Ultra-high density quantum dot color converter

Abstract

A quantum dot-based color converter with high-density sub-pixels is disclosed. The sub-pixels have a high density of quantum dots, which can provide high conversion efficiency in a small sub-pixel aspect ratio and a small volume. The color converter can be used in optical displays.

Description

Technical Field

[0001] The present disclosure relates to a quantum dot color converter with high density pixels. The pixels have a high density of quantum dots. The color converter can be used in optical displays. Background Art

[0002] Pixel arrays containing quantum dots illuminated with LEDs are widely used in displays. Reducing the size of pixel arrays containing quantum dots used in applications such as integrated contact lens displays presents unique challenges. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The drawings described herein are for illustration purposes only. The drawings are not intended to limit the scope of the present disclosure.

[0004] Figure 1 Examples of green, red, and blue sub-pixels provided by the present disclosure are shown.

[0005] Figure 2 Examples of green, red, and blue sub-pixels are shown in conjunction with upper and lower Bragg reflectors provided in the present disclosure.

[0006] FIG. 3A to FIG. 3J Blue light is shown being transmitted through an array of sub-pixels having different diameters and different pitches.

[0007] Figure 4 Blue light is shown transmitted through an array of sub-pixels with a diameter of 1.4 μm and a pitch of 2.8 μm.

[0008] Figure 5A Blue light is shown transmitted through an array of sub-pixels with a diameter of 9.6 μm and a pitch of 12.5 μm.

[0009] Figure 5B Green light is shown emitted by a subpixel array containing quantum dots with a diameter of 9.6 μm, a pitch of 12.5 μm, and a thickness (depth) of 2 μm. The green quantum dot array can be pumped by the blue subpixel array below.

[0010] Figure 5C The red light emitted by a sub-pixel array containing quantum dots with a diameter of 9.6 μm, a pitch of 12.5 μm, and a thickness (depth) of 2 μm is shown. The red quantum dot array is pumped by the blue sub-pixel array below.

[0011] Fig. 6A The blue light transmitted by a blue sub-pixel array having a diameter of 1.4 μm, a pitch of 2.8 μm, and a thickness (depth) of 2 μm is shown.

[0012] Figure 6BGreen light is shown emitted by a sub-pixel array containing green quantum dots with a diameter of 1.4 μm, a pitch of 2.8 μm, and a thickness (depth) of 2 μm.

[0013] Figure 6C Green light is shown emitted by a sub-pixel array containing red quantum dots with a diameter of 1.4 μm, a pitch of 2.8 μm, and a thickness (depth) of 2 μm.

[0014] Figure 7 An example of a color conversion layer provided by the present disclosure is shown.

[0015] FIG. 8A to FIG. 8F An example of steps for making a quantum dot color converter provided by the present disclosure is shown.

[0016] Fig. 9 An array of sub-pixels and a pixel comprising sub-pixels of different colors are shown. DETAILED DESCRIPTION

[0017] Although the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variations, inter-individual differences, and / or daily variations found in their respective testing measurements.

[0018] In addition, it should be understood that any numerical range recited herein is intended to include all subranges subsumed therein. For example, a range of "1 to 10" is intended to include all subranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0019] A "color converter" refers to a structure configured to convert the wavelength of incident radiation (such as light from an array of blue-emitting light emitting diodes (LEDs)) into emitted light in one or more different wavelength ranges (such as light in the green and red wavelength ranges). The color converter includes a plurality of pixels and may include a plurality of layers, including a color conversion layer including a plurality of sub-pixels and one or more other layers such as a passivation layer, a reflective layer, a crosstalk minimization layer, and / or a focusing layer.

[0020] A "color conversion element" refers to a volume that includes a plurality of quantum dots. For example, a color conversion element may include a plurality of quantum dots that are capable of converting blue light into red and / or green light.

[0021] The “red wavelength range” refers to a wavelength range of 565 nm to 650 nm.

[0022] The “far-red wavelength range” refers to a wavelength range of 650 nm to 750 nm.

[0023] The "green wavelength range" refers to a wavelength range of 515 nm to 565 nm.

[0024] The “blue wavelength range” refers to a wavelength range of 405 nm to 475 nm.

[0025] "Sub-pixel" refers to an individually addressable element in a display device. A sub-pixel may include a color conversion element and optionally include one or more material layers below the color conversion element and / or one or more material layers above the color conversion element. The one or more material layers below and / or above may provide one or more functions. For example, the lower layer may be used as a substrate, a wavelength selective filter, or a layer designed to minimize crosstalk between a pixel and a sub-pixel. The upper material layer may be used as, for example, a passivation layer, a wavelength selective filter, or a lens.

[0026] A "pixel" refers to a group of sub-pixels that are repeated on a display. For example, a pixel may include 2 to 6 (such as 2, 3, 4, 5, or 6) sub-pixels. A pixel may include, for example, a red sub-pixel, a green sub-pixel, and a blue sub-pixel. Other color combinations are also possible.

[0027] Sub-pixels containing quantum dots are widely used in displays.

[0028] For some applications, it may be desirable to have an ultra-high density quantum dot full color converter with a thickness of less than 2 μm and a sub-pixel pitch of less than 2 μm. Fabricating quantum dot sub-pixels of this size with high overall conversion efficiency and integrating ultra-high density quantum dot color converters into rugged miniaturized optical displays requires the use of specialized materials and processes.

[0029] An optical display may include a quantum dot color converter above an LED array. The color converter may include an array of sub-pixels. Certain sub-pixels may include quantum dots capable of converting incident light in a first wavelength range into emitted light in a second wavelength range. For example, in the case of a display, incident blue light may be converted into emitted light in a red wavelength range, other sub-pixels may include quantum dots capable of emitting light in a green wavelength range when illuminated by light in a blue wavelength range, and other sub-pixels may be transparent to light in a blue wavelength range. Each sub-pixel may be aligned with a corresponding blue light emitting LED in the LED array.

[0030] Ultra-high density optical displays, such as those with a sub-pixel pitch of less than 5 μm, can be used in portable electronic devices and contact lens arrays. For example, contact lenses incorporating optical displays are described in U.S. Patent Application Publication No. 2018 / 0149884. Ultra-high density optical displays, especially those for contact lenses, present unique design requirements. It is well known that a display "looks sharp" (Snellen 20 / 20) when the pixel density exceeds one pixel per arc second. Snellen 20 / 20 is not "perfect" human vision, but is close to the average level of a 60-year-old adult. Young adults without visual impairment have vision between 20 / 16 and 20 / 12. Snellen 20 / 12 corresponds to 100 pixels / degree, further limiting the pixel size. Since angular resolution is defined in pixels / degree, the closer the display is to the eye, the higher the display pixel PPI (pixels per linear inch) must be to achieve the desired Snellen angular resolution. QLED TVs have a pixel pitch of about 150 μm to accommodate a viewing distance of about 2 m, and the thickness of the color conversion film containing quantum dots is about 15 μm. Mobile phones have a pixel pitch of about 55 μm to accommodate a viewing distance of about 0.3 m. Head-mounted displays can have a pixel pitch of about 9 μm for viewing from a distance of about 0.04 m. Displays on contact lenses about 25 mm from the retina should have a pixel pitch of about 1.8 μm to meet the 60 pixels / degree indicator for 20 / 20 vision with 3x magnification from the contact lens display to the retinal image over a field of view of about 5 degrees. Fig. 9 An example of a pixel having four sub-pixels is shown.

