Devices including low-index material layers and methods for fabricating the devices

Abstract

A device includes a substrate, a low-index material layer (LIML), and a luminescent layer. The LIML is proximate the substrate. The LIML includes a plurality of gas filled voids. The luminescent layer is proximate the LIML. The luminescent layer includes luminescent emitter particles. The LIML may include a non-wetting surface.

Description

Attorney Docket No.: SP24-249DEVICES INCLUDING LOW-INDEX MATERIAL LAYERS AND METHODS FOR FABRICATING THE DEVICESCROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Serial No. 63 / 696586 filed on September 19, 2024, the content of which is relied upon and incorporated herein by reference in its entirety.BACKGROUNDField

[0002] The present disclosure relates generally to devices including a low-index material layer. More particularly, it relates to display devices including a low-index material layer including a plurality of gas filled voids.Technical Background

[0003] Optical displays may be continuously refined for higher optical efficiencies providing the viewer with an optimal brightness, color-gamut, high-contrast, and high-resolution experience. Emissive displays may include organic light emitting diodes (OLED) displays, displays based on quantum dot (QD) color converters excited by OLEDs (QD-OLED) or micro LEDs, or electro-luminescent QD (EL-QD or nano-LED) displays. These emissive displays have the advantage of perfect (or near perfect) black levels with the emissive devices switched off. Emissive displays, however, may suffer from some efficiency limitations due to light trapping from total internal reflection (TIR) at the boundary between the higher refractive index emissive layers and the lower refractive index color filter materials or glass and / or at the boundary between the cover glass and air. Some of the light within an emissive display may be trapped by TIR inside the emissive layer, since OLED materials typically have a high refractive index of about 1.8 and QD ink materials typically have a refractive index of about 1.65, both of which are higher than the refractive index of about 1.5 for the cover glass. In addition, some light within the emissive display may be trapped by TIR at the boundary between the cover glass and air, which has a refractive index of about 1.Attorney Docket No.: SP24-249

[0004] Light at high output angles may be trapped inside the cover glass of a display due to total internal reflection (TIR). In displays utilizing QDs, QD in emissive layers emit light randomly in all directions, so that there may be a significant amount of light experiencing TIR. The light reflected back by TIR may be absorbed by a color filter of a different color or the same color resulting in significant loss in the amount of light ultimately emitted by the display.SUMMARY

[0005] Some embodiments of the present disclosure relate to a device. The device includes a substrate, a low-index material layer (LIML), and a luminescent layer. The LIML is proximate the substrate and includes a plurality of gas filled voids. The luminescent layer is proximate the LIML. The luminescent layer includes luminescent emitter particles.

[0006] Yet other embodiments of the present disclosure relate to a display device. The display device includes a substrate, a plurality of walls, a plurality of low-index material layers (LIMLs), and a plurality of luminescent layers. The plurality of walls are proximate the substrate and define a plurality of openings. The plurality of LIMLs are proximate the substrate. Each LIML is within a respective opening of the plurality of openings and includes a plurality of gas filled voids. Each luminescent layer is within a respective opening of the plurality of openings proximate a respective LIML of the plurality of LIMLs and includes luminescent emitter particles.

[0007] Yet other embodiments of the present disclosure relate to a method for fabricating a display device. The method includes forming a low-index material layer (LIML) including a plurality of gas filled voids on a substrate. The method includes applying a photoresist or ink layer on the LIML. The method includes curing the photoresist or ink layer to form a luminescent layer of a color filter layer.

[0008] The devices disclosed herein have increased optical efficiency by including low- index material layers (LIMLs) including gas filled voids, which may form a non-wetting (e.g., super hydrophobic-oleophobic or non-wetting for the material of the next layer) surface exhibiting the Cassie-Baxter state. The non-wetting surface includes a surface porosity that provides the LIML function and prevents a layer (e.g., luminescent layer, color filter layer, adhesive layer, scattering layer) applied on the LIML from filling in the surface porosity. In some embodiments, a blocking layer is applied to the LIML to seal the surface porosity and prevent the layer applied on the LIML from filling in the surface porosity.Attorney Docket No.: SP24-249

[0009] By including a LIML near a luminescent layer, total internal reflection (TIR) loss may be inhibited. Quantum dots (QDs) emit light at all possible angles. Without a LIML, high-angle rays would experience TIR at the glass-air boundary. Those rays may be absorbed by a color filter of a different color or the same color (typical color filters have only about 80 percent to about 90 percent transmission). With the LIML, TIR at the boundary between the QD layer and the LIML recycles the high-angle rays. Those rays may then be converted into low-angle rays and output by the QD layer due to scattering.

[0010] By reducing or eliminating TIR at the glass-air boundary, crosstalk by light traveling to the next pixel of the same color is reduced or eliminated. For a tiled display, such as a micro light emitting diode (LED) display, the edge glow phenomenon caused by light guiding in the color filter glass may also be reduced or eliminated.

[0011] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0012] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary and are intended to provide an overview or framework to understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment s), and together with the description explain principles and operation of the various embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIGS. 1A-1F are simplified cross-sectional views of exemplary devices including low-index material layers;

[0014] FIGS. 2A-2D are simplified cross-sectional views of other exemplary devices including low-index material layers;

[0015] FIGS. 3A-3H are simplified cross-sectional views of exemplary display devices including low-index material layers;

[0016] FIGS. 4A-4D are simplified cross-sectional views of other exemplary display devices including low-index material layers;

[0017] FIGS. 5A-5D are simplified cross-sectional views of other exemplary display devices including low-index material layers;Attorney Docket No.: SP24-249

[0018] FIGS. 6A-6H are simplified cross-sectional views of other exemplary display devices including low-index material layers;

[0019] FIGS. 7A-7D are simplified cross-sectional views of other exemplary display devices including low-index material layers; and

[0020] FIGS. 8A-8G are flow diagrams of exemplary methods for fabricating a display device.DETAILED DESCRIPTION

[0021] Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. However, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0022] Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0023] Directional terms as used herein - for example up, down, right, left, front, back, top, bottom, vertical, horizontal - are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[0024] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus, specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derivedAttorney Docket No.: SP24-249 from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[0025] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to “a” component includes aspects having two or more such components, unless the context clearly indicates otherwise.

[0026] Surface roughness can enhance either wetting or non-wetting characteristics of a substrate. Assuming that the size of a liquid droplet is much larger than that of the roughness features (e.g., pillars, posts, protrusions, pits, depressions and the like), a liquid droplet placed on a roughened surface can assume either of two limiting configurations: the Wenzel state or the Cassie-Baxter state. In the Wenzel state, the liquid droplet fully invades the space between the pillars or protrusions and all the solid surface underneath the liquid drop is wetted by the liquid. Alternatively, a liquid droplet can also assume the Cassie-Baxter state, in which the liquid droplet sits on the top of the rough surface without invading the space between pillars / protrusions. Much of the liquid surface thus can be suspended in air without touching any solid surface. The Cassie-Baxter state is also known as the composite state, as a composite interface, comprising liquid-solid and liquid-air interfaces which coexist to create the overall interface shape. In this instance, a very large contact angle can be attained if much of the liquid surface can be suspended in air. As used herein, a “non-wetting surface” exhibits the Cassie- Baxter state. Similarly, a highly porous material with an open pore structure presents a discontinuous nano-structured surface to the liquid drop placed on it, and thereby may also resist penetration of the liquid into the pores.

[0027] Referring now to FIG. 1A, a simplified cross-sectional view of an exemplary device 100a is depicted. Device 100a may be part of a display device and may provide a color converting function. Device 100a includes a substrate 110, a low-index material layer (LIML) 120, and a luminescent layer 130. The substrate 110 includes a first surface 112 and a second surface 114 opposite to the first surface 112. The LIML 120 includes a first surface 122 and a second surface 124 opposite to the first surface 122. The luminescent layer 130 includes a first surface 132 and a second surface 134 opposite to the first surface 132. The LIML 120 is proximate (e.g., on or contacting) the substrate 110 such that the second surface 114 of the substrate 110 contacts (e.g., directly contacts) the first surface 122 of the LIML 120. The second surface 124 of the LIML 120 includes a non-wetting surface. The first surface 132 of the luminescent layer 130 contacts (e.g., directly contacts) the non- wetting surface 124 of the LIML 120.Attorney Docket No.: SP24-249

[0028] In certain exemplary embodiments, the substrate 110 may include a glass substrate including a glass material, such as aluminosilicate, alkali-aluminosilicate, borosilicate, alkali- borosilicate, aluminoborosilicate, alkali-aluminoborosilicate, soda lime, or other suitable glasses. Non-limiting examples of commercially available glasses suitable for use as a glass substrate 110 include EAGLE XG®, Lotus™, Willow®, Iris™, and Gorilla® glasses from Coming Incorporated. The substrate 110 may have a thickness between the first surface 112 and the second surface 114 within a range, for example, from about 0.1 millimeters to about 2 millimeters. The substrate 110 may have a refractive index within a range, for example, between about 1.45 and about 2.4. In some embodiments, the substrate 110 may be a cover glass for the device 100a.

