanorod, nanotube, branched nanostructure, nano tetrapod, tripod, dipod, nanocrystal, nano dot, QD, nanoparticle etc.Nanostructure can be for example substantially crystalline, substantially monocrystalline, polycrystalline, amorphous or its combination.In some embodiments, each in the three dimensions of nanostructure has the size less than about 500nm, less than about 200nm, less than about 100nm, less than about 50nm, less than about 20nm or less than about 10nm.

[0070] In some embodiments, the term "QD" or "nanocrystal" refers to a substantially monocrystalline nanostructure. The nanocrystal has at least one region or characteristic dimension less than about 500nm in size, and is as low as the order of magnitude less than about 1nm. The terms "nanocrystal", "QD", "nano-dot" and "point" are easily understood by those of ordinary skill to represent similar structures and are used interchangeably in this article. The present invention also includes the use of polycrystalline or amorphous nanocrystals.

[0071] In some embodiments, the "diameter" of the term nanostructure refers to the diameter of the cross section perpendicular to the first axis of the nanostructure, wherein the first axis has the maximum length difference relative to the second axis and the third axis (the second axis and the third axis are two axes that are closest to each other in length). The first axis is not necessarily the longest axis of the nanostructure; for example, for a disc-shaped nanostructure, the cross section will be a substantially circular cross section perpendicular to the short longitudinal axis of the disc. In the case where the cross section is not circular, the diameter is the average value of the major axis and the minor axis of the cross section. For elongated or high aspect ratio nanostructures, such as nanowires, the diameter is measured on a cross section perpendicular to the longest axis of the nanowire. For spherical nanostructures, the diameter is measured from one side to the other through the center of the sphere.

[0072] In some embodiments, when used for nanostructure, the term "crystalline" or "substantially crystalline" refers to the fact that nanostructure shows long-range order on one or more dimensions of structure usually. It will be appreciated by those skilled in the art that the term "long-range order" will depend on the absolute size of a specific nanostructure, because the orderedness of a single crystal cannot extend beyond the boundary of the crystal. In this case, "long-range order" will mean that the substance on at least most of the size of a nanostructure is ordered. In some cases, a nanostructure can be with an oxide or other coating, or can be made up of a core and at least one shell. In this case, it should be understood that an oxide, shell or other coating can but need not show this orderliness (for example, it can be amorphous, polycrystalline or other). In this case, phrases "crystalline", "substantially crystalline", "substantially monocrystalline" or "monocrystalline" refer to the central core (not including coating or shell) of a nanostructure. As used herein, term " crystalline " or " substantially crystalline " are intended to also contain the structure that comprises various defects, stacking faults (stacking faults), atomic substitution etc., as long as this structure shows significant long-range order (for example, at least about 80% of the length of at least one axis of nanostructure or its core is ordered).In addition, it should be understood that the interface between core and nanostructure outside or between core and adjacent shell or between shell and second adjacent shell can comprise non-crystalline region, and can even be amorphous.This can not stop nanostructure to be crystalline as defined herein or substantially crystalline.

[0073] In some embodiments, the term "single crystalline" when used for a nanostructure means that the nanostructure is substantially crystalline and consists essentially of a single crystal. When used for a nanostructure heterostructure comprising a core and one or more shells, "single crystalline" means that the core is substantially crystalline and consists essentially of a single crystal.

[0074] In some embodiments, the term "ligand" refers to a molecule capable of interacting (whether weakly or strongly) with one or more faces of a nanostructure, such as by covalent, ionic, van der Waals or other molecular interactions with the surface of the nanostructure.

[0075] In some embodiments, the term "quantum yield" (QY) refers to, for example, the ratio of photons emitted by a nanostructure or a population of nanostructures to photons absorbed. As known in the art, quantum yield is typically determined by comparison methods using well-characterized standard samples with known quantum yield values.

[0076] In some embodiments, the term "primary emission peak wavelength" refers to the wavelength at which the emission spectrum exhibits the highest intensity.

[0077] In some embodiments, the term "full width at half maximum" (FWHM) refers to a measure of the width of a spectrum. In the case of an emission spectrum, FWHM may refer to the width of the emission spectrum at half the peak intensity value.

[0078] In some embodiments, the terms "luminance" and "brightness" are used interchangeably herein and refer to a photometric measurement of the luminous intensity per unit area of ​​a light source or illuminated surface.

[0079] In some embodiments, the term "nanostructure (NS) film" refers to a film having light-emitting nanostructures.

[0080] In some embodiments, the term "red sub-pixel" refers to a region of a pixel and / or display device that emits light. The light may have a primary emission peak wavelength within a wavelength range of about 550 nm to about 750 nm of the electromagnetic (EM) spectrum. Additionally or alternatively, the device may emit light having a chromaticity (x, y) coordinate along a line between a chromaticity (x, y) coordinate of about (0.5, 0.5) and a chromaticity (x, y) coordinate of about (0.7, 0.3) of the 1931 CIE Chromaticity Diagram.

[0081] In some embodiments, the term "green sub-pixel" refers to a region of a pixel and / or display device that emits light having a primary emission peak wavelength within a wavelength range of about 495 nm to about 570 nm of the EM spectrum.

[0082] In some embodiments, the term "blue sub-pixel" refers to a region of a pixel and / or display device that emits light having a primary emission peak wavelength within a wavelength range of about 435 nm to about 495 nm of the EM spectrum.

[0083] The disclosed patents, patent applications, websites, company names and scientific literature mentioned herein are incorporated herein by reference in their entirety, to the same extent as each is specifically and individually indicated to be incorporated herein by reference. Any conflict between any reference cited herein and the specific teachings of this specification sheet should be resolved in a manner that is favorable to the latter. Similarly, any conflict between the definition of a word or phrase understood in the art and the definition of a word or phrase specifically taught in this specification sheet should be resolved in a manner that is favorable to the latter.

[0084] Unless defined otherwise, technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which this application belongs. Reference is made herein to various methodologies and materials known to one of ordinary skill in the art.

[0085] Example Embodiments of Display Devices

[0086] Figure 2A A top view of a micro-LED based display device 200 is shown according to some embodiments. Figure 2B and 2D -2F shows the micro-LED based display device 200 along Figure 2A Different cross-sectional views of line AA. Figure 2C The micro LED-based display device 200 is shown along Figure 2A A cross-sectional view of line BB. Figure 2B-2F A cross-sectional view of a micro-LED based display device 200 is shown with the LEDs not shown for simplicity. Figure 2A Unless otherwise noted, discussions of elements with the same annotations apply to each other.

[0087] refer to Figure 2A In some embodiments, the micro LED-based display device 200 may include red sub-pixels R1 - R8 , green sub-pixels G1 - G4 , and blue sub-pixels B1 - B4 disposed on a substrate 204 . Figure 2A The number and arrangement of red, green, and blue sub-pixels in the micro-LED-based display device 200 shown in FIG. 2 are exemplary and not limiting. The micro-LED-based display device 200 may have any number and any arrangement of red, green, and blue sub-pixels. Unless otherwise noted, the discussion of (i) red sub-pixel R1 applies to red sub-pixels R2-R8, (ii) green sub-pixel G1 applies to green sub-pixels G2-G4, and (iii) blue sub-pixel Bl applies to blue sub-pixels B2-B4.

