Pixel isolation structure and manufacturing method thereof

Abstract

A processing method is described that includes forming a group of LED structures on a substrate layer to form a patterned LED substrate. The method also includes depositing a light-absorbing material on the patterned LED substrate, where the light-absorbing material includes at least one photo-curable compound and at least one ultraviolet light-absorbing material. The method further includes exposing a portion of the light-absorbing material to patterned light, where the patterned light cures the exposed portion of the light-absorbing material into a pixel-separating structure. The method further includes depositing an isotropic layer on top and sides of the pixel-separating structure, where the LED structure is substantially free of an as-deposited isotropic light-reflecting layer.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Patent Application No. 63 / 406,929, filed September 15, 2022, entitled "PIXEL ISOLATION STRUCTURES AND METHODS OF MAKING THEM," which is incorporated herein by reference in its entirety.

[0002] The present technology relates to displays having pixels that include pixel separation structures to prevent crosstalk between adjacent pixels. [Background technology]

[0003] High-resolution light-emitting diode (LED) displays can contain millions of micron-sized pixels arranged to form a display screen. Traditional LED displays generate color images by filtering white light from an LED light source into red, green, and blue pixels that emit light at various intensities across the display screen. Other LED displays excite organic or inorganic compounds, which then emit specific colors of light, such as red, green, or blue light, depending on the pixel. These LED displays typically require fewer filters to block unwanted colors of light and can produce a more accurate color gamut. However, because these LED displays emit and scatter light in all directions, photoluminescence crosstalk can occur between adjacent pixels, distorting the colors of the displayed image.

[0004] Therefore, there is a need for pixel designs for display devices that include excitable emissive materials that produce images with reduced photoluminescence crosstalk. These and other needs are addressed by the present technology. [Brief explanation of the drawings]

[0005] A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings, in which like reference numerals are used to refer to like components throughout the several views. In some instances, a sub-label is associated with a reference numeral and follows a hyphen to indicate one of multiple similar components. When referring to a reference numeral without specifying an existing sub-label, it is intended to refer to all of such multiple similar components.

[0006] [Figure 1] 1 is a flowchart illustrating selected operations of an exemplary method for fabricating a pixel structure in accordance with embodiments of the present technology. [Figure 2A] 1A-1C are simplified cross-sectional views of stages in the fabrication of an exemplary single pixel structure in accordance with embodiments of the present technology. [Figure 2B] 1A-1C are simplified cross-sectional views of stages in the fabrication of an exemplary single pixel structure in accordance with embodiments of the present technology. [Figure 2C] 1A-1C are simplified cross-sectional views of stages in the fabrication of an exemplary single pixel structure in accordance with embodiments of the present technology. [Figure 2D] 1A-1C are simplified cross-sectional views of stages in the fabrication of an exemplary single pixel structure in accordance with embodiments of the present technology. [Figure 2E] 1A-1C are simplified cross-sectional views of stages in the fabrication of an exemplary single pixel structure in accordance with embodiments of the present technology. [Figure 3] 4 is another flow diagram illustrating selected operations of an exemplary method for fabricating a pixel structure in accordance with embodiments of the present technology. [Figure 4A] 10A-10C are additional simplified cross-sectional views of stages in the fabrication of an exemplary single pixel structure in accordance with embodiments of the present technology. [Figure 4B] 10A-10C are additional simplified cross-sectional views of stages in the fabrication of an exemplary single pixel structure in accordance with embodiments of the present technology. [Figure 4C] 10A-10C are additional simplified cross-sectional views of stages in the fabrication of an exemplary single pixel structure in accordance with embodiments of the present technology. [Figure 4D] 10A-10C are additional simplified cross-sectional views of stages in the fabrication of an exemplary single pixel structure in accordance with embodiments of the present technology. Summary of the Invention

[0007]

[0005] An embodiment of the present technology includes a processing method including forming a group of LED structures on a substrate layer to form a patterned LED substrate. The method also includes depositing a light-absorbing material on the patterned LED substrate, the light-absorbing material including at least one photo-curable compound and at least one ultraviolet light-absorbing material. The method further includes exposing a portion of the light-absorbing material to patterned light, which hardens the exposed portion of the light-absorbing material into a pixel-separating structure. The method further includes depositing an isotropic layer on top and sides of the pixel-separating structure, wherein the LED structure is substantially free of an as-deposited isotropic light-reflecting layer.

[0008] In additional embodiments, depositing a light-absorbing material on the patterned LED substrate includes spin-coating the light-absorbing material on the patterned LED substrate. In further embodiments, at least one photocurable compound in the light-absorbing material includes an epoxy-based photocurable material. In yet further embodiments, at least one ultraviolet light-absorbing compound in the light-absorbing material includes a benzotriazole derivative, a 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] derivative, and a triazine derivative. In yet additional embodiments, the method further includes washing away uncured light-absorbing material from the patterned LED substrate after curing the exposed portion of the light-absorbing material into the pixel separating structure. In further embodiments, depositing an isotropic light-reflecting layer includes directional deposition of an isotropic light-reflecting layer on the top and sides of the pixel separating structure, where the directional deposition does not deposit an isotropic light-reflecting layer over the entire top surface of the LED structure. In yet another embodiment, the pixel separating structure forms a sidewall of a photoluminescent region located on the LED structure of the patterned LED substrate. In yet another embodiment, the pixel separating structures form sidewalls of a photoluminescent region located over an LED structure of a patterned LED substrate.

