Ultra-high density quantum dot color converter

Abstract

To provide quantum dot-based color converters having a high density of sub-pixels.SOLUTION: A color converter for an ultra-dense light-emitting diode array comprises a substrate and a color conversion layer. The color conversion layer comprises a first group of sub-pixels overlying the substrate. The first group of sub-pixels comprises a first plurality of quantum dots. The first plurality of sub-pixels emit light within a first wavelength range. Each sub-pixel independently includes: a volume less than 30 μm3; a thickness from 1 μm to 3 μm; a pitch less than 5 μm; and a density of the quantum dots within the volume from 10 vol.% to 50 vol.%, where vol.% is based on dividing the total volume of quantum dots minus any ligands or other interstitial materials by the total volume of the sub-pixel.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a quantum dot color converter having high-density pixels. The pixels have high-density quantum dots. The color converter can be used in optical displays. [Background technology]

[0002] Arrays of quantum dot-containing pixels illuminated by LEDs are widely used in displays. Reducing the size of quantum dot-containing pixel arrays for use in applications such as integrated contact lens displays presents unique challenges.

[0003] The drawings described herein are for illustrative purposes only. They are not intended to limit the scope of this disclosure. [Brief explanation of the drawing]

[0004] [Figure 1] Examples of green, red, and blue subpixels provided by this disclosure are shown below. [Figure 2] Examples of green, red, and blue subpixels incorporating lower and upper Bragg reflectors, as provided by this disclosure, are shown. [Figure 3A] This shows an example of blue light transmitted through an array of subpixels with different diameters and pitches. [Figure 3B] This shows an example of blue light transmitted through an array of subpixels with different diameters and pitches. [Figure 3C] This shows an example of blue light transmitted through an array of subpixels with different diameters and pitches. [Figure 3D] This shows an example of blue light transmitted through an array of subpixels with different diameters and pitches. [Figure 3E] This shows an example of blue light transmitted through an array of subpixels with different diameters and pitches. [Figure 3F] This shows an example of blue light transmitted through an array of subpixels with different diameters and pitches. [Figure 3G] This shows an example of blue light transmitted through an array of subpixels with different diameters and pitches. [Figure 3H] This shows an example of blue light transmitted through an array of subpixels with different diameters and pitches. [Figure 3I] This shows an example of blue light transmitted through an array of subpixels with different diameters and pitches. [Figure 3J] This shows an example of blue light transmitted through an array of subpixels with different diameters and pitches. [Figure 4] This shows blue light transmitted through an array of 1.4 μm diameter subpixels with a pitch of 2.8 μm. [Figure 5A] This shows blue light transmitted through an array of 9.6 μm diameter subpixels with a 12.5 μm pitch. [Figure 5B] This image shows green emission from an array of 9.6 μm diameter quantum dot-containing subpixels with a 12.5 μm pitch and a thickness (depth) of 2 μm. The green quantum dot array can be pumped by the underlying blue subpixel array. [Figure 5C] This image shows red emission from an array of 9.6 μm diameter quantum dot-containing subpixels with a 12.5 μm pitch and a thickness (depth) of 2 μm. The red quantum dot array is pumped by the underlying blue subpixel array. [Figure 6A] This shows blue light transmitted through an array of 1.4 μm diameter blue subpixels with a pitch of 2.8 μm and a thickness (depth) of 2 μm. [Figure 6B] This exhibits green emission through an array of 1.4 μm diameter green quantum dot-containing subpixels with a pitch of 2.8 μm and a thickness (depth) of 2 μm. [Figure 6C]It shows green light emission through an array of 1.4 μm diameter red quantum dot-containing subpixels having a pitch of 2.8 μm and a thickness (depth) of 2 μm. [Figure 7] An example of a color conversion layer provided by the present disclosure is shown. [Figure 8A] An example of the steps used to manufacture a quantum dot color converter provided by the present disclosure is shown. [Figure 8B] An example of the steps used to manufacture a quantum dot color converter provided by the present disclosure is shown. [Figure 8C] An example of the steps used to manufacture a quantum dot color converter provided by the present disclosure is shown. [Figure 8D] An example of the steps used to manufacture a quantum dot color converter provided by the present disclosure is shown. [Figure 8E] An example of the steps used to manufacture a quantum dot color converter provided by the present disclosure is shown. [Figure 8F] An example of the steps used to manufacture a quantum dot color converter provided by the present disclosure is shown. [Figure 9] An array of subpixels and a pixel including subpixels of different colors are shown.

Best Mode for Carrying Out the Invention

[0005] The numerical ranges and parameters that describe the broad scope of the present invention are approximate values, and although the numerical values described in specific examples are reported as accurately as possible, any numerical value inherently includes certain errors that occur inevitably in the standard variations found in their respective test measurements, individual variations, and / or daily variations.

[0006] Furthermore, it should be understood that any numerical range listed herein is intended to include all subranges contained within it. For example, the range "1 to 10" is intended to include all subranges having a minimum value of 1 to a maximum value of 10 (including the listed values), i.e., a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0007] A "color converter" refers to a structure configured to convert the wavelength of incident radiation, such as light from an array of blue light-emitting diodes (LEDs), into light within one or more different wavelength ranges, such as light within the wavelength ranges of green and red. A color converter may include multiple layers, including a color conversion layer containing multiple pixels and multiple subpixels, and one or more other layers such as a passivation layer, a reflection layer, a crosstalk minimization layer, and / or a focusing layer.

[0008] A color conversion element refers to a volume containing multiple quantum dots. For example, a color conversion element may contain multiple quantum dots that can convert blue light into red and / or green light.

[0009] The "red wavelength range" refers to the wavelength range of 565nm to 650nm.

[0010] The "far-red wavelength range" refers to the wavelength range of 650 nm to 750 nm.

[0011] The "green wavelength range" refers to the wavelength range of 515nm to 565nm.

[0012] The "blue wavelength range" refers to the wavelength range of 405nm to 475nm.

[0013] A "subpixel" refers to an individually addressable element of a display device. A subpixel can include a color converter and, optionally, one or more material layers beneath the color converter and / or one or more material layers above the color converter. The one or more underlying and / or above material layers can perform one or more functions. For example, the underlying layers can function as a substrate, a wavelength-selective filter, or a layer designed to minimize crosstalk between pixels and subpixels. The above material layers can function, for example, as a passivation layer, a wavelength-selective filter, or a lens.

[0014] A "pixel" refers to a group of subpixels that repeat across the display. For example, a pixel can contain 2 to 6 subpixels, such as 2, 3, 4, 5, or 6 subpixels. A pixel can contain, for example, red subpixels, green subpixels, and blue subpixels. Other color combinations are also possible.

[0015] Quantum dot-containing subpixels are widely used in displays.

[0016] For certain applications, ultra-high-density quantum dot full-color converters may be desirable to have a thickness of less than 2 μm with subpixels having a pitch of less than 2 μm. Fabricating quantum dot subpixels with high overall conversion efficiency at these dimensions and integrating ultra-high-density quantum dot color converters into robust, miniaturized optical displays requires the use of specialized materials and processes.

[0017] An optical display may include a quantum dot color converter on top of an LED array. The color converter may include an array of subpixels. Certain subpixels may include quantum dots that can convert incident light in a first wavelength range into emitted light in a second wavelength range. For example, in the context of a display, incident blue light may be converted into emitted light in the red wavelength range, other subpixels may include quantum dots that can emit light in the green wavelength range when irradiated with light in the blue wavelength range, and other subpixels may be transparent to light in the blue wavelength range. Each subpixel may be aligned with a corresponding blue-emitting LED in the LED array.