[0088] In some embodiments, the micro-LED-based display device 200 may further include a dielectric layer 206 disposed between the red sub-pixels R1-R8, the green sub-pixels G1-G4, and the blue sub-pixels B1-B4 and on the substrate 204, such as Figure 2B-2F The dielectric layer 206 can electrically and / or optically isolate the red sub-pixels R1-R8, the green sub-pixels G1-G4, and the blue sub-pixels B1-B4 from each other. In some embodiments, the micro-LED-based display device 200 can additionally or optionally include a light blocking layer 208 (also referred to as a "black matrix layer 208") disposed on the dielectric layer 206, such as Figure 2D As shown in . The light blocking layer 208 can prevent or minimize optical crosstalk between the red sub-pixels RL-R8, the green sub-pixels G1-G4, and the blue sub-pixels BL-B4. In some embodiments, the micro-LED-based display device 200 can additionally or optionally include an encapsulation layer 210, such as Figure 2E In some embodiments, the encapsulation layer 210 may be disposed on Figure 2D and 2F The encapsulation layer 210 may include an insulating oxide layer, such as aluminum oxide, to provide an environmental seal to underlying layers and / or structures of the micro LED based display device 200 .

[0089] refer to Figure 2A-2B 2D-2F, in some embodiments, each of the green sub-pixels G1-G4 may include a micro LED 212 that may emit green light having a primary emission PWL of about 495 nm to about 570 nm in the visible spectrum. Figure 2A and 2C In some embodiments, each of the blue sub-pixels BL-B4 may include a micro-LED 214 that may emit blue light having a primary emission PWL of about 435 nm to about 495 nm in the visible spectrum. In some embodiments, the green sub-pixels G1-G4 and / or the blue sub-pixels B1-B4 may include a color filter 216, such as Figure 2F . The color filter (color filter) 216 can tune the spectral emission width of the light emitted from the micro LEDs 212 and / or 214 to achieve the desired color gamut on the 1931 CIE color space. In some embodiments, instead of the color filter 216, the green sub-pixels G1-G4 and / or the blue sub-pixels BL-B4 may include an optically transparent substrate.

[0090] refer to Figure 2A-2BIn some embodiments, each of the red sub-pixels R1-R8 may include a micro-LED 218 disposed on the substrate 204 and a NS-based CC layer 220 disposed on the micro-LED 218. The micro-LED 218 may be an indium gallium nitride (InGaN) micro-LED configured to provide a current of about 4 A / cm2 or higher. 2 The MOSFET emits light having a primary emission PWL of about 550 nm to about 610 nm, a FWHM of about 20 nm to about 30 nm, and a high color brightness of about 25,000 nits to about 50,000 nits or greater at a high current density of about 100 nm. The light having a primary emission PWL of about 550 nm to about 610 nm may correspond to yellow, orange, or amber light of the visible spectrum.

[0091] In some embodiments, the NS-based CC layer 220 may include a substrate disposed on a matrix material (eg, Fig.19 The light-emitting nanostructures in the matrix material 1910, such as QDs (e.g., reference Fig.18 The QD 1800 described herein). According to some embodiments, the light-emitting nanostructure may have a primary emission PWL of about 620 nm to about 750 nm and a FWHM of about 10 nm to about 40 nm, which may correspond to red light. In some embodiments, the light-emitting nanostructure may include an indium phosphide (InP) or cadmium selenide (CdSe) based QD having a QY of about 65% to about 80%. In some embodiments, the red sub-pixels R1-R8 may further include other optically transparent insulating or conductive layers (not shown) between the NS-based CC layer 220 and the micro-LED 218.

[0092] In some embodiments, substrate 204 may include circuitry (not shown) for controlling micro-LEDs 212, 214, and 218. Each of micro-LEDs 212, 214, and 218 may have a lateral dimension of less than about 100 μm. The structure of micro-LEDs 212, 214, and 218 may be based on a pn junction diode having a direct bandgap semiconductor material, such as a binary III-V (e.g., GaN) compound, a ternary III-V compound (e.g., InGaN), a quaternary III-V compound (e.g., AlInGaN), or a combination thereof.

[0093] In some embodiments, each NS-based CC layer 220 may have a thickness of about 5 μm to about 40 μm to sufficiently output light having a desired PWL and a desired color point from each of the red sub-pixels R1-R8, as described in detail below. Each NS-based CC layer 220 may have a surface area covering the entire top surface area (area) of each micro-LED 218 to minimize or prevent optical crosstalk between the micro-LEDs 212, 214, and 218. In some embodiments, each NS-based CC layer 220 may have a surface area of ​​about 0.5 μm x about 0.5 μm to about 1000 μm x about 1000 μm (e.g., about 2 μm x 2 μm to about 100 μm x 100 μm).

[0094] In each of the red sub-pixels R1-R8, a first portion of the light from the micro-LED 218 may be absorbed by the light-emitting nanostructures of the NS-based CC layer 220 and re-emitted as light having a primary emission PWL of the light-emitting nanostructures. A second portion of the light from the micro-LED 218 may be allowed to transmit through the NS-based CC layer 220. As a result, the light transmitted from each of the red sub-pixels R1-R8 may have a dual-PWL emission spectrum. In some embodiments, the dual-PWL emission spectrum may include a first emission PWL corresponding to a primary emission PWL of the light-emitting nanostructure (e.g., about 620nm to about 750nm) and a second emission PWL corresponding to a primary emission PWL of the light transmitted from the micro-LED 218 (e.g., about 550nm to about 610nm). The dual-PWL emission spectrum may correspond to Figure 1 ) (also referred to as a "mixed color point") on the 1931 CIE chromaticity diagram shown in FIG. 1 . In some embodiments, the mixed color point may be a red color point. Therefore, by using a NS-based CC layer 220 on the micro-LED 218, light emission having a red color point on the 1931 CIE chromaticity diagram may be achieved from the red sub-pixels R1-R8 without compromising a color brightness of about 25,000 nits to about 50,000 nits or greater than about 50,000 nits. Due to the challenges of producing a micro-LED with red light of such high color brightness, as discussed above, the red sub-pixels may emit orange light for such high color brightness without using a NS-based CC layer 220.

[0095] In some embodiments, the mixed color point may have a chromaticity (x, y) coordinate along a coordinate line between a chromaticity (x, y) coordinate of about (0.5, 0.5) and a chromaticity (x, y) coordinate of about (0.7, 0.3) on the 1931 CIE Chromaticity Diagram. The coordinate line may be Figure 1. Based on the desired color point of the red sub-pixels R1-R8, the mixed color point of the light emitted from the red sub-pixels R1-R8 can be changed along this coordinate line by changing the optical density of the NS-based CC layer 220. Changing the optical density of the NS-based CC layer 220 can change (i) the percentage of light transmitted from the micro LEDs 218 through the NS-based CC layer 220, and (ii) the relative peak intensities of the first and second emission PWLs of the dual PWL emission spectrum.

[0096] The optical density of the NS-based CC layer 220 can be adjusted by adjusting the thickness of the NS-based CC layer 220, the concentration of the luminescent nanostructures in the NS-based CC layer 220, and / or the scattering particles in the NS-based CC layer 220 (hereinafter referred to as Fig.19 In some embodiments, the NS-based CC layer 220 can be formed to have an optical density of about 0.1 to about 3.0, which can allow about 70% to about 0.1% light transmission at the primary emission PWL from the micro LEDs 218 through the NS-based CC layer 220, respectively.

