Light emitting device including quantum dot color conversion material and method for producing same

Abstract

A method of forming a light emitting device includes providing a free-standing support comprising a matrix material including first and second vias; depositing a first photocurable quantum dot ink into the first vias, the first quantum dot ink including a first quantum dot suspended in a first photocurable polymer; irradiating the first photocurable quantum dot ink with ultraviolet or blue light from a first LED of an array of LEDs to crosslink the first photocurable polymer material in the first vias; depositing a second photocurable quantum dot ink into the second vias, the second quantum dot ink including a second quantum dot suspended in a second photocurable polymer material; irradiating the second photocurable quantum dot ink with ultraviolet or blue light from a second LED of the array of LEDs to crosslink the second photocurable polymer material in the second vias; and attaching the free-standing support to the array of LEDs after irradiation.

Description

[Technical field]

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 330,407, filed April 13, 2022, which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to light emitting devices, and in particular to light emitting diodes optically coupled with color conversion materials and methods for making the same. [Background technology]

[0003] Light-emitting diodes (LEDs) are used in electronic displays such as backlighting for LCD displays in laptops and televisions, as well as in augmented reality (AR) displays. Such AR displays are predicted to be very high ppi (2000-8000) with high resolution and small size using micro LEDs with widths of 10 microns or less, such as 1-2 microns. Summary of the Invention

[0004] An embodiment method of forming a light emitting device includes providing a free-standing support comprising a matrix material including first and second vias; depositing a first photocurable quantum dot ink including a first plurality of quantum dots suspended in a first photocurable polymer material within the first vias in the matrix material; irradiating the first photocurable quantum dot ink with ultraviolet or blue light from a first light emitting diode of an array of light emitting diodes to crosslink the first photocurable polymer material in the first vias; depositing a second photocurable quantum dot ink including a second plurality of quantum dots suspended in a second photocurable polymer material configured to emit light of a different peak wavelength than the first plurality of quantum dots within the second vias in the matrix material; irradiating the second photocurable quantum dot ink with ultraviolet or blue light from a second light emitting diode of the array of light emitting diodes to crosslink the second photocurable polymer material in the second vias; and attaching the free-standing support to the array of light emitting diodes after irradiating the first and second photocurable quantum dot inks.

[0005] Another embodiment method of forming a light emitting device includes providing a plurality of light emitting diodes on a substrate, the plurality of light emitting diodes configured to emit incident photons of blue light or ultraviolet radiation; providing a color conversion element including a color conversion material formed in a plurality of vias in a matrix material, the color conversion material in each of the plurality of vias configured to absorb incident photons from a corresponding one of the plurality of light emitting diodes and generate converted photons having a peak wavelength longer than a peak wavelength of the incident photons; positioning the color conversion element relative to the plurality of light emitting diodes such that each of the plurality of vias is located over a corresponding one of the plurality of light emitting diodes; and adjusting a position of the color conversion element relative to the plurality of light emitting diodes to maximize an intensity of the converted photons having the longer peak wavelength.

[0006] In one embodiment, the light emitting device includes a substrate, a plurality of light emitting diodes disposed on the substrate and configured to emit incident photons of blue or ultraviolet radiation, and a color conversion element including a color conversion material disposed in a plurality of vias in a matrix material, each of the plurality of vias being positioned over a corresponding one of the plurality of light emitting diodes, the color conversion material in each of the plurality of vias being configured to absorb incident photons from a corresponding one of the plurality of light emitting diodes and generate converted photons having a peak wavelength longer than the peak wavelength of the incident photons, and the color conversion element is a freestanding structure mounted over the plurality of light emitting diodes. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a side cross-sectional view of an intermediate structure that may be used in forming a light-emitting device, according to various embodiments. [Diagram 2] FIG. 2 is a side cross-sectional view of a light-emitting device according to various embodiments. [Diagram 3] FIG. 3 is a side cross-sectional view of an intermediate structure that may be used in forming a color conversion element, according to various embodiments. [Figure 4] FIG. 4 is a side cross-sectional view of a further intermediate structure that may be used in forming a color conversion element according to the first embodiment. [Diagram 5] FIG. 5 is a side cross-sectional view of a further intermediate structure that may be used in forming a color conversion element according to the first embodiment. [Figure 6] FIG. 6 is a side cross-sectional view of a further intermediate structure that may be used in forming a color conversion element according to the first embodiment. [Figure 7] FIG. 7 is a side cross-sectional view of a further intermediate structure that may be used in forming a color conversion element according to the first embodiment. [Figure 8] FIG. 8 is a side cross-sectional view of a further intermediate structure that may be used in forming a color conversion element according to the first embodiment. [Figure 9] FIG. 9 is a side cross-sectional view of a further intermediate structure that may be used in forming a color conversion element according to the first embodiment. [Figure 10] FIG. 10 is a side cross-sectional view of a color conversion element according to various embodiments. [Figure 11] FIG. 11 is a side cross-sectional view of a further intermediate structure that may be used in forming a color conversion element according to the second embodiment. [Figure 12] FIG. 12 is a side cross-sectional view of a further intermediate structure that may be used in forming a color conversion element according to the second embodiment. [Figure 13] FIG. 13 is a side cross-sectional view of a further intermediate structure that may be used in forming a color conversion element according to the second embodiment. [Figure 14] FIG. 14 is a side cross-sectional view of a further intermediate structure that may be used in forming a color conversion element according to the second embodiment. [Figure 15] FIG. 15 is a side cross-sectional view of a further intermediate structure that may be used in forming a color conversion element according to the second embodiment. [Figure 16] FIG. 16 is a side cross-sectional view of a further intermediate structure that may be used in forming a color conversion element according to the second embodiment. [Figure 17] FIG. 17 is a side cross-sectional view of further intermediate structures that may be used in forming color conversion elements, according to various embodiments. [Figure 18] FIG. 18 is a side cross-sectional view of a further intermediate structure that may be used in forming a color conversion element, according to various embodiments. [Figure 19] FIG. 19 is a side cross-sectional view of a light-emitting element in a first configuration according to various embodiments. [Figure 20] FIG. 20 is a further side cross-sectional view of a light-emitting element in a second configuration according to various embodiments. [Figure 21] FIG. 21 is a further side cross-sectional view of a light-emitting element in a third configuration, according to various embodiments. [Figure 22] FIG. 22 is a side cross-sectional view of a packaged light emitting device in one configuration according to various embodiments. [Figure 23]FIG. 23 is a side cross-sectional view of a packaged light emitting device in another configuration according to various embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A display device, such as a direct-view display (e.g., an AR display), may be formed from a regular array of pixels. Each pixel may include a collection of subpixels that emit light at a respective peak wavelength. For example, a pixel may include a red subpixel, a green subpixel, and a blue subpixel. Each subpixel may include one or more light-emitting diodes that emit light at a particular wavelength. A conventional arrangement is to have red, green, and blue (RGB) subpixels in each pixel. Each pixel is driven by a backplane circuit such that any combination of colors within the color gamut may be displayed on the display for each pixel. A display panel may be formed by soldering or otherwise electrically attaching LED subpixels to bond pads on a backplane. The bond pads may be electrically driven by the backplane circuit and other driving electronics.