[0029] The LIML 120 may include a refractive index less than about 1.5, such as within a range, for example, between about 1.05 and about 1.4. The LIML 120 may have a thickness between the first surface 122 and the second surface 124 within a range, for example, from about 1 micrometer to about 10 micrometers. The LIML 120 may include a plurality of gas filled (e.g., air filled) voids (e.g., pores) including surface voids sealed by the luminescent layer 130. In certain exemplary embodiments, the LIML 120 includes nanopillars. In other embodiments, the LIML 120 includes an at least partially decomposed sacrificial material. In yet other embodiments, the LIML 120 includes an aerogel. In yet other embodiments, the LIML 120 includes a mixture of hollow silica nanoparticles and a polymer binder, which includes closed pores such that there may be no need for the non-wetting surface. The second surface 124 of the LIML 120 exhibits the Cassie-Baxter state and includes a highly porous nonwetting surface that provides the LIML function and prevents the luminescent layer 130 from filling in the porous surface.

[0030] The luminescent layer 130 may include a refractive index between about 1.5 and about 1.8. The luminescent layer 130 may have a thickness between the first surface 132 and the second surface 134 within a range, for example, from about 5 micrometers to about 15 micrometers. The luminescent layer 130 may include luminescent emitter particles and scattering particles within a polymer. In certain exemplary embodiments, the luminescent emitter particles may include at least one of quantum dots, phosphors, fluorophores, nanocrystals, organic light emitters, or other suitable luminescent emitter particles. The scattering particles may include high refractive index material particles such as, for example, titania, zirconia, hafhia, or barium titanate. Emissions from the luminescent emitter particles within the luminescent layer 130 are total internal reflected from the LIML 120 back towards the luminescent layer 130 if they are emitted at higher than critical TIR angle. If a sufficientlyAttorney Docket No.: SP24-249 strong scattering is present in the luminescent layer 130 or another layer below the LIML 120, these emissions may assume a more favorable light ray trajectory (lower than critical angle), and exit into the LIML 120 after a round-trip in the structure, an optical effect called “recycling” herein. Once the light exits into the LIML 120, most of the light will traverse the substrate 110 (e.g., cover glass) without experiencing TIR at the glass-air boundary and exit the device 100a, resulting in higher optical efficiency.

[0031] FIG. IB is a simplified cross-sectional view of another exemplary device 100b. Device 100b is similar to device 100a previously described and illustrated with reference to FIG. 1A, except that device 100b includes a blocking layer 150 in addition to the substrate 110, the LIML 120, and the luminescent layer 130. The blocking layer 150 includes a first surface 152 and a second surface 154 opposite to the first surface 152. The blocking layer 150 is between (e.g., directly between) the LIML 120 and the luminescent layer 130, such that the second surface 124 of the LIML 120 contacts (e.g., directly contacts) the first surface 152 of the blocking layer 150, and the first surface 132 of the luminescent layer 130 contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150. The blocking layer 150 may, for example, include silicon dioxide (Si O2). a polymer material, or another suitable material that does not penetrate the gas filled voids (e.g., pores) on the second surface 124 of the LIML 120 but rather seals the gas filled voids. In this embodiment, the luminescent layer 130 may include a material that would penetrate into the gas filled voids on the second surface 124 of the LIML 120 if blocking layer 150 was excluded. Accordingly, by including blocking layer 150, the number of materials suitable for luminescent layer 130 may be increased compared to the number of materials suitable for luminescent layer 130 of device 100a of FIG. 1A. The blocking layer 150 may have athickness between the first surface 152 and the second surface 154 within a range, for example, from about 10 nanometers to about 200 nanometers.

[0032] FIG. 1C is a simplified cross-sectional view of another exemplary device 100c. Device 100c is similar to device 100a previously described and illustrated with reference to FIG. 1A, except that device 100b includes a color filter layer 140 in addition to the substrate 110, the LIML 120, and the luminescent layer 130. The color filter layer 140 includes a first surface 142 and a second surface 144 opposite to the first surface 142. The color filter layer 140 is between (e.g., directly between) the substrate 110 and the LIML 120, such that the second surface 114 of the substrate 110 contacts (e.g., directly contacts) the first surface 142 of the color filter layer 140, and the second surface 144 of the color filter layer 140 contacts (e.g., directly contacts) the first surface 122 of the LIML 120. The color filter layer 140 may, for example, include a red color filter layer, a green color filter layer, and / or a blue color filterAttorney Docket No.: SP24-249 layer. The color filter layer 140 may include color pigments or dyes within a polymer. The color filter layer 140 may have a thickness between the first surface 142 and the second surface 144 within a range, for example, from about 2 micrometers to about 10 micrometers.

[0033] FIG. ID is a simplified cross-sectional view of another exemplary device lOOd. Device lOOd is similar to device 100c previously described and illustrated with reference to FIG. 1C, except that device lOOd includes a blocking layer 150 in addition to the substrate 110, the color filter layer 140, the LIML 120, and the luminescent layer 130. Blocking layer 150 is between (e.g., directly between) the LIML 120 and the luminescent layer 130 of device lOOd as previously described and illustrated with reference to FIG. IB.

[0034] FIG. IE is a simplified cross-sectional view of another exemplary device 100c. Device 100c is similar to device 100c previously described and illustrated with reference to FIG. 1C including a color filter layer 140 in addition to the substrate 110, the LIML 120, and the luminescent layer 130. In this embodiment, however, the color filter layer 140 is between (e.g., directly between) the LIML 120 and the luminescent layer 130, such that the second surface 124 of the LIML 120 contacts (e.g., directly contacts) the first surface 142 of the color filter layer 140, and the second surface 144 of the color filter layer 140 contacts (e.g., directly contacts) the first surface 132 of the luminescent layer 130. The second surface 124 of the LIML 120 includes a non- wetting surface. The first surface 142 of the color filter layer 140 contacts (e.g., directly contacts) the non-wetting surface 124 of the LIML 120 and seals the voids on the second surface 124 of the LIML 120.

[0035] FIG. IF is a simplified cross-sectional view of another exemplary device lOOf. Device lOOf is similar to device 100c previously described and illustrated with reference to FIG. IE, except that device lOOf includes a blocking layer 150 in addition to the substrate 110, the LIML 120, the color filter layer 140, and the luminescent layer 130. Blocking layer 150 is between (e.g., directly between) the LIML 120 and the color filter layer 140, such that the second surface 124 of the LIML 120 contacts (e.g., directly contacts) the first surface 152 of the blocking layer 150, and the first surface 142 of the color filter layer 140 contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150. The blocking layer 150 does not penetrate the gas filled voids (e.g., pores) on the second surface 124 of the LIML 120 but rather seals the gas filled voids. In this embodiment, the color filter layer 140 may include a material that would penetrate into the gas filled voids on the second surface 124 of the LIML 120 if blocking layer 150 was excluded. Accordingly, by including blocking layer 150, the number of materials suitable for color filter layer 140 may be increased compared to the number of materials suitable for color filter layer 140 of device 100c of FIG. IE.Attorney Docket No.: SP24-249

[0036] FIG. 2A is a simplified cross-sectional view of another exemplary device 200a. Device 200a may be part of a display device and may provide a color converting function. Device 200a includes a LIML 120a and a luminescent layer 130. In this embodiment, LIML 120a includes nanopillars 210 separated by voids 212. In certain exemplary embodiments, the nanopillars 210 have a random size (e.g., diameter) and the voids 212 also have a random size within ranges suitable to form non-wetting surface 124 such that luminescent layer 130 does not extend into the voids 212. In this embodiment, the LIML 120a is formed in substrate 110 such that the LIML 120a is integral to the substrate 110. In some embodiments, LIML 120a may form LIML 120 previously described and illustrated with reference to FIGS. 1A, IB, IE, or IF.

[0037] LIML 120a including nanopillars 210 and voids 212 may be formed using a metal dewetting process as will be described below with reference to FIG. 8C. For example, the LIML 120a including nanopillars 210 and voids 212 may be formed using the process described in commonly-assigned U.S. Patent No. 10,898,933 B2, by Adra Smith Baca et al., entitled “Oleophobic Glass Articles,” fded May 30, 2013; U.S. Patent No. 9,296,183 B2, by David Eugene Baker et al., entitled “Metal Dewetting Methods and Articles Produced Thereby,” fded November 28, 2012; and U.S. Patent No. 9,023,457 B2, by Albert Carrilero et al., entitled “Textured Surfaces and Methods of Making and Using Same,” fded November 28, 2012; the contents of each of which are incorporated herein by reference in their entireties. Alternatively, LIML 120a including nanopillars 210 and voids 212 may be formed using photolithography and etching (e.g., dry etching) processes. Due to advances in semiconductor processing technology, sub 10 nanometer dimensional control may be achievable.

[0038] The spacing between neighboring nanopillars 210 should not be too large such that a photoresist or ink might still be able to locally wet the surface 124 of LIML 120a. In addition, the combined volume of the nanopillars 210 should be less than the combined volume of the voids 212, such that the refractive index of the LIML 120a is closer to that of air than to glass.

[0039] Once the LIML 120a is formed, a photoresist or ink including luminescent emitter particles, and in some embodiments scattering particles, may be applied (e.g., via photolithography or printing) on (e.g., directly on) the non-wetting surface 124 of the LIML 120a. Due to the non-wetting surface 124, the fluid droplets of the photoresist or ink do not penetrate into the voids 212. The photoresist or ink may then be cured (e.g., via ultraviolet light) to lock in the droplet geometry of the photoresist or ink to form the luminescent layer 130.Attorney Docket No.: SP24-249

[0040] It is noted that luminescent layer 130 in FIG. 2A (and in FIGS. 2B-2D described below) may be replaced with a color filter layer or an adhesive layer as further described below with reference to FIGS. 3E-3H and 5A-6D. In some embodiments, the color filter layer may be formed similarly to luminescent layer 130 via photolithography or printing.