[0097] In some embodiments, the mixed color point can be changed along the coordinate line by changing the first emission PWL and the second emission PWL of the dual PWL emission spectrum. The first and second emission PWLs can be changed by changing the emission properties of the micro-LED 218 and the NS-based CC layer 220. In some embodiments, two or more of the red sub-pixels R1-R8 may have (i) NS-based CC layers 220 with different optical densities from each other, (ii) NS-based CC layers 220 with different concentrations of light-emitting nanostructures from each other, and / or (iii) micro-LEDs 218 that operate at different current densities and emit light with different primary emission PWLs from each other in the wavelength range of about 550 nm to about 610 nm. As a result, two or more of the red sub-pixels R1-R8 may emit light with dual PWL emission spectra and corresponding mixed color points that are different from each other.

[0098] Figure 3A An example dual PWL emission spectrum 322 of one or more of the red sub-pixels R1-R8 is shown, and Figure 3BThe corresponding mixed color point CP1 on a portion of the 1931 CIE chromaticity diagram is shown. In this example, (i) the NS-based CC layer 220 may have an optical density of about 1.0 and a thickness of about 5 μm, (ii) the micro-LED 218 may have a primary emission PWL of about 595 nm and a light transmittance of about 10% at a PWL of about 595 nm, and (iii) the light-emitting nanostructure may have a primary emission PWL of about 640 and a FWHM of about 30 nm. The dual PWL emission spectrum 322 may include a first emission PWL 322A at about 640 nm and a second emission PWL 322B at about 595 nm. The peak intensity ratio of the first emission PWL 322A to the second emission PWL 322B may be about 3.36. The dual PWL emission spectrum 322 having a peak intensity ratio of about 3.36 may correspond to a mixed color point CP1 having chromaticity (x, y) coordinates of about (0.663, 0.336), which is the red point on the 1931 CIE color space perceived by the human eye. Figure 3B As shown in , the color point CP1 corresponding to the dual-PWL emission spectrum 322 is similar to the color point corresponding to the single-PWL emission spectrum having a PWL in the wavelength range of about 615 to about 620 nm.

[0099] Figure 3A-3B Also shown is an example emission spectrum 324 of light emitted from the micro LED 218 without being transmitted through the NS-based CC layer 220 (i.e., 100% light transmittance at the primary emission PWL from the micro LED 218) and a color point CP2 corresponding to the emission spectrum 324. The color point CP2 has chromaticity (x, y) coordinates of approximately (0.601, 0.398), which is an orange color point on the 1931 CIE color space.

[0100] Figure 3A-3B Further shown are an example emission spectrum 326 of the light-emitting nanostructures in the NS-based CC layer 220 without the micro-LEDs 218 and a color point CP3 corresponding to the emission spectrum 326. The color point CP3 has chromaticity (x, y) coordinates of approximately (0.698, 0.302). Figure 3B Also shown is the color point CP4 of red of the DCI specification, which has chromaticity (x, y) coordinates of approximately (0.680, 0.320).

[0101] Figure 4A Another example dual PWL emission spectrum 422 of one or more of the red sub-pixels R1-R8 is shown, and Figure 4B The corresponding mixed color point CP5 on a portion of the 1931 CIE chromaticity diagram is shown. The configuration of the red sub-pixels R1-R8 in this example is different from Figure 3A-3BIn this example, (i) the NS-based CC layer 220 may have an optical density of about 0.3 and a thickness of about 5 μm, (ii) the micro-LED 218 may have a primary emission PWL of about 595 nm and a transmittance of about 50% at a PWL of about 595 nm, and (iii) the light-emitting nanostructure may have a primary emission PWL of about 640 and a FWHM of about 30 nm.

[0102] Similar to dual PWL emission spectrum 322, dual PWL emission spectrum 422 may have a first emission PWL 422A at approximately 640 nm and a second emission PWL 422B at approximately 595 nm. Figure 3A-3B 4A-4B, the peak intensity ratio of the first emission PWL 322A to the second emission PWL 322B is different from the peak intensity ratio of the first emission PWL 422A to the second emission PWL 422B. As a result, Figure 4B The mixed color point CP5 is different from Figure 3B The peak intensity ratio of the first emission PWL 422A to the second emission PWL 422B may be about 0.37, and the mixed color point CP5 has a chromaticity (x, y) coordinate of about (0.615, 0.385).

[0103] Figures 4A-4B Further illustrated is an example emission spectrum 426 of the light-emitting nanostructures in the NS-based CC layer 220 without the micro-LEDs 218 and a color point CP5 corresponding to the emission spectrum 326. The emission spectra 326 and 426 may be different due to different configurations of the NS-based CC layer 220.

[0104] Figure 5 Different examples of mixed color points CP7-CP12 on a portion of the 1931 CIE Chromaticity Diagram are shown for different optical densities of the NS-based CC layer 220 presented in Table 1 below.

[0105]

[0106] In some embodiments, the micro LED display device 200 may include other elements, such as a display screen, a diffusion layer, and a buffer layer, which are not shown for simplicity.

[0107] Example method for manufacturing a display device

[0108] Figure 6 6 is a flow chart of an example method 600 for manufacturing a micro-LED based display device 200 according to some embodiments. For illustrative purposes, reference will be made to the method for manufacturing a micro-LED based display device 200. Figure 2A-2CThe exemplary manufacturing process of the micro-LED based display device 200 shown in FIG. Figure 6 The operations shown in . Figure 7-10 600 is a cross-sectional view of a micro-LED-based display device 200 at various stages of manufacture according to some embodiments. The operations may be performed in a different order or not performed at all depending on the specific application. It should be noted that method 600 may not produce a complete micro-LED-based display device 200. Therefore, it should be understood that additional processes may be provided before, during, and after method 600, and some other processes may only be briefly described herein. Figure 2A-2C The same annotation as the element in Figure 7-10 The elements in are described above.

[0109] In step 605, micro LEDs of red, green, and blue sub-pixels are formed on a substrate. Figure 7 As shown in FIG. 2 , micro-LEDs 212 and 218 are formed on substrate 204. Micro-LEDs 214 are also formed, but in Figure 7 After forming micro-LEDs 212, 214, and 218, 206 may be formed on substrate 204, such as Figure 7 as shown in .

[0110] refer to Figure 6 In step 610, a NS-based CC layer is deposited on the micro-LED. Figure 8 As shown in Figure 7 The NS-based CC layer 820 is deposited on the structure of FIG. Similar to the NS-based CC layer 220, the NS-based CC layer 820 may include luminescent nanostructures, such as QDs in a UV-curable matrix material. In some embodiments, the NS-based CC layer 820 may be prepared by preparing a solution of luminescent nanostructures and spin coating the solution on the Figure 7 In some embodiments, the solution of the light-emitting nanostructures may include a tetraacrylate monomer.

[0111] Reference Figure 6 In step 615, a patterned mask layer is formed on the NS-based CC layer. Fig. 9 As shown in Figure 8 A patterned mask layer 928 is formed on the structure. In some embodiments, the patterned mask layer 928 may include a photoresist or any other suitable patternable mask material, which is clear to those skilled in the art. The patterned mask layer 928 may be formed by a photolithography process.