[0031] Increased PPI and pixel pitch affect the requirements for the color conversion layer. Color conversion efficiency is defined as the number of color conversion photons in the red, green or other wavelength range emitted from a particular color conversion sub-pixel divided by the number of pump photons (such as blue or ultraviolet photons) that impinge on the color conversion layer. The color conversion efficiency depends on the distance between the quantum dots and the material isolating the quantum dots. A small number of pump photons may leave the display to reduce the color purity. Color conversion purity is a measure of the purity of the light leaving a particular color conversion sub-pixel and is defined as the number of color conversion photons divided by the total number of photons (including color conversion photons and pump photons) leaving the particular color conversion sub-pixel. For example, for a red conversion sub-pixel, color conversion purity is defined as the number of red photons leaving the red sub-pixel divided by the sum of the number of red photons and the number of pump photons (such as blue photons) leaving the same red sub-pixel. It is desirable to increase both color conversion efficiency and color conversion purity to 100%, and both metrics become more difficult to increase as pixel size and thickness decrease. Color conversion purity is a strong function of the optical properties of the specific quantum dots within the color conversion film and the quantum dot density. As the pixel width decreases from QLED TV displays with subpixel sizes of approximately 75 μm to pixel widths of less than about 2 μm for ultra-high density contact lens displays, it becomes impractical to maintain subpixels containing quantum dots that are 15 μm thick due to the challenges of manufacturing subpixels containing quantum dots with high aspect ratios. In addition, in certain applications such as contact lens displays, it is desirable for the display to be as thin as possible. In order to meet the goals of practical manufacturing and thin displays, a subpixel height of 2 μm or less may be desired. Then, in order to maintain an acceptable color conversion efficiency greater than about 50% and an acceptable color conversion purity greater than about 80%, the density of quantum dots within high aspect ratio subpixels must be increased. However, the actual density of quantum dots is limited by the Forster resonance energy transfer between adjacent quantum dots, and in order to mitigate the effects of Forster resonance energy transfer (FRET), adjacent quantum dots require a uniform spacing of about 5 nm to about 10 nm. Energy transfer to other subpixel elements such as metal sidewalls can also reduce efficiency. The present disclosure provides a color converter having a total thickness of less than about 10 μm and having a color conversion layer including a plurality of sub-pixels having a pitch less than about 2 μm and a width less than about 2 μm.

[0032] Challenges in making ultra-high-density color converters include: providing coatings on the quantum dots that allow dense quantum dot packing and minimize FRET; developing structures and processes that can set RGB (red / green / blue) subpixels with a PPI greater than 10,000 on a pitch less than 5μm (about 3,900 PPI for a 6.4μm pitch and about 19,500 PPI for a 1.3μm pitch); and providing an accurate color gamut with acceptable dark levels and low crosstalk between subpixels.

[0033] The color converter provided by the present 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 optional additional layers (such as a reflective layer and a lens layer).

[0034] The color conversion layer may include a plurality of sub-pixels, at least some of the sub-pixels including a plurality of quantum dots.

[0035] The volume fraction of quantum dots within a pixel may be 10% to 70%, 10% to 50%, such as 10% to 40%, 10% to 30% or 10% to 20%.

[0036] The color conversion layer can have a thickness of, for example, less than 20 μm, less than 15 μm, less than 10 μm, or less than 5 μm.

[0037] The color conversion layer including a plurality of sub-pixels may have a thickness of, for example, 0.2 mm 2 Up to 10mm 2 area.

[0038] The color conversion layer may have a linear dimension of, for example, 0.2 mm to 1.5 mm.

[0039] An example of a color conversion layer is shown in Figure 1 Shown in. Figure 1 A silicon CMOS circuit 101 is shown interconnected with an upper LED array 102. A color conversion layer 103 is composed of a layer 104 including a plurality of sub-pixels, a passivation layer 105 below, and a passivation layer 106 above. Individual LEDs are aligned with individual sub-pixels. The pixel layer 104 includes green sub-pixels 104a and red sub-pixels 104b including a plurality of green quantum dots and a plurality of red quantum dots, respectively, and also includes a blue sub-pixel 104c configured to transmit light in the blue wavelength range emitted by the LED array 102. The thickness of the color conversion layer 103 may be, for example, 2 μm.

[0040] The 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. For optical displays, the incident light can be within the blue wavelength range, and multiple sub-pixels can be selected to provide an acceptable color gamut for the visual display. A four-color display designed to produce 100% REC2020 may include, for example, red, green, blue, and cyan sub-pixels. A four-color display designed to maintain night vision may add a deep red (DR) sub-pixel with a peak emission wavelength greater than about 720nm.

[0041] For certain applications, it may be desirable for the color converter provided by the present disclosure to exhibit the following properties: quantum conversion efficiency from 455 nm blue light to green or red light is greater than 80%, blue light leakage through the green and red sub-pixels is less than 2%, layer thickness is less than 2 μm, sub-pixel pitch is 3.3 μm or less, crosstalk or extinction ratio between adjacent sub-pixels may be less than 1000:1, and the color conversion layer is compatible with SiO2 sealant technology and other dielectric films configured to provide a hermetic seal within a useful time frame.

[0042] In some color conversion layers, blue light from the LED array may be transmitted through a blue transmissive sub-pixel. In some color converters, the LED may emit light, such as in a wavelength range of 400nm to 430nm, and the blue sub-pixel may include a plurality of quantum dots capable of absorbing light in the wavelength range of 400nm to 430nm and emitting light in a blue wavelength range (e.g., 450nm to 490nm).

[0043] In some color converters, the LED array may emit light in the near-ultraviolet wavelength range (eg, 300 nm to 400 nm) or other suitable wavelength range.

[0044] In certain color converters, an LED array may emit light in the near-infrared wavelength range (eg, 780 nm to 1700 nm) or other suitable wavelength range, and quantum dots may absorb and up-convert multiple low-energy photons into desired visible light wavelengths.

[0045] In certain color conversion layers, all or some of the plurality of sub-pixels may include quantum dots capable of emitting light in the red to near infrared wavelength range, such as 650 nm to 750 nm.Near infrared displays may be used for night vision applications.

[0046] The color conversion layer may include a plurality of pixels. For example, the color conversion layer may include 1,000 to 1,000,000, 5,000 to 50,000, or 10,000 to 100,000 pixels. The color conversion layer may include, for example, greater than 1,000, greater than 5,000, greater than 10,000, greater than 100,000, or greater than 1,000,000 pixels.

[0047] The color conversion layer may include pixels that emit a single color, or may include groups of sub-pixels, where each group of sub-pixels emits light in a different wavelength range. Any suitable number of groups of sub-pixels that emit light in different wavelength ranges may be used. An example of a pixel that includes four sub-pixels is shown in FIG. Fig. 9 As shown in , the sub-pixels emit light in the red, green, blue, and cyan wavelength ranges. Fig. 9Shown is an array of hexagonal sub-pixels 901. Pixel 902 includes a red sub-pixel 901a, a cyan sub-pixel 901b, a green sub-pixel 901c, and a blue sub-pixel 901d.