[0018] Ultra-high density optical displays, such as optical displays with subpixel pitches of less than 5 μm, may be useful in portable electronic devices and contact lens arrays. Contact lenses incorporating optical displays are described, for example, in U.S. Patent Publication No. 2018 / 0149884. Ultra-high density optical displays, particularly optical displays for contact lenses, present unique design requirements. It is well known that displays "look sharp" at pixel densities exceeding 1 pixel per second (Snellen 20 / 20). Snellen 20 / 20 is not "perfect" human vision, but it is close to the average for adults in their 60s. Young adults without visual impairment have visual acuity of 20 / 16 to 20 / 12. Snellen 20 / 12 corresponds to 100 pixels / degree, adding further constraints to pixel size. Since angular resolution is defined in pixels / degree, the closer the display is to the eye, the higher the pixel PPI (pixels per linear inch) of the display must be to achieve the desired Snellen angular resolution. QLED televisions have a pixel pitch of approximately 150 μm to accommodate a viewing distance of approximately 2 meters, and the thickness of the quantum dot-containing color conversion film is approximately 15 μm. Mobile phones have a pixel pitch of approximately 55 μm to accommodate a viewing distance of approximately 0.3 meters. A display on a headset viewed from a distance of approximately 0.04 meters can have a pixel pitch of approximately 9 μm. A display on a contact lens approximately 25 mm from the retina should have a pixel pitch of approximately 1.8 μm to meet the 60 pixels / degree measurement standard for 20 / 20 visual acuity over a field of view of approximately 5 degrees at a magnification of 3x from the contact lens display to the retinal image. An example of a pixel containing four subpixels is shown in Figure 9.

[0019] Increased PPI and pixel pitch can affect the requirements of the color conversion layer. Color conversion efficiency is defined as the number of color-converted photons in the red, green, or other wavelength range emitted from a particular color-converted subpixel divided by the number of pump photons, such as blue or ultraviolet photons, that collide with the color conversion layer, and depends on the distance between the quantum dot and the material separating the quantum dot. A small number of pump photons may leave the display and desaturate the color purity. Color conversion purity is a measure of the purity of the light emanating from a particular color-converted subpixel and is defined as the number of color-converted photons divided by the total number of photons emanating from that particular color-converted subpixel, including both color-converted and pump photons. For example, for a red-converted subpixel, the purity of color conversion is defined as the number of red photons emanating from the red subpixel divided by the sum of the number of red photons present in the same red subpixel plus the number of pump photons, such as blue photons. For both color conversion efficiency and color conversion purity, an increase to 100% is desirable, and both metrics become more difficult as pixel size and thickness decrease. Color conversion purity is a strong function of the optical properties of a particular quantum dot and the density of quantum dots in the color conversion film. As the pixel width decreases from that of a QLED television display with a subpixel size of approximately 75 μm to less than approximately 2 μm for ultra-high-density contact lens displays, maintaining 15 μm thick quantum dot-containing subpixels becomes impractical, as this presents a challenge in manufacturing quantum dot-containing subpixels with high aspect ratios. Furthermore, for certain applications such as contact lens displays, it is desirable to make the display as thin as possible. To meet practical manufacturing and thin-screen display objectives, a subpixel height of 2 μm or less may be desirable. Then, in order to maintain an acceptable color conversion efficiency of over approximately 50% and an acceptable color conversion purity of over approximately 80%, the density of quantum dots in high-aspect-ratio subpixels must be increased.However, the practical density of quantum dots may be limited by Foster resonance energy transfer between adjacent quantum dots, which requires adjacent quantum dots to be uniformly spaced at approximately 5 nm to 10 nm apart to mitigate the effects of Foster resonance energy transfer (FRET). Energy transfer to other subpixel elements, such as metal sidewalls, can also reduce efficiency. A color converter having a total thickness of less than approximately 10 μm, as well as a color conversion layer comprising multiple subpixels having a pitch of less than approximately 2 μm and a subpixel width of less than approximately 2 μm, is provided by this disclosure.

[0020] The challenges of creating an ultra-high density color converter include providing a coating on quantum dots that enables high-density quantum dot packing and minimizes FRET, developing structures and processes that can provide RGB (red / green / blue) subpixels with a pitch of less than 5 μm and a PPI greater than 10,000 (a 6.4 μm pitch is approximately 3,900 PPI, and a 1.3 μm pitch is approximately 19,500 PPI), and providing an accurate color gamut with acceptable dark levels and low inter-subpixel crosstalk.

[0021] The color converter provided in this disclosure may include multiple layers, including a color conversion layer. For example, the color converter may include a substrate layer, a color conversion layer on the substrate layer, a passivation layer on the color conversion layer, and optionally additional layers such as a reflective layer and a lens layer.

[0022] The color conversion layer may include multiple subpixels, and at least some of these subpixels may include multiple quantum dots.

[0023] The volume fraction of quantum dots within a pixel can be 10% to 70%, 10% to 50%, 10% to 40%, 10% to 30%, or 10% to 20%.

[0024] The color conversion layer may have a thickness of, for example, less than 20 μm, less than 15 μm, less than 10 μm, or less than 5 μm.

[0025] A color conversion layer containing multiple subpixels is, for example, 0.2 mm. 2 ~10mm 2 It can have an area of ​​.

[0026] The color conversion layer can have a linear dimension of, for example, 0.2 mm to 1.5 mm.

[0027] An example of a color conversion layer is shown in Figure 1. Figure 1 shows a silicon CMOS circuit 101 interconnected to an LED array 102 above. The color conversion layer 103 consists of a layer containing multiple subpixels 104, an underlying passivation layer 105, and an upper passivation layer 106. Each LED is aligned to an individual subpixel. The pixel layer 104 contains green subpixels 104a and red subpixels 104b, each containing multiple green and red quantum dots, and further includes a blue subpixel 104c configured to transmit light in the blue wavelength range emitted by the LED array 102. The color conversion layer 103 can be, for example, 2 μm thick.

[0028] A color conversion layer can be configured to convert incident light within an incident wavelength range into emitted light within one or more emission wavelength ranges. In the case of an optical display, the incident light may be within the blue wavelength range, and multiple subpixels may be selected to provide an acceptable color gamut for visual display. A four-color display designed to produce 100% REC2020 may, for example, include red, green, blue, and cyan subpixels. A four-color display designed to preserve night vision may add a deep red (DR) subpixel with a peak emission wavelength above approximately 720 nm.

[0029] For certain applications, it may be desirable that the color converter provided by this disclosure exhibits a quantum conversion efficiency of more than 80% from 455 nm blue light to green or red light, that green and red subpixels have less than 2% blue leakage through the green and red subpixels, that the layer thickness is less than 2 μm, that the subpixels are arranged at a pitch of 3.3 μm or less, that the crosstalk or annihilation ratio between adjacent subpixels may be less than 1000:1, and that the color conversion layer is compatible with SiO2 sealant technology and other dielectric films configured to provide a seal over a useful time frame.

[0030] In a specific color conversion layer, blue light from an LED array can be transmitted through blue-transmitting subpixels. In a specific color converter, the LEDs can emit light in the wavelength range of 400nm to 430nm, and the blue subpixels may include multiple quantum dots that absorb light in the wavelength range of 400nm to 430nm and emit light in the blue wavelength range of, for example, 450nm to 490nm.

[0031] In certain color converters, the LED array can emit light in the near-ultraviolet wavelength range, for example, 300 nm to 400 nm, or other suitable wavelength ranges.

[0032] In a specific color converter, the LED array can emit light in the near-infrared wavelength range, for example, 780nm to 1700nm, or other suitable wavelength ranges, while quantum dots can absorb multiple low-energy photons and upconvert them to the desired visible wavelength.

[0033] In certain color conversion layers, all or some of multiple subpixels may contain quantum dots that can emit light in the red to near-infrared wavelength range, such as 650nm to 750nm. Near-infrared displays may be useful for night vision applications.

[0034] A color conversion layer can contain multiple pixels. For example, a color conversion layer can contain 1,000 to 1,000,000 pixels, 5,000 to 500,000 pixels, or 10,000 to 100,000 pixels. A color conversion layer can contain, for example, more than 1,000 pixels, more than 5,000 pixels, more than 10,000 pixels, more than 100,000 pixels, or more than 1,000,000 pixels.