[0041] FIG. 2B is a simplified cross-sectional view of another exemplary device 200b. Device 200b is similar to device 200a previously described and illustrated with reference to FIG. 2A, except that device 200b includes a blocking layer 150 in addition to the substrate 110, the LIML 120a, and the luminescent layer 130. The blocking layer 150 includes a first surface 152 and a second surface 154 opposite to the first surface 152. The blocking layer 150 is between (e.g., directly between) the LIML 120a and the luminescent layer 130, such that the second surface 124 of the LIML 120a contacts (e.g., directly contacts) the first surface 152 of the blocking layer 150, and the first surface 132 of the luminescent layer 130 contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150. The blocking layer 150 may, for example, include silicon dioxide (SiCL), a polymer material, or another suitable material that does not penetrate the gas filled voids 212 on the second surface 124 of the LIML 120a but rather seals the gas filled voids. In this embodiment, the luminescent layer 130 may include a material that would penetrate into the gas filled voids on the second surface 124 of the LIML 120a if blocking layer 150 was excluded. Accordingly, by including blocking layer 150, the number of materials suitable for luminescent layer 130 may be increased compared to the number of materials suitable for luminescent layer 130 of device 200a of FIG. 2A.

[0042] In some embodiments, the blocking layer 150 may be formed by sputtering a thin (e.g., within a range between about 10 nanometers and about 200 nanometers) and dense layer of blocking material, such as silicon dioxide (SiCL), on the second surface 124 of the LIML 120a to seal the voids 212 of the LIML 120a prior to forming the luminescent layer 130. In other embodiments, the blocking layer 150 may be formed by applying (e.g., printing) a polymer material with long enough chains such that the polymer material will not penetrate into the voids 212 but rather seal the voids of the LIML 120a.

[0043] Once the LIML 120a and the blocking layer 150 are formed, a photoresist or ink including luminescent emitter particles, and in some embodiments scattering particles, may be applied (e.g., via photolithography or printing) on (e.g., directly on) the blocking layer 150. Due to the blocking layer 150, the fluid droplets of the photoresist or ink do not penetrate into the voids 212. The photoresist or ink may then be cured (e.g., via ultraviolet light) to lock in the droplet geometry of the photoresist or ink to form the luminescent layer 130.Attorney Docket No.: SP24-249

[0044] FIG. 2C is a simplified cross-sectional view of another exemplary device 200c. Device 200c may be part of a display device and may provide a color converting function. Device 200c includes a LIML 120b and a luminescent layer 130. In this embodiment, LIML 120b includes a plurality of internal pores 220 and a plurality of surface pores 222 forming the non-wetting surface 124. The plurality of internal pores 220 may be gas filled (e.g., with air). The plurality of surface pores 222 may also be gas filled (e.g., with air) and are sealed by the luminescent layer 130. In certain exemplary embodiments, the plurality of internal pores 220 and the plurality of surface pores 222 have a random size (e.g., length, width, diameter, etc.). The plurality of surface pores 222 each have a random size within a range suitable to form nonwetting surface 124 such that luminescent layer 130 does not extend into the pores 222. In this embodiment, the LIML 120b may be formed on a substrate (e.g., 110 of FIG. 1A), on a color converting layer (e.g., 140 of FIG. 1C), or on another suitable layer. In some embodiments, LIML 120b may form LIML 120 previously described and illustrated with reference to FIGS. 1A-1F.

[0045] LIML 120b including pores 220 and 222 may be formed using any suitable process, examples of which will be described below with reference to FIGS. 8D-8G. For example, LIML 120b may include an at least partially decomposed sacrificial material, an aerogel, or a mixture of hollow silica nanoparticles and a polymer binder. Once the LIML 120b is formed, a photoresist or ink including luminescent emitter particles, and in some embodiments scattering particles, may be applied (e.g., via photolithography or printing) on the non-wetting surface 124 of the LIML 120b. Due to the non-wetting surface 124, the fluid droplets of the photoresist or ink do not penetrate into the surface pores 222. The photoresist or ink may then be cured (e.g., via ultraviolet light) to lock in the droplet geometry of the photoresist or ink to form the luminescent layer 130.

[0046] A LIML 120b formed using aerogel may have a reflective index within a range, for example, between about 1.05 and about 1.15 and a porosity, for example, of up to about 80 percent. Aerogel films are super hydrophobic and may be made even more super hydrophobic by a silane or fluorinated chemical treatment. Depending upon the nature of the material (e.g., ink) used to form the luminescent layer 130, the super hydrophobic LIML 120b might be sufficient to prevent surface pore filling while fabricating the luminescent layer 130 on the aerogel layer. If a solvent-based material (e.g., ink) used to form the luminescent layer 130 is still able to penetrate into the pores (e.g., due to a short length of the base polymer chain), a blocking layer 150 may be added as described below with reference to FIG. 2D.Attorney Docket No.: SP24-249

[0047] An alternative way to prepare the LIML 120b is to deposit a thin layer of sacrificial material with a low boiling, sublimation, or decomposition temperature, or dissolved gas, between the substrate (e.g., 110 of FIG. 1A) and the luminescent layer 130, or between the color filter layer (e.g., 140 of FIG. 1C) and the luminescent layer 130. Upon heating at a sufficiently high temperature or by exposing the sacrificial material to a laser light, the sacrificial material is converted to a vapor, decomposes into two or more vapor phases, or releases the dissolved gas to form a fully or partially gas (e.g., air) filled layer. One example of a material that sublimates even at room temperature is cyclododecane.

[0048] FIG. 2D is a simplified cross-sectional view of another exemplary device 200d. Device 200d is similar to device 200c previously described and illustrated with reference to FIG. 2C, except that device 200d includes a blocking layer 150 in addition to the LIML 120b, and the luminescent layer 130. The blocking layer 150 includes a first surface 152 and a second surface 154 opposite to the first surface 152. The blocking layer 150 is between (e.g., directly between) the LIML 120b and the luminescent layer 130, such that the second surface 124 of the LIML 120b contacts (e.g., directly contacts) the first surface 152 of the blocking layer 150, and the first surface 132 of the luminescent layer 130 contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150. The blocking layer 150 may, for example, include silicon dioxide (SiCh), a polymer material, or another suitable material that does not penetrate the surface pores 222 on the second surface 124 of the LIML 120b but rather seals the surface pores. In this embodiment, the luminescent layer 130 may include a material that would penetrate into the surface pores 222 on the second surface 124 of the LIML 120b if blocking layer 150 was excluded. Accordingly, by including blocking layer 150, the number of materials suitable for luminescent layer 130 may be increased compared to the number of materials suitable for luminescent layer 130 of device 200c of FIG. 2C.

[0049] In some embodiments, the blocking layer 150 may be formed by sputtering a thin (e.g., within a range between about 10 nanometers and about 200 nanometers) and dense layer of blocking material, such as silicon dioxide (SiCh), on the second surface 124 of the LIML 120b to seal the surface pores 222 of the LIML 120b prior to forming the luminescent layer 130. In other embodiments, the blocking layer 150 may be formed by applying (e.g., printing) a polymer material with long enough chains such that the polymer material will not penetrate into the surface pores 222 but rather seal the surface pores of the LIML 120b.

[0050] Once the LIML 120b and the blocking layer 150 are formed, a photoresist or ink including luminescent emitter particles, and in some embodiments scattering particles, may be applied (e.g., via photolithography or printing) on the blocking layer 150. Due to the blockingAttorney Docket No.: SP24-249 layer 150, the fluid droplets of the photoresist or ink do not penetrate into the surface pores 222. The photoresist or ink may then be cured (e.g., via ultraviolet light) to lock in the droplet geometry of the photoresist or ink to form the luminescent layer 130.

[0051] FIG. 3 A is a simplified cross-sectional view of an exemplary display device 300a. In some embodiments, display device 300a is a quantum dot color converting (QD-CC) display device. Display device 300a includes a substrate 110, a LIML 120, a plurality of walls 320 (e.g., pixel walls), a plurality of luminescent layers 330a, an encapsulation layer 322, and an emitter array 339 (e.g., light board) including a plurality of light sources 340. Substrate 110, LIML 120, and each luminescent layer 330a may be similar to substrate 110, LIML 120, and luminescent layer 130, respectively, as previously described and illustrated with reference to FIG. 1A. The first surface 122 of the LIML 120 is proximate (e.g., on or contacting) the second surface 114 of the substrate 110. The second surface 124 of the LIML 120 includes a nonwetting surface. As previously described, the LIML 120 may, for example, include nanopillars, an at least partially decomposed sacrificial material, an aerogel, and / or a mixture of hollow silica nanoparticles and a polymer binder. The LIML 120 may include a plurality of gas filled voids (e.g., pores) sealed by the plurality of walls 320 and the plurality of luminescent layers 330a.