[0048] The plurality of sub-pixels may be configured to convert incident light in a first wavelength range into emitted light in one or more wavelength ranges. For example, the incident light may be in a blue wavelength range and the emitted light may be in red, green, deep red, and blue wavelength ranges.

[0049] Multiple sub-pixels can also be configured without any color conversion layer so that the incident pump wavelength is emitted directly from the sub-pixel. Fig. 9 , the blue sub-pixel may include blue light emitted by a blue pump LED, or may be the blue light emission of a sub-pixel including blue light emitting quantum dots.

[0050] The maximum in-plane dimension of a sub-pixel may be, for example, 1 μm to 4 μm, 1 μm to 3 μm, or 1 μm to 2 μm.

[0051] The maximum in-plane dimension of a sub-pixel may be, for example, less than 5 μm, less than 4 μm, less than 3 μm, less than 2 μm, or less than 1 μm.

[0052] The depth of the sub-pixel may be, for example, 0.5 μm to 4 μm, 0.5 μm to 3 μm, or 0.5 μm to 2 μm.

[0053] The height and width of the sub-pixel may be, for example, 0.5 μm to 3 μm and 0.5 μm to 3 μm, 1 μm to 3 μm and 1 μm to 3 μm, or 1 μm to 2 μm and 1 μm to 2 μm, respectively.

[0054] The depth of a sub-pixel may be equal to or greater than the maximum in-plane dimension.

[0055] The aspect ratio of the sub-pixel may be, 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.

[0056] The aspect ratio (height: width) of the sub-pixel may be, 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 aspect ratio (height: width) of the sub-pixel may be, 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.

[0057] The volume of a sub-pixel can be, for example, 0.1 μm 3 Up to 70μm3 , 1μm 3 Up to 64μm 3 , 3μm 3 Up to 40μm 3 , 6μm 3 Up to 50μm 3 , or 10μm 3 Up to 40μm 3 The volume of a sub-pixel can be, for example, less than 70 μm 3 , less than 60μm 3 , less than 50μm 3 , less than 40μm 3 , less than 30μm 3 , less than 20μm 3 , less than 10μm 3 , or less than 1μm 3 .

[0058] The aspect ratio (height:width) of the sub-pixel may be 10:1 to 2:1, 8:1 to 2:1, 6:1 to 2:1, or 4:1 to 2:1; the height of the sub-pixel may be 0.5 μm to 3 μm or 1 μm to 3 μm.

[0059] The aspect ratio (height:width) of the sub-pixel may be 10:1 to 2:1, 8:1 to 2:1, 6:1 to 2:1, or 4:1 to 2:1; the width of the sub-pixel may be 1 μm to 3 μm, or 1 μm to 2 μm.

[0060] The aspect ratio (height / width) of the sub-pixel may be 16:1 to 4:1, 12:1 to 4:1, 10:1 to 4:1, 8:1 to 4:1, or 6:1 to 4:1; the height of the sub-pixel may be 0.5 μm to 3 μm, or 1 μm to 3 μm.

[0061] The aspect ratio (height:width) of the sub-pixel may be 16:1 to 4:1, 12:1 to 4:1, 10:1 to 4:1, 8:1 to 4:1, or 6:1 to 4:1; the width of the sub-pixel may be 1 μm to 3 μm, or 1 μm to 2 μm.

[0062] By comparison, quantum dot LEDs with a 20μm pitch used in TV displays have an aspect ratio (height / width) of about 1:2.

[0063] The sub-pixels may have any suitable cross-sectional profile. For example, the sub-pixels may have a square cross-sectional profile, a hexagonal cross-sectional profile, or a circular cross-sectional profile.

[0064] The width of a sub-pixel may be, for example, 0.5 μm to 10 μm, and the area of ​​a sub-pixel may be, for example, 0.2 μm. 2 Up to 30μm2 .

[0065] The sub-pixels may be defined by materials such as inorganic materials or organic materials.

[0066] The materials defining the sub-pixels may be selected to not absorb 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.

[0067] Examples of suitable inorganic materials include semiconductors, metals, and metal alloys. For example, the material defining the sub-pixels may include aluminum.

[0068] Examples of suitable organic materials include polymers, polymer composites, thermally conductive polymer composites, or electrically conductive polymer composites.

[0069] A sub-pixel may include a cavity or well defined within a thin film, such as a cavity within an aluminum thin film.

[0070] Sub-pixels may include features deposited or built on a substrate, wherein the space between adjacent sub-pixels is filled with material. The sub-pixels may be defined by a cavity created by a subtractive process, including, for example, a chemical-based process (such as chemical etching), a physical-based process (such as ion milling), or a combination thereof (such as plasma etching). The sub-pixels may be defined by a cavity created by an additive process, including, for example, a chemical-based process (such as electrochemical plating), a physical-based process (such as physical vapor deposition, evaporation, or sputtering), or a combination thereof (such as atomic layer deposition, chemical vapor deposition, or laser-guided plating).

[0071] The plurality of sub-pixels may include a plurality of color conversion elements disposed on a common substrate. For example, the common substrate may be an aluminum layer. The color conversion element may be defined as a cavity or well within the aluminum substrate such that the sidewalls include aluminum. The bottom of the sub-pixel may include a light transmissive material such as a blue light transmissive material to allow illumination of the sub-pixel by a blue light emitting LED. The color conversion element may be defined by the material between the substrate and the color conversion element. The substrate and the separation material may be the same or different.

[0072] The sub-pixels may have vertical sidewalls or non-vertical sidewalls. The sidewalls may be configured to promote forward light scattering. The sidewalls may be configured to reflect light from the LEDs, and / or reflect light emitted by quantum dots within the sub-pixels.

[0073] The sidewalls of the subpixels can be configured to reflect, scatter and / or guide light to control the far-field emission pattern of light emitted / transmitted by the subpixels. For example, the subpixel sidewalls can be configured so that light is at the excitation wavelength of the quantum dots and / or can reflect or guide light emitted by the quantum dots. This can be achieved by coating the subpixel sidewalls with a material that has a different refractive index at the excitation wavelength and the emission wavelength.

[0074] The subpixels may be configured to convert incident light within a first wavelength range into light within a second wavelength range. Other subpixels may be configured to transmit light through the subpixels. Figure 1 As shown in FIG. 1 , sub-pixels 104a and 104b convert blue light into green light and red light, respectively, and pixel 104c transmits blue light.

[0075] The color conversion sub-pixel may include a plurality of quantum dots.The transmissive sub-pixel may include a material that does not absorb incident radiation.

[0076] The transmissive sub-pixel may include a material configured to modify the transmissive pattern to be similar to the emissive pattern of the color conversion sub-pixel.

[0077] Quantum dots are semiconductor materials with a size, composition, and structure in which their electrical and optical properties differ from those of the bulk due to quantum confinement effects. The fluorescence of quantum dots is produced by the excitation of valence electrons by light absorption, followed by emission at a lower energy wavelength when the excited electrons return to the ground state. Quantum confinement causes the energy difference between the valence band and the conduction band to vary depending on the size, composition, and structure of the quantum dot. For example, the larger the quantum dot, the lower the energy of its fluorescence spectrum. The photoluminescence emission wavelength of quantum dots can have a sharp emission spectrum and exhibit high quantum efficiency.