[0009]

[0009] Additional embodiments of the present technology include a processing method including depositing a light-absorbing material on a substrate, the light-absorbing material including at least one photo-curable compound and at least one ultraviolet light-absorbing compound. The method further includes exposing a portion of the light-absorbing material to patterned light, where the patterned light hardens the exposed portion of the light-absorbing material into a first portion of a pixel separating structure, the first portion of the pixel separating structure forming a sidewall of a photoluminescent region located on the substrate. The method further includes depositing an isotropic light-reflecting layer on the sidewall of the first portion of the pixel separating structure, where the substrate is substantially free of the as-deposited isotropic light-reflecting layer.

[0010] In a further embodiment, the method includes depositing a photoluminescent material on at least a portion of the photoluminescent region to form a photoluminescent component. In an additional embodiment, the method further includes attaching the photoluminescent component to a patterned LED substrate, the patterned LED substrate including a second portion of the pixel separating structure coupled to the first portion of the pixel separating structure along top surfaces of the first and second portions of the pixel separating structure. In yet an additional embodiment, the at least one photocurable compound in the light-absorbing material includes an epoxy-based photocurable material. In yet a further embodiment, the at least one ultraviolet light-absorbing compound in the light-absorbing material includes a benzotriazole derivative, a 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] derivative, and a triazine derivative. In a further embodiment, the deposition of the isotropic light-reflective layer includes directional deposition of the isotropic light-reflective layer on sidewalls of the first portion of the pixel separating structure, the directional deposition not depositing the isotropic light-reflective layer across the entire substrate.

[0011] A further embodiment of the present technology includes a display structure including a light-emitting diode structure operable to generate ultraviolet light, the structure further including a photoluminescent region containing a photoluminescent material and a pixel separating structure including at least one photo-curable compound and at least one ultraviolet light absorbing compound, at least one sidewall of the photoluminescent region including the pixel separating structure, and a light-reflective layer positioned between the photoluminescent material of the photoluminescent region and the pixel separating structure.

[0012] In a further embodiment, the light-emitting diode structure includes a micro light-emitting diode operable to generate ultraviolet light characterized by a wavelength of about 420 nm or less. In yet another embodiment, the photoluminescent material of the photoluminescent region includes a quantum dot material operable to absorb ultraviolet light from the light-emitting diode structure and emit visible light characterized by a wavelength longer than 420 nm. In yet an additional embodiment, the at least one photocurable compound in the light-absorbing material includes an epoxy-based photocurable material. In yet a further embodiment, the at least one ultraviolet light-absorbing compound in the light-absorbing material includes a benzotriazole derivative, a 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] derivative, and a triazine derivative. In yet another embodiment, the light-reflecting layer includes at least one metal compound selected from the group consisting of aluminum, copper, chromium, silver, gold, platinum, and molybdenum.

[0013] The present technology offers several advantages over conventional methods for fabricating pixel structures including a light-emitting diode component and a photoluminescent region containing a photoluminescent material. In conventional fabrication methods, a patterned LED substrate is covered with a silicon-containing passivation film before undergoing a series of photolithographic patterning operations to form a base for an anisotropically deposited reflective light-reflecting layer. Forming a pixel structure including both a light-emitting diode component and a photoluminescent region requires both deposition and removal operations of the passivation film, photolithographic resist, and a portion of the light-reflecting layer. All of these operations significantly reduce the fabrication efficiency of the pixel structure. In contrast, embodiments of the present technology deposit a light-absorbing material that includes both a light-curable compound and an ultraviolet light-absorbing compound that can be cured into a pixel-separating structure. Instead of multiple operations of depositing, patterning, and removing the light-curable material to form the pixel-separating structure, embodiments of the present technology enable the pixel-separating structure to be formed by a single deposition, patterning, and curing of the light-absorbing material. The initial light-absorbing material is wet and spin-coated onto the structured LED substrate, and the uncured portions of the light-absorbing material after patterning can be washed away in a single operation.

[0003] Embodiments of the present technology also include directional deposition of a reflective light-reflecting layer, depositing the layer on portions of pixel separating structures that increase the proportion of light directed toward the displayed image, while leaving other portions of the pixel structures, such as the top surfaces of the light-emitting diode structures, uncoated. This eliminates the need for a separate removal operation to open up the blanket-deposited light-reflecting layer on the surfaces of these LEDs in conventional manufacturing processes to allow LED-generated light to pass through to the photoluminescent regions of the pixel structures. These and other embodiments, along with many of their advantages and features, are described in more detail below in conjunction with the description and accompanying drawings. DETAILED DESCRIPTION OF THE INVENTION

[0014] Technological advances in high-resolution displays include developing micro-light-emitting diodes (μLEDs) from inorganic semiconductor materials and using photoluminescent materials such as quantum dots in displays. μLEDs are made from layers of semiconductor materials, such as indium gallium nitride (InGaN), which can be configured to emit light at a specific peak emission wavelength when excited by an applied electric field. Semiconductor fabrication processes are used to create μLEDs with a longest dimension of approximately 50 μm or less and operable to emit red, green, or blue light. Quantum dots are nanometer-sized particles of inorganic materials that can emit light of a specific color after being excited by more energetic light. The color of the emitted light can depend on one or more properties of the particle, including its size, shape, and composition, among other properties. For quantum dots made from inorganic semiconductor materials, the color of the emitted light is determined by the energy gap between the dot's conduction and valence bands. When a quantum dot is excited, one or more electrons jump from the lower-energy valence band to the higher-energy conduction band. When the excited electrons return to the valence band, the quantum dot emits light whose color depends on the size of the energy gap between the valence band and the conduction band. The narrower the energy gap, the more red-shifted the emitted light is; the wider the energy gap, the more blue-shifted the emitted light is. By tuning one or more properties of the quantum dot that change the energy gap between the conduction and valence bands, quantum dots can be made to emit light of virtually any color within the visible spectrum.