[0035] The color conversion layer may contain pixels that emit a single color, or it may contain groups of subpixels, each group of subpixels emitting within a different wavelength range. Any suitable number of groups of subpixels emitting within different wavelength ranges can be used. An example of a pixel containing four subpixels is shown in Figure 9, where the subpixels emit within the wavelength ranges of red, green, blue, and cyan. Figure 9 shows an array of hexagonal subpixels 901. Pixel 902 contains a red subpixel 901a, a cyan subpixel 901b, a green subpixel 901c, and a blue subpixel 901d.

[0036] Multiple subpixels can be configured to convert incident light within a first wavelength range into emitted light within one or more wavelength ranges. For example, the incident light may be in the blue wavelength range, and the emitted light may be in the red, green, deep red, and blue wavelength ranges.

[0037] Multiple subpixels can also be configured without any color conversion layers so that the incident pump wavelength is emitted directly from the subpixel. For example, referring to Figure 9, a blue subpixel can contain blue light emitted by a blue pump LED, or it can be the blue emission of a subpixel containing a blue emission quantum dot.

[0038] Subpixels can have maximum in-plane dimensions of, for example, 1 μm to 4 μm, 1 μm to 3 μm, or 1 μm to 2 μm.

[0039] The sub-pixel can have a maximum in-plane dimension of, for example, less than 5 μm, less than 4 μm, less than 3 μm, less than 2 μm, or less than 1 μm.

[0040] The sub-pixel can have a depth of, for example, 0.5 μm to 4 μm, 0.5 μm to 4 μm, 0.5 μm to 3 μm, or 0.5 μm to 2 μm.

[0041] The sub-pixel can have a height of, for example, 0.5 μm to 3 μm and a width of 0.5 μm to 3 μm, a height of 1 μm to 3 μm and a width of 1 μm to 3 μm, or a height of 1 μm to 2 μm and a width of 1 μm to 2 μm.

[0042] The sub-pixel can have a depth that is the same as or greater than the maximum in-plane dimension.

[0043] The sub-pixel can have an aspect ratio of, for example, 12:1 to 1:12, 10:1 to 1:10, 8:1 to 1:8, 6:1 to 1:6, 4:1 to 1:4, 3:1 to 1:3, 2:1 to 1:2, or 1.5:1 to 1:1.5.

[0044] The sub-pixel can have an aspect ratio (height:width) of, for example, greater than 1:1, greater than 2:1, greater than 4:1, greater than 6:1, greater than 8:1, greater than 10:1, or greater than 12:1. The sub-pixel can have an aspect ratio (height:width) of, for example, less than 12:1, less than 10:1, less than 8:1, less than 5:1, less than 4:1, less than 3:1, less than 2:1, less than 1:1, less than 0.5:1, or less than 0.2:1.

[0045] The sub-pixel can be, for example, 0.1 μm 3 ~70 μm 3 、1 μm 3 ~64 μm 3 、3 μm 3 ~40 μm 3 、6 μm 3 ~50 μm 3 、または10 μm 3 ~40 μm3 It can have a volume of, for example, 70 μm. 3 Less than 60 μm 3 Less than 50 μm 3 Less than 40 μm 3 Less than 30 μm 3 Less than 20 μm 3 Less than 10 μm 3 Less than 1 μm, or 1 μm 3 It can have a volume less than [a certain value].

[0046] Subpixels can have aspect ratios (height:width) of 10:1 to 2:1, 8:1 to 2:1, 6:1 to 2:1, or 4:1 to 2:1, and heights of 0.5 μm to 3 μm, or 1 μm to 3 μm.

[0047] Subpixels can have aspect ratios (height / width) of 10:1 to 2:1, 8:1 to 2:1, 6:1 to 2:1, or 4:1 to 2:1, and widths of 1 μm to 3 μm, or 1 μm to 2 μm.

[0048] Subpixels can have aspect ratios (height / width) of 16:1-4:1, 12:1-4:1, 10:1-4:1, 8:1-4:1, or 6:1-4:1, and heights of 0.5 μm-3 μm, or 1 μm-3 μm.

[0049] Subpixels can have aspect ratios (height / width) of 16:1-4:1, 12:1-4:1, 10:1-4:1, 8:1-4:1, or 6:1-4:1, and widths of 1 μm-3 μm, or 1 μm-2 μm.

[0050] This is comparable to the approximately 1:2 aspect ratio (height / width) of 20μm pitch quantum dot LEDs used in television displays.

[0051] A subpixel can have any suitable cross-sectional profile. For example, a subpixel can have a square cross-sectional profile, a hexagonal cross-sectional profile, or a circular cross-sectional profile.

[0052] A subpixel can have a width of, for example, 0.5 μm to 10 μm, and the subpixel area can be, for example, 0.2 μm. 2 ~30μm 2 It can be.

[0053] Subpixels can be bounded by materials such as inorganic or organic materials.

[0054] The material that borders the subpixels can be selected to be non-absorbent to visible radiation, such as radiation in the red, green, and blue wavelength ranges, to withstand subsequent processing temperatures, and / or to reflect radiation in the red, green, and blue wavelength ranges.

[0055] Examples of suitable inorganic materials include semiconductors, metals, and metal alloys. For example, the material that borders the subpixels may include aluminum.

[0056] Suitable examples of organic materials include polymers, polymer composites, thermally conductive polymer composites, or conductive polymer composites.

[0057] Subpixels may include cavities or well-defined cavities within a thin film, such as cavities within an aluminum thin film.

[0058] Subpixels may include features deposited or constructed on a substrate, where the spaces between adjacent subpixels are filled with material. Subpixels can be defined by cavities created by removal processes, including, for example, chemical-based processes such as chemical etching, physical-based processes such as ion milling, or combinations thereof such as plasma etching. Subpixels can also be defined by cavities created by layering processes, including, for example, chemical-based processes such as electrochemical plating, physical-based processes such as physical vapor deposition, evaporation, or sputtering, or combinations thereof such as atomic layer deposition, chemical vapor deposition, or laser-induced plating.

[0059] Multiple subpixels may include multiple color-converting elements arranged on a common substrate. For example, the common substrate may be an aluminum layer. The color-converting elements may be defined as cavities or wells within the aluminum substrate, resulting in sidewalls containing aluminum. The bottom of the subpixel may include a transparent material, such as a blue-transmitting material, to allow illumination of the subpixel by a blue-emitting LED. The color-converting elements may be defined by the material between the substrate and the color-converting elements. The substrate and the separating material may be the same or different.

[0060] Subpixels may have vertical or non-vertical sidewalls. The sidewalls may be configured to facilitate forward light scattering. The sidewalls may be configured to be reflective to light from the LED and / or to light emitted by quantum dots within the subpixel.

[0061] The sidewalls of a subpixel can be configured to reflect, scatter, and / or guide light to control the far-filed emission pattern of light emitted / transmitted by the subpixel. For example, the subpixel sidewalls can be structured to reflect or guide light at the excitation wavelength of the quantum dot and / or light emitted by the quantum dot. This can be achieved by coating the sidewalls of the subpixel with a material having different refractive indices at the excitation and emission wavelengths.

[0062] A subpixel can be configured to convert incident light within a first wavelength range into light within a second wavelength range. Other subpixels can be configured to transmit light through them. This is shown in Figure 1, where subpixels 104a and 104b convert blue light to green and red light, respectively, and pixel 104c transmits blue light.

[0063] Color conversion subpixels can include multiple quantum dots. Transmission subpixels can include materials that do not absorb incident radiation.

[0064] The transparent subpixel may include a material configured to modify its transparent pattern to resemble the emission pattern of the color-transforming subpixel.

[0065] Quantum dots are semiconductor materials whose electrical and optical properties differ from those of bulk materials due to quantum constraint effects, exhibiting different sizes, compositions, and structures. Fluorescence in quantum dots arises from the excitation of valence electrons through light absorption, followed by emission at lower energy wavelengths when the excited electrons return to the ground state. Quantum constraints create an energy difference between the valence band and the conduction band, depending on the size, composition, and structure of the quantum dot. For example, larger quantum dots have lower energy fluorescence spectra. The photoluminescence emission wavelength of quantum dots can exhibit sharp emission spectra and high quantum efficiency.