[0078] Quantum dots can have any suitable geometry, such as rods, disks, prolate spheroids, and crystalline, polycrystalline, or amorphous nanoparticles that can convert light of a suitable wavelength or range of wavelengths, absorb light of a selected wavelength, and / or convert one form of energy into another form of energy.

[0079] Examples of quantum dot semiconductor materials include, for example, II-VI, III-V, and 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. It may also be a multi-core structure. Examples of multi-core quantum dot configurations include quantum dots with semiconductor core materials, thin metal layers that protect the core from oxidation and promote lattice matching, and shells that enhance luminescence properties. The core layer and the shell layer may be formed of the same material, and may be formed of, for example, any semiconductor material listed. The metal layer may include Zn or Cd. The core of a quantum dot may include a graded composition configured to distribute the lattice mismatch that typically occurs at the core-shell interface over a greater distance to improve the performance and / or reliability of the quantum dot. For example, to distribute the core-shell lattice mismatch, and / or control exciton confinement and / or electron-hole distribution, a quantum dot may include multiple shells; and / or add layers to improve the environment.

[0080] The diameter of the quantum dot may be, for example, 1 nm to 10 nm, such as 1 nm to 8 nm, 1 nm to 6 nm, 1 nm to 5 nm, or 2 nm to 4 nm.

[0081] The polydispersity index (PDI) of multiple quantum dots can be less than 0.8, such as less than 0.7, less than 0.6, less than 0.5, less than 0.4, or less than 0.3. The PDI of multiple quantum dots can be, for example, 0.1 to 0.8, 0.2 to 0.7, or 0.3 to 0.6. The PDI can be determined using light scattering. For example, dynamic light scattering DLS is a common method. Another method that can give more accurate results about the apparent size of quantum dots in the use environment is size exclusion chromatography.

[0082] In order to maintain the separation between quantum dots to minimize FRET, quantum dots may include an outer layer that may be continuous or discontinuous. The outer layer of the quantum dot may play an additional one or more roles, such as providing desired electronic properties and / or providing desired chemical properties. Quantum dots typically have an initial shell on which more shells may be deposited, and the surface of the quantum dots may include ligands such as organic molecules, which further change the way the quantum dots interact with the environment. Using a high bandgap outer coating and / or by designing ligands to establish a minimum spacing between quantum dots, it is possible to achieve a reduction in undesirable non-radiative energy transfer.

[0083] The average thickness of the quantum dot coating can be, for example, 1 nm to 6 nm.

[0084] The outer quantum dot layer may include a coating, which may include a single layer or multiple layers.

[0085] The quantum dot coating may include a wavelength selective coating. For example, the wavelength selective coating may be configured to transmit light in the blue wavelength range and transmit light in the red or green wavelength range.

[0086] The quantum dots may include a reactive coating. The reactive coating may include unreacted reactive functional groups that are capable of co-reacting with complementary reactive functional groups.

[0087] 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 increases the core emission efficiency and stability. A multilayer structure is also possible. An example of a multilayer structure includes a first shell material grown on a core, followed by a second shell material, etc. to enhance the luminescent properties. The shell can act to absorb light of a specific spectrum that is different from the emission spectrum of the quantum dot.

[0088] Quantum dots may include multiple coatings to distribute the core-shell lattice mismatch, control exciton confinement, control electron-hole distribution, and / or improve environmental robustness.

[0089] The outer layer may include, for example, a metal oxide coating. Suitable metal oxide coatings according to embodiments include ZnO, ZrO2, Nb2O3, Sb2O3, NiO, Cu2O, WO3, SnO x , Cr2O3, V2O5, MoO3, ReO3, In2O3, BiVO4 and SrTiO3.

[0090] The quantum dots may also include organic ligands and / or organic ligands bound to the surface of the quantum dot semiconductor core or to a coating surrounding the quantum dot semiconductor core. The ligands may be bound directly to the quantum dots or to a coating on the outer surface of the quantum dots.

[0091] The quantum dots may include a ligand or a combination of ligands. The ligand or combination of ligands may be used for one or more purposes. For example, the ligand may minimize aggregation of the quantum dots, provide spacing between adjacent quantum dots, provide a protective outer surface, and / or provide reactive functional groups that can react with other components of the pixel.

[0092] The ligand may include a linear molecule or a branched molecule, one end of which is covalently bound to the surface of the quantum dot.

[0093] Quantum dots may have a core / shell configuration, where 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 non-covalently coordinated to the quantum dot shell surface.

[0094] The quantum dots may include an outer surface including a spacer ligand. The spacer ligand may be selected so that when assembled in a subpixel, the spacing between adjacent quantum dots minimizes FRET. For example, the spacer ligand may maintain a spacing of 1 nm to 10 nm, 2 nm to 8 nm, 3 nm to 7 nm, or 4 nm to 6 nm between adjacent quantum dots. The spacer ligand may be selected so that the average spacing maintained between adjacent quantum dots is greater than 2 nm, greater than 3 nm, greater than 4 nm, greater than 5 nm, greater than 6 nm, greater than 7 nm, or greater than 8 nm.

[0095] The ligand may include a reactive ligand. The reactive ligand may include one or more chemically reactive functional groups. The reactive ligand may be bound to (such as covalently bound to) the quantum dot, another ligand bound to the quantum dot, or an outer coating on the quantum dot.

[0096] The reactive ligand can be configured to react, for example, with a complementary functional group of another quantum dot, with a complementary functional group of a binder, and / or with a complementary functional group of a ligand associated with an organic or inorganic particle.

[0097] The reactive functional group may be selected to react upon exposure to actinic radiation, such as ultraviolet (UV) radiation or radiation in the blue wavelength range.

[0098] Examples of chemical species that react when exposed to actinic radiation include thiol / ene, thiol / alkyne and certain Michael acceptors such as (meth)acryloyl / (meth)acryloyl. Thus, the reactive functional group may be selected from thiol, alkenyl, alkynyl and (meth)acryloyl.

[0099] Upon exposure to thermal radiation, the reactive ligand can react with the complementary functional group. Heat activated cure chemistries include thiol / epoxy and thiol / Michael acceptor chemistries.

[0100] Examples of reactive ligands include amino-terminated acrylates, carboxyl-terminated acrylates, mercapto-terminated acrylates, alkenyl-terminated acrylates, and thiol-terminated acrylates.

[0101] The ligand may include one or more functional groups capable of reacting with the quantum dots.

[0102] The non-reactive ligand may include one or more functional groups capable of covalently binding to the quantum dot, and the other end of the non-reactive ligand may include one or more chemical moieties that are incapable of reacting with other components of the sub-pixel.

[0103] The reactive ligand may include one or more functional groups capable of covalently bonding to the quantum dot, and the other end of the reactive ligand may include one or more chemical moieties capable of reacting with one or more other components of the sub-pixel.

[0104] The ligands may be configured to promote adhesion, for example, between adjacent quantum dots, between quantum dots and subpixel sidewalls, and / or between quantum dots and organic and / or inorganic particles within a subpixel.