[0015] Further advances have combined μLEDs and quantum dots in high-resolution displays. μLEDs, individually switched on and off by electronic circuitry in a backplane control panel, generate source light that optically excites the quantum dots. Higher-energy μLED source light, such as blue or ultraviolet light, excites the quantum dots, causing them to emit light of specific, lower-energy colors, such as blue, green, orange, or red. The excited quantum dots can emit light with improved emission characteristics, such as a narrower full-width half-maximum wavelength spectrum than μLEDs. Because quantum dots can emit light in more vivid colors, fewer color filters and polarizers are required in displays to block unwanted colored light from contaminating the displayed image.

[0016] Unfortunately, conventional manufacturing methods for fabricating pixel structures containing both μLEDs and photoluminescent regions containing photoluminescent materials involve multiple deposition, patterning, and removal operations to form pixel isolation structures and reflective light-reflecting layers along the stack of μLEDs and photoluminescent regions. These conventional manufacturing methods may include covering the LED structure with a silicon-containing passivation film, such as silicon nitride, to protect the LED structure during the formation of the pixel isolation structure. Conventional manufacturing methods may also include a series of photolithographic patterning scans to form a scaffold for the anisotropically deposited reflective light-reflecting layer. Forming a pixel structure containing both the light-emitting diode component and the photoluminescent region requires both deposition and removal operations for the passivation film, photolithographic resist, and portions of the light-reflecting layer. All of these operations significantly reduce the manufacturing efficiency of pixel structures.

[0017] The present technology addresses these and other problems with manufacturing methods for creating pixel structures by forming pixel separating structures and reflective light-reflecting layers with significantly fewer operations. In embodiments, the present manufacturing method deposits a light-absorbing material that includes both a photo-curable compound and an ultraviolet light-absorbing compound, which can be cured into a pixel separating structure. Instead of multiple operations of depositing, patterning, and removing the photo-curable material to form the pixel separating structure, embodiments of the present technology allow for the formation of the pixel separating structure through a single deposition, patterning, and curing of the light-absorbing material. In additional embodiments, the initial light-absorbing material is wet and spin-coated onto a structured LED substrate, and the uncured portions of the light-absorbing material after patterning can be washed away in a single operation. In further embodiments, directional deposition of the reflective light-reflecting layer can be performed, depositing the light-reflecting layer on portions of the pixel separating structure that increase the proportion of light directed toward the display image, while leaving other portions of the pixel structure uncoated, such as the top surface of the light-emitting diode structure. This eliminates the need for a separate removal operation in conventional manufacturing processes to open up the light-reflecting layer blanket deposited over these LEDs to allow LED-generated light to penetrate to the photoluminescent regions of the pixel structure.

[0018] FIG. 1 illustrates a flow diagram including selected operations in a method 100 for fabricating a pixel structure 200 according to an embodiment of the present technology. Method 100 may or may not include one or more operations prior to the start of the method, including front-end processing, deposition, etching, polishing, cleaning, or any other operations that may be performed before the described operations. The method may include optional operations that may or may not be specifically associated with some embodiments of methods according to the present technology. Method 100 describes operations for forming embodiments of pixel structures, one of which is shown in simplified schematic form as pixel structure 200 in FIG. 2E and another of which is shown as pixel structure 400 in FIG. 4D . The cross-sectional views of pixel structures 200 and 400 in FIGS. 2E and 4D are split-open cross-sectional views showing pixel structures cut between pairs of first and second subpixels and split-open to reveal the linear arrangement of red, green, blue, and blank pixels in cross section. FIGS. 2E and 4D illustrate only partial schematic views with limited detail. In further embodiments not shown, the exemplary pixel structures can include additional layers, regions, and materials having aspects as shown, as well as alternative structural and material aspects that can still benefit from any aspects of the present technology.

[0019] 2A , in operation 105, the method 100 includes forming patterned LED structures 210a-d on a substrate 202. In embodiments, the LED structures 210a-d may be μLED structures operable to emit blue or ultraviolet light. In some embodiments, the substrate 202 may be removed to expose the surface on which the photoluminescent region is formed and the LED structures 210a-d. In additional embodiments, the substrate 202 may form a backplane in electronic communication with the LED structures 210a-d. In further embodiments, the LED structures 210a-d may be operable to emit ultraviolet or blue light. In still further embodiments, the LED structures 210a-d may be operable to emit light characterized by a peak emission wavelength of about 400 nm or less, about 390 nm or less, about 380 nm or less, about 370 nm or less, about 360 nm or less, about 350 nm or less, about 340 nm or less, about 330 nm or less, or less. In additional embodiments, the LED structures 210a-d may be characterized by a width of about 10 μm or less, about 5 μm or less, about 4 μm or less, about 3.5 μm or less, about 3 μm or less, about 2.5 μm or less, about 2 μm or less, about 1.5 μm or less, about 1 μm or less, or less.