[0066] Quantum dots can have any suitable geometric shapes, such as rods, disks, prolate spheroids, and crystalline, polycrystalline, or amorphous nanoparticles, which can convert light at a preferred wavelength or range of wavelengths, absorb light at a selected wavelength, and / or convert energy in one form into another.

[0067] Examples of quantum dot semiconductor materials include, for example, Group II-VI, Group III-V, and Group IV-VI semiconductor materials. Suitable quantum dot materials include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, GaAs, GaP, GaAs, GaSb, HgS, HgSe, HgTe, InAs, InP, InSb, AlAs, AlP, and AlSb. Other examples of suitable quantum dot materials include InGaP, ZnSeTe, ZnCdS, ZnCdSe, and CdSeS. Multicore structures are also possible. An example of a multicore quantum dot configuration includes a quantum dot having a semiconductor core material, a thin metal layer to protect the core from oxidation and facilitate lattice matching, and a shell to enhance luminescence properties. The core and shell layers can be formed from the same material, for example, from any of the listed semiconductor materials. The metal layer may contain Zn or Cd. The core of a quantum dot may include graded compositions configured to distribute lattice mismatches that typically occur at the core-shell interface over longer distances in order to improve the performance and / or reliability of the quantum dot. For example, a quantum dot may include multiple shells for the purpose of distributing core-shell lattice mismatches and / or controlling exciton confinement and / or electron hole distribution and / or adding layers to improve the environment.

[0068] Quantum dots can have diameters of, for example, 1 nm to 10 nm, 1 nm to 8 nm, 1 nm to 6 nm, 1 nm to 5 nm, or 2 nm to 4 nm.

[0069] Multiple quantum dots can have polydispersity (PDI) values ​​less than 0.8 PDI, e.g., less than 0.7 PDI, less than 0.6 PDI, less than 0.5 PDI, less than 0.4 PDI, or less than 0.3 PDI. Multiple quantum dots can have PDI values ​​of, for example, 0.1–0.8, 0.2–0.7, or 0.3–0.6. PDI can be determined using light scattering. For example, dynamic light scattering (DLS) is a commonly used method. Another method that can give more accurate results regarding the apparent size of quantum dots in the usage environment is size exclusion chromatography.

[0070] To maintain separation between quantum dots that minimize FRET, quantum dots may include an outer layer that can be continuous or discontinuous. The outer layer of a quantum dot may perform one or more additional functions, such as providing desired electronic properties and / or desired chemical properties. Quantum dots generally have an initial outer shell from which further shells can be deposited, and the surface of a quantum dot may contain ligands, such as organic molecules, that further modify how the quantum dot interacts with its environment. Reduction of undesirable non-radioactive energy transfer can be achieved by using a high-bandgap outer coating and / or by designing ligands to establish minimum spacing between quantum dots.

[0071] Quantum dot coatings can have an average thickness of, for example, 1 nm to 6 nm.

[0072] The external quantum dot layer may include a coating, which may consist of a single layer or multiple layers.

[0073] Quantum dot coatings may include wavelength-selective coatings. For example, a wavelength-selective coating can be configured to transmit light in the blue wavelength range and light in the red or green wavelength range.

[0074] Quantum dots may include a reactive coating. The reactive coating may include unreacted reactive functional groups that can co-react with complementary reactive functional groups.

[0075] For example, a semiconductor shell can be grown on a semiconductor core to protect and passivate the semiconductor core of a quantum dot. The semiconductor shell improves the core emission efficiency and stability. Multilayer structures are also possible. An example of a multilayer structure includes a first shell material grown on the core, followed by a second shell material to improve the emission properties. The shell may function to absorb light in a specific spectrum different from the emission spectrum from the quantum dot.

[0076] Quantum dots may contain multiple coatings for purposes such as core-shell lattice mismatch distribution, exciton confinement control, electron-hole distribution control, and / or improved environmental robustness.

[0077] The outer layer may include, for example, a metal oxide coating. Suitable metal oxide coatings according to the embodiment include ZnO, ZrO2, Nb2O3, Sb2O3, NiO, Cu2O, WO3, and SnO x This includes Cr2O3, V2O5, MoO3, ReO3, In2O3, BiVO4, and SrTiO3.

[0078] Quantum dots may also contain organic ligands, and / or organic ligands bound to the surface of the quantum dot semiconductor core or to the coating surrounding the quantum dot semiconductor core. The ligands can be bound to the quantum dot or directly to the coating on the outer surface of the quantum dot.

[0079] Quantum dots may contain ligands or combinations of ligands. Ligands or combinations of ligands can serve one or more purposes. For example, a ligand may minimize the aggregation of quantum dots, provide spacing between adjacent quantum dots, provide a protective outer surface, and / or provide a reactive functional group that can react with other components of the pixel.

[0080] The ligand can include linear or branched molecules with one end covalently bonded to the surface of the quantum dot.

[0081] A quantum dot may have a core / shell configuration in which the shell may be a metal oxide, metal sulfide, or metal phosphide, and may have one or more layers of organic ligands or hybrid organic ligands that coordinate non-covalently to the surface of the quantum dot shell.

[0082] Quantum dots may include an outer surface containing a spacing ligand. When assembled within a subpixel, the spacing ligand can be selected to maintain spacing between adjacent quantum dots that minimizes FRET. For example, the spacing ligand can maintain spacing between adjacent quantum dots of 1 nm to 10 nm, 2 nm to 8 nm, 3 nm to 7 nm, or 4 nm to 6 nm. The spacing ligand can be selected to maintain average separation between adjacent quantum dots greater than 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, or 8 nm.

[0083] The ligand may contain a reactive ligand. The reactive ligand may contain one or more chemically reactive functional groups. The reactive ligand may be bonded, for example covalently, to a quantum dot, another ligand bonded to the quantum dot, or to an external coating on the quantum dot.

[0084] The reactive ligand can be configured to react, for example, with the complementary functional group of another quantum dot, with the complementary functional group of a binder, and / or with the complementary functional group of a ligand bound to an organic or inorganic particle.

[0085] Reactive functional groups can be selected to react upon exposure to chemical radiation such as ultraviolet (UV) radiation, or radiation in the blue wavelength range.

[0086] Examples of chemicals that react upon exposure to chemical radiation include thiol / thiolene, thiol / thioline, and certain Michael acceptors such as (meth)acryloyl / (meth)acryloyl. Therefore, the reactive functional group can be selected from thiol, alkenyl, alkynyl, and (meth)acryloyl groups.

[0087] Reactive ligands can react with complementary functional groups when exposed to thermal radiation. Thermally activated curing chemistry includes thiol / epoxy and thiol / Michael acceptor chemistry.

[0088] Examples of reactive ligands include amino-terminated acrylates, carboxy-terminated acrylates, sulfhydryl-terminated acrylates, alkenyl-terminated acrylates, and thiol-terminated acrylates.

[0089] The ligand may contain one or more functional groups that can react with the quantum dot.

[0090] The non-reactive ligand may contain one or more functional groups that can covalently bond to the quantum dot, and the other end of the non-reactive ligand may contain one or more chemical moieties that cannot react with other components of the subpixel.

[0091] The reactive ligand may contain one or more functional groups that can covalently bond to the quantum dot, and the other end of the reactive ligand may contain one or more chemical moieties that can react with one or more other components of the subpixel.

[0092] The ligand can be configured to promote adhesion, for example, between adjacent quantum dots, between quantum dots and the sidewalls of subpixels, and / or between quantum dots within subpixels and organic and / or inorganic particles.

[0093] Examples of suitable adhesion promoters include organically functional alkoxysilanes.

[0094] The ligand can be configured to control the minimum distance between the subpixel sidewall and the quantum dot.