[0105] Examples of suitable adhesion promoters include organofunctional alkoxysilanes.

[0106] The ligands can be configured to control the minimum distance between the subpixel sidewalls and the quantum dots.

[0107] The sub-pixels provided by the present disclosure may include high-density quantum dots. For example, the sub-pixels may include 10 vol% to 50 vol%, 15 vol% to 45 vol%, 20 vol% to 40 vol%, or 25 vol% to 35 vol% quantum dots, where vol% is based on the total volume of the sub-pixel. The sub-pixels may include, for example, greater than 10 vol%, greater than 15 vol%, greater than 20 vol%, greater than 25 vol%, greater than 30 vol%, greater than 35 vol%, greater than 40 vol%, or greater than 45 vol% quantum dots, where vol% is based on the total volume of the sub-pixel.

[0108] A subpixel may include, for example, less than 50 vol%, less than 45 vol%, less than 40 vol%, less than 35 vol%, less than 30 vol%, less than 25 vol%, less than 20 vol%, or less than 15 vol% quantum dots, where the vol% is based on the total volume of the subpixel.

[0109] Multiple quantum dots within a subpixel can be randomly packed or packed in a regular lattice, such as a cubic lattice, including bcc and fcc packing geometries, tetrahedral lattices, or hexagonal systems including hcp in addition to simple cubic. Although bcc and fcc structures can be considered as interpenetrating cases of simple cubic, this article mentions that it includes cases where the QDs are not exactly the same, especially cases where the core-shell structure is the same but the ligand structure is different. For example, a subpixel may include quantum dots with two or more different ligand structures, where one ligand structure can be configured, for example, to interact with the subpixel wall, and another ligand structure can be configured, for example, to optimize the function of the quantum dot.

[0110] A sub-pixel may include a plurality of quantum dots, wherein each quantum dot in the plurality of quantum dots is identical. For example, similar quantum dots may include the same semiconductor material and may have the same external composition.

[0111] The subpixel may include a plurality of quantum dots, wherein at least some of the quantum dots are different from other quantum dots in the plurality of quantum dots. In such an embodiment, the plurality of quantum dots may have the same semiconductor material, have the same average diameter, and have different outer coatings. For example, a first plurality of quantum dots may include a ligand or coating comprising a first reactive functional group, and a second plurality of quantum dots may include a ligand or coating comprising a second reactive functional group. The first reactive functional group may react with the second functional group.

[0112] The sub-pixels may include, for example, a binder, organic particles, and / or inorganic particles.

[0113] The binder can be selected to provide a matrix that retains the quantum dots.

[0114] The binder may be provided as a material capable of being interposed between the plurality of quantum dots.

[0115] The binder may be provided as particles, such as microparticles having an average diameter that is smaller than the average diameter of the quantum dots.

[0116] The adhesive may include a thermosetting composition or a thermoplastic composition. The thermosetting adhesive may have a low initial viscosity to facilitate filling the subpixel cavity with a composition containing quantum dots. After curing, the adhesive may have a high degradation temperature to facilitate integration of the color converter with other components of the display using semiconductor processing methods.

[0117] The quantum dot-containing composition may be deposited and cured under vacuum or an inert atmosphere to minimize quantum dot degradation due to exposure to atmospheric oxygen.

[0118] The sub-pixels may include organic particles and / or inorganic particles.

[0119] The organic particles may function, for example, as spacers and / or binders. The organic binder particles may include, for example, reactive functional groups that are capable of reacting with functional groups on quantum dots or other particles within a sub-pixel.

[0120] The organic particles may be formed from any suitable organic material.

[0121] The organic particles may be selected to withstand high temperatures. Examples of suitable high temperature polymers include tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene (ECTFE), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (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 combinations of any of the foregoing.

[0122] The organic particles may include, for example, cinnamate-based polyacrylates, polyesters derived from cinnamate derivatives such as p-hydroxycinnamic acid (4HCA), ferulic acid (MHCA), caffeic acid (DHCA), 4-aminocinnamic acid (4ACA), or polyimides derived from cyclobutanetetracarboxylic dianhydride and aminocinnamate derivatives.

[0123] The organic particles may be selected to enhance the ability of the sub-pixel to withstand thermal stress. Examples of suitable elastomeric polymers include polyethers, polybutadiene, fluororubbers, perfluororubbers, ethylene / acrylic acid copolymers, ethylene propylene diene terpolymers, nitriles and polythiolamines, and combinations of any of the foregoing.

[0124] The inorganic particles can be configured to increase the absorption cross section of the quantum dots, thereby improving the wavelength conversion efficiency of the quantum dots. For example, the efficiency enhancing inorganic particles can include silver or gold. The wavelength conversion efficiency enhancing particles can include solid silver or gold particles, or can include solid organic or inorganic particles with a silver or gold coating.

[0125] Particles that reflect incident radiation, such as blue light, may also reduce the transmission of incident light through a sub-pixel by increasing internal reflection of the incident radiation within the sub-pixel.

[0126] The sub-pixels may include an organic matrix material in which a plurality of quantum dots are embedded. The matrix material may include a cross-linkable material such as a thermosetting material. The matrix material may initially have a low viscosity and may be curable upon exposure to, for example, thermal energy or actinic radiation such as UV radiation. The matrix material may include a compound capable of chemically reacting with the quantum dots, the spacer particles, other components of the sub-pixels, and / or reactive ligands on the sidewalls of the sub-pixels.

[0127] It may be desirable for the matrix material to be stable to subsequent processing, including semiconductor processing conditions.

[0128] The subpixels may be configured to transmit radiation. For example, a color conversion subpixel may radiate in a blue wavelength range. The non-color conversion subpixel may be configured to transmit blue light and include a material that transmits radiation in a blue wavelength range of, for example, 405 nm to 475 nm. The blue transmission subpixel may include, for example, silicon dioxide, such as silicon dioxide particles or silicon dioxide films. The particles may be configured to produce a transmission pattern similar to an emission pattern, the emission pattern being similar to the emission pattern of the color conversion subpixel.

[0129] The conversion efficiency of a sub-pixel may depend on the conversion efficiency of the quantum dots as well as geometric factors.

[0130] For example, the conversion efficiency can be determined by the following factors: (1) the geometric pattern of the incident excitation radiation; (2) losses at the entrance interface of the subpixel, which include absorption, reflection, and the geometry of the entrance; (3) absorption and scattering of the excitation radiation by the subpixel sidewalls and bulk matrix material; (4) the absorption cross section of the quantum dots at the excitation wavelength; (5) the efficiency of the quantum dots with respect to non-radiative processes; (6) the emission pattern of the quantum dots, which can depend on, for example, the shape and composition of the quantum dots; (7) the energy difference between the excitation wavelength and the emission wavelength; (8) the recycling of light within the subpixel, which includes the effects of the coatings on either end of the subpixel and the reabsorption of the quantum dots; and (9) the emission distribution at the subpixel exit, which happens to be one of the most important factors.

[0131] The conversion efficiency of quantum dots may depend on a variety of factors, such as local heating, thermal conduction, heat dissipation, material absorption, bleaching of quantum dots, and / or the creation and / or activation of defects in quantum dots.