[0052] The plurality of walls 320 may directly contact the non-wetting surface 124 of the LIML 120 and define a plurality of openings 360. Each opening 360 may have a circular, square, rectangular, hexagonal, or other suitable shape. In certain exemplary embodiments, the plurality of walls 320 may include a metal (e.g., Al) or metal veneer, a white or metal particle filled photoresist, or another suitable reflective material. The plurality of walls 320 reflect light rays, thereby further increasing the optical efficiency of the display device 300a. The plurality of walls 320 may be formed using photolithography processes and / or electroplating.

[0053] Each of the plurality of luminescent layers 330a includes a first surface 332 and a second surface 334 opposite to the first surface 332. The first surface 332 of each luminescent layer 330a directly contacts the non-wetting surface 124 of the LIML 120 within a respective opening 360. Each of the plurality of luminescent layers 330a includes luminescent emitter particles and scattering particles within a polymer. The luminescent layers 330a may be formed by printing a photoresist or ink layer including luminescent emitter particles and scattering particles within a curable polymer directly on the non-wetting surface 124 of the LIML 120 within each respective opening 360. Following printing, the photoresist or ink may be cured, such as by an ultraviolet light, to form the luminescent layers 330a. After curing, each luminescent layer 330a includes a fixed geometry.Attorney Docket No.: SP24-249

[0054] Encapsulation layer 322 encapsulates the plurality of walls 320 and the plurality of luminescent layers 330a. Encapsulation layer 322 is between (e.g., directly between) the plurality of walls 320 and the plurality of luminescent layers 330a and the emitter array 339. In certain exemplary embodiments, the encapsulation layer 322 is a thin film encapsulation layer.

[0055] Each of the plurality of light sources 340 may be aligned with a respective opening 360. Each light source 340, respective opening 360, and respective luminescent layer 330a may form a single pixel of the display device 300a. Each of the plurality of light sources 340 may, for example, be an LED (e.g., size larger than about 0.5 millimeters), a mini-LED (e.g., size between about 0.1 millimeters and about 0.5 millimeters), a micro-LED (e.g., size smaller than about 0. 1 millimeter), an organic LED (OLED), or another suitable light source. In certain exemplary embodiments, each of the plurality of light sources 340 is a blue light source.

[0056] FIG. 3B is a simplified cross-sectional view of another exemplary display device 300b. Display device 300b is similar to display device 300a previously described and illustrated with reference to FIG. 3A, except that display device 300b includes a blocking layer 150. The blocking layer 150 includes a first surface 152 and a second surface 154 opposite to the first surface 152. The blocking layer 150 is between (e.g., directly between) the LIML 120 and the plurality of walls 320 and the plurality of luminescent layers 330a, such that the second surface 124 of the LIML 120 contacts (e.g., directly contacts) the first surface 152 of the blocking layer 150, the first surface 332 of each luminescent layer 330a contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150, and the top surface of each wall 320 contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150.

[0057] FIG. 3C is a simplified cross-sectional view of an exemplary display device 300c. Display device 300c is similar to display device 300a previously described and illustrated with reference to FIG. 3A, except that display device 300c includes a plurality of luminescent layers 330b (in place of the plurality of luminescent layers 330a) and an adhesive layer 324. In this embodiment, each of the plurality of luminescent layers 330b includes luminescent emitter particles within a polymer, and not scattering particles. Rather, in this embodiment, adhesive layer 324 includes scattering particles. In certain exemplary embodiments, adhesive layer 324 includes an optically clear adhesive (e.g., silicone, acrylate, urethane, vinyl, ester, etc.) with scattering particles. Adhesive layer 324 is between (e.g., directly between) the encapsulation layer 322 and the emitter array 339.

[0058] FIG. 3D is a simplified cross-sectional view of another exemplary display device 300d. Display device 300d is similar to display device 300c previously described andAttorney Docket No.: SP24-249 illustrated with reference to FIG. 3C, except that display device 300d includes a blocking layer 150. The blocking layer 150 includes a first surface 152 and a second surface 154 opposite to the first surface 152. The blocking layer 150 is between (e.g., directly between) the LIML 120 and the plurality of walls 320 and the plurality of luminescent layers 330b, such that the second surface 124 of the LIML 120 contacts (e.g., directly contacts) the first surface 152 of the blocking layer 150, the first surface 332 of each luminescent layer 330b contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150, and the top surface of each wall 320 contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150.

[0059] FIG. 3E is a simplified cross-sectional view of another exemplary display device 300e. Display device 300e is similar to display device 300a previously described and illustrated with reference to FIG. 3 A, except that display device 300e includes a plurality of color filter layers 140 in the respective plurality of openings 360. Each color filter layer 140 includes a first surface 142 and a second surface 144 opposite to the first surface 142. Each color filter layer 140 is between (e.g., directly between) the LIML 120 and the respective luminescent layer 330a, such that the second surface 124 of the LIML 120 contacts (e.g., directly contacts) the first surface 142 of each color filter layer 140, and the second surface 144 of each color filter layer 140 contacts (e.g., directly contacts) the first surface 332 of the respective luminescent layer 330a. Each color filter layer 140 may, for example, include a red color filter layer, a green color filter layer, and / or a blue color filter layer.

[0060] FIG. 3F is a simplified cross-sectional view of another exemplary display device 300f. Display device 300f is similar to display device 300e previously described and illustrated with reference to FIG. 3E, except that display device 300f includes a blocking layer 150. The blocking layer 150 includes a first surface 152 and a second surface 154 opposite to the first surface 152. The blocking layer 150 is between (e.g., directly between) the LIML 120 and the plurality of walls 320 and the plurality of color filter layers 140, such that the second surface 124 of the LIML 120 contacts (e.g., directly contacts) the first surface 152 of the blocking layer 150, the first surface 142 of each color filter layer 140 contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150, and the top surface of each wall 320 contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150.

[0061] FIG. 3G is a simplified cross-sectional view of an exemplary display device 300g. Display device 300g is similar to display device 300e previously described and illustrated with reference to FIG. 3E, except that display device 300g includes a plurality of luminescent layers 330b (in place of the plurality of luminescent layers 330a) and an adhesive layer 324. In this embodiment, each of the plurality of luminescent layers 330b includes luminescent emitterAttorney Docket No.: SP24-249 particles within a polymer, and not scattering particles. Rather, in this embodiment, adhesive layer 324 includes scattering particles. In certain exemplary embodiments, adhesive layer 324 includes an optically clear adhesive (e.g., silicone, acrylate, urethane, vinyl, ester, etc.) with scattering particles. Adhesive layer 324 is between (e.g., directly between) the encapsulation layer 322 and the emitter array 339.

[0062] FIG. 3H is a simplified cross-sectional view of another exemplary display device 300h. Display device 300h is similar to display device 300g previously described and illustrated with reference to FIG. 3G, except that display device 300h includes a blocking layer 150. The blocking layer 150 includes a first surface 152 and a second surface 154 opposite to the first surface 152. The blocking layer 150 is between (e.g., directly between) the LIML 120 and the plurality of walls 320 and the plurality of color filter layers 140, such that the second surface 124 of the LIML 120 contacts (e.g., directly contacts) the first surface 152 of the blocking layer 150, the first surface 142 of each color filter layer 140 contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150, and the top surface of each wall 320 contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150.

[0063] As illustrated in FIGS. 3A-3H, display devices 300a-300h include a continuous LIML 120, and in some embodiments a corresponding continuous blocking layer 150, that extends over the individual pixels. In these embodiments, the LIML 120 and the blocking layer 150 may be formed on the substrate 110, which may form the cover glass of the display devices.

[0064] FIG. 4A is a simplified cross-sectional view of an exemplary display device 400a. In some embodiments, display device 400a is a quantum dot color converting (QD-CC) display device. Display device 400a includes a substrate 110, a plurality of walls 320 (e.g., pixel walls), a plurality of color filter layers 140, a plurality of LIMLs 120, a plurality of luminescent layers 330a, an encapsulation layer 322, and an emitter array 339 including a plurality of light sources 340. Substrate 110, each color filter layer 140, each LIML 120, and each luminescent layer 330a may be similar to substrate 110, color filter layer 140, LIML 120, and luminescent layer 130, respectively, as previously described and illustrated with reference to FIG. 1C.

[0065] The plurality of walls 320 may contact (e.g., directly contact) the second surface 114 of the substrate 110 and define a plurality of openings 360. Each opening 360 may have a circular, square, rectangular, hexagonal, or other suitable shape. In certain exemplary embodiments, the plurality of walls 320 may include a metal (e.g., Al) or metal veneer, a white or metal particle filled photoresist, or another suitable reflective material. The plurality of walls 320 reflect light rays, thereby further increasing the optical efficiency of the display deviceAttorney Docket No.: SP24-249400a. The plurality of walls 320 may be formed using photolithography processes and / or electroplating.

[0066] Each of the plurality of color filter layers 140 is within a respective opening 360 and includes a first surface 142 and a second surface 144 opposite to the first surface 142. Each of the plurality of LIMLs 120 is within a respective opening 360 and includes a first surface 122 and a second surface 124 opposite to the first surface 122. Each of the plurality of luminescent layers 330a is within a respective opening 360 and includes a first surface 332 and a second surface 334 opposite to the first surface 332. The first surface 142 of each color filter layer 140 contacts (e.g., directly contacts) the second surface 114 of the substrate 110. Each of the plurality of color filter layers 140 includes color pigments or dyes within a polymer. The color filter layers 140 may be formed by printing a photoresist or ink layer including color pigments or dyes within a curable polymer directly on the second surface 114 of the substrate 110 within each respective opening 360. Following printing, the photoresist or ink may be cured, such as by an ultraviolet light, to form the color filter layers 140. After curing, each color filter layer 140 includes a fixed geometry.