[0112] refer to Figure 6 In step 620, a hardening process is performed on the portion of the NS-based CC layer that is not covered by the patterned mask layer. Fig. 9 As shown in FIG, a hardening process is performed on portions of the NS-based CC layer 820 that are not covered by the patterned mask layer 928. The hardening process may include curing the exposed portions of the NS-based CC layer 820 with ultraviolet (UV) radiation at a temperature of about 100° C. to about 180° C. in air for a duration of about 60 minutes to about 120 minutes.

[0113] Reference Figure 6 In step 625, the portion of the NS-based CC layer not exposed to the hardening process is removed. Fig.10 As shown in FIG. 6 , portions of the NS-based CC layer 820 located below the patterned mask layer 928 during the hardening process of step 620 are removed to form the NS-based CC layer 220 on the micro LEDs 218. These uncured (hardened) portions of the NS-based CC layer 820 can be removed by washing with an alkaline solution after the hardening process. Fig. 9 to remove the structure.

[0114] Fig.11 1 is a flow chart of another example method 1100 for manufacturing a micro-LED based display device 200 according to some embodiments. For illustrative purposes, reference will be made to a method for manufacturing a micro-LED based display device 200. Figure 2A-2C The exemplary manufacturing process of the micro-LED based display device 200 shown in FIG. Fig.11 The operations shown in . Figure 12-17 1 is a cross-sectional view of a micro-LED-based display device 200 at various stages of manufacture according to some embodiments. The operations may be performed in a different order or not performed at all depending on the specific application. It should be noted that method 1100 may not produce a complete micro-LED-based display device 200. Therefore, it should be understood that additional processes may be provided before, during, and after method 1100, and some other processes may only be briefly described herein. Figure 2A-2C and Figure 7-10 The same annotation as the element in Figure 12-17 The elements in are described above.

[0115] In step 1105, micro LEDs of red, green, and blue sub-pixels are formed on a substrate. Fig.12 As shown in FIG. 2 , micro-LEDs 212 and 218 are formed on substrate 204. Micro-LEDs 214 are also formed, but in Fig.12 After forming micro-LEDs 212, 214, and 218, a dielectric layer 206 may be formed on substrate 204, such as Fig.12 as shown in .

[0116] refer to Fig.11In step 1110, a patterned template having openings on the micro LEDs of the red sub-pixels is formed. Figure 13-14 As stated in Fig.12 A patterned template 1330 having an opening 1432 is formed on the structure. The formation of the patterned template 1330 may include Fig.12 A photoresist layer 1330 is deposited on the structure, such as Fig.13 As shown in Fig.13 A photolithography process is performed on the structure to form an opening 1432, such as Fig.14 as shown in .

[0117] refer to Fig.11 In step 1115, a NS-based CC layer is deposited on the patterned template. Fig.15 As shown in Fig.14 The NS-based CC layer 1520 is deposited on the structure of . Similar to the NS-based CC layer 220, the NS-based CC layer 1520 may include luminescent nanostructures, such as QDs in a UV-curable matrix material. In some embodiments, the NS-based CC layer 1520 may be prepared by preparing a solution of luminescent nanostructures and spin coating the solution on Fig.14 In some embodiments, the solution of the light-emitting nanostructures may include a tetraacrylate monomer.

[0118] refer to Fig.11 In step 1120, a hardening process is performed on the portion of the NS-based CC layer in the opening. Fig.16 , a hardening process is performed on the portion of the NS-based CC layer 1520 in the opening 1432. The hardening process may include the following sequential operations: (i) masking the portion of the NS-based CC layer 1520 on the patterned template 1330 with a masking layer 1634, and (ii) curing the exposed portion of the NS-based CC layer 1520 in the opening 1432 with ultraviolet (UV) radiation at a temperature of about 100° C. to about 180° C. in air for a duration of about 60 minutes to about 120 minutes.

[0119] refer to Fig.11 In step 1125, the portion of the NS-based CC layer not exposed to the hardening process is removed. Fig.17 As shown in FIG. 1 , portions of the NS-based CC layer 1520 below the mask layer 1634 are removed during the hardening process of step 1120 to form the NS-based CC layer 220 on the micro LEDs 218. These uncured portions of the NS-based CC layer 1520 can be removed by washing with toluene after the hardening process. Fig.16 to remove the structure.

[0120] Exemplary Embodiments of Barrier-Coated Nanostructures

[0121] Fig.18 A cross-sectional structure of a light-emitting nanostructure (NS) 1800 coated with a barrier layer according to some embodiments is shown. In some embodiments, a group of NS 1800 may be included in a NS-based CC layer 136. NS 1800 coated with a barrier layer includes NS 1801 and a barrier layer 1806. NS 1801 includes a core 1802 and a shell 1804. Core 1802 includes a semiconductor material that emits light when absorbing higher energy. Examples of semiconductor materials for core 1802 include indium phosphide (InP), cadmium selenide (CdSe), zinc sulfide (ZnS), lead sulfide (PbS), indium arsenide (InAs), indium gallium phosphide (InGaP), cadmium zinc selenide (CdZnSe), zinc selenide (ZnSe) and cadmium telluride (CdTe). Any other II-VI, III-V, ternary or quaternary semiconductor structure exhibiting a direct band gap may also be used. In some embodiments, the core 1802 may further include one or more dopants such as metals, alloys, to provide some examples. Examples of metal dopants may include, but are not limited to, zinc (Zn), copper (Cu), aluminum (Al), platinum (Pt), chromium (Cr), tungsten (W), palladium (Pd), or combinations thereof. The presence of one or more dopants in the core 1802 may improve the structural and optical stability and QY of the NS 1801 compared to an undoped NS.

[0122] According to some embodiments, the core 1802 may have a size of less than 20 nm in diameter. In another embodiment, the core 1802 may have a size between about 1 nm and about 5 nm in diameter. Adjusting the size of the core 1802 and therefore the size of the NS 1801 in the nanometer range can achieve photoelectric emission coverage throughout the spectrum. Typically, larger NSs emit light toward the red end of the spectrum, while smaller NSs emit light toward the blue end of the spectrum. This effect occurs when larger NSs have more closely spaced energy levels than smaller NSs. This allows the NSs to absorb photons that include less energy, i.e., those photons that are closer to the red end of the spectrum.

[0123] Shell 1804 surrounds core 1802 and is disposed on an outer surface of core 1802. Shell 1804 may include cadmium sulfide (CdS), zinc cadmium sulfide (ZnCdS), zinc selenide sulfide (ZnSeS), and zinc sulfide (ZnS). In some embodiments, shell 1804 may have a thickness 1804t, for example, one or more monolayers. In other embodiments, shell 1804 may have a thickness 1804t between about 1 nm and about 5 nm. Shell 1804 may be used to help reduce the lattice mismatch with core 1802 and improve the QY of NS 1801. Shell 1804 may also help passivate and remove surface trap states on core 1802, such as dangling bonds, to increase the QY of NS 1801. The presence of surface trap states can provide non-radiative recombination centers and help reduce the emission efficiency of NS 1801.

[0124] In alternative embodiments, NS 1801 may include a second shell disposed on shell 1804, or two or more shells surrounding core 1802, without departing from the spirit and scope of the present invention. In some embodiments, the second shell may be about two monolayers thick, and is typically (although not necessarily) also a semiconductor material. The second shell may provide protection for core 1802. The second shell material may be zinc sulfide (ZnS), but other materials may also be used without departing from the scope or spirit of the present invention.