[0132] The plurality of sub-pixels may have any suitable configuration. For example, the plurality of sub-pixels may be arranged in a square matrix, a triangular matrix, a hexagonal matrix, or other regular matrix patterns.

[0133] Some of the plurality of sub-pixels may have different sizes than other sub-pixels in the plurality of sub-pixels, including different heights and / or widths. Different sub-pixel sizes may be used to provide sub-pixels with different intensities or saturations.

[0134] The plurality of sub-pixels may be arranged in, for example, a regular array, a regular pattern, or an irregular pattern.

[0135] The plurality of sub-pixels may include one or more sub-pixel groups, wherein each of the one or more sub-pixel groups emits or transmits radiation of a different wavelength.

[0136] The plurality of sub-pixels may include, for example, a sub-pixel group capable of providing radiation in a blue wavelength range, a sub-pixel group capable of providing radiation in a green wavelength range, and a sub-pixel group capable of providing radiation in a red wavelength range.

[0137] The subpixel group capable of providing radiation in the red and green wavelength ranges may include a plurality of quantum dots capable of converting incident radiation in the blue wavelength range. The subpixel group capable of providing radiation in the blue wavelength range may transmit blue radiation.

[0138] The plurality of sub-pixels may include, for example, a group of sub-pixels including a plurality of quantum dots capable of emitting radiation within a wavelength range of 515 nm to 565 nm when illuminated by blue light within a wavelength range of 405 nm to 475 nm.

[0139] The plurality of sub-pixels may include, for example, a group of sub-pixels including a plurality of quantum dots capable of emitting radiation within a wavelength range of 595 nm to 635 nm when illuminated by blue light within a wavelength range of 405 nm to 475 nm.

[0140] The plurality of sub-pixels may include, for example, a group of sub-pixels including a plurality of quantum dots capable of emitting radiation in the wavelength range of 450nm to 475nm when illuminated by blue light in the wavelength range of 405nm to 475nm, with the 2-sigma point of the long wavelength tail of the excitation wavelength being less than the emission wavelength.

[0141] The plurality of sub-pixels may include, for example, a group of sub-pixels including a plurality of quantum dots capable of emitting radiation within a wavelength range of 650 nm to 750 nm when illuminated by blue light within a wavelength range of 405 nm to 475 nm.

[0142] The plurality of sub-pixels may include, for example, a group of sub-pixels including a plurality of quantum dots capable of emitting radiation within a wavelength range of 650 nm to 750 nm when illuminated by blue light within a wavelength range of 470 nm to 620 nm.

[0143] The plurality of sub-pixels may include, for example, a sub-pixel group including a plurality of quantum dots capable of transmitting blue light in a wavelength range of 405 nm to 475 nm.

[0144] For example, the plurality of sub-pixels may include: a first sub-pixel group, wherein each sub-pixel in the first sub-pixel group includes a first plurality of quantum dots, and when being irradiated with blue light in the wavelength range of 405nm to 475nm, the first plurality of quantum dots can emit green light in the wavelength range of 515nm to 565nm; a second sub-pixel group, wherein each sub-pixel in the second sub-pixel group includes a second plurality of quantum dots, and when being irradiated with blue light in the wavelength range of 405nm to 475nm, the second plurality of quantum dots can emit red light in the wavelength range of 595nm to 635nm; and a third sub-pixel group, wherein each sub-pixel in the third sub-pixel group includes a third plurality of quantum dots, and the third plurality of quantum dots can convert violet light in the wavelength range of 400nm to 425nm into blue light in the wavelength range of 450nm to 475nm.

[0145] Each group of sub-pixels can be independently configured into an array, which can be the same as or different from another sub-pixel array.

[0146] Each group of sub-pixels in the plurality of sub-pixels may be configured in any suitable tiled arrangement suitable for providing a display.The sub-pixel array may be interleaved to provide a full color display.

[0147] Some of the plurality of sub-pixels forming the color converter may not include quantum dots. Sub-pixels without quantum dots do not convert incident radiation to another wavelength, but are intended to transmit light, such as light in the blue wavelength range, through the sub-pixel. Such sub-pixels may be filled with, for example, an organic material that transmits light in the blue wavelength range, such as a material with a transmittance greater than 90%, greater than 95%, or greater than 99%.

[0148] The color converter may include, for example, 10 sub-pixels to 1,000,000 sub-pixels, such as 100 sub-pixels to 750,000 sub-pixels, 1,000 sub-pixels to 500,000 sub-pixels, or 10,000 sub-pixels to 100,000 sub-pixels. The color converter may include, for example, more than 10 sub-pixels, more than 1,000 sub-pixels, more than 10,000 sub-pixels, more than 100,000 sub-pixels, more than 500,000 sub-pixels, or more than 1,000,000 sub-pixels. The color converter may include, for example, less than 2,000,000 sub-pixels, less than 1,000,000 sub-pixels, less than 500,000 sub-pixels, less than 100,000 sub-pixels, less than 10,000 sub-pixels, less than 1,000 sub-pixels, or less than 100 sub-pixels.

[0149] The PPI (pixels per linear inch) of the color converter may be, for example, 100 to 50,000, 1,000 to 50,000, 5,000 to 50,000, or 10,000 to 50,000.

[0150] The PPI of the color converter may be, for example, 100 to 5,000, 200 to 5,000, or 500 to 5,000.

[0151] The present disclosure provides color converters having a thickness less than 10 μm and a PPI greater than 10,000.

[0152] To achieve this, it is desirable that the color converter is a single-pass device and has minimal blue light transmission for the color subpixels. For example, for red and green subpixels illuminated with blue light, it is desirable that the subpixels do not include a wavelength selective filter, less than 5% of the blue light is transmitted through each subpixel, corresponding to 95% color conversion purity (95 red photons divided by 95 red + 5 blue photons), and the emission distribution is relatively narrow. Significant improvements in overall efficiency can be achieved by narrowing the emission angle. For example, a hemispherical emitter radiates to slightly above 6sr. An emission cone with an included angle of 66° subtends 1sr.

[0153] To facilitate integration of the color converters provided by the present disclosure, it is desirable that the materials used can withstand the temperatures of semiconductor processes, such as temperatures greater than 200°C.

[0154] However, if the sub-pixels include organic materials such as quantum dots and coatings and / or ligands on an organic matrix material, the sub-pixels may not be able to withstand the temperatures of semiconductor processes. However, organic materials that can withstand higher temperatures are desired.

[0155] The color converter may include a color conversion layer including a plurality of sub-pixels and one or more additional layers.

[0156] The color converter may include a substrate below the color conversion layer. The substrate may be a sacrificial layer used to manufacture the color conversion layer. The substrate may include an inorganic substrate such as a semiconductor substrate or a metal substrate.

[0157] The color converter can include a passivation layer over the color conversion layer. The passivation layer can be used to planarize the color conversion layer and / or protect the color conversion layer during subsequent processing steps.

[0158] The color converter may include a wavelength selective region above the color conversion layer and / or below the color conversion layer. The wavelength selective region may include, for example, a Bragg reflector. The lower wavelength selective region may be configured to transmit blue light and reflect green light or red light. The upper wavelength selective region may be configured to transmit red light or green light and reflect blue light.