[0067] The second surface 144 of each color filter layer 140 contacts (e.g., directly contacts) the first surface 122 of the respective LIML 120. The second surface 124 of each LIML 120 contacts (e.g., directly contacts) the first surface 332 of the respective luminescent layer 330a. The second surface 124 of each LIML 120 includes a non-wetting surface. As previously described, each LIML 120 may, for example, include nanopillars, an at least partially decomposed sacrificial material, an aerogel, and / or a mixture of hollow silica nanoparticles and a polymer binder. Each LIML 120 may include a plurality of gas filled voids (e.g., pores) sealed by the respective luminescent layer 330a.

[0068] The first surface 332 of each luminescent layer 330a directly contacts the non-wetting surface 124 of the LIML 120 within a respective opening 360. Each of the plurality of luminescent layers 330a includes luminescent emitter particles and scattering particles within a polymer. The luminescent layers 330a may be formed by printing a photoresist or ink layer including luminescent emitter particles and scattering particles within a curable polymer directly on the non-wetting surface 124 of the LIML 120 within each respective opening 360. Following printing, the photoresist or ink may be cured, such as by an ultraviolet light, to form the luminescent layers 330a. After curing, each luminescent layer 330a includes a fixed geometry.

[0069] FIG. 4B is a simplified cross-sectional view of another exemplary display device 400b. Display device 400b is similar to display device 400a previously described andAttorney Docket No.: SP24-249 illustrated with reference to FIG. 4A, except that display device 400b includes a plurality of blocking layers 150. Each blocking layer 150 is within a respective opening 360 and includes a first surface 152 and a second surface 154 opposite to the first surface 152. Each blocking layer 150 is between (e.g., directly between) the respective LIML 120 and the respective luminescent layer 330a, such that the second surface 124 of each LIML 120 contacts (e.g., directly contacts) the first surface 152 of the respective blocking layer 150, and the first surface 332 of each luminescent layer 330a contacts (e.g., directly contacts) the second surface 154 of the respective blocking layer 150.

[0070] FIG. 4C is a simplified cross-sectional view of an exemplary display device 400c. Display device 400c is similar to display device 400a previously described and illustrated with reference to FIG. 4A, except that display device 400c includes a plurality of luminescent layers 330b (in place of the plurality of luminescent layers 330a) and an adhesive layer 324. In this embodiment, each of the plurality of luminescent layers 330b includes luminescent emitter particles within a polymer, and not scattering particles. Rather, in this embodiment, adhesive layer 324 includes scattering particles. In certain exemplary embodiments, adhesive layer 324 includes an optically clear adhesive (e.g., silicone, acrylate, urethane, vinyl, ester, etc.) with scattering particles. Adhesive layer 324 is between (e.g., directly between) the encapsulation layer 322 and the emitter array 339.

[0071] FIG. 4D is a simplified cross-sectional view of another exemplary display device 400d. Display device 400d is similar to display device 400c previously described and illustrated with reference to FIG. 4C, except that display device 400d includes a plurality of blocking layers 150. Each blocking layer 150 is within a respective opening 360 and includes a first surface 152 and a second surface 154 opposite to the first surface 152. Each blocking layer 150 is between (e.g., directly between) the respective LIML 120 and the respective luminescent layer 330b, such that the second surface 124 of each LIML 120 contacts (e.g., directly contacts) the first surface 152 of the respective blocking layer 150, and the first surface 332 of each luminescent layer 330b contacts (e.g., directly contacts) the second surface 154 of the respective blocking layer 150.

[0072] An additional advantage of aerogel as the LIML 120 is that aerogel is formed from a solution and therefore can be delivered locally. This allows fabrication of the QD-CC components (e.g., luminescent layers 330a or 330b and color filter layers 140) of the display devices 400a-400d illustrated in FIGS. 4A-4D where the LIML 120 is not a continuous layer covering the second surface 114 of the substrate 110 but rather is fabricated within each pixel between the color filter layers 140 and the luminescent layers 330a or 330b. This furtherAttorney Docket No.: SP24-249 improves the display device efficiency, since the recycled light does not have to double pass the color filter layer 140, which is never completely lossless. Yet another advantage of aerogel is that some minimal penetration into the surface pores by the layer applied on the aerogel (e.g., luminescent layer 330a or 330b) may be tolerated, as long as the applied layer does not fill the volume porosity such that the refractive index of the LIML 120 is increased.

[0073] Y et another advantage of the LIML 120 not being a continuous layer is that it reduces the display reflectivity for ambient light, and therefore improves the display contrast in brightly lit environments. A continuous LIML 120 on the second surface 114 of the substrate 110, such as the structured layer produced by masking and etching of FIGS. 2A and 2B, may add the reflection from both of its surfaces to the reflection from an external surface of the substrate. If the LIML 120 is between the color filter layers 140 and the luminescent layers 330a or 300b, only the ambient light of the respective color can be reflected, somewhat further attenuated by double passing the color filter layer 140. For fabrication convenience, it is feasible to adjust the viscosity of the aerogel solution such that the solution is compatible with an inkjet process, in which case the entire pixel stack including the color filter layer 140, the LIML 120, a blocking layer 150 in some embodiments, and the luminescent layer 330a or 330b can be fabricated sequentially by inkjet printing.

[0074] A light ray that enters the LIML 120 at lower than the TIR critical angle is able to traverse both the LIML 120 and the substrate 110 (e.g., cover glass) and exit the device. Rays at higher than the TIR critical angle will be reflected back into the luminescent layer 330a or 330b, where they may be scattered by the particles present in the luminescent layer 330a and change direction, exiting the device on a second (or third, or fourth, etc.) reflection. It is noted that this recycling effect is aided by the reflective walls 320 of the pixel (e.g., white or metal particle fdled photoresist or metal coated photoresist) and the bottom reflector. In the displays described herein, the bottom reflector may be provided by the bottom electrode of an OLED, which may be aluminum having an about 90 percent reflectivity.

[0075] As shown in FIGS. 4A-4D for QD-CC displays, the LIML layers 120 are advantageously positioned adjacent to and between the luminescent layers 330a and 330b and the corresponding color filter layers 140. Working together with the scattering media inside the luminescent layers 330a and / or the adhesive layer 324, reflective pixel walls 320, and the back reflector provided by the bottom contact of the light sources 340, the LIMLs 120 enable a significant enhancement of the display efficiency (e.g., by up to about 50 percent) by preventing light trapping at the glass-air boundary by TIR.Attorney Docket No.: SP24-249

[0076] FIG. 5 A is a simplified cross-sectional view of an exemplary display device 500a. In some embodiments, display device 500a is an OLED or electroluminescent quantum dot (EL- QD) display device. Display device 500a includes a substrate 110, a LIML 120, an adhesive layer 524, a plurality of walls 320 (e.g., pixel walls), a plurality of luminescent layers 530 (e.g., OLED or EL-QD), and a bottom electrode 536. Substrate 110, LIML 120, and each luminescent layer 530 may be similar to substrate 110, LIML 120, and luminescent layer 130, respectively, as previously described and illustrated with reference to FIG. 1A. The adhesive layer 524 includes a first surface 526 and a second surface 528 opposite to the first surface 526. The first surface 122 of the LIML 120 is proximate (e.g., on or contacting) the second surface 114 of the substrate 110. The second surface 124 of the LIML 120 includes a non-wetting surface. As previously described, the LIML 120 may, for example, include nanopillars, an at least partially decomposed sacrificial material, an aerogel, and / or a mixture of hollow silica nanoparticles and a polymer binder. The LIML 120 may include a plurality of gas filled voids (e.g., pores). The first surface 526 of the adhesive layer 524 contacts (e.g., directly contacts) the non-wetting surface 124 of the LIML 120 and seals the plurality of gas filled voids.

[0077] The plurality of walls 320 may contact (e.g., directly contact) the second surface 528 of the adhesive layer 524 and define a plurality of openings 360. Each opening 360 may have a circular, square, rectangular, hexagonal, or other suitable shape. In certain exemplary embodiments, the plurality of walls 320 may include a metal (e.g., Al) or metal veneer, a white or metal particle filled photoresist, or another suitable reflective material. The plurality of walls 320 reflect light rays, thereby further increasing the optical efficiency of the display device 500a. The plurality of walls 320 may be formed using photolithography processes and / or electroplating.