[0125] The barrier layer 1806 is configured to form a coating on the NS 1801. In some embodiments, the barrier layer 1806 is disposed on the outer surface 1804a of the housing 1804 and is substantially in contact with it. In embodiments of the NS 1801 having one or more shells, the barrier layer 1806 may be disposed on the outermost shell of the NS 1801 and is substantially in contact with it. In an exemplary embodiment, the barrier layer 1806 is configured to act as a spacer between the NS 1801 and one or more NS in, for example, a solution, a composition, and / or a film having a plurality of NSs, wherein the plurality of NSs may be similar to the NS 1801 and / or the barrier layer-coated NS 1800. In such NS solutions, NS compositions, and / or NS films, the barrier layer 1806 may help prevent the NS 1801 from aggregating with adjacent NSs. Aggregation of the NS 1801 with adjacent NSs may result in an increase in the size of the NS 1801, and thus result in a reduction or quenching of the optical emission properties of the aggregated NS (not shown) including the NS 1801. In other embodiments, barrier layer 1806 provides protection for NS 1801 from, for example, moisture, air, and / or harsh environments (e.g., high temperatures and chemicals used during photolithographic processing of the NS and / or during the manufacturing process of NS-based devices) that may adversely affect the structural and optical properties of NS 1801.

[0126] The barrier layer 1806 includes one or more materials that are amorphous, optically transparent, and / or electrically inert. Suitable barrier layers include inorganic materials, such as, but not limited to, inorganic oxides and / or nitrides. According to various embodiments, examples of materials for the barrier layer 1806 include oxides and / or nitrides of Al, Ba, Ca, Mg, Ni, Si, Ti, or Zr. In various embodiments, the barrier layer 1806 may have a thickness 1806t ranging from about 8 nm to about 15 nm.

[0127] like Fig.18 As shown in , according to some embodiments, the NS 1800 coated with a barrier layer may additionally or optionally include a plurality of ligands or surfactants 1808. According to some embodiments, the ligands or surfactants 1808 may be adsorbed or bound to the outer surface of the NS 1800 coated with a barrier layer, for example, on the outer surface of the barrier layer 1806. The plurality of ligands or surfactants 1808 may include a hydrophilic or polar head 1808a and a hydrophobic or non-polar tail 1808b. The hydrophilic or polar head 1808a may be bound to the barrier layer 1806. The presence of the ligands or surfactants 1808 may help NS 1800 and / or NS 1801 to separate from other NSs in, for example, a solution, a composition, and / or a film during its formation. If the NS is allowed to aggregate during its formation, the quantum efficiency of the NS, such as NS 1800 and / or NS 1801, may decrease. Ligands or surfactants 1808 may also be used to impart certain properties to the barrier-coated NS 1800, such as hydrophobicity, to provide miscibility in non-polar solvents, or to provide reactive sites for binding of other compounds (eg, reverse micellar systems).

[0128] There are a variety of ligands that can be used as ligand 1808. In some embodiments, the ligand is a fatty acid selected from lauric acid, caproic acid, myristic acid, palmitic acid, stearic acid and oleic acid. In some embodiments, the ligand is an organic phosphine or organic phosphine oxide selected from trioctylphosphine oxide (TOPO), trioctylphosphine (TOP), diphenylphosphine (DPP), triphenylphosphine oxide and tributylphosphine oxide. In some embodiments, the ligand is an amine selected from dodecylamine, oleylamine, hexadecylamine and octadecylamine. In some embodiments, the ligand is trioctylphosphine (TOP). In some embodiments, the ligand is oleylamine. In some embodiments, the ligand is diphenylphosphine.

[0129] There are a wide variety of surfactants that can be used as surfactant 1808. In some embodiments, nonionic surfactants can be used as surfactant 1808. Some examples of nonionic surfactants include polyoxyethylene (5) nonylphenyl ether (trade name IGEPAL CO-520), polyoxyethylene (9) nonylphenyl ether (IGEPAL CO-630), octylphenoxy poly(ethyleneoxy)ethanol (IGEPAL CA-630), polyethylene glycol oleyl ether (Brij 93), polyethylene glycol hexadecyl ether (Brij 52), polyethylene glycol octadecyl ether (Brij S10), polyoxyethylene (10) isooctylcyclohexyl ether (Triton X-100), and polyoxyethylene branched nonylcyclohexyl ether (Triton N-101).

[0130] In some embodiments, anionic surfactants may be used as surfactant 1808. Some examples of anionic surfactants include dioctyl sodium sulfosuccinate, sodium stearate, sodium lauryl sulfate, sodium monododecyl phosphate, sodium dodecylbenzene sulfonate, and sodium myristyl sulfate.

[0131] In some embodiments, NS1801 and / or 1800 can be synthesized to emit light in one or more various color ranges, such as red, orange, and / or yellow ranges. In some embodiments, NS1801 and / or 1800 can be synthesized to emit light in green and / or yellow ranges. In some embodiments, NS1801 and / or 1800 can be synthesized to emit light in blue, indigo, violet, and / or ultraviolet ranges. In some embodiments, NS1801 and / or 1800 can be synthesized to have a primary emission peak wavelength between about 605nm and about 650nm, between about 510nm and about 550nm, or between about 300nm and about 480nm.

[0132] NS1801 and / or 1800 can be synthesized to exhibit a high QY. In some embodiments, NS1801 and / or 1800 can be synthesized to exhibit a QY between 80% and 95% or between 85% and 90%.

[0133] Thus, according to various embodiments, NS 1800 may be synthesized such that the presence of the blocking layer 1806 on NS 1801 does not substantially alter or quench the optical emission properties of NS 1801.

[0134] Exemplary Embodiments of Nanostructure Films

[0135] Fig.19 A cross-sectional view of a NS film 1900 according to some embodiments is shown. In some embodiments, the NS-based CC layer 220 can be similar to the NS film 1900 .

[0136] According to some embodiments, the NS film 1900 may include a plurality of barrier layer coated core-shell NS 1800 ( Fig.18 ) and a matrix material 1910. According to some embodiments, the NS 1800 may be embedded or otherwise disposed in the matrix material 1910. As used herein, the term "embedded" is used to indicate that the NS is enclosed or wrapped within the matrix material 1910 that constitutes the main component of the matrix. It should be noted that in some embodiments, the NS 1800 may be uniformly distributed throughout the matrix material 1910, but in other embodiments, the NS 1800 may be distributed according to an application-specific uniformity distribution function. It should be noted that although the NS 1800 is shown as having the same diameter size, it will be understood by those skilled in the art that the NS 1800 may have a size distribution.

[0137] In some embodiments, NS 1800 may include a homogenous population of NS having a size that emits in a blue visible wavelength spectrum, a green visible wavelength spectrum, or a red visible wavelength spectrum. In other embodiments, NS 1800 may include a first NS population having a size that emits in a blue visible wavelength spectrum, a second NS population having a size that emits in a green visible wavelength spectrum, and a third NS population that emits in a red visible wavelength spectrum.