[0159] An example of a color converter including a wavelength selective layer is Figure 2 Shown in. Figure 2 The color converter shown includes a transparent layer 201, a release layer 202, a first wavelength selective region 203 below the color conversion layer 204, a passivation layer or sealing layer 205, and a second wavelength selective region 206 above the passivation layer 205, wherein the color conversion layer 204 includes a green sub-pixel 204a, a red sub-pixel 204b, and a blue sub-pixel 204c. The transparent layer 201 may include, for example, sapphire; and the release layer 202 may include, for example, GaN or SOI.

[0160] The first wavelength selection region 203 may be configured to transmit, for example, blue light within a first wavelength range and reflect green and red light. The second wavelength selection region 205 may be configured to reflect blue light within a first wavelength range and transmit green, red, and blue light within a second wavelength range. The thickness of the color conversion layer and the pixel may be, for example, 0.5 μm to 2 μm.

[0161] The color conversion layer may include aluminum or other metal between the individual sub-pixels.

[0162] The second wavelength selective region may have different properties on different sub-pixels. For example, the lateral portion of the second wavelength selective region above the green and red sub-pixels may be configured to reflect incident blue radiation and transmit green and red radiation emitted by the sub-pixels containing quantum dots. The lateral portion of the second wavelength selective region above the blue sub-pixel may be configured to transmit incident blue radiation; or it may not exist, and the region above the blue sub-pixel may be filled with an optically transmissive material such as SiO2.

[0163] The wavelength selective region above the color conversion layer may be configured, for example, to reflect light with a wavelength less than 460 nm.

[0164] The wavelength selective region may include a Bragg reflector and be fabricated using any suitable combination of materials, such as SiO2, TiO2, hafnium oxide, tantalum oxide, and aluminum oxide.

[0165] The wavelength selective region may include a surface configured to reduce dispersion of light emitted and / or transmitted by the color converting layer.

[0166] The color converter may include the above lens array, the lens array including a plurality of lenses. The plurality of lenses may be aligned with respective sub-pixels and may be configured to narrow the dispersion of radiation emitted from the pixels. Examples of suitable nanostructured surfaces include nanometer-thick metal layers configured to enhance surface plasmon enhanced emission.

[0167] The color converter may include a decoupling layer below the color conversion layer. The decoupling layer may minimize the coupling of light transmitted from one subpixel to another subpixel. The decoupling layer may include, for example, silicon dioxide, inorganic oxides, ceramics, metal oxides, non-stoichiometric suboxides, silicones, sulfones, or other suitable organic materials.

[0168] It is contemplated that the quantum dot-containing sub-pixels in the ultra-high density color converter include high density quantum dots.

[0169] Depositing quantum dot-containing materials into cavities using conventional inkjet methods can be challenging due to the high viscosity of the material resulting from the high concentration of quantum dots, and because the quantum dots may become trapped within the cavity. Inkjet deposition under vacuum can reduce air entrapment, at least to some extent.

[0170] A high density of quantum dots is obtained by preparing an ink including quantum dots, depositing the ink into a subpixel cavity, and removing at least some of the matrix material from the cavity without removing the quantum dots. Removal of the matrix material can be accomplished using gel deposition by an infiltration method, for example, as described in U.S. Application No. 16 / 172,562, entitled “Methods for Modifying Material Layer Composition,” filed on October 26, 2018, which is incorporated herein by reference in its entirety.

[0171] High density quantum dots can be obtained by filling the sub-pixel cavity with quantum dots and then inserting an adhesive into the cavity. The adhesive can be inserted throughout the sub-pixel free volume between quantum dots, or can be used as a cover layer and inserted into the upper part of the sub-pixel.

[0172] High density quantum dots can be obtained by filling the sub-pixel cavity with a combination of quantum dots and binder particles. The binder particles are dispersed in the sub-pixel cavity along with the quantum dots.

[0173] High density quantum dots can be obtained by filling the sub-pixel cavity with quantum dots including reactive ligands.

[0174] The binder, whether in the form of ink, intercalated binder, binder particles or reactive ligands, can crosslink with the sub-pixels to fix the quantum dots. The binder reaction can be initiated, for example, using actinic radiation such as UV radiation or heat, depending on the curing chemistry employed.

[0175] Ink including quantum dots can be deposited into the sub-pixel cavity using, for example, roller coating, by wiping an elastic blade on the surface of the color conversion layer or by brushing to press the ink into the cavity. A vacuum can be used to facilitate the ability of high viscosity quantum dot-containing ink to fill high aspect ratio cavities.

[0176] As free-flowing microparticles, quantum dots can be deposited into sub-pixels using a microfluidic deposition method, where the sub-pixel cavity is filled through a flow channel and then covered with a binder to fix the particles. Filling the pixel with free-flowing quantum dots minimizes the vol% of binder in the sub-pixel, thereby increasing the density of quantum dots in the sub-pixel.

[0177] The color converter can be manufactured by, for example, depositing an aluminum layer on a substrate to define a plurality of sub-pixels; depositing a first plurality of quantum dots in a first plurality of sub-pixels; depositing a second plurality of quantum dots in a second plurality of sub-pixels; and depositing a light-transmitting material in a third plurality of sub-pixels to provide three color vertices that form a color gamut of the color converter.

[0178] The substrate may include: an Al2O3 layer; a Si3N4 lift-off layer on the Al2O3 layer; and a SiO2 layer on the Si3N4 lift-off layer.

[0179] The thickness of the aluminum layer may be 1 μm to 3 μm.

[0180] The plurality of 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.

[0181] Where appropriate, the color converter may include additional layers such as reflective layers, passivation layers, and sub-pixel crosstalk reduction layers.

[0182] To assemble the color converter onto an LED array, the color converter may be separated from the substrate by activating the release layer and aligning and then bonding the separated color converter onto the LED array.

[0183] Example

[0184] Embodiments provided by the present disclosure are further illustrated by reference to the following examples, which describe methods, compositions and devices provided by the present disclosure. It will be apparent to those skilled in the art that many modifications can be made to both materials and methods without departing from the scope of the present disclosure.

[0185] Example 1

[0186] FIG. 3A to FIG. 3J Blue light is shown being transmitted through an array of sub-pixels having different sizes and different pitches. FIG. 3A to FIG. 3E The sub-pixels shown each have: 9.6 μm diameter, 12.5 μm pitch ( Figure 3A ); 3.6μm diameter, 6μm pitch ( Figure 3B ); 1.4μm diameter, 3.3μm pitch ( Figure 3C ); 1.4μm diameter, 2.8μm pitch ( Figure 3D ); 1.4μm diameter, 2.3μm pitch ( Figure 3E ).

[0187] FIG. 3F to FIG. 3J The corresponding sub-pixel array is shown magnified 200 times.

[0188] Example 2

[0189] Figure 4 Shown is a sub-pixel window with a diameter of 1.4 μm and a pitch of 2.8 μm, magnified 500 times.