[0020] In embodiments, LED structures 210a-d may be gallium and nitrogen-containing LED structures. In further embodiments, LED structures 210a-d may be gallium nitride LED structures epitaxially formed on a substrate or on a previously formed LED structure. In additional embodiments, substrate 202 may be a silicon substrate or a sapphire substrate, among other types of substrates. In still further embodiments, LED structures 210a-d may further include an n-type doped GaN layer and a p-type doped GaN layer. A multiple quantum well (MQW) region is formed between the n-type doped GaN layer and the p-type doped GaN layer where light emitted by LED structures 210a-d is generated. LED structures 210a-d may further include a conductive N-pad contact that forms a path for current through the n-type doped GaN layer. LED structures 210a-d may also include a conductive P-pad contact that forms a path for current through the p-type doped GaN layer. The N-pad and P-pad contacts may be connected to conductive layers within the LED subpixels or directly to contacts in the backplane control circuit. In embodiments, an electrical signal from the control circuit generates a current flow through the LED structures 210a-d, which causes light to be emitted from the MQW regions of the structures. In additional embodiments, the MQW regions are formed to emit light characterized by a reproducible peak intensity wavelength and quantum efficiency in response to an applied electrical signal (e.g., current and / or voltage). In embodiments, the peak intensity wavelength of the light emitted from the MQW regions may be an ultraviolet light wavelength (e.g., a wavelength of light of about 400 nm or less).

[0021] 2B, the method 100 may further include depositing a light-absorbing material 212 on the substrate 202 and the patterned LED structures 210a-d. In embodiments, the light-absorbing material 212 may be applied to the substrate 202 and the patterned LED structures 210a-d as a liquid or wet slurry. In further embodiments, the light-absorbing material 212 may be applied using one or more deposition techniques such as spin-on coating, dip coating, spray-on coating, blade coating, and inkjet coating, among other deposition techniques.

[0022] In an embodiment, the light absorbing material 212 includes at least one photoresist compound and at least one ultraviolet light absorbing compound. In additional embodiments, the photoresist compound can include one or more compounds such as diazonaphthoquinone, bis-benzophenone type photoinitiator, bis(aryl azide) based crosslinker, phenol formaldehyde resin, poly(methyl methacrylate), poly(methyl glutarimide), and different types of SU-8, mixtures of acrylic monomer thiol-ene resins, polysiloxane, polyvinyl cinnamate, among other photoresist compounds.

[0023] In further embodiments, the ultraviolet light absorbing compound in light absorbing material 212 is selected from the group consisting of N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD), N,N'-bis(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB), N,N'-bis(phenanthrene-9-yl)-N,N'-bis(phenyl)-benzidine (PAPB or PPD), 4,7-diphenyl-1,10-phenanthroline (BPhen), bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum (BAlq), tris-(8-hydroxyquinoline)aluminum (Alq), tetracene (CH), among other ultraviolet light absorbing compounds. 12), 4-phenyl (4P), and 6-phenyl (6P), Tinuvin CarboPreotect available from BASF, the Riasorb series of UV Absorbers from Rianlon, titanium oxide, zinc oxide, and carbon black.

[0024] In yet another embodiment, the light absorbing material 212 can include a solvent for the photoresist compound and / or the ultraviolet light absorbing compound. In a further embodiment, the solvent can include gamma-butyrolactone (GBL) and / or cyclopentanone, cyclohexanone, propyl methyl ether acetate, methoxypropyl ether acetate, anisole, toluene, xylene, dimethylformamide, acetone, acetylacetone, methyl ethyl ketone, methyl isobutyl ketone, among other solvents.

[0025] Method 100 may also include, in operation 115, patterning the light-absorbing material 212 and patterned LED structures 210a-d deposited on substrate 202 by exposing the material to patterned light. In an embodiment, the light may pass through a photolithography mask to form the patterned light that is projected onto light-absorbing material 212. In an additional embodiment, the patterned light may cure the light-absorbing material 212 exposed to the light and leave the material not exposed to the light in an uncured state. In a further embodiment, the patterned light may include ultraviolet light having sufficient energy to cure a photocurable compound in light-absorbing material 212, for example, by photochemical crosslinking of the photocurable compound.

[0026] In additional embodiments, the cured portion of the light-absorbing material 212 can form pixel-separating structures 214a-e made from at least one cured photo-curable compound and at least one ultraviolet light-absorbing compound in the light-absorbing material. As shown in FIG. 2C , the pixel-separating structures 214a-e may be formed between adjacent patterned LED structures 210a-d. In additional embodiments, the pixel-separating structures 214a-e may also be formed in interstitial spaces between the patterned LED structures 210a-d and the substrate 202. In still other embodiments, the pixel-separating structures 214a-e may be characterized as a light-absorbing barrier operable to absorb high-energy ultraviolet light and wavelengths of about 350 nm or less, about 340 nm or less, about 330 nm or less, about 320 nm or less, about 310 nm or less, about 300 nm or less, about 290 nm or less, about 280 nm or less, about 270 nm or less, about 260 nm or less, about 250 nm or less, or less. In further embodiments, the pixel separating structures 214a-e can absorb about 50% or more, about 60% or more, about 70% or more, about 80% or more, about 90% or more, about 92.5% or more, about 95% or more, about 99% or more, or more, of the high energy ultraviolet light that reaches the barrier.