[0138] Matrix material 1910 can be any suitable host matrix material capable of accommodating NS1800. Suitable matrix materials can be chemically and optically compatible with NS1800 and any surrounding packaging materials or layers used to apply NS film 1900 to the device. Suitable matrix materials can include non-yellowing optical materials that are transparent to both primary and secondary light, thereby allowing both primary and secondary light to be transmitted through the matrix material. In some embodiments, matrix material 1910 can completely surround each of NS1800. In applications where a flexible or moldable NS film 1900 is required, matrix material 1910 can be flexible. Alternatively, matrix material 1910 can include a high-strength, non-flexible material.

[0139] The matrix material 1910 may include polymers and organic and inorganic oxides. Suitable polymers for use in the matrix material 1910 may be any polymer known to those of ordinary skill in the art to be useful for this purpose. The polymer may be substantially translucent or substantially transparent. The matrix material 1910 may include, but is not limited to, epoxies, acrylates, norbornenes, polyethylene, poly(vinyl butyral): poly(vinyl acetate), polyureas, polyurethanes; silicones and silicone derivatives, including but not limited to aminosilicones (AMS), polyphenylmethylsiloxanes, polyphenylalkylsiloxanes, polydiphenylsiloxanes, polydialkylsiloxanes, silsesquioxanes, fluorinated silicones, and vinyl and hydride substituted silicones; acrylic polymers and copolymers formed from monomers including but not limited to methyl methacrylate, butyl methacrylate, and lauryl methacrylate; styrene-based polymers such as polystyrene, aminopolystyrene (APS), and poly(acrylonitrile vinyl styrene) (AES); polymers crosslinked with difunctional monomers such as divinylbenzene; crosslinking agents suitable for crosslinking ligand materials, epoxides combined with ligand amines (e.g., APS or PEI ligand amines) to form epoxy resins, and the like.

[0140] In some embodiments, the matrix material 1910 includes scattering particles, such as TiO 2 microbeads, ZnS microbeads, or glass microbeads, which can improve the light conversion efficiency of the NS film 1900 .

[0141] In another embodiment, the matrix material 1910 may have low oxygen and moisture permeability, exhibit high light and chemical stability, exhibit a favorable refractive index, and adhere to the outer surface of the NS 1800, thereby providing a hermetic seal to protect the NS 1800. In another embodiment, the matrix material 1910 may be cured using UV or thermal curing methods to facilitate roll-to-roll processing.

[0142] According to some embodiments, NS film 1900 can be formed by mixing NS1800 into a polymer (e.g., a photoresist) and casting the NS-polymer mixture on a substrate, mixing NS1800 with monomers and polymerizing them together, mixing NS1800 into a sol-gel to form an oxide, or any other method known to those skilled in the art.

[0143] According to some embodiments, the formation of NS film 1900 may include a film extrusion process. The film extrusion process may include forming a uniform mixture of a core-shell NS (e.g., NS 1800) coated with a matrix material 1910 and a barrier layer, and introducing the uniform mixture into a hopper of an extruder mounted on the top. In some embodiments, the uniform mixture may be in the form of pellets. The film extrusion process may further include extruding the NS film 1900 from a slit die and passing the extruded NS film 1900 through a cooling roller. In some embodiments, the extruded NS film 1900 may have a thickness of less than about 75 μm, for example, in the range of about 70 μm to about 40 μm, about 65 μm to about 40 μm, about 60 μm to about 40 μm, or about 50 μm to about 40 μm. In some embodiments, the NS film 1900 has a thickness of less than 10 μm. In some embodiments, the formation of the NS film 1900 may optionally include a secondary process followed by a film extrusion process. The secondary process may include processes such as co-extrusion, thermoforming, vacuum forming, plasma treatment, molding, and / or embossing to provide texture to the top surface of the NS film 1900. The textured top surface NS film 1900 may help improve, for example, the defined optical diffusion properties and / or the defined angular optical emission properties of the NS film 1900.

[0144] Exemplary Embodiments of Luminescent Nanostructures

[0145] Various compositions having light-emitting nanostructures (NS) are described herein. Various properties of the light-emitting nanostructures, including their absorption properties, emission properties, and refractive index properties, can be tailored and tuned for various applications.

[0146] The material properties of the NS may be substantially homogeneous, or in certain embodiments, may be heterogeneous. The optical properties of the NS may be determined by their particle size, chemistry, or surface composition. The ability to adjust the size of the luminescent NS within a range between about 1 nm and about 15 nm may enable photoemission coverage across the spectrum to provide great versatility in color rendering. Particle encapsulation may provide robustness against chemical and UV deteriorating agents.

[0147] Any method known to those skilled in the art can be used to produce luminescent NS for the embodiments described herein. Suitable methods and example nanocrystals are disclosed in U.S. Patent No. 7,374,807; U.S. Patent Application Serial No. 10 / 796,832 filed on March 10, 2004; U.S. Patent Application No. 6,949,206; and U.S. Provisional Patent Application No. 60 / 578,236 filed on June 8, 2004, the disclosures of which are incorporated herein by reference in their entirety.

[0148] The light-emitting NS used in the embodiments described herein can be produced by any suitable material, including inorganic materials, and more preferably inorganic conductive or semiconductive materials. Suitable semiconductor materials may include those disclosed in U.S. Patent Application Serial No. 10 / 796,832, and may include any type of semiconductor, including II-VI, III-V, IV-VI and IV semiconductors. Suitable semiconductor materials may include, but are not limited to, Si, Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP, Bas, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SuS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si3N4, Ge3N4, Al2O3, (Al, Ga, In)2 (S, Se, Te) 3, Al 2 CO and suitable combinations of two or more such semiconductors.

[0149] In certain embodiments, the light-emitting NS may have a dopant selected from a p-type dopant or an n-type dopant. The NS may also have a II-VI or III-V semiconductor. Examples of II-VI or III-V semiconductor NS may include any combination of elements from Group II of the periodic table (e.g., Zn, Cd, and Hg) and any element from Group VI (e.g., S, Se, Te, and Po); and any combination of elements from Group III of the periodic table (e.g., B, Al, Ga, In, and Tl) and any element from Group V (e.g., N, P, As, Sb, and Bi).

[0150] The luminescent NS described herein may further include a ligand conjugated, coordinated, associated or attached to its surface. Suitable ligands may include any group known to those skilled in the art, including U.S. Patent No. 8,283,412; U.S. Patent Publication No. 2008 / 0237540; U.S. Patent Publication No. 2010 / 0110728; U.S. Patent No. 8,563,133; U.S. Patent No. 7,645,397; U.S. Patent No. 7,374,807; U.S. Patent No. 6,949,206; U.S. Patent No. 7,572,393; and U.S. Patent No. 7,267,875, the disclosures of which are incorporated herein by reference. The use of such ligands can enhance the ability of luminescent NS to bind to various solvents and matrices (including polymers). Increasing the miscibility (i.e., the ability to mix without separation) of luminescent NSs in various solvents and matrices can allow them to be distributed throughout the polymer composition so that the NSs do not aggregate together and, therefore, do not scatter light. Such ligands are described herein as "miscibility enhancing" ligands.

[0151] In certain embodiments, compositions having luminescent NS distributed or embedded in a matrix material are provided. Suitable matrix materials may be any material known to those of ordinary skill, including polymeric materials, organic and inorganic oxides. The compositions described herein may be layers, encapsulants, coatings, sheets, or films. It should be understood that in the embodiments described herein referring to layers, polymeric layers, matrices, sheets, or films, these terms are used interchangeably, and the embodiments described in this manner are not limited to any one type of composition, but rather encompass any matrix material or layer described herein or known in the art.