[0190] Example 3

[0191] FIG. 5A to FIG. 5C Blue, green and red sub-pixels are shown respectively. The sub-pixels have a diameter of 9.6 μm and a thickness of 2 μm. Figure 5A Blue light is shown being transmitted through the sub-pixel array from the underlying LED array. Figure 5B Green light emitted by quantum dots illuminated by blue LED light is shown. The quantum conversion efficiency of blue light to green light is 74%, and the blue light leakage is 12%. Figure 5C The red light emitted by quantum dots illuminated by blue LED light is shown. The quantum conversion efficiency of blue light to red light is 57%, and the blue light leakage is 21%.

[0192] Sub-pixels containing green and red quantum dots are made by pressing ink containing quantum dots into wells.

[0193] Example 4

[0194] FIG. 6A to FIG. 6C A sub-pixel array with a depth of 2 μm and a diameter of 2.8 μm is shown ( Fig. 6A and Figure 6B ) and a 3.3μm diameter sub-pixel array ( Figure 6C ). Magnifications are 200x and 500x (inset).

[0195] Example 5

[0196] Figure 7 An example of a color conversion layer with a sub-pixel cavity is shown. 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 including sub-pixels 705 separated by aluminum 706, and a 0.2 μm thick SiO2 layer. Sub-pixels 795 are filled with a composition containing quantum dots, and sub-pixels 795 are 0.7 μm wide on a 1.3 μm pitch.

[0197] Example 6

[0198] FIG. 8A to FIG. 8F An example of steps for manufacturing a color converter is shown. Fig. 8A Details of a substrate 801 are shown, which includes an Al2O3 wafer 802, a 0.1 μm thick Si3N4 layer 803, and a 0.5 μm thick SiO2 layer 804. Figure 8B In FIG. 8 , an aluminum layer 805 has been deposited on a substrate 801. An etch resist 806 has optionally been deposited on the aluminum layer 805 and the chrome etch mask 807. Figure 8C The structure is shown after etching to define sub-pixels 808. Fig.8D As shown, some sub-pixels are filled with red-emitting quantum dot components 809. Then, as Fig. 8E As shown, the red sub-pixel is coated with a protective layer 810 such as SiO2, and as shown in FIG. Fig.8F As shown, a green emitting quantum dot component 811 is deposited in a selected sub-pixel. A blue transmissive sub-pixel 812 may be filled with a transmissive material and the color conversion layer coated with a passivation layer (not shown).

[0199] Finally, it should be noted that there are alternative ways to implement the embodiments disclosed herein. Therefore, the present embodiments should be considered illustrative rather than restrictive. Furthermore, the claims are not limited to the details given herein, but also enjoy their full scope and their equivalents.

Claims

1. A color converter for an ultra-high density light emitting diode array, comprising: substrate; A color conversion layer, wherein the color conversion layer comprises: The first sub-pixel group on the substrate, wherein Each subpixel in the first subpixel group includes a first plurality of quantum dots; The first sub-pixel group emits light within a first wavelength range; and Each sub-pixel independently consists of: Less than 30μm 3 Volume; Thickness of 1 μm to 3 μm; Pitch less than 5 μm; and The density of the quantum dots is in the range of 10 vol% to 50 vol%, Wherein vol% is based on the total volume of the quantum dots minus any ligands or other interstitial materials divided by the total volume of the sub-pixel.

2. The color converter according to claim 1, characterized in that The aspect ratio of each sub-pixel is 2:1 to 10:

1.

3. The color converter of claim 1 further comprising additional subpixel groups, one for each subpixel making up a color pixel, wherein the additional subpixel groups are configured to transmit light in additional wavelength ranges.

4. The color converter according to claim 3, wherein: One of the additional sub-pixel groups does not include quantum dot color conversion material and is configured to pass a pump wavelength.

5. The color converter according to claim 1, wherein Light within the first wavelength range, light within the second wavelength range, and light within the third wavelength range define three color vertices that characterize the color gamut of the color converter.

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

7. The color converter according to claim 1, characterized in that The PPI of the color conversion layer is 100 to 50,000.

8. The color converter according to claim 1, characterized in that The emission cone of each sub-pixel in the first sub-pixel group is less than 66°.

9. The color converter according to claim 1, wherein: Each sub-pixel includes a plurality of conversion enhancing particles.

10. The color converter according to claim 1, wherein Each sub-pixel includes a binder.

11. The color converter according to claim 1, wherein The first plurality of quantum dots includes spacer ligands.

12. The color converter according to claim 1, wherein The first plurality of quantum dots includes reactive ligands.

13. The color converter according to claim 12, wherein The reactive ligand is configured to chemically react with the binder, the particle, the sidewall, a complementary reactive ligand, and / or a ligand of the quantum dot, and / or a coating of the quantum dot.

14. The color converter according to claim 1, wherein When illuminated by light in the wavelength range of 405nm to 475nm, each sub-pixel in the first sub-pixel group and each sub-pixel in the second sub-pixel group exhibits a color conversion efficiency greater than 70%; and a color purity greater than 90%, corresponding to a transmittance of the pump light through the sub-pixel of less than 10%.

15. The color converter according to claim 1, wherein When illuminated by blue light in the wavelength range of 405nm to 475nm, the first sub-pixel group can emit green light in the wavelength range of 515nm to 565nm; and the second sub-pixel group can emit red light in the wavelength range of 565nm to 650nm.

16. The color converter according to claim 1, wherein The first sub-pixel group is interlaced with the second sub-pixel group.

17. The color converter of claim 1, further comprising a passivation layer below the color conversion layer and / or a passivation layer above the color conversion layer.

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

19. The color converter of claim 1, further comprising an optical decoupling layer beneath the color conversion layer.

20. The color converter of claim 15, further comprising a structural layer on the color conversion layer, wherein: The structure layer is configured to focus light emitted by the first sub-pixel group.

21. An optical display comprising: Light emitting diode array; as well as The color converter of claim 1, being on top of and optically coupled to said LED array.

22. The optical display of claim 21, comprising a circuit layer underlying and electrically interconnected with the LED array.

23. An electronic device comprising the optical display of claim 21.

24. A method for manufacturing a color conversion layer, comprising: depositing an aluminum layer on the substrate to define a plurality of cavities; depositing a first color converting material into a first portion of the plurality of cavities, wherein the first color converting material comprises a first plurality of quantum dots; as well as depositing a second color converting material into a second portion of the plurality of cavities, wherein the second color converting material comprises a second plurality of quantum dots; Wherein, each cavity of the plurality of cavities comprises: Less than 30μm 3 Volume; Depth of 1 μm to 3 μm; Pitch less than 5 μm; and The density of the quantum dots is in the volume range of 10 vol% to 50 vol%, wherein vol% is based on the total volume of the cavity.

25. The method of claim 24, further comprising depositing a color transmissive material into a third portion of the plurality of cavities, to provide three color vertices that characterize the color gamut of the color converter.

26. The method of claim 24, further comprising initiating polymerization after depositing the second color conversion material.

27. The method according to claim 24, wherein: Depositing the first color converting material includes depositing by gel infiltration.

28. The method of claim 24, wherein: Depositing includes applying an ink including a plurality of quantum dots into the cavity.

29. The method of claim 24, wherein: Depositing includes depositing a free-flowing composition including quantum dots into the cavity.

30. A color converter made by the method of claim 24.

31. A display comprising the color converter of claim 30.

Images