[0095] The subpixels provided in this disclosure may include high-density quantum dots. For example, a subpixel may include quantum dots of 10 to 50 volume%, 15 to 45 volume%, 20 to 40 volume%, or 25 to 35 volume%, where volume% is based on the total volume of the subpixel. A subpixel may also include quantum dots of more than 10 volume%, more than 15 volume%, more than 20 volume%, more than 25 volume%, more than 30 volume%, more than 35 volume%, more than 40 volume%, or more than 45 volume%, where volume% is based on the total volume of the subpixel.

[0096] Subpixels can include, for example, quantum dots with less than 50 volume%, less than 45 volume%, less than 40 volume%, less than 35 volume%, less than 30 volume%, less than 25 volume%, less than 20 volume%, or less than 15 volume%, where volume% is based on the total volume of the subpixels.

[0097] Multiple quantum dots within a subpixel can be packed randomly or into a regular lattice such as a cubic lattice, and the cubic lattice includes hexagonal systems including bcc and fcc packing geometric shapes, tetrahedral lattices, or hcp, in addition to simple cubes. While bcc and fcc structures can be considered as interpenetrating cases of simple cubes, these are referred to herein to include cases where the QDs are not all the same, particularly cases where the core-shell structure is the same but the ligand structures are different. For example, a subpixel may contain quantum dots having two or more different ligand structures, one ligand structure may be configured to interact with the subpixel wall, for example, and another ligand structure may be configured to optimize the quantum dot function, for example.

[0098] A subpixel can contain multiple quantum dots, each of which is identical. For example, similar quantum dots may contain the same semiconductor material and have the same external composition.

[0099] A subpixel can include a plurality of quantum dots in which at least some of the quantum dots are different from the others. In such embodiments, the plurality of quantum dots may have the same semiconductor material, the same average diameter, and different outer coatings. For example, a first plurality of quantum dots may include a ligand or coating containing a first reactive functional group, and a second plurality of quantum dots may include a ligand or coating containing a second reactive functional group. The first reactive functional group may be reactive with the second functional group.

[0100] Subpixels may include, for example, binders, organic particles, and / or other organic particles.

[0101] The binder can be selected to provide a matrix for holding the quantum dots.

[0102] The binder can be provided as a material that can be intercalated between multiple quantum dots.

[0103] The binder can be provided as particles, such as particles with an average diameter smaller than that of quantum dots.

[0104] The binder may include a thermosetting composition or a thermoplastic composition. The thermosetting binder may have a low initial viscosity to facilitate filling the subpixel cavities with the quantum dot-containing composition. After curing, the binder may have a high degradation temperature to facilitate the use of semiconductor processing methods to integrate the color converter with other components of the display.

[0105] Quantum dot-containing compositions can be deposited and cured under vacuum or inert atmosphere to minimize degradation of the quantum dots caused by exposure to atmospheric oxygen.

[0106] Subpixels may contain organic and / or inorganic particles.

[0107] Organic particles can function, for example, as spacers and / or binders. Organic binder particles may include, for example, reactive functional groups that can react with functional groups on quantum dots or other particles within subpixels.

[0108] Organic particles can be formed from any suitable organic material. Organic particles can be selected to withstand high temperatures. Suitable high-temperature polymers include tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene (ECTFE), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkanes (PFA), polybenzimidazole (PBI), polyamideimide (PAI), polyetherimide (PEI), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyphenylene sulfide (PPS), phthalonitrile, polysulfone (PSU), polyethersulfone (PES), polyphthalamide (PPA), PTFE high-temperature nylon, and any combination of the above.

[0109] The organic particles may include, for example, polyester systems derived from cinnamic acid derivatives such as cinnamic acid-based polyacrylates, p-hydroxycinnamic acid (4HCA), ferulic acid (MHCA), caffeic acid (DHCA), and 4-aminocinnamic acid (4ACA), or polyimide systems derived from cyclobutanetetracapoxylic acid dianhydride and aminocinnamic acid derivatives.

[0110] Organic particles can be selected to facilitate the ability of subpixels to withstand thermal stress. Examples of suitable elastomer polymers include polyethers, polybutadienes, fluoroelastomers, perfluoroelastomers, ethylene / acrylic copolymers, ethylene propylene dienterpolymers, nitriles, and polythiolamines, as well as any combination thereof.

[0111] Inorganic particles can be configured to enhance the absorption cross-section of quantum dots, thereby improving the wavelength conversion efficiency of the quantum dots. For example, the efficiency-enhancing inorganic particles may include silver or gold. The wavelength conversion efficiency-enhancing particles may include solid silver or gold particles, or solid organic or inorganic particles having a silver or gold coating.

[0112] Particles that reflect incident radiation, such as blue light, can also reduce the transmission of incident light through a subpixel by increasing the internal reflection of incident radiation within the subpixel.

[0113] Subpixels may include an organic matrix material in which multiple quantum dots are embedded. The matrix material may include a crosslinkable material such as a thermosetting material. The matrix material may initially have low viscosity and may be curable when exposed to thermal energy or chemical rays such as ultraviolet light. The matrix material may include compounds that can chemically react with quantum dots, spacer particles, other components of the subpixel, and / or reactive ligands on the subpixel sidewalls.

[0114] It may be desirable for the matrix material to be stable for subsequent processing, including semiconductor processing conditions.

[0115] Subpixels can be configured to transmit radiation. For example, a color-converting subpixel can emit light in the blue wavelength range. A non-color-converting subpixel can be configured to transmit blue light and may include, for example, a material that is transparent to radiation in the blue wavelength range of 405 nm to 475 nm. A blue-transmitting subpixel may include silicon dioxide, such as silicon dioxide particles or a silicon dioxide thin film. The particles can be configured to produce emission patterns similar to those of color-converting subpixels and similar transmission patterns.

[0116] The conversion efficiency of subpixels can depend on the conversion efficiency of the quantum dot and geometric factors.

[0117] For example, the conversion efficiency can be determined by (1) the geometric pattern of the incident excitation radiation, (2) the loss at the entrance interface to the subpixel, including absorption, reflection, and entrance geometry, (3) the absorption and scattering of excitation radiation by the subpixel sidewalls and bulk matrix material, (4) the absorption cross-section of the quantum dot at the excitation wavelength, (5) the efficiency of the quantum dot for non-radiative processes, (6) the emission pattern of the quantum dot, which may depend on the shape and composition of the quantum dot, for example, (7) the energy difference between the excitation wavelength and the emission wavelength, (8) the recirculation of light within the subpixel, including the effect of coating on any edge of the subpixel and reabsorption by the quantum dot, and (9) the emission distribution from the exit of the subpixel, which is coincidentally one of the most important factors.

[0118] The conversion efficiency of quantum dots can depend on factors such as local heating, heat conduction, heat dissipation, material absorption, bleaching of quantum dots, and / or the creation and / or activation of defects within the quantum dots.

[0119] Multiple subpixels can have any preferred configuration. For example, multiple subpixels can be configured as a square matrix, a triangular matrix, a hexagonal matrix, or other regular matrix pattern.

[0120] A particular subpixel in a group of subpixels may have different dimensions, including different heights and / or widths, relative to other subpixels in the group. Different subpixel dimensions can be used to provide subpixels with different intensities or saturations.

[0121] Multiple subpixels can be composed of, for example, regular arrays, regular patterns, or irregular patterns.

[0122] Multiple subpixels can contain one or more groups of subpixels, each of which emits or transmits radiation at a different wavelength.

[0123] Multiple subpixels may include, for example, a group of subpixels that can provide radiation in the blue wavelength range, a group of subpixels that can provide radiation in the green wavelength range, and a group of subpixels that can provide radiation in the red wavelength range.

[0124] A group of subpixels capable of providing radiation in the red and green wavelength ranges may include multiple quantum dots capable of converting incident radiation in the blue wavelength range. Subpixels capable of providing radiation in the blue wavelength range may be transparent to blue radiation.