[0078] Each of the plurality of luminescent layers 530 is within a respective opening 360 and includes a first surface 532 and a second surface 534 opposite to the first surface 532. The first surface 532 of each luminescent layer 530 contacts (e.g., directly contacts) the second surface 528 of the adhesive layer 524 within a respective opening 360. Each of the plurality of luminescent layers 530 includes an OLED or EL-QD light source. The second surface 534 of each luminescent layer 530 directly contacts the bottom electrode 536. Bottom electrode 536 is a common electrode for each OLED or EL-QD light source. Bottom electrode 536, luminescent layers 530, and walls 320 may be fabricated on a substrate (not shown). LIML 120 may be fabricated on substrate 110. The substrate 110 and LIML 120 may then be joined to the luminescent layers 530 and walls 320 via adhesive layer 524.Attorney Docket No.: SP24-249

[0079] In some embodiments, the adhesive layer 524 may include an optically clear adhesive (e.g., silicone, acrylate, urethane, vinyl, ester, etc.) with scattering particles. In some embodiments, the adhesive layer 524 may include an optically clear adhesive without scattering particles and the top surface of the bottom electrode 536 may be roughened to provide a scattering function. In some embodiments, the adhesive layer 524 may include scattering particles and the top surface of the bottom electrode 536 may be roughened to provide an additional scattering function. The advantages of LIML 120 may be maximized by higher reflectivity from the walls 320 and from the bottom electrode 536.

[0080] FIG. 5B is a simplified cross-sectional view of another exemplary display device 500b. Display device 500b is similar to display device 500a previously described and illustrated with reference to FIG. 5A, except that display device 500b includes a blocking layer 150. The blocking layer 150 includes a first surface 152 and a second surface 154 opposite to the first surface 152. The blocking layer 150 is between (e.g., directly between) the LIML 120 and the adhesive layer 524, such that the second surface 124 of the LIML 120 contacts (e.g., directly contacts) the first surface 152 of the blocking layer 150, and the first surface 526 of the adhesive layer 524 contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150.

[0081] FIG. 5C is a simplified cross-sectional view of another exemplary display device 500c. Display device 500c is similar to display device 500a previously described and illustrated with reference to FIG. 5 A, except that display device 500c includes a plurality of color filter layers 140 in the respective plurality of openings 360. Each color filter layer 140 includes a first surface 142 and a second surface 144 opposite to the first surface 142. Each color filter layer 140 is between (e.g., directly between) the adhesive layer 524 and the respective luminescent layer 530, such that the second surface 528 of the adhesive layer 524 contacts (e.g., directly contacts) the first surface 142 of each color filter layer 140, and the second surface 144 of each color filter layer 140 contacts (e.g., directly contacts) the first surface 532 of the respective luminescent layer 530. Each color filter layer 140 may, for example, include a red color filter layer, a green color filter layer, and / or a blue color filter layer.

[0082] FIG. 5D is a simplified cross-sectional view of another exemplary display device 500d. Display device 500d is similar to display device 500c previously described and illustrated with reference to FIG. 5C, except that display device 500d includes a blocking layer 150. The blocking layer 150 includes a first surface 152 and a second surface 154 opposite to the first surface 152. The blocking layer 150 is between (e.g., directly between) the LIML 120Attorney Docket No.: SP24-249 and the adhesive layer 524, such that the second surface 124 of the LIML 120 contacts (e.g., directly contacts) the first surface 152 of the blocking layer 150, and the first surface 526 of the adhesive layer 524 contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150.

[0083] As illustrated in FIGS. 5A-5D, display devices 500a-500d include a continuous LIML 120, and in some embodiments a corresponding continuous blocking layer 150, that extends over the individual pixels. In these embodiments, the LIML 120 and the blocking layer 150 may be formed on the substrate 110, which may form the cover glass of the display devices.

[0084] FIG. 6A is a simplified cross-sectional view of an exemplary display device 600a. In some embodiments, display device 600a is an OLED or electroluminescent quantum dot (EL- QD) display device. Display device 600a includes a substrate 110, an adhesive layer 524, a plurality of walls 320 (e.g., pixel walls), a plurality of LIMLs 120, a plurality of luminescent layers 530 (e.g., OLED or EL-QD), and a bottom electrode 536. Substrate 110, each LIML 120, and each luminescent layer 530 may be similar to substrate 110, LIML 120, and luminescent layer 130, respectively, as previously described and illustrated with reference to FIG. 1 A. The adhesive layer 524 includes a first surface 526 and a second surface 528 opposite to the first surface 526. The first surface 526 of the adhesive layer 524 contacts (e.g., directly contacts) the second surface 114 of the substrate 110.

[0085] The plurality of walls 320 may contact (e.g., directly contact) the second surface 528 of the adhesive layer 524 and define a plurality of openings 360. Each opening 360 may have a circular, square, rectangular, hexagonal, or other suitable shape. In certain exemplary embodiments, the plurality of walls 320 may include a metal (e.g., Al) or metal veneer, a white or metal particle filled photoresist, or another suitable reflective material. The plurality of walls 320 reflect light rays, thereby further increasing the optical efficiency of the display device 600a. The plurality of walls 320 may be formed using photolithography processes and / or electroplating.

[0086] Each of the plurality of LIMLs 120 is within a respective opening 360 and includes a first surface 122 and a second surface 124 opposite to the first surface 122. Each of the plurality of luminescent layers 530 is within a respective opening 360 and includes a first surface 532 and a second surface 534 opposite to the first surface 532. The second surface 124 of each LIML 120 directly contacts the second surface 528 of the adhesive layer 524 within a respective opening 360. The first surface 532 of each luminescent layer 530 contacts (e.g., directly contacts) the first surface 122 of the respective LIML 120 within a respective opening 360. Each of the plurality of luminescent layers 530 includes an OLED or EL-QD light source.Attorney Docket No.: SP24-249The second surface 534 of each luminescent layer 530 directly contacts the bottom electrode 536. Bottom electrode 536 is a common electrode for each OLED or EL-QD light source. Bottom electrode 536, luminescent layers 530, LIMLs 120, and walls 320 may be fabricated on a substrate (not shown). The substrate 110 may then be joined to the LIMLs 120 and walls 320 via adhesive layer 524.

[0087] FIG. 6B is a simplified cross-sectional view of another exemplary display device 600b. Display device 600b is similar to display device 600a previously described and illustrated with reference to FIG. 6A, except that display device 600b includes a plurality of blocking layers 150. Each blocking layer 150 is within a respective opening 360 and includes a first surface 152 and a second surface 154 opposite to the first surface 152. Each blocking layer 150 is between (e.g., directly between) the respective LIML 120 and the adhesive layer 524, such that the second surface 124 of each LIML 120 contacts (e.g., directly contacts) the first surface 152 of the respective blocking layer 150, and the second surface 528 of the adhesive layer 524 contacts (e.g., directly contacts) the second surface 154 of each blocking layer 150.

[0088] FIG. 6C is a simplified cross-sectional view of another exemplary display device 600c. Display device 600c is similar to display device 600a previously described and illustrated with reference to FIG. 6A, except that display device 600c includes a plurality of scattering layers 624 in the respective plurality of openings 360. Each scattering layer 624 includes a first surface 626 and a second surface 628 opposite to the first surface 626. Each scattering layer 624 is between (e.g., directly between) the respective LIML 120 and the respective luminescent layer 530, such that the first surface 122 of the respective LIML 120 contacts (e.g., directly contacts) the first surface 626 of the respective scattering layer 624, and the second surface 628 of each scattering layer 624 contacts (e.g., directly contacts) the first surface 532 of the respective luminescent layer 530. Each scattering layer 624 may, for example, include an optically clear adhesive with scattering particles.

[0089] FIG. 6D is a simplified cross-sectional view of another exemplary display device 600d. Display device 600d is similar to display device 600c previously described and illustrated with reference to FIG. 6C, except that display device 600d includes a plurality of blocking layers 150. Each blocking layer 150 is within a respective opening 360 and includes a first surface 152 and a second surface 154 opposite to the first surface 152. Each blocking layer 150 is between (e.g., directly between) the respective LIML 120 and the adhesive layer 524, such that the second surface 124 of each LIML 120 contacts (e.g., directly contacts) the first surface 152 of the respective blocking layer 150, and the second surface 528 of theAttorney Docket No.: SP24-249 adhesive layer 524 contacts (e.g., directly contacts) the second surface 154 of each blocking layer 150.

[0090] FIG. 6E is a simplified cross-sectional view of another exemplary display device 600e. Display device 600e is similar to display device 600a previously described and illustrated with reference to FIG. 6A, except that display device 600e includes a plurality of color filter layers 140 in the respective plurality of openings 360. Each color filter layer 140 includes a first surface 142 and a second surface 144 opposite to the first surface 142. Each color filter layer 140 is between (e.g., directly between) the adhesive layer 524 and the respective LIML 120, such that the second surface 124 of the respective LIML 120 contacts (e.g., directly contacts) the first surface 142 of the respective color filter layer 140, and the second surface 144 of each color filter layer 140 contacts (e.g., directly contacts) the second surface 528 of the adhesive layer 524. Each color filter layer 140 may, for example, include a red color filter layer, a green color filter layer, and / or a blue color filter layer.

[0091] FIG. 6F is a simplified cross-sectional view of another exemplary display device 600f. Display device 600f is similar to display device 600e previously described and illustrated with reference to FIG. 6E, except that display device 600f includes a plurality of blocking layers 150. Each blocking layer 150 is within a respective opening 360 and includes a first surface 152 and a second surface 154 opposite to the first surface 152. Each blocking layer 150 is between (e.g., directly between) the respective LIML 120 and the respective color filter layer 140, such that the second surface 124 of the respective LIML 120 contacts (e.g., directly contacts) the first surface 152 of the respective blocking layer 150, and the first surface 142 of the respective color filter layer 140 contacts (e.g., directly contacts) the second surface 154 of the respective blocking layer 150.