[0152] Down-converting NS (e.g., as disclosed in U.S. Pat. No. 7,374,807) exploits the emission properties of light-emitting nanostructures that are tailored to absorb light at a specific wavelength and then emit at a second wavelength, providing enhanced performance and efficiency of active sources (e.g., LEDs).

[0153] Although any method known to the skilled artisan can be used to produce luminescent NS, solution phase colloidal methods for controlled growth of inorganic nanomaterial phosphors can be used. See Alivisatos, A. P., "Semiconductor clusters, nanocrystals, and quantum dots," Science 271: 933 (1996); X. Peng, M. Schlamp, A. Kadavanich, A. P. Alivisatos, "Epitaxial growth of highly luminescent CdSe / CdS Core / Shell nanocrystals with photostability and electronic accessibility," J. Am. Chem. Soc., 1977, 35-43. Choo et al., J. Am. Chem. Soc. 30:7019-7029 (1997); and CB Murray, DJ Norris, MG Bawendi, "Synthesis and characterization ofnearly monodisperse CdE (E=sulfur, selenium, tellurium) semiconductornanocrystallites," J Am. Chem. Soc. 115:8706 (1993), the disclosures of which are incorporated herein by reference in their entirety.

[0154] According to some embodiments, CdSe can be used as a NS material, in one example, for visible light down-conversion, due to the relative maturity of the synthesis of this material. It can also replace NS without cadmium due to the use of universal surface chemistry.

[0155] In semiconductor NS, light-induced emission is caused by the band edge states of NS. The band edge emission from the luminescent NS competes with the radiation and non-radiative decay channels originating from the surface electronic states. X. Peng et al., J Am. Chem. Soc. 30: 7019-7029 (1997). As a result, the presence of surface defects such as dangling bonds provides non-radiative recombination centers and leads to reduced emission efficiency. An effective and permanent method for passivation and removal of surface trap states can be epitaxial growth of inorganic shell materials on the surface of NS. X. Peng et al., J. Am. Chem. Soc., 30: 7019-7029 (1997). The shell material can be selected so that the electronic energy level is type 1 relative to the core material (for example, having a larger band gap to provide a potential step that confines electrons and holes to the core). As a result, the probability of non-radiative recombination can be reduced.

[0156] Core-shell structure can be obtained by adding the organometallic precursor comprising shell material into the reaction mixture comprising core NS. In this case, it is not growth after the nucleation event, but the core acts as the core, and the shell can grow from its surface. The reaction temperature keeps lower to be conducive to the shell material monomer to add to the core surface, while preventing the independent nucleation of the nanocrystal of shell material. There is surfactant in the reaction mixture to guide the controlled growth of shell material and ensure solubility. When there is low lattice mismatch between two materials, a uniform and epitaxially grown shell can be obtained.

[0157] Example materials for preparing core-shell light-emitting NS may include, but are not limited to, Si, Ge, Sn, Se, Te, B, C (including diamond), P, Co, Au, BN, BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTc, BeS, BcSe, BcTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuP, CuCl, CuBr, CuI, Si3N4, Ge3N4, Al2O3, (Al, Ga, In)2(S, Se, Te)3, AlCO, and the shell luminescent NS used in the practice of the present invention include but are not limited to, (expressed as core / shell), CdSe / ZnS, InP / ZnS, InP / ZnSe, PbSe / PbS, CdSe / CdS, CdTe / CdS, CdTe / ZnS, etc.

[0158] The size of the light-emitting NS used in the embodiments described herein can be less than about 100nm, and as low as less than about 2nm, and the present invention absorbs visible light. As used herein, visible light is electromagnetic radiation with a wavelength between about 380 nanometers and about 780 nanometers visible to the human eye. Visible light can be separated into various colors of the spectrum, such as red, orange, yellow, green, blue, indigo and purple. Blue light can include light with a wavelength between about 435nm and about 495nm, green light can include light with a wavelength between about 495nm and 570nm, and red light can include light with a wavelength between about 620nm and about 750nm.

[0159] According to various embodiments, the light-emitting NS may have a size and composition such that they absorb photons in the ultraviolet, near infrared, and / or infrared spectra. The ultraviolet spectrum may include light between about 100 nm and about 400 nm, the near infrared spectrum may include light with wavelengths between about 750 nm and about 100 μm, and the infrared spectrum may include light with wavelengths between about 750 nm and about 300 μm.

[0160] Although luminescent NS of other suitable materials can be used in various embodiments described herein, in certain embodiments, NS can be ZnS, InAs, CdSe or any combination thereof to form a nanocrystal population for use in the embodiments described herein. As described above, in further embodiments, luminescent NS can be core / shell nanocrystals, such as CdSe / ZnS, InP / ZnSe, CdSe / CdS or InP / ZnS.

[0161] Suitable light-emitting nanostructures, methods of making light-emitting nanostructures, including the addition of various solubility-enhancing ligands, can be found in published US Patent Publication No. 2012 / 0113672, the disclosure of which is incorporated herein by reference in its entirety.

[0162] It should be understood that although certain embodiments have been shown and described herein, the claims are not limited to the specific forms or arrangements of parts described and shown. In the specification, illustrative embodiments have been disclosed, and although specific terms are employed, they are used only in a general and descriptive sense and not for the purpose of limitation. In view of the above teachings, modifications and variations of the embodiments are possible. Therefore, it should be understood that the embodiments may be implemented in a manner different from that specifically described.

Claims

1. Display devices, including: substrate; and A sub-pixel configured to emit display light having an emission spectrum including a first peak wavelength and a second peak wavelength, wherein the sub-pixel comprises: a nanostructure-based color conversion (NS-based CC) layer comprising quantum dots (QDs) configured to emit a first light having the first peak wavelength; and a micro LED disposed on the substrate and configured to emit a second light having the second peak wavelength, wherein the NS-based CC layer is disposed on the micro LED, wherein a first portion of the second light is absorbed by the QDs and down-converted into the first light, and Wherein a second portion of the second light is transmitted through the NS-based CC layer. 2 . The display device according to claim 1 , wherein the first peak wavelength is within a wavelength range of about 620 nm to about 750 nm. 3 . The display device according to claim 1 , wherein the second peak wavelength is within a wavelength range of about 550 nm to about 610 nm. 4 . The display device of claim 1 , wherein the first peak wavelength and the second peak wavelength are in different and adjacent wavelength regions of an electromagnetic (EM) spectrum.

5. The display device of claim 1, wherein the first peak wavelength is in a red wavelength region of an electromagnetic (EM) spectrum, and the second peak wavelength is in an orange or yellow wavelength region of the EM spectrum. The display device according to claim 1 , wherein an intensity of the first peak wavelength is greater than an intensity of the second peak wavelength.

7. The display device of claim 1, wherein a peak intensity ratio of the first peak wavelength to the second peak wavelength ranging from about 0 to about 40 corresponds to an optical transmittance of the micro LED at the second peak wavelength ranging from about 100% to about 1%.

8. The display device of claim 1, wherein the emission spectrum corresponds to a single color point having a first chromaticity (x, y) coordinate on an RGB color space.

9. The display device of claim 8, wherein a peak intensity ratio of the first peak wavelength to the second peak wavelength ranging from about 0 to about 40 corresponds to a first chromaticity (x, y) coordinate ranging from about (0.6, 0.4) to about (0.7, 0.3), respectively.