[0125] Multiple subpixels may include, for example, a group of subpixels containing multiple quantum dots that can emit radiation in the wavelength range of 515 nm to 565 nm when irradiated with blue light in the wavelength range of 405 nm to 475 nm.

[0126] Multiple subpixels may include, for example, a group of subpixels containing multiple quantum dots that can emit radiation in the wavelength range of 595 nm to 635 nm when irradiated with blue light in the wavelength range of 405 nm to 475 nm.

[0127] Multiple subpixels can include, for example, a group of subpixels containing multiple quantum dots that, when irradiated with blue light in the wavelength range of 405 nm to 475 nm, emit radiation in the wavelength range of 450 nm to 475 nm, with the 2σ point at the longer wavelength tail of the excitation wavelength being less than the emission wavelength.

[0128] Multiple subpixels may include, for example, a group of subpixels containing multiple quantum dots that can emit radiation in the wavelength range of 650 nm to 750 nm when irradiated with blue light in the wavelength range of 405 nm to 475 nm.

[0129] Multiple subpixels may include, for example, a group of subpixels containing multiple quantum dots that can emit radiation in the wavelength range of 650 nm to 750 nm when irradiated with blue light in the wavelength range of 470 nm to 620 nm.

[0130] Multiple subpixels may include, for example, a group of subpixels containing multiple quantum dots capable of transmitting light in the blue wavelength range of 405 nm to 475 nm.

[0131] For example, a subpixel may include a first group of subpixels, each subpixel of which includes a first group of quantum dots that can emit light at wavelengths in the green wavelength range of 515 nm to 565 nm when irradiated with blue light in the wavelength range of 405 nm to 475 nm; a second group of subpixels, each subpixel of which includes a second group of quantum dots that can emit light at wavelengths in the red wavelength range of 595 nm to 635 nm when irradiated with blue light in the wavelength range of 405 nm to 475 nm; and a third group of subpixels, each subpixel of which includes a third group of quantum dots that can convert ultraviolet light in the wavelength range of 400 nm to 425 nm into blue wavelength light in the 450 nm to 475 nm range.

[0132] Each group of subpixels can be independently composed of an array that is the same as or different from another array of subpixels.

[0133] Each group of subpixels in a multi-subpixel array can be configured in any suitable tile arrangement that is appropriate for providing a display. To provide a full-color display, arrays of subpixels can be arranged alternately.

[0134] Certain subpixels within the multiple subpixels that form a color converter may not contain quantum dots. Subpixels without quantum dots are intended to transmit light, such as light in the blue wavelength range, without converting incident radiation to another wavelength. Such subpixels can be filled with organic materials that are transparent to light in the blue wavelength range, for example, with transmittances exceeding 90%, 95%, or 99%.

[0135] A color converter can include, for example, 10 subpixels to 1,000,000 subpixels, for example, 100 subpixels to 750,000 subpixels, 1,000 subpixels to 500,000 subpixels, or 10,000 subpixels to 100,000 subpixels. A color converter can include, for example, more than 10 subpixels, more than 1,000 subpixels, more than 10,000 subpixels, more than 100,000 subpixels, more than 500,000 subpixels, or more than 1,000,000 subpixels. A color converter can include, for example, less than 2,000,000 subpixels, less than 1,000,000 subpixels, less than 500,000 subpixels, less than 100,000 subpixels, less than 1,000 subpixels, or less than 100 subpixels.

[0136] The color converter can have PPI (pixels per linear inch), for example, 100 PPI to 50,000 PPI, 1,000 PPI to 50,000 PPI, 5,000 PPI to 50,000 PPI, or 10,000 PPI to 50,000 PPI.

[0137] The color converter may have a PPI of, for example, 100 PPI to 5,000 PPI, 200 PPI to 5,000 PPI, or 500 PPI to 5,000 PPI.

[0138] A color converter having a thickness of less than 10 μm and a PPI of more than 10,000 is provided by this disclosure.

[0139] To achieve this, the color converter is preferably a single-pass device that minimizes the transmission of blue light to colored subpixels. For example, for red and green subpixels illuminated with blue light, it is desirable that the subpixels do not contain wavelength-selective filters, that the amount of blue light transmitted through each subpixel is less than 5%, corresponding to a 95% color conversion purity (95 red photons divided by 95 red photons + 5 blue photons), and that the emission distribution is relatively narrow. A significant improvement in overall efficiency can be achieved by narrowing the emission angle. For example, a hemispherical emitter emits at slightly over 6 sr. An emission cone with an angle containing 66° corresponds to 1 sr.

[0140] To facilitate the integration of the color converter provided by this disclosure, it is desirable that the materials used can withstand semiconductor processing temperatures, such as temperatures exceeding 200°C.

[0141] However, as long as the subpixels contain organic materials such as coatings and / or ligands on the quantum dot and organic matrix material, the subpixels may not be able to withstand semiconductor processing temperatures. Nevertheless, organic materials that can withstand higher temperatures are desired.

[0142] A color converter may include a color conversion layer that contains multiple subpixels and one or more additional layers.

[0143] A color converter may include a substrate beneath the color conversion layer. The substrate may be a sacrificial layer used to manufacture the color conversion layer. The substrate may include a semiconductor substrate or an inorganic substrate such as a metal substrate.

[0144] A color converter may include a passivation layer on top of the color conversion layer. The passivation layer can serve to flatten the color conversion layer and / or protect it during subsequent processing steps.

[0145] A color converter may include wavelength-selective regions above and / or below the color conversion layer. These wavelength-selective regions may include, for example, Bragg reflectors. A lower wavelength-selective region may be configured to transmit blue light and reflect green or red light. A higher wavelength-selective region may be configured to transmit red or green light and reflect blue light.

[0146] An example of a color converter including a wavelength-selective layer is shown in Figure 2. The color converter shown in Figure 2 includes a transparent layer 201, a peeling layer 202, a first wavelength-selective region 203 beneath a color conversion layer 204 containing green subpixels 204a, red subpixels 204b, and blue subpixels 204c, a passivation layer or seal layer 205, and a second wavelength-selective region 206 above the passivation layer 205. The transparent layer 201 may include, for example, sapphire, and the peeling layer 202 may include, for example, GaN or SOI.

[0147] The first wavelength-selective region 203 can be configured, for example, to transmit blue light within a first wavelength range and reflect green and red light. The second wavelength-selective region 205 can be configured to reflect blue light within a first wavelength range and transmit green, red, and blue light within a second wavelength range. The color conversion layer and pixels can have a thickness of, for example, 0.5 μm to 2 μm.

[0148] The color conversion layer may include aluminum or other metals between individual subpixels.

[0149] The second wavelength-selective region can have different properties across different subpixels. For example, the lateral portion of the second wavelength-selective region above the green and red subpixels can be configured to reflect incident blue radiation and transmit green and red radiation emitted by quantum dot-containing subpixels. The lateral portion of the second wavelength-selective region above the blue subpixel can be configured to transmit incident blue radiation, or may not be present, and the region above the blue subpixel may be filled with a light-transmitting material such as SiO2.

[0150] The wavelength-selective region above the color conversion layer can be configured to reflect light at wavelengths less than 460 nm, for example.

[0151] The wavelength-selective region may include a Bragg reflector, which is manufactured using any suitable combination of materials such as SiO2, TiO2, hafnium oxide, tantalum oxide, and aluminum oxide.

[0152] The wavelength-selective region may include a surface configured to reduce the dispersion of light emitted and / or transmitted by the color conversion layer.

[0153] The color converter may include an on-top lens array containing multiple lenses. These multiple lenses can be aligned with each subpixel and configured to narrow the dispersion of radiation emitted from the pixels. A suitable example of a nanostructured surface includes a nanometer-thick metal layer configured to enhance surface plasmon-enhanced emission.

[0154] A color converter may include a dissociation layer beneath the color conversion layer. The dissociation layer can minimize the coupling of light transmitted from one subpixel to another. The dissociation layer may include, for example, silicon dioxide, inorganic oxides, ceramics, metal oxides, non-stoichiometric suboxides, silicones, sulfones, or other suitable organic materials.