[0027] The method 100 may also include, in operation 120, removing the uncured light-absorbing material 212. In embodiments, the uncured light-absorbing material 212 may be removed by a wet rinse operation that rinses the uncured material from the substrate 202 and the patterned LED structures 210a-d. In additional embodiments, removing the uncured light-absorbing material 212 leaves the top surfaces of the LED structures 210a-d free of light-absorbing material. This allows the LED structures 210a-d to emit light in the photoluminescent regions 218a-d without attenuation by the light-absorbing material 212 without an additional removal operation.

[0028] As shown in FIG. 2C , removal of the uncured light-absorbing material 212 leaves pixel separating structures 214a-e positioned between adjacent LED structures 210a-d. In further embodiments, the pixel separating structures extend above the height of the LED structures 210a-d so as to form part of the sidewall portions of the photoluminescent regions 218a-d. In still further embodiments, the pixel separating structures 214a-e may be characterized by a height of about 2.5 μm or more, about 5 μm or more, about 7.5 μm or more, about 10 μm or more, about 12.5 μm or more, about 15 μm or more, about 17.5 μm or more, about 20 μm or more, or more. In still additional embodiments, the pixel separating structures 214a-e may be characterized by a width of about 5 μm or less, about 4.5 μm or less, about 4 μm or less, about 3.5 μm or less, about 3 μm or less, about 2.5 μm or less, about 2 μm or less, or less. In still further embodiments, pixel separating structures 214a-e may be characterized by a height-to-width aspect ratio of about 1.5:1 or greater, about 2:1 or greater, about 2.5:1 or greater, about 3:1 or greater, about 3.5:1 or greater, about 4:1 or greater, about 4.5:1 or greater, about 5:1 or greater, or greater.

[0029] 2D , the method 100 further includes depositing an isotropic light-reflective layer 220 on portions of the pixel separating structures 214a-e. In the embodiment shown in FIG. 2D , the isotropic light-reflective layer 220 is deposited on the top and side surfaces of the pixel separating structures 214a-e, but not on the top surfaces of the LED structures 210a-d adjacent to the photoluminescent regions 218a-d. In the embodiment, the absence of a light-reflective layer on the top surfaces of the LED structures 210a-d eliminates the need for a patterning etch operation to remove the light-reflective layer from the top surfaces, leaving the light-reflective layer on the surfaces of the pixel separating structures 214a-e.

[0030] In embodiments, deposition of the isotropic light-reflective layer 220 may include sputtering or otherwise directing metal onto the pixel separating structures 214a-e at an angle other than 90° relative to the substrate 202. In further embodiments, the substrate 202 may be rotated during deposition of the isotropic light-reflective layer 220 to cover a greater portion of the sidewalls of the pixel separating structures 214a-e and reduce thickness non-uniformities of the light-reflective layer in the direction of non-orthogonal metal deposition. In further embodiments, the metal forming the light-reflective layer 220 may be selected from the group consisting of aluminum, copper, chromium, silver, gold, platinum, and molybdenum. In still further embodiments, the light-reflective layer 220 is operable to directly or indirectly reflect light in a direction that increases the efficiency of the pixel structures in converting generated light into a displayed image. In embodiments, a portion of the light generated by the LED structures 210a-d that is initially directed away from the photoluminescent regions 218a-d may be redirected by the light-reflective layer 220 toward these photoluminescent regions. In additional embodiments, a portion of the light generated by the photoluminescent materials 222a-c in the photoluminescent regions 218a-c that is initially directed away from the displayed image can be redirected by the light reflecting layer 220 toward the displayed image.

[0031] In additional embodiments, the light-reflecting layer 220 may have a reflective efficiency of about 50% or more, about 60% or more, about 70% or more, about 80% or more, about 90% or more, about 95% or more, about 99% or more, or more for reflecting light in the ultraviolet and visible portions of the electromagnetic spectrum. In further embodiments, the light-reflecting layer 220 is operable to direct a majority of the light emitted by the photoluminescent materials 222a-c of the LED structures 210a-d and photoluminescent regions 218a-c toward contributing to the illumination of a device, such as a display or other illuminable device component. In still further embodiments, the light-reflecting layer 220 increases the intensity of light from pixel structures illuminating a device by about 5% or more, about 10% or more, about 15% or more, about 20% or more, about 25% or more, compared to the same pixel structure without the light-reflecting layer.

[0032] 2E, in operation 130, the method 100 also includes depositing photoluminescent materials 222a-c in the photoluminescent regions 218a-c. In embodiments, the photoluminescent materials 222a-c may include organic light-emitting compounds and / or inorganic light-emitting particles known as quantum dots (QDs), which are operable to absorb light emitted from the LED structures 210a-d and emit light having specific color characteristics. In further embodiments, different photoluminescent materials 222a-c may be deposited in each of the photoluminescent regions 218a-c. In yet another embodiment, the pixel structure includes a fourth photoluminescent region 218d in which no photoluminescent material is deposited unless any of the other photoluminescent regions 218a-c are unable to produce light within the expected brightness and color parameters. In this situation, photoluminescent region 218d is filled with the same type of photoluminescent material as the failed photoluminescent region and is operable to act as a replacement for the failed photoluminescent region.