10. The display device of claim 8, wherein the optical density of the NS-based CC layer ranging from about 0 to about 3.0 corresponds to first chromaticity (x, y) coordinates ranging from about (0.6, 0.4) to about (0.7, 0.3), respectively. 11 . The display device of claim 1 , wherein an optical transmittance of the micro LED at the second peak wavelength ranging from about 100% to about 1% corresponds to an optical density of the NS-based CC layer ranging from about 0 to about 3.

0.

12. The display device of claim 1 , wherein the emission spectrum corresponds to a single color point having a first chromaticity (x, y) coordinate along a coordinate line between a second chromaticity (x, y) coordinate of approximately (0.5, 0.5) and a third chromaticity (x, y) coordinate of approximately (0.7, 0.3) of an RGB color space. 13 . The display device of claim 1 , wherein the micro LED has a light transmittance of about 1% to about 70% through the NS-based CC layer at the second peak wavelength. 14 . The display device of claim 1 , wherein the NS-based CC layer comprises a surface area of ​​about 0.5 μm×about 0.5 μm to about 1000 μm×about 1000 μm. 15 . The display device of claim 1 , wherein the NS-based CC layer covers an entire top surface area of ​​the micro LED. 16 . The display device of claim 1 , wherein a top surface area of ​​the NS-based CC layer is larger than a top surface area of ​​the micro LED. 17 . The display device of claim 1 , wherein the NS-based CC layer comprises a thickness of about 5 μm to about 40 μm. 18 . The display device of claim 1 , wherein the NS-based CC layer comprises an optical density of about 0.1 to about 3.

0.

19. The display device according to claim 1 further comprises a second sub-pixel, the second sub-pixel comprising a second micro-LED disposed on the substrate, wherein the second micro-LED is configured to emit a second display light having an emission spectrum having a single peak wavelength within a wavelength range of about 495 nm to about 570 nm of the electromagnetic (EM) spectrum.

20. The display device of claim 1, further comprising a second sub-pixel comprising a second micro-LED disposed on the substrate, wherein the second micro-LED is configured to emit a second display light having an emission spectrum having a single peak wavelength within a wavelength range of approximately 435 nm to approximately 495 nm of an electromagnetic (EM) spectrum.

21. Display devices, including: substrate; A first sub-pixel configured to emit a first display light having a first emission spectrum including a first peak wavelength and a second peak wavelength, wherein the first sub-pixel comprises: a first nanostructure-based color conversion (NS-based CC) layer comprising a first set of quantum dots (QDs) configured to emit a first light having the first peak wavelength, and a first micro LED disposed on the substrate and configured to emit a second light having the second peak wavelength, wherein the NS-based CC layer is disposed on the first micro LED; and The second sub-pixel is configured to emit second display light having a second emission spectrum including a third peak wavelength and a fourth peak wavelength, wherein the third peak wavelength and the fourth peak wavelength are different from the first peak wavelength and the second peak wavelength, respectively, and The second sub-pixel comprises: a second NS-based CC layer including a second set of quantum dots (QDs) configured to emit a third light having the third peak wavelength, and A second micro LED disposed on the substrate is configured to emit a fourth light having the fourth peak wavelength, wherein the second NS-based CC layer is disposed on the second micro LED.

22. The display device of claim 21, wherein the first emission spectrum corresponds to a first color point having a first chromaticity (x, y) coordinate on an RGB color space, and The second emission spectrum corresponds to a second color point having a second chromaticity (x, y) coordinate in the RGB color space, and the second chromaticity (x, y) coordinate is different from the first chromaticity (x, y) coordinate. 23 . The display device according to claim 21 , wherein the first peak wavelength and the third peak wavelength are within a wavelength range of about 620 nm to about 750 nm. 24 . The display device of claim 21 , wherein the second peak wavelength and the fourth peak wavelength are within a wavelength range of about 550 nm to about 610 nm. 25 . The display device of claim 21 , wherein an optical density of the first NS-based CC layer is different from an optical density of the second NS-based CC layer. 26 . The display device of claim 21 , wherein a thickness of the first NS-based CC layer is different from a thickness of the second NS-based CC layer.

27. The display device of claim 21, wherein a concentration of the first set of QDs is different from a concentration of the second set of QDs.

28. The display device of claim 21, wherein a first portion of the second light is absorbed by the first set of QDs and down-converted into the first light, and Wherein a second portion of the second light is transmitted through the first NS-based CC layer.

29. The display device of claim 21, wherein a first portion of the fourth light is absorbed by the second group of QDs and down-converted into the third light, and Wherein a second portion of the fourth light is transmitted through the second NS-based CC layer.

30. The display device of claim 21, wherein the first micro LED has a first optical transmittance through the first NS-based CC layer at the second peak wavelength of about 1% to about 70%, and Wherein the second micro LED has a second optical transmittance of about 1% to about 70% through the second NS-based CC layer at the fourth peak wavelength, the second optical transmittance being different from the first optical transmittance.

31. A method for manufacturing a display device, comprising: forming a first micro LED and a second micro LED on a substrate, wherein the first micro LED is formed to emit a first display light having a first emission spectrum including a double peak wavelength, and the second micro LED is formed to emit a second display light having a second emission spectrum including a single peak wavelength; depositing a quantum dot (QD) layer on the first micro-LED and the second micro-LED; masking a first portion of the QD layer; performing a hardening process on a second portion of the QD layer; and The first portion of the QD layer is removed.

32. The method of claim 31, wherein depositing a QD layer comprises spin coating, slot die coating, doctor blade coating, or rod coating a solution of QDs on the first microLED and the second microLED.

33. The method of claim 31, wherein masking the first portion of the QD layer comprises selectively forming a photoresist layer on the first portion of the QD layer on the second micro LED.

34. The method of claim 31, wherein performing a hardening process on a second portion of the QD layer comprises curing the second portion of the QD layer on the first micro LED with ultraviolet radiation.

35. The method of claim 31, wherein removing the first portion of the QD layer comprises washing the first portion of the QD layer in an alkaline solution.

36. A method for manufacturing a display device, comprising: forming a first micro LED and a second micro LED on a substrate, wherein the first micro LED is formed to emit a first display light having a first emission spectrum including a double peak wavelength, and the second micro LED is formed to emit a second display light having a second emission spectrum including a single peak wavelength; forming a patterning template over the first micro LED and the second micro LED, wherein the patterning template comprises an opening over the first micro LED; depositing a quantum dot (QD) layer on the patterned template; masking a first portion of the QD layer; performing a hardening process on a second portion of the layer of QDs; and A first portion of the QD layer is removed.

37. The method of claim 36, wherein: Forming a patterned template includes: depositing a polymer layer over the first micro-LED and the second micro-LED; and The polymer layer is patterned to form the opening over the first micro LED.

38. The method of claim 36, wherein depositing a QD layer comprises spin coating, slot die coating, doctor blade coating, or rod coating a solution of QDs on the patterned template.

39. The method of claim 36, wherein performing a hardening process on the second portion of the QD layer comprises curing the second portion of the QD layer disposed in the opening with ultraviolet radiation.

40. The method of claim 36, wherein removing the first portion of the QD layer comprises washing the first portion of the QD layer in toluene.

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