[0092] FIG. 6G is a simplified cross-sectional view of another exemplary display device 600g. Display device 600g is similar to display device 600e previously described and illustrated with reference to FIG. 6E, except that display device 600g includes a plurality of scattering layers 624 in the respective plurality of openings 360. Each scattering layer 624 includes a first surface 626 and a second surface 628 opposite to the first surface 626. Each scattering layer 624 is between (e.g., directly between) the respective LIML 120 and the respective luminescent layer 530, such that the first surface 122 of the respective LIML 120 contacts (e.g., directly contacts) the first surface 626 of the respective scattering layer 624, and the second surface 628 of the respective scattering layer 624 contacts (e.g., directly contacts) the first surface 532 of the respective luminescent layer 530. Each scattering layer 624 may, for example, include an optically clear adhesive with scattering particles.Attorney Docket No.: SP24-249

[0093] FIG. 6H is a simplified cross-sectional view of another exemplary display device 600h. Display device 600h is similar to display device 600g previously described and illustrated with reference to FIG. 6G, except that display device 600h includes a plurality of blocking layers 150. Each blocking layer 150 is within a respective opening 360 and includes a first surface 152 and a second surface 154 opposite to the first surface 152. Each blocking layer 150 is between (e.g., directly between) the respective LIML 120 and the respective color filter layer 140, such that the second surface 124 of the respective LIML 120 contacts (e.g., directly contacts) the first surface 152 of the respective blocking layer 150, and the first surface 142 of the respective color filter layer 140 contacts (e.g., directly contacts) the second surface 154 of the respective blocking layer 150.

[0094] FIG. 7A is a simplified cross-sectional view of an exemplary display device 700a. In some embodiments, display device 700a is an OLED or electroluminescent quantum dot (EL- QD) display device. Display device 700a includes a substrate 110, a plurality of walls 320 (e.g., pixel walls), a plurality of color filter layers 140, a plurality of LIMLs 120, an adhesive layer 524, an encapsulation layer 322, and an emitter array 739. Emitter array 739 includes a plurality of walls 720, a plurality of luminescent layers 530 (e.g., OLED or EL-QD), and a bottom electrode 536. Substrate 110, each color filter layer 140, each LIML 120, and each luminescent layer 530 may be similar to substrate 110, color filter layer 140, LIML 120, and luminescent layer 130, respectively, as previously described and illustrated with reference to FIG. 1C.

[0095] The plurality of walls 320 may contact (e.g., directly contact) the second surface 114 of the substrate 110 and define a plurality of openings 360. Each opening 360 may have a circular, square, rectangular, hexagonal, or other suitable shape. In certain exemplary embodiments, the plurality of walls 320 may include a metal (e.g., Al) or metal veneer, a white or metal particle filled photoresist, or another suitable reflective material. The plurality of walls 320 reflect light rays, thereby further increasing the optical efficiency of the display device 700a. The plurality of walls 320 may be formed using photolithography processes and / or electroplating.

[0096] Each of the plurality of color filter layers 140 is within a respective opening 360 and includes a first surface 142 and a second surface 144 opposite to the first surface 142. Each of the plurality of LIMLs 120 is within a respective opening 360 and includes a first surface 122 and a second surface 124 opposite to the first surface 122. The first surface 142 of each color filter layer 140 contacts (e.g., directly contacts) the second surface 114 of the substrate 110. Each of the plurality of color filter layers 140 includes color pigments or dyes within a polymer.Attorney Docket No.: SP24-249The color filter layers 140 may be formed by printing a photoresist or ink layer including color pigments or dyes within a curable polymer directly on the second surface 114 of the substrate 110 within each respective opening 360. Following printing, the photoresist or ink may be cured, such as by an ultraviolet light, to form the color filter layers 140. After curing, each color filter layer 140 includes a fixed geometry.

[0097] The second surface 144 of each color filter layer 140 contacts (e.g., directly contacts) the first surface 122 of the respective LIML 120. The adhesive layer 524 includes a first surface 526 and a second surface 528 opposite to the first surface 526. The second surface 124 of each LIML 120 (and the bottom surface of each wall 320) contacts (e.g., directly contacts) the first surface 526 of the adhesive layer 524. The second surface 124 of each LIML 120 includes a non-wetting surface. As previously described, each LIML 120 may, for example, include nanopillars, an at least partially decomposed sacrificial material, an aerogel, and / or a mixture of hollow silica nanoparticles and a polymer binder. Each LIML 120 may include a plurality of gas filled voids (e.g., pores) sealed by the adhesive layer 524. The second surface 528 of the adhesive layer 524 contacts (e.g., directly contacts) the top surface of the encapsulation layer 322.

[0098] In certain exemplary embodiments, the plurality of walls 720 may correspond to walls 320 and may include a metal (e.g., Al) or metal veneer, a white or metal particle filled photoresist, or another suitable reflective material. The plurality of walls 720 reflect light rays, thereby further increasing the optical efficiency of the display device 700a. The plurality of walls 720 may be formed using photolithography processes and / or electroplating.

[0099] Each of the plurality of luminescent layers 530 is between respective walls 720 (e.g., corresponding to walls 320) and includes a first surface 532 and a second surface 534 opposite to the first surface 532. The first surface 532 of each luminescent layer 530 contacts (e.g., directly contacts) the bottom surface of the encapsulation layer 322. Each of the plurality of luminescent layers 530 includes an OLED or EL-QD light source. The second surface 534 of each luminescent layer 530 directly contacts the bottom electrode 536. Bottom electrode 536 is a common electrode for each OLED or EL-QD light source. Bottom electrode 536, luminescent layers 530, walls 720, and encapsulation layer 322 may be fabricated on a substrate (not shown). Walls 320, color filter layers 140, and LIMLs 120 may be fabricated on substrate 110. The substrate 110, walls 320, color filter layers 140, and LIMLs 120 may then be joined to the encapsulation layer 322 via adhesive layer 524.

[0100] Encapsulation layer 322 encapsulates the plurality of walls 720 and the plurality of luminescent layers 530. Encapsulation layer 322 is between (e.g., directly between) theAttorney Docket No.: SP24-249 adhesive layer 524 and the emitter array 739. In certain exemplary embodiments, the encapsulation layer 322 is a thin film encapsulation layer.

[0101] In some embodiments, the adhesive layer 524 may include an optically clear adhesive (e.g., silicone, acrylate, urethane, vinyl, ester, etc.) with scattering particles. In some embodiments, the adhesive layer 524 may include an optically clear adhesive without scattering particles and the top surface of the bottom electrode 536 may be roughened to provide a scattering function. In some embodiments, the adhesive layer 524 may include scattering particles and the top surface of the bottom electrode 536 may be roughened to provide an additional scattering function. The advantages of LIMLs 120 may be maximized by higher reflectivity from the walls 320 and 720 and from the bottom electrode 536.

[0102] FIG. 7B is a simplified cross-sectional view of another exemplary display device 700b. Display device 700b is similar to display device 700a previously described and illustrated with reference to FIG. 7A, except that display device 700b includes a blocking layer 150. Blocking layer 150 includes a first surface 152 and a second surface 154 opposite to the first surface 152. Blocking layer 150 is between (e.g., directly between) the walls 320 and the LIMLs 120 and the adhesive layer 524, such that the second surface 124 of each LIML 120 contacts (e.g., directly contacts) the first surface 152 of the blocking layer 150, the bottom surface of each wall 320 contacts (e.g., directly contacts) the first surface 152 of the blocking layer 150, and the first surface 526 of the adhesive layer 524 contacts (e.g., directly contacts) the second surface 154 of the blocking layer 150.

[0103] FIG. 7C is a simplified cross-sectional view of another exemplary display device 700c. Display device 700c is similar to display device 700a previously described and illustrated with reference to FIG. 7A, except that display device 700c includes a plurality of scattering layers 624 in the respective plurality of openings 360. Each scattering layer 624 includes a first surface 626 and a second surface 628 opposite to the first surface 626. Each scattering layer 624 is between (e.g., directly between) the respective LIML 120 and the adhesive layer 524, such that the second surface 124 of the respective LIML 120 contacts (e.g., directly contacts) the first surface 626 of the respective scattering layer 624, and the second surface 628 of the respective scattering layer 624 contacts (e.g., directly contacts) the first surface 526 of the adhesive layer 524. Each scattering layer 624 may, for example, include an optically clear adhesive with scattering particles. In this embodiment, adhesive layer 524 may include an optically clear adhesive without scattering particles.

[0104] FIG. 7D is a simplified cross-sectional view of another exemplary display device 700d. Display device 700d is similar to display device 700c previously described andAttorney Docket No.: SP24-249 illustrated with reference to FIG. 7C, except that display device 700c includes a plurality of blocking layers 150. Each blocking layer 150 is within a respective opening 360 and includes a first surface 152 and a second surface 154 opposite to the first surface 152. Each blocking layer 150 is between (e.g., directly between) the respective LIML 120 and the respective scattering layer 624, such that the second surface 124 of the respective LIML 120 contacts (e.g., directly contacts) the first surface 152 of the respective blocking layer 150, and the first surface 626 of the respective scattering layer 624 contacts (e.g., directly contacts) the second surface 154 of the respective blocking layer 150.