[0033] In further embodiments, the photoluminescent material 222a-c is deposited in photoluminescent regions 218a-c formed in part from pixel separating structures 214a-e coated with a light-reflecting layer 220. In still further embodiments, the pixel separating structures 2114a-e extend above and around the LED structures 210a-d. In yet other embodiments, the subpixel separating structures may extend adjacent to and below the contact regions of the LED structures 210a-d, or may extend further to the backplane of the pixel structures. In still further embodiments, the height of the pixel separating structures 214a-e may be about 2.5 μm or more, about 5 μm or more, about 7.5 μm or more, about 10 μm or more, about 12.5 μm or more, about 15 μm or more, about 17.5 μm or more, about 20 μm or more, or more. In still additional embodiments, pixel separating structures 214a-e can have widths of about 5 μm or less, about 4.5 μm or less, about 4 μm or less, about 3.5 μm or less, about 3 μm or less, about 2.5 μm or less, about 2 μm or less, or less. In still further embodiments, pixel separating structures 214a-e can have height-to-width aspect ratios of about 1.5:1 or more, about 2:1 or more, about 2.5:1 or more, about 3:1 or more, about 3.5:1 or more, about 4:1 or more, about 4.5:1 or more, about 5:1 or more, or more. In further embodiments, pixel separating structures 214a-e reduce crosstalk generated by light from adjacent and nearby pixel structures. In embodiments, the reduction in light intensity from adjacent and nearby pixel structures can be about 50% or more, about 60% or more, about 70% or more, about 80% or more, about 90% or more, about 95% or more, about 99% or more, or more.

[0034] In embodiments, pixel separating structures 214a-e form sidewalls of photoluminescent regions 218a-d, which also include bottom surfaces adjacent the top surfaces of LED structures 210a-d. In further embodiments, the width of the bottom surfaces of photoluminescent regions 218a-d is about 10 μm or less, about 5 μm or less, about 4 μm or less, about 3.5 μm or less, about 3 μm or less, about 2.5 μm or less, about 2 μm or less, about 1.5 μm or less, about 1 μm or less, or less.

[0035] In additional embodiments, the as-deposited photoluminescent material can include one or more photoluminescent precursors in a mixture or slurry including a photocurable fluid and one or more photoluminescent particles or compounds. In further embodiments, the one or more photoluminescent compounds can include quantum dot materials operable to emit light having specific color characteristics when excited by source light. In additional embodiments, these quantum dot materials can include nanoparticles made from one or more types of inorganic semiconductor materials, such as indium phosphide, zinc selenide, zinc sulfide, silicon, silicates, and graphene, as well as doped inorganic oxides, among other semiconductor materials. In further embodiments, the photocurable fluid can include one or more crosslinking compounds, a photoinitiator, and a color conversion agent. In additional embodiments, the crosslinking compound can include a monomer that forms a polymer when cured. In further embodiments, the monomer can include an acrylate monomer, a methacrylate monomer, and an acrylamide monomer. In yet another embodiment, the crosslinking compound can include a negative-tone photocurable material, such as SU-8 photocurable. In further embodiments, photoinitiators can include phosphine oxide compounds and keto compounds, among other types of photoinitiator compounds, that generate radicals that initiate the curing of unsaturated compounds when excited by ultraviolet light. Commercially available photoinitiator compounds include Irgacure 184, Irgacure 819, Darocur 1173, Darocur 4265, Darocur TPO, Omnicat 250, and Omnicat 550, among other photoinitiators.

[0036] When the as-deposited photoluminescent material includes one or more photoluminescent precursors, the precursors may be cured to form photoluminescent materials 220a-c. In embodiments, the curing operation may include exposing the photoluminescent precursors of photoluminescent regions 218a-c to a curing light that converts the photoluminescent precursors to photoluminescent materials 220a-c. In still further embodiments, the curing light may be characterized by a peak emission wavelength that is sufficiently short to activate one or more of the photo-curable compounds in the photo-curable fluid of the photoluminescent precursor. In yet other embodiments, the curing light may be characterized by a peak emission wavelength of about 405 nm or less, about 400 nm or less, about 395 nm or less, about 390 nm or less, about 385 nm or less, about 380 nm or less, about 375 nm or less, about 370 nm or less, about 365 nm or less, about 360 nm or less, about 355 nm or less, about 350 nm or less, about 340 nm or less, about 330 nm or less, about 320 nm or less, about 310 nm or less, about 300 nm or less, or less. In still further embodiments, the curing light may be provided by the LED structure 210. In these embodiments, providing the curing light from the LED structure 210 enables self-alignment of the photoluminescent material 218 in the photoluminescent regions 214a-e with the LED structures 210a-d. Self-alignment of the photoluminescent material with the LED structure becomes increasingly beneficial as the size of the subpixel decreases and pixel density increases.

[0037] 3 and 4A-4D, another embodiment of a method 300 for fabricating a pixel structure 400 in accordance with embodiments of the present technology is shown. In an embodiment, the method 300 includes, in operation 310, depositing a light-absorbing material on a substrate 402. In a further embodiment, the substrate 402 may not include a patterned LED structure, with the patterned LED structure being provided in a separate component attached to a component that includes the substrate 302. In an additional embodiment, the substrate 402 may be a transparent substrate that allows light generated in the photoluminescent regions 418a-d to be transmitted to a displayed image. In yet an additional embodiment, the substrate 402 may be operable to be removed from the photoluminescent regions 418a-d.

[0038] In further embodiments, the light-absorbing material includes at least one photo-curable compound and at least one ultraviolet light-absorbing material. In additional embodiments, the substrate 402 can include a planar region onto which the light-absorbing material can be deposited as a blanket layer. In still additional embodiments, the light-absorbing material can be a liquid or a slurry and can be applied using one or more deposition techniques such as spin-on coating, dip coating, spray-on coating, blade coating, and inkjet coating, among other deposition techniques.