[0009] Various embodiments provide light emitting devices configured to use photonically excited quantum dots to generate highly efficient red, green, blue, and / or other color pixelated light from shorter wavelength excitation sources. In an embodiment, micro-scale light emitting diodes (micro LEDs) are less than 10 microns in length and width, e.g., 1-2 microns, and can be used in AR displays and other display devices. This new technology allows high black levels to be achieved by using individual LEDs at each pixel location of the display device. Additionally, each pixel can be configured to generate a single color of light. The backplane on which the individual LEDs are mounted may include a substrate (e.g., plastic, glass, semiconductor, etc.) with thin film transistor (TFT) structures, silicon CMOS, or other driver circuitry configured to apply voltage or current independently to each LED. For example, the backplane may include TFTs on a glass or plastic substrate, or bulk silicon transistors (e.g., transistors in CMOS configuration) on a bulk silicon substrate or on a silicon-on-insulator (SOI) substrate. It should be noted that although micro-LEDs are described in the following embodiments, other types of LEDs (e.g., nanowire or other nanostructure LEDs) or macro-LEDs having sizes (e.g., width and length) greater than 10 microns can be used instead of or in addition to micro-LEDs.

[0010] In some embodiments, the size of each micro LED may be smaller than the pitch of a pixel used in a particular display device, such as a direct-view display device or other display device. For example, a 2000-8000 ppi AR display may have adjacent micro LEDs spaced less than 1 micron apart, e.g., 0.6-0.7 microns apart. It is difficult to sequentially place many different color micro LEDs (e.g., sequentially place red, green, and blue light emitting LEDs) with high precision in adjacent RGB subpixel regions of the same pixel on a backplane.

[0011] Some of the embodiments of the present disclosure include photonic emitters based on LEDs having an undoped GaN active region (e.g., a micro-LED having a GaN light-emitting active layer) or a low indium-doped InGaN active region (e.g., a micro-LED having a low indium content InGaN light-emitting active layer) coupled with a photonically excited color conversion material. Such LEDs may emit ultraviolet (UV) radiation or blue light having a peak emission wavelength in the ultraviolet (UV) radiation or blue light spectral region (e.g., 370-460 nm, e.g., 390-420 nm, e.g., 400-410 nm). As used herein, the blue light spectral region includes the colors blue and violet as perceived by a human observer.

[0012] In some embodiments, the color conversion material may include quantum dots, which may be configured to absorb photons generated by the monochrome LED and generate various colors of light (e.g., red, green, and blue) depending on the properties of the quantum dots (e.g., size and material composition of the quantum dots).

[0013] In size regimes used for augmented reality (AR) displays (e.g., smart glasses) and other applications (e.g., sizes below 10 microns), the use of UV or blue light emitting LEDs and photoexcited quantum dots to produce a variety of colors can provide display devices with better uniformity across the backplane. By placing all adjacent monochromatic LEDs (e.g., either UV or blue LEDs) simultaneously on the backplane (e.g., from the same growth substrate), tighter tolerances can be met more easily than by sequentially placing adjacent red, green and blue LEDs in adjacent subpixels of the same RGB pixel. Embodiments of the present disclosure provide a method for using a monochromatic LED array and fabricating and aligning the quantum dots in the subpixels to allow for improved alignment between the monochromatic LEDs and the respective quantum dots in each color subpixel.

[0014] 1 is a vertical cross-sectional view of an intermediate structure 100 that may be used in forming a light-emitting device, according to various embodiments. The intermediate structure 100 may include a number of LEDs 102 disposed on a substrate 104, such as a backplane. As discussed above, the LEDs 102 may include LEDs having peak emission wavelengths in the UV radiation or blue light spectral region (e.g., UV or blue emitting LEDs, also referred to as UV or blue LEDs).

[0015] In an embodiment, the LEDs 102 may have at least one first electrode 103 located on the top of the LED and facing away from the substrate 104. The first electrode 103 may be configured as an anode electrode or a cathode electrode. In an embodiment, the LEDs 102 may be configured as vertical LEDs with the second electrode 105 located between the substrate 104 and the bottom surface of the LED 102. For example, the second electrodes 105 may be bonded to respective bonding pads on the substrate 104. In another embodiment, the LEDs 102 may include a common transparent first electrode 103 (e.g., a transparent conductive oxide electrode) located on its light-emitting side (e.g., the top side of FIG. 1 ) and a separate second electrode 105 that controls whether each LED 102 is turned on or off. In another embodiment, the LEDs may be configured as horizontal LEDs with both electrodes located on the same side of the LED (e.g., the top or bottom side of the LED).

[0016] The substrate 104 may be a backplane having electrical circuitry (e.g., TFT circuitry and / or CMOS circuitry) configured to provide voltage and current to the LEDs 102 via the second electrodes 105, thereby controlling light emission by the LEDs 102. The backplane may be an active matrix or passive matrix backplane substrate for driving LEDs. As used herein, "backplane substrate" refers to any substrate configured to mount multiple devices thereon. In an embodiment, the backplane may include a substrate comprising silicon, glass, plastic, and / or other material capable of providing structural support to at least the elements mounted thereon. In an embodiment, the backplane substrate may be a passive backplane substrate in which a metal interconnect structure (not shown) including metallization lines is present, for example in a crisscross pattern, and there is no dedicated active element (e.g., TFT) for each LED. In another embodiment, the backplane substrate may be an active backplane substrate, which includes a metal interconnect structure as a cross-grid of conductive lines and may further include dedicated active elements (e.g., CMOS transistors or TFTs) for each LED at one or more intersections of the cross-grid of conductive lines.