[0105] It is noted that the display devices of FIGS. 3A-7D to improve the emissive display device efficiency and the methods of making the display devices described herein are applicable not only to the displays described herein, but also to other display types not described, such as micro-LED displays. The principle of operation, by local recycling of the emitted light, and materials and processes for making the LIMLs 120 are the same as described herein. It is noted that in all cases, the LIML 120 returns the high angle light rays back into the luminescent layer. For this light to be efficiently recycled and have a chance to exit the device on a subsequent arrival to the LIML 120, all sources of optical loss should be minimized, and a scattering agent or component should be added. Therefore, white or reflective pixel walls as described herein are beneficial for all display types. A dichroic reflector may be added for QD color converted micro-LED displays. As described herein, in OLED and EL-QD displays, the back reflector may be provided by the metallic bottom contact, which may be roughened, or an additional scattering layer may be added between the luminescent layer and the LIML 120 to enable scattering.

[0106] FIGS. 8A-8G are flow diagrams of an exemplary method 800 for fabricating a display device, such as device lOOa-lOOf, 200a-200d, 300a-300h, 400a-400d, 500a-500d, 600a-600h, or 700a-700d previously described and illustrated with reference to FIGS. 1A-1F, 2A-2D, SASH, 4A-4D, 5A-5D, 6A-6H, and 7A-7D respectively. As illustrated in FIG. 8A at 802, method 800 may include forming a low-index material layer (LIML) (e.g., 120, 120a, 120b) comprising a plurality of gas filled voids (e.g., 212, 220, 222) on a substrate (e.g., 110). At 804, method 800 may include applying a photoresist or ink layer on the LIML. The photoresist or ink layer may include luminescent emitter particles (e.g., quantum dots, phosphors, fluorophores, nanocrystals), scattering particles, and / or color pigments or dyes. At 806, method 800 may include curing (e.g., by exposing the photoresist or ink to ultraviolet light) the photoresist or ink layer to form a luminescent layer (e.g., 130, 330a, 330b) or a color filter layer (e.g., 140). In some embodiments, forming the LIML comprises forming the LIML comprising a nonAtorney Docket No.: SP24-249 weting surface (e.g., 124). In this embodiment, applying the photoresist or ink layer may comprise applying the photoresist or ink layer directly on the non-weting surface to seal the plurality of gas fdled voids.

[0107] As illustrated in FIG. 8B at 808, method 800 may further include applying a blocking layer (e.g., 150) directly on the LIML to seal the plurality of gas fdled voids. In this embodiment, applying the photoresist or ink layer may comprise applying the photoresist or ink layer directly on the blocking layer.

[0108] As illustrated in FIG. 8C, step 802 of method 800 of FIG. 8A may further include method 802a. At 810, method 802a may include disposing a mask comprising nanostructured metal-containing features on a surface of the substrate. At 812, method 802a may include dry etching portions of the surface of the substrate on which the mask is not disposed. At 814, method 802a may include removing the nanostructured metal-containing features and / or oxidizing the nanostructured metal -containing features of the mask. Method 802a may be used to form a LIML 120a including a plurality of nanopillars 210 separated by a plurality of voids 212 as previously described and illustrated with reference to FIG. 2A.

[0109] As illustrated in FIG. 8D, step 802 of method 800 of FIG. 8A may further include method 802b. At 816, method 802b may include forming a layer of aerogel on the substrate. As illustrated in FIG. 8E at 818, method 802b may further include applying a silane treatment to the aerogel. In certain exemplary embodiments, the aerogel by itself forms a non-weting surface and the silane coating is excluded. In other embodiments, the silane treatment applied to the aerogel forms the non-weting surface. Method 802b may be used to form a LIML 120b including a plurality of internal pores 220 and a plurality of surface pores 222 as previously described and illustrated with reference to FIG. 2C.

[0110] As illustrated in FIG. 8F, step 802 of method 800 of FIG. 8A may further include method 802c. At 820, method 802c may include applying a sacrificial layer on the substrate. At 822, method 802c may include at least partially decomposing the sacrificial layer. In some embodiments, at least partially decomposing the sacrificial layer may include boiling, sublimating, decomposing, or releasing a dissolved gas at a relatively low temperature (e.g., less than about 100 degrees Celsius) or under a laser illumination between the substrate and the color filter layer or between the color filter layer and the luminescent layer. Once the structure is completed, the structure may be kept at a high enough temperature or exposed to the laser light until the vapor, released gas, or the decomposition products form an air gap or a highly porous layer. Method 802c may be used to form a LIML 120b including a plurality of internalAttorney Docket No.: SP24-249 pores 220 and a plurality of surface pores 222 as previously described and illustrated with reference to FIG. 2C.

[0111] As illustrated in FIG. 8G, step 802 of method 800 of FIG. 8A may further include method 802d. At 824, method 802d may include applying a mixture of hollow silica nanoparticles and a polymer binder on a surface of the substrate. Method 802d may be used to form a LIML 120b including a plurality of internal pores 220 and a plurality of surface pores 222 as previously described and illustrated with reference to FIG. 2C. In other embodiments, other suitable methods may be used to form the LIML including a non-wetting surface.

[0112] It will be apparent to those skilled in the art that various modifications and variations can be made to embodiments of the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present disclosure cover such modifications and variations provided they come within the scope of the appended claims and their equivalents.

Claims

Attorney Docket No.: SP24-249What is claimed is:1 . A device comprising: a substrate; a low-index material layer (LIML) proximate the substrate, the LIML comprising a plurality of gas fdled voids; and a luminescent layer proximate the LIML, the luminescent layer comprising luminescent emitter particles.

2. The device of claim 1, wherein the LIML comprises a non- wetting surface, and wherein the luminescent layer directly contacts the non-wetting surface and seals the plurality of gas fdled voids.

3. The device of claim 1, further comprising: a color fdter layer between the LIML and the luminescent layer, wherein the LIML comprises a non-wetting surface, and wherein the color fdter layer directly contacts the non-wetting surface and seals the plurality of gas fdled voids.

4. The device of claim 1, further comprising: an adhesive layer between the LIML and the luminescent layer, wherein the LIML comprises a non-wetting surface, and wherein the adhesive layer directly contacts the non-wetting surface and seals the plurality of gas fdled voids.

5. The device of claim 1, further comprising: a scattering layer between the LIML and the luminescent layer.

6. The device of claim 1, further comprising: a blocking layer directly contacting the LIML and sealing the plurality of gas fdled voids.Attorney Docket No.: SP24-2497. The device of claim 1, wherein the luminescent emitter particles comprise at least one of quantum dots, phosphors, fluorophores, nanocrystals, or organic light emitters.

8. The device of claim 1, wherein the LIML comprises a refractive index less than about 1.5.

9. The device of claim 1, further comprising: a color filter layer between the substrate and the LIML.

10. The device of claim 1, wherein the LIML comprises at least one of nanopillars, an at least partially decomposed sacrificial material, an aerogel, or a mixture of hollow silica nanoparticles and a polymer binder.

11. The device of claim 1, wherein the luminescent layer comprises scattering particles.

12. A display device comprising: a substrate; a plurality of walls proximate the substrate and defining a plurality of openings; a plurality of low-index material layers (LIMLs) proximate the substrate, each LIML within a respective opening of the plurality of openings and comprising a plurality of gas filled voids; and a plurality of luminescent layers, each luminescent layer within a respective opening of the plurality of openings proximate a respective LIML of the plurality of LIMLs and comprising luminescent emitter particles.

13. The display device of claim 12, further comprising: a plurality of blocking layers, each blocking layer within a respective opening of the plurality of openings and directly contacting a respective LIML and sealing the respective plurality of gas filled voids.

14. The display device of claim 12, wherein the plurality of walls are reflective.Attorney Docket No.: SP24-24915. The display device of claim 12, wherein each LIML of the plurality of LIMLs comprises at least one of nanopillars, an at least partially decomposed sacrificial material, an aerogel, or a mixture of hollow silica nanoparticles and a polymer binder.

16. A method for fabricating a display device, the method comprising: forming a low-index material layer (LIML) comprising a plurality of gas filled voids on a substrate; applying a photoresist or ink layer on the LIML; and curing the photoresist or ink layer to form a luminescent layer or a color filter layer.

17. The method of claim 16, wherein forming the LIML comprises forming the LIML comprising a non-wetting surface, and wherein applying the photoresist or ink layer comprises applying the photoresist or ink layer directly on the non-wetting surface to seal the plurality of gas filled voids.

18. The method of claim 16, further comprising: applying a blocking layer directly on the LIML to seal the plurality of gas filled voids.

19. The method of claim 16, wherein forming the LIML comprises: disposing a mask comprising nanostructured metal-containing features on a surface of the substrate; dry etching portions of the surface of the substrate on which the mask is not disposed; and removing the nanostructured metal-containing features and / or oxidizing the nanostructured metal-containing features of the mask.

20. The method of claim 16, wherein forming the LIML comprises: forming a layer of aerogel on the substrate.

21. The method of claim 20, wherein forming the LIML comprises: applying a silane treatment to the aerogel.

22. The method of claim 16, wherein forming the LIML comprises: applying a sacrificial layer on the substrate; andAttorney Docket No.: SP24-249 at least partially decomposing the sacrificial layer.

23. The method of claim 16, wherein forming the LIML comprises: applying a mixture of hollow silica nanoparticles and a polymer binder on the substrate.

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