[0155] Quantum dot-containing subpixels within an ultra-high-density color converter should preferably contain a high density of quantum dots.

[0156] Depositing quantum dot-containing materials into cavities using conventional inkjet methods is difficult due to the high material viscosity resulting from the high concentration of quantum dots and the possibility of them being trapped within the cavities. Inkjet deposition under vacuum can minimize air trapping, at least to some extent.

[0157] High-density quantum dots can be obtained by preparing an ink containing quantum dots, depositing the ink into subpixel cavities, and removing at least a portion of the matrix material from the cavities without removing the quantum dots. Removal of the matrix material can be achieved, for example, using a permeation method of gel deposition, as described in U.S. Patent Application No. 16 / 172,562, filed on October 26, 2018, which is incorporated in its entirety by reference, and is titled "Methods of Modifying the Composition of Material Layers".

[0158] High-density quantum dots can be obtained by filling subpixel cavities with quantum dots and then intercalating a binder into the cavities. The binder may intercalate across the entire subpixel free volume between quantum dots, or it may act as a capping layer and intercalate into the upper section of the subpixels.

[0159] High-density quantum dots can be obtained by filling subpixel cavities with quantum dots in combination with binder particles. The binder particles are dispersed within the subpixel cavities together with the quantum dots.

[0160] High-density quantum dots can be obtained by filling subpixel cavities with quantum dots containing reactive ligands.

[0161] The binder, whether in the form of an ink, intercalated binder, binder particles, or reactive ligand, can crosslink with the subpixels to fix the quantum dots. The binder reaction can be initiated, for example, using chemical rays such as ultraviolet light, or thermally, depending on the curing chemistry used.

[0162] Inks containing quantum dots can be deposited into subpixel cavities, for example, by using roller coating to push the ink into the cavities by rubbing the surface of the color conversion layer with an elastomer blade, or by squeegee coating. Vacuum can be used to facilitate the ability of high-viscosity quantum dot-containing inks to fill high-aspect-ratio cavities.

[0163] As free-flowing particles, quantum dots can be deposited within subpixels using a microfluidic deposition method in which subpixel cavities are filled through flow channels and then capped with a binder to fix the particles in place. Filling pixels with freely flowing quantum dots can minimize the Vol% of binder in the subpixel, thereby increasing the density of quantum dots within the subpixel.

[0164] A color converter can be manufactured, for example, by depositing an aluminum layer on a substrate to define multiple subpixels, depositing multiple first quantum dots on the first multiple subpixels, depositing multiple second quantum dots on the second multiple subpixels, and depositing a light-transmitting material on the third multiple subpixels to provide three color vertices of the color gamut that form the color converter.

[0165] The substrate may include an Al2O3 layer, a Si3N4 lift-off layer on top of the Al2O3 layer, and an SiO2 layer on top of the Si3N4 lift-off layer.

[0166] The aluminum layer can have a thickness of 1 μm to 3 μm.

[0167] Multiple cavities may have, for example, a depth of 1 μm to 3 μm, a width of 1 μm to 3 μm, and a pitch of 3 μm to 5 μm.

[0168] Depending on the context, the color converter may include additional layers such as a reflection layer, a passivation layer, and a subpixel crosstalk reduction layer.

[0169] To assemble the color converter on the LED array, the color converter can be separated from the substrate by activating the lift-off layer, aligning the separated color converters on the LED array, and then coupling them. [Examples]

[0170] Embodiments provided by this disclosure are further illustrated by reference to the following examples illustrating the methods, compositions, and devices provided by this disclosure. It will be apparent to those skilled in the art that many modifications to both materials and methods can be made without departing from the scope of this disclosure.

[0171] Example 1 Figures 3A to 3J show blue light transmitted through arrays of subpixels having different dimensions and different pitches. The subpixels shown in Figures 3A to 3E have a diameter of 9.6 μm with a pitch of 12.5 μm (Figure 3A), a diameter of 3.6 μm with a pitch of 6 μm (Figure 3B), a diameter of 1.4 μm with a pitch of 3.3 μm (Figure 3C), a diameter of 1.4 μm with a pitch of 2.8 μm (Figure 3D), and a diameter of 1.4 μm with a pitch of 2.3 μm (Figure 3E).

[0172] Figures 3F to 3J show the corresponding subpixel arrays at a magnification of 200x.

[0173] Example 2 Figure 4 shows a subpixel window with a diameter of 1.4 μm and a pitch of 2.8 μm at a magnification of 500x.

[0174] Example 3 Figures 5A to 5C show blue, green, and red subpixels, respectively. The subpixels have a diameter of 9.6 μm and a thickness of 2 μm. Figure 5A shows the transmission of blue light from the LED array below through the subpixel array. Figure 5B shows green emission from a quantum dot irradiated with blue LED light. The quantum conversion efficiency from blue light to green light was 74%, and the blue light leakage was 12%. Figure 5C shows red emission from a quantum dot irradiated with blue LED light. The quantum conversion efficiency from blue light to red light was 57%, and the blue light leakage was 21%.

[0175] Green and red quantum dot-containing subpixels were prepared by pressing quantum dot-containing ink into wells.

[0176] Example 4 Figures 6A–6C show arrays of subpixels with a diameter of 2.8 μm (Figures 6A–6B) and subpixels with a diameter of 3.3 μm and a depth of 2 μm (Figure 6C). The magnifications are 200x and 500x (inset).

[0177] Example 5 Figure 7 shows an example of a color conversion layer with subpixel cavities. The structure includes an Al2O3 substrate 701, a 0.1 μm thick Si3N4 lift-off layer 702, a 500 nm thick SiO2 layer 703, a 2 μm thick layer 704 containing subpixels 705 separated by aluminum 706, and a 0.2 μm thick layer of SiO2. The subpixels 795 are filled with a quantum dot-containing composition and are 0.7 μm wide with a pitch of 1.3 μm.

[0178] Example 6 Figures 8A to 8F illustrate examples of steps used to manufacture a color converter. Figure 8A shows details of a substrate 801, including an Al2O3 wafer 802, a 0.1 μm thick layer of Si3N4 803, and a 0.5 μm thick layer of SiO2 804. In Figure 8B, an aluminum layer 805 is deposited on the substrate 801. A resist 806 is selectively deposited on the aluminum layer 805 and a chromium etch mask 807. Figure 8C shows the post-etched structure for defining subpixels 808. As shown in Figure 8D, specific subpixels are filled with a red light-emitting quantum dot composition 809. The red subpixels are then coated with a protective layer 810, such as SiO2, as shown in Figure 8E, and a green light-emitting quantum dot composition 811 is deposited on selected subpixels, as shown in Figure 8F. Blue light-transmitting subpixels 812 can be filled with a transparent material, and the color conversion layer is coated with a passivation layer (not shown).