[0017] FIG. 2 is a vertical cross-sectional view of a light-emitting device according to various embodiments. The light-emitting device 200 may include an intermediate structure 100 (see, for example, FIG. 1) including a substrate 104 and a plurality of LEDs (102, 102a, 102b, 102c) formed on the substrate 104. Note that in FIG. 2, the second electrode 105 is omitted for clarity. As described above, the LED 102 may be configured to emit blue or ultraviolet radiation incident photons 204. The light-emitting device 200 may further include a color conversion element 201. In an embodiment, the color conversion element 201 is a free-standing element fabricated using radiation emitted by the LED 102 of the intermediate structure 100. In other words, the color conversion element 201 is not deposited layer by layer on the intermediate structure 100, but is formed separately from the intermediate structure 100 so as not to require the intermediate structure 100 for support. The completed color conversion element 201 is then attached to the intermediate structure 100 using adhesives and / or mechanical attachment to form the light emitting element 200.

[0018] The color conversion element 201 includes a color conversion material (202a, 202b, 202c) formed in a plurality of vias 302 in a matrix material (as described below with respect to FIG. 3). As described in more detail below, the color conversion element 201 may optionally include a substrate 212 supporting the plurality of vias 302 surrounded by walls 210 of matrix material. The substrate 212 and walls 210 may be made of different materials or may be formed of the same material. The color conversion element 201 may further include an optional protective layer 214 that is transparent to the incident photons 204. The protective layer may include aluminum oxide or other transparent material.

[0019] The light emitting element 200 may be configured as a regular array. For example, the first color conversion material 202a may be configured to absorb incident photons 204 and generate converted photons 206 having a first color. Similarly, the second color conversion material 202b may be configured to absorb incident photons 204 and generate converted photons 206 having a second color, and the third color conversion material 202c may be configured to absorb incident photons 204 and generate converted photons 206 having a third color. Some of the incident photons 204 may be reflected by the substrate 212, thereby becoming reflected photons 208. The reflected photons 208 may recirculate within the color conversion materials (202a, 202b, 202c), thereby increasing the probability that they will be absorbed by the color conversion materials (202a, 202b, 202c) and converted into converted photons 206. This process, sometimes referred to as "photon recycling," may increase the quantum efficiency of the device.

[0020] In some embodiments, the light emitting element 200 may be configured as a regular array of pixels, with each pixel including a red subpixel, a green subpixel, and a blue subpixel. For example, a pixel 203 may include a first (e.g., red) subpixel having a first LED 102a and a corresponding first color (e.g., red) conversion material 202a, a second (e.g., green) subpixel having a second LED 102b and a corresponding second color (e.g., green) conversion material 202b, and a third (e.g., blue) subpixel having a third LED 102c and a third color (e.g., blue) conversion material 202c. In this manner, the color conversion materials (202a, 202b, 202c) in each subpixel may be configured to generate red, green, and blue converted photons 206, respectively. In further embodiments, the light emitting element 200 may be constructed in a variety of other ways. For example, any number of LEDs 102 may be associated with a color conversion material that generates a single color. In this manner, each pixel may have multiple LEDs in each subpixel. Furthermore, the various subpixels may not all have the same number of LEDs. In one embodiment, the LEDs 102a, 102b, 102c may emit radiation of the same peak wavelength (e.g., ultraviolet or blue light). If the LEDs 102a, 102b, 102c emit blue light, the third color (e.g., blue) conversion material 202c may be omitted from the blue subpixel.

[0021] Each of the plurality of vias 302 (see FIG. 3 ) may be disposed over a corresponding one of the plurality of LEDs (102a, 102b, 102c) such that the color conversion material (202a, 202b, 202c) in each of the plurality of vias is configured to absorb incident photons 204 from each corresponding one of the plurality of LEDs 102 and generate converted photons 206 having a peak wavelength longer than the peak wavelength of the incident photons 204. The substrate 212 (if present) is formed of a radiation transmissive material such that the converted photons 206 may be transmitted through the substrate 212.

[0022] As shown in FIG. 2, the color conversion element 201 may be configured as a separate (i.e., freestanding) structure disposed over the LEDs 102. Additionally, the position of the color conversion element 201 relative to the LEDs 102 may be adjusted to maximize the intensity of converted photons 206 having longer peak wavelengths, as described in more detail below with reference to FIGS. 19-21. Additionally, the LEDs 102 may include micro-LEDs, each having a size (i.e., length and width) of about 10 microns or less, such as from about 1 micron to about 2 microns. Additionally, adjacent LEDs 102 may be separated by a distance of 1 micron or less, such as from about 0.6 microns to about 0.7 microns.

[0023] The color conversion material (202a, 202b, 202c) may include quantum dots corresponding to a variety of different colors. In this example, the color conversion material (202a, 202b, 202c) may include a plurality of first quantum dots 202a, a plurality of second quantum dots 202b, and a plurality of third quantum dots 202c, which may be configured to convert UV or blue incident photons 204 into photons having a first, second, and third color, respectively. For example, the first, second, and third colors may have different peak wavelengths in the red, green, and blue spectral ranges. The quantum dots may have diameters in the range of about 1 nm to about 10 nm, e.g., in the range of 2 nm to 8 nm, and may be nanocrystals of compound semiconductor materials, such as III-V semiconductor materials (e.g., indium phosphide as described in U.S. Pat. No. 9,884,763, which is incorporated by reference in its entirety), II-VI semiconductor materials (e.g., core-shell quantum dots of ZnSe, ZnS, ZnTe, CdS, CdSe, etc., as described in U.S. Patent Application Publication No. US2017 / 0250322, which is incorporated by reference in its entirety), and / or I-III-VI semiconductor materials (e.g., AgInGaS / AgGaS core-shell quantum dots, as described in U.S. Pat. No. 10,927,294, which is incorporated by reference in its entirety).

[0024] Quantum dots can emit different colors of light (e.g., red, green, blue) depending on their diameter. Larger quantum dots can emit longer wavelengths of light, and smaller dots can emit shorter wavelengths of light. The quantum dots may be suspended in a material (e.g., a polymer such as polyimide) that has a different (e.g., higher) refractive index than the refractive index of the light extraction material 110. By way of example, the refractive index of the polyimide material may be between 1.6 and 1.75, e.g., about 1.7. If blue LEDs 102 are used, the blue-emitting quantum dots may be omitted.

[0025] Each LED 102 may be configured to emit incident photons 204 within a common or target wavelength range. For example, GaN-based LEDs 102 may emit incident photons 204 having wavelengths in the range of about 370-430 nm, such as about 400 nm to about 410 nm (i.e., in the blue or near ultraviolet portion of the electromagnetic spectrum). The LEDs 102 may exhibit high uniformity and high efficiency.

[0026] FIG. 3 is a vertical cross-sectional view of an intermediate structure 300 that may be used to form the color conversion element 201 shown in FIG. 2, according to various embodiments. The intermediate structure 300 may include a free-standing support including a substrate 212 and a matrix material having a plurality of vias 302 formed therein. The vias 302 may be bounded by walls 210 of the matrix material. The walls 210 and the substrate 212 may be formed of the same material. For example, the intermediate structure 300 may include a polymer material formed by an injection molding process. In other embodiments, the matrix material may include a positive photosensitive polymer 210L formed on the substrate 212 (see, e.g., FIG. 17 and related discussion below). The vias 302 may be formed by selectively exposing portions of the positive photosensitive polymer 210L to blue or UV radiation (see, e.g., FIG. 18 and related discussion below) that acts to generate portions of the uncrosslinked polymer material that can be removed with a solvent. Various other methods of forming the vias 302 in the matrix material are contemplated within the scope of the present disclosure.

[0027] In the first embodiment shown in Figures 4-9, quantum dot ink is selectively deposited in each via 302 and then irradiated. In Figures 11-16, quantum dot ink is non-selectively deposited in each via 302 and then irradiated.

[0028] FIG. 4 is a vertical cross-sectional view of a further intermediate structure 400 that can be used to form a color conversion element 201 (see, for example, FIG. 2) according to a first embodiment. In this embodiment, a first quantum dot ink 402a may be selectively introduced into the first plurality of vias 302 that are intended to contain the first quantum dots 202a. The first quantum dot ink 402a may include quantum dots having a first size and composition suspended in a photocurable polymer material. The first quantum dot ink 402a may be deposited in various ways. For example, the first quantum dot ink 402a may be deposited by an inkjet printing process. The first quantum dot ink 402a may be exposed to blue light or UV radiation, as described in more detail below with reference to FIG. 5, thereby crosslinking the first photocurable polymer material.

[0029] FIG. 5 is a vertical cross-sectional view of a further intermediate structure 500 that may be used in forming the color conversion element 201 (see, e.g., FIG. 2) according to a first embodiment. The intermediate structure 500 may include an LED array (e.g., intermediate structure 100 of FIG. 1) disposed above the intermediate structure 400 of FIG. 4. Although the LED array is shown disposed above the intermediate structure 400 to irradiate the first quantum dot ink 402a, in alternative embodiments, the LED array may be disposed below the substrate 212 of the intermediate structure 400 to irradiate the first quantum dot ink 402a through the substrate 212. The LED array may be used as a manufacturing tool to selectively irradiate the first quantum dot ink 402a. As shown, the first plurality of LEDs 102a may be selectively activated to expose the first quantum dot ink 402a to blue or ultraviolet light 502. In this manner, the blue light or UV radiation 502 may crosslink the first quantum dot ink 402a, thereby forming the first color conversion material 202a. Thus, a first LED 102a (e.g., an LED located at a red subpixel in the final device 201) may be used to expose a first quantum dot ink 402a to form a first (e.g., red) color conversion material 202a in the red subpixel.

[0030] 6 is a vertical cross-sectional view of a further intermediate structure 600 that may be used to form a color conversion element 201 (see, e.g., FIG. 2) according to a first embodiment. As shown, a second quantum dot ink 402b may be introduced into the second plurality of vias 302. The second quantum dot ink 402b may include quantum dots having a second size and composition different from the first size and / or composition suspended in a photocurable polymer material. The second quantum dot ink 402b may be exposed to blue light or UV radiation, as described in more detail below with reference to FIG. 7, thereby crosslinking the second photocurable polymer material.

[0031] FIG. 7 is a vertical cross-sectional view of a further intermediate structure 700 that may be used to form the color conversion element 201 (see, e.g., FIG. 2) according to the first embodiment, which may include an LED array (e.g., intermediate structure 100 of FIG. 1) disposed above or below the intermediate structure 600 of FIG. 6. As shown, the second plurality of LEDs 102b may be selectively activated to expose the second quantum dot ink 402b to blue light or ultraviolet light 502. In this manner, the blue light or UV radiation 502 may crosslink the second quantum dot ink 402b, thereby forming the second color conversion material 202b. Thus, the second LED 102b (e.g., an LED located at a green subpixel in the final device 201) may be used to expose the second quantum dot ink 402b to form the second (e.g., green) color conversion material 202b in the green subpixel.

[0032] 8 is a vertical cross-sectional view of a further intermediate structure 800 that may be used in forming a color conversion element 201 (see, e.g., FIG. 2) according to the first embodiment. As shown, when a third color conversion material 202c is present in the final element 201, a third quantum dot ink 402c may be introduced into the third plurality of vias 302 (see, e.g., FIG. 3). The third quantum dot ink 402c may include quantum dots having a third size and composition different from the first and second sizes and / or compositions suspended in a photocurable polymer material. The third quantum dot ink 402c may be exposed to blue light or UV radiation, as described in more detail below with reference to FIG. 9, thereby crosslinking the third photocurable polymer material.

[0033] FIG. 9 is a vertical cross-sectional view of a further intermediate structure 900 that may be used to form the color conversion element 201 (see, for example, FIG. 2) according to the first embodiment. The intermediate structure 900 may include an LED array (e.g., intermediate structure 100 of FIG. 1) disposed above or below the intermediate structure 800 of FIG. 8. As shown, the third plurality of LEDs 102c may be selectively activated to expose the third quantum dot ink 402c to blue light or ultraviolet light 502. In this manner, the blue light or UV radiation 502 may crosslink the third quantum dot ink 402c, thereby forming the third color conversion material 202c. Thus, the third LED 102c (e.g., an LED located at a blue subpixel in the final device 201) may be used to expose the third quantum dot ink 402c to form the third (e.g., blue) color conversion material 202c in the blue subpixel. Alternatively, if the LED 102 is comprised of a blue LED, the steps of FIG. 8 and FIG. 9 may be omitted.

[0034] FIG. 10 is a vertical cross-sectional view of a color conversion element 201 (see, e.g., FIG. 2) according to various embodiments. As shown, the color conversion element 201 may further include a protective layer 214 formed on the color conversion materials (202a, 202b, 202c). In an embodiment, the protective layer 214 may be a thin layer of Al2O3, which may be deposited using an atomic layer deposition (ALD) process. The protective layer 214 may have a thickness ranging from about 5 nm to about 50 nm. Alternatively, the protective layer 214 may be formed of various other materials using other deposition processes and may have other thicknesses. The protective layer 214 may be configured to protect the color conversion materials (202a, 202b, 202c) while allowing incident photons 204 to pass through the protective layer 214 (see, e.g., FIG. 2).

[0035] 11 is a vertical cross-sectional view of a further intermediate structure 1100 that may be used to form a color conversion element 201 (see, for example, FIG. 2) according to a second embodiment. In this embodiment, a spin-coating process may be used to non-selectively deposit a first quantum dot ink 402a into all of the vias 302 of the intermediate structure 300 of FIG. 3. As described above, the first quantum dot ink 402a may include quantum dots having a first size and composition suspended in a photocurable polymer material. The first quantum dot ink 402a may be exposed to blue light or UV radiation, which crosslinks the first photocurable polymer material, as described in more detail below with reference to FIG. 12.

[0036] FIG. 12 is a vertical cross-sectional view of a further intermediate structure 1200 that can be used to form a color conversion element 201 (see, for example, FIG. 2) according to a second embodiment. The intermediate structure 1200 may include an LED array (e.g., the intermediate structure 100 of FIG. 1) disposed above or below the intermediate structure 1100 of FIG. 11. The LED array may be used as a manufacturing tool to selectively irradiate the first quantum dot ink 402a. As shown, the first plurality of LEDs 102a may be selectively activated to expose the first (e.g., red) quantum dot ink 402a to blue light or ultraviolet light 502. In this manner, the blue light or UV radiation 502 may crosslink the first quantum dot ink 402a in some of the vias 302 (e.g., vias located in red subpixels) (i.e., crosslink the photocurable polymer material of the ink), thereby forming the first color conversion material 202a.

[0037] 13 is a vertical cross-sectional view of a further intermediate structure 1300 that may be used to form a color conversion element 201 (see, e.g., FIG. 2) according to the second embodiment. In this regard, portions of the first quantum dot ink 402a that were not irradiated in the intermediate structure 1200 (see, e.g., FIG. 12) (e.g., the red quantum dot ink located in the vias 302 of the green and blue subpixels) may be selectively removed because the photocurable polymer material of the ink in those vias 302 is not crosslinked by irradiation.

[0038] A spin-coating process may then be used to deposit a second (e.g., green) quantum dot ink 402b into the plurality of vias 302 that were not irradiated in the intermediate structure 1200 of FIG. 12 (i.e., into the vias that are not already filled with the first color conversion material 202a). As described above, the second quantum dot ink 402b may include quantum dots having a second size and composition different from the first size and / or composition suspended in a photocurable polymer material. The second quantum dot ink 402b may be exposed to blue light or UV radiation, as described in more detail below with reference to FIG. 14, thereby crosslinking the second photocurable polymer material.

[0039] FIG. 14 is a vertical cross-sectional view of a further intermediate structure 1400 that can be used to form a color conversion element 201 (see, for example, FIG. 2) according to a second embodiment. The intermediate structure 1400 may include an LED array (e.g., the intermediate structure 100 of FIG. 1) disposed above or below the intermediate structure 1300 of FIG. 13. The LED array may be used as a manufacturing tool to selectively irradiate the second quantum dot ink 402b. As shown, the second plurality of LEDs 102b may be selectively activated to expose the second quantum dot ink 402b to blue or ultraviolet light 502. In this manner, the blue light or UV radiation 502 can crosslink the second quantum dot ink 402b, thereby forming the second color conversion material 202b in each via 302 (e.g., in the via 302 located in the green subpixel).

[0040] 15 is a vertical cross-sectional view of a further intermediate structure 1500 that may be used to form a color conversion element 201 (see, e.g., FIG. 2) according to a second embodiment. Portions of the second quantum dot ink 402b that were not irradiated (cross-linked) in the intermediate structure 1400 (see, e.g., FIG. 14) may be selectively removed.

[0041] If a third color conversion material 202c is included in the final element 201 (e.g., if the LED 102 is a UV LED), then a spin-coating process may be used to deposit a third quantum dot ink 402c into the vias 302 that were not irradiated in the intermediate structure 1400 of FIG. 14 (i.e., into the vias 302 that are not already filled with the first and second color conversion materials 202a and 202b). As described above, the third quantum dot ink 402c may include quantum dots having a third size and composition different from the first and second sizes and / or compositions suspended in a photocurable polymer material. The third quantum dot ink 402c may be exposed to blue light or UV radiation, as described in more detail below with reference to FIG. 16, thereby crosslinking the third photocurable polymer material.

[0042] FIG. 16 is a vertical cross-sectional view of a further intermediate structure 1600 that can be used to form a color conversion element 201 (see, for example, FIG. 2) according to the second embodiment. The intermediate structure 1600 may include an LED array (e.g., intermediate structure 100 of FIG. 1) disposed on the intermediate structure 1500 of FIG. 15. The LED array may be used as a manufacturing tool to selectively irradiate the third quantum dot ink 402c. As shown, the third plurality of LEDs 102c may be selectively activated to expose the third quantum dot ink 402c to blue light or ultraviolet light 502. In this manner, the blue light or UV radiation 502 can crosslink the third quantum dot ink 402c, thereby forming a third color conversion material 202c (e.g., in the vias 302 located in the blue subpixels).

[0043] As discussed above, the intermediate structure 300 of Figure 3 can be formed in various ways in each embodiment. For example, the substrate 212 and the matrix material having the vias 302 formed therein may be formed by an injection molding process using a polymer material. In other embodiments described below, the substrate and matrix material may be different materials.

[0044] Figure 17 is a vertical cross-sectional view of a further intermediate structure 1700 that may be used in forming a color conversion element 201 (see, e.g., Figure 2), according to various embodiments. As shown in Figure 17, the matrix material may include a positive photosensitive polymer (i.e., matrix material) 210L formed on a substrate 212. The substrate 212 may be a transparent polymer material having sufficient mechanical strength to support the positive photosensitive polymer 210L formed thereon.

[0045] 18 is a vertical cross-sectional view of a further intermediate structure 1800 that may be used to form a color conversion element 201 (see, e.g., FIG. 2), according to various embodiments. In this regard, the intermediate structure 1800 may include an LED array (e.g., intermediate structure 100 of FIG. 1) disposed above or below the intermediate structure 1700 of FIG. 17. The LED array may be used as a manufacturing tool to selectively irradiate exposed portions 210X of the positive photosensitive polymer 210L.

[0046] As shown, all of the LEDs 102 may be activated to expose the exposed portions 210X with blue light or UV radiation 502. In this manner, the blue light or UV radiation 502 may crosslink the exposed portions 210X of the positive photosensitive polymer 210L. The exposed portions 210X may then be removed by dissolving with a solvent. After removal of the exposed portions 210X, a plurality of unexposed portions 210U may remain. In this manner, the unexposed portions 210U of the matrix material become the matrix material walls 210 of the intermediate structure 300 of FIG. 3.

[0047] 19-21 are diagrams illustrating methods of alignment between an LED array (e.g., intermediate structure 100 of FIG. 1) and a free-standing color conversion element 201. FIG. 19 is a vertical cross-sectional view of a light-emitting element 200 in a first configuration according to various embodiments, FIG. 20 is a further vertical cross-sectional view of the light-emitting element 200 in a second configuration, and FIG. 21 is a further vertical cross-sectional view of the light-emitting element 200 in a third configuration. The light-emitting element 200 may include an LED array (e.g., intermediate structure 100 of FIG. 1) disposed above or below a color conversion element 201 that includes color conversion materials (202a, 202b, 202c).

[0048] 19, the first plurality of LEDs 102a may be activated to generate first incident photons 204a that may be absorbed by the first color conversion material 202a to generate first converted photons 206a having a first color (e.g., red). The first converted photons 206a may be detected by a photodetector (e.g., a spectrometer) 220 configured to measure the intensity of the first converted photons 206a.

[0049] According to an embodiment, a method for positioning a color conversion element 201 relative to an LED array (e.g., intermediate structure 100 of FIG. 1) includes adjusting a position of the color conversion element 201 relative to the LEDs 102a to thereby maximize an intensity of the first converted photons 206a. The method may include determining a first maximum intensity of the first converted photons 206a as a first function of a position of the color conversion element 201 relative to the first plurality of LEDs 102a along a first direction (e.g., x-direction) 1602 in a two-dimensional plane (e.g., xz plane) parallel to an interface between the color conversion element 201 and the substrate 104 (e.g., parallel to a surface of the protective layer 114). The method may further include determining a second maximum intensity of the first converted photons 206a along a second direction (e.g., the z direction into the plane of FIG. 19) in a two-dimensional plane (e.g., the xz plane) parallel to the interface between the color conversion element 201 and the substrate 104 as a second function of the position of the color conversion element 201 relative to the first plurality of LEDs 102a.

[0050] 20, the second plurality of LEDs 102b may be activated to generate second incident photons 204b that may be absorbed by the second color conversion material 202b to generate second converted photons 206b having a second color. The second converted photons 206b may be detected by a photodetector 220 configured to measure the intensity of the second converted photons 206b.

[0051] According to an embodiment, a method for positioning a color conversion element 201 relative to an LED array (e.g., intermediate structure 100 of FIG. 1) includes adjusting a position of the color conversion element 201 relative to the LEDs 102b to maximize an intensity of the second converted photon 206b. The method may include determining a third maximum intensity of the second converted photon 206b as a third function of a position of the color conversion element 201 relative to the second plurality of LEDs 102b along a first direction 1602 in a two-dimensional plane parallel to an interface between the color conversion element 201 and the substrate 104 (e.g., parallel to a surface of the protective layer 114). The method may further include determining a fourth maximum intensity of the second converted photon 206a as a second function of a position of the color conversion element 201 relative to the second plurality of LEDs 102b along a second direction (e.g., into the plane of FIG. 20) in a two-dimensional plane (e.g., xz plane) parallel to an interface between the color conversion element 201 and the substrate 104.

[0052] 21, a third plurality of LEDs 102c may be activated to generate third incident photons 204c that may be absorbed by a third color conversion material 202c to generate third converted photons 206c having a third color. The third converted photons 206c may be detected with a detector configured to measure the intensity of the third converted photons 206c.

[0053] According to an embodiment, a method for positioning a color conversion element 201 relative to an LED array (e.g., intermediate structure 100 of FIG. 1) includes adjusting a position of the color conversion element 201 relative to the LEDs 102c to thereby maximize an intensity of the third converted photon 206c. The method may include determining a fifth maximum intensity of the third converted photon 206c as a third function of a position of the color conversion element 201 relative to the third plurality of LEDs 102c along a first direction 1602 in a two-dimensional plane parallel to an interface between the color conversion element 201 and the substrate 104 (e.g., parallel to a surface of the protective layer 114). The method may further include determining a sixth maximum intensity of the third converted photon 206c as a second function of a position of the color conversion element 201 relative to the third plurality of LEDs 102c along a second direction (e.g., into the plane of FIG. 21) in a two-dimensional plane (e.g., xz plane) parallel to the interface between the color conversion element 201 and the substrate 104.

[0054] The above-mentioned method determines the first, second, third, fourth, fifth, and sixth positions corresponding to the first, second, third, fourth, fifth, and sixth maximum intensities, respectively. The first, second, third, fourth, fifth, and sixth positions can then be averaged to determine the optimal position of the color conversion element 201 relative to the LED array.

[0055] Alternatively, a first position that maximizes the intensity of a first color may be determined, a second position that maximizes the intensity of a second color may be determined, and a third position that maximizes the intensity of a third color may be determined. The first position, the second position, and the third position may each indicate a two-dimensional position of the color conversion element 201 relative to the multiple LEDs. The optimal position of the color conversion element 201 may then be determined by averaging the first position, the second position, and the third position. In this way, the two positions along two perpendicular directions in the plane obtained for each color become the two-dimensional coordinates of a single point that maximizes the intensity of each color.

[0056] In a further embodiment, the method may include adjusting an orientation angle (not shown) of the color conversion element 201 relative to the array of LEDs. For example, for a fixed position in a two-dimensional plane, the color conversion element 201 may be tilted relative to a plane (e.g., the xy plane) parallel to the interface between the color conversion element 201 and the substrate 104. A first azimuth angle that maximizes the intensity of the first color of the converted photons may be determined, a second azimuth angle that maximizes the intensity of the second color of the converted photons may be determined, and a third azimuth angle that maximizes the intensity of the third color of the converted photons may be determined. An optimal orientation of the color conversion element 201 relative to the LED array may then be determined based on the first orientation angle, the second orientation angle, and the third orientation angle.

[0057] After the freestanding color conversion element 201 is aligned in an optimal position relative to the array of LEDs 102, the color conversion element 201 is attached to the array of LEDs 102 using adhesives and / or mechanical attachment features (e.g., clamps, brackets, housings, etc.). In this manner, the freestanding color conversion element 201 can be better aligned to the LEDs 102 than if layers of color conversion elements were deposited one by one on the LEDs, eliminating the need for a post-fabrication alignment step.

[0058] 22 is a vertical cross-sectional view of a packaged light emitting element 2200 in a configuration according to various embodiments. An optically transparent insulating filler 216, such as silicon oxide or a polymer, may be formed between the LEDs 102. The light emitting element 2200 includes a housing (e.g., package) 218 ​​that is transparent to visible light or has a window at its top that is transparent to visible light. The package 218 may be made of a polymer material. After the optical alignment process described above, the package 218 holds the free-standing color conversion element 201 and the LED array 100 together.

[0059] In an embodiment, alignment protrusions 220 may be used to align the freestanding color conversion element 201 with the LED array 100. The protrusions 220 may be disposed on the top surface of the LED array 100 and inserted into respective grooves on the bottom surface of the freestanding color conversion element 201 to form an interlocking pattern. Alternatively, the protrusions 220 may be located on the top surface of the freestanding color conversion element 201 and inserted into respective grooves on the bottom surface of the LED array 100. Alternatively, the protrusions are located on both surfaces and inserted into opposing grooves on the opposing surfaces. The protrusions 220 may include any material, such as an insulating material, a semiconducting material, a conductive material, etc. For example, the protrusions may include protruding portions in the insulating filler 216 and / or the protective layer 214. The grooves may be formed in the protective layer 214 and / or the insulating filler 216.

[0060] In an alternative embodiment packaged element 2300 shown in FIG. 23, instead of using a dedicated alignment protrusion 220 and corresponding groove, the LED 102 itself can be used as an alignment feature by fitting into a groove in the freestanding color conversion element 201. The groove may be located in the protective layer 214 and / or the color conversion material 202. For example, the color conversion material 202 may be underfilled in the via 302 to leave a groove above the color conversion material 202 between the matrix material walls 210. The protective layer 214 may partially fill the groove, leaving the remaining portion of the groove to be filled with the LED 102. Thus, the groove in this embodiment includes the unfilled portion of the via 302 described above.

[0061] The foregoing description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the disclosed embodiments. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the following claims and the principles and novel features disclosed herein.

Claims

1. A self-supporting support comprising a matrix material including first and second vias is provided, A first photocurable quantum dot ink, comprising a plurality of first quantum dots suspended in a first photocurable polymer material, is deposited within the first via in the matrix material. Irradiating the first photocurable quantum dot ink with ultraviolet or blue light from the first light-emitting diode of the light-emitting diode array to crosslink the first photocurable polymer material in the first via, A second photocurable quantum dot ink, comprising a second plurality of quantum dots suspended in a second photocurable polymer material and configured to emit light with a different peak wavelength than the first plurality of quantum dots, is deposited in the second via within the matrix material. The process involves irradiating the second photocurable quantum dot ink with ultraviolet or blue light from the second light-emitting diode of the array of light-emitting diodes to crosslink the second photocurable polymer material in the second via, The self-supporting support is attached to the array of light-emitting diodes after irradiating the first and second photocurable quantum dot inks, including, A method for forming a light-emitting element.

2. The method according to claim 1, wherein the matrix material further comprises a third via.

3. A third photocurable quantum dot ink, comprising a third plurality of quantum dots suspended in a third photocurable polymer material and configured to emit light with a different peak wavelength than the first and second plurality of quantum dots, is deposited in the third via within the matrix material. The third photocurable quantum dot ink is irradiated with ultraviolet or blue light from the third light-emitting diode of the array of light-emitting diodes to crosslink the third photocurable polymer material in the third via, The method according to claim 2, further comprising attaching the self-supporting body to the array of light-emitting diodes.

4. The method according to claim 3, further comprising forming the first via, the second via, and the third via in a single via-forming operation.

5. The method according to claim 4, wherein the matrix material comprising the first via, the second via, and the third via is formed by injection molding, and the matrix material comprises a polymer material.

6. The method according to claim 3, wherein the matrix material includes a positive-type photosensitive polymer formed on a first substrate.

7. The first, second, and third portions of the positive-type photosensitive polymer are selectively irradiated using the first, second, and third light-emitting diodes of the array of light-emitting diodes, respectively, to form uncrosslinked polymer material in the first, second, and third portions of the matrix material. The uncrosslinked polymer material of the first portion, the second portion, and the third portion is removed, respectively, to form the first via, the second via, and the third via. The method according to claim 6, further comprising:

8. Depositing the first photocurable quantum dot ink within the first via in the matrix material includes selectively depositing the first photocurable quantum dot ink only within the first via, Depositing the second photocurable quantum dot ink in the second via in the matrix material includes irradiating the first photocurable quantum dot ink and then selectively depositing the second photocurable quantum dot ink only in the second via, Depositing the third photocurable quantum dot ink in the third via in the matrix material includes selectively depositing the third photocurable quantum dot ink only in the third via after irradiating the second photocurable quantum dot ink. The method according to claim 3.

9. Depositing the first photocurable quantum dot ink in the first via in the matrix material includes non-selectively depositing the first photocurable quantum dot ink in the first, second, and third vias, then irradiating the first photocurable quantum dot ink, and subsequently removing the uncrosslinked portions of the first photocurable quantum dot ink from the second and third vias. Depositing the second photocurable quantum dot ink in the second via in the matrix material includes irradiating the first photocurable quantum dot ink, then non-selectively depositing the second photocurable quantum dot ink in the second and third vias, and then irradiating the second photocurable quantum dot ink again, and then removing the uncrosslinked portion of the second photocurable quantum dot ink from the third via. Depositing the third photocurable quantum dot ink in the third via in the matrix material includes irradiating the second photocurable quantum dot ink, then depositing the third photocurable quantum dot ink in the third via, and then irradiating the third photocurable quantum dot ink. The method according to claim 3.

10. The method according to claim 1, wherein the self-supporting support comprising the first and second plurality of quantum dots includes a color conversion element.

11. The method according to claim 10, further comprising forming a protective layer on the color conversion element.

12. A protrusion is formed on at least one mating surface of the color conversion element and the array of light-emitting diodes, A groove is formed on at least one mating surface of the color conversion element and the array of light-emitting diodes, The color conversion element is attached to the array of light-emitting diodes such that the protrusions are inserted into each of the grooves and form an interlock pattern for aligning the positions of the color conversion element and the array of light-emitting diodes. The method according to claim 10, further comprising:

13. The first and second vias are partially filled with the crosslinked first and second photocurable polymer materials to leave grooves. The array of light-emitting diodes includes protrusions that are inserted into each groove and form an interlock pattern for aligning the color conversion element and the array of light-emitting diodes. The method according to claim 10.

14. The plurality of light-emitting diodes are arranged on a substrate so that each of them emits incident photons of blue light or ultraviolet radiation, To provide a color conversion element that includes a color conversion material formed in multiple vias within a matrix material, The color conversion material in each of the plurality of vias is configured to absorb the incident photons from each corresponding of the plurality of light-emitting diodes and generate converted photons having a peak wavelength longer than the peak wavelength of the incident photons, and the color conversion element is positioned relative to the plurality of light-emitting diodes such that each of the plurality of vias is located on each corresponding of the plurality of light-emitting diodes, By adjusting the position of the color conversion element relative to the plurality of light-emitting diodes, the intensity of the conversion photons having a longer peak wavelength is maximized. A method for forming a light-emitting element, including the element itself.

15. Adjusting the position of the color conversion element relative to the plurality of light-emitting diodes is, The first maximum intensity of the converted photon is determined as a first function of the position of the color conversion element with respect to the plurality of light-emitting diodes, along a first direction in a two-dimensional plane parallel to the interface between the color conversion element and the substrate. The second maximum intensity of the converted photon is determined as a second function of the position of the color conversion element with respect to the plurality of light-emitting diodes, along a second direction in a two-dimensional plane parallel to the interface between the color conversion element and the substrate. The maximum intensity of the converted photons is determined as a function of the orientation angle of the color conversion element with respect to the plurality of light-emitting diodes in a two-dimensional plane parallel to the interface between the color conversion element and the substrate, The method according to claim 14, further comprising:

16. circuit board and A plurality of light-emitting diodes arranged on the substrate and configured to emit incident photons of blue or ultraviolet radiation, A color conversion element is arranged within multiple vias in a matrix material and includes a color conversion material. Includes, Each of the plurality of vias is positioned above each corresponding of the plurality of light-emitting diodes, and the color conversion material within each of the plurality of vias is configured to absorb the incident photons from each corresponding of the plurality of light-emitting diodes and generate converted photons having a peak wavelength longer than the peak wavelength of the incident photons. The color conversion element is a self-supporting structure mounted on top of the plurality of light-emitting diodes. Light-emitting element.

17. Each of the plurality of light-emitting diodes is configured to have a width of 10 microns or less, and adjacent light-emitting diodes are separated by a distance of 1 micron or less. The aforementioned color conversion material includes quantum dots, The quantum dot is configured to absorb the incident photon and emit the converted photon having one of the colors red, green, and blue. The plurality of vias in the matrix material are arranged as a regular array of pixels, each pixel containing a red subpixel, a green subpixel, and a blue subpixel, and the color conversion material within each subpixel is configured to generate the red, green, and blue conversion photons, respectively. The light-emitting element according to claim 16.

18. At least one of the color conversion element and the plurality of light-emitting diodes includes a protrusion on the mating surface. At least one of the color conversion element and the plurality of light-emitting diodes includes a groove in the mating surface. The protrusions are inserted into their respective grooves to form an interlock pattern for aligning the color conversion element and the plurality of light-emitting diodes. The light-emitting element according to claim 16.

19. The plurality of vias are partially filled with the color-changing material in order to leave grooves. The plurality of light-emitting diodes include projections inserted into their respective grooves to form an interlock pattern for aligning the color conversion element and the plurality of light-emitting diodes. The light-emitting element according to claim 16.

20. The light-emitting element according to claim 16, wherein the color conversion element and the plurality of light-emitting diodes are held together by at least one of an adhesive or a mechanical mounting function.

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