[0039] Method 300 also includes patterning the deposited light-absorbing material in operation 315. In an embodiment, the patterning operation can include passing light through a photolithographic mask to form patterned light that is projected onto the light-absorbing material. In an additional embodiment, the patterned light hardens the light-absorbing material that is exposed to the light, while leaving the material that is not exposed to the light unhardened. In a further embodiment, the patterned light can include ultraviolet light having sufficient energy to harden a photocurable compound in the light-absorbing material, for example, by photochemical crosslinking of the photocurable compound.

[0040] Method 300 further includes, in operation 320, removing the uncured light-absorbing material. In an embodiment, the removal of the uncured light-absorbing material forms spaces for photoluminescent regions 418a-d, as shown in FIG. 4A . In still further embodiments, photoluminescent regions 418a-d may include sidewall regions formed in part by pixel separating structures 414a-e created during patterning of the light-absorbing material deposited on substrate 402. In yet another embodiment, photoluminescent regions 418a-d include a top surface formed in part by the surface of substrate 402 on which the light-absorbing material is deposited. In an embodiment, substrate 402 may be incorporated into the final pixel structure 400 or may be removed and replaced with a different component of the pixel structure.

[0041] The method 300 also includes, in operation 325, depositing an isotropic light-reflective layer 420 on the pixel separating structures 414a-e, as shown in FIG. 4B . In an embodiment, the isotropic light-reflective layer 320 is deposited on the top and side surfaces of the pixel separating structures 414a-e, but not on the surface of the substrate 302 that forms the top surfaces of the photoluminescent regions 418a-d. In an embodiment, the absence of a light-reflective layer on the surface of the substrate 402 eliminates the need for a patterning etch operation to remove the light-reflective layer from the substrate surface, leaving the light-reflective layer on the surfaces of the pixel separating structures 414a-e. In a further embodiment, the metal forming the light-reflective layer 420 may be selected from the group consisting of aluminum, copper, chromium, silver, gold, platinum, and molybdenum. In yet a further embodiment, the light-reflective layer 320 is operable to reflect light directly or indirectly in a direction that increases the efficiency of the pixel structures in converting generated light into a displayed image.

[0042] 4C , in operation 330, the method 300 also includes depositing photoluminescent materials 322a-c in the photoluminescent regions 418a-c. In embodiments, the photoluminescent materials 422a-c may include organic light-emitting compounds and / or inorganic light-emitting particles known as quantum dots (QDs), which are operable to absorb light emitted from the LED structures 410a-d and emit light having specific color characteristics. In further embodiments, different photoluminescent materials 422a-c may be deposited in each of the photoluminescent regions 418a-c. In yet another embodiment, the pixel structure includes a fourth photoluminescent region 418d in which no photoluminescent material is deposited unless any of the other photoluminescent regions 418a-c are unable to produce light within the expected brightness and color parameters. In this situation, photoluminescent region 418d is filled with the same type of photoluminescent material as the failed photoluminescent region and is operable to act as a replacement for the failed photoluminescent region.

[0043] 4D , in operation 335, the method 300 may further include bonding the substrate 402 having the photoluminescent regions 418a-d to the patterned LED substrate 450. In an embodiment, the substrate 402 may be bonded to the patterned LED substrate 450 using a bonding layer 425 that maintains the substrates bonded together in the final pixel structure 400. In an embodiment, the photoluminescent regions 418a-d and the patterned LED substrate 450 may be fabricated separately to accommodate different processing tolerances for the different substrates, such as different thermal budgets and chemical exposures.

[0044] In embodiments of the present technology, pixel structures 200 and 400 can be combined with additional pixel structures to form a display component. In further embodiments, the display component may be incorporated into a display device such as a headset, glasses, a screen, or a monitor, among other display devices. In still further embodiments, a display component including the present pixel structures may be incorporated into a display device for virtual reality and / or augmented reality services.

[0045] In further embodiments, display components incorporating the present pixel structures may be characterized by pixel densities of about 500 pixels per inch (ppi) or greater, about 1000 ppi or greater, about 1500 ppi or greater, about 2000 ppi or greater, about 2500 ppi or greater, about 3000 ppi or greater, about 3500 ppi or greater, about 4000 ppi or greater, about 4500 ppi or greater, about 5000 ppi or greater, or greater. In further embodiments, increasing the pixel density of the display component does not result in a decrease in the brightness of the displayed image produced by the display component. In embodiments, the brightness of the image may be characterized as about 100 nits or greater, about 250 nits or greater, about 500 nits or greater, about 750 nits or greater, about 1000 nits or greater, about 2500 nits or greater, or greater. In still further embodiments, the pixel structure of the present technology may be characterized by an optical density of about 0.5 or greater, about 0.75 or greater, about 0.8 or greater, about 0.9 or greater, about 0.95 or greater, about 0.99 or greater, or greater.

[0046] While several embodiments have been described, those skilled in the art will recognize that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the invention. Moreover, certain well-known processes and elements have not been described to avoid unnecessarily obscuring the invention. Therefore, the above description should not be construed as limiting the scope of the invention.

[0047] Where a range of values ​​is provided, unless the context clearly dictates otherwise, it is understood that each intervening value between the upper and lower limits of that range is also specifically disclosed, to the tenth of the unit of the lower limit. Each smaller range between any stated or intervening value within a stated range and any other stated or intervening value within that stated range is encompassed. The upper and lower limits of these smaller ranges may independently be included or excluded within the range, and each range including either limit, neither limit, or both limits is also encompassed within the invention, subject to any specifically excluded limits within the stated range. When a stated range includes one or both limits, ranges excluding either or both of those included limits are also included.

[0048] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, a reference to "a process" includes a plurality of such processes, a reference to "the pixel structure" includes a reference to one or more pixel structures and equivalents thereof known to those skilled in the art, and so on.

[0049] Additionally, the words "comprise," "comprising," "include," "including," and "includes," when used in this specification and the claims that follow, are intended to specify the presence of stated features, integers, components, or steps, but do not exclude the presence or addition of one or more other features, integers, components, steps, operations, or groups.

Claims

1. forming a group of LED structures on a substrate layer to form a patterned LED substrate; depositing a light-absorbing material on the patterned LED substrate, the light-absorbing material comprising at least one photo-curable compound and at least one ultraviolet light-absorbing compound; exposing portions of the light absorbing material to patterned light, wherein the patterned light cures the exposed portions of the light absorbing material into pixel separating structures; depositing an isotropic light-reflecting layer on top and sides of the pixel separating structure, wherein the LED structure is substantially free of the as-deposited isotropic light-reflecting layer; A processing method comprising:

2. 10. The process of claim 1, wherein said depositing said light absorbing material onto said patterned LED substrate comprises spin coating said light absorbing material onto said patterned LED substrate.

3. The process of claim 1 , wherein the at least one photocurable compound in the light-absorbing material comprises an epoxy-based photocurable material.

4. 10. The method of claim 1, wherein the at least one ultraviolet light absorbing compound in the light absorbing material comprises a benzotriazole derivative, a 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] derivative, or a triazine derivative.

5. 10. The process of claim 1, further comprising washing away the uncured light absorbing material from the patterned LED substrate after curing the exposed portions of the light absorbing material into the pixel separating structures.

6. 2. The processing method of claim 1, wherein the depositing step includes directional deposition of the isotropic light-reflective layer onto the top and sides of the pixel isolation structure, and the directional deposition does not deposit the isotropic light-reflective layer over an entire top surface of the LED structure.

7. 10. The process of claim 1, wherein the pixel isolation structures form sidewalls of photoluminescent regions located over the LED structures of the patterned LED substrate.

8. 8. The method of claim 7, further comprising depositing a photoluminescent material in the photoluminescent region.

9. depositing a light absorbing material on a substrate, the light absorbing material comprising at least one photo-curable compound and at least one ultraviolet light absorbing compound; exposing a portion of the light absorbing material to patterned light, wherein the patterned light hardens the exposed portion of the light absorbing material into a first portion of a pixel separating structure, the first portion of the pixel separating structure forming a sidewall of a photoluminescent region located on the substrate; depositing an isotropic light-reflective layer on the sidewalls of the first portion of the pixel separating structure, the substrate being substantially free of the as-deposited isotropic light-reflective layer; A processing method comprising:

10. 10. The method of claim 9, further comprising depositing a photoluminescent material on at least a portion of the photoluminescent region to form a photoluminescent component.

11. 10. The processing method of claim 9, further comprising attaching the photoluminescent component to a patterned LED substrate, wherein the patterned LED substrate comprises the second portion of the pixel separating structure coupled to the first portion of the pixel separating structure along a top of the first and second portions of the pixel separating structure.

12. 10. The process of claim 9, wherein the at least one photocurable compound in the light absorbing material comprises an epoxy-based photocurable material.

13. 10. The method of claim 9, wherein the at least one ultraviolet light absorbing compound in the light absorbing material comprises a benzotriazole derivative, a 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] derivative, or a triazine derivative.

14. 10. The processing method of claim 9, wherein the depositing step comprises directional deposition of the isotropic light-reflective layer onto the sidewalls of the first portion of the pixel isolation structure, and the directional deposition does not deposit the isotropic light-reflective layer over the entire substrate.

15. a light emitting diode structure operable to generate ultraviolet light; a photoluminescent region comprising a photoluminescent material; a pixel separating structure comprising at least one photo-curable compound and at least one ultraviolet light absorbing compound, wherein at least one sidewall of the photoluminescent region comprises the pixel separating structure; a light-reflecting layer located between the photoluminescent material of the photoluminescent region and the pixel separating structure; A display structure comprising:

16. 16. The display structure of claim 15, wherein the light emitting diode structure comprises a micro light emitting diode operable to produce ultraviolet light characterized by a wavelength of about 420 nm or less.

17. 16. The display structure of claim 15, wherein the photoluminescent material of the photoluminescent region comprises a quantum dot material operable to absorb the ultraviolet light from the light emitting diode structure and emit visible light characterized by a wavelength longer than 420 nm.

18. 16. The display structure of claim 15, wherein the at least one photocurable compound in the light-absorbing material comprises an epoxy-based photocurable material.

19. 16. The display structure of claim 15, wherein the at least one ultraviolet light absorbing compound in the light absorbing material comprises a benzotriazole derivative, a 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] derivative, or a triazine derivative.

20. 16. The display structure of claim 15, wherein the light-reflective layer comprises at least one metal selected from the group consisting of aluminum, copper, chromium, silver, gold, platinum, and molybdenum.

Images