[0179] The present invention may also take the embodiments described in the following clauses 1 to 30, but is not limited thereto. [Clause 1] A color converter for ultra-high density light-emitting diode arrays, circuit board and It includes a color conversion layer, and the color conversion layer is Includes a first group of subpixels on the substrate, The first group of subpixels includes the first set of quantum dots, The first set of subpixels emit light within a first wavelength range, Each subpixel operates independently. 30 μm 3 Volumes less than, A thickness of 1 μm to 3 μm, Pitch less than 5 μm, A color converter containing quantum dot density of 10% to 50% by volume, where the volume percentage is based on the total volume of quantum dots minus any ligand or other intervening material, divided by the total volume of subpixels. [Clause 2] A color converter as described in Clause 1, wherein each subpixel features an aspect ratio (height:width) of 2:1 to 10:1. [Clause 3] The color converter described in Clause 1 further includes a plurality of additional subpixels, one of which constitutes a colored pixel, and the plurality of additional subpixels are configured to transmit light within an additional wavelength range. [Clause 4] The color converter described in Clause 3, wherein one of the additional subpixels is configured to pass a pump wavelength through which the additional subpixels are provided, without containing quantum dot color conversion material. [Clause 5] The color converter according to Clause 1, wherein light within a first wavelength range, light within a second wavelength range, and light within a third wavelength range define three color vertices of the color gamut that characterize the color converter. [Clause 6] The color converter described in Clause 1, wherein the color conversion layer includes multiple pixels, each of which includes 1 to 5 subpixels. [Clause 7] A color converter as described in Clause 1, wherein the color conversion layer is characterized by 100 to 50,000 PPI. [Clause 8] The color converter according to Clause 1, wherein each subpixel of the first group of pixels and each pixel of the second group of pixels features an emission cone of less than 66°. [Clause 9] The color converter described in Clause 1, wherein each subpixel contains multiple transformation enhancement particles. [Clause 10] Each subpixel comprises a color converter according to Clause 1, including a binder. [Clause 11] A color converter according to Clause 1, wherein multiple quantum dots contain spaced ligands. [Article 12] A color converter according to Clause 1, wherein multiple quantum dots contain a reactive ligand. [Clause 13] The color converter according to Clause 12, wherein the reactive ligand is configured to chemically react with a binder, particles, sidewalls, complementary reactive ligands, and / or ligands and / or coatings of quantum dots. [Clause 14] The color converter described in Clause 1, wherein each of the first group of subpixels and the second group of subpixels exhibits a color conversion efficiency of more than 70% when irradiated with light in the wavelength range of 405 nm to 475 nm, and the color purity is more than 90%, corresponding to less than 10% transmission of pump light through the subpixels. [Article 15] The color converter described in Clause 1, wherein when irradiated with blue light in the wavelength range of 405 nm to 475 nm, a first group of subpixels can emit light in the green wavelength range of 515 nm to 565 nm, and a second group of subpixels can emit light in the red wavelength range of 565 nm to 650 nm. [Clause 16] The color converter described in Clause 1, wherein a first group of subpixels and a second group of subpixels are arranged alternately. [Article 17] The color converter according to Clause 1, further comprising a passivation layer below and / or above the color conversion layer. [Clause 18] The color converter according to Clause 1, further comprising a selective wavelength reflective layer below and / or above the color conversion layer. [Article 19] The color converter described in Clause 1, further comprising an optical dissociation layer beneath the color conversion layer. [Clause 20] The color converter according to Clause 15, further comprising a structuring layer on top of the color conversion layer, wherein the structuring layer is configured to focus the light emitted by a first group and a second group of subpixels. [Article 21] It is an optical display, A light-emitting diode array and An optical display comprising a color converter as described in Clause 1, which is located on and optically coupled to an array of light-emitting diodes. [Article 22] The optical display according to Clause 21, comprising a circuit layer located beneath and electrically interconnected to the light-emitting diode array. [Article 23] Electronic devices including optical displays as described in Article 21. [Article 24] A method for creating a color conversion layer, Depositing an aluminum layer on a substrate to define multiple cavities, A method of depositing a first color conversion material within a first portion of a plurality of cavities, wherein the first color conversion material includes a first plurality of quantum dots. The method involves depositing a second color conversion material within a second portion of a plurality of cavities, wherein the second color conversion material includes a second plurality of quantum dots. Each of the multiple cavities is 30 μm 3 Volumes less than, A thickness of 1 μm to 3 μm, Pitch less than 5 μm, A method that includes the density of quantum dots within a volume, ranging from 10% to 50% by volume, where the volume percentage is based on the total volume of subpixels. [Article 25] By depositing a color-transparent material in the third portion of multiple cavities, The method according to clause 24, further comprising providing three color vertices of the color gamut that characterize the color converter. [Article 26] The method according to clause 24, further comprising depositing a second array of color-converting materials and then initiating a polymerization reaction. [Article 27] The method according to Clause 24, wherein the deposition of the first color conversion array is carried out by gel permeation. [Article 28] The method according to Clause 24, wherein deposition includes coating an ink containing multiple quantum dots into a cavity. [Article 29] The method according to Clause 24, wherein the deposition includes depositing a free-flowing composition containing quantum dots into a cavity. [Clause 30] A color converter manufactured by the method described in Clause 24.

[0180] Finally, it should be noted that alternative methods exist for carrying out the embodiments disclosed herein. Therefore, these embodiments should be considered illustrative and not restrictive. Furthermore, the claims should not be limited to the details given herein, but rather the entire scope and its equivalents.

Claims

1. A color converter for ultra-high density light-emitting diode arrays, circuit board and The substrate includes a color conversion layer, the color conversion layer comprising an aluminum layer containing a first group of subpixels, Each subpixel of the first group of the subpixels includes a first plurality of quantum dots inside a cavity defined in the aluminum layer, The first group of subpixels emits light within a first wavelength range. Each subpixel operates independently. 30 μm ３ Volumes less than, Having a depth of 1 μm to 3 μm, The adjacent subpixels have a pitch of less than 5 μm. The density of the first plurality of quantum dots within the aforementioned volume is 10% to 50% by volume, and the volume percentage is based on the total volume of the quantum dots minus any ligand or other intervening material, divided by the total volume of the subpixels. A color converter in which each subpixel has an aspect ratio (depth:width) between 2:1 and 10:

1.

2. A second group of subpixels, wherein the second group of subpixels is configured to transmit light within a second wavelength range, The color converter according to claim 1, further comprising a third group of subpixels, wherein the third group of subpixels is configured to transmit light within a third wavelength range.

3. The color converter according to claim 2, wherein the second group of subpixels does not contain a quantum dot color conversion material and is configured to pass a pump wavelength.

4. The color converter according to claim 2, wherein the light in the first wavelength range, the light in the second wavelength range, and the light in the third wavelength range define three color vertices of the color gamut that characterizes the color converter.

5. The color converter according to claim 1, wherein the color conversion layer includes a plurality of pixels, and each of the plurality of pixels includes 1 to 5 subpixels.

6. The color converter according to claim 1, wherein the color conversion layer is characterized by 100 to 50,000 PPI.

7. The color converter according to claim 1, wherein at least a portion of the subpixels include color conversion efficiency improving particles, and the color conversion efficiency improving particles include silver particles, gold particles, or organic or inorganic particles having a silver or gold coating.

8. The color converter according to claim 1, wherein each subpixel contains a binder.

9. The color converter according to claim 1, wherein the first plurality of quantum dots include spacing ligands.

10. The color converter according to claim 1, wherein the first plurality of quantum dots contain a reactive ligand.

11. The color converter according to claim 10, wherein the reactive ligand is configured to chemically react with a binder, particles, sidewalls, complementary reactive ligands, and / or ligands and / or coatings of quantum dots.

12. The color converter according to claim 1, wherein each subpixel of the first group of the subpixels exhibits a color conversion efficiency of more than 70% when irradiated with light in the wavelength range of 405 nm to 475 nm, and has a color purity of more than 90%, corresponding to less than 10% transmission of pump light through the subpixels.

13. The color converter according to claim 1, wherein when irradiated with blue light in the wavelength range of 405 nm to 475 nm, the first group of subpixels can emit light in the green wavelength range of 515 nm to 565 nm or the red wavelength range of 565 nm to 650 nm.

14. The color converter according to claim 2, wherein the first group of subpixels, the second group of subpixels, and the third group of subpixels are arranged alternately.

15. The color converter according to claim 1, further comprising a passivation layer below and / or above the color conversion layer.

16. The color converter according to claim 1, further comprising a selective wavelength reflection layer below and / or above the color conversion layer.

17. The color converter according to claim 13, further comprising a plurality of lenses on the color conversion layer.

18. It is an optical display, A light-emitting diode array and An optical display comprising a color converter according to claim 1, which is located on and optically coupled to the light-emitting diode array.

19. The optical display according to claim 18, further comprising a circuit layer located beneath the light-emitting diode array and electrically interconnected with the light-emitting diode array.

20. An electronic device comprising an optical display as described in claim